Genomic Instability Causes HGF Gene Activation in Colon Cancer Cells, Promoting Their Resistance to Necroptosis

Abstract

Background & Aims Genomic instability promotes colon carcinogenesis by inducing genetic mutations, but not all genes affected by this process have been identified. We investigated whether genomic instability in human colorectal cancer (CRC) cells produces mutations in the hepatocyte growth factor (HGF) gene. Methods We genotyped human colon tumor tissues and adjacent non-tumor tissues collected from 78 patients University of Pittsburgh Health Sciences and Veterans hospital, along with 40 human CRC and adjacent non-tumor tissues in a commercial microarray. We used cellular, biochemical, and molecular biological techniques to investigate the factors that alter HGF signaling in colon cancer cells and its effects on cell proliferation and survival. Results All tested human CRC tissues and cell lines that had microsatellite instability (MSI) contained truncations in the regulatory deoxyadenosine tract element (DATE) of the HGF gene promoter. The DATE was unstable in 14% (11/78) of CRC samples; DATE truncation was also polymorphic, and detected in 18% (13/78) of CRC tissues without MSI. In CRC cell lines, truncation of DATE activated expression of HGF, resulting in its autocrine signaling via MET. This promoted cell proliferation and resistance to necroptosis. HGF signaling via MET reduced levels of the receptor-interacting serine-threonine kinase 1 (RIPK1), a mediator of necroptosis, in CRC cells. High levels of HGF protein in tumor tissues correlated with lower levels of RIPK1 and shorter survival times of patients. Conclusions Thirty-one percent of CRC samples contain alterations in the DATE of the HGF promoter. Disruption of the DATE increased HGF signaling via MET and reduced levels of RIPK1 and CRC cell necroptosis. DATE alteration might be used as a prognostic factor or to select patients for therapies that target HGF-MET signaling.

Fibroblast-Specific β-Catenin Signaling Dictates the Outcome of AKI

“…The effect of Wnt/b-catenin on HGF gene transcription was assessed by cotransfecting with pGL3-HGF promoter reporter plasmid (HGF promoter region, 21037 to +56, kindly provided by Dr. Reza Zarnegar at the University of Pittsburgh) or pGL3-Basic vector, 60 and N-terminally truncated, stabilized b-catenin expression vector (pDel-b-cat), by using Lipofectamine 2000 reagent in cultured NRK-49F fibroblasts. An internal control plasmid (0.1 mg) Renilla reniformis luciferase driven under TK promoter (pRL-TK; Promega, Madison, WI) was also cotransfected for normalizing the transfection efficiency.…”

Inhibition of pro-HGF activation by SRI31215, a novel approach to block oncogenic HGF/MET signaling

“…MET mutations (or MET amplification /overexpression) which trigger ligand- independent activation of signaling, are relatively rare in human cancer and occur in approximately 6% of colon cancers [ 11 ]. In contrast, HGF has been recently shown to be produced in a relatively large subset (~30%) of primary colon tumors and established colon cancer cell lines due to mutations in the HGF promoter region [ 12 ]. HGF-producing cancer cells display autocrine activation of MET signaling [ 13 ].…”

Evaluation of Tc-99 m Labeled Dimeric GX1 Peptides for Imaging of Colorectal Cancer Vasculature

“…There is considerable evidence that tumor angiogenesis is different from physiological angiogenesis in a number of ways [25,26]. In contrast to the genetic instability of tumor cells, the genome of tumor-associated endothelial cells is genetically stable [27][28][29]. As a result, drug resistance is less likely to be acquired.…”