Riproximin mediated cytotoxicity and expression modifications in lung cancer cells

Background: Worldwide, lung cancer is the leading malignancy and responsible for ~20% of cancer related deaths. Evidence from clinical data shows an objective response from currently available therapeutic approaches, especially against advance stages of lung cancer, which in turn, highlight the need to identify novel treatment modalities with better efficacy and lesser off target effects. A ~60kDa active protein component was purified from of the plant Ximenia american. The purified protein (riproximin) has shown cytotoxic effects over the years against cancer cells and in the animal models. Methods: Effects of riproximin on cell viability were investigated by MTT dye reduction methodology. Briefly, the lung cancer cell line (H1299) was cultured in 96-well plate and treated with different concentrations of riproximin (0.39- 25ng/ml) for three different time points (24, 48 and 72 hours). After each time interval, MTT solution was added, and concentration of viable cells were determined by ELISA plate reader. Later, the impact of riproximin on selective genes were analyzed by real time PCR strategy. The data was compared with the expression profile of untreated control cells, and fold changes were calculated via Livak method. Results: The cytotoxic effects of riproximin were time and concentration dependent as more prominent toxicity was observed with increasing concentrations especially for late time intervals (48 and 72 hours). At highest concentration (25ng/ml), the maximum growth inhibition was observed (85%) after 72 hours. Substantial riproximin mediated expressional modulations in related genes were shown by real time PCR. Specifically, CCND1 and CASP3 genes were inhibited, while SERTAD1 and GADD45A were induced in response to riproximin exposure. Conclusion: Riproximin is a substantial cytotoxic compound and induces prominent anti- proliferative effects in lung cancer cells. Furthermore, the compound has potential to alter the expressional profile of genes. The current study provides vital data about antineoplastic effects of riproximin against lung cancer cells and will provide a platform for further studies and clinical utilization of this protein to treat lung cancer overtime.