Abstract
Background: Circulating DNA and RNA is an important prognostic tool for noninvasive malignant disease detection and in disease prognosis. Study aimed to evaluate the possible prognostic role of HER2 (-3444C/T) promoter polymorphism and its mRNA expression in Lung adenocarcinoma patients using circulating DNA and RNA.
Methods: One hundred newly diagnosed lung adenocarcinoma patients and 100 age and sex matched healthy controls were included and allele specific (AS) polymerase chain reaction (PCR) was used for genotyping and expression was analyzed by quantitative real time PCR. Overall survival of patients was analyzed by Kaplan-Meier method.
Results: We observed a statistically significant difference in the frequency of HER2 CC, CT, and CT genotype among lung adenocarcinoma cases vs. healthy controls (P=0.001). Compared to the CC genotype, OR 2.51 (1.4-4.51), 5.97 (1.17-30.41) and RR 1.56 (1.17-2.07), 2.83 (0.82-9.73) for heterozygous CT and homozygous TT genotypes suggesting possible dominant effect on risk of lung adenocarcinoma. Cases with CC genotype showed 9.29 fold increased mRNA expression while cases with heterozygous CT and homozygous TT genotype showed 16.26, 16.72 fold increased mRNA expression (P<0.0001). We observed 13.92 fold increased HER2mRNA expression Lung adenocarcinoma patients. Patients in different TNM stages showed significant difference in HER2 mRNA expression which was found to be significantly associated (P<0.0001). Patients with distant metastases and without distant metastases had 17.44 and 11.16 fold increased HER2 mRNA expression was also found to be significantly associated (P<0.0001). It was also observed that patients with pleural effusion and without pleural effusion showed significant difference in HER2 mRNA expression (P=0.03). We also analysed patients with CC, TT, CT (P=0.02) and CT + TT (P=0.008) genotype showed 15.8, 7.9, 9.5 and 7.9 months of overall median survival time and found to be significantly associated, respectively. Patients with >13 and <= 13 fold increased HER mRNA expression also showed 7.9 and 11.5 months of overall median survival time was also found to be significantly associated (P=0.01).
Conclusions: Our work provides evidence that circulating DNA and RNA may be a potential prognostic tool in Lung adenocarcinoma patients. Promoter polymorphism of HER2 (-3444C/T) gene had significant impact on higher HER2 mRNA expression could be a predictive factor for patients' worse overall survival and metastatic behaviour.