Differential expression of IGF-I and insulin receptor isoforms in HPV positive and negative human cervical cancer cell lines.

Human papillomavirus (HPV) is the main risk factor for cervical cancer; however, some carcinomas occur in the absence of the virus. IGF-IR and an isoform of the insulin receptor, IR-A, play important roles in cancer. In this study we assessed the role of the IGF/insulin receptors in cervical cancer cell lines with different HPV status, SiHa (HPV positive), and C33a (HPV negative). Different patterns of receptor expression were found; while SiHa expressed IGF-IR, IR-A and IR-B, and IR/IGF-IR hybrid receptors, C33a cells expressed the IR-A only. Tyrosine phosphorylation of these receptors in response to their corresponding ligands correlated with the expression level of these receptors in the cell lines. Activation of PI3-K and MAPK pathways was revealed in both cell lines, however, no effects on proliferation, migration, or invasion were observed. Here we show that cervical cancer cell lines--positive and negative for HPV--differ in the type of insulin and IGF-1 receptors expressed. Additional studies are needed for characterization of the role of IR-A in cervical carcinogenesis.