Sanguinarine-Mediated Sensitization of Cervical Cancer SiHa Cells to TRAIL

Introduction: Cervical cancer is primarily caused by the human papilloma virus (HPV), which transforms normal cervical cells into cancerous cells that are highly resistant to radiation and chemotherapy. Induction of apoptosis in transformed cells is a key strategy in successfully treating HPV-induced cervical cancer. TRAIL (tumor necrosis factor related apoptosis-inducing ligand) has been shown to selectively induce apoptosis in cancer cells by binding to death receptors and activating extrinsic pathways for apoptosis. However, certain cervical cancers—such as the cultured cell line SiHa—are remarkably resistant to TRAIL. In this study, SiHa cells were sensitized to TRAIL by using sanguinarine—derived from the plant Sanguinaria Canadensis—which is known to induce oxidative stress and lead to the upregulation of receptors for TRAIL. Methods: Cultured SiHa cells were exposed to sub-lethal doses of sanguinarine in combination with TRAIL. Cell viability changes as well as the production of reactive oxygen species (ROS) were assessed. The induction of apoptosis was investigated by assays for caspase activation. Flow cytometry was performed to analyze expression of death receptors 4/5. Results: Treatment of SiHa cells with a combination of sanguinarine and TRAIL led to a significant reduction in cell viability. Significant increase in ROS was observed and caspase activation assays confirmed the induction of apoptosis. Conclusions: The observed synergistic effect of sanguinarine and TRAIL on SiHa cells is promising for the treatment of cervical, and possibly other, HPV-induced cancers. Oxidative stress caused by sanguinarine seems to play a central role in this synergy. The precise link between reactive oxygen species and the possible upregulation of death receptors needs further investigation. This knowledge will enable us to devise more effective treatments for those who suffer from this devastating disease.

<i>In Vitro</i>Model Systems to Investigate Drug Resistance Mechanisms in Pancreatic Cancer Cells

With a 5-year survival rate of less than 6%, the diagnosis of pancreatic cancer is devastating news for any patient. Gemcitabine, the most commonly used chemotherapy drug, only improves survival by approximately 1.5 months. A major obstacle to the treatment of pancreatic cancer with gemcitabine is the development of drug resistance. To better understand the precise mechanisms by which patient tumor cells gain resistance to gemcitabine, a cell culture model system that more accurately reflects the development of drug resistance in vivo is required. In this study, cultured pancreatic adenocarcinoma BxPC-3 cells were subjected to two different treatment regimens. The first method—termed pulse method—involves periodically treating separate cultures of BxPC-3 cells with constant predetermined doses of gemcitabine. The second treatment regimen—termed incremental method—consists of treating BxPC-3 cells with increasing doses of gemcitabine from 10 to 100 nM. While all treated cells showed enhanced resistance to gemcitabine, low-dose pulse treatments were sufficient to produce highly drug-resistant cells as evidenced by higher IC50 measurements. Pulse treatments also resulted in slower growth rates and increased doubling time of the drug-resistant cells. Morphological changes indicate cellular abnormalities linked to likely epithelial-to-mesenchymal transition and drug resistance. Our preliminary results indicate that the pulse method may better simulate resistance observed in patients undergoing chemotherapy and may serve as a superior model to investigate drug-resistance. This model can also help with identification of appropriate markers that determine the presence of drug-resistant cells and help clinicians adjust treatment strategies to improve outcomes for patients suffering from pancreatic cancer.