Synergistic effect of the herbal mixture C5E on gemcitabine treatment in PANC-1 cells

The present study aimed to determine the anticancer effect of the herbal mixture extract C5E in the pancreatic cancer cell line, PANC-1, in the absence or presence of gemcitabine treatment, a chemotherapeutic drug used for the treatment of pancreatic cancer. The anticancer effects of C5E, gemcitabine and C5E plus gemcitabine in PANC-1 cells following 72 h of treatment were investigated. The effect of each treatment on cell cycle arrest, apoptosis and the proportion of side population (SP) cells was determined using flow cytometric analysis following propidium iodide (PI), Annexin V-FITC/PI double staining and Hoechst 33342 staining, respectively. SP cells share similar characteristics to cancer stem-like cells, and a reduction in the SP is considered to be indicative of an anticancer effect. The percentage of SP cells and the cell viability of general PANC-1 cells were significantly decreased in response to all treatments. The percentage of SP cells was reduced from 8.2% (control) to 3.9, 7.2 and 5.1% following the treatment with C5E, gemcitabine and the co-treatment, respectively. All three treatments were discovered to inhibit cell viability by arresting the cell cycle at the S phase and promoted cell death by inducing early apoptosis, with the levels of apoptosis being increased from 1.9% (control) to 7.3, 2.5 and 12.0% following the treatment with C5E, gemcitabine and the co-treatment, respectively. The mRNA expression levels of sonic hedgehog, which is implicated in the development of certain types of cancer, were downregulated to a greater extent following the co-treatment with C5E and gemcitabine compared with the treatment with either C5E or gemcitabine alone. As the co-treatment with gemcitabine and C5E was more effective than each individual treatment, the present study suggested that the combined treatment may exhibit synergistic effects in PANC-1 cells.