The invention related to the use of high-density loss of heterozygosity (LOH) mapping in lung adenocarcinoma to identify intragenic LOH and driver mutations in different domains of ALK resulted in enhanced tumor growth in xenografted mouse. Mutant (H694R and E1384K) ALKs showed activation of Y1604 ALK and downstream AKT, STAT3 and ERK signaling pathways. Increases of oncogenic signalings resulted in enhanced cell proliferation, colony-formation, cell-migration and tumor-growth in xenografted mouse. Western blot and immunohistochemistry analysis using antibody against phospho-Y1604 ALK on 11 lung cancer cell-lines and 263 cancer specimens indicated ALK activation in all lung cancers regardless of tumor stages. Treating mutant-bearing mice with ALK inhibitor WHI-P 154 resulted in tumor shrinkage, metastasis suppression, and improved survival. Hyperphosphorylation of Y1604 ALK occurred early and continuously throughout tumor progression and could be used as a biomarker to detect lung cancer. Oncogenic ALK point mutations could be treatment targets for lung cancer.
