The whirler mouse mutant (wi) does not respond to sound stimuli, and detailed ultrastructural analysis of sensory hair cells in the organ of Corti of the inner ear indicates that the whirler gene encodes a protein involved in the elongation and maintenance of stereocilia in both inner hair cells (IHCs) and outer hair cells (OHCs). BAC-mediated transgene correction of the mouse phenotype and mutation analysis identified the causative gene as encoding a novel PDZ protein called whirlin. The gene encoding whirlin also underlies the human autosomal recessive deafness locus DFNB31. In the mouse cochlea, whirlin is expressed in the sensory IHC and OHC stereocilia. Our findings suggest that this novel PDZ domain-containing molecule acts as an organizer of submembranous molecular complexes that control the coordinated actin polymerization and membrane growth of stereocilia.

We previously reported the construction of a P1-derived artificial chromosome (PAC) contig encompassing a set of homozygous deletions of chromosome 16q23-24.1 found in primary ovarian tumor material and several tumor cell lines. Using these PAC clones in a cDNA selection experiment, we have isolated a Sau3A fragment homologous to the WWOX transcript (GenBank accession no. AF211943) from normal human ovarian surface epithelial (HOSE) cells. We demonstrate the homozygous deletion of WWOX exons from ovarian cancer cells and three different tumor cell lines. We also identify an internally deleted WWOX transcript from a further primary ovarian tumor. In three of these samples the deletions result in frameshifts, and in each case the resulting WWOX transcripts lack part, or all, of the short chain dehydrogenase domain and the putative mitochondrial localization signal. Sequencing revealed several missense polymorphisms in tumor cell lines and identified a high level of single nucleotide polymorphism (SNP) within the WWOX gene. This evidence strengthens the case for WWOX as a tumor suppressor gene in ovarian cancer and other tumor types.

Purpose: To identify therapeutic targets in ovarian clear cell carcinomas, a chemoresistant and aggressive type of ovarian cancer. Experimental Design:Twelve ovarian clear cell carcinoma cell lines were subjected to tiling path microarray comparative genomic hybridization and genome-wide expression profiling analysis. Regions of high-level amplification were defined and genes whose expression levels were determined by copy number and correlated with gene amplification were identified. The effects of inhibition of PPM1D were assessed using short hairpin RNA constructs and a small-molecule inhibitor (CCT007093). The prevalence of PPM1D amplification and mRNA expression was determined using chromogenic in situ hybridization and quantitative real-time reverse transcription-PCR in a cohort of pure ovarian clear cell carcinomas and on an independent series of unselected epithelial ovarian cancers. Results: Array-based comparative genomic hybridization analysis revealed regions of high-level amplification on 1q32, 1q42, 2q11, 3q24-q26, 5p15, 7p21-p22, 11q13.2-q13.4, 11q22, 17q21-q22, 17q23.2,19q12-q13, and 20q13.2.Thirty-four genes mapping tothese regions displayedexpression levels that correlated with copy number gains/amplification. PPM1D had significantly higher levels of mRNA expression in ovarian clear cell carcinoma cell lines harboring gains/amplifications of17q23.2. PPM1D inhibition revealed that PPM1D expression and phosphatase activity are selectively required for the survival of ovarian clear cell carcinoma cell lines with 17q23.2 amplification. PPM1D amplification was significantly associated with ovarian clear cell carcinoma histology (P = 0.0003) and found in10% of primary ovarian clear cell carcinomas. PPM1D expression levels were significantly correlated with PPM1D gene amplification in primary ovarian clear cell carcinomas. Conclusion: Our data provide strong circumstantial evidence that PPM1D is a potential therapeutic target for a subgroup of ovarian clear cell carcinomas.Ovarian clear cell carcinoma accounts for 5% to 13% of all epithelial ovarian carcinomas (1, 2). Compared with other epithelial ovarian carcinoma subtypes, ovarian clear cell carcinomas are associated with a poorer prognosis and a relatively increased resistance to platinum-based chemotherapy (1, 3). Hence, there is a need to identify alternative and/or novel therapeutic approaches for this subgroup of epithelial ovarian carcinomas.Given its relative resistance to conventional chemotherapy, a comprehensive characterization of the molecular genetic features of ovarian clear cell carcinomas could provide clues to the mechanisms of drug resistance and identify novel therapeutic targets (4). In the context of therapeutic target discovery, inhibiting proteins whose expression is driven by gene amplification or activating genetic mutations is an effective approach (5 -7). This concept is best exemplified by the successful use of trastuzumab in the treatment of HER2-amplified breast cancer (8).Previous studies on the molecular fea...