Recent studies have highlighted the pivotal role of microRNAs (miRNAs) in tumorigenesis. A growing body of data implicates that miRNAs
are critically involved in regulation of cell growth, cell cycle, apoptosis, migration, invasion, angiogenesis, metastasis, epithelial to mesenchymal
transition (EMT), cancer stem cell renewal, and drug resistance. Therefore, our special issue reviewed the important role of miRNAs
in the development and progression of human cancers.
It has been accepted that miRNAs play an essential role in human malignancies. Dr. Markel et al. reviewed the diverse roles of miRNAs in
regulation of cell cycle, proliferation, migration, invasion and drug resistance in melanoma cell biology . Moreover, Dr. Zhou et al. discussed
the oncogenic miRNAs in the genesis of leukemia and lymphoma, suggesting that miRNAs could be novel targets for anti-leukemia
and anti-lymphoma drug discovery . Dr. Sarkar et al. summarized the function of miRNAs in breast cancer tumorigenesis and metastasis,
and provided the current knowledge of miRNAs as molecular targets for diagnosis, prognosis and therapy in breast cancer . Emerging evidence
has suggested that miRNAs exert its biological functions through governing key signaling pathways. To support this concept, Dr. Azmi
et al. summarized that a number of miRNAs control Kras-PAK4 (p21 activated kinase 4) axis in cancer . Dr. Xie et al. discussed that
miRNAs are key players in pancreatic cancer initiation and progression through regulating FOXM1 signaling pathway . Furthermore, Dr.
Batra and colleagues summarized miRNAs as biomarkers for prognosis and diagnosis of gastrointestinal cancers and gastrointestinal tract
associated organs including esophagus, gastric, liver, pancreas, and colon . Intriguingly, Dr. Lu et al. discussed the developments on the
regulatory role of miRNAs in circulating tumor cells and thrombosis, suggesting that targeting miRNAs could be useful for the treatment and
prevention of metastasis and thrombosis in cancer .
It is noteworthy that miRNAs have been demonstrated to be involved in EMT progress. Dr. Yang et al. described that multiple miRNAs regulated
EMT-inducing transcription factors such as Notch and TGF-β, leading to regulation of EMT in cancer . Since EMT and miRNAs are
associated with cancer stem cells (CSCs), Dr. Watabe et al. discussed how miRNAs regulate CSCs through different self-renewal pathways in
various types of human cancers . More importantly, Dr. Croce et al. discussed approaches towards therapeutic miRNA-based intervention
including viral or non-viral approaches of miRNA replacement therapy . Remarkably, Dr. Fan et al. summarized the implication of miRNAs
in clinical use and challenge for miRNA based therapy such as miRNA delivery . Notably, Dr. Wang et al. demonstrated that natural
agent genistein down-regulated oncomiR-27a in pancreatic cancer cells, indicating that genistein could be a miR-27a inhibitor . Dr. Chen
et al. observed that arsenic trioxide exerts its anti-tumor activity partly through regulation of miR-125b in glioma cells . Taken together,
targeting miRNAs could be a novel strategy for treatment of cancer.
Lastly, as the editor, I would like to thank the authors for their contributions. I also would like to appreciate the referees for their timely reviews.
We hope that this special issue will help identify novel therapeutic targets to treat human cancers.