The Regulating Effect of Autophagy-Related MiRNAs in Kidney, Bladder, and Prostate Cancer

Deregulated microRNAs Involved in Prostate Cancer Aggressiveness and Treatment Resistance Mechanisms

Prostate cancer (PCa) is the most frequently diagnosed cancer and the second leading cause of cancer deaths among American men. Complex genetic and epigenetic mechanisms are involved in the development and progression of PCa. MicroRNAs (miRNAs) are short noncoding RNAs that regulate protein expression at the post-transcriptional level by targeting mRNAs for degradation or inhibiting protein translation. In the past two decades, the field of miRNA research has rapidly expanded, and emerging evidence has revealed miRNA dysfunction to be an important epigenetic mechanism underlying a wide range of diseases, including cancers. This review article focuses on understanding the functional roles and molecular mechanisms of deregulated miRNAs in PCa aggressiveness and drug resistance based on the existing literature. Specifically, the miRNAs differentially expressed (upregulated or downregulated) in PCa vs. normal tissues, advanced vs. low-grade PCa, and treatment-responsive vs. non-responsive PCa are discussed. In particular, the oncogenic and tumor-suppressive miRNAs involved in the regulation of (1) the synthesis of the androgen receptor (AR) and its AR-V7 splice variant, (2) PTEN expression and PTEN-mediated signaling, (3) RNA splicing mechanisms, (4) chemo- and hormone-therapy resistance, and (5) racial disparities in PCa are discussed and summarized. We further provide an overview of the current advances and challenges of miRNA-based biomarkers and therapeutics in clinical practice for PCa diagnosis/prognosis and treatment.

Non-coding RNA-mediated autophagy in cancer: A protumor or antitumor factor?

Autophagy, usually referred to as macroautophagy, is a cytoprotective behavior that helps cells, especially cancer cells, escape crises. However, the role of autophagy in cancer remains controversial. The induction of autophagy is favorable for tumor growth, as it can degrade damaged cell components accumulated during nutrient deficiency, chemotherapy, or other stresses in a timely manner. Whereas the antitumor effect of autophagy might be closely related to its crosstalk with metabolism, immunomodulation, and other pathways. Recent studies have verified that lncRNAs and circRNAs modulate autophagy in carcinogenesis, cancer cells proliferation, apoptosis, metastasis, and chemoresistance via multiple mechanisms. A comprehensive understanding of the regulatory relationships between ncRNAs and autophagy in cancer might resolve chemoresistance and also offer intervention strategies for cancer therapy. This review systematically displays the regulatory effects of lncRNAs and circRNAs on autophagy in the contexts of cancer initiation, progression, and resistance to chemo- or radiotherapy and provides a novel insight into cancer therapy.

Regulation of autophagy by miRNAs in human diseases

Autophagy is a homeostatic process designed to eliminate dysfunctional and aging organelles and misfolded proteins through a well-concerted pathway, starting with forming a double-membrane vesicle and culminating in the lysosomal degradation of the cargo enclosed inside the mature vesicle. As a vital sentry of cellular health, autophagy is regulated in every human disease condition and is an essential target for non-coding RNAs like microRNAs (miRNAs). miRNAs are short oligonucleotides that specifically bind to the 3'-untranslated region (UTR) of target mRNAs, thus leading to mRNA silencing, degradation, or translation blockage. This review summarizes the recent findings regarding the regulation of autophagy and autophagy-related genes by different miRNAs in various pathological conditions, including cancer, kidney and liver disorders, neurodegeneration, cardiovascular disorders, infectious diseases, aging-related conditions, and inflammation-related diseases. As miRNAs are being identified as prime regulators of autophagy in human disease, pharmacological molecules and traditional medicines targeting these miRNAs are also being tested in disease models, thus initiating a new series of therapeutic interventions targeting autophagy.

Identification of autophagy-associated miRNA signature for the cervical squamous cell cancer and high-grade cervical intraepithelial lesions

Cervical cancer markedly threatens women's health worldwide and currently ranks fourth leading cause of cancer mortality in women according to recent global cancer statistics. Recent advances have proven that not only tumor suppressor and oncogenes but also non-coding RNAs including micro RNAs (miRNAs) have significant impact in the development and progression of cervical cancers. Previous studies have identified many cancer-specific miRNAs for the early detection of cervical cancers. However, the diagnostic and prognostic use of autophagy-associated miRNAs for the cervical squamous cell cancer (SCC) cases and high-grade squamous intraepithelial lesion (HSIL) have not been uncovered. In the present study, we revealed that miRNAs are differentially expressed in both cervical SCC and HSIL. A total of 35 HSIL, 35 cervical SCC and 30 healthy controls were enrolled for the present study. Total RNA including miRNAs were isolated from the FFPE tissue samples and miRNA expression levels were quantified by quantitative PCR. Predicted miRNA targets of autophagy related genes were determined using miRNA-target prediction algorithms. MiR-143, miR-372, miR-375 and miR-30c were markedly downregulated in HSIL and cervical SCC. MiR-130a was significantly upregulated in the cervical SCC group compared to HSIL and control groups. MiR-30a, miR-520e, miR-548c and miR-372 were significantly associated with the overall survival of cervical SCC patients and these miRNAs were determined to be significant diagnostic markers as revealed by ROC analysis. Together, these results indicate that autophagy-associated miRNAs are potentially valuable for the differential diagnosis and targeted therapy to cervical cancer.