Frequency of oncogenic alterations in five driver genes in Chinese female lung adenocarcinoma.

Abstract

1588 Background: Currently, 5 driver genes (EGFR, K-RAS, B-RAF, ALK, RET) have been widely explored and become new targets of NSCLC, however no report has been found in Chinese female lung adenocarcinoma, who were prone to EGFR mutations and therefore, are the targets for TKIs therapy. Methods: FFPE-tissues from 310 female lung adenocarcinoma adopted in Hunan or Henan province between 2000 and 2012 were investigated. Oncogenic alterations in newly found 5 driver genes were analyzed. ARMS was used to study EGFR, K-RAS and B-RAF mutation. The reverse transcription and real-time PCR were performed to detect either ALK and RET fusions or ALK and RET gene expression. Sequencing was further applied to confirm the subtypes of fusions. Results: Among 310 samples, 149 (48.1%) EGFR mutations, 16 (5.2%) KRAS mutations, 0 (0%) BRAF mutations, 23 (7.4%) ALK fusions and 5 (1.6%) RET fusions were detected. Only EML4-ALK fusion but no other ALK fusions were found. Further research showed that cases (22, 95.6%) with high ALK expression were often accompanied by EML4-ALK fusion and poorly differentiated adenocarcinoma. Two RET fusions, KIF5B-RET and CCDC6-RET were found, with 2 cases and 3 cases, respectively. The ratio of RET/ABL mRNA levels was significantly higher in CCDC6-RET samples with poorly differentiated adenocarcinoma. However, with KIF5B-RET fusion, relatively high RET/ABL mRNA expression was detected in one KIF5B-RET sample with moderately differentiated adenocarcinoma, while no RET expression was detected in other two KIF5B-RET samples with highly differentiated adenocarcinoma. Conclusions: This is the first research about the oncogenic alterations of 5 important driver genes in Chinese female lung adenocarcinoma, as well as the correlation between ALK fusion and ALK expression or between RET fusion and RET expression, thus laying good foundation for understanding the genetic mutation spectrum in female lung adenocarcinoma.