Amancio Carnero

The Role of Microbiota in Ovarian Cancer: Implications for Treatment Response and Therapeutic Strategies

Cancer remains a global health challenge (18.1 million new cases in 2020), with incidence projected to reach 28 million within two decades. Ovarian cancer (OC) is the deadliest gynecologic malignancy, usually diagnosed at advanced stages and with poorly understood etiology. Emerging evidence implicates reproductive tract and gut microbiota in OC biology. Microbiota shape carcinogenesis via turnover, immunity, and metabolism; dysbiosis promotes DNA damage, inflammation, and carcinogenic metabolites, engaging multiple hallmarks of cancer. In OC, microbes may reach tumors by local ascent, translocation, or hematogenous spread, originating from vagina, upper reproductive tract, peritoneal fluid, or gut. Lactobacillus-dominant vaginal communities support mucosal integrity, whereas anaerobes disrupt barriers, increase inflammation, and correlate with OC risk; mouse models show vaginal dysbiosis accelerates tumor progression. Distinct microbial profiles in upper reproductive sites and peritoneal fluid associated with immune remodeling. Gut dysbiosis drives barrier loss, immune imbalance, and estrogen reactivation. Microbial metabolites (lipopolysaccharides, short-chain fatty acids) modulate oncogenic pathways, altering epithelial–mesenchymal transition, immune evasion, and drug resistance. Across cohorts, OC tissues and fluids show Pseudomonadota/Bacteroidota enrichment and Akkermansia depletion; fecal microbiota from OC patients accelerates tumor growth in mice, whereas Akkermansia supplementation restores antitumor immunity. Antibiotic exposure and platinum resistance associate with reduced diversity and expansion of lactate-producing taxa. Microbiome-informed interventions–diet, probiotics/postbiotics, fecal microbiota transfer, and selective antibiotics–may augment chemotherapy and immunotherapy. Overall, the microbiome is a modifiable determinant of OC risk, progression, and treatment response, warranting rigorous, standardized, multi-omics studies.

Integrative multi-omic analysis reveals a PAX8-driven gene network linking tumor stemness to therapy response in ovarian cancer

Abstract The transcription factor PAX8 is expressed in most ovarian tumors, being associated with increased tumorigenesis. Although recent studies have addressed the gene regulatory functions of PAX8 in ovarian cancer, an integrative analysis of multi-omic and patient data is required to identify the core regulatory network of PAX8 and its prognostic and therapeutic value. Here, we integrate PAX8 chromatin binding and accessibility data in ovarian cancer cells with transcriptomic and patients’ data to gain insight into the core gene regulatory network orchestrated by PAX8 in ovarian tumors. Integration of differential chromatin accessibility, transcription factor binding, and gene expression upon PAX8 knockout provides a core regulatory network that explains most of the genes regulated by PAX8. We combine these target genes with patient expression data and find a PAX8 gene signature associated with tumor stemness, a property related to therapy resistance. Indeed, we show that the PAX8 gene signature predicts disease outcome and response to therapy in ovarian cancer patients. Finally, we validated experimentally our results from bioinformatic analyses, thus reassuring their robustness. Our findings uncover a PAX8 core network that represents a promising strategy for targeted antitumor therapies and open new pathways to fight against ovarian cancer resistance.

Protein homeostasis maintained by HOOK1 levels promotes the tumorigenic and stemness properties of ovarian cancer cells through reticulum stress and autophagy

Abstract Background Ovarian cancer has a high mortality rate mainly due to its resistance to currently used therapies. This resistance has been associated with the presence of cancer stem cells (CSCs), interactions with the microenvironment, and intratumoral heterogeneity. Therefore, the search for new therapeutic targets, particularly those targeting CSCs, is important for improving patient prognosis. HOOK1 has been found to be transcriptionally altered in a substantial percentage of ovarian tumors, but its role in tumor initiation and development is still not fully understood. Methods The downregulation of HOOK1 was performed in ovarian cancer cell lines using CRISPR/Cas9 technology, followed by growth in vitro and in vivo assays. Subsequently, migration (Boyden chamber), cell death (Western-Blot and flow cytometry) and stemness properties (clonal heterogeneity analysis, tumorspheres assay and flow cytometry) of the downregulated cell lines were analysed. To gain insights into the specific mechanisms of action of HOOK1 in ovarian cancer, a proteomic analysis was performed, followed by Western-blot and cytotoxicity assays to confirm the results found within the mass spectrometry. Immunofluorescence staining, Western-blotting and flow cytometry were also employed to finish uncovering the role of HOOK1 in ovarian cancer. Results In this study, we observed that reducing the levels of HOOK1 in ovarian cancer cells reduced in vitro growth and migration and prevented tumor formation in vivo. Furthermore, HOOK1 reduction led to a decrease in stem-like capabilities in these cells, which, however, did not seem related to the expression of genes traditionally associated with this phenotype. A proteome study, along with other analysis, showed that the downregulation of HOOK1 also induced an increase in endoplasmic reticulum stress levels in these cells. Finally, the decrease in stem-like properties observed in cells with downregulated HOOK1 could be explained by an increase in cell death in the CSC population within the culture due to endoplasmic reticulum stress by the unfolded protein response. Conclusion HOOK1 contributes to maintaining the tumorigenic and stemness properties of ovarian cancer cells by preserving protein homeostasis and could be considered an alternative therapeutic target, especially in combination with inducers of endoplasmic reticulum or proteotoxic stress such as proteasome inhibitors.

Targeting Cancer Stem Cells to Overcome Therapy Resistance in Ovarian Cancer

Ovarian cancer is the most lethal gynecological malignancy due to its late detection and high recurrence rate. Resistance to conventional platinum-based therapies and metastasis are attributed to a population of cells within tumors called cancer stem cells, which possess stem-like features and are able to recapitulate new tumors. Recent studies have deepened the understanding of the biology of ovarian cancer stem cells and their special properties and have identified multiple markers and signaling pathways responsible for their self-renewal abilities. Targeting cancer stem cells represents the most promising strategy for overcoming therapy resistance and reducing mortality in ovarian cancer, but further efforts must be made to improve our understanding of the mechanisms involved in therapy resistance. In this review, we summarize our current knowledge about ovarian cancer stem cells, their involvement in metastasis and their interactions with the tumor microenvironment; we also discuss the therapeutic approaches that are being developed to target them to prevent tumor relapse.

Downregulation of MYPT1 increases tumor resistance in ovarian cancer by targeting the Hippo pathway and increasing the stemness

Abstract Background Ovarian cancer is one of the most common and malignant cancers, partly due to its late diagnosis and high recurrence. Chemotherapy resistance has been linked to poor prognosis and is believed to be linked to the cancer stem cell (CSC) pool. Therefore, elucidating the molecular mechanisms mediating therapy resistance is essential to finding new targets for therapy-resistant tumors. Methods shRNA depletion of MYPT1 in ovarian cancer cell lines, miRNA overexpression, RT-qPCR analysis, patient tumor samples, cell line- and tumorsphere-derived xenografts, in vitro and in vivo treatments, analysis of data from ovarian tumors in public transcriptomic patient databases and in-house patient cohorts. Results We show that MYPT1 (PPP1R12A), encoding myosin phosphatase target subunit 1, is downregulated in ovarian tumors, leading to reduced survival and increased tumorigenesis, as well as resistance to platinum-based therapy. Similarly, overexpression of miR-30b targeting MYPT1 results in enhanced CSC-like properties in ovarian tumor cells and is connected to the activation of the Hippo pathway. Inhibition of the Hippo pathway transcriptional co-activator YAP suppresses the resistance to platinum-based therapy induced by either low MYPT1 expression or miR-30b overexpression, both in vitro and in vivo. Conclusions Our work provides a functional link between the resistance to chemotherapy in ovarian tumors and the increase in the CSC pool that results from the activation of the Hippo pathway target genes upon MYPT1 downregulation. Combination therapy with cisplatin and YAP inhibitors suppresses MYPT1-induced resistance, demonstrating the possibility of using this treatment in patients with low MYPT1 expression, who are likely to be resistant to platinum-based therapy.