Age-related copy number variations and expression levels of F-box protein FBXL20 predict ovarian cancer prognosis

Chromosome instability region analysis and identification of the driver genes of the epithelial ovarian cancer cell lines A2780 and SKOV3

Epithelial ovarian cancer (EOC) is one of the most prevalent gynaecological cancers worldwide. The molecular mechanisms of serous ovarian cancer (SOC) remain unclear and not well understood. SOC cases are primarily diagnosed at the late stage, resulting in a poor prognosis. Advances in molecular biology techniques allow us to obtain a better understanding of precise molecular mechanisms and to identify the chromosome instability region and key driver genes in the carcinogenesis and progression of SOC. Whole-exome sequencing was performed on the normal ovarian cell line IOSE80 and the EOC cell lines SKOV3 and A2780. The single-nucleotide variation burden, distribution, frequency and signature followed the known ovarian mutation profiles, without chromosomal bias. Recurrently mutated ovarian cancer driver genes, including LRP1B, KMT2A, ARID1A, KMT2C and ATRX were also found in two cell lines. The genome distribution of copy number alterations was found by copy number variation (CNV) analysis, including amplification of 17q12 and 4p16.1 and deletion of 10q23.33. The CNVs of MED1, GRB7 and MIEN1 located at 17q12 were found to be correlated with the overall survival of SOC patients (MED1: p = 0.028, GRB7: p = 0.0048, MIEN1: p = 0.0051), and the expression of the three driver genes in the ovarian cell line IOSE80 and EOC cell lines SKOV3 and A2780 was confirmed by western blot and cell immunohistochemistry.

Expression of CISH, an Inhibitor of NK Cell Function, Increases in Association with Ovarian Cancer Development and Progression

Epithelial ovarian cancer (OVCA), a fatal malignancy of women, disseminates locally. Although NK cells mount immune responses against OVCA, tumors inhibit NK cells, and the mechanism is not well understood. Cytokines stimulate NK cells; however, chronic stimulation exhausts them and induces expression of cytokine-inducible SH2-containing protein (CISH). Tumors produce anti-inflammatory cytokine interleukin (IL)-10 which may induce NK cell exhaustion. The goal of this study was to examine if CISH expression in NK cells increases during OVCA development and to determine the mechanism(s) of OVCA-induced CISH expression in NK cells. Normal ovaries (n = 7) were used for CISH, IL-10 and GRP78 expression. In tumor ovaries, CISH was examined in early and late stages (n = 14 each, all subtypes) while IL-10 and GRP78 expression were examined in early and late stage HGSC (n = 5 each). Compared to normal, the population of CISH-expressing NK cells increased and the intensity of IL-10 and GRP78 expression was significantly higher in OVCA (p < 0.05). CISH expression was positively correlated with IL-10 expression (r = 0.52, r = 0.65, p < 0.05 at early and late stages, respectively) while IL-10 expression was positively correlated with GRP78 expression (r = 0.43, r = 0.52, p < 0.05, respectively). These results suggest that OVCA development and progression are associated with increased CISH expression by NK cells which is correlated with tumor-induced persistent cellular stress.

TCR CDR3-antigen chemical complementarity associated with poor ovarian cancer outcomes: A vestigial immune response to early cancer antigens?

Ovarian cancer continues to present significant challenges for early detection and treatment, indicating a need for novel approaches to improve disease outcomes. In this report, we applied a previously described algorithm for detecting chemical complementarity between candidate cancer antigens and complementarity determining region-3 (CDR3) amino acid sequences from tumor resident T-cell receptors. Current literature indicates an association between high CDR3-cancer antigen complementarity and improved survival outcomes. For example, high CDR3-BRAF electrostatic complementarity is associated with a better melanoma outcome. However, such CDR3-cancer antigen chemical complementarity in ovarian cancer was largely associated with worse outcomes. Specifically, high CDR3-MAGEB4 and CDR3-TDRD1 electrostatic complementarity was associated with lower ovarian cancer disease free survival (DFS). Additionally, high CDR3-MAGEB4 and CDR3-TDRD1 electrostatic complementarity was associated with decreased MAGEB4/TDRD1 gene expression and gene copy numbers, consistent with a selection against ovarian cancer cells expressing these antigens. However, when TDRD1 was split into fragments, high CDR3-TDRD1 hydrophobicity complementarity, for a specific TDRD1 fragment, was associated with increased DFS and higher immune marker expression levels. This dichotomy highlights the myriad of opportunities to establish risk stratifications and to identify potential, actionable cancer antigens using immunogenomic parameters.

Genome-wide interrogation of structural variation reveals novel African-specific prostate cancer oncogenic drivers

BACKGROUND

African ancestry is a significant risk factor for advanced prostate cancer (PCa). Mortality rates in sub-Saharan Africa are 2.5-fold greater than global averages. However, the region has largely been excluded from the benefits of whole genome interrogation studies. Additionally, while structural variation (SV) is highly prevalent, PCa genomic studies are still biased towards small variant interrogation.

METHODS

Using whole genome sequencing and best practice workflows, we performed a comprehensive analysis of SVs for 180 (predominantly Gleason score ≥ 8) prostate tumours derived from 115 African, 61 European and four ancestrally admixed patients. We investigated the landscape and relationship of somatic SVs in driving ethnic disparity (African versus European), with a focus on African men from southern Africa.

RESULTS

Duplication events showed the greatest ethnic disparity, with a 1.6- (relative frequency) to 2.5-fold (count) increase in African-derived tumours. Furthermore, we found duplication events to be associated with CDK12 inactivation and MYC copy number gain, and deletion events associated with SPOP mutation. Overall, African-derived tumours were 2-fold more likely to present with a hyper-SV subtype. In addition to hyper-duplication and deletion subtypes, we describe a new hyper-translocation subtype. While we confirm a lower TMPRSS2-ERG fusion-positive rate in tumours from African cases (10% versus 33%), novel African-specific PCa ETS family member and TMPRSS2 fusion partners were identified, including LINC01525, FBXO7, GTF3C2, NTNG1 and YPEL5. Notably, we found 74 somatic SV hotspots impacting 18 new candidate driver genes, with CADM2, LSAMP, PTPRD, PDE4D and PACRG having therapeutic implications for African patients.

CONCLUSIONS

In this first African-inclusive SV study for high-risk PCa, we demonstrate the power of SV interrogation for the identification of novel subtypes, oncogenic drivers and therapeutic targets. Identifying a novel spectrum of SVs in tumours derived from African patients provides a mechanism that may contribute, at least in part, to the observed ethnic disparity in advanced PCa presentation in men of African ancestry.

F-Box and Leucine-Rich Repeat Protein 20 (FBXL20), Negatively Regulated by microRNA (miR)-195-5p, Accelerates the Malignant Progression of Ovarian Cancer

Ovarian cancer (OC) is one of the most common cancers among women, characterized by various histological subtypes. Here, we aimed to investigate the biological function of F-box and leucine-rich repeat protein 20 (FBXL20) in the malignant phenotype of OC cells and its related mechanism. The expression of FBXL20 in OC tissue and normal tissue samples was analyzed through the GEPIA database. Quantitative real-time PCR (qRT-PCR), immunohistochemistry (IHC) and Western blot were employed to detect the expression of miR-195-5p and FBXL20 in OC tissues and cell lines. Cell counting kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) experiment and flow cytometry were applied to detect cell proliferation, cell cycle and apoptosis. Bioinformatics analysis and dual-luciferase reporter gene experiments were adopted to predict and validate the targeting relationship between miR-195-5p and FBXL20 mRNA 3'-untranslated region (3'UTR). Correlation between the expressions of miR-195-5p and FBXL20 mRNA was analyzed by Pearson correlation analysis. FBXL20 expression was upregulated in OC, and its high expression level was significantly associated with higher International Federation of Gynecology and Obstetrics (FIGO) stage and poor tumor differentiation. Functionally, overexpression of FBXL20 promoted proliferation, inhibited apoptosis and accelerated the cell cycle in OC cells in comparison to control group, and knockdown of FBXL20 exerted the opposite effects. Mechanistically, miR-195-5p directly targeted FBXL20 and negatively regulated its expression. Pearson correlation analysis indicated that miR-195-5p was negatively correlated with FBXL20 mRNA expression. In addition, overexpression of miR-195-5p reversed the above biological functions of FBXL20 in OC cells. FBXL20, negatively regulated by miR-195-5p, accelerates the proliferation and cell cycle progression of OC cells, and inhibits cell apoptosis, which might act as a prospective prognostic biomarker and a promising therapeutic target for OC.

F-box proteins in cancer stemness: An emerging prognostic and therapeutic target

Cancer is a complex heterogenic disease with significant therapeutic challenges. The presence of cancer stem cells (CSCs) in cancer tissue orchestrates tumor growth, progression, and metastasis, the tumor heterogeneity, disease relapse, and therapeutic resistance. Hence, it is imperative to explore how progenitor or cancer-initiating cells acquire stemness features and reprogram different biological mechanisms to maintain their sustained oncogenicity. Interestingly, deregulation of F-box proteins (FBPs) is crucial for cancer stemness features, including drug resistance and disease relapse. In this review, we highlight recent updates on the clinical significance of targeting FBPs in cancer therapy, with emphasis on eliminating CSCs and associated therapeutic challenges. Moreover, we also discuss novel strategies for the selective elimination of CSCs by targeting FBPs.