1. Role of CYB5A in Pancreatic Cancer Prognosis and Autophagy Modulation.
- Author
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Giovannetti, Elisa, Qiuyan Wang, Avan, Amir, Funel, Niccola, Lagerweij, Tonny, Jih-Hsiang Lee, Caretti, Viola, van der Velde, Arjan, Boggi, Ugo, Yisong Wang, Vasile, Enrico, Peters, Godefridus J., Wurdinger, Thomas, and Giaccone, Giuseppe
- Subjects
CANCER prognosis ,PANCREATIC cancer ,AUTOPHAGY ,VESICLES (Cytology) ,GENE silencing - Abstract
Background Loss of 18q22.3 is a prognostic marker in pancreatic ductal adenocarcinoma (PDAC). This study investigated genes encoded by this cytoband. Methods We studied mRNA/protein expression in radically resected (n = 130) and metastatic patients (n = 50).The role of CYB5A was tested in 11 PDAC cell lines and five primary cultures through retrovirus-mediated upregulation and small interfering RNA using wound-healing, invasion, annexin-V, electron microscopy, and autophagic assays, as well as autophagy genes and kinases arrays. CYB5A+ orthotopic models (n = 6 mice/group) were monitored by Firefly and Gaussia-luciferase bioluminescence, magnetic resonance imaging, and high-frequency ultrasound. Data were analyzed by f test, Fisher exact-test, log-rank test and Cox proportional hazards models. All statistical tests were two-sided. Results Both resected and metastatic patients with low mRNA or protein expression of CYB5A had statistically significantly shorter survival (eg, median = 16.7 months, 95% confidence interval [CI] = 13.5 to 19.9; vs median = 24.8 months, 95% CI = 12.8 to 36.9; P = .02, two-sided log-rank test; n = 82 radically resected PDACs), and multivariable analyses confirmed prognostic relevance. Moreover, we characterized a novel function to CYB5A, autophagy induction, concomitant with reduced proliferation and migration/invasion of PDAC cells. Network analysis of proautophagic pathways suggested CYB5A interaction withTRAF6, which was confirmed byTRAF6 downregulation after CYB5A reconstitution (-69% in SU.86.86-CYB5A+; P= .005, two-sided f test). CYB5A silencing had opposite effects, restoring TRAF6 expression and wound healing. In vivo studies showed that CYB5A induced autophagy while inhibiting tumor growth/metastasis and increasing survival (median = 57 days, 95% CI = 52 to 61; vs median = 44 days, 95% CI = 21 to 57; P= .03, two-sided log-rank test). Conclusions These results define CYB5A as a novel prognostic factor for PDAC that exerts its tumor-suppressor function through autophagy induction andTRAF6 modulation. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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