Reversing platinum resistance in ovarian cancer multicellular spheroids by targeting Bcl-2

Ya'nan Yang; Song Li; Yiting Sun; Di Zhang; Zeyi Zhao; Lian Liu

doi:10.2147/OTT.S187015

Reversing platinum resistance in ovarian cancer multicellular spheroids by targeting Bcl-2

Onco Targets Ther. 2019 Jan 29:12:897-906. doi: 10.2147/OTT.S187015. eCollection 2019.

Authors

Ya'nan Yang^{1

2

3}, Song Li¹, Yiting Sun¹, Di Zhang¹, Zeyi Zhao¹, Lian Liu¹

Affiliations

¹ Department of Chemotherapy, Cancer Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China, lianliusub@163.com.
² Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China.
³ Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.

Abstract

Purpose: Peritoneal metastasis is the most common pathway for the spread of ovarian cancer. Ovarian cancer cells in ascites prefer to aggregate into the more chemoresistant multicellular spheroids (MCSs), leading to treatment failure and disease recurrence. We previously established a suspension MCS model of ovarian cancer cells in vitro and found that the MCS cells acquired drug resistance to cisplatin. In the present study, we aimed to uncover the underlying mechanism of the platinum resistance of MCS and the potential targets to reverse the drug resistance.

Materials and methods: MCS models were established for the phenotypic studies, including proliferation, invasion, migration, drug resistance, apoptosis assays, and signaling pathway analysis. The key molecule, Bcl-2, was screened by profile analysis and validated by Western blotting. siRNA was used to verify the anti-cisplatin-induced apoptosis effect of Bcl-2. The Bcl-2 inhibitor, ABT-737, was used for improving the sensitivity of MCS to cisplatin. The 50% inhibitory concentrations (IC50) were measured by viability assays treated with different concentrations of cisplatin. Flow cytometry and Western blotting were used for quantification of drug-induced apoptosis.

Results: The ovarian cancer MCS showed a proliferation-stagnant but invasive phenotype when resuspended. When treated with cisplatin, MCS cells showed much higher viability, with significantly fewer apoptotic cells than the adherent cells. Levels of Bcl-2 were upregulated in ovarian cancer ascitic cells and MCS cells. Bcl-2 knockdown by siRNA or blockage by ABT-737 enhanced the cisplatin-induced apoptosis and reduced the 50% inhibitory concentrations of cisplatin for MCS by 58.5% and 88.2%, respectively.

Conclusion: The upregulated Bcl-2 contributes to cisplatin resistance in our MCS model and targeting it sensitizes the MCS to cisplatin treatment. This provides us a preliminary treatment method for ovarian cancer peritoneal metastasis.

Keywords: Bcl-2; drug resistance; molecular targeted therapy; multicellular spheroids; ovarian neoplasms.