Functions of the adaptor protein p66^Shc in solid tumors

Abstract

p66^Shc is a 66 kDa Src homology 2 domain containing (Shc) adaptor protein homolog. Previous studies have demonstrated that p66^Shc is a proapoptotic protein involved in the cellular response to oxidative stress and in regulating mammalian lifespan. However, accumulating evidence also indicates its critical role in solid tumor progression. The expression of p66^Shc varies in different types of solid tumors, and it can paradoxically promote as well as suppress tumor progression, survival, and metastasis, depending on the cellular context. In this review, we discuss its functions in various solid tumors, the mechanisms by which it mediates the process of anoikis (detachment-induced cell death), and the epigenetic mechanisms that regulate its expression. These studies indicate the potential of p66^Shc as a novel prognostic marker and therapeutic target for the prevention of tumor progression and metastasis.

Keywords

adaptor protein / p66^Shc / anoikis / metastasis / autophagy

Introduction

p66^Shc is an isoform of ShcA, which belongs to the Shc adaptor protein family. ShcA is expressed as three isoforms, p46^Shc, p52^Shc, and p66^Shc, with molecular masses of 46, 52, and 66 kDa, respectively. In humans, all ShcA isoforms are encoded by the same gene, but their expression is regulated by different promoters ( Pelicci et al., 1992; Luzi et al., 2000; Shen and Tsao, 2004). p66^Shc, p52^Shc, and p46^Shc share three functionally identical domains: an N-terminal phosphotyrosine binding domain (PTB), a collagen homology domain (CH1), and a C-terminal Src homology 2 domain (SH2)( Migliaccio et al., 1997; Luzi et al., 2000). p66^Shc is the longest ShcA isoform with an unique collagen homology domain (CH2) at the N terminus (Fig. 1). The CH2 domain is comprised of 110 amino acids, which is rich in glycine and proline residues. Two critical serine phosphorylation (S36 and S54) sites also reside in the CH2 domain ( Migliaccio et al., 1997). S36 is a critical regulatory site for the apoptotic activity and oxidative stress response of p66^Shc ( Foschi et al., 2001; Faisal et al., 2002; Pellegrini et al., 2005; Veeramani et al., 2005a; Galimov et al., 2014), and S54 is important for its stability ( Khanday et al., 2006). A cytochrome c binding (CB) region is present between the CH2 and PTB domain in p66^Shc protein, which is primarily involved in the regulation of oxidative stress in the mitochondria ( Giorgio et al., 2005).

p66^Shc has been extensively studied, primarily for its role in the cellular response to oxidative stress and in regulating mammalian lifespan. In mesenchymal progenitor and osteoblastic cell models, H₂O₂ activates a protein kinase C (PKC)-β/p66^Shc/NF-kB signaling cascade, wherein p66^Shc functions as an essential mediator of apoptosis induced by H₂O₂ in the osteoblastic cells ( Almeida et al., 2010). Deletion of p66^Shc in mice (p66^Shc-/- ) decreases the incidence of aging-associated diseases (e.g., atherosclerosis) and prolongs lifespan ( Migliaccio et al., 1999; Napoli et al., 2003; Francia et al., 2004). p66^Shc is primarily expressed in epithelial cells; whereas, it is poorly expressed in peripheral blood lymphocytes, hematopoietic cell lines, and neurons. Its expression varies in different cancer cell lines ( Pelicci et al., 1992; Xie and Hung, 1996; Migliaccio et al., 1997; Stevenson and Frackelton, 1998; Jackson et al., 2000; Veeramani et al., 2005a). Notably, the diverse expression of p66^Shc might be correlated with its differential functions in cells. Importantly, a growing number of studies have reported its involvement in cancer development, progression and metastasis ( Alam et al., 2009). Herein, we review the different functions of p66^Shc in solid tumors, which may provide potential insight into cancer therapies targeting p66^Shc.

Functions of p66^Shc in solid tumors

p66^Shc has been shown to promote cancer as well as suppress cancer. The expression of p66^Shc varies in different types of cancer. The expression of p66^Shc is elevated in many cancers, including prostate cancer (PCa) ( Lee et al., 2004), esophageal cancer ( Chen and Yang, 2001), thyroid cancer ( Pelicci et al., 1995), ovarian cancer (OCa) ( Muniyan et al., 2015), and colon cancer ( Grossman et al., 2007). In contrast, the expression of p66^Shc is reduced in human lung cancers ( Du et al., 2013; Zheng et al., 2013) and in malignant ovarian surface epithelial cells ( Abdollahi et al., 2003). Differences in the expression of p66^Shc in various cancers may reflect differences in its biological functions in solid tumors.

p66^Shc promotes tumor progression

One of the strongest evidence that Shc is directly involved in cancer cell metastasis is provided by a study on transgenic mice strains expressing polyoma virus middle T antigen with a mutated Shc binding site ( Webster et al., 1998). Female transgenic mice developed focal mammary tumors, but surprisingly, in a number of metastatic tumors, the mutated Shc binding site had reverted to the wild-type sequence. This result suggests that the process of metastasis provides a strong selection pressure for a functional Shc binding site in vivo. This study also implicated p66^Shc in specific steps of metastasis. The expression and activation of p66^Shc was elevated in a highly metastatic variant (F-11) of the human breast cancer cell line, MDA-MB-231, compared to the parental cell line ( Jackson et al., 2000). Moreover, in breast cancer tissues associated with lymph node metastasis, p66^Shc expression was elevated, which correlated with a greater number of positive nodes ( Jackson et al., 2000). These results suggest that cell motility and invasion are influenced by p66^Shc rather than by the MAPK pathway ( Jackson et al., 2000). Conversely, reduced ShcA levels or the expression of a dominant-negative ShcA mutant limited TGF-β-induced motility and the invasion of Neu/ErbB2-expressing breast cancer cells ( Northey et al., 2008). Together, these results suggest a critical role of p66^Shc in the migration and invasion of cancer cells.

p66^Shc may also play a critical role in steroid-stimulated cancer cell proliferation. Steroid hormone-related cancers include cancers of the prostate, testes, breast, ovary, uterine endometrium, and thyroid ( Henderson and Feigelson, 2000). In PCa, overexpression of p66^Shc increases basal cell proliferation. Conversely, p66^Shc knockdown with small interfering RNAs reduced dihydrotestosterone (DHT)-induced cell proliferation. A novel role for the p66^Shc-ROS (reactive oxygen species) pathway in androgen-induced cell proliferation has also been reported ( Veeramani et al., 2008). Androgens induce the production of ROS in PCa cells through the increased expression of p66^Shc, resulting in the inactivation of tyrosine phosphatase activity required for the activation of an interacting tyrosine kinase and increased cell proliferation and tumorigenicity ( Veeramani et al., 2012). Similarly, the regulation of OCa cell proliferation by p66^Shc has also been investigated. Among the cells lines tested, the slowest growing, OVCAR-3, expressed the lowest endogenous levels of p66^Shc, and overexpression of p66^Shc resulted in increased growth and proliferation ( Muniyan et al., 2015). Treatment of OCa cells with steroids resulted in an upregulation of p66^Shc levels and increased cell proliferation; conversely, treatment with steroid receptor antagonists resulted in a downregulation of p66^Shc levels ( Alam et al., 2009). In CaOV-3 cells treated with estrogen (E2), p66^Shc protein levels were elevated, which correlated with increased ROS production, ErbB2 and extracellular signal-regulated kinase (ERK)/MAPK activation, and cell proliferation ( Muniyan et al., 2015). p66^Shc forms a trimeric complex with alpha-1-syntrophin and Grb2, which can trigger cell proliferation and migration in MCF-7 and HBL-100 breast cancer cell lines; knockdown of p66^Shc using siRNAs decreased cell proliferation. Together, these results ( Bhat et al., 2014) clearly establish a causal relationship between p66^Shc protein and cell proliferation.

p66^Shc acts as a tumor suppressor

Despite considerable evidence demonstrating that p66^Shc promotes tumor progression, p66^Shc can also function as an important tumor suppressor by inhibiting cancer cell survival and metastasis. Recent studies have shown that p66^Shc regulates cancer cell apoptosis or anoikis (detachment-induced cell death). For example, phenethyl isothiocyanate (PEITC) treatment of PC-3 and LNCaP PCa cells resulted in the induction of p66^Shc expression, phosphorylation of S36, and selective inhibition of the growth of PCa cells by inducing apoptosis. Furthermore, PEITC treatment increased the binding of p66^Shc with peptidyl-prolyl isomerase (Pin1), and induced the translocation of p66^Shc to the mitochondria ( Xiao and Singh, 2010). In addition, p66^Shc is a stronger mediator of pro-death signaling in PC-3 cancer cells than in the PNT1A cells (noncancerous human prostate epithelial cells) after diallyl trisulfide (DATS) treatment ( Borkowska et al., 2013). Moreover, p66^Shc deficiency increases apoptosis resistance by nutrient deprivation in human lung adenocarcinoma A549 cells ( Zheng et al., 2013). p66^Shc also functions as a focal adhesion protein, and mediates anoikis in epithelial cells through RhoA-dependent anchorage sensing ( Ma et al., 2010). p66^Shc is downregulated in mouse Lewis lung carcinoma (LLC) and two cell lines of human small cell lung cancer (SCLC; H69 and H209). These cells exhibit aggressive metastatic behavior, presumably by bypassing anoikis through the constitutive activation of Ras. Interestingly, re-expression of p66^Shc in these cells restores anoikis ( Ma et al., 2010). These results suggest that p66^Shc may act as an important tumor suppressor. In clinical human lung cancer samples and cancer cell lines, the promoter of p66^Shc is hypermethylated at specific CpG sites in the early post-transcriptional region of p66^Shc. Hypermethylation silences its expression and may contribute to the invasion and metastasis cascade ( Du et al., 2013). Thus, the epigenetic repression of p66^Shc in cancer cells might be the key to the upregulation of Nrf2, and enhanced cell survival and tumor progression. The epithelial-to-mesenchymal transition (EMT) program is crucial for epithelial cancer cell progression. We have found that p66^Shc, which regulates ZEB1 within a negative feedback loop, suppresses fibrotic EMT responses ( Li et al., 2015). ZEB1, a well characterized EMT transcription factor and an activator of EMT, promotes tumorigenicity and metastasis. The expression of p66^Shc represses ZEB1. The p66^Shc promoter is also inhibited by ZEB1, which can induce fibrotic EMT responses and increase cell invasion and migration in lung cancer cells. Aiolos, a hematopoietic transcription factor, can promote cancer cell survival in an unanchored state by altering the chromatin structure surrounding the SHC1 gene, leading to an isoform-specific silencing of p66^Shc ( Li et al., 2014). Our studies reveal in depth mechanisms by which p66^Shc prevents metastatic behavior.

Functional mechanism of p66^Shc

p66^Shc regulates anchorage dependence and mediates anoikis

Integrin-dependent attachment of parenchymal cells to solid structures is required for their survival. As a consequence of anchorage dependence, most tissue cells initiate apoptotic death within hours of being suspended in a fluid environment, a process termed anoikis ( Frisch and Francis, 1994). Physiological anoikis maintains homeostasis in developing and adult tissues ( Mailleux et al., 2007); whereas, pathological anoikis resistance is implicated in malignant cell metastasis ( Ma et al., 2010).

Presently, anoikis is thought to be regulated by the withdrawal of integrin-related outside-in survival signals. This is supported by the observation that the enforced activation of various signaling components downstream of integrin signaling pathways are sufficient to confer anoikis resistance ( Frisch and Francis, 1994; Frisch et al., 1996; Gilmore, 2005; Martin et al., 2006). The binding of extracellular matrix components alone is not sufficient to prevent anoikis, since in the absence of structural matrix rigidity, RGD (Arg-Gly-Asp)-mediated integrin binding does not prevent anoikis ( Re et al., 1994; Chen et al., 1997). Thus, until recently, the molecular basis for attachment sensing during anoikis has been poorly understood. However, we recently discovered that p66^Shc permits activation of RhoA, resulting in tension-dependent death of suspended cells ( Ma et al., 2007). Anoikis sensitivity correlates with the upregulation of p66^Shc, induced by either external or endogenous mechanisms, in endothelial, epithelial, and mesenchymal cells. Lack of p66^Shc bypasses anoikis, whereas re-expression of p66^Shc restores anoikis. p66^Shc localizes to focal adhesions in attached cells and results in the focal activation of RhoA GTPase at regions of integrin anchorage. Because RhoA increases tension at integrin attachment sites ( Nobes and Hall, 1995), in detached cells, the tension would be applied among unanchored sites, allowing a mechanical readout for detachment. Upon ECM detachment, this p66^Shc-dependent tension test detects a load failure, leading to RhoA-dependent anoikis ( Ma et al., 2007). Nevertheless, the mechanism by which unopposed tension causes cell death is unclear. In metastatic cancer cells, p66^Shc mediates attachment sensing and anoikis. Knockdown of p66^Shc in lung tumor cells leads to unrestrained Ras activation, resulting in the downstream suppression of RhoA and prevention of anoikis ( Ma et al., 2010). The small-cell lung cancer and LLC cell lines, which lack p66^Shc, exhibit constitutive K-Ras activation, which can be suppressed by the ectopic expression of p66^Shc. Our data further suggest that p66^Shc restrains the hyperactivation of Rac1 and deactivation of RhoA downstream of Ras. Downstream Ras-dependent survival signals (e.g., Akt and ERK) may also contribute to anoikis resistance ( Ma et al., 2010).

Aiolos suppresses p66^Shc

Aiolos is frequently expressed in lung cancers and is correlated with markedly reduced patient survival. In lung cancer tissues and isolated single cells, the expression of p66^Shc is inversely correlated with that of Aiolos, which confers anoikis resistance and promotes lung cancer metastasis ( Li et al., 2014). Aiolos, a member of the Ikaros zinc finger family, is a lymphocyte lineage-restricted transcription factor. Its expression is generally restricted to lymphoid cells ( Morgan et al., 1997). Aiolos is involved in hematopoietic cell development. Aiolos is detected at low levels in pro-B and double negative (CD4⁻ CD8⁻) thymocyte precursors but is upregulated in cells as they progress to pre-B and double positive (CD4⁺ CD8⁺) stages of differentiation. Aiolos expression peaks in mature peripheral B cells ( Wang et al., 1998; Thompson et al., 2007). Notably, bioinformatic analysis of the transcriptome of some human breast cancers shows that Aiolos expression is upregulated ( Kilpinen et al., 2008). However, the function of Aiolos in carcinomas has not been well characterized. Our microarray analysis shows that multiple genes correlated with cellular adhesion are downregulated in A549 cells re-expressing Aiolos ( Li et al., 2014). Transient expression of Aiolos also selectively decreased p66^Shc protein levels in A549, HepG2, and MDA-MB-231 cells, confirming Aiolos inhibits p66^Shc expression. Furthermore, p66^Shc transcription requires a long-range physical interaction between the primary enhancer, E2, and the p66^Shc promoter in lung cancer cells. Aiolos associates with E2 and nearby surrounding regions, resulting in the alteration of higher order chromatin structures, disruption of enhancer-promoter interactions, and silencing of p66^Shc transcription. Thus, Aiolos contributes to anoikis resistance in vitro and in vivo.

p66^Shc modulates ROS production ( Nemoto and Finkel, 2002; Giorgio et al., 2005; Khanday et al., 2006), which is mainly produced by mitochondrial respiration ( Veeramani et al., 2012; Galimov et al., 2014). ROS induces oxidative damage, which may result in tissue dysfunction ( Trinei et al., 2013). In the mitochondrial intermembrane space, p66^Shc binds to cytochrome c, acting as an oxidoreductase and generating ROS ( Nemoto and Finkel, 2002; Giorgio et al., 2005). In addition, p66^Shc also mediates the production of ROS from the nucleus and plasma membrane ( Nemoto and Finkel, 2002; Khanday et al., 2006). In turn, elevated ROS level induces the phosphorylation of p66^Shc protein at S36, further promoting ROS generation ( Nemoto and Finkel, 2002; Orsini et al., 2004). ROS generated by p66^Shc has multiple functions in carcinogenesis. First, ROS may contribute to tumor cell proliferation. Stimulation of PCa cells with androgens induced the production of ROS through the elevation of p66^Shc protein levels, resulting in increased cell proliferation and enhanced tumorigenicity ( Veeramani et al., 2012). ROS produced by p66^Shc inactivates cellular prostatic acid phosphatase (cPAcP), which is a biomarker of PCa ( Sakai et al., 1992; Varma et al., 2004) and which inhibits PCa growth as a protein tyrosine phosphatase (PTPase) ( Lin and Meng, 1996; Lin et al., 2001; Veeramani et al., 2005a; Veeramani et al., 2005b). Inhibition of cPAcP then activates ErbB2 and ERK/MAPK, which promote cell growth, survival and tumorigenicity ( Veeramani et al., 2005a). Increased p66^Shc levels and ROS production contribute to cell growth in 5α-dihydrotestosterone (DHT)-treated PCa cells as well ( Veeramani et al., 2008). Second, the pro-apoptotic effects of ROS are well known. ROS accumulation is secondary to the progress of the apoptotic process. Accumulated ROS can activate the apoptotic pathway, which includes the collapse of the mitochondrial transmembrane potential ( Malhotra et al., 2009) and release of proapoptotic factors, such as cytochrome c ( Giorgio et al., 2005). PEITC selectively inhibits the growth of human PCa cells by inducing ROS production and apoptosis, for which p66^Shc is indispensable ( Xiao and Singh, 2010). PEITC treatment enhances PKC_β-mediated S36 phosphorylation of p66^Shc, which increases its association with Pin1 and promotes its translocation to the mitochondria. p66^Shc protein, localized to the mitochondria, is released from HSP70 and stimulates ROS production, leading to caspase-3 activation and apoptotic cell death ( Xiao and Singh, 2010). Therefore, the production of ROS by p66^Shc plays a controversial but critical role in cancer cell survival and death.

p66^Shc induces autophagy

Autophagy is an evolutionarily conserved lysosome-dependent process, wherein cytosolic components are enzymatically degraded and recycled in response to a wide variety of stressful conditions including ionic dysfunction, protein aggregation, proteasome failure, and energetic oxygen and nutrient deprivation ( Levine, 2007; Deffieu et al., 2009). The role of autophagy in cancer is complex and controversial. Autophagy contributes to the survival and growth of cancer cells under stressful conditions. For instance, serum starvation induces autophagy and inhibits apoptosis in SHSY5Y cells through the upregulation of NF-κB and Bcl-2 and downregulation of Bax and caspase-3 ( Mohan et al., 2011). Under environmental metabolic stress, lysosomal associated transmembrane protein, LAPTM4B, is elevated, which increases autophagic flux and promotes breast tumor growth in vivo ( Li et al., 2011). However, autophagy can also limit the survival and growth of cancer cells. In several tumor types, autophagy deficiency may positively correlate with the tumorigenesis when Atgs are mutated ( Wirawan et al., 2012). The cytoprotective enzyme, Heme oxygenase-1 (HO-1), can reduce autophagy and promote the survival of tumor cells against chemotherapy ( Banerjee et al., 2012).

p66^Shc may be involved in the process of autophagy induced by nutrient deprivation ( Zheng et al., 2013). Non-small lung cancer A549 cells express high basal levels of phosphorylated ERK1/2 (Thr202/Tyr204) and phosphorylated Akt1(Ser473), which decrease with nutrient deprivation. ERK1/2 are conserved serine/threonine kinases that regulate many cellular programs, including autophagy ( Pattingre et al., 2003). High constitutive ERK activity is implicated in suppressing autophagy in some cancers. Aberrant sustained activation of ERK by the carcinogen, Lindane, disrupts the maturation of autophagosomes into functional autolysosomes ( Yang et al., 2013). The oncogene, Akt, negatively regulates autophagy by positively regulating the activity of the mTORC1 complex ( Levine, 2006; Guertin and Sabatini, 2007). p66^Shc deficiency mitigates but does not completely inhibit low-nutrient-induced autophagy in lung cancer A549 cells ( Zheng et al., 2013). This requires prolonged activation of ERK1/2 (Thr202/Tyr204) but not of phosphorylated Akt1 (Ser473) ( Zheng et al., 2013). p66^Shc is necessary to promote autophagosome formation rather than reducing the autophagosome-lysosome fusion ( Zheng et al., 2013). Oncogenic Ras negatively regulates autophagy ( Levine, 2006). Ras signaling can also exert proneoplastic effects through the downregulation of Beclin1, thus suppressing autophagy ( Yoo et al., 2010). The loss of p66^Shc in lung tumor cells leads to unrestrained Ras activation ( Ma et al., 2010; Zheng et al., 2013). Therefore, K-Ras may be involved in p66^Shc-dependent autophagy in nutrient-poor conditions. In nutrient-deprived A549 cells, knockdown of p66^Shc decreases LC3B-I to-II conversion, the number of autophagic vacuoles, and p62/sequestosome 1 protein degradation ( Zheng et al., 2013). In addition, p66^Shc depletion mitigates the process of autophagy induced by ECM detachment; however, the exact mechanism has not been characterized. In addition to its functions in tumor cells, p66^Shc can function as a discrete but essential mediator of metabolic tone and autophagosome formation in neurons. p66^Shc-mediated autophagy acts as an adaptive mechanism to promote the removal of injured neuronal organelles following low level oxygen and glucose deprivation ( Brown et al., 2010).

Future directions and perspectives

The expression of p66^Shc varies in different types of solid tumors. In steroid-induced epithelial cancer cells, p66^Shc protein levels are elevated; whereas, p66^Shc protein levels are decreased in human lung cancers. This difference may result from the different functions of p66^Shc in tumor cells. Although the mechanisms that underlie p66^Shc involvement in tumor progression, anoikis and autophagy in tumor cell have been investigated (Fig. 2), the exact mechanisms and upstream regulators and downstream effectors of p66^Shc functional pathways warrant further investigation.

Nevertheless, these paradoxical properties of p66^Shc make it a novel prognostic and therapeutic target for preventing tumor progression and metastasis. For example, cPAcP, which is a biomarker of PCa and which inhibits tumor cell growth, is inactivated by ROS produced by p66^Shc. Thus, reducing p66^Shc protein by upregulating its ubiquitination is a potential therapeutic approach to inhibit PCa cell proliferation. Conversely, Aiolos, a transcription factor, alters the chromatin structure surrounding the SHC1 gene and silences the expression of p66^Shc, which functions as a metastasis suppressor. Thus, in this case, reactivation of p66^Shc by regulating Aiolos-p66^Shc interactions may be a candidate therapeutic approach for metastatic lung cancer.

Compliance with ethics guidelines

Yanan Sun, Jie Yang and Zhenyi Ma declare that they have no conflicts of interest.

This manuscript is a review article and therefore does not require the approval of the relevant institute review board or ethics committee.

References

[1] Abdollahi A, Gruver B N, Patriotis C, Hamilton T C (2003). Identification of epidermal growth factor-responsive genes in normal rat ovarian surface epithelial cells. Biochem Biophys Res Commun, 307(1): 188–197

[2] Alam S M, Rajendran M, Ouyang S, Veeramani S, Zhang L, Lin M F (2009). A novel role of Shc adaptor proteins in steroid hormone-regulated cancers. Endocr Relat Cancer, 16(1): 1–16

[3] Almeida M, Han L, Ambrogini E, Bartell S M, Manolagas S C (2010). Oxidative stress stimulates apoptosis and activates NF-kappaB in osteoblastic cells via a PKCbeta/p66shc signaling cascade: counter regulation by estrogens or androgens. Mol Endocrinol, 24(10): 2030–2037

[4] Banerjee P, Basu A, Wegiel B, Otterbein L E, Mizumura K, Gasser M, Waaga-Gasser A M, Choi A M, Pal S (2012). Heme oxygenase-1 promotes survival of renal cancer cells through modulation of apoptosis- and autophagy-regulating molecules. J Biol Chem, 287(38): 32113–32123

[5] Bhat H F, Baba R A, Adams M E, Khanday F A (2014). Role of SNTA1 in Rac1 activation, modulation of ROS generation, and migratory potential of human breast cancer cells. Br J Cancer, 110(3): 706–714

[6] Borkowska A, Knap N, Antosiewicz J (2013). Diallyl trisulfide is more cytotoxic to prostate cancer cells PC-3 than to noncancerous epithelial cell line PNT1A: a possible role of p66Shc signaling axis. Nutr Cancer, 65(5): 711–717

[7] Brown J E, Zeiger S L, Hettinger J C, Brooks J D, Holt B, Morrow J D, Musiek E S, Milne G, McLaughlin B (2010). Essential role of the redox-sensitive kinase p66shc in determining energetic and oxidative status and cell fate in neuronal preconditioning. J Neurosci, 30(15): 5242–5252

[8] Chen C S, Mrksich M, Huang S, Whitesides G M, Ingber D E (1997). Geometric control of cell life and death. Science, 276(5317): 1425–1428

[9] Chen X, Yang C S (2001). Esophageal adenocarcinoma: a review and perspectives on the mechanism of carcinogenesis and chemoprevention. Carcinogenesis, 22(8): 1119–1129

[10] Deffieu M, Bhatia-Kissová I, Salin B, Galinier A, Manon S, Camougrand N (2009). Glutathione participates in the regulation of mitophagy in yeast. J Biol Chem, 284(22): 14828–14837

[11] Du W, Jiang Y, Zheng Z, Zhang Z, Chen N, Ma Z, Yao Z, Terada L, Liu Z (2013). Feedback loop between p66(Shc) and Nrf2 promotes lung cancer progression. Cancer Lett, 337(1): 58–65

[12] Faisal A, el-Shemerly M, Hess D, Nagamine Y (2002). Serine/threonine phosphorylation of ShcA. Regulation of protein-tyrosine phosphatase-pest binding and involvement in insulin signaling. J Biol Chem, 277(33): 30144–30152

[13] Foschi M, Franchi F, Han J, La Villa G, Sorokin A (2001). Endothelin-1 induces serine phosphorylation of the adaptor protein p66Shc and its association with 14-3-3 protein in glomerular mesangial cells. J Biol Chem, 276(28): 26640–26647

[14] Francia P, delli Gatti C, Bachschmid M, Martin-Padura I, Savoia C, Migliaccio E, Pelicci P G, Schiavoni M, Lüscher T F, Volpe M, Cosentino F (2004). Deletion of p66shc gene protects against age-related endothelial dysfunction. Circulation, 110(18): 2889–2895

[15] Frisch S M, Francis H (1994). Disruption of epithelial cell-matrix interactions induces apoptosis. J Cell Biol, 124(4): 619–626

[16] Frisch S M, Vuori K, Ruoslahti E, Chan-Hui P Y (1996). Control of adhesion-dependent cell survival by focal adhesion kinase. J Cell Biol, 134(3): 793–799

[17] Galimov E R, Chernyak B V, Sidorenko A S, Tereshkova A V, Chumakov P M (2014). Prooxidant properties of p66shc are mediated by mitochondria in human cells. PLoS ONE, 9(3): e86521

[18] Gilmore A P (2005). Anoikis. Cell Death Differ, 12(Suppl 2): 1473–1477

[19] Giorgio M, Migliaccio E, Orsini F, Paolucci D, Moroni M, Contursi C, Pelliccia G, Luzi L, Minucci S, Marcaccio M, Pinton P, Rizzuto R, Bernardi P, Paolucci F, Pelicci P G (2005). Electron transfer between cytochrome c and p66Shc generates reactive oxygen species that trigger mitochondrial apoptosis. Cell, 122(2): 221–233

[20] Grossman S R, Lyle S, Resnick M B, Sabo E, Lis R T, Rosinha E, Liu Q, Hsieh C C, Bhat G, Frackelton A R Jr, Hafer L J (2007). p66 Shc tumor levels show a strong prognostic correlation with disease outcome in stage IIA colon cancer. Clin Cancer Res, 13(19): 5798–5804

[21] Guertin D A, Sabatini D M (2007). Defining the role of mTOR in cancer. Cancer Cell, 12(1): 9–22

[22] Henderson B E, Feigelson H S (2000). Hormonal carcinogenesis. Carcinogenesis, 21(3): 427–433

[23] Jackson J G, Yoneda T, Clark G M, Yee D (2000). Elevated levels of p66 Shc are found in breast cancer cell lines and primary tumors with high metastatic potential. Clin Cancer Res, 6(3): 1135–1139

[24] Khanday F A, Yamamori T, Mattagajasingh I, Zhang Z, Bugayenko A, Naqvi A, Santhanam L, Nabi N, Kasuno K, Day B W, Irani K (2006). Rac1 leads to phosphorylation-dependent increase in stability of the p66shc adaptor protein: role in Rac1-induced oxidative stress. Mol Biol Cell, 17(1): 122–129

[25] Kilpinen S, Autio R, Ojala K, Iljin K, Bucher E, Sara H, Pisto T, Saarela M, Skotheim R I, Björkman M, Mpindi J P, Haapa-Paananen S, Vainio P, Edgren H, Wolf M, Astola J, Nees M, Hautaniemi S, Kallioniemi O (2008). Systematic bioinformatic analysis of expression levels of 17,330 human genes across 9,783 samples from 175 types of healthy and pathological tissues. Genome Biol, 9(9): R139

[26] Lee M S, Igawa T, Chen S J, Van Bemmel D, Lin J S, Lin F F, Johansson S L, Christman J K, Lin M F (2004). p66Shc protein is upregulated by steroid hormones in hormone-sensitive cancer cells and in primary prostate carcinomas. Int J Cancer, 108(5): 672–678

[27] Levine B (2006). Unraveling the role of autophagy in cancer. Autophagy, 2(2): 65–66

[28] Levine B (2007). Cell biology: autophagy and cancer. Nature, 446(7137): 745–747

[29] Li X, Gao D, Wang H, Li X, Yang J, Yan X, Liu Z, Ma Z (2015). Negative feedback loop between p66Shc and ZEB1 regulates fibrotic EMT response in lung cancer cells. Cell Death Dis, 6: e1708

[30] Li X, Xu Z, Du W, Zhang Z, Wei Y, Wang H, Zhu Z, Qin L, Wang L, Niu Q, Zhao X, Girard L, Gong Y, Ma Z, Sun B, Yao Z, Minna J D, Terada L S, Liu Z (2014). Aiolos promotes anchorage independence by silencing p66Shc transcription in cancer cells. Cancer Cell, 25(5): 575–589

[31] Li Y, Zhang Q, Tian R, Wang Q, Zhao J J, Iglehart J D, Wang Z C, Richardson A L (2011). Lysosomal transmembrane protein LAPTM4B promotes autophagy and tolerance to metabolic stress in cancer cells. Cancer Res, 71(24): 7481–7489

[32] Lin M F, Lee M S, Zhou X W, Andressen J C, Meng T C, Johansson S L, West W W, Taylor R J, Anderson J R, Lin F F (2001). Decreased expression of cellular prostatic acid phosphatase increases tumorigenicity of human prostate cancer cells. J Urol, 166(5): 1943–1950

[33] Lin M F, Meng T C (1996). Tyrosine phosphorylation of a 185 kDa phosphoprotein (pp185) inversely correlates with the cellular activity of human prostatic acid phosphatase. Biochem Biophys Res Commun, 226(1): 206–213

[34] Luzi L, Confalonieri S, Di Fiore P P, Pelicci P G (2000). Evolution of Shc functions from nematode to human. Curr Opin Genet Dev, 10(6): 668–674

[35] Ma Z, Liu Z, Wu R F, Terada L S (2010). p66(Shc) restrains Ras hyperactivation and suppresses metastatic behavior. Oncogene, 29(41): 5559–5567

[36] Ma Z, Myers D P, Wu R F, Nwariaku F E, Terada L S (2007). p66Shc mediates anoikis through RhoA. J Cell Biol, 179(1): 23–31

[37] Mailleux A A, Overholtzer M, Schmelzle T, Bouillet P, Strasser A, Brugge J S (2007). BIM regulates apoptosis during mammary ductal morphogenesis, and its absence reveals alternative cell death mechanisms. Dev Cell, 12(2): 221–234

[38] Malhotra A, Vashistha H, Yadav V S, Dube M G, Kalra S P, Abdellatif M, Meggs L G (2009). Inhibition of p66ShcA redox activity in cardiac muscle cells attenuates hyperglycemia-induced oxidative stress and apoptosis. Am J Physiol Heart Circ Physiol, 296(2): H380–H388

[39] Martin M J, Melnyk N, Pollard M, Bowden M, Leong H, Podor T J, Gleave M, Sorensen P H (2006). The insulin-like growth factor I receptor is required for Akt activation and suppression of anoikis in cells transformed by the ETV6-NTRK3 chimeric tyrosine kinase. Mol Cell Biol, 26(5): 1754–1769

[40] Migliaccio E, Giorgio M, Mele S, Pelicci G, Reboldi P, Pandolfi P P, Lanfrancone L, Pelicci P G (1999). The p66shc adaptor protein controls oxidative stress response and life span in mammals. Nature, 402(6759): 309–313

[41] Migliaccio E, Mele S, Salcini A E, Pelicci G, Lai K M, Superti-Furga G, Pawson T, Di Fiore P P, Lanfrancone L, Pelicci P G (1997). Opposite effects of the p52shc/p46shc and p66shc splicing isoforms on the EGF receptor-MAP kinase-fos signalling pathway. EMBO J, 16(4): 706–716

[42] Mohan N, Banik N L, Ray S K (2011). Combination of N-(4-hydroxyphenyl) retinamide and apigenin suppressed starvation-induced autophagy and promoted apoptosis in malignant neuroblastoma cells. Neurosci Lett, 502(1): 24–29

[43] Morgan B, Sun L, Avitahl N, Andrikopoulos K, Ikeda T, Gonzales E, Wu P, Neben S, Georgopoulos K (1997). Aiolos, a lymphoid restricted transcription factor that interacts with Ikaros to regulate lymphocyte differentiation. EMBO J, 16(8): 2004–2013

[44] Muniyan S, Chou Y W, Tsai T J, Thomes P, Veeramani S, Benigno B B, Walker L D, McDonald J F, Khan S A, Lin F F, Lele S M, Lin M F (2015). p66Shc longevity protein regulates the proliferation of human ovarian cancer cells. Mol Carcinog, 54(8): 618–631

[45] Napoli C, Martin-Padura I, de Nigris F, Giorgio M, Mansueto G, Somma P, Condorelli M, Sica G, De Rosa G, Pelicci P (2003). Deletion of the p66Shc longevity gene reduces systemic and tissue oxidative stress, vascular cell apoptosis, and early atherogenesis in mice fed a high-fat diet. Proc Natl Acad Sci USA, 100(4): 2112–2116

[46] Nemoto S, Finkel T (2002). Redox regulation of forkhead proteins through a p66shc-dependent signaling pathway. Science, 295(5564): 2450–2452

[47] Nobes C D, Hall A (1995). Rho, rac, and cdc42 GTPases regulate the assembly of multimolecular focal complexes associated with actin stress fibers, lamellipodia, and filopodia. Cell, 81(1): 53–62

[48] Northey J J, Chmielecki J, Ngan E, Russo C, Annis M G, Muller W J, Siegel P M (2008). Signaling through ShcA is required for transforming growth factor beta- and Neu/ErbB-2-induced breast cancer cell motility and invasion. Mol Cell Biol, 28(10): 3162–3176

[49] Orsini F, Migliaccio E, Moroni M, Contursi C, Raker V A, Piccini D, Martin-Padura I, Pelliccia G, Trinei M, Bono M, Puri C, Tacchetti C, Ferrini M, Mannucci R, Nicoletti I, Lanfrancone L, Giorgio M, Pelicci P G (2004). The life span determinant p66Shc localizes to mitochondria where it associates with mitochondrial heat shock protein 70 and regulates trans-membrane potential. J Biol Chem, 279(24): 25689–25695

[50] Pattingre S, Bauvy C, Codogno P (2003). Amino acids interfere with the ERK1/2-dependent control of macroautophagy by controlling the activation of Raf-1 in human colon cancer HT-29 cells. J Biol Chem, 278(19): 16667–16674

[51] Pelicci G, Giordano S, Zhen Z, Salcini A E, Lanfrancone L, Bardelli A, Panayotou G, Waterfield M D, Ponzetto C, Pelicci P G,  (1995). The motogenic and mitogenic responses to HGF are amplified by the Shc adaptor protein. Oncogene, 10(8): 1631–1638 

[52] Pelicci G, Lanfrancone L, Grignani F, McGlade J, Cavallo F, Forni G, Nicoletti I, Grignani F, Pawson T, Pelicci P G (1992). A novel transforming protein (SHC) with an SH2 domain is implicated in mitogenic signal transduction. Cell, 70(1): 93–104

[53] Pellegrini M, Pacini S, Baldari C T (2005). p66SHC: the apoptotic side of Shc proteins. Apoptosis, 10(1): 13–18

[54] Re F, Zanetti A, Sironi M, Polentarutti N, Lanfrancone L, Dejana E, Colotta F (1994). Inhibition of anchorage-dependent cell spreading triggers apoptosis in cultured human endothelial cells. J Cell Biol, 127(2): 537–546

[55] Sakai H, Igawa T, Saha P K, Nomata K, Yushita Y, Kanetake H, Saito Y (1992). A case of prostatic carcinoma presenting as a metastatic orbital tumor. Hinyokika Kiyo, 38(1): 77–80 

[56] Shen N, Tsao B P (2004). Current advances in the human lupus genetics. Curr Rheumatol Rep, 6(5): 391–398

[57] Stevenson L E, Frackelton A R Jr (1998). Constitutively tyrosine phosphorylated p52 Shc in breast cancer cells: correlation with ErbB2 and p66 Shc expression. Breast Cancer Res Treat, 49(2): 119–128

[58] Thompson E C, Cobb B S, Sabbattini P, Meixlsperger S, Parelho V, Liberg D, Taylor B, Dillon N, Georgopoulos K, Jumaa H, Smale S T, Fisher A G, Merkenschlager M (2007). Ikaros DNA-binding proteins as integral components of B cell developmental-stage-specific regulatory circuits. Immunity, 26(3): 335–344

[59] Trinei M, Migliaccio E, Bernardi P, Paolucci F, Pelicci P, Giorgio M (2013). p66Shc, mitochondria, and the generation of reactive oxygen species. Methods Enzymol, 528: 99–110

[60] Varma M, Morgan M, O’Rourke D, Jasani B (2004). Prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) immunoreactivity in benign seminal vesicleduct epithelium: a potential pitfall in the diagnosis of prostate cancer in needle biopsy specimens. Histopathology, 44(4): 405–406

[61] Veeramani S, Chou Y W, Lin F C, Muniyan S, Lin F F, Kumar S, Xie Y, Lele S M, Tu Y, Lin M F (2012). Reactive oxygen species induced by p66Shc longevity protein mediate nongenomic androgen action via tyrosine phosphorylation signaling to enhance tumorigenicity of prostate cancer cells. Free Radic Biol Med, 53(1): 95–108

[62] Veeramani S, Igawa T, Yuan T C, Lin F F, Lee M S, Lin J S, Johansson S L, Lin M F (2005a). Expression of p66(Shc) protein correlates with proliferation of human prostate cancer cells. Oncogene, 24(48): 7203–7212

[63] Veeramani S, Yuan T C, Chen S J, Lin F F, Petersen J E, Shaheduzzaman S, Srivastava S, MacDonald R G, Lin M F (2005b). Cellular prostatic acid phosphatase: a protein tyrosine phosphatase involved in androgen-independent proliferation of prostate cancer. Endocr Relat Cancer, 12(4): 805–822

[64] Veeramani S, Yuan T C, Lin F F, Lin M F (2008). Mitochondrial redox signaling by p66Shc is involved in regulating androgenic growth stimulation of human prostate cancer cells. Oncogene, 27(37): 5057–5068

[65] Wang J H, Avitahl N, Cariappa A, Friedrich C, Ikeda T, Renold A, Andrikopoulos K, Liang L, Pillai S, Morgan B A, Georgopoulos K (1998). Aiolos regulates B cell activation and maturation to effector state. Immunity, 9(4): 543–553

[66] Webster M A, Hutchinson J N, Rauh M J, Muthuswamy S K, Anton M, Tortorice C G, Cardiff R D, Graham F L, Hassell J A, Muller W J (1998). Requirement for both Shc and phosphatidylinositol 3′ kinase signaling pathways in polyomavirus middle T-mediated mammary tumorigenesis. Mol Cell Biol, 18(4): 2344–2359

[67] Wirawan E, Vanden Berghe T, Lippens S, Agostinis P, Vandenabeele P (2012). Autophagy: for better or for worse. Cell Res, 22(1): 43–61

[68] Xiao D, Singh S V (2010). p66Shc is indispensable for phenethyl isothiocyanate-induced apoptosis in human prostate cancer cells. Cancer Res, 70(8): 3150–3158

[69] Xie Y, Hung M C (1996). p66Shc isoform down-regulated and not required for HER-2/neu signaling pathway in human breast cancer cell lines with HER-2/neu overexpression. Biochem Biophys Res Commun, 221(1): 140–145

[70] Yang J, Zheng Z, Yan X, Li X, Liu Z, Ma Z (2013). Integration of autophagy and anoikis resistance in solid tumors. Anat Rec (Hoboken), 296(10): 1501–1508

[71] Yoo  B  H,  Wu  X,  Li  Y,  Haniff  M,  Sasazuki  T,  Shirasawa  S, Eskelinen E L, Rosen K V (2010). Oncogenic ras-induced down-regulation of autophagy mediator Beclin-1 is required for malignant transformation of intestinal epithelial cells. J Biol Chem, 285(8): 5438–5449

[72] Zheng Z, Yang J, Zhao D, Gao D, Yan X, Yao Z, Liu Z, Ma Z (2013). Downregulated adaptor protein p66(Shc) mitigates autophagy process by low nutrient and enhances apoptotic resistance in human lung adenocarcinoma A549 cells. FEBS J, 280(18): 4522–4530

RIGHTS & PERMISSIONS

Higher Education Press and Springer-Verlag Berlin Heidelberg