Abstract 4858: Identification of ZDHHC14 as a novel tumor suppressor gene commonly downregulated in human cancers
Authors: Yeste-Velasco Marc , Mao X. , Grose R. , Kudahetti S.C. , Lin D. , Chaplin T. , Xue L. , Xu M. , Foster J.M. , James S. , Chioni A.M. , Jeetle S. , Vasiljević N.A. , Marzec J. , Gould D. , Jones L. , Lorincz A.T. , Oliver R. T. D. , Mather S.J. , Shipley J.M. , Berney D.M. , Young B.D. , Lu Y-J. 
Published: August 2012

Abstract
Tumor suppressor genes (TSGs) play critical roles in preventing tumorigenesis and they are frequently inactivated in tumours. Recently developed high-density microarrays can detect subchromosomal deletions, recurrence of which usually indicates the location of TSGs within the deleted region. We analyzed testicular germ cell tumour (TGCT) clinical samples using SNP arrays and found a frequent small deletion on the region 6q25.3 containing only one known gene, ZDHHC14. While its cellular function is unknown, ZDHHC14 belongs to the recently discovered DHHC family, which are predicted to be involved in protein palmitoylation, a reversible lipid modification that regulates membrane tethering for key proteins in cell signaling, cancer, neuronal transmission, and membrane trafficking. Consistently, we found a dramatic under-expression of ZDHHC14 mRNA and protein in TGCTs, and this associated with chemoresistance. Oncomine database mining showed that ZDHHC14 is also under-expressed in lymphoma, liposarcoma, brain, kidney, lung and colorectal cancers. Thus, it appears that ZDHHC14 downregulation may be involved in other cancers. We studied ZDHHC14 expression in prostate cancer (PCa), detecting a decrease at mRNA and protein level. We also detected that ZDHHC14 mRNA was downregulated in a pilot study on breast cancer samples. As genomic loss of the ZDHHC14 region was only detected in a small number of PCa samples, we checked whether promoter hypermethylation was the cause for ZDHHC14 downregulation. However, no changes in methylation status were found. We then sequenced the whole genomic region surrounding ZDHHC14 by next generation sequencing in TGCTs and PCa and found several mutations in the promoter, the coding region, as well as in intronic regions. Finally, we tested the function of ZDHHC14 in cell-based studies. We generated a 293 T-REx tetracycline inducible ZDHHC14 overexpressing stable cell line, which showed that ZDHHC14 overexpression decreased cell viability. The induction of apoptosis by ZDHHC14 overexpression was detected both by FACS and caspase 7 and PARP cleavage analyses. This was confirmed by transient ZDHHC14 overexpression in the PCa cell line 22RV1. In vivo we xenografted mice using both tetracycline inducible ZDHHC14 overexpressing 293 T-REx cells and control cells transfected with the empty vector. ZDHHC14 expression was induced by tetracycline at the beginning of inoculation and we detected that ZDHHC14 overexpression blocked tumour initiation completely. In conclusion, these results implicate ZDHHC14 as a tumour suppressor gene commonly inactivated in human cancers, indicating that it might exert its tumor suppressor role through the induction of programmed cell death. This is the first study showing the involvement of ZDHHC14 in a specific pathway, the classic caspase-dependent apoptosis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4858. doi:1538-7445.AM2012-4858