Relationship Between Pokemon And Multidrug Resistance In Gastric Carcinoma Tissue And Lymph Node Metastases

Objective:Gastric carcinoma is one of the most common digistive malignant tumors.Owing to the difficulty of discovering clinical symptoms and signs during early stage,most cases of gastric carcinoma are in advanced stage when diagnosed,with local or distant metastasis,which leading to poor prognosis.Although chemotherapy is effective on gastric carcinoma,the phenomenon of multi-drug resistance(MDR)leads to failure of chemotherapy and high mortality of the disease.MDR is defined as the resistance of tumor cells to one chemotherapeutic agent accompanied by other different structural and mechanistic chemotherapeutic agents.MDR contains intrinsic MDR and acquired MDR,the former means insensitivity of tumor cells to chemotherapeutic agent in the beginning,the latter means the sensitivity of tumor cells to chemotherapeutic agent changes from sensitive to insensitive after several courses of treatment.The mechanism of MDR is complicated and is influenced by different genes and pathways.Pokemon,POK erythroid myeloid ontogenic factor,is one of the members of POK family of transcription repressors.The family plays an important role in embryo growth,differentiation and carcinogenesis.It's confirmed that Pokemon can not only regulate cell growth,but also activity of some oncogenes and tumor suppressor genes via different mechanisms.Though studies indicate that Pokemon is involved in tumorigenesis and metastasis,whether it participates in MDR or not is unclear.In this research,quantitative real-time PCR and S-P immunohistochemical methods were performed to evaluate mRNA and protein expression of Pokemon and MDR related factors in gastric carcinoma and metastatic lymph nodes tissues,accompanied by MTT susceptibility test,to analyze the correlation between Pokemon and MDR related factors,and the correlation between Pokemon and drug sensitivity,thus provide basic theoryfor clinical treatment.Methods:The specimens of cases with advanced gastric carcinoma were collected,including 40 cases of gastric carcinoma tissue and the corresponding metastatic lymph nodes.Quantitative real-time PCR was used to detect Pokemon expression in gastric carcinoma and metastatic lymph nodes,S-P immunohistochemical method was performed for expressions of P-gp,MRP-1,GST-? and TS in the two different kinds of tissues.Using MTT chemosensitivity test,we detected the sensitivity of two kinds of gastric cancer cells on four kinds chemotherapy drug,5-Fu,VCR,PTX,OXA.At last,we analyze the correlations between Pokemon and MDR related factors,and the correlation between Pokemon and drug sensitivity.All of statistical analyses were carried out with SPSS 19.0,significance was assessed in all experiments as a value of P<0.05.Results:1 The mRNA and protein expression of Pokemon in gastric carcinoma and metastatic lymph nodes.The qPCR results showed there was no significant difference in the relative expression of Pokemon mRNA in gastric carcinoma and metastatic lymphnodes(0.196±0.375vs0.098±0.071;Z=-0.282,P=0.778).Immunohistochemical method indicated the difference of Pokemon expression between gastric carcinoma and metastatic lymph nodes was insignificant(65%vs70%,P>0.05).And the negative correlativity of Pokemon expression was found between gastric carcinoma and metastatic lymph nodes(r=-0.128,P>0.05).2 The protein expression of P-gp,MRP-1,GST-?,TS in gastric carcinoma and metastatic lymph nodes.The protein expressions of P-gp,MRP-1,TS were all significantly higher in metastatic lymph nodes groups than gastric carcinoma groups(all P<0.05).There was no statistical difference of GST-? between gastric carcinoma and metastatic lymph nodes(P>0.05).There were positive correlations of P-gp and MRP-1 expressions between gastric carcinoma and metastatic lymph nodes(r=0.332,r=0.427,all P<0.05).3 The correlations between Pokemon and MDR factors in gastric carcinoma and metastatic lymph nodes.There were positive correlations between Pokemon and p-gp both in gastric carcinoma and metastatic lymph nodes(r=0.399,r=0.325,all P<0.05).There were positive correlations between Pokemon and MRP-1 both in gastric carcinoma and metastatic lymph nodes(r=0.428,r=0.326,all P<0.05).There was a positive correlation between Pokemon and TS in gastric carcinoma(r=0.508,P<0.05).4 The relationships between expressions of chemotherapeutic agents and chemosensitivities in gastric carcinoma and metastatic lymph nodes cells.The inhibition rates of gastric carcinoma cells for VCR and OXA were lower than metastatic lymph nodes cells,respectively(all P<0.05).The inhibition rates of gastric carcinoma cells for 5-Fu and PTX were not different from those of metastatic lymph nodes cells(all P>0.05).5 The correlations between Pokemon and chemosensitivities in gastric carcinoma and metastatic lymph nodes cells.In gastric carcinoma cells,the inhibition rates to VCR and PTX were significantly lower in Pokemon high expression group than low group(all P<0.05).As for metastatic lymph nodes cells,the inhibition rates to 5-Fu,VCR and OXA were significantly lower in Pokemon high expression group than low group(all P<0.05).Conclusion:1 The positive expression rates of Pokemon in both gastric carcinoma and metastatic lymph nodes are high,which indicated that Pokemon may be related to carcinogenesis and lymph node metastasis,and as a gene therapy target.The Pokemon expression is uncorrelated between gastric carcinoma and metastatic lymph nodes,revealed that Pokemon may play different roles in gastric carcinoma and metastatic lymph nodes.2 We can conclude that P-gp,MRP-1,GST-?,TS related to gastric cancer's intrinsic MDR,from the high expression rates of those proteins are high in both gastric carcinoma and metastatic lymph nodes.As a result of theexpressions of P-gp,MRP-1,TS are significantly higher in metastatic lymph nodes than gastric carcinoma,we can also have a conclusion that there is a difference of drug resistance between gastric carcinoma and metastatic lymph nodes,the latter may have a stronger drug resistance.3 There are positive correlations between Pokemon and P-gp,MRP-1,respectively,in both gastric carcinoma and metastatic lymph nodes,indicates that Pokemon participates in intrinsic MDR via certain mechanism regulating P-gp and MRP-1.The correlation between Pokemon and TS in gastric carcinoma is different from that in metastatic lymph nodes,shows that Pokemon may have a heterogeneous change in regulating TS.4 The expression of Pokemon participates in only part of the chemosensitivity of drugs,indicates MDR of gastric carcinoma is a result of multi-mechanisms.