Cyclin D1 overexpression associated with activation of STAT3 in oral carcinoma patients from South India

Background: Our previous study showed that overexpression of cyclin D1 protein is associated with poor prognosis in oral squamous cell carcinoma (OSCC) patients. Regarding the alteration in the transactivating pathway regulating cyclin D1 expression is still unclear in OSCC from our population. Objectives: The major objective of this study is to understand the alteration associated with the transactivation pathway regulating the cyclin D1 overexpression in OSCC patients from our population. Materials and Methods: Alteration in the transactivation pathway regulating cyclin D1 expression was evaluated in tumor sample from OSCC patients. The findings were further validated using in vitro knockdown model in OSCC cell line. Results: Results from the patients' samples showed that the Phospho-STAT3 has a significant association with cyclin D1 overexpression in OSCC tumor samples. Further knockdown in vitro studies using SCC66 showed a significant correlation between STAT3 and cyclin D1 in OSCC. Conclusion: The results from this study showed that in our population the cyclin D1 overexpression is associated with hyperactivation of STAT3 pathway. Our previous result has shown that the cyclin D1 protein overexpression is associated with poor prognosis in OSCC patients. Hence, STAT3 pathway will be better target for the patients with increased cyclin D1 in OSCC patients from our population.