Reducing invasion potential of cervical cancer cells via targeted knockdown of c-Jun.
e22005 Background: Despite recent advent of vaccines for human papillomaviruses (HPV) in cervical cancer and increasing efforts to improve therapy, deaths still average 275,000 annually worldwide, with most women succumbing to recurrent or metastatic disease. The c-Jun oncogene is a subunit of the activating protein-1 (AP-1) transcription factor and is strongly expressed in cervical cancer, regulating the expression of HPV16 and 18 genes. AP-1 plays a major role in cell growth, migration and apoptosis in many cell types. This study examined the role of c-Jun in modulating HeLa proliferation, migration, apoptosis and invasion as well as susceptibility to cisplatin. Methods: Transient knockdown and over-expression of c-Jun was performed in HeLa cervical cancer cells using Dharmacon c-Jun siRNA and Origene Jun expression vector. c-Jun and downstream gene/protein expression was confirmed by western blot and real-time PCR and cells subject to proliferation, in vitro wound and matrigel dual-chamber transwell assays. Flow cytometry was used for analysis of cell cycle and apoptosis. Results: c-Jun protein and mRNA levels were reduced by c-Jun siRNA. c-Jun silencing inhibited cervical cancer cell proliferation. Significantly, c-Jun suppression dramatically reduced HeLa migration and invasion and targeted down-regulation of cyclooxygenase-2 (Cox2), interleukin-6 (IL-6), metalloproteinases (MMP)-1, -9 and -13 as well as HPV18 E6 and E7, genes highly expressed in cervical cancer and associated with metastatic growth. Direct siRNA knockdown of Cox2 in HeLa also reduced MMP1 and MMP9 expression suggesting an intermediary link. In HeLa cells over-expressing c-Jun, cell proliferation was not significantly increased but cell invasiveness was markedly enhanced in parallel with enhanced MMP-1 expression. Modulation of c-Jun expression did not interfere with susceptibility of HeLa cells to apoptosis in the presence of cisplatin. Conclusions: Reduced invasion potential of HeLa cells after c-Jun knockdown suggests a potential target in treatment of metastatic and recurrent cervical cancer. Data suggest a mechanism involving down-regulation of Cox2 and MMP-1 and -9 expression.