Expression Of HER2 And P300 Gene In Non-small Cell Lung Cancer And Their Mutation Analysis

Objective:To detect the expression of HER2 and P300 gene in non-small cell lung cancer (NSCLC) at protein and mRNA levels,analyze the relationship between their expression and the clinic- pathological parameters;to explore the mutations of P300 and HER2 gene in non-small cell lung cancer,form a fundament for studying the carcinogenic mechanism of lung cancer and Molecule Targeted Therapy.Methods:(1) to investigate the HER2 and P300 mRNA expression by RT-PCR,analyze the relationship between their mRNA expression and clinic parameters.(2) to detect the expression of HER2 and P300 protein in 71 NSCLCs by immunochemistry,analyze the relationship between their expression and clinic parameters;(3) amplificate the exons of HER and P300 gene which showed frequently mutation in cancer by PCR,and screen the samples which mutate in the two genes by SSCP-silver staining,then sequence that sample to confirm the mutation.Results:1) HER2 mRNA in 36 specimens were positively expressed and 15 ones were overexpressed in the 50 NSCLCs tumor samples while in the matched normal tissues 26 cases were positive and none was overexpression.HER2 mRNA overexpression was correlated with lymph transfering and clinic TNM staging.the overexpression of HER2 mRNA in TNMâ…¢+â…£group(54.5%) is significantly higher than that in TNMâ… +â…¡group(10.7%,P=0.035).the overexpression rate of lymph transfered group(40.6%) remarkably higher than the group,which has not been transferred as well(11.1%,P=0.029).P300 mRNA was positively expressed in 39 specimens and overexpressed in 21 samples of 50 tumor tissues while in normal matched tissues 30 cases were positive and no overexpression was detected.Its overexpression was not correlated with all the pathological parameters.HER2 mRNA overexpression was not correlated with P300 mRNA overexpression analyzed by Spearman Relation Test;2) Although the overexpression of HER2 and P300 in normal lung tissue was not found,the protein expression of HER2 and P300 in NSCLCs was detected with which high expression of HER2 was detected as 34%(24/71)and 54.9%for P300(39/71).The rate of protein expression in lung adeno-carcinomas was 45.5%(20/44) while expression rate was 19.9%(4/21) in the squamous carcinomas.These differences have statistics meanings(P=0.039).the overexpression rate of lymph transfered group(43.2%,19/44) remarkably higher than the group,which has not been transferred(18.5%,5/27)as well(P=0.033).HER2 overexpression correlated with TNM staging, the overexpression of HER2 in TNMâ…¢+â…£group(53.3%,16/30) is significantly higher than that in TNMâ… +â…¡group(19.5%,8/41)(P=0.003).P300 protein overexpression was not correlated with all the parameters.Compaired with the protein and mRNA expression,in 90% (45/50) specimens HER2 protein expression concorded with mRNA expression while the concordance rate of P300 protein and mRNA was 86%(43/50);3) All the four fragments targeting HER2 and P300 gene were successfully amplificated in all 50 samples by PCR,and 2 mutation -suspected samples were found by SSCP-silver staining.the two mutations were in-frame insertion,2327₂329 ins TCT(G776 del VC ins),in exon 20 of HER2 gene confirmed by direct sequencing.mutation was not detected in two exons of P300 gene in 50 NSCLCs.Conclusion:1.Overexpression of HER2 and P300 mRNA and protein was found in NSCLCs.HER2 gene overexpression was correlated with clinic staging,and lymph transfering,and it can behave as a bad molecular marker in NSCLCs.P300 gene overexpression was not correlated with all the pathological parameters.There were no relationship between p300 and her2 mRNA or protein overexpression.2.Our data demonstrated that in NSCLCs,HER2 and P300 protein and mRNA are simultaneously expressed with a high degree of correlation and their protein expression is closely associated with their gene transcription.3.The HER2 mutations were found in NSCLCs and can be a targeting point for Molecule Targeted Therapy.4.No mutation of p300 gene was found in 50 NSCLCs,showing its mutation in NSCLCs was rare.PCR-SSCP is an effective method for screening the mutation of DNA.