Oncogenic KRAS-Induced Protein Signature in the Tumor Secretome Identifies Laminin-C2 and Pentraxin-3 as Useful Biomarkers for the Early Diagnosis of Pancreatic Cancer

SIMPLE SUMMARY: Pancreatic ductal adenocarcinoma is an aggressive neoplasia that responds poorly to treatments and is frequently recognized at advanced stages. Early diagnosis and the possibility to undergo resective surgery would increase the rate of patient survival and the chance of a definitive cure. In search of candidate biomarkers to improve laboratory tests for early diagnosis, we have characterized the proteins secreted by pancreatic cells expressing the oncogene KRAS(G12V). Of several upregulated proteins, the expression of seven proteins was quantified in tumors of surgically resected patients. For two of these proteins, Laminin-C2 and Pentraxin-3, the plasma levels were significantly higher in patients than in healthy donors, and their good laboratory performance makes them two promising biomarkers of pancreatic cancer. ABSTRACT: KRAS mutations characterize pancreatic cell transformation from the earliest stages of carcinogenesis, and are present in >95% of pancreatic ductal adenocarcinoma (PDAC) cases. In search of novel biomarkers for the early diagnosis of PDAC, we identified the proteins secreted by the normal human pancreatic cell line (HPDE) recently transformed by inducing the overexpression of the KRAS(G12V) oncogene. We report a proteomic signature of KRAS-induced secreted proteins, which was confirmed in surgical tumor samples from resected PDAC patients. The putative diagnostic performance of three candidates, Laminin-C2 (LAMC2), Tenascin-C (TNC) and Pentraxin-3 (PTX3), was investigated by ELISA quantification in two cohorts of PDAC patients (n = 200) eligible for surgery. Circulating levels of LAMC2, TNC and PTX3 were significantly higher in PDAC patients compared to the healthy individuals (p < 0.0001). The Receiver Operating Characteristics (ROC) curve showed good sensitivity (1) and specificity (0.63 and 0.85) for LAMC2 and PTX3, respectively, but not for TNC, and patients with high levels of LAMC2 had significantly shorter overall survival (p = 0.0007). High levels of LAMC2 and PTX3 were detected at early stages (I–IIB) and in CA19-9-low PDAC patients. In conclusion, pancreatic tumors release LAMC2 and PTX3, which can be quantified in the systemic circulation, and may be useful in selecting patients for further diagnostic imaging.