Roles of MicroRNAs in Esophageal Squamous Cell Carcinoma Pathogenesis

Circular RNA circ-SLC7A5 Functions as a Competing Endogenous RNA to Impact Cell Biological Behaviors in Esophageal Squamous Cell Carcinoma (ESCC)

BACKGROUND

Circular RNAs (circRNAs) have profound effects on establishment and pathogenesis of esophageal squamous cell carcinoma (ESCC). Here, we defined whether circRNA solute carrier family 7 member 5 (circ-SLC7A5, also called hsa_circ_0040796) is causally involved in the pathogenesis of ESCC.

METHODS

Circ-SLC7A5, microRNA (miR)-874-3p and coronin-1C (CORO1C) expression levels were gauged by qRT-PCR or immunoblotting. Cell functional phenotypes were tested by colony formation, EdU, flow cytometry, transwell and wound-healing assays. RNA immunoprecipitation (RIP) and dual-luciferase reporter assays were applied to ascertained circ-SLC7A5/miR-874-3p and miR-874-3p/CORO1C relationships.

RESULTS

Circ-SLC7A5 was highly expressed in human ESCC. Circ-SLC7A5 depletion impaired cell growth, migration, invasiveness, and promoted apoptosis. Circ-SLC7A5 knockdown diminished ESCC cell tumorigenicity. Mechanistically, circ-SLC7A5 contained a binding site for miR-874-3p. Also, miR-874-3p was responsible for circ-SLC7A5's function in ESCC cells. CORO1C was a direct miR-874-3p target. Circ-SLC7A5 functioned as a competing endogenous RNA (ceRNA) to control CORO1C by competing for shared miR-874-3p. Furthermore, CORO1C knockdown phenocopied miR-874-3p overexpression in impacting the biological behaviors of ESCC cells.

CONCLUSION

These findings identify circ-SLC7A5 as a crucial modulator of ESCC cells and establish a novel circ-SLC7A5/miR-874-3p/CORO1C ceRNA network in ESCC.

microRNA-497-mediated Smurf2/YY1/HIF2α axis in tumor growth and metastasis of esophageal squamous cell carcinoma

Aberrant expression of microRNA-497 (miR-497) is associated with tumor progression, but the molecular mechanisms in tumorigenesis remain largely unknown. Here, we report that miR-497 expression is downregulated in esophageal squamous cell carcinoma (ESCC) clinical samples. Consistently, upregulation of miR-497 inhibits ESCC cell malignant properties and tumor growth in vivo. Importantly, we uncovered that miR-497 upregulation suppressed ESCC cell growth and tumor growth by inhibiting Smurf2. Mechanistically, we showed that Smurf2 was a target of miR-497, and mediated YY1 expression to elevate HIF2α expression, thereby enhancing the malignancy of ESCC cells. Together, our study uncovered the role of the miR-497-mediated Smurf2/YY1/HIF2α axis in tumor growth and metastasis, which might provide potential therapeutic targets for human ESCC.

Identification of a novel circ_0001946/miR-1290/SOX6 ceRNA network in esophageal squamous cell cancer

Background

Circular RNAs (circRNAs) can function as competing endogenous RNAs (ceRNAs) to impact the development of esophageal squamous cell cancer (ESCC). Human circ_0001946 has been identified as a potential anticancer factor in ESCC, yet our understanding of its molecular basis remains limited.

Methods

Circ_0001946, microRNA (miR)‐1290 and SRY‐box transcription factor 6 (SOX6) were quantified by quantitative reasl‐time PCR (qRT‐PCR) or immunoblotting. Cell proliferation was assessed by CCK‐8 and EDU assays. Cell apoptosis and invasion were evaluated by flow cytometry and transwell assays, respectively. Cell migration was detected by transwell and wound‐healing assays. The direct relationship between miR‐1290 and circ_0001946 or SOX6 was determined by dual‐luciferase reporter and RNA immunoprecipitation (RIP) assays. Xenograft model assays were used to assess the role of circ_0001946 in tumor growth.

Results

Circ_0001946 expression was attenuated in human ESCC, and circ_0001946 increase impeded cell proliferation, invasion, migration and enhanced apoptosis in vitro. Moreover, circ_0001946 increase diminished xenograft growth in vivo. Mechanistically, circ_0001946 bound to miR‐1290, and re‐expression of miR‐1290 reversed circ_0001946‐dependent cell properties. SOX6 was a miR‐1290 target and it was responsible for the regulation of miR‐1290 in cell properties. Furthermore, circ_0001946 functioned as a ceRNA to regulate SOX6 expression via miR‐1290.

Conclusion

Our findings uncover an undescribed molecular mechanism, the circ_0001946/miR‐1290/SOX6 ceRNA crosstalk, for the anti‐ESCC activity of circ_0001946.

Anaplastic Thyroid Carcinoma: Current Issues in Genomics and Therapeutics

PURPOSE OF REVIEW

Anaplastic thyroid carcinoma is a type of thyroid carcinoma with the most aggressive biological behaviour amongst thyroid cancer. Here, we review the current genomic and the impacts of advances in therapies to improve the management of patients with the cancer.

RECENT FINDINGS

Common mutations being identified in anaplastic thyroid carcinoma are p53 and TERT promoter mutations. Other common mutated genes included BRAF, RAS, EIF1AX, PIK3CA, PTEN and AKT1, SWI/SNF, ALK and CDKN2A. Changes in expression of different microRNAs are also involved in the pathogenesis of anaplastic thyroid carcinoma. Curative resection combined with radiotherapy and combination chemotherapies (such as anthracyclines, platins and taxanes) has been shown to have effects in the treatment of some patients with anaplastic thyroid carcinoma. Newer molecular targeted therapies in clinical trials target mostly the cell membrane kinase and downstream proteins. These include targeting the EGFR, FGFR, VEGFR, c-kit, PDGFR and RET on the cell membrane as well as VEGF itself and the downstream targets such as BRAF, MEK and mTOR. Immunotherapy is also being tested in the cancer. Updated knowledge of genomic as well as clinical trials on novel therapies is needed to improve the management of the patients with this aggressive cancer.