Sodium Orthovanadate Regulates The Sensitization Of Gastric Cancer Radiotherapy By Inhibiting Autophagy

Objective: The transition metal vanadium is found in the natural environment and has a variety of physiological and pharmacological effects on humans.Sodium orthovanadate(SOV),a well known vanadium compound,has shown significant antitumor activity in a variety of human cancers.In contrast,the effect of sodium orthovanadate on gastric cancer is unknown,and no study has reported the relationship between sodium orthovanadate and gastric cancer radiosensitivity.Therefore,in this study,we investigated whether sodium orthovanadate could sensitize gastric cancer cells to radiation radiotherapy.Methods: Human gastric adenocarcinoma cells SGC-7901,MGC-803 and SPF grade female BALB/c-nu/nu nude mice were used as the study subjects.(1)In this study,sodium orthovanadate was tested at different concentrations in gastric cancer cells SGC-7901 and MGC-803 using the Cell Counting Kit-8(CCK8)assay,and the IC50 value of sodium orthovanadate was measured.(2)Using a protein immunoblotting assay,autophagy levels were determined in SGC-7901 cells and MGC-803 cells under the effects of different drug concentrations.(3)The expression levels and autophagic activity of autophagy proteins LC3 B and P62 in five different experimental groups were detected by protein immunoblotting and cellular immunofluorescence,and the cell viability of three and five different experimental groups in the response experiment was detected by CCK8 assay.(4)Plate cloning and EDU assays were performed to detect whether sodium orthovanadate was radiosensitized in SGC-7901 cells and MGC-803 cells.(5)q RT-PCR was performed to determine the m RNA content of autophagy-related genes at different concentrations of sodium orthovanadate to screen out the target genes of drug action,and to determine the protein expression levels of target genes in control,radiation,radiation+sodium orthovanadate and radiation+sodium orthovanadate+ATG10co-treatment groups.(6)To construct a transplantation tumor model of SGC-7901 gastric cancer cells in nude mice,the effect of combined treatment with sodium orthovanadate and radiation on transplantation tumors was examined,and the protein expression levels of relevant autophagy genes in different groups of tumor tissues were detected by protein immunoblotting.Results:(1)The drug sodium orthovanadate showed significant inhibition of the viability of both gastric cancer cells.(2)The levels of autophagy in the cells decreased as sodium orthovanadate concentrations increased,indicating that sodium orthovanadate inhibits autophagy.(3)In the radioactive state,cell viability was inhibited,and the autophagy level of cells was elevated compared to the blank control group.Autophagy inhibitor 3-MA and autophagy enhancer rapamycin RAPA could regulate autophagy in the radiated state,with 3-MA inhibiting autophagy and suppressing cell viability in the radiated state and rapamycin RAPA enhancing autophagy and enhancing cell viability in the radiated state compared to the radiation-only group.Sodium orthovanadate has the same effect as 3-MA,inhibiting radiation-activated autophagy and suppressing cell viability.In the response assay,sodium orthovanadate modulated autophagy.(4)At the cellular level,sodium orthovanadate has a significant radiosensitizing effect.(5)With the elevation of sodium orthovanadate drug,the m RNA content of autophagy-related gene ATG10 was subsequently decreased.The protein ATG10 is present at higher levels when exposed to radiation.The amount of the protein ATG10 fell when radiation and sodium vanadate were present,and overexpressing ATG10 can halt the downward trend.(6)In in vivo experiments,sodium orthovanadate significantly decreased the growth rate of gastric cancer cells and increased their sensitivity to radiation.The expression of autophagy-related proteins in transplanted tumors showed that,consistent with in vitro studies,sodium orthovanadate acted on the gene ATG10,leading to a decrease in autophagic activity.Conclusion: Through its action on ATG10 and inhibition of radiation-induced autophagy,sodium orthovanadate can enhance radiosensitization of gastric cancer cells..Sodium orthovanadate is a promising strategy for radiosensitizing gastric cancer.