USP1 links platinum resistance to cancer cell dissemination by regulating Snail stability

Abstract

Resistance to platinum-based chemotherapy is a common event in patients with cancer, generally associated with tumor dissemination and metastasis. Whether platinum treatment per se activates molecular pathways linked to tumor spreading is not known. Here, we report that the ubiquitin-specific protease 1 (USP1) mediates ovarian cancer cell resistance to platinum, by regulating the stability of Snail, which, in turn, promotes tumor dissemination. At the molecular level, we observed that upon platinum treatment, USP1 is phosphorylated by ATM and ATR and binds to Snail. Then, USP1 de-ubiquitinates and stabilizes Snail expression, conferring resistance to platinum, increased stem cell–like features, and metastatic ability. Consistently, knockout or pharmacological inhibition of USP1 increased platinum sensitivity and decreased metastatic dissemination in a Snail-dependent manner. Our findings identify Snail as a USP1 target and open the way to a novel strategy to overcome platinum resistance and more successfully treat patients with ovarian cancer.

TIMP-1 Is Overexpressed and Secreted by Platinum Resistant Epithelial Ovarian Cancer Cells

“…Interestingly, in MCF-7 breast cancer cell overexpression of TIMP-1 increases the expression and phosphorylation of proteins involved in the DNA damage response and confers resistance to epirubicin or topoisomerase inhibitors but not to cisplatin, suggesting that it could impact on the response to chemotherapy in a cell-dependent manner [24]. In this regard, it is important to point out that MCF-7 cells are derive from luminal breast cancer and are insensitive to cisplatin [17].…”

“…Dose-response curves were performed essentially as described previously [9,16,17]. Briefly, EOC cells were seeded in 96-well culture plates and treated with increasing doses of cispaltin (TEVA Italia) for 72 h. For treatment with recombinant human TIMP-1 (R&D Systems), TOV-112D and OVSAHO parental cells were treated with increasing doses of CDDP in combination or not with the recombinant protein (100 ng/mL) for 16 h. Cell viability was analyzed 24 h after CDDP removal by MTS assay using the CellTiter 96 AQueous cell proliferation assay kit (Promega)…”

“…Overall, the collected data indicated that TIMP-1 overexpression was associated with the PT-resistant phenotype of the analyzed EOC cells. Since TIMP molecules, by modulating the activity of metalloproteinases, could affect the behavior of tumor cells as well as endothelial cells [17], we initially explored the regulation of TIMP-1 by platinum in parental and PT-resistant EOC cells. qRT-PCR confirmed that TIMP-1 was over-expressed in PT-res cell clones, and we found that its expression was induced by cisplatin (CDDP) both in parental and PT-res cells ( Figure 2B).…”

Identification and Characterization of a New Platinum-Induced TP53 Mutation in MDAH Ovarian Cancer Cells

“…Dose-response curves were performed essentially as previously described [13,14]. Briefly, EOC cells were seeded in 96-well culture plates and treated with increasing doses of cisplatin (CDDP) (TEVA Italia) for 72 h. For dose-response curves of p53-silenced MDAH, cells were seeded in 96-well culture plates and after 24 h transduced with sh-ctrl or sh-p53 lentiviral particles (Mission Sigma TRCN0000003756).…”

“…p53 protein stability was evaluated in MDAH-2774 parental and PT-res clones (#12 and #42) treated with CHX (10 mg/mL) for the indicated time points using procedures as previously described in references [13,14].…”