iTRAQ-based quantitative proteomics reveals myoferlin as a novel prognostic predictor in pancreatic adenocarcinoma

Histological differentiation is a major pathological parameter associated with poor prognosis in patients with pancreatic adenocarcinoma (PAC) and the molecular signature underlying PAC differentiation may involve key proteins potentially affecting the malignant characters of PAC. We aimed to identify the proteins which could be implicated in PAC prognosis. We used isobaric tags for relative and absolute quantitation (iTRAQ) coupled with two-dimensional liquid chromatography-tandem mass spectrometry to compare protein expression in PAC tissues with different degrees of histological differentiation. A total of 1623 proteins were repeatedly identified by performing the iTRAQ-based experiments twice. Of these, 15 proteins were differentially expressed according to our defined criteria. Myoferlin (MYOF) was selected to validate the proteomic results by western blotting. Immunohistochemistry in a further 154 PAC cases revealed that myoferlin significantly correlated with the degree of histological differentiation (P=0.004), and univariate and multivariate analyses indicated that MYOF is an independent prognostic factor for survival (hazard ratio, 1.540; 95% confidence interval, 1.061-2.234; P=0.023) of patients with PAC after curative surgery. RNA interference-mediated knockdown of MYOF alleviated malignant phenotypes of both primary and metastatic PAC cell lines in vitro and in vivo. Thus, ITRAQ-based quantitative proteomics revealed the prognostic value of MYOF in PAC.

Our results provide the possibility of novel strategies for pancreatic adenocarcinoma management.