Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment.

https://www.mdpi.com/2073-4409/8/8/840/pdf

Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies.

Non-coding RNAs can exert significant roles various cancers, including NSCLC. Previously, we indicated that lncRNA DGCR5 can promote lung cancer progression through inhibiting hsa-mir-22-3p. In our current study, we investigated the role of DGCR5 in cancer stem cell-like properties of NSCLC. CSCs have been recognized as the frequent cause of tumor metastasis, tumor recurrence, and chemotherapy resistance. Here, lung cancer stem cells were successfully enriched from the parental NSCLC A549, H460, and H1299 cells by using tumor sphere formation assays and side population (SP) assays. We observed that DGCR5 was up-regulated in the enriched CSCs of NSCLC. DGCR5 can inhibit the stemness of NSLCL while overexpression of DGCR5 promoted CSC-like traits. In addition, miR-330-5p was predicted as target of DGCR5 and the correlation between them was validated by dual-luciferase reporter assay, RIP assay, and RNA pull-down assay. Meanwhile, it was found that miR-330-5p was decreased in CSCs of NSCLC. miR-330-5p mimics repressed the stemness while miR-330-5p inhibition enhanced CSC-like properties by targeting CD44. Taken these together, DGCR5 can act as a crucial regulator of CSCs in NSCLC by modulating miR-330-5p/CD44 axis.

LncRNA DGCR5 contributes to CSC-like properties via modulating miR-330-5p/CD44 in NSCLC.

Oral cancer is one of the most frequent malignant diseases worldwide, and areca nut is a primary carcinogen causing this cancer in Southeast Asia. It has been widely reported that areca nut induced several cytotoxic effects in oral cells, including ROS generation, inflammation, tissue hypoxia, DNA damage, and cell invasion. Recently, through chronic exposure model, more extensive pathological effects due to areca nut have been found. These include the induction of autophagy, promotion of epithelial- mesenchymal transition, and facilitation of cancer stemness conversion. Clinical findings support these adverse effects. Oral submucosal fibrosis, a premalignant condition, is prevalent in the area with habitual chewing of areca nuts. Consistently, oral cancer patients with habitual chewing areca nut exhibit more aggressive phenotypes, including resistance to chemo-radiotherapy. In this review, we comprehensively discuss and concisely summarize the up-to-date molecular and cellular mechanisms by which areca nuts contribute to malignant transformation. This review may provide critical information regarding clinical applications in risk assessment, disease prevention, diagnosis, and personalized therapeutics for areca nut-induced oral malignancy.

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Multifaceted Mechanisms of Areca Nuts in Oral Carcinogenesis: the Molecular Pathology from Precancerous Condition to Malignant Transformation.

Emerging evidence show that long noncoding RNAs (lncRNAs) play critical roles in tumor development. LincRNA-ROR (linc-ROR) is known to promote tumor progress in several human cancers, including hepatocellular carcinoma (HCC). Nevertheless, the roles of linc-ROR in HCC metastasis and its underlying mechanisms remain fully unclear. In the present study, we showed that linc-ROR was upregulated in HCC tissues and high linc-ROR expression level predicted poor prognosis. Functionally, linc-ROR significantly induced epithelial-mesenchymal transition (EMT), and increased in vitro invasion and in vivo metastasis of HCC cells. Mechanistically, linc-ROR acted as a sponge for miR-145 to de-repress the expression of target gene ZEB2, thereby inducing EMT and promoting HCC metastasis. Collectively, our research indicates the potential of linc-ROR as a vital therapeutic target for the treatment of aggressive and metastatic HCC.

/pdf/the-lincrna-ror-mir-145-axis-promotes-invasion-and-2vz4xjqcq6.pdf

The lincRNA-ROR/miR-145 axis promotes invasion and metastasis in hepatocellular carcinoma via induction of epithelial-mesenchymal transition by targeting ZEB2.

Cancer-associated fibroblasts (CAFs) play critical roles in cancer progression and treatment failure. CAFs display extreme phenotypic heterogeneity and functional diversity. Some subpopulations of CAFs have the ability to reconstitute cancer stemness by promoting the expansion of cancer stem cells (CSCs) or by inducing the generation of CSCs from differentiated cancer cells. CAFs regulate cancer stemness in different types of solid tumors by activating a wide array of CSC-related signaling by secreting proteins and exosomes. As feedback, the CSCs can also induce the proliferation and further activation of CAFs to promote their CSC-supporting activities, thus completing the loop of CAF-CSC crosstalk. Current research on targeting CAF-CSC crosstalk could be classified into (i) specific depletion of CAF subpopulations that have CSC-supporting activities and (ii) targeting molecular signaling in CAF-CSC crosstalk, such as the IL6/STAT3, TGF-β/SDF-1/PI3K, WNT/β-catenin, HGF/cMET and SHH/Hh pathways. Strategies targeting CAF-CSC crosstalk may open new avenues for overcoming cancer progression and therapeutic resistance.

Therapeutic targeting of the crosstalk between cancer-associated fibroblasts and cancer stem cells.

// Tung Yuan Wang 1, * , Chih-Yu Peng 1, 2, * , Shiuan-Shinn Lee 4 , Ming-Yung Chou 1, 2, 3 , Cheng-Chia Yu 1, 2, 3 , Yu-Chao Chang 1, 2 1 School of Dentistry, Chung Shan Medical University, Taichung, Taiwan 2 Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan 3 Institute of Oral Sciences, Chung Shan Medical University, Taichung, Taiwan 4 School of Public Health, Chung Shan Medical University, Taichung, Taiwan * These authors contributed equally to this work Correspondence to: Cheng-Chia Yu, email: ccyu@csmu.edu.tw Yu-Chao Chang, email: cyc@csmu.edu.tw Keywords: arecoline, cancer stemness, oral squamous cell carcinomas Received: November 09, 2015      Accepted: August 13, 2016      Published: August 20, 2016 ABSTRACT Oral squamous cell carcinoma (OSCC), one of the most deadliest malignancies in the world, is caused primarily by areca nut chewing in Southeast Asia. The mechanisms by which areca nut participates in OSCC tumorigenesis are not well understood. In this study, we investigated the effects of low dose long-term arecoline (10 μg/mL, 90-days), a major areca nut alkaloid, on enhancement cancer stemness of human oral epithelial (OE) cells. OE cells with chronic arecoline exposure resulted in increased ALDH1 population, CD44 positivity, stemness-related transcription factors (Oct4, Nanog, and Sox2), epithelial-mesenchymal transdifferentiation (EMT) traits, chemoresistance, migration/invasiveness/anchorage independent growth and in vivo tumor growth as compared to their untreated controls. Mechanistically, ectopic miR-145 over-expression in chronic arecoline-exposed OE (AOE) cells inhibited the cancer stemness and xenografic. In AOE cells, luciferase reporter assays further revealed that miR-145 directly targets the 3′ UTR regions of Oct4 and Sox2 and overexpression of Sox2/Oct4 effectively reversed miR-145-regulated cancer stemness-associated phenomenas. Additionally, clinical results further revealed that Sox2 and Oct4 expression was inversely correlated with miR-145 in the tissues of areca quid chewing-associated OSCC patients. This study hence attempts to provide novel insight into areca nut-induced oral carcinogenesis and new intervention for the treatment of OSCC patients, especially in areca nut users.

/pdf/acquisition-cancer-stemness-mesenchymal-transdifferentiation-303lh7d5gx.pdf

Acquisition cancer stemness, mesenchymal transdifferentiation, and chemoresistance properties by chronic exposure of oral epithelial cells to arecoline.

Background The let-7 family of microRNAs has been considered as tumor suppressors in various cancers; however, the role of let-7c in oral squamous cell carcinoma has not been determined yet. Methods In this study, phenotypical behaviors and the radio/chemoresistance were examined subsequent to overexpression of let-7c. In addition, the expression of let-7c in cancer stem cells (CSCs) was evaluated and the effect of let-7c on stemness characteristics was assessed. Also, luciferase activity assays were performed to test whether interleukin (IL)-8 was a putative target of let-7c. Results Our results confirmed that the expression of let-7c in CSCs was reduced, while overexpression of let-7c attenuated the oncogenicity. Moreover, ectopic expression of let-7c in CSCs downregulated the stemness hallmarks and the radio/chemoresistance. Expression and secretion of IL-8 in oral CSCs were both reduced following overexpression of let-7c. Besides, the inhibitory effect of let-7c on various stemness phenotypes was reverted by IL-8, indicating that lower expression of let-7c may confer higher cancer stemness through a failure to downregulate IL-8. Conclusion These findings revealed the significance of let-7c in the contribution of oral cancer stemness and radio/chemoresistance. Targeting let-7c and its downstream IL-8 may be beneficial to prevent cancer recurrence and metastasis of oral squamous cell carcinoma.

Let-7c restores radiosensitivity and chemosensitivity and impairs stemness in oral cancer cells through inhibiting interleukin-8.

// Tung Yuan Wang 1, * , Cheng-Chia Yu 1, 2, 3, * , Pei-Ling Hsieh 3 , Yi-Wen Liao 1 , Chuan-Hang Yu 1, 2 and Ming-Yung Chou 1, 2 1 School of Dentistry, Chung Shan Medical University, Taichung, Taiwan 2 Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan 3 Institute of Oral Sciences, Chung Shan Medical University, Taichung, Taiwan * These authors have contributed equally to this work Correspondence to: Ming-Yung Chou, email: myc@csmu.edu.tw Chuan-Hang Yu, email: tao2008@csmu.edu.tw Keywords: oral squamous cell carcinomas, immunomodulatory protein GMI, cancer stem cells, chemoresistance, IL-6/Stat3 signaling Received: May 04, 2017      Accepted: June 19, 2017      Published: July 31, 2017 ABSTRACT Cancer stem cells (CSCs) have been identified to exert tumor-initiating ability, resulting in the recurrence, metastasis and chemoresistance of oral squamous cell carcinomas. In the present study, we showed that GMI, an immunomodulatory protein from Ganoderma microsporum , induc ed a cytotoxic effect in oral carcinomas stem cells (OCSCs). Treatment of GMI dose-dependently inhibited the expression of CSC markers, including ALDH1 activity and CD44 positivity. Moreover, GMI suppressed the self-renewal property, colony formation, migration, and invasion abilities as well as potentiated chemo-sensitivity in OCSCs. Our results suggested that the tumor suppressive effect of GMI was mediated through inhibition of IL-6/Stat3 signaling pathway. Furthermore, tumor growth was reduced in mice bearing xenograft tumors after oral administration of GMI. Taken together, we demonstrated the anti-CSC effect of GMI in oral cancer and GMI may serve as a natural cisplatin adjuvant to prevent cancer recurrence.

/pdf/gmi-ablates-cancer-stemness-and-cisplatin-resistance-in-oral-394yph0237.pdf

Tung Yuan Wang

Papers

Acquisition cancer stemness, mesenchymal transdifferentiation, and chemoresistance properties by chronic exposure of oral epithelial cells to arecoline.

Let-7c restores radiosensitivity and chemosensitivity and impairs stemness in oral cancer cells through inhibiting interleukin-8.

GMI ablates cancer stemness and cisplatin resistance in oral carcinomas stem cells through IL-6/Stat3 signaling inhibition.