Objective: The recently identified PTEN/MMAC1/TEP1 gene is the first tumor suppressor encoding a phosphatase, which mutated in multiple tumors. Our research aims to detect loss of heterozygosity and inactivation of PTEN in lung cancer.
Methods: 24 lung cancer fresh samples paired with normal tissue, 18 archival paraffin-embedded sections of small cell lung cancer (SCLC) were included. For 24 fresh samples, PCR-LOH was used to detect Loss of heterozygosity (LOH) in or near PTEN loci. In situ hybridization, Western blot and or immunohistochemistry were proceeded for mRNA and protein expression of PTEN in lung cancer samples. Southern, Northern and Western blot were done to exam PTEN abnormality in one NSCLC and three SCLC cell lines.
Results: Among these 24 fresh samples PTEN LOH was detected in 11 out of 24 cases (45.8%) and 6 cases had no PTEN mRNA and protein expression. Results in situ hybridization were in conformity with that of immunohistochemistry/Western blot in our research. No protein expression was detected in 8/18 (44%) archival paraffin cases of SCLC. Southern, Northern and Western blot confirmed homozygous deletion in one SCLC cell line.
Conclusion: Lung cancers had LOH and inactivation of PTEN.