Effect of chemotherapeutic stress on induction of VEGF family members in human colorectal cancer cells

AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA 2083 Introduction: Vascular endothelial growth factor (VEGF) and its receptors play a central role in human colorectal cancer (CRC) angiogenesis, progression, and metastasis. The effect of stress, such as hypoxia and cell density, on VEGF induction is well characterized. In addition, we recently demonstrated the presence and function of VEGF receptor-1 (VEGFR-1) on human CRC cells. We sought to determine if another mediator of cell stress, chemotherapy, could also induce VEGF and VEGFRs expression and production on CRC cells. Methods: The human CRC cell lines HT29 and HCT-116 were exposed to various concentrations of Oxaliplatin (0-10uM) for 2, 6, and 24 hours in vitro. VEGF-A mRNA was determined by Northern blot analysis; VEGFR-2 and -3 expression was determined by RT-PCR; and VEGF-C, VEGFR-1, and NRP-1, -2 levels were determined by Western blot analysis. The effect of oxaliplatin on VEGF-A transcriptional activity was determined using VEGF-A promoter constructs. VEGF-A mRNA half-life was determined by administration of Actinomycin-D either with or without oxaliplatin Results: Acute exposure of human CRC cells to Oxaliplatin led to a marked induction of VEGF-A mRNA through transcriptional activation. The stability of VEGF-A mRNA was not altered by Oxaliplatin. VEGF-C production was increased in the conditioned media of CRC cells treated with Oxaliplatin. Among the VEGF receptors, the production of both VEGFR-1 and NRP-1, a co-receptor for VEGF, was increased by the acute exposure to Oxaliplatin. Oxaliplatin had no effect on NRP-2 expression. VEGFR-2 and -3 were not detected in CRC cells in the presence or absence of Oxaliplatin. Conclusion: Chemotherapy induced stimulation of angiogenic/growth factors production may reflect the adaptive stress responses by which tumor cells attempt to protect themselves from chemotherapy mediated cytotoxicity. Inhibition of such pro-survival responses might represent an important strategy for improvement of the efficacy of cancer therapy.