Platelet Factor 4: A targetable chemokine induces antineoplastic effects in colorectal cancer cells<sup></sup>

Background: Platelet Factor 4 plays an important role in tumor cell proliferation, migration and invasion. Platelet Factor 4 is an angio-static chemokine that acts as an immunosuppressant in tumor microenvironment by inhibiting T cell mediated anti-tumor immune response. Due to chemoattractant properties, it appears to be an important marker in cancer progression. In this study, Platelet Factor 4 was inhibited in the colorectal cancer cells followed by concomitant effects on functional properties of the colorectal cancer cells. Methods: Platelet Factor 4 gene was knocked down by siRNA in human (Caco2) and rat (CC531) colorectal cancer cells. MTT assay was used to observe colorectal cancer cell survival following the Platelet Factor 4 knockdown, while trans-well migration assay, scratch assay and colony forming assays were used to investigate the ability of colorectal cancer cells to migrate and form colonies respectively. Results: Knockdown of Platelet Factor 4 causes decrease in proliferation of the colorectal cancer cells. Inhibition of the gene also reduced the migration, colony formation and wound healing properties of colorectal cancer cells. The effects were visible and comparable in the human and rat colorectal cancer cell lines. Conclusion: Down-regulation of Platelet Factor 4 gene may serve as a therapeutic target in colorectal cancer.