About this Research Topic
MicroRNAs are a group of short, single-stranded, non-coding RNAs that modulate gene expression,operating at a post-transcriptional level through complex base-pairing within mRNA molecules, leading to their cleavage, destabilization or translational repression. Past research has shown that miRNAs are involved in different cellular and molecular mechanisms such as proliferation, differentiation and apoptosis. Down-regulated gene expression induced by miRNAs reportedly plays a partial role in normal embryonic stem cell function as well as in the subtle governing of both physiological and pathological responses such as DNA injury reaction and epigenetic changes.
Additional studies have shown that microRNAs not only influence the receptivity of various cells to signalling particles such as TGF- β and EGF, but also play an important role in cellular signaling cascades like Notch, Hedgehog and Wnt. In this manner, miRNAs act as mediators that, besides ensuring normal cell function, are also involved in cancer progression and various pathological conditions. The great variety of potential targets of miRNA creates numerous associations that seem to assemble an intricate network of regulators entangled with other molecular systems like signal transduction networks. However, by what means miRNAs regulate cellular signaling cascades is still not evident.
Many cancer types have been shown to associate modifications in miRNA expression. For instance, the liver-specific miR-122 is frequently repressed in hepatocellular carcinoma, while a high expression level of the miR-17-92 family is correlated with a variety of human cancers, particularly leukemias and lymphomas. Changes in miRNA have also been shown to affect cholesterol and triglyceride concentrations, with reduced levels observed in mice with targeted deletion of miR-122. Moreover, notable connections between miRNAs and viral families have also been made, most significantly in the herpesvirus family.
It is beyond doubt that miRNA alterations pose great potential for diagnosis based on their molecular signatures. Therefore, currently, one of the main objectives consists of developing miRNA signatures for enabling diagnosis, establishing the origin of malignancy and predicting therapy response as well as drug resistance. This Research Topic hopes to contribute to elucidating the molecular pathways that miRNAs play a role in, with the aim to shed light not only on carcinogenesis, from initiation to malignant conversion, but also on various other diseases, making it a target of future research. Authors are welcome to submit a wide range of article types including, but not limited to, Original Research, Opinions, Reviews and Hypothesis & Theory.
Keywords: MicroRNA, Signaling, miRNA, Molecular Signature, Carcinogenesis
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