Suppression of heat shock protein 70 by siRNA enhances the antitumor effects of cisplatin in cultured human osteosarcoma cells

Abstract

Although advances in chemotherapy have improved the prognosis for osteosarcoma, some patients do not respond sufficiently to treatment. Heat shock protein 70 (Hsp70) is expressed at high levels in cancer cells and attenuates the therapeutic efficacy of anticancer agents, resulting in a poorer prognosis. This study investigated whether small interfering RNA (siRNA)-mediated inhibition of Hsp70 expression in an osteosarcoma cell line would enhance sensitivity to cisplatin. The expression of Hsp70 with cisplatin treatment was observed by using Western blotting and real-time reverse transcription polymerase chain reaction (RT-PCR). Changes in the IC 50 of cisplatin when Hsp70 was inhibited by siRNA were evaluated. Cisplatin's effectiveness in inducing apoptosis was assessed by assay of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), caspase-3 activity, and mitochondrial membrane potential. Up-regulation of Hsp70 expression was dependent on the concentration of cisplatin. Inhibition of Hsp70 expression significantly reduced the IC 50 of cisplatin. When cisplatin was added to osteosarcoma cells with Hsp70 expression inhibited, a significant increase in apoptosis was demonstrated in TUNEL, caspase-3, and mitochondrial membrane potential assays. Inhibition of Hsp70 expression induced apoptosis in cultured osteosarcoma cells, indicating that Hsp70 inhibition enhanced sensitivity to cisplatin. Inhibition of Hsp70 expression may provide a new adjuvant therapy for osteosarcoma.

Inducible HSP70 antagonizes cisplatin‑induced cell apoptosis through inhibition of the MAPK signaling pathway in HGC‑27 cells

“…1 – 3 , HSP70 overexpression decreased cisplatin-induced HGC-27 cell apoptosis, while inhibition of HSP70 using a specific inhibitor or by transfection of specific shRNA enhanced the cellular apoptosis induced by cisplatin. The present results are consistent with the study of Mori et al ( 14 ). In addition, Liu et al ( 2 ) reported that an HSP70 inhibitor combined with cisplatin suppresses cervical cancer cell proliferation and transplanted tumor growth.…”

“…As a member of this family, HSP70 has been reported to be highly expressed in different types of cancer ( 6 ) and is considered to be a negative prognostic factor in breast cancer, osteosarcoma and bladder cancer. By contrast, it has been reported as a positive prognostic factor in esophageal, pancreatic and renal cancers ( 14 - 16 ). Recently, multiple studies have demonstrated that HSP70 is involved in resistance to anticancer agents in tumors ( 14 , 17 , 18 ); however, the molecular mechanism of its action in resistance to chemotherapy remains unclear.…”

“…Other studies have also demonstrated that HSP70 regulates tumor cell apoptosis by inhibiting the activation of JNK and NF-κB signaling ( 20 , 21 ). Cisplatin, a commonly used chemotherapeutic drug, is used clinically to treat cancer, and HSP70 expression decreases the sensitivity of osteosarcoma cells to cisplatin ( 14 ). However, the question of whether HSP70 regulates the sensitivity of gastric cancer cells to cisplatin and its underlying molecular mechanism still remain to be explored.…”

Blockade of HSP70 by VER-155008 synergistically enhances bortezomib-induced cytotoxicity in multiple myeloma

“…HSPs are chaperone proteins induced by a variety of different stresses. As a member of this family, HSP70 is highly expressed in a variety of cancers and correlated with tumor grade, metastasis, poor prognosis, and chemo-resistance (Behnsawy et al 2013;Daugaard et al 2007;Kumar et al 2016;Mori et al 2017;Yang et al 2012;Yoshidomi et al 2014). In the current study, we found that HSP70 was one of the most important HSPs induced by bortezomib and demonstrated that targeting HSP70 in combination with bortezomib could synergistically induce cytotoxicity, therefore improving the efficacy of MM treatment.…”

Molecular Chaperones in Osteosarcoma: Diagnosis and Therapeutic Issues

“…JUN, in turn, is able to bind the promoter region of miR-223, promoting its transcription. HSP70 thus participates in the CIS resistance mechanism in OS cells [ 121 , 122 ].…”