Expression Of Class Ⅲβ-tubulin, MAPT, Survivin And Exvivo Chemosensitivity Testing On Predicting Response Towards Paclitaxel Treatment In Gastric Cancer

Background and Objective: Gastric cancer is one of the most common malignancies over the world. With the great incidence and mortality, it makes a serious menace to human health. Notwithstanding the constantly emerging of new anticancer drugs in recent years, chemotherapy, which has been an important therapy when treating advanced or metastatic gastric cancer, does not manage to make expected curative effect in most cases. One of the key contribution to this failure lay on the fact that the gastric cancer cell has developed a resistance to chemotherapy drugs. As member of important anticancer drugs, paclitaxel is widely used and achieved some good results in treating gastric cancer and other malignant tumors etc. However, subject to the clinical observation, this kind of curative results and adverse effects of paclitaxel varied between individual patients. Given this consideration, it does make sense for individual treatment plan for gastric cancer sufferer to find biological predicting factors related to the sensitivity of paclitaxel chemotherapy. Drug sensitivity evaluated by ATP-tumor chemosensitivity assay (ATP-TCA), one of in vitro drug sensitivity tests, was observed to predict response against chemotherapy in many cancer types, such as lung cancer, colorectal cancer, ovarian cancer. According to recent research, it is the Abnormal Expression of Tubulin Isomers, Microtubule-associated protein Expression and Apoptosis Suppression caused by the high expression of IAPs that may be related to tumor cells'developing of resistance to paclitaxel. Under this set of experiments, we explored the association between the sensitivity to paclitaxel and the levels of class IIIβ-tubulin, microtubule-associated protein tau and survivin in order to identify the biological predictors to chemosensitivity of gastric cancer.Methods: 1. Fifty-four cases of fresh gastric cancer samples were collected. Isolated suspending tumor cells were obtained after seperation, digestion, purification and suspension. Cells were subsequently incubated in fluorouracil for 5~7 days. ATP-TCA was used to test the in vitro chemosensitivity of primarily cultured gastric cancer cells. 2. By using the chemical of Trizol, we extracted total RNA out of the samples and tested mRNA expression of Class IIIβ-tubulin, MAPT and survivin respectively with the method of RT-PCR. 3. Picking up the total protein out of the samples, we tested protein expression of Class IIIβ-tubulin, MAPT and survivin respectively with the method of Western Blot. 4. Data was analysised to explore the assosiation between the mRNA and protein expression levels of the three biological indicators and in vitro chemosensitivity to paclitaxel.Results: Out of the total 54 samples, 6 were highly sensitive, 13 were partly sensitive, 10 were weakly sensitive while the other 25 were resistant. Overall effectiveness of paclitaxel was 53.70% (29/54). The mRNA expression levels of class IIIβ-tubulin, MAPT and survivin were 1.04±0.22, 0.80±0.17, 1.00±0.19 respectively. The mRNA expressions of Class IIIβ-tubulin and survivin were statistically correlated to the grade of tumor cells differentiation respectively (P = 0.029, 0.009). Index of Chemosensitivity was inversely correlated to the mRNA and protein expression of Class IIIβ-tubulin (Statistically, r = -0.372, -0.350; P = 0.006, 0.009); inversely correlated to the mRNA and protein expression of MAPT (Statistically, r = -0.292, -0.289; P = 0.032, 0.034); inversely correlated to the mRNA and protein expression of survivin (Statistically, r = -0.340, -0.296; P = 0.012, 0.030). mRNA and protein expression of Class IIIβ-tubulin and that of MAPT were positively correlated (Statistically, r = 0.284, 0.440; P = 0.037, 0.001).Conclusion: 1. Expression of Class IIIβ-tubulin, MAPT and survivin might be of great value in predicting sensitivity of gastric cancer against paclitaxel. 2. mRNA expression of Class IIIβ-tubulin and survivin were all remarkably correlated to histological grade of the tumor. No significant correlation was observed between the mRNA expression and the age or gender of the patients, location of the tumor, lymph nodes metastasis. 3. mRNA and protein expression of Class IIIβ-tubulin and MAPT were positively correlated, indicating that there might be some level during the common adjusting mechanism to produce resistance. 4. Given the good maneuverability and objectivity, ATP-TCA made a good choice for testing chemosensitiviy (in vitro) to drugs.