Abstract 1121: Role of c-Met in colorectal cancer lung metastasis

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the US; systemic metastasis to the lungs occurs in approximately 10-20% of patients with CRC. Hepatocyte growth factor (HGF) and its tyrosine kinase receptor Met play a pivotal role in the tumor metastatic phenotype and represent attractive therapeutic targets. The present study was designed to determine the role of c-Met in growth and metastasis of CRC cells to the lung. We evaluated patient-derived xenografts (PDX) tumors and CRC cells for c-Met activation (phospho-Met [Tyr1234/1235]), established PDX cell lines with high phospho-Met (Tyr1234/1235) expression from lung or liver metastases, and investigated the role of c-Met expression in CRC lung metastasis. Methods. (1) PDX tumors were implanted into NOD-scid IL2Rgammanull mice; PDX cell lines were established from F3 tumor generation. (2) The protein expression of phospho-Met (Tyr1234/1235) was observed by western blotting and immunohistochemistry. (3). HT29 LungM3 cell line was derived from the human CRC line HT29 following multiple rounds of in vivo selection for lung metastasis in immunodeficient mice. HT29LungM3 cells were transfected with shRNA expression vectors targeting the c-Met gene. HT29LungM3 cells were injected into SCID mice subcutaneously to measure tumor growth or intravenously to examine the role of c-Met in CRC lung metastasis. Results. (1) High phospho-Met (Tyr1234/1235) expression was identified in 6 out of 20 CRC PDX models. Two PDX cell lines with high phospho-Met (Tyr1234/1235) expression, 2377LM (from liver metastasis) and 2387 (from lung metastasis), were established. Metastatic potential of the 2377LM cell line to the liver was confirmed after intrasplenic injection of cancer cells into SCID mice. The metastatic potential of 2387 cells to the lung was confirmed after intravenous injection of cancer cells into SCID mice. (2) Western blot analysis demonstrated high phospho-Met (Tyr1234/1235) expression in HT29LungM3, 2387LM and 2387 cell lines, compared to HCT116 (human CRC), LS174T (human CRC), Caco-2 (human CRC), SK-OV-3 (human ovarian cancer) and JAR (placenta choriocarcinoma) cell lines. (3) HT29LungM3 cells were transfected with shRNA expression vectors targeting the c-Met gene with c-Met knockdown of at least 90%. Surprisingly, c-Met inhibition in the HT29LungM3 cell line had no effect on subcutaneous tumor growth or lung metastasis. Conclusions. Aberrant expression of c-Met is associated with the progression of multiple human malignancies and has been identified as a novel target for the treatment of malignant tumors. Here, we examined expression of phospho-Met (Ty1234/1235) in CRC PDX cell samples and determined that c-Met knockdown does not decrease CRC lung metastasis. These results are important for understanding the mechanism of CRC lung metastasis and proper strategy selection for prevention and treatment of patients with advanced disease. Citation Format: Piotr G. Rychahou, Nick Roller, Eun Y. Lee, Nicole Rychagov, Matthew Melton, Carrigan Wasilchenko, B. Mark Evers. Role of c-Met in colorectal cancer lung metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1121.