Upregulation of MMP3 promotes cisplatin resistance in ovarian cancer

Seventy percent of women with ovarian cancer develop resistance to cisplatin, contributing to persistently high mortality rates. Understanding the mechanisms behind this resistance is crucial for developing improved therapies. Matrix metalloproteinase 3 (MMP3) is elevated in ovarian cancer patients, but its role in cisplatin resistance remains underexplored. We observed significantly higher MMP3 protein and mRNA levels in cisplatin-resistant high-grade serous ovarian cancer (HGSOC) cells compared to cisplatin-sensitive cells, with further increases following cisplatin treatment. Kaplan‒Meier analysis indicated that patients with lower MMP3 levels have better survival outcomes. MMP3 knockdown via siRNA reduced cell viability, proliferation, and invasion, effects enhanced by cisplatin; however, a chemical MMP3 inhibitor did not replicate these effects. To better understand MMP3’s role, we conducted RNA sequencing to analyze gene expression changes and used immunoprecipitation with mass spectrometry to identify MMP3-interacting proteins, making this the first study to explore this in cisplatin-resistant ovarian cancer. Surprisingly, multiple injections of liposomal MMP3-siRNA increased tumor size in a mouse model, while combining MMP3-siRNA with cisplatin reduced tumor growth. These findings highlight MMP3’s complex role in cisplatin resistance and raise concerns about its targeting in vivo.