Bruna Mascaro-Cordeiro1,2, Indhira Dias Oliveira1, Francine Tesser-Gamba1, Lorena Favaro Pavon3, Nasjla Saba-Silva1, Sergio Cavalheiro1,3, Patrícia Dastoli1, Silvia Regina Caminada Toledo4,5. 1. Pediatrics Oncology Institute-GRAACC (Grupo de Apoio ao Adolescente e à Criança com Câncer) /UNIFESP (Federal University of Sao Paulo), Rua Botucatu, 743, Floor 8 - Genetics Laboratory, Vila Clementino, São Paulo, SP, Zip Code 04023-062, Brazil. 2. Department of Morphology and Genetics, Division of Genetics, Federal University of São Paulo, São Paulo, SP, Brazil. 3. Departament of Neurology, Federal University of Sao Paulo, Sao Paulo, SP, Brazil. 4. Pediatrics Oncology Institute-GRAACC (Grupo de Apoio ao Adolescente e à Criança com Câncer) /UNIFESP (Federal University of Sao Paulo), Rua Botucatu, 743, Floor 8 - Genetics Laboratory, Vila Clementino, São Paulo, SP, Zip Code 04023-062, Brazil. silviatoledo@graacc.org.br. 5. Department of Morphology and Genetics, Division of Genetics, Federal University of São Paulo, São Paulo, SP, Brazil. silviatoledo@graacc.org.br.
Abstract
PURPOSE: Histone deacetylate inhibitors (HDACi), as valproic acid (VA), have been reported to enhance efficacy and to prevent drug resistance in some tumors, including medulloblastoma (MB). In the present study, we investigated VA role, combined to cisplatin (CDDP) in cell viability and gene expression of MB cell lines. METHODS: Dose-response curve determined IC50 values for each treatment: (1) VA single, (2) CDDP single, and (3) VA and CDDP combined. Cytotoxicity and flow cytometry evaluated cell viability after exposure to treatments. Quantitative PCR evaluated gene expression levels of AKT, CTNNB1, GLI1, KDM6A, KDM6B, NOTCH2, PTCH1, and TERT, before and after treatment. Besides, we performed next-generation sequencing (NGS) for PTCH1, TERT, and TP53 genes. RESULTS: The most effective treatment to reduce viability was combined for D283MED and ONS-76; and CDDP single for DAOY cells (p < 0.0001). TERT, GLI1, and AKT genes were overexpressed after treatments with VA. D283MED and ONS-76 cells presented variants in TERT and PTCH1, respectively and DAOY cell line presented a TP53 mutation. CONCLUSIONS: MB tumors belonging to SHH molecular subgroup, with TP53MUT, would be the ones that present high risk in relation to VA use during the treatment, while TP53WT MBs can benefit from VA therapy, both SHH and groups 3 and 4. Our study shows a new perspective about VA action in medulloblastoma cells, raising the possibility that VA may act in different patterns. According to the genetic background of MB cell, VA can stimulate cell cycle arrest and apoptosis or induce resistance to treatment via signaling pathways activation.
PURPOSE: Histone deacetylate inhibitors (HDACi), as valproic acid (VA), have been reported to enhance efficacy and to prevent drug resistance in some tumors, including medulloblastoma (MB). In the present study, we investigated VA role, combined to cisplatin (CDDP) in cell viability and gene expression of MB cell lines. METHODS: Dose-response curve determined IC50 values for each treatment: (1) VA single, (2) CDDP single, and (3) VA and CDDP combined. Cytotoxicity and flow cytometry evaluated cell viability after exposure to treatments. Quantitative PCR evaluated gene expression levels of AKT, CTNNB1, GLI1, KDM6A, KDM6B, NOTCH2, PTCH1, and TERT, before and after treatment. Besides, we performed next-generation sequencing (NGS) for PTCH1, TERT, and TP53 genes. RESULTS: The most effective treatment to reduce viability was combined for D283MED and ONS-76; and CDDP single for DAOY cells (p < 0.0001). TERT, GLI1, and AKT genes were overexpressed after treatments with VA. D283MED and ONS-76 cells presented variants in TERT and PTCH1, respectively and DAOY cell line presented a TP53 mutation. CONCLUSIONS:MB tumors belonging to SHH molecular subgroup, with TP53MUT, would be the ones that present high risk in relation to VA use during the treatment, while TP53WT MBs can benefit from VA therapy, both SHH and groups 3 and 4. Our study shows a new perspective about VA action in medulloblastoma cells, raising the possibility that VA may act in different patterns. According to the genetic background of MB cell, VA can stimulate cell cycle arrest and apoptosis or induce resistance to treatment via signaling pathways activation.
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