RESUMO
Cancer stem cells (CSCs) are linked to metastasis. Moreover, a discrete group of miRNAs (metastamiRs) has been shown to promote metastasis. Accordingly, we propose that miRNAs that function as metastatic promoters may influence the CSC phenotype. To study this issue, we compared the expression of 353 miRNAs in CSCs enriched from breast cancer cell lines using qRT-PCR analysis. One of the most altered miRNAs was miR-10b, which is a reported promoter of metastasis and migration. Stable overexpression of miR-10b in MCF-7 cells (miR-10b-OE cells) promoted higher self-renewal and expression of stemness and epithelial-mesenchymal transition (EMT) markers. In agreement with these results, inhibiting miR-10b expression using synthetic antisense RNAs resulted in a decrease in CSCs self-renewal. Bioinformatics analyses identified several potential miR-10b mRNA targets, including phosphatase and tensin homolog (PTEN), a key regulator of the PI3K/AKT pathway involved in metastasis, cell survival, and self-renewal. The targeting of PTEN by miR-10b was confirmed using a luciferase reporter, qRT-PCR, and Western blot analyses. Lower PTEN levels were observed in CSCs, and miR-10b depletion not only increased PTEN mRNA and protein expression but also decreased the activity of AKT, a downstream PTEN target kinase. Correspondingly, PTEN knockdown increased stem cell markers, whereas AKT inhibitors compromised the self-renewal ability of CSCs and breast cancer cell lines overexpressing miR-10b. In conclusion, miR-10b regulates the self-renewal of the breast CSC phenotype by inhibiting PTEN and maintaining AKT pathway activation.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Autorrenovação Celular/genética , MicroRNAs/genética , Células-Tronco Neoplásicas/metabolismo , PTEN Fosfo-Hidrolase/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Linhagem Celular Tumoral , Movimento Celular/genética , Modelos Animais de Doenças , Transição Epitelial-Mesenquimal/genética , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Xenoenxertos , Humanos , Camundongos , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , RNA Mensageiro/genética , Transdução de Sinais , TranscriptomaRESUMO
We used both in vitro cultures of neuroblastoma cell lines and nude-mice xenotransplants to explore the effects of co-administration of cisplatin and probenecid. Probenecid sensitized neuroblastoma cells, including tumor cells with stem features, to the effects of cisplatin, both in vitro and in vivo. This effect was mediated by an increase in the apoptotic cell death and a concomitant decrease in cell proliferation. This effect is accompanied by modulation of the mRNA and protein of the drug efflux transporters MDR1, MRP2, and BCRP. The co-administration of probenecid with cisplatin should be explored as a possible therapeutic strategy.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Neuroblastoma/tratamento farmacológico , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Apoptose , Caspase 3/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cisplatino/administração & dosagem , Resistencia a Medicamentos Antineoplásicos , Sinergismo Farmacológico , Transição Epitelial-Mesenquimal , Feminino , Expressão Gênica , Humanos , Camundongos Nus , Proteína 2 Associada à Farmacorresistência Múltipla , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Células-Tronco Neoplásicas/fisiologia , Neuroblastoma/patologia , Probenecid/administração & dosagem , Células da Side Population/efeitos dos fármacos , Células da Side Population/fisiologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Resistance and toxicity are the major barriers to successful cancer chemotherapies. Developing molecules that reduce drug resistance and improve antineoplastic effects is of great interest for cancer research; ideally, these substances should not affect the pharmacodynamics of the chemotherapeutic agent while providing a synergistic antineoplastic effect. In this study, we tested in vitro co-administration of the antineoplastic agents cisplatin or paclitaxel with probenecid, an anion channel inhibitor, in a panel of cancer cell lines to determine the cytotoxicity and synergistic effects of these drug combinations. In addition, we measured the clonogenicity and apoptotic index in these cells. We observed a synergistic interaction between probenecid and the chemotherapeutic agents, and increasing doses of probenecid resulted in a significant decrease in the effective doses of the chemotherapeutic agents. For the antineoplastic agent and probenecid combinations, we found increased cell death, reduced colony formation, and a higher number of apoptotic cells, compared with treatment of cisplatin or paclitaxel alone. Further research is necessary to elucidate the molecular mechanisms by which the synergistic effect occurs. If these synergistic effects can be reproduced in vivo, the co-administration of probenecid with different chemotherapeutic agents may provide a valid treatment in patients with chemotherapy resistance.