Homologous recombination (HR) is traditionally portrayed as a DNA double-strand break repair pathway. However, emerging evidence positions RAD51, its partners BRCA1, BRCA2, and other HR factors at the core of a broader genome-maintenance network that operates by a “prevent and protect” strategy extending beyond repair. Here, we review how RAD51 can shield DNA from nucleolytic processing mediated by MRE11 and related nucleases, promote fork reversal, suppress replicative DNA gaps accumulation, and bind abasic sites, averting their conversion into cytotoxic intermediates. These extended functions counteract endogenous replication stress as shown in BRCA1- or BRCA2-deficient contexts, where failure to prevent gaps, protect forks, and safeguard abasic DNA accelerates genomic instability. The functional impairment of HR proteins, which interface with base-excision repair and translesion synthesis, rewires these pathways, driving distinctive base-substitution mutational signatures of HR-defective tumors. Abasic sites, especially from methyl-cytosine metabolism, put replication forks at risk of breaking, amplifying the need for RAD51-mediated defense. Such redefinition of homologous recombination protein function as part of an anticipatory surveillance and protective system, rather than a repair-only module, bears important implications for understanding tumorigenesis, therapy resistance, and aging.

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6iss) are widely used in first-line metastatic breast cancer. For patients with progression under CDK4/6is, there is currently no standard treatment recommended at the category 1 level in international guidelines. The purpose of this article is to review the cellular mechanisms underlying the resistance to CDK4/6is, as well as treatment strategies and the clinical data about the efficacy of subsequent treatments after CDK4/6is-based therapy. In the first part, this review mainly discusses cell-cycle-specific and cell-cycle-non-specific resistance to CDK4/6is, with a focus on early and late progression. In the second part, this review analyzes potential therapeutic approaches and the available clinical data on them: switching to other CDK4/6is, to another single hormonal therapy, to other target therapies (PI3K, mTOR and AKT) and to chemotherapy.

The lack of effective screening and successful treatment contributes to high ovarian cancer mortality, making it the second most common cause of gynecologic cancer death. Development of chemoresistance in up to 75% of patients is the cause of a poor treatment response and reduced survival. Therefore, identifying potential and effective biomarkers for its diagnosis and prognosis is a strong critical need. Copy number alterations are frequent in cancer, and relevant for molecular tumor stratification and patients’ prognoses. In this study, array-CGH analysis was performed in three cell lines and derived cancer stem cells (CSCs) to identify genes potentially predictive for ovarian cancer patients’ prognoses. Bioinformatic analyses of genes involved in copy number gains revealed that AhRR and PPP1R3C expression negatively correlated with ovarian cancer patients’ overall and progression-free survival. These results, together with a significant association between AhRR and PPP1R3C expression and ovarian cancer stemness markers, suggested their potential role in CSCs. Furthermore, AhRR and PPP1R3C’s increased expression was maintained in some CSC subpopulations, reinforcing their potential role in ovarian cancer. In conclusion, we reported for the first time, to the best of our knowledge, a prognostic role of AhRR and PPP1R3C expression in serous ovarian cancer.

Background: High dissemination potential and resistance to standard therapy significantly contribute to high mortality associated with ovarian cancer. Cancer stem cells (CSCs) drive tumor progression, metastasis, and recurrence after treatments’ failure. Here, we provide the first evidence of TIMP1 overexpression in ovarian CSCs, suggesting its potential role as a prognostic biomarker. Methods: Different ovarian cancer cell models were used to explore the potential link between TIMP1 and stem-like phenotypes. Experiments included spheroid formation, drug treatments, gene expression, functional assays, and zebrafish xenograft models to assess cell behavior and molecular changes. Results: TIMP1 was overexpressed in CSCs, and its expression was also upregulated in chemoresistant and anoikis-resistant cells. Our database analysis revealed a correlation between TIMP1 expression levels and poor patient prognosis. Overexpression of TIMP1 in ovarian cancer cell lines was able to recapitulate several features of the ovarian cancer stem cell phenotype, including treatment resistance, expression of stem cell markers, and anoikis resistance. TIMP1-overexpressing cells also exhibited enhanced migration potential in vitro and increased metastatic potential in vivo. Moreover, TIMP1 overexpression significantly altered the transcriptome landscape of cells, highlighting its role in modulating critical pathways associated with cell migration and inflammation. Conclusions: This study identifies the pivotal role of TIMP1 in ovarian CSCs and its contribution to therapy resistance, recurrence, and metastasis.

Background/Objectives: Aneuploidy is a prevalent cancer feature that occurs in many solid tumors. For example, high-grade serous ovarian cancer shows a high level of copy number alterations and genomic rearrangements. This makes genomic variants appealing as diagnostic or prognostic biomarkers, as well as for their easy detection. In this study, we focused on copy number (CN) losses shared by ovarian cancer stem cells (CSCs) to identify chromosomal regions that may be important for CSC features and, in turn, for patients’ prognosis. Methods: Array-CGH and bioinformatic analyses on three CSCs subpopulations were performed. Results: Pathway and gene ontology analyses on genes involved in copy number loss in all CSCs revealed a significant decrease in mRNA surveillance pathway, as well as miRNA-mediated gene silencing. Then, starting from these CN losses, we validated their potential prognostic relevance by analyzing the TCGA cohort. Notably, losses of 4q34.3-q35.2, 8p21.2-p21.1, and 18q12.2-q23 were linked to increased genomic instability. Loss of 18q12.2-q23 was also related to a higher tumor stage and poor prognosis. Finally, specific genes mapping in these regions, such as PPP2R2A and TPGS2A, emerged as potential biomarkers. Conclusions: Our findings highlight the importance of genomic alterations in ovarian cancer and their impact on tumor progression and patients’ prognosis, offering advance in understanding of the application of numerical aberrations as prognostic ovarian cancer biomarkers.