Most women with ovarian cancer (OC) develop resistance to platinum chemotherapy, posing a significant challenge to treatment. Matrix metalloproteinase 3 (MMP3) is overexpressed in High-Grade Serous Ovarian Cancer (HGSOC) and is associated with poor survival outcomes; however, its role in platinum resistance remains underexplored. We evaluated the baseline and cisplatin-induced MMP3 transcript and protein levels in cisplatin-resistant OC cells, revealing significantly higher MMP3 levels in cisplatin-resistant cells than in cisplatin-sensitive cells. siRNA-mediated MMP3 knockdown in cisplatin-resistant OC cells significantly reduced viability, proliferation, and invasion, and these effects were further enhanced when combined with cisplatin treatment, indicating a possible synergistic impact on reducing cancer cell aggressiveness; however, chemical MMP3 inhibition did not replicate these effects. RNA sequencing of MMP3-siRNA-treated cisplatin-resistant HGSOC cells revealed 415 differentially expressed genes (DEGs) compared to the negative control, with an additional 440 DEGs identified in MMP3-siRNA HGSOC cells treated in combination with cisplatin. These DEGs were enriched in pathways related to cell cycle regulation, apoptosis, metabolism, stress response, and extracellular matrix organization. Co-immunoprecipitation-coupled mass spectroscopy (IP-MS) identified MMP3-interacting proteins that may contribute to cell survival and chemoresistance in cisplatin-resistant OC. While MMP3-siRNA monotherapy did not reduce tumor growth in vivo, its combination with cisplatin significantly inhibited tumor growth in a cisplatin-resistant HGSOC xenograft model. These findings underscore the multifaceted role of MMP3 in cisplatin resistance, suggesting its involvement in critical cellular processes driving chemoresistance and highlighting the challenges associated with direct MMP3 targeting in therapeutic strategies.

Metastasis and drug resistance are major contributors to cancer-related fatalities worldwide. In ovarian cancer (OC), a staggering 70% develop resistance to the front-line therapy, cisplatin. Despite proposed mechanisms, the molecular events driving cisplatin resistance remain unclear. Dysregulated microRNAs (miRNAs) play a role in OC initiation, progression, and chemoresistance, yet few studies have compared miRNA expression in OC samples and cell lines. This study aimed to identify key miRNAs involved in the cisplatin resistance of high-grade-serous-ovarian-cancer (HGSOC), the most common gynecological malignancy. MiRNA expression profiles were conducted on RNA isolated from formalin-fixed-paraffin-embedded human ovarian tumor samples and HGSOC cell lines. Nine miRNAs were identified in both sample types. Targeting these with oligonucleotide miRNA inhibitors (OMIs) reduced proliferation by more than 50% for miR-203a, miR-96-5p, miR-10a-5p, miR-141-3p, miR-200c-3p, miR-182-5p, miR-183-5p, and miR-1206. OMIs significantly reduced migration for miR-183-5p, miR-203a, miR-296-5p, and miR-1206. Molecular pathway analysis revealed that the nine miRNAs regulate pathways associated with proliferation, invasion, and chemoresistance through PTEN, ZEB1, FOXO1, and SNAI2. High expression of miR-1206, miR-10a-5p, miR-141-3p, and miR-96-5p correlated with poor prognosis in OC patients according to the KM plotter database. These nine miRNAs could be used as targets for therapy and as markers of cisplatin response.

Background: Inflammatory breast cancer (IBC) is a rare and aggressive subtype of breast cancer that accounts for 1–5% of BC patients and regularly affects women under 40 years of age. Approximately 50% of IBC cases are HER2+ and can be treated with the monoclonal antibody-based therapy Herceptin (trastuzumab). However, resistance to Herceptin develops within a year, and effective second-line targeted therapies are currently unavailable for IBC patients. Lipocalin-2 (LCN2) is a promising therapeutic target for IBC due to its role in promoting tumor invasiveness, angiogenesis, and the inflammatory tumor microenvironment characteristic of IBC. Objective: We developed Herceptin-conjugated liposomes loaded with LCN2-targeted small-interference RNA (siRNA) for HER2+ IBCs. Methods: We synthesized DSPE-PEG(2000)-maleimide-Herceptin in a three-step process and formulated the liposomes together with DOPC, PEG(2000)-PE, cholesterol, and siRNA. Results: Dynamic light scattering confirmed the liposome size distribution, which was 66.7 nm for the Herceptin-conjugated liposome versus 43.0 nm in a non-functionalized liposome. Here, we report efficient internalization of this formulation into HER2+ IBC cells, reducing LCN2 levels by 30% and disrupting tumor emboli formation. RNA sequencing revealed 139 genes that were differentially expressed upon LCN2 knockdown, with 25 canonical pathways identified through Ingenuity Pathway Analysis. Conclusions: These findings suggest that LCN2-targeted siRNA within Herceptin-targeted liposomes represents a promising therapeutic strategy for IBC.