Downregulation of tumor suppressor gene ribonuclease T2 and gametogenetin binding protein 2 is associated with drug resistance in ovarian cancer

Overcoming drug resistance in ovarian cancer through PI3K/AKT signaling inhibitors

Ovarian cancer has been identified as the eighth most typical gynaecological malignancy and cause of health problems in women. For almost forty years, platinum doublet chemotherapy has usually been the cornerstone of first-line treatment regimens. The effectiveness of conventional chemotherapy is severely hampered by relapse rates and mortality from chemotherapy resistance, which lead to the spread and recurrence of malignant cancers as well as poor outcomes in terms of quality of life in patients. Drug resistance has been linked to several mechanisms, including increased drug efflux, decreased apoptosis, increased autophagy, and changed drug metabolism. Further, the dysregulation of tumor suppressors or oncogenes plays a crucial role in chemoresistance. Additionally, PI3K/AKT/mTOR signaling has been implicated in several in vitro as well as clinical studies as a significant contributor to chemotherapy resistance in case of ovarian cancer. This review discusses the potential of various crude extracts, synthetic molecules, and nanoformulations for targeting PI3K/AKT/mTOR pathway. Moreover, a range of clinical studies involving PI3K/AKT/mTOR inhibitors have been summed up, addressing both the promises and complexities associated with their use. Overall, the review aims to provide a roadmap for future investigations that could lead to improved therapeutic outcomes for patients suffering from ovarian cancer, emphasizing the urgent need for continued exploration of novel pathways and strategies to combat drug resistance.

GGNBP2 regulates histone ubiquitination and methylation in spermatogenesis

Gametogenetin binding protein 2 (GGNBP2) was indispensable in normal spermatids for transformation into mature spermatozoa in mice, and when Gametogenetin binding protein 2 is bound to BRCC36 and RAD51, the complex participates in repairing DNA double-strand breaks (DSB) during the meiotic progression of spermatocytes. Ggnbp2 knockout resulted in the up-regulation of H2AK119ubi and down-regulation of H2BK120ubi in GC-2 cells (mouse spermatogonia-derived cell line) and postnatal day 18 testis lysate. Our results also demonstrated that Gametogenetin binding protein 2 inducedASXL1 to activate the deubiquitinating enzyme BAP1 in deubiquitinating H2A, while Gametogenetin binding protein 2 knockout disrupted the interaction between ASXL1 and BAP1, resulting in BAP1 localization change. Furthermore, the Gametogenetin binding protein 2 deletion reduced H2B ubiquitination by affecting E2 enzymes and E3 ligase binding. Gametogenetin binding protein 2 regulated H2A and H2B ubiquitination levels and controlled H3K27 and H3K79 methylation by PRC2 subunits and histone H3K79 methyltransferase. Altogether, our results suggest that Ggnbp2 knockout increased DNA damage response by promoting H2A ubiquitination and H3K27trimethylation (H3K27me3) and reduced nucleosome stability by decreasing H2B ubiquitination and H3K79 dimethylation (H3K79me2), revealing new mechanisms of epigenetic phenomenon during spermatogenesis. Gametogenetin binding protein 2 seems critical in regulating histone modification and chromatin structure in spermatogenesis.

The Potential Role of the T2 Ribonucleases in TME-Based Cancer Therapy

In recent years, there has been a growing interest in developing innovative anticancer therapies targeting the tumor microenvironment (TME). The TME is a complex and dynamic milieu surrounding the tumor mass, consisting of various cellular and molecular components, including those from the host organism, endowed with the ability to significantly influence cancer development and progression. Processes such as angiogenesis, immune evasion, and metastasis are crucial targets in the search for novel anticancer drugs. Thus, identifying molecules with "multi-tasking" properties that can counteract cancer cell growth at multiple levels represents a relevant but still unmet clinical need. Extensive research over the past two decades has revealed a consistent anticancer activity for several members of the T2 ribonuclease family, found in evolutionarily distant species. Initially, it was believed that T2 ribonucleases mainly acted as anticancer agents in a cell-autonomous manner. However, further investigation uncovered a complex and independent mechanism of action that operates at a non-cell-autonomous level, affecting crucial processes in TME-induced tumor growth, such as angiogenesis, evasion of immune surveillance, and immune cell polarization. Here, we review and discuss the remarkable properties of ribonucleases from the T2 family in the context of "multilevel" oncosuppression acting on the TME.

Bibliometric and visualized analysis of drug resistance in ovarian cancer from 2013 to 2022

Objective

As one of the cancers that seriously threatens women's health, ovarian cancer has a high morbidity and mortality rate. Surgery and chemotherapy are the basic treatment strategies for ovarian cancer, and chemotherapy resistance is a significant factor in affecting the prognosis, survival cycle, and recurrence of ovarian cancer. This article aims to analyze articles about ovarian cancer and drug resistance via bibliometric software, offering new ideas and directions for researchers in this field.

Methods

Both Citespace and Vosviewer are bibliometric software on the Java platform. Articles were collected on ovarian cancer and drug resistance in the Web of Science Core Collection database from 2013 to 2022. The countries, institutions, journals, authors, keywords, and references were analyzed, and the development status of this field was indicated from multiple perspectives.

Results

Studies on ovarian cancer and drug resistance generally showed an increasing trend from 2013 to 2022. The People's Republic of China and Chinese institutions contributed more to this field. Gynecologic Oncology published the most articles, and the journal with the most citations was Cancer Research. Li Li was the author with the most publications, and Siegel RL was the author with the most citations. Through burst detection, it can be found that the research hotspots in this field mainly focused on the in-depth exploration of the drug resistance mechanism of ovarian cancer and the progress of PARP inhibitors and bevacizumab in the treatment of ovarian cancer.

Conclusions

Many studies on the mechanism of drug resistance in ovarian cancer have been discovered; however, the deeper mechanism remains to be explored. Compared with traditional chemotherapy drugs, PARP inhibitors and bevacizumab have shown better efficacy, but PARP inhibitors have initially shown drug resistance. The future direction of this field should be to overcome the resistance of existing drugs and actively develop new ones.

HIF2α-induced upregulation of RNASET2 promotes triglyceride synthesis and enhances cell migration in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC), the most common malignant subtype of renal cell carcinoma, is characterized by the accumulation of lipid droplets in the cytoplasm. RNASET2 is a protein coding gene with a low expression level in ovarian cancers, but it is overexpressed in poorly differentiated neuroendocrine carcinomas. There is a correlation between RNASET2 upregulation and triglyceride expression levels in human serum but is unknown whether such an association is a factor contributing to lipid accumulation in ccRCC. Herein, we show that RNASET2 expression levels in ccRCC tissues and cell lines are significantly higher than those in both normal adjacent tissues and renal tubular epithelial cells. Furthermore, its upregulation is associated with increases in ccRCC malignancy and declines in patient survival. We also show that an association exists between increases in both cytoplasmic lipid accumulation and HIF-2α transcription factor upregulation, and increases in both RNASET2 and triglyceride expression levels in ccRCC tissues. In addition, DGAT1 and DGAT2, two key enzymes involved in triglyceride synthesis, are highly expressed in ccRCC tissues. By contrast, RNASET2 knockdown inhibited their expression levels and lowered lipid droplet accumulation, as well as suppressing in vitro cell proliferation, cell invasion, and migration. In conclusion, our data suggest HIF2α upregulates RNASET2 transcription in ccRCC cells, which promotes both the synthesis of triglycerides and ccRCC migration. As such, RNASET2 may have the potential as a biomarker or target for the diagnosis and treatment of ccRCC.

Fbxo45 promotes the malignant development of esophageal squamous cell carcinoma by targeting GGNBP2 for ubiquitination and degradation

Esophageal squamous cell carcinoma (ESCC) is one of the most common and deadly cancers. Fbxo45, a substrate recognition subunit of E3 ligase, is critically involved in tumorigenesis and tumor progression. However, the function of Fbxo45 and the underlying mechanisms have not been elucidated in ESCC. We used cellular and molecular methods to explore the molecular basis of Fbxo45-mediated ESCC development. We found that ectopic overexpression of Fbxo45 promoted the growth of Kyse-150, Kyse30 and ECA-109 cells and inhibited the apoptosis. Moreover, overexpression of Fbxo45 promoted the migration and invasion of ESCC cells. Consistently, knockdown of Fbxo45 exhibited the opposite effects on ESCC cells. Mechanistically, we observed that Fbxo45 binds to GGNBP2 via its SPRY domain and targets GGNBP2 for ubiquitination and degradation. GGNBP2 overexpression exhibited anticancer activity in ESCC cells. Furthermore, Fbxo45 exerted its functions by regulating GGNBP2 stability in ESCC cells. Notably, overexpression of Fbxo45 facilitated tumor growth in mice. Strikingly, Fbxo45 was highly expressed in ESCC tissues, and GGNBP2 had a lower expression in ESCC specimens. High expression of Fbxo45 and low expression of GGNBP2 were associated with poor prognosis in ESCC patients. Fbxo45 was negatively correlated with GGNBP2 expression in ESCC tissues. Therefore, Fbxo45 serves as an oncoprotein to promote ESCC tumorigenesis by targeting the stability of the tumor suppressor GGNBP2 in ESCC.

Human RNASET2: A Highly Pleiotropic and Evolutionary Conserved Tumor Suppressor Gene Involved in the Control of Ovarian Cancer Pathogenesis

Ovarian cancer represents one of the most malignant gynecological cancers worldwide, with an overall 5-year survival rate, being locked in the 25-30% range in the last decade. Cancer immunotherapy is currently one of the most intensively investigated and promising therapeutic strategy and as such, is expected to provide in the incoming years significant benefits for ovarian cancer treatment as well. Here, we provide a detailed survey on the highly pleiotropic oncosuppressive roles played by the human RNASET2 gene, whose protein product has been consistently reported to establish a functional crosstalk between ovarian cancer cells and key cellular effectors of the innate immune system (the monocyte/macrophages lineage), which is in turn able to promote the recruitment to the cancer tissue of M1-polarized, antitumoral macrophages. This feature, coupled with the ability of T2 ribonucleases to negatively affect several cancer-related parameters in a cell-autonomous manner on a wide range of ovarian cancer experimental models, makes human RNASET2 a very promising candidate to develop a "multitasking" therapeutic approach for innovative future applications for ovarian cancer treatment.

Cross‑validation of genes potentially associated with neoadjuvant chemotherapy and platinum‑based chemoresistance in epithelial ovarian carcinoma

Ovarian carcinomas have the poorest prognosis and the highest mortality among gynecological malignancies. Neoadjuvant chemotherapy (NACT) is considered as a novel therapeutic strategy and an alternative treatment for advanced epithelial ovarian cancer (AEOC). The aim of the present study was to identify the core genes related to platinum‑based NACT resistance in AEOC and to allow screening at the molecular level for the most appropriate ovarian cancer patients for NACT. We obtained three drug‑resistant microarrays GSE114206, GSE41499 and GSE33482 from the Gene Expression Omnibus (GEO) database as well as a microarray representing NACT, GSE109934. Bioinformatics analysis revealed the nature of the four potential candidate genes for using in functional enrichment analyses and interaction network construction. The potential associations and possible genetic alterations among the DEGs were summarized using the STRING database in Cytoscape and the cBioPortal visualization tool, respectively. A total of 63 genes were identified as DEGs from GSE109934 representing NACT. From the drug‑resistant GSE114206 and GSE41499 datasets, 106 DEGs containing 36 upregulated genes and 70 downregulated genes were selected, and from the drug‑resistant GSE114206 and GSE33482 datasets, 406 DEGs with 157 upregulated genes and 249 downregulated genes were selected. The 36 upregulated DEGs and the 70 downregulated genes were notably abundant in the different categories. In KEGG pathway analysis, the 157 upregulated genes and the 249 downregulated genes were concentrated in distinctive signaling pathways. Four potential genes associated with NACT and platinum‑based chemoresistance were screened, including nuclear factor of activated T‑cells, cytoplasmic 1 (NAFTc1), Kruppel‑like factor 4 (KLF4), nuclear receptor subfamily 4 group A member 3 (NR4A3) and hepatocyte growth factor (HGF). Our study showed that the mRNA expression levels of NAFTc1, NR4A3 and HGF were increased in drug‑resistant OC cell lines (all P<0.01), whereas the mRNA expression levels of KLF4 were notably lower in the SKOV3‑CDDP and HeyA8‑CDDP cell line (all P<0.01) but higher in the A2780‑CBP cell line. The NAFTc1, KLF4, NR4A3 and HGF genes may be potential therapeutic targets for NACT and platinum‑based chemoresistance factors as well as candidate biomarkers in AEOC. Determination of the expression levels of these four genes in tumor tissues before planning NACT treatment or initial surgery would be beneficial for AEOC patients.

Expression, Location, Clinical Implication, and Bioinformatics Analysis of RNASET2 in Gastric Adenocarcinoma

Background: In addition to exploiting its ribonuclease capacity, Ribonuclease T2 (RNASET2) has been reported to exert anti-angiogenic and anti-tumorigenic effects in several tumors. However, the role of RNASET2 in gastric adenocarcinoma (GAC) remains unclear. The purpose of this study was to explore the expression, location, and clinical implications of RNASET2 in GAC.

Methods: Data of RNASET2 mRNA expression in GAC and normal gastric mucosa tissues were extracted from three GSE series and 388 TCGA samples and reanalyzed. Genome-wide CRISPR/Cas9 proliferation screening datasets were used to investigate cell growth changes after RNASET2 knockout in 19 GAC cell lines. The biological processes involved in RNASET2 were studied by the bioinformatics analysis. Furthermore, the corresponding experiments including immunohistochemical staining, clinicopathological features analysis, survival curve, microvessel density detection, cell viability assay, and colony formation assay were performed to validate the expression and function of RNASET2 in GAC.

Results: An abundance of RNASET2 was present in the fundus glands and pylorus glands of the normal gastric mucosa. RNASET2 mRNA and protein were down-regulated in GAC compared with adjacent non-cancerous or normal gastric mucosa tissues. The expression of RNASET2 mRNA and protein in early GAC was higher than that in advanced GAC. 79/134 gene sets involved in the early GAC pathway were enriched in the RNASET2 mRNA high expression group. Genome-wide shRNA and CRISPR/Cas9 proliferation screening showed that knockdown or knockout of RNASET2 could not significantly promote GAC cell growth. AlamarBlue cell viability assay and colony formation assay in AGS cells further validated these results. Clinicopathologic features and survival analysis demonstrated that RNASET2 protein was significantly correlated with tumor cell differentiation, Lauren's classification, and TM4SF1 protein expression, but not correlated with lymph nodal metastasis and patient's prognosis. Microvessel density detection indicated that no significant correlation was found between the expression of RNASET2 protein and the angiogenesis of GAC.

Conclusions: Down-regulation of RNASET2 in GAC was only the consequence of the GAC, instead of the driver. The expression of RNASET2 could be regarded as a good biomarker for identifying the early stage of GAC.

Effects of gametogenetin-binding protein 2 on proliferation, invasion and migration of prostate cancer PC-3 cells

We aimed to assess the effects of gametogenetin-binding protein 2 (GGNBP2) on the proliferation, invasion and migration of prostate cancer PC-3 cells. PcDNA3-HisC-GGNBP2 was transfected to overexpress GGNBP2. Proliferation was tested by MTT assay, and migration and invasion were detected by Transwell assay. Cell cycle was detected by flow cytometry. The protein expressions of COX-2, cyclin D1, PI3K, Akt and p-Akt were detected by Western blot. A subcutaneous xenograft model of prostate cancer was established. Mice were randomly divided into three groups (n = 9) and intratumorally injected with pcDNA3-HisC-GGNBP2, pcDNA3-HisC and normal saline respectively. The xenograft tumour volume was measured every 3 days, and weight was measured after 2 weeks. After GGNBP2 overexpression, the proliferation, migration and invasion capacities of PC-3 cells decreased, and cell cycle was arrested in the G1 phase. The protein expressions of COX-2, cyclin D1, PI3K, Akt and p-Akt all reduced. The tumour volume and weight of pcDNA3-HisC-GGNBP2 group were significantly lower than those of pcDNA3-HisC group (p < .05). The proliferation capacity of GGNBP2-overexpressing prostate cancer cells is significantly attenuated, tumour growth is significantly inhibited, and cell cycle is arrested in the G1 phase. GGNBP2 overexpression affects the growth of castration-resistant prostate cancer via the PI3K/Akt signalling pathway.

GGN Promotes Tumorigenesis by Regulating Proliferation and Apoptosis in Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. GGN is a germ cell-specific gene, but its function in CRC has been rarely reported to date. The aim of this study was to investigate the potential role of GGN in CRC tumorigenesis. Therefore, in this study, we examined the expression of GGN in CRC cell lines and tissues and its effects on cellular proliferation and apoptosis. We then explored the underlying mechanism. Our results showed that GGN was significantly overexpressed in both CRC cell lines and tissues. Silencing GGN robustly inhibited proliferation of CRC cells, and it also promoted apoptosis of CRC cells. Moreover, knockdown of GGN inhibited the expression of p-Akt in CRC cells. Taken together, these results showed that knockdown of GGN inhibits proliferation and promotes apoptosis of CRC cells through the PI3K/Akt signaling pathway. Our findings revealed for the first time a potential oncogenic role for GGN in CRC progress. This finding may provide a unique perspective on how a germ cell-specific gene might serve as a biomarker, or even as a therapeutic target, for CRC.

Expression of integrin α-6 is associated with multi drug resistance and prognosis in ovarian cancer

Ovarian cancer is a serious threat to women's health. Multidrug resistance is a major cause of post-treatment relapse, metastasis, and even mortality. This characteristic severely restricts the survival of patients with ovarian cancer. Integrin α-6 (ITGA6) is a member of the adhesion molecule family that conducts signals through interactions between the extracellular domain and the matrix, serving important roles in cell adhesion-mediated drug resistance, which is considered to have a critical function in ovarian cancer drug resistance. The association between ITGA6 and ovarian cancer multidrug resistance has been investigated only rarely, to the best of our knowledge. Using RT-qPCR and immunohistochemistry, it was identified that ITGA6 is a central drug resistance gene, and that its expression was upregulated in cisplatin-resistant SKOV3 (SKOV3/DDP2), cisplatin-resistant A2780 (A2780/DDP) cells, and in 54 cases of drug-resistant tissues, as compared with in the controls. Furthermore, bioinformatics and text mining performed by Coremine Medical (http://www.coremine.com/medical/#search) confirmed that ITGA6 was significantly associated with ovarian cancer and drug resistance. Additionally, the high expression of ITGA6 is associated with a poor outcome. The present study provides the basis for further understanding the role of ITGA6 in the regulation of drug resistance in ovarian cancer, and demonstrates that it could be a potential marker for the prognosis of ovarian cancer.

GGNBP2 suppresses triple-negative breast cancer aggressiveness through inhibition of IL-6/STAT3 signaling activation

BACKGROUND

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, lacking effective targeted therapies, and whose underlying mechanisms are still unclear. The gene coding for Gametogenetin-binding protein (GGNBP2), also known as Zinc Finger Protein 403 (ZNF403), is located on chromosome 17q12-q23, a region known as a breast cancer susceptibility locus. We have previously reported that GGNBP2 functions as a tumor suppressor in estrogen receptor-positive breast cancer. The aim of this study was to evaluate the role and mechanisms of GGNBP2 in TNBC.

METHODS

The effect of GGNBP2 on TNBC aggressiveness was investigated both in vitro and in vivo. The protein and mRNA expression levels were analyzed by western blotting and reverse transcription quantitative polymerase chain reaction, respectively. Fluorescence-activated cell sorting analysis was used to evaluate the cell cycle distribution and cell apoptosis. Immunohistochemistry was used to determine the expression of GGNBP2 in breast cancer tissues.

RESULTS

We find that GGNBP2 expression decreases in TNBC tissues and is associated with the outcome of breast cancer patients. Furthermore, experimental overexpression of GGNBP2 in MDA-MB-231 and Cal51 cells suppresses cell proliferation, migration and invasion, reduces the cancer stem cell subpopulation, and promotes cell apoptosis in vitro as well as inhibits tumor growth in vivo. In these cell models, overexpression of GGNBP2 decreases the activation of IL-6/STAT3 signaling.

CONCLUSION

Our data demonstrate that GGNBP2 suppresses cancer aggressiveness by inhibition of IL-6/STAT3 activation in TNBC.

Ablation of Ggnbp2 impairs meiotic DNA double-strand break repair during spermatogenesis in mice

Gametogenetin (GGN) binding protein 2 (GGNBP2) is a zinc finger protein expressed abundantly in spermatocytes and spermatids. We previously discovered that Ggnbp2 resection caused metamorphotic defects during spermatid differentiation and resulted in an absence of mature spermatozoa in mice. However, whether GGNBP2 affects meiotic progression of spermatocytes remains to be established. In this study, flow cytometric analyses showed a decrease in haploid, while an increase in tetraploid spermatogenic cells in both 30- and 60-day-old Ggnbp2 knockout testes. In spread spermatocyte nuclei, Ggnbp2 loss increased DNA double-strand breaks (DSB), compromised DSB repair and reduced crossovers. Further investigations demonstrated that GGNBP2 co-immunoprecipitated with a testis-enriched protein GGN1. Immunofluorescent staining revealed that both GGNBP2 and GGN1 had the same subcellular localizations in spermatocyte, spermatid and spermatozoa. Ggnbp2 loss suppressed Ggn expression and nuclear accumulation. Furthermore, deletion of either Ggnbp2 or Ggn in GC-2spd cells inhibited their differentiation into haploid cells in vitro. Overexpression of Ggnbp2 in Ggnbp2 null but not in Ggn null GC-2spd cells partially rescued the defect coinciding with a restoration of Ggn expression. Together, these data suggest that GGNBP2, likely mediated by its interaction with GGN1, plays a role in DSB repair during meiotic progression of spermatocytes.

Low expression of KCNN3 may affect drug resistance in ovarian cancer

Drug resistance is a principal contributor to the poor prognosis of ovarian cancer (OC). Therefore, identifying factors that affect drug resistance in OC is critical. In the present study, 51 OC specimens from lab collections were immunohistochemically tested, public data for 489 samples from The Cancer Genome Atlas cohort and 1,656 samples from the Kaplan‑Meier Plotter were downloaded, and data were retrieved from Oncomine. It was identified that the mRNA and protein expression of the potassium calcium‑activated channel subfamily N member 3 (KCNN3) was markedly lower in OC tissues compared with normal tissues, and in drug‑resistant OC tissues compared with sensitive OC tissues. Low KCNN3 expression consistently predicted shorter disease‑free and overall survival (OS). Specifically, low KCNN3 expression predicted shorter OS in 395 patients with low expression levels of mucin‑16. There was additional evidence that KCNN3 expression is mediated by microRNA‑892b. Furthermore, text mining and analyses of protein and gene interactions indicated that KCNN3 affects drug resistance. To the best of the authors' knowledge, this is the first report to associate KCNN3 with poor prognosis and drug resistance in OC. The present findings indicated that KCNN3 is a potential prognostic marker and therapeutic target for OC.

Ggnbp2-Null Mutation in Mice Leads to Male Infertility due to a Defect at the Spermiogenesis Stage

Gametogenetin binding protein 2 (GGNBP2) is an evolutionarily conserved zinc finger protein. Although Ggnbp2-null embryos in the B6 background died because of a defective placenta, 6.8% of Ggnbp2-null mice in the B6/129 mixed background were viable and continued to adulthood. Adult Ggnbp2-null males were sterile, with smaller testes and an azoospermic phenotype, whereas mutant females were fertile. Histopathological analysis of 2-month-old Ggnbp2-null testes revealed absence of mature spermatozoa in the seminiferous tubules and epididymides and reduction of the number of spermatids. Ultrastructural analysis indicated dramatic morphological defects of developing spermatids in the Ggnbp2-null testes, including irregularly shaped acrosomes, acrosome detachment, cytoplasmic remnant, ectopic manchette, and ill-formed head shape in both elongating and elongated spermatids. However, the numbers of spermatogonia, spermatocytes, Leydig cells, and Sertoli cells in Ggnbp2-null testes did not significantly differ from the wild-type siblings. Gonadotropins, testosterone, and the blood-testis barrier were essentially unaffected. Western blot analyses showed increases in α-E-catenin, β-catenin, and N-cadherin, decreases in E-cadherin, afadin, and nectin-3, and no changes in vinculin, nectin-2, focal adhesion kinase, and integrin-β1 protein levels in Ggnbp2-null testes compared to wild-type siblings. Together, this study demonstrates that GGNBP2 is critically required for maintenance of the adhesion integrity of the adlumenal germ epithelium and is indispensable for normal spermatid transformation into mature spermatozoa in mice.

GGNBP2 is necessary for testis morphology and sperm development

Gametogenetin Binding Protein 2 (GGNBP2) was identified as a tumor suppressor and verified as such by several studies. GGNBP2 has also been reported to be essential for pregnancy maintenance via regulation of trophoblast stem cells. Gametogenetin (GGN) is a testicular germ cell-specific gene expressed in adult testes. As a potential GGN1-interacting protein, the role of GGNBP2 in spermatogenesis has not yet been clarified. We generated heterozygous GGNBP2 knockout mice and bred them by intercrossing. We found that among the offspring, homozygous GGNBP2 knockout (KO) mice were present in severely reduced numbers. The GGNBP2 KO pups developed normally, but the male siblings showed dramatically reduced fertility. In these male homozygous GGNBP2 KO mice, the only pathological finding was abnormal morphology of the testes and absence of spermatozoa. In addition, increased apoptosis was observed in the testes of GGNBP2 KO mice. SOX9 staining revealed that SOX9-positive Sertoli cells were absent in the seminiferous tubules. In homozygous mice, proliferating cell nuclear antigen (PCNA)-positive cells were localized in the lumen of the convoluted seminiferous tubules. These results suggest that GGNBP2 plays a key role in spermatogenesis by affecting the morphology and function of SOX9-positive Sertoli cells.

Guidance of Signaling Activations by Cadherins and Integrins in Epithelial Ovarian Cancer Cells

Epithelial ovarian cancer (EOC) is the deadliest tumor among gynecological cancer in the industrialized countries. The EOC incidence and mortality have remained unchanged over the last 30 years, despite the progress in diagnosis and treatment. In order to develop novel and more effective therapeutic approaches, the molecular mechanisms involved in EOC progression have been thoroughly investigated in the last few decades. At the late stage, peritoneal metastases originate from the attachment of small clusters of cancer cells that shed from the primary site and carried by the ascites adhere to the abdominal peritoneum or omentum. This behavior suggests that cell–cell or cell–matrix adhesion mechanisms regulate EOC growth and dissemination. Complex downstream signalings, which might be influenced by functional cross-talk between adhesion molecules and co-expressed and activated signaling proteins, can affect the proliferation/survival and the migration/invasion of EOC cells. This review aimed to define the impact of the mechanisms of cell–cell, through cadherins, and cell–extracellular matrix adhesion, through integrins, on the signaling cascades induced by membrane receptors and cytoplasmic proteins known to have a role in the proliferation, migration and invasion of EOC cells. Finally, some novel approaches using peptidomimetic ligands to cadherin and integrins are summarized.

GGNBP2 acts as a tumor suppressor by inhibiting estrogen receptor α activity in breast cancer cells

Gametogenetin-binding protein 2 (GGNBP2) is encoded in human chromosome 17q12-q23, a region known as a breast and ovarian cancer susceptibility locus. GGNBP2, also referred to ZFP403, has a single C2H2 zinc finger and a consensus LxxLL nuclear receptor-binding motif. Here, we demonstrate that GGNBP2 expression is reduced in primary human breast tumors and in breast cancer cell lines, including T47D, MCF-7, LCC9, LY2, and MDA-MB-231 compared with normal, immortalized estrogen receptor α (ERα) negative MCF-10A and MCF10F breast epithelial cells. Overexpression of GGNBP2 inhibits the proliferation of T47D and MCF-7 ERα positive breast cancer cells without affecting MCF-10A and MCF10F. Stable GGNBP2 overexpression in T47D cells inhibits 17β-estradiol (E2)-stimulated proliferation as well as migration, invasion, anchorage-independent growth in vitro, and xenograft tumor growth in mice. We further demonstrate that GGNBP2 protein physically interacts with ERα, inhibits E2-induced activation of estrogen response element-driven reporter activity, and attenuates ER target gene expression in T47D cells. In summary, our in vitro and in vivo findings suggest that GGNBP2 is a novel breast cancer tumor suppressor functioning as a nuclear receptor corepressor to inhibit ERα activity and tumorigenesis.

Downregulation of transient receptor potential cation channel, subfamily C, member 1 contributes to drug resistance and high histological grade in ovarian cancer

Transient receptor potential cation channel, subfamily C, member 1 (TRPC1) participates in many physiological functions but has also been implicated in cancer development. However, little is known about the role of TRPC1 in ovarian cancer (OC), including the drug resistance of these tumors. In the present study, a significant and consistent downregulation of TRPC1 in drug-resistant OC tissues/cells was determined using real-time quantitative polymerase chain reaction assays and the microarrays deposited in Oncomine and Gene Expression Omnibus (GEO) profiles. Protein/gene-protein/gene and protein-chemical interactions indicated that TRPC1 interacts with 14 proteins/genes and 6 chemicals, all of which are involved in the regulation of drug resistance in OC. Biological process annotation of TRPC1, OC, and drug resistance indicated a role for TRPC1 in drug-resistance-related functions in OC, mainly via the cell cycle, gene expression and cell growth and cell death. Analysis of mRNA-microRNA interactions showed that 8 out of 11 major pathways enriched from 38 predominant microRNAs targeting TRPC1 were involved in the regulation of drug resistance in OC, and 8 out of these top 10 microRNAs were implicated in the drug resistance in ovarian and other cancers. In a clinical analysis using data obtained from The Cancer Genome Atlas project (TCGA) cohort on 341 OC patients, TRPC1 expression was found to differ significantly between grade 2 and grade 3 tumors, with low-level expression correlating with higher tumor grade. This is the first report to show a potential association between the downregulation of TRPC1 and both drug resistance and high histological tumor grade in OC. Our results provide the basis for further investigations of the drug-resistance-related functions of TRPC1 in OC and other forms of cancer.

Discovery of microarray-identified genes associated with ovarian cancer progression

Ovarian cancer is the most lethal cancer of female reproductive system. There is a consistent and urgent need to better understand its mechanism. In this study, we retrieved 186 genes that were dysregulated by at least 4-fold in 594 ovarian serous cystadenocarcinomas in comparison with eight normal ovaries, according to The Cancer Genome Atlas Ovarian Statistics data deposited in Oncomine database. DAVID analysis of these genes enriched two biological processes indicating that the cell cycle and microtubules might play critical roles in ovarian cancer progression. Among these 186 genes, 46 were dysregulated by at least 10-fold and their expression was further confirmed by the Bonome Ovarian Statistics data deposited in Oncomine, which covered 185 cases of ovarian carcinomas and 10 cases of normal ovarian surface epithelium. Six genes, including aldehyde dehydrogenase 1 family, member A2 (ALDH1A2), alcohol dehydrogenase 1B (class I), β polypeptide (ADH1B), NEL-like 2 (chicken) (NELL2), hemoglobin, β (HBB), ATP-binding cassette, sub-family A (ABC1), member 8 (ABCA8) and hemoglobin, α1 (HBA1) were identified to be downregulated by at least 10-fold in 779 ovarian cancers compared with 18 normal controls. Using mRNA expression profiles retrieved from microarrays deposited in the Gene Expression Omnibus Profiles database, RT-qPCR measurement and bioinformatics analysis, we further indicated that high expression of HBB might predict a poorer 5-year survival, high expression of ALDH1A2 and ABCA8 might predict a poor outcome; while ALDH1A2, ADH1B, HBB and ABCA8, in particular the former two genes, might be associated with drug resistance, and ALDH1A2 and NELL2 might contribute to invasiveness and metastasis in ovarian cancer. This study thus contributes to our understanding of the mechanism of ovarian cancer progression and development, and the six identified genes may be potential therapeutic targets and biomarkers for diagnosis and prognosis.