Potentiation of gemcitabine by Turmeric Force™ in pancreatic cancer cell lines

Abstract

Abstract. Gemcitabine is a first line cancer drug widely used for the treatment of pancreatic cancer. However, its therapeutic efficiency is significantly limited by resistance of pancreatic cancer cells to this and other chemotherapeutic drugs. We have investigated the cytotoxic effect of Turmeric Force™ (TF), a supercritical and hydroethanolic extract of turmeric, alone and in combination with gemcitabine in two pancreatic carcinoma cell lines (BxPC3 and Panc-1). TF is highly cytotoxic to BxPC3 and Panc-1 cell lines with IC 50 values of 1.0 and 1.22 μg/ml, respectively with superior cytotoxicity than curcumin. Gemcitabine IC 50 value for both of these cell line is 0.03 μg/ml; however, 30-48% of the pancreatic cancer cells are resistant to gemcitabine even at concentrations >100 μg/ml. In comparison, TF induced cell death in 96% of the cells at 50 μg/ml. The combination of gemcitabine and TF was synergistic with IC 90 levels achieved in both pancreatic cancer cell lines at lower concentrations. CalcuSyn analysis of cytotoxicity data showed that the Gemcitabine + Turmeric Force combination has strong synergism with combination index (CI) values of 0.050 and 0.183 in BxPC3 and Panc-1 lines, respectively at IC 50 level. This synergistic effect is due to the increased inhibitory effect of the combination on nuclear factor-κ B activity and signal transducer and activator of transcription factor 3 expression as compared to the single agent. IntroductionPancreatic carcinoma is among the most aggressive forms of human cancer with a very high mortality rate. It represents the fourth leading cause of cancer death in United States with an annual mortality of 32,000. With a 5-year survival rate of only 3% and a median survival of <6 months, diagnosis of pancreatic adenocarcinoma carries one of the poorest prognoses of any form of cancer (1,2). Consequently, the management and treatment of this relatively common form of cancer is considered to be a major medical challenge for the 21st century. Pancreatic cancers are difficult to detect and diagnose because in the early stages of the disease, patients are generally asymptomatic or demonstrate signs and symptoms that mimic other more common illnesses (3). Consequently, at the time of diagnosis the disease has typically metastasized making treatment of pancreatic cancer extremely difficult. Chemotherapy alone or as adjuvant to surgery or radiation has not significantly contributed to the cure or prolongation of survival in pancreatic cancer patients (4). Among the recently approved drugs, gemcitabine (GEM) represents an important advance and is the first chemotherapy agent approved on the basis of clinical response instead of the traditional increase in survival time. Therefore, effective therapeutic drugs or drug combinations to improve survival time are yet to be identified.Recent studies indicate that novel strategies for sensitizing pancreatic cancer cells with natural dietary chemopreventive agents would be beneficial for overcoming intrinsic tumor cell resistance (5-8). ...

Curcumin Induces Pancreatic Adenocarcinoma Cell Death Via Reduction of the Inhibitors of Apoptosis

“…In addition, studies by Kunukkamara et al have demonstrated that curcumin attenuates NF-kB activation, resulting in decreased production of anti-apoptotic factors, including Survivin and cIAP1, as well as pro-angiogenic and metastatic factors, in MiaPaCa-2-derived xenograft tumors (69). Multiple studies have demonstrated synergistic activity between curcumin and Gemcitabine in pancreatic adenocarcinoma cells (40-42). Interestingly, while XIAP is considered to be the most potent regulator of apoptosis in humans, its levels following curcumin treatment remain to be elucidated.…”

“…Furthermore, curcumin induces apoptosis in pancreatic cancer (37) and regulates IAP expression in a variety of other cancer types (38-39). Preclinical studies involving curcumin in pancreatic cancer have shown that curcumin enhances Gemcitabine sensitivity in vitro and in vivo (40-42). Moreover, Phase I and II clinical trials have yielded promising results on the use of curcumin as part of pancreatic cancer therapeutic strategies (43-48).…”

Potential applications of curcumin and its novel synthetic analogs and nanotechnology-based formulations in cancer prevention and therapy

“…The intraperitoneal injection of curcumin in corn oil (100 mg/kg/day, each 2 nd day for 18 days) also suppressed the tumor growth of L3.6pL cell xenografted in nude mice [153]. Moreover, curcumin potentiated the anti-proliferative and apoptotic effects induced by gemcitabine, a first-line chemotherapeutic drug, on BxPC-3, Panc-1 and MiaPaCa-2 pancreatic cancer cell lines in vitro [27,154]. A combination of curcumin (1 g/kg, once daily), administered orally plus an intraperitoneal injection of gemcitabine (25 mg/kg, twice weekly) was more effective than single agents at inducing the tumor growth inhibitory and anti-angiogenic effects in a pancreatic tumor model derived from MiaPaCa-2 pancreatic cancer cells orthotopically implanted in nude mice [27,154].…”

“…Moreover, curcumin potentiated the anti-proliferative and apoptotic effects induced by gemcitabine, a first-line chemotherapeutic drug, on BxPC-3, Panc-1 and MiaPaCa-2 pancreatic cancer cell lines in vitro [27,154]. A combination of curcumin (1 g/kg, once daily), administered orally plus an intraperitoneal injection of gemcitabine (25 mg/kg, twice weekly) was more effective than single agents at inducing the tumor growth inhibitory and anti-angiogenic effects in a pancreatic tumor model derived from MiaPaCa-2 pancreatic cancer cells orthotopically implanted in nude mice [27,154]. The chemosensibilizing effects of curcumin were mediated at least in part via the inhibition of STAT-3 and NF-kB-regulated gene products such as cyclin D1, c-Myc, Bcl-2, Bcl-xL, cellular IAP-1, COX-2, MMPs and VEGF in pancreatic cancer cells (Figures 1 and 2) [27,154].…”

Median Effect Dose and Combination Index Analysis of Cytotoxic Drugs Using Flow Cytometry

“…The formula for manual calculation is rather complicated and involves computing SE(log(D)) when D=Dm (shown in eq. 14, Table 5) but may be obtained using any software that implements this calculation such as Calcusyn or Compusyn (Bijnsdorp et al, 2011;Ikeda et al, 2011;Ramachandran et al, 2010). In practice the threshold value will be the minimal dose where the fraction of dead cells is higher than that of untreated cells.…”