Inactivating mutations of CASPASE-7 gene in human cancers Young Hwa Soung 1 , Jong Woo Lee 1 , Hong Sug Kim 1 , Won Sang Park 1 , Su Young Kim 1 , Jong Heun Lee 1 , Jik Young Park 1 , Yong Gu Cho 1 , Chang Jae Kim 1 , Yong Gyu Park 2 , Suk Woo Nam 1 , Seong Whan Jeong 3 , Sang Ho Kim 1 , Jung Young Lee 1 , Nam Jin Yoo 1 and Sug Hyung Lee* ,1 1 Department of Pathology, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea; 2 Department of Biostatistics, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea; 3 Department of Biochemistry, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea Caspase-7 is a caspase involved in the execution phase of apoptosis. To explore the possibility that the genetic alterations of CASPASE-7 might be involved in the development of human cancers, we analysed the entire coding region and all splice sites of human CASPASE-7 gene for the detection of somatic mutations in a series of human solid cancers, including carcinomas from stomach, colon, head/neck, esophagus, urinary bladder and lung. Overall,wedetected CASPASE-7 mutationsintwoof98 colon carcinomas (2.0%), one of 50 esophageal carcino- mas(2.0%)andoneof33head/neckcarcinomas(3.0%). We expressed the tumor-derived caspase-7 mutants in 293T cells and found that the apoptosis was reduced compared to the wild-type caspase-7. This is the first report on the CASPASE-7 gene mutations in human malignancies, and our data suggest that the inactivating mutationsofthe CASPASE-7 genemightleadtotheloss of its apoptotic function and contribute to the pathogen- esis of some human solid cancers. Oncogene (2003) 22, 8048–8052. doi:10.1038/sj.onc.1206727 Keywords: CASPASE-7; mutation; solid cancer; apop- tosis; caspases Apoptosis is a fundamental biochemical cell-death pathway essential for normal tissue homeostasis, cellular differentiation and development (Reed, 2000). Proteases cause the morphological changes that are recognized as apoptosis and the biochemical changes associated with apoptosis (Nicholson, 1999). Among the proteases, a family of cysteine proteases that cleave the substrates at aspartate residues, known as caspases, plays a main role during apoptosis (Nicholson, 1999; Reed, 2000). The caspase gene family thus far contains at least 14 mammalian members, of which 12 human enzymes are known (Nicholson, 1999). From a functional perspec- tive, the caspase gene family has been classified into either initiator caspases or effector caspases. The initiator caspases would appear to be caspase-2, -8, -9 and -10, and the effector caspases would appear to be caspase-3, -6 and -7 (Nicholson, 1999). The effector caspases are thought to be responsible for the actual destruction of the cell. Caspase-7 is highly related to caspase-3, and these two caspases are activated by both death receptor- and mitochondria-induced apoptosis (Tewari et al., 1995; Duan et al., 1996; Pai et al., 1996; Lippke et al., 1996; Slee et al., 2001). The initiator caspases-8 and -9 can process pro-caspase-7 by cleavage, giving rise to p23 and p12 subunits (Hirata et al., 1998; Slee et al., 1999). It is now believed that clonal expansion and tumor growth are the results of the deregulation of intrinsic proliferation (cell division) and cell death (apoptosis) (Hanahan and Weinberg, 2000). Failure of apoptosis could allow the survival of transformed cells that are prone to undergo further genetic damage and play an important role in the pathogenesis of tumors. Either inactivation of proapoptotic pathway or activation of antiapoptotic pathway results in failure of apoptosis, thereby promoting tumor cell survival. There has been evidence that alterations of caspases participate in tumor development (Mandruzzato et al., 1997; Kurokawa et al., 1999; Lee et al., 1999; Schwartz et al., 1999; Palmerini et al., 2001; Shin et al., 2002). In vitro studies showed that resistance to apoptosis in some cancer cell lines correlates with losses of caspases (Kurokawa et al., 1999). Also, an immunohistochemical study revealed downregulation of caspase-7 in colon cancer samples compared with normal colon mucosa (Palmerini et al., 2001). In addition, epigenetic mod- ification of CASPASE-8 by DNA methylation has recently been implied in loss of caspase-8 function in several solid tumors of childhood (Teitz et al., 2000; Fulda et al., 2001). Mutations of the genes involved in apoptosis, including the death receptors and caspases, have been reported in human cancers, implying that the somatic mutations of apoptosis-related genes may not be a rare event in the cancer pathogenesis (Mandruzzato et al., 1997; Kurokawa et al., 1999; Lee et al., 1999; Schwartz et al., 1999; Shin et al., 2002). Among the caspases, somatic mutations of CASPASE-3, -5, -8 and -10 have been reported in human cancer tissues and cell lines (Mandruzzato et al., 1997; Kurokawa et al., 1999; Schwartz et al., 1999; Fulda et al., 2001; Shin et al., 2002). Most of the caspase mutations detected in human Received 5 February 2003; revised 8 April 2003; accepted 16 April 2003 *Correspondence: SH Lee, E-mail: suhulee@cmc.cuk.ac.kr Oncogene (2003) 22, 8048–8052 & 2003 Nature Publishing Group All rights reserved 0950-9232/03 $25.00 www.nature.com/onc