| BackgroundPancreatic cancer is considered one of the most deadly forms of cancer. Only1%to4%of all patients with adenocarcinoma of the pancreas will survive5years posttreatment. In order to improve the outcome of treatment for pancreatic cancer, effective adjuvant chemotherapy is necessary in the treatment of pancreatic cancer. Gemcitabine (GEM) is widely used in the chemotherapy of pancreatic cancer and is considered to be one of the most important agents against pancreatic cancer. A substantial number of patients with pancreatic cancer, however, are resistant to the currently used adjuvant GEM-based chemotherapy, and the benefit of chemotherapy is limited to a number of patients. The DNA repair protein, O6-methylguanine-DNA methyltransferase (MGMT), is highly expressed in pancreatic cancers, and confers tumor resistance to a variety of anticancer alkylating agents. Several researches showed that MGMT inhibitor could increase the chemosensitivity as an adjuvant.The chemotherapy sensitivity test for carcinoma used in the past was based on monolayer cultured cells in a two-dimensional model, while the pancreatic cancer cells in the human body survive in a three-dimensional growing model. Monolayer cultured cells model neglects the different characteristics between a whole tumor and its individual tumor cell as well as the interactions between tumor cells and the impacts of the microenvironment. Monolayer cultured cell model can not imitate the environment in vivo, nor can it provide a reliable platform for pancreatic cancer chemotherapy sensitivity test in vitro studies. More and more researches in recent years showed that the interaction between tumor cells and the microenvironment is the basis for tumor growth and survival, which may be involved in the regulation of drug reactions and the incidence of cancer drug resistance. In previous research, we have established a3-D culture model in the type I collagen.ObjectiveRelationship between MGMT expression and chemosensitivity of pancreatic carcinoma cell lines in2-dimensional culture model and MCS model was investigated. The prepose of our study was to evaluate the prospect of MGMT as a new marker for individualized chemotherapy of pancreatic cancer.MethodsQuantification of the mRNA levels was carried out using a real-time fluorescence detection method. Western Blotting analysis was performed to detect MGMT protein expression in seven cell lines. Chemosensitivity test of cells were added into96-well multi-plates with CCK-8. Data are presented as the Means±SD. Statistical significance was determined using one-way ANOVA, independent-sample t-test and Student-Newman-Keuls analysis. All statistical tests were two-sided and differences were considered significan at p<0.05.ResultsReal-time fluorescence PCR and Western Blotting show that:The expressions of MGMT in different PANCreatic cancer cells are significantly different(p<0.05). The expression of MGMT in PANC-1cell line is higher than other cell lines. There is no significantly different between2-D and MCS model in SW1990and ASPC-1cell lines. Chemosensitivity:Cell lines with high expression of MGMT are more resistant to GEM than the cell lines with low expression of MGMT (p<0.05). MCS model of SW1990and ASPC-1cell lines are more resistant to GEM than the2-D model (p<0.05).Conclusions1. The expression level of MGMT in pancreatic cancer cell lines is different to each other. We can divide the cell lines into two groups, one is the cells with low MGMT protein expression, the other one with high MGMT protein expression.2. SW1990cells had lower MGMT protein expression than SW1990/GEM cells.3. The cells with low MGMT protein expression were shown to exhibit significantly higer GEM sensitivity in vitro than the cells with high MGMT protein expression.4. In MCS model based on collagen I:1) There was no significant different in MGMT protein expression level between2-D and3-D models in the same cell line.2) MCS cells are more resistant to GEM than the2-D cell codels. |
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