LKB1 mutation in large cell carcinoma of the lung

• Published in: Lung cancer (Amsterdam, Netherlands) Vol. 53; no. 3; pp. 285 - 294
• Main Authors: Zhong, Diansheng, Guo, Lizheng, de Aguirre, Itziar, Liu, Xiuju, Lamb, Neil, Sun, Shi-Yong, Gal, Anthony A., Vertino, Paula M., Zhou, Wei
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.09.2006; Elsevier Science
• Subjects: Adenocarcinomas; Alleles; AMP-Activated Protein Kinases; AMPK signaling; Biological and medical sciences; Carcinoma, Large Cell - metabolism; Cell Line, Tumor; DNA, Complementary - metabolism; Gene Deletion; Gene Expression Regulation, Neoplastic; Green Fluorescent Proteins - metabolism; Homozygote; Humans; Large cell carcinomas; LKB1; Loss of Heterozygosity; Lung Neoplasms - genetics; Medical sciences; Multienzyme Complexes - metabolism; Mutation; Non-small cell lung carcinoma (NSCLC); Phosphorylation; Pneumology; Protein Structure, Tertiary; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Protein-Serine-Threonine Kinases - physiology; Tumor suppressor gene; Tumors of the respiratory system and mediastinum; AMPK signaling; Large cell carcinomas; Mutation; Adenocarcinomas; LKB1; Tumor suppressor gene; Non-small cell lung carcinoma (NSCLC); Adenocarcinoma; Lung disease; Respiratory disease; Lung cancer; Malignant tumor; non-small cell lung carcinoma; cAMP-dependent protein kinase; Bronchus disease; Large cell carcinoma; Non small cell carcinoma
• ISSN: 0169-5002; 1872-8332
• DOI: 10.1016/j.lungcan.2006.05.018

Germline inactivation of LKB1 is responsible for Peutz–Jeghers syndrome, an autosomal dominant disorder characterized by benign hamartomas of the GI tract and an increased predisposition to certain cancers, including lung. Acquired mutations in LKB1 are rarely observed in most sporadic tumor types except for adenocarcinomas of the lung where up to 50% harbor inactivating mutations. In this study, we focused on LKB1 mutations in lung cancer cell lines originating from large cell carcinomas. We identified a novel 1.5 kb interstitial deletion within LKB1 gene in H157 cancer cells. Homozygosity mapping-of-deletion analysis (HOMOD) analysis showed that the deletion is accompanied by LOH of one parental allele, indicating biallelic inactivation of LKB1. This deletion results in an LKB1 transcript lacking exons 2 and 3 and a predicted in-frame deletion of 58 amino acids within the kinase domain of the LKB1 protein. The truncated transcript was expressed at relatively low levels, and the truncated LKB1 protein was virtually undetectable in this cell line. To determine the impact of LKB1 protein truncation on its function, we examined AMPK-α, a downstream target of LKB1 kinase activity triggered by low energy stress conditions. Phosphorylation of AMPK-α was attenuated in H157 cells treated with 2-deoxyglucose, and could be rescued by expression of an exogenous GFP-LKB1 fusion protein. Therefore, our data suggest that LKB1 function is compromised in H157. Of the four cell lines and six primary tumors of large cell lung carcinoma origin that have been evaluated in this and other studies, LKB1 mutations have been found in three cases. These results suggest that, in addition to adenocarcinomas, acquired loss of function mutations in LKB1 may also be frequently involved in the pathogenesis of large cell lung carcinomas.