TGF-beta signalling pathway factors in HPV-induced cervical lesions

Human papillomaviruses (HPV) are considered the etiological agents of cervical cancer, especially high-risk genotypes. TGF-beta (transforming growth factor-beta) is well known for its anti-proliferative effects but the neoplastic cells often lose their sensitivity to TGF-beta. A characteristic alteration associated with malignant progression is the loss of responsiveness to TGF-beta1-induced cell growth inhibition. The aim of the present study was to establish the possible role of some members of TGF-beta signalling pathway during cervical cancer development and the possible relationship with HPV infection. In order to establish TGF-beta gene expression levels in cervical oncogenesis, TGF-beta1, TGF-beta1 receptors and Smad2 were investigated in precancerous and cervical cancer samples (Quantitative Real-Time PCR). The study revealed that 84.5% of patients were positive for HPV DNA. The most prevalent HPV genotypes were high-risk HPV 16 and 18 in single or co-infections. Expression of TGF-beta1 decreased as tumor cells progressed from cervical intraepithelial neoplasia to cervical carcinoma. Furthermore, we observed that cervical lesions without HPV infection expressed significantly less TGF-beta1. TGF-betaRI and Smad2 gene expression levels were found to be decreased in SCC and AC samples in contrast with CIN1 and CIN2/3 samples. Our results showed that in human cervical cancer the disruption of TGF-beta/Smad signalling pathway might contribute to the malignant progression of cervical dysplasia. These data emphasize the importance of canonical TGF-beta pathway integrity in carcinogenesis.