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  • Cisplatin receptor Demonstration of in vivo efficacy of pote

    2024-06-11

    Demonstration of in vivo efficacy of potential chemopreventive agents in animal models is necessary for their clinical development. Our present study provides experimental evidence that CuB 0.1μmol by oral administration (for 2weeks before the cancer cell injection, 5days per week) significantly inhibits the growth of PC-3 xenografts in athymic mice without causing weight loss or any other side effects. Similarly, CuB has been reported to inhibit the growth of several types of human cancer Cisplatin receptor in xenograft mouse models, including non-small-cell lung cancer H1299 cell [25], pancreatic cancer Panc-1 cell [21], [22], hepatocellular carcinoma BEL-7402 cell [24] and HepG2 [23], and breast cancer MDA-MB-231 cell [30]. These studies [21], [22], [23], [24], [25], [30] showed the chemotherapeutic effect of CuB in vivo. Our results are the first, however, to show the potential chemoprevention of CuB in prostate cancer. We also found that the CuB-mediated inhibition of PC-3 xenograft growth in vivo is associated with an increase in an immunoblotting band of cleaved PARP and cleaved Caspase 3 in tumors from CuB-treated mice as compared to those of the control mice (Fig. 3D). These observations are consistent with cellular studies in which treatment of PC-3 cells with CuB at 0.05–0.4μmol/L results in a concentration-dependent induction of apoptosis (Fig. 2). Thus, it is reasonable to conclude that the induction of apoptosis is a critical event in CuB-mediated growth inhibition of PC-3 cells in vivo. ACLY signaling is involved in the progress of many diseases including cancer [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. Inactivation of ACLY signaling has been implicated in the pathogenesis of many kinds of human cancers including prostate cancer [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. Our present results indeed suggest that ACLY signaling is also involved in CuB-induced prostate cancer cell growth inhibition and apoptosis induction. First, the phospho-ACLY levels were significantly reduced in PC-3 xenograft tumors in mice treated with CuB compared to those in the control mice (Fig. 3D). Next, down-regulation of the phospho-ACLY and ACLY proteins was observed in both prostate cancer PC-3 and LNCaP cells treated with CuB compared with the DMSO-treated control cells (Fig. 4A and B). In addition, CuB treatment caused a significant reduction of ACLY activity in both PC-3 (Fig. 6D) and LNCaP (data not shown) cells, as determined by a quantitative ACLY ELISA kit. These results suggest that CuB-induced prostate cancer growth inhibition was mediated by the downregulation of ACLY. Recently, it has been reported that the genetic or pharmacologic down-regulation of ACLY activity in cancer cells results in the inhibition of cell proliferation and induction of apoptosis in vitro and in vivo[7], [8], [9], [10], [11], [12], [13], [14], [15]. A more recent publication showed that ACLY inhibition may affect cancer stem cells in a broad range of genetic backgrounds and thus has widespread applicability [8]. Beckner et al. [16] reported that inhibition of ACLY with HT in a 12–24mmol/L treatment resulted in the suppression of in vitro glioblastoma cell migration, clonogenicity and brain invasion under glycolytic conditions. We therefore tested the effect of HT on cell growth and apoptosis in human prostate cancer cells. As shown in Fig. 4C–E, treatment with 20mmol/L HT significantly inhibited the proliferation and induced apoptosis, as well as downregulating the protein expression of ACLY. To determine the real role of ACLY in the CuB-induced apoptotic cell death in our models, we knocked down ACLY in the cells with ACLY-siRNA and then measured the ACLY protein expression and the induction of apoptosis. The present data showed that the inhibition of ACLY resulted in a reduction of cell viability and an increase of apoptosis in human prostate cancer cells. The CuB-induced downregulation of ACLY and induction of apoptosis were significantly enhanced by the siRNA knockdown in both cancer cell lines (Fig. 5A–C). To further support the regulatory role of ACLY in CuB-induced apoptosis, we overexpressed ACLY via pCMV-ACLY in the cancer cell lines. Interestingly, the overexpression of ACLY significantly protected against the induction of apoptosis induction by CuB in these cells (Fig. 5D–F). Taken together, these results indicated that ACLY is the real target for the CuB-induced apoptosis in human prostate cancer cells.