RESUMO
The tumor-suppressor p53 is commonly inactivated in colorectal cancer and pancreatic ductal adenocarcinoma, but existing treatment options for p53-mutant (p53Mut) cancer are largely ineffective. Here, we report a therapeutic strategy for p53Mut tumors based on abnormalities in the DNA repair response. Investigation of DNA repair upon challenge with thymidine analogs reveals a dysregulation in DNA repair response in p53Mut cells that leads to accumulation of DNA breaks. Thymidine analogs do not interrupt DNA synthesis but induce DNA repair that involves a p53-dependent checkpoint. Inhibitors of poly(ADP-ribose) polymerase (PARPis) markedly enhance DNA double-strand breaks and cell death induced by thymidine analogs in p53Mut cells, whereas p53 wild-type cells respond with p53-dependent inhibition of the cell cycle. Combinations of trifluorothymidine and PARPi agents demonstrate superior anti-neoplastic activity in p53Mut cancer models. These findings support a two-drug combination strategy to improve outcomes for patients with p53Mut cancer.
Assuntos
Neoplasias Colorretais , Neoplasias Pancreáticas , Humanos , Proteína Supressora de Tumor p53/genética , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/uso terapêutico , Reparo do DNA , Poli(ADP-Ribose) Polimerases/genética , Poli(ADP-Ribose) Polimerases/metabolismo , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/genética , DNA/uso terapêutico , Timidina/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genéticaRESUMO
Breast carcinomas commonly carry mutations in the tumor suppressor p53, although therapeutic efforts to target mutant p53 have previously been unfruitful. Here we report a selective combination therapy strategy for treatment of p53 mutant cancers. Genomic data revealed that p53 mutant cancers exhibit high replication activity and express high levels of the Base-Excision Repair (BER) pathway, whereas experimental testing showed substantial dysregulation in BER. This defect rendered accumulation of DNA damage in p53 mutant cells upon treatment with deoxyuridine analogues. Notably, inhibition of poly (ADP-ribose) polymerase (PARP) greatly enhanced this response, whereas normal cells responded with activation of the p53-p21 axis and cell cycle arrest. Inactivation of either p53 or p21/CDKN1A conferred the p53 mutant phenotype. Preclinical animal studies demonstrated a greater anti-neoplastic efficacy of the drug combination (deoxyuridine analogue and PARP inhibitor) than either drug alone. This work illustrates a selective combination therapy strategy for p53 mutant cancers that will improve survival rates and outcomes for thousands of breast cancer patients.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Reparo do DNA/genética , Mutação , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Proteína Supressora de Tumor p53/genética , Ensaios Antitumorais Modelo de Xenoenxerto/métodos , Células A549 , Animais , Linhagem Celular , Linhagem Celular Tumoral , Inibidor de Quinase Dependente de Ciclina p21/genética , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Combinação de Medicamentos , Feminino , Humanos , Camundongos Endogâmicos BALB C , Camundongos SCID , Ftalazinas/administração & dosagem , Piperazinas/administração & dosagem , Inibidores de Poli(ADP-Ribose) Polimerases/administração & dosagem , Pirrolidinas/administração & dosagem , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Timina/administração & dosagem , Trifluridina/administração & dosagem , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
Studies have recently demonstrated that mesenchymal stem cells (MSCs) have therapeutic capabilities on many diseases and this effect is mainly mediated by miRNAs. However, the actual mechanism of MSCs paracrine effect on testis to improve male fertility is still elusive. Herein, we evaluated the altered expression of some spermatogenesis-related miRNAs and their target genes following transplantation of bone marrow (BM)-derived MSCs into testes of busulfan-induced azoospermic rats using real time PCR. Transplantation of MSCs improved fertility of azoospermic rats as revealed by enhanced serum levels of testosterone and estradiol, and upregulated expression of germ cellspecific genes. Azo rats injected with MSCs also exhibited a significant downregulated expression of miRNA-19b, miRNA-100, miRNA-141, miRNA146a, miRNA-429, and let7a and a significant upregulated expression of miRNA-21, miRNA-34b, miRNA-34c, miRNA-122, miRNA-449a, miRNA-449b, and miRNA-449c in the testis as compared to Azo rats injected with phosphate buffer saline. Transplantation of MSCs was also accompanied with restoration of the disrupted expression of Ccnd1, E2F1, Myc, and PLCXD3 (target genes for miRNA-34 and miRNA449 clusters) and ERα and AKT1 (target genes for miRNA-100 and let7a) to level comparable to that of the fertile group. Upon these data, we infer that BM-MSCs can improve fertility of azoospermic rats and this effect was followed by altered expression of some spermatogenesis-related miRNAs and their target genes. These findings provide MSCs as a promising and effective cell-based therapeutic method for azoospermic patients, but further investigations are required before clinical application.