Chromosome 8 genetic analysis and phenotypic characterization of 21 ovarian cancer cell lines

Loss of HCRP1 leads to upregulation of PD-L1 via STAT3 activation and is of prognostic significance in EGFR-dependent cancer

Loss of hepatocellular carcinoma-related protein 1 (HCRP1) (alias VPS37A) plays a role in endocytosis of receptor tyrosine kinases as a member of the ESCRT complex and has been linked to poor patient outcome in various types of epithelial cancer. To this date, the molecular and biological mechanisms explaining how its absence would contribute to tumor progression remain unknown. Using genomic editing with CRISPR-Cas9, we generated ovarian and breast cancer cell lines with loss-of-function mutations of HCRP1. We hypothesized that pathways downstream of receptor tyrosine kinases such as epidermal growth factor receptor are affected by HCRP1 loss and looked for deregulated signaling using immunoblotting and classical cancer biology assays. In our study, we show that endogenous deletion of HCRP1 leads to elevated phosphorylation of the transcription factor Signal transducer and activator of transcription 3 (STAT3) and induces upregulation of PD-L1, an important regulator of immune checkpoint inhibition. HCRP1 loss further leads to a mesenchymal phenotype switch in cancer cells, leading to increased proliferation and migration. Concludingly, our data emphasize the role of the tumor microenvironment in tumors with low or absent HCRP1 expression and suggest HCRP1 loss as a potential marker for metastatic potential and immunogenicity of epidermal growth factor receptor-driven cancer.

Five genes from chromosomal band 8p22 are significantly down-regulated in ovarian carcinoma: N33 and EFA6R have a potential impact on overall survival

BACKGROUND

Loss of heterozygosity on chromosomal band 8p22 is a common event in several epithelial tumors including ovarian carcinoma. So far, no clear evidence for a tumor suppressor gene (TSG) in this region has been found.

METHODS

On the basis of publicly available expression data in ovarian tissues, the authors selected the eight most noteworthy genes from 8p22 (DLC1, N33, ZDHHC2, FLJ32642, PDGFRL, MTSG1, PCM1, and EFA6R) for a detailed expression analysis in 58 primary ovarian carcinoma tissues and in 38 ovarian cancer cell lines by using quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR). Expression data were correlated to various clinicopathologic characteristics and survival.

RESULTS

Two genes showed a significantly (P< 0.05) lower expression in grade 3 tumors compared with tumors of lower grade (N33) or compared with normal controls and tumors with lower grade (EFA6R). Expression of N33 and EFA6R seems to have an impact on survival, in particular when the combined expression of both genes was used as predictive factor (P< 0.003). In addition, N33 and EFA6R showed a complete loss of expression in several ovarian cancer cell lines. Three genes (FLJ32642, MTSG1, and PCM1) had a significantly (P< 0.001, P< 0.004, and P< 0.001) lower expression in primary ovarian carcinoma compared with controls (ovarian tissues and cysts).

CONCLUSIONS

Two to five new potential tumor suppressor or antagonizing gene candidates (N33 and EFA6R with impact on survival, and potentially FLJ32642, MTSG1, and PCM1) for ovarian carcinoma, were identified from the chromosomal band 8p22 and are promising candidates for further functional analysis in ovarian carcinoma.

Complex CGH alterations on chromosome arm 8p at candidate tumor suppressor gene loci in breast cancer cell lines

Loss of genetic material from chromosome arm 8p occurs frequently in human breast carcinomas, consistent with this region of the genome harboring one or more tumor suppressor genes (TSGs). We used the complementary techniques of microsatellite-based LOH, high-density FISH, and conventional CGH on 6 breast cancer cell lines (MCF7, SKBR3, T47D, MDA MB453, BT549, and BT474) to investigate the molecular cytogenetic changes occurring on chromosome 8 during tumorigenesis, with particular emphasis on 6 potential TSGs on 8p. We identified multiple alterations of chromosome 8, including partial or complete deletion of 8p or 8q, duplication of 8q, and isochromosome 8q. The detailed FISH analysis showed several complex rearrangements of 8p with differing breakpoints of varying proximity to the genes of interest. High rates of LOH were observed at markers adjacent to or within PCM1, DUSP4/MKP2, NKX3A, and DLC1, supporting their status as candidate TSGs. Due to the complex ploidy status of these cell lines, relative loss of 8p material detected by CGH did not always correlate with microsatellite-based LOH results. These results extend our understanding of the mechanisms accompanying the dysregulation of candidate tumor suppressor loci on chromosome arm 8p, and identify appropriate cellular systems for further investigation of their biological properties.