The relationship between KRAS gene mutations and HLA class I antigen downregulation in the metastasis of non-small cell lung cancer.

Objective: To investigate the association between v-Ki-ras2 Kirsten rat sarcoma viral oncogene homologue (KRAS) gene mutations and levels of human leucocyte antigen (HLA) class I antigen in primary lung tumours and metastatic lymph nodes of patients with non-small cell lung cancer (NSCLC).

Methods: Patients with NSCLC undergoing tumour resection were enrolled. KRAS codon 12 mutations were analysed in normal lung and lymph node tissue, primary lung tumours and metastatic lymph nodes using polymerase chain reaction-restriction fragment length polymorphism analysis. HLA class I antigen immunostaining was examined using flow cytometry.

Results: A total of 65 patients participated in the study. All normal lung tissues had positive HLA class I antigen immunostaining. The majority of primary lung tumours (56/65) and all of the metastatic lymph nodes (31/31) had downregulated HLA class I antigen immunostaining. There was a positive correlation between downregulated HLA class I antigen in primary tumours and metastatic lymph nodes. There was a negative correlation between KRAS codon 12 mutations and the level of HLA class I antigen in primary and metastatic tumours.

Conclusions: KRAS codon 12 mutations appear to be important in the downregulation of HLA class I antigen in NSCLC. Abnormal activation of the oncogenic KRAS pathway might provide a new treatment target for NSCLC.