Ovarian Progression Research Articles

The role of molecular subtypes and immune infiltration characteristics based on disulfidptosis-related genes in ovarian cancer

Ovarian cancer (OC) is the most fatal, gynecological malignancy. Compared with advanced ovarian cancer, the 5 year survival rate of early ovarian cancer is significantly improved, and predicting early detection and diagnosis is very important to improve the prognosis of OC. Recent research has found a new way of cell death: disulfidptosis. Under glucose starvation, abnormal accumulation of disulfide molecules such as Cystine in SLC7A11 overexpression cells induced disulfide stress to trigger cell death. Studies of disulfidptosis are still in their infancy and its role in ovarian cancer progression is unclear. In this study, we used a public database to detect the expression and mutations of disulfidptosis-related genes in OC. Cluster analysis was performed based on disulfidptosis-related genes, and disulfidptosis differential expression genes were analyzed. A prognostic risk model was constructed using three disulfidptosis-related genes, and the reasons for differences in prognosis were explored through immune infiltration analysis and drug sensitivity analysis. The prognostic characteristics of transcriptome based on disulfidptosis-related genes are closely related to the prognosis of OC patients. Finally, quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of three prognostic genes in clinical OC samples.Our study establishes a link between disulfidptosis and OC, providing new ideas for personalized and precise treatment of OC.

Long Non-coding RNA FOXD2-AS1 Silencing Inhibits Malignant Behaviors of Ovarian Cancer Cells Via miR-324-3p/SOX4 Signaling Axis.

It is urgent to develop new therapeutic strategies for ovarian cancer (OC). Long-noncoding RNAs (lncRNAs) have participated in multiple biological processes including tumor recurrence and progression. This study aimed to determine the effects and potential regulatory mechanism of lncRNA FOXD2-AS1 in OC progression. Levels of lncRNA FOXD2-AS1 and miR-324-3p in OC tissues and cell lines were analyzed using quantitative real-time PCR (qRT-PCR). The direct target between FOXD2-AS1 or miR-324-3p was determined using bioinformatics tools and further verified by dual-luciferase reporter assay. Cell viability, apoptosis, migration, along invasion were assessed by MTT, flow cytometry, as well as Transwell assays, respectively. In addition, the levels of miR-324-3p, PCNA, MMP9, Bax, Bcl-2, and SOX4 in OC cells were evaluated using qRT-PCR and western blot assays. We observed that lncRNA FOXD2-AS1 was up-regulated while miR-324-3p was down-regulated in OC tissues and cell lines, especially in SKOV3 cells. Moreover, miR-324-3p was a direct target of lncRNA FOXD2-AS1. Meanwhile, SOX4 interacted with miR-324-3p and was negatively regulated by miR-324-3p in SKOV3 cells. Function assays confirmed that lncRNA FOXD2-AS1 silenced depressed cell proliferation, migration, and invasion while accelerating apoptosis. These functions of lncRNA FOXD2-AS1 were attenuated by miR-324-3p inhibition. Our research demonstrated that FOXD2-AS1 silencing restrained cell growth and metastasis of OC via regulating miR-324-3p/SOX4 axis, indicating that lncRNA FOXD2-AS1 could be a novel potential therapeutic target for OC.

Effects of Thyroid Hormones on Cellular Development in Human Ovarian Granulosa Tumor Cells (KGN).

Ovarian cancer is a common malignant tumor in the female reproductive system, and Granulosa cell tumor (GCT) of the ovary is a rare type of ovarian cancer, which significantly threatens women's reproductive health. It has been reported that dysregulation of thyroid hormones (THs) may be closely related to the progression and prognosis of ovarian cancer. Moreover, THs regulate phosphorylation of signal transducer and activator of transcription (STAT3) and Octamer-binding transcription factor 4 (OCT4) expression. It has been reported that STAT3 and OCT4 play important roles in cellular development and tumorigenesis. However, the mechanisms by which THs affect the development of GCT are still remained unclear. To evaluate the effect of THs on human ovarian granulosa tumor cells (KGN), cells were treated with 3,5,3' -triiodothyronine (T3). Oct4 small interfering (Oct4 siRNA) or STAT3 inhibitor C188-9 was also co-cultured with cells in some experiments, respectively. The cell viability, proliferation, and proteins content were detected by CCK-8, EdU, and Western Blotting, respectively. The results showed that T3 enhanced cell viability and proliferation. Moreover, T3 also increased the expression of thyroid hormone receptor (TR), p-STAT3, and OCT4 proteins. The effects of T3 on both p-STAT3 and OCT4 expression were blocked by TR antagonist 1-850. Meanwhile, C188-9, an inhibitor of STAT3, decreased T3-induced cellular viability, proliferation, and OCT4 expression, highlighting that p-STAT3 can regulate the expression of OCT4 and affect cellular viability, and proliferation. Furthermore, T3-induced cellular growth was reduced by Oct4 siRNA, which indicates that T3 regulates cellular development through OCT4. These findings suggest that T3 increases cellular development via OCT4, which is mediated by phosphorylation of STAT3, and TR is also involved in these processes.

SHCBP1 promotes cisplatin resistance of ovarian cancer through AKT/mTOR/Autophagy pathway.

Ovarian cancer caused the highest cancer-related mortality among female reproductive system malignancies. Platinum-based chemotherapy is still the footstone of the chemotherapy for ovarian cancer. However, the molecular mechanisms underlying cisplatin insensitivity and resistance remain unclear. SHC SH2 domain-binding protein 1 (SHCBP1) plays critical roles in the progression and drug resistance of different types of cancer. However, the biological function of SHCBP1 in ovarian cancer progression and cisplatin resistance remains obscure. In this study, we found that SHCBP1 was upregulated in ovarian cancer and the upregulated SHCBP1 has growth-promoting effect on ovarian cancer cells. Furthermore, SHCBP1 silencing sensitize ovarian cancer cells to cisplatin (hereafter referred to as CDDP). Mechanism analysis revealed that SHCBP1 activated the Akt/mTOR pathway and further inhibited autophagy in ovarian cancer cells. Meanwhile, autophagy inhibitors combined with SHCBP1 knockdown enhances CDDP sensitivity. In addition, knockdown of SHCBP1 restricted the proliferation of tumors and increased the cisplatin sensitivity in vivo. These findings suggested that upregulated SHCBP1 promoted the proliferation and CDDP resistance of ovarian cancer. The combination of SHCBP1 inhibition and cisplatin treatment might lead to substantial progress in ovarian cancer targeted therapy.

MIR937 amplification potentiates ovarian cancer progression by attenuating FBXO16 inhibition on ULK1-mediated autophagy

High-grade serous ovarian carcinoma (HGSOC) is one of the most lethal gynecological cancer. Genetic studies have revealed gene copy number alterations (CNAs) frequently occurred in HGSOC pathogenesis, however the function and mechanism of CNAs for microRNAs are still not fully understood. Here, we show the dependence on gene copy number amplification of MIR937 that enhances cell autophagy and dictates HGSOC proliferative activity. Data mining of TCGA database revealed MIR937 amplification is correlated with increased MIR937 expression and cell proliferation of HGSOC. Deletion of MIR937 in HGSOC cells led to impaired autophagy and retarded cell proliferation, and the extent for its inhibitory effects scaled with the degree of MIR937 copy loss. Rescue assay confirmed miR-937-5p, a mature product of MIR937, was sufficient to restore its oncogenic function. Mechanistically, MIR937 amplification raised the expression of miR-937-5p, enhanced its binding to 3′ UTR of FBXO16 transcript, and thereby restricting FBXO16 degradative effects on ULK1. Our results demonstrate that MIR937 amplification augments cell autophagy and proliferation, and suggest an alternative strategy of MIR937/FBXO16/ULK1 targeting for HGSOC treatment.

Inhibition of HOXC11 by artesunate induces ferroptosis and suppresses ovarian cancer progression through transcriptional regulation of the PROM2/PI3K/AKT pathway

BackgroundFerroptosis, a non-apoptotic form of regulated cell death, plays a critical role in the suppression of various tumor types, including ovarian cancer. Artesunate (ART), a derivative of artemisinin, exhibits extensive antitumor effects and is associated with ferroptosis. This study aimed to investigate the mechanisms through which ART induces ferroptosis to inhibit ovarian cancer.MethodsRNA sequencing was conducted to identify differentially expressed genes associated with ART-induced ferroptosis. Dual-luciferase reporter assays and electrophoretic mobility shift assays were performed to confirm the interaction between Homeobox C11 (HOXC11) and the Prominin 2 (PROM2) promoter. Cell Counting Kit-8 (CCK-8) assays, flow cytometry, and wound healing assays were used to analyze the antitumor effects of ART. Western blot, biochemical assays and transmission electron microscope were utilized to further characterize ART-induced ferroptosis. In vivo, the effects of ART on ferroptosis were examined using a xenograft mouse model.ResultsRNA sequencing analysis revealed that the HOXC11, PROM2 and Phosphatidylinositol 3-Kinase/ Protein Kinase B (PI3K/AKT) pathways were downregulated by ART. HOXC11 was found to regulate PROM2 expression by binding to its promoter directly. HOXC11 overexpression reversed ART-induced effects on ovarian cancer cell proliferation, migration, apoptosis and ferroptosis by activating the PROM2/PI3K/AKT signaling axis. Conversely, silencing PROM2 in HOXC11-overexpressing cells restored ART-induced ferroptosis and its associated antitumor effects by inhibiting the PI3K/AKT pathway. Consistently, in vivo studies using a xenograft mouse model confirmed that ART-induced tumor inhibition was mediated by ferroptosis through the suppression of the HOXC11/PROM2/PI3K/AKT pathway.ConclusionThis study identifies the HOXC11/PROM2/PI3K/AKT axis as a novel regulatory mechanism underlying ART-induced ferroptosis in ovarian cancer. Targeting the HOXC11/PROM2 axis may represent a promising therapeutic strategy for enhancing ferroptosis, offering new insights for the treatment of ovarian cancer.

GOG-3097/ENGOT-ov81/GTG-UK/RAMP 301: a phase 3, randomized trial evaluating avutometinib plus defactinib compared with investigator’s choice of treatment in patients with recurrent low grade serous ovarian cancer

BackgroundThere are no approved treatments specifically for low grade serous ovarian cancer; current standard of care treatment options are limited in efficacy and tolerability. The combination of avutometinib with defactinib...

Hypermethylation in Ovarian Cancer of Long Non-Coding RNA Genes: <i>HOTAIR</i>, <i>GAS5</i>, <i>LINC00472</i>, <i>LINC00886</i>, <i>TUG1</i>

Recently, more and more data have been accumulating indicating the role of long non-coding RNAs (lncRNAs) in the regulation of biological processes in cells, as well as in the mechanisms of cancer development and progression. Aberrant methylation of promoter regions of both protein genes and lncRNA genes can disrupt their expression and functional activity. Using bioinformatics databases, six lncRNA genes (GAS5, HOTAIR, LINC00472, LINC00886, SNHG17 and TUG1) with CpG islands, differentially expressed and presumably hypermethylated in tumors of patients with ovarian cancer (OC) were selected. A statistically significant (p 0.05) increase in the methylation level in tumours was demonstrated in a sample of 93 OC specimens using methylation-specific real-time PCR assay. Moreover, for the genes LINC00472, LINC00886, SNHG17 and TUG1, hypermethylation in OC was detected for the first time. 5 genes (except SNHG17) showed a further increase in methylation levels at a more advanced stage, and 4 genes (except SNHG17 and LINC00886) showed a significant association with metastasis. Using real-time RT-PCR, differential changes in the expression level of the GAS5, HOTAIR, SNHG17 and TUG1 genes and a significant correlation of methylation with expression for the GAS5 gene were shown. Thus, hypermethylation associated with the progression and/or development of OC was detected for six lncRNA genes, which is important for elucidating the epigenetic processes involved in the pathogenesis of OC and can be used as new biomarkers of OC.

DCAF13 promotes ovarian cancer progression by activating FRAS1-mediated FAK signaling pathway

Cullin-RING ubiquitin ligase 4 (CRL4) is closely correlated with the incidence and progression of ovarian cancer. DDB1- and CUL4-associated factor 13 (DCAF13), a substrate-recognition protein in the CRL4 E3 ubiquitin ligase complex, is involved in the occurrence and development of ovarian cancer. However, its precise function and the underlying molecular mechanism in this disease remain unclear. In this study, we confirmed that DCAF13 is highly expressed in human ovarian cancer and its expression is negatively correlated with the overall survival rate of patients with ovarian cancer. We then used CRISPR/Cas9 to knockout DCAF13 and found that its deletion significantly inhibited the proliferation, colony formation, and migration of human ovarian cancer cells. In addition, DCAF13 deficiency inhibited tumor proliferation in nude mice. Mechanistically, CRL4-DCAF13 targeted Fraser extracellular matrix complex subunit 1 (FRAS1) for polyubiquitination and proteasomal degradation. FRAS1 influenced the proliferation and migration of ovarian cancer cell through induction of the focal adhesion kinase (FAK) signaling pathway. These findings collectively show that DCAF13 is an important oncogene that promotes tumorigenesis in ovarian cancer cells by mediating FRAS1/FAK signaling. Our findings provide a foundation for the development of targeted therapeutics for ovarian cancer.

Ironing Out the Kinks: Arming Natural Killer Cells against Ovarian Cancer.

Ameliorating the tumor immune microenvironment is a key strategy to improve the therapeutic outcomes of patients with cancer. Sandoval and colleagues demonstrate that iron chelation enhances type I IFN production, promotes NK cell tumor trafficking and activation, and synergizes with chemotherapy drug cisplatin to reduce metastatic ovarian cancer progression in murine models. See related article by Sandoval et al., p. 1901.

SLC45A4 is involved in malignant progression of ovarian cancer through glycolytic metabolic reprogramming

Tumor cells promote malignant behaviors such as proliferation, invasion, and metastasis of cancer cells through glucose metabolic reprogramming, but the role of the H-dependent sugar cotransporter SLC45A4 in regulating metabolic reprogramming in ovarian cancer (OC) remains largely unknown. This study aimed to investigate the effects of SLC45A4 silencing on the transcriptome spectrum of ovarian cancer cells (OCC), glucose uptake, lactic acid production, intracellular ATP levels, and the expression and activity of HIF-α glycolysis signaling pathway. The results showed that SLC45A4 is overexpressed in OC and its elevated expression correlates with adverse clinical outcomes in OC patients. Silencing of SLC45A4 significantly inhibited the proliferation, invasion, and metastasis of OCC by suppressing glucose uptake and glycolysis, and it also reduced the expression of HIF-α glycolysis signaling pathway in OC tissues. In vivo experiments using shRNA to knock down SLC45A4 in xenograft models in nude mice demonstrated a significant inhibition of tumor growth. These findings suggest that SLC45A4 silencing can restrain the malignant progression of OC by inhibiting glucose uptake in OCC and affecting the reprogramming of glycolytic energy metabolism, indicating that SLC45A4 may serve as a potential therapeutic target for OC intervention.

ZFHX2-AS1 interacts with DKC1 to regulate ARHGAP5 pseudouridylation and suppress ovarian cancer progression

Ovarian cancer (OCa) remains a highly lethal disease, largely due to late-stage diagnosis and limited treatment options for recurrent metastatic tumors. Long non-coding RNAs (lncRNAs) have been recognized as key regulators of cancer hallmarks, yet their specific roles in driving OCa progression are not fully understood. In this study, we employed an integrated approach combining clinical correlation, functional assays, and mechanistic investigations to reveal that lncRNA ZFHX2-AS1 is significantly downregulated in OCa tissues and cells, with its reduced expression associated with poor clinical outcomes. Using in vitro and in vivo models, we demonstrated that overexpression of ZFHX2-AS1 suppresses OCa cell proliferation, migration and invasion, whereas ZFHX2-AS1 knockdown enhances these malignant phenotypes. Mechanistically, we defined that ZFHX2-AS1 interacts with and attenuates the enzymatic activity of the pseudouridine synthase DKC1, thereby reducing pseudouridylation and stabilizing the oncogenic ARHGAP5 mRNA. Re-expression of ARHGAP5 could partially reverse the tumor-suppressive effects of ZFHX2-AS1. Further, we found that ARHGAP5 promotes epithelial-mesenchymal transition (EMT) by regulating Rho GTPases activities, and that ZFHX2-AS1 inhibits EMT in OCa by downregulating ARHGAP5 expression and suppressing the Rho GTPase signaling pathway. Taken together, our findings identify ZFHX2-AS1 as a potent tumor suppressor in OCa, acting through the modulation of DKC1-mediated pseudouridylation of ARHGAP5 and the inhibition of the Rho GTPase pathway, thus offering a potential therapeutic target for combating OCa progression.

YKL40/Integrin β4 Axis Induced by the Interaction between Cancer Cells and Tumor-Associated Macrophages Is Involved in the Progression of High-Grade Serous Ovarian Carcinoma.

Macrophages in the tumor microenvironment, termed tumor-associated macrophages (TAMs), promote the progression of various cancer types. However, many mechanisms related to tumor-stromal interactions in epithelial ovarian cancer (EOC) progression remain unclear. High-grade serous ovarian carcinoma (HGSOC) is the most malignant EOC subtype. Herein, immunohistochemistry was performed on 65 HGSOC tissue samples, revealing that patients with a higher infiltration of CD68+, CD163+, and CD204+ macrophages had a poorer prognosis. We subsequently established an indirect co-culture system between macrophages and EOC cells, including HGSOC cells. The co-cultured macrophages showed increased expression of the TAM markers CD163 and CD204, and the co-cultured EOC cells exhibited enhanced proliferation, migration, and invasion. Cytokine array analysis revealed higher YKL40 secretion in the indirect co-culture system. The addition of YKL40 increased proliferation, migration, and invasion via extracellular signal-regulated kinase (Erk) signaling in EOC cells. The knockdown of integrin β4, one of the YKL40 receptors, suppressed YKL40-induced proliferation, migration, and invasion, as well as Erk phosphorylation in some EOC cells. Database analysis showed that high-level expression of YKL40 and integrin β4 correlated with a poor prognosis in patients with serous ovarian carcinoma. Therefore, the YKL40/integrin β4 axis may play a role in ovarian cancer progression.

Chemotherapy Enriches for Proinflammatory Macrophage Phenotypes that Support Cancer Stem-Like Cells and Disease Progression in Ovarian Cancer.

High-grade serous ovarian cancer remains a poorly understood disease with a high mortality rate. Although most patients respond to cytotoxic therapies, a majority will experience recurrence. This may be due to a minority of drug-resistant cancer stem-like cells (CSC) that survive chemotherapy and are capable of repopulating heterogeneous tumors. It remains unclear how CSCs are supported in the tumor microenvironment (TME) particularly during chemotherapy exposure. Tumor-associated macrophages (TAM) make up half of the immune population of the ovarian TME and are known to support CSCs and contribute to cancer progression. TAMs are plastic cells that alter their phenotype in response to environmental stimuli and thus may influence CSC maintenance during chemotherapy. Given the plasticity of TAMs, we studied the effects of carboplatin on macrophage phenotypes using both THP1- and peripheral blood mononuclear cell (PBMC)-derived macrophages and whether this supports CSCs and ovarian cancer progression following treatment. We found that carboplatin exposure induces an M1-like proinflammatory phenotype that promotes SOX2 expression, spheroid formation, and CD117+ ovarian CSCs, and that macrophage-secreted CCL2/MCP-1 is at least partially responsible for this effect. Depletion of TAMs during carboplatin exposure results in fewer CSCs and prolonged survival in a xenograft model of ovarian cancer. This study supports a role for platinum-based chemotherapies in promoting a transient proinflammatory M1-like TAM that enriches for CSCs during treatment. Improving our understanding of TME responses to cytotoxic drugs and identifying novel mechanisms of CSC maintenance will enable the development of better therapeutic strategies for high-grade serous ovarian cancer. Significance: We show that chemotherapy enhances proinflammatory macrophage phenotypes that correlate with ovarian cancer progression. Given that macrophages are the most prominent immune cell within these tumors, this work provides the foundation for future translational studies targeting specific macrophage populations during chemotherapy, a promising approach to prevent relapse in ovarian cancer.

The lncRNA TPTEP1 suppresses PI3K/AKT signalling and inhibits ovarian cancer progression by interacting with PTBP1.

The expression of the long noncoding RNA (lncRNA) TPTE pseudogene 1 (TPTEP1) is significantly downregulated in ovarian cancer (OC). However, the function and mechanism of the lncRNA TPTEP1 in OC have not been identified. To investigate the expression of the lncRNA TPTEP1, we analysed a publicly available dataset and 20 pairs of OC and normal ovarian samples tissue from the First Affiliated Hospital of Anhui Medical University. Functional assays were used to determine the role of the lncRNA TPTEP1 in OC progression. Furthermore, Western blot, FISH, RNA pull-down, mass spectrometry and RNA immunoprecipitation approaches were used to determine the mechanism by which the lncRNA TPTEP1 affects OC progression. Animal experiments were used to determine the role of the lncRNA TPTEP1 in ovarian tumorigenicity invivo. The expression of the lncRNA TPTEP1 in OC tissues was significantly lower than that in normal tissues and low expression of the lncRNA TPTEP1 was significantly correlated with advanced FIGO stage and the presence of malignant ascites in OC patients. Invitro and invivo, regulation of the expression of the lncRNA TPTEP1 caused changes in OC cell proliferation, migration, invasion and apoptosis. Mechanistically, we found that TPTEP1 directly binds to the polypyrimidine tract-binding protein 1 (PTBP1) protein and inhibits PI3K/AKT signalling. The lncRNA TPTEP1 inhibits PI3K/AKT signalling by directly binding PTBP1, possibly indicating the molecular mechanism underlying its biological function. With further research, these findings may aid in the development of clinically useful strategies for the treatment of OC.

HDAC7 promotes ovarian cancer malignancy via AKT/mTOR signalling pathway.

Ovarian cancer is of the most lethal malignancy and causes serious threat to women health worldwide. A deep understanding of molecular mechanisms underlying ovarian cancer progression is critical for the development of promising therapeutic strategies. In this study, we aimed to employ immunohistochemistry to determine the protein level of HDAC7 in patient tissues, our data showed HDAC7 levels are upregulated in tumour tissues. In addition, we also performed Kaplan-Meier survival analysis to investigate the association between HDAC7 expression and clinical prognosis, and found that HDAC7 expression was associated with poor prognosis in ovarian cancer patients. Inhibition of HDAC7 cells resulted in lower cell proliferation, invasion and colony formation. Furthermore, we also found that HDAC7 inhibition suppressed PI3K/AKT/mTOR pathway. In contrast, exogenous HDAC7 expression activated the PI3K/AKT/mTOR pathway in HDAC7 knockout cells and rescued the cell proliferation, invasion and colony formation. However, inhibition of p-AKT induced lower cell proliferation, metastasis and colony formation abilities. In murine model, HDAC7 KO significantly decreased the tumour burden. These data indicate that HDAC7 is involved in regulation of PI3K/AKT/mTOR pathway and targeting of HDAC7 could be potential therapeutic strategy in the treatment of ovarian cancer.

PDK1 promotes epithelial ovarian cancer progression by upregulating BGN

PDK1 promotes epithelial ovarian cancer progression by upregulating BGN

Actin-related protein 2/3 complex subunit 1B promotes ovarian cancer progression by regulating the AKT/PI3K/mTOR signaling pathway.

Actin-related protein 2/3 complex subunit 1B (ARPC1B) is an essential subunit of the actin-related protein 2/3 (Arp2/3) complex. While there have been numerous research reports on Arp2/3 in relation to tumors, there needs to be more research on ARPC1B and its role in tumors, particularly at the pan-cancer level. Utilizing data from the cancer genome atlas (TCGA) and genotype-tissue expression (GTEx) databases, we analyzed ARPC1B expression differences in normal, tumor, and adjacent tissues, investigating its correlation with prognosis and clinical stages in various cancers. We conducted gene enrichment analysis and explored ARPC1B's connection to the tumor immune microenvironment and its impact on anti-tumor drug resistance. In addition, in vivo and in vitro experiments have also been carried out to find the mechanism of ARPC1B on ovarian cancer (OV) proliferation and invasion. ARPC1B was highly expressed in 33 tumor types, suggesting its role as a tumor-promoting factor. Its expression correlated with poor prognosis and served as a clinical staging marker in over 10 tumor types. ARPC1B is implicated in various biological processes and signaling pathways, uniquely associated with tumor immunity, indicating immunosuppressive conditions in high-expression cases. High ARPC1B expression was linked to resistance to six anti-tumor drugs. Further experiments showed that ARPC1B can affect the proliferation, apoptosis, migration, and invasion of OV cells through the AKT/PI3K/mTOR pathway. ARPC1B is a biomarker for immune suppression, prognosis, clinical staging, and drug resistance, providing new insights for cancer therapeutics.

Exploring Molecular Drivers of PARPi Resistance in BRCA1-Deficient Ovarian Cancer: The Role of LY6E and Immunomodulation.

Approximately 50% of patients diagnosed with ovarian cancer harbor tumors with mutations in BRCA1, BRCA2, or other genes involved in homologous recombination repair (HR). The presence of homologous recombination deficiency (HRD) is an approved biomarker for poly-ADP-ribose polymerase inhibitors (PARPis) as a maintenance treatment following a positive response to initial platinum-based chemotherapy. Despite this treatment option, the development of resistance to PARPis is common among recurrent disease patients, leading to a poor prognosis. In this study, we conducted a comprehensive analysis using publicly available datasets to elucidate the molecular mechanisms driving PARPi resistance in BRCA1-deficient ovarian cancer. Our findings reveal a central role for the interferon (IFN) pathway in mediating resistance in the context of BRCA1 deficiency. Through integrative bioinformatics approaches, we identified LY6E, an interferon-stimulated gene, as a key mediator of PARPi resistance, with its expression linked to an immunosuppressive tumor microenvironment (TME) encouraging tumor progression and invasion. LY6E amplification correlates with poor prognosis and increased expression of immune-related gene signatures, which is predictive of immunotherapy response. Interestingly, LY6E expression upon PARPi treatment resistance was found to be dependent on BRCA1 status. Gene expression analysis in the Orien/cBioPortal database revealed an association between LY6E and genes involved in DNA repair, such as Rad21 and PUF60, emphasizing the interplay between DNA repair pathways and immune modulation. Moreover, PUF60, Rad21, and LY6E are located on chromosome 8q24, a locus often amplified and associated with the progression of ovarian cancer. Overall, our study provides novel insights into the molecular determinants of PARPi resistance and highlights LY6E as a promising prognostic biomarker in the management of HRD ovarian cancer. Future studies are needed to fully elucidate the molecular mechanisms underlying the role of LY6E in PARPi resistance.

Egfl6 promotes ovarian cancer progression by enhancing the immunosuppressive functions of tumor-associated myeloid cells.

Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) play a critical role in resistance to immunotherapy. In this study, we identified epidermal growth factor-like 6 (Egfl6) as a new regulator of myeloid cell functions. Our analyses indicated that Egfl6, via binding with β3 integrins and activation of p38 and SYK signaling, acts as a chemotactic factor for myeloid cells migration and promotes their differentiation towards an immunosuppressive state. In syngeneic mouse models of ovarian cancer (OvCa), tumor expression of Egfl6 increased the intra-tumoral accumulation of polymorphonuclear (PMN) MDSCs and TAMs and their expression of immunosuppressive factors, including CXCL2, IL-10 and PD-L1. Consistent with this, in an immune 'hot' tumor model, Egfl6 expression eliminated response to a-PD-L1 therapy, while Egfl6 neutralizing antibody decreased the accumulation of tumor-infiltrating CD206+ TAMs and PMN-MDSCs and restored the efficacy of a-PD-L1 therapy. Supporting a role in human tumors, in human OvCa tissue samples, areas of high EGFL6 expression co-localized with myeloid cell infiltration. scRNAseq analyses revealed a correlation between EGFL6 and immune cell expression of immunosuppressive factors. Our data provide mechanistic insights into the onco-immunologic functions of EGFL6 in mediating tumor immune suppression and identified EGFL6 as a potential novel therapeutic target to enhance immunotherapy in OvCa patients.