Papel da melatonina na modulação do miR-148b e miR-210 em linhagem triplo-negativa de mama
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Data
2017-11-10
Autores
Ferreira, Lívia Carvalho [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O câncer de mama apresenta altas taxas de incidência e também de mortalidade, sendo a neoplasia mais comum entre as mulheres. MicroRNAs (miRNAs) são pequenas moléculas de RNAs não codificantes que desempenham papel fundamental na regulação gênica. Estudos recentes têm demonstrado que miRNAs estão diretamente envolvidos na iniciação e progressão de vários tipos tumorais, incluindo o câncer de mama. Diversos miRNAs têm sido descritos como promotores ou supressores tumorais, podendo estar associados ao crescimento do tumor e metástase. Atualmente, tem sido demonstrado que a administração exógena da melatonina, um hormônio naturalmente secretado pela glândula pineal, apresenta diversos efeitos oncostáticos em diferentes tipos tumorais. Assim, o objetivo do presente estudo foi avaliar o papel da melatonina em uma possível via metastática envolvendo a regulação de miRNAs em células da linhagem de câncer de mama metastática e triplo-negativa MDA-MB-231. Inicialmente, a expressão de 384 miRNAs foi avaliada utilizando placas “Taqman Low-density Array” (TLDA). Para futuras validações, foram selecionados apenas miRNAs que apresentaram fold change >1,5 e <0,5. Os resultados demonstraram que a melatonina modulou a expressão de 17 miRNAs (11 superexpressos e 6 inibidos). Dentre os miRNAs modulados pela melatonina, miR-148b e miR-210 foram confirmados por qRT-PCR, selecionados e utilizados para investigações funcionais. As células MDAMB-231 foram então transfectadas para inibição de miR-148b e/ou miR-210 (permanente ou transiente, respectivamente), e avaliadas após tratamento com melatonina. Em seguida foram avaliadas a taxa de migração e expressão proteica de cMyc, possível gene alvo de miR-148b e miR-210. Os resultados demonstraram que a melatonina foi capaz de reduzir a expressão de c-Myc e afetar a taxa de migração das células modificadas ou não com miR-148b. No entanto, nenhum efeito sobre c-Myc ou migração foi observado em células modificadas para miR-148b, quando comparadas as células controle. No que se refere ao miR-210, a melatonina alterou a expressão de cMyc e migração celular, nas células tratadas com melatonina ou expressando anti-miR210. Em resumo, nossos resultados demonstraram que apesar da melatonina influenciar na modulação positiva do miR-148b e miR-210 em células tumorais de mama triplonegativas, esta regulação não foi necessariamente causativa para alterar a expressão de c-Myc ou diminuir a taxa de migração destas células. Nossos resultados confirmam o efeito da melatonina na inibição da proliferação e migração celular, especialmente em células triplo-negativas, sugerindo seu importante papel no controle da progressão tumoral. No entanto, ainda é necessário estabelecer uma ligação direta entre as modulações de certas proteínas ou miRNAs com os efeitos da melatonina.
Breast cancer has high rates of incidence and mortality, and it is the most common cancer among women. MicroRNAs (miRNAs) are small molecules of non-coding mRNA that play a key role in gene regulation. Recent studies have shown that miRNAs are directly involved in the initiation and progression of various tumor types, including breast cancer. Several miRNAs have been described as promoters or suppressors of metastasis and may be associated with tumor growth and metastasis. Exogenous administration of melatonin, a hormone secreted by the pineal gland, has been shown several oncostatics effects on different types of cancers. Herein, we investigated if the antimetastatic effects of melatonin were coordinated by miRNAs involved in tumor progression. The expression of 384 miRNAs was measured using Taqman Low-density Array (TLDA) cards. Considering the cut-off we imposed (fold change >1.5 and (fold change >1.5 and<0.5) were evidenced the modulation of 17 miRNAs (11 up and 6 down). Among all miRNAs modulated, the selected miR-210 and miR-148b were further confirmed by qRT-PCR and tested for functional investigations. First, we engineered cells for miR-210 or miR-148b overexpression or depletion (stable or transient), then we evaluated the effect of melatonin on c-Myc protein expression and migration. Melatonin reduced c-Myc expression and migration in cell depleted or not for miR-148b. However no effect on c-Myc or migration was observed for cells depleted for miR-148b when compared with control cells. c-Myc and migration were reduced in cells treated with melatonin or expressing anti-miR-210 (depleted). In summary, our results suggest that, even if melatonin alters miRNA expression, the modulations of the miRNAs we studied, miR-210 and miR-148b, are not essential for melatonin inhibition of cell migration and c-Myc expression. One of the hypotheses is that c-Myc is not a target of these miRNAs in MDA-MB-231 cells, and it is believed that melatonin effects on miRNAs could be just “epiphenomenon” due to general Dicer/Drosha deregulations. Nevertheless, melatonin remains a powerful molecule for metastatic traits inhibition, which modulates a set of protein-coding genes, such as c-Myc. However, a direct link between expression modulations of certain proteins or miRNAs and melatonin effects has still to be established.
Breast cancer has high rates of incidence and mortality, and it is the most common cancer among women. MicroRNAs (miRNAs) are small molecules of non-coding mRNA that play a key role in gene regulation. Recent studies have shown that miRNAs are directly involved in the initiation and progression of various tumor types, including breast cancer. Several miRNAs have been described as promoters or suppressors of metastasis and may be associated with tumor growth and metastasis. Exogenous administration of melatonin, a hormone secreted by the pineal gland, has been shown several oncostatics effects on different types of cancers. Herein, we investigated if the antimetastatic effects of melatonin were coordinated by miRNAs involved in tumor progression. The expression of 384 miRNAs was measured using Taqman Low-density Array (TLDA) cards. Considering the cut-off we imposed (fold change >1.5 and (fold change >1.5 and<0.5) were evidenced the modulation of 17 miRNAs (11 up and 6 down). Among all miRNAs modulated, the selected miR-210 and miR-148b were further confirmed by qRT-PCR and tested for functional investigations. First, we engineered cells for miR-210 or miR-148b overexpression or depletion (stable or transient), then we evaluated the effect of melatonin on c-Myc protein expression and migration. Melatonin reduced c-Myc expression and migration in cell depleted or not for miR-148b. However no effect on c-Myc or migration was observed for cells depleted for miR-148b when compared with control cells. c-Myc and migration were reduced in cells treated with melatonin or expressing anti-miR-210 (depleted). In summary, our results suggest that, even if melatonin alters miRNA expression, the modulations of the miRNAs we studied, miR-210 and miR-148b, are not essential for melatonin inhibition of cell migration and c-Myc expression. One of the hypotheses is that c-Myc is not a target of these miRNAs in MDA-MB-231 cells, and it is believed that melatonin effects on miRNAs could be just “epiphenomenon” due to general Dicer/Drosha deregulations. Nevertheless, melatonin remains a powerful molecule for metastatic traits inhibition, which modulates a set of protein-coding genes, such as c-Myc. However, a direct link between expression modulations of certain proteins or miRNAs and melatonin effects has still to be established.
Descrição
Palavras-chave
câncer de mama, metástase, miRNAs, melatonina, breast cancer, metastasis, melatonin, miRNA