| Objective:Gastric cancer is the most common malignant tumor of digestive tract in China,and the mortality rate ranks the third among all the malignant tumors.Although its incidence has been reduced in recent years,the mortality rate is still high,which is the most common malignant tumor seriously endangering people’s health Chemotherapy is the main choice for patients with gastric cancer.Irinotecan is a first-line chemotherapy drug for advanced gastric cancer,but there are still many patients who fail because of drug resistance.In recent years,more and more studies have pointed out that pH value of microenvironment plays an important role in tumor occurrence,development and drug resistance.The two most important markers of tumor microenvironment are anoxic and acidic(low pH value).The microenvironment characteristics of tumor selection affect the efficacy of some weakly basic chemotherapy drugs.The purpose of this study was to investigate the effects of irinotecan on the biological characteristics(proliferation,apoptosis and invasion)of BGC823 cells under different pH conditions and its primary mechanisms.Methods:BGC823 cell line of gastric cancer was cultured in vitro.The effect of irinotecan on the proliferation of BGC823 cell line was detected by CCK-8 method under different pH conditions.The morphology of apoptotic cell was observed under fluorescence microscope.The apoptotic rate of gastric cancer cell line was detected by annexin V-PI double staining.qRT-PCR was used to detect the expression of NF-κ B,Bcl-2 and Bax in gastric cancer cells.Results:(1)Under the normal pH value(pH=7.2),the proliferation of BGC823 cells was positively correlated with the concentration of irinotecan.The IC50 value of irinotecan was 73.81 ug/ml.(2)After 48 hours of cell culture,the OD450 value of cells was 2.65±0.16 at pH 6.8,at pH 7.2,7.4 and 7.6,the OD450 values were 1.96±0.12,1.44±0.13 and 1.67±0.09,respectively,there was significant difference between the pH7.2,7.4.7.6 and pH 6.8(P<0.05);after 72 hours of cell culture,the OD450 value of cells was 3.44±0.07 at pH 6.8,at pH 7.2,7.4 and 7.6,the OD450 values were 2.69±0.07,1.75±0.23 and 1.5 8±0.20,respectively,there was significant difference between the pH7.2,7.4,7.6 and pH 6.8(P<0.05).There was no significant difference between pH7.4 group and ph7.6 group(P>0.05).(3)After 48 hours of cell culture,gastric cancer cells in pH 6.8 and 7.2 groups showed logarithmic growth,good cell status and regular morphology.In the weak alkaline condition(pH 7.4.7.6 group),the number of cells decreased significantly,and the morphology was irregular.With the increase of pH concentration,the number of apoptotic cells in gastric cancer BGC823 cells treated with irinotecan increased significantly(4)At pH 7.4 and 7.6,the apoptosis rate was(18.1±0.65)%and(18.8 ± 0.49)%respectively.At pH 6.8,the apoptosis rate was(8.5±0.98)%.There was significant difference between the two groups(P<0.05).There was no significant difference between ph6.8 group and ph7.2 group(P>0.05).(5)With the increase of pH,the expression levels of Bcl-2 and NF-κB decreased significantly(P<0.01)and Bax increased significantly(P<0.05)after CPT-11 treatment.Conclusion:To a certain extent,increasing the pH value of tumor extracellular environment can significantly improve the inhibitory effect of CPT-11 on the proliferation of gastric cancer BGC823 cells,and promote the apoptosis of tumor cells,That is to say,the extracellular alkaline environment of gastric cancer can improve the ability of CPT-11 to promote the apoptosis of tumor cells,inhibit the proliferation and invasion of tumor cells,which is related to the pH value of gastric cancer microenvironment The improvement of the effect may be achieved by inhibiting the anti apoptotic genes such as NF-κB and Bcl-2 and increasing the expression of Bax Pro apoptotic genes. |
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