AIMTo investigate the response to hyperthermia and chemotherapy, analyzing apoptosis, cytotoxicity, and cisplatin concentration in different digestive system cancer cells.METHODSAGS (gastric cancer cell line), Caco-2 (colon cancer cell line) and T3M4 (pancreatic cancer cell line) were treated by cisplatin and different temperature setting (37 °C to 45 °C) either in isolation, or in combination. Treatment lasted for one hour. 48 h after the treatment viability was evaluated by MTT, cell apoptosis by Annexin V-PE and 7ADD flow cytometry. Intracellular cisplatin concentration was measured immediately after the treatment, using mass spectrometry. Isobologram analysis was performed to evaluate the mathematical combined effect of temperature and cisplatin.RESULTSAGS cells were the most sensitive to isolated application of hyperthermia. Hyperthermia, in addition to cisplatin treatment, did not provoke a synergistic effect at intervals from 37 °C to 41 °C in neither cancer cell line. However, a temperature of 43 °C enhanced cisplatin cytotoxicity for Caco-2 cells. Moreover, isobologram analysis revealed mathematical antagonistic effects of cisplatin and temperature combined treatment in AGS cells; variations between synergistic, additive, and antagonistic effects in Caco-2 cells; and additive and antagonistic effects in T3M4 cells. Combined treatment enhanced initiation of cell apoptosis in AGS, Caco-2, and T3M4 cells by 61%, 20%, and 19% respectively. The increase of intracellular cisplatin concentration was observed at 43 °C by 30%, 20%, and 18% in AGS, Caco-2, and T3M4 cells, respectively.CONCLUSIONIn addition to cisplatin, hyperthermia up to 43 °C does not affect the viability of cancer cells in a synergistic manner.
AIMTo determine the association of human antigen R (HuR) and inhibitors of apoptosis proteins (IAP1, IAP2) and prognosis in pancreatic cancer.METHODSProtein and mRNA expression levels of IAP1, IAP2 and HuR in pancreatic ductal adenocarcinoma (PDAC) were compared with normal pancreatic tissue. The correlations among IAP1/IAP2 and HuR as well as their respective correlations with clinicopathological parameters were analyzed. The Kaplan-Meier method and log-rank tests were used for survival analysis. Immunoprecipitation assay was performed to demonstrate HuR binding to IAP1, IAP2 mRNA. PANC1 cells were transfected with either anti-HuR siRNA or control siRNA for 72 h and quantitative reverse transcription polymerase chain reaction (RT-PCR), western blot analysis was carried out.RESULTSRT-PCR analysis revealed that HuR, IAP1, IAP2 mRNA expression were accordingly 3.3-fold, 5.5-fold and 8.4 higher in the PDAC when compared to normal pancreas (P < 0.05). Expression of IAP1 was positively strongly correlated with HuR expression (P < 0.05, r = 0.783). Western blot analysis confirmed RT-PCR results. High IAP1 expression, tumor resection status, T stage, lymph-node metastases, tumor differentiation grade, perineural and lymphatic invasion were identified as significant factors for shorter survival in PDAC patients (P < 0.05). Immunohistological analysis showed that HuR was mainly expressed in the ductal cancer cell’s nucleus and less so in cytoplasm. RNA immunoprecipitation analysis confirmed IAP1 and IAP2 post-transcriptional regulation by HuR protein. Following siHuR transfection, IAP1 mRNA and protein levels were decreased, however IAP2 expression levels were increased.CONCLUSIONHuR mediated overexpression of IAP1 significantly correlates with poor outcomes and early progression of pancreatic cancer. Further studies are needed to assess the underlying mechanisms.
Gastrointestinal cancers (gastric, pancreatic and colorectal) are life-threatening diseases, which easily spread to peritoneal cavity (Juhl et al. in Int J Cancer 57:330-335, 1994; Schneider et al. in Gastroenterology 128:1606-1625, 2005; Geer and Brennan in Am J Surg 165:68-72 1993). Application of hyperthermal intraperitoneal chemotherapy (HIPEC) is one of the choices treating these malignancies and prolonging patient survival time. Despite numbers of clinical trials showing positive effects of HIPEC against various types of cancer, the question whether hyperthermia significantly potentiate the cytotoxicity of cisplatin remains unanswered. Little information is available on the HIPEC effect at the level of mitochondria. To define the effect of hyperthermia (40 °C and 43 °C) to cisplatin treated human gastric AGS, pancreatic T3M4 and colorectal Caco-2 cancer cells, we established an in vitro experiment, which mimics clinical HIPEC conditions. Giving the importance of mitochondrial energy metabolism in cancer, we investigated the effect of cisplatin and hyperthermia on mitochondrial Complex-I (glutamate/malate) and complex-II (succinate) dependent respiratory rates, the coupling of oxidative phosphorylation, the proton permeability of mitochondrial inner membrane and on the integrity of mitochondrial outer membrane in Caco-2, AGS and T3M4 cancer cell lines. Our main findings are: 1) treatment of cells with cisplatin causes the impairment of mitochondrial functions - the increase in the proton permeability of mitochondrial inner membrane and decrease in the oxidative phosphorylation efficiency in Caco-2, AGS and T3M4 cancer cells; 2) hyperthermia (40 °C and 43 °C) increased state 2 respiration rate only in AGS cells without any effects on Caco-2 and T3M4 cells; 3) hyperthermia in combination with cisplatin doesn't enhance cisplatin effect neither in Caco-2 and T3M4 nor in AGS cells. Thus, our results show the different mitochondrial response of gastric AGS, pancreatic T3M4 and colorectal Caco-2 cancer cells to cisplatin or/and hyperthermia - treatment. Further studies are needed to find the mechanisms of cell line - specific mitochondrial response to cisplatin and hyperthermia.
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