Frequent loss of the expression of multiple subunits of the SWI / SNF complex in large cell carcinoma and pleomorphic carcinoma of the lung

The switch/sucrose non‐fermenting ( SWI / SNF ) complex has recently emerged as a novel tumor suppressor in various human cancers. In the present study, we analyzed the expression of multiple SWI / SNF subunits in primary non‐small cell lung cancer ( NSCLC ). A total of 133 NSCLC , consisting of 25 squamous cell carcinomas ( SCC ), 70 adenocarcinomas ( AD ), 16 large cell carcinomas ( LC ), and 22 pleomorphic carcinomas ( PL ), were immunohistochemically examined for the expression of BRG1 , BRM , BAF47 , ARID1A , and ARID1B . The frequency at which reductions in the expression of BRG1 were observed was significantly higher in the LC‐PL group (13/38, 34.2%) than in the SCC‐AD group (7/95, 7.4%). Similarly, the frequency at which reductions in the expression of BRM were observed was significantly higher in the LC‐PL group (17/38, 44.7%) than in the SCC‐AD group (14/95, 14.7%). The loss of the expression of ARID1A , ARID1B , and BAF47 was observed only in a fraction of NSCLC cases. Furthermore, the frequency at which the concurrent loss of multiple subunits of the SWI / SNF complex was observed was significantly higher in the LC‐PL group (10/38, 26.3%) than in the SCC‐AD group (8/95, 8.4%). Collectively, these results indicate that the loss of the SWI / SNF complex was related to dedifferentiation in NSCLC .