Adjuvant therapeutic use of Turmeric Force^TM with Gemcitabine against pancreatic cancer

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Introduction: Pancreatic cancer is the tenth most commonly diagnosed form of cancer among men and women. It accounts for an estimated 2 percent of all new cancer cases and is one of the most lethal forms of human cancers. While pancreatic cancer incidence is the highest in United States (>13 cases per 100,000 persons per year), India has one of the lowest incidence (<2 cases per 100000 persons). Whether the low incidence in India is associated with daily consumption of curcumin-containing turmeric, although suggestive, has not been definitively proven. Turmeric Force™ (TF) is the supercritical CO₂ and hydroethanolic extract of turmeric rhizomes marketed by New Chapter Inc. VT. It contains 45% turmerones, 11% curcuminoids and other molecules that may represent the full potency of turmeric. We have investigated the synergistic effect of TF and gemcitabine in pancreatic adenocarcinoma cell lines in order to develop TF for the treatment of human pancreatic cancers.
 Materials and Methods: Twopancreatic adenocarcinoma cell lines (BXPC3 and Panc-1) were used for the study. Cytotoxicity of TF, gemcitabine and their combination were analyzed using Cell Proliferation kit (MTT). The data were analyzed using CalcuSyn program to determine the additiveness, synergism or antagonism between gemitabine and TF. Flow cytometry analysis was used to determine the drug-induced apoptosis using the Annexin-FLUOS kit (Roche Biochemicals, IN). NF-kB activity and IL-8 expression were analyzed using ELISA kits (Active Motif, CA).
 Results: TF is cytotoxic to both pancreatic cancer cell lines with mean IC₅₀ values of 1.0 µg/ml for BxPC3 and 1.22 µg/ml for Panc-1. TF IC₅₀ value is significantly lower than that of curcumin (3.68 - 5.52 µg/ml). Gemcitabline has an IC₅₀ value of 0.03 µg/ml, although the highest concentration of 50 µg/ml was unable to induce more than 55-60% cell death in BxPC3 and Panc-1. When the cytotoxic data were analyzed by CalcuSyn software, gemcitabine and TF combination showed strong synergism with combination index (CI) values of 0.216 and 0.236 in BxPC3 and Panc-1 cell lines, respectively. Flow cytometric analysis of DNA content using propidium iodide staining showed that TF induced G₂/M block and subG₀/G₁ population in a dose-dependent manner. Both cell cycle blocking and Annexin -V staining confirmed the involvement of apoptosis on the cytotoxic effect of TF in tumor cells. Both gemcitabine and TF down-regulated NF-kB activity and the combination treatment showed higher degree of inhibition than either agent alone, although NF-kB mRNA level remained the same in all treatment groups. NF-kB-regulated IL-8 expression also showed a similar trend.
 Conclusions: TF can be used as a single agent or an adjuvant with gemcitabine for the treatment of pancreatic carcinomas. Since it contains turmerones in addition to curcumin and represents full potency of raw turmeric, TF may be better than curcumin and biologically available.