Novel Thiosemicarbazones Sensitize Pediatric Solid Tumor Cell-Types to Conventional Chemotherapeutics through Multiple Molecular Mechanisms

Silvia Paukovcekova; Jan Skoda; Jakub Neradil; Erika Mikulenkova; Petr Chlapek; Jaroslav Sterba; Des R Richardson; Renata Veselska

doi:10.3390/cancers12123781

Novel Thiosemicarbazones Sensitize Pediatric Solid Tumor Cell-Types to Conventional Chemotherapeutics through Multiple Molecular Mechanisms

Cancers (Basel). 2020 Dec 15;12(12):3781. doi: 10.3390/cancers12123781.

Authors

Silvia Paukovcekova¹, Jan Skoda^{1

2}, Jakub Neradil^{1

2}, Erika Mikulenkova^{1

2}, Petr Chlapek^{1

2}, Jaroslav Sterba^{2

3}, Des R Richardson^{1

4}, Renata Veselska^{1

2

3}

Affiliations

¹ Department of Experimental Biology, Faculty of Science, Masaryk University, 61137 Brno, Czech Republic.
² International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic.
³ Department of Pediatric Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, 66263 Brno, Czech Republic.
⁴ Griffith Institute for Drug Discovery, Centre for Cancer Cell Biology and Drug Discovery, Griffith University, Brisbane, Queensland 4111, Australia.

Abstract

Combining low-dose chemotherapies is a strategy for designing less toxic and more potent childhood cancer treatments. We examined the effects of combining the novel thiosemicarbazones, di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), or its analog, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), with the standard chemotherapies, celecoxib (CX), etoposide (ETO), or temozolomide (TMZ). These combinations were analyzed for synergism to inhibit proliferation of three pediatric tumor cell-types, namely osteosarcoma (Saos-2), medulloblastoma (Daoy) and neuroblastoma (SH-SY5Y). In terms of mechanistic dissection, this study discovered novel thiosemicarbazone targets not previously identified and which are important for considering possible drug combinations. In this case, DpC and Dp44mT caused: (1) up-regulation of a major protein target of CX, namely cyclooxygenase-2 (COX-2); (2) down-regulation of the DNA repair protein, O⁶-methylguanine DNA methyltransferase (MGMT), which is known to affect TMZ resistance; (3) down-regulation of mismatch repair (MMR) proteins, MSH2 and MSH6, in Daoy and SH-SY5Y cells; and (4) down-regulation in all three cell-types of the MMR repair protein, MLH1, and also topoisomerase 2α (Topo2α), the latter of which is an ETO target. While thiosemicarbazones up-regulate the metastasis suppressor, NDRG1, in adult cancers, it is demonstrated herein for the first time that they induce NDRG1 in all three pediatric tumor cell-types, validating its role as a potential target. In fact, siRNA studies indicated that NDRG1 was responsible for MGMT down-regulation that may prevent TMZ resistance. Examining the effects of combining thiosemicarbazones with CX, ETO, or TMZ, the most promising synergism was obtained using CX. Of interest, a positive relationship was observed between NDRG1 expression of the cell-type and the synergistic activity observed in the combination of thiosemicarbazones and CX. These studies identify novel thiosemicarbazone targets relevant to childhood cancer combination chemotherapy.

Keywords: Dp44mT; DpC; celecoxib; combined anti-cancer treatment; etoposide; medulloblastoma; neuroblastoma; osteosarcoma; temozolomide; thiosemicarbazones.

Grants and funding

17-33104A/Ministerstvo Zdravotnictví Ceské Republiky