HK2 and LDHA upregulation mediate hexavalent chromium-induced carcinogenesis, cancer development and prognosis through miR-218 inhibition.

Hexavalent chromium [Cr(VI)] is one of the most common environmental contaminants due to its tremendous industrial applications, but its effects and mechanism remain to be investigated. Our previous studies showed that Cr(VI) exposure caused malignant transformation and tumorigenesis. This study showed that glycolytic proteins HK2 and LDHA levels were statistically significant changed in blood samples of Cr(VI)-exposed workers and in Cr-T cells compared to the control subjects and parental cells. HK2 and LDHA knockdown inhibited cell proliferation and angiogenesis, and higher HK2 and LDHA expression levels are associated with advanced stages and poor prognosis of lung cancer. We found that miR-218 levels were significantly decreased and miR-218 directly targeted HK2 and LDHA for inhibiting their expression. Overexpression of miR-218 inhibited glucose consumption and lactate production in Cr-T cells. Further study found that miR-218 inhibited tumor growth and angiogenesis by decreasing HK2 and LDHA expression in vivo. MiR-218 levels were negatively correlated with HK2 and LDHA expression levels and cancer development in human lung and other cancers. These results demonstrated that miR-218/HK2/LDHA pathway is vital for regulating Cr(VI)-induced carcinogenesis and human cancer development.

Biphasic function of GSK3ß in gefitinib­resistant NSCLC with or without EGFR mutations.

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib, are effective in the treatment of non-small cell lung cancer (NSCLC) harboring EGFR mutations. However, the mechanism underlying acquired resistance to EGFR-TKIs remains largely unknown. Therefore, the present study generated gefitinib-resistant PC-9 (PC-9G) cells, which were revealed to be more resistant to gefitinib-induced reductions in proliferation, migration and invasion, and increases in apoptosis, and had no detectable EGFR mutations compared with the control PC-9 cell line. In addition, the present study performed genome-wide transcriptomic analysis of differentially expressed genes between PC-9 and PC-9G cell lines. Cell proliferation, colony formation, invasion, migration and flow cytometry analyses were also performed. The genome-wide transcriptomic analysis revealed that glycogen synthase kinase 3ß (GSK3ß) was downregulated in PC-9G cells compared with that in PC-9 cells. Furthermore, GSK3ß overexpression increased the proliferation, migration and invasion of PC-9 and H1975 gefitinib-resistant cells. Conversely, overexpression of GSK3ß suppressed the proliferation, migration and invasion of PC-9G cells. Furthermore, AKT inhibition reduced the proliferation, migration and invasion, and induced the apoptosis of PC-9, PC-9G and H1975 cells, the effects of which were reversed following AKT activation; notably, the tumor suppressor function of GSK3ß was inconsistent with the tumor promotor role of the AKT pathway in PC-9G cells without EGFR mutation. The present study may provide novel insights into the distinctive role of GSK3ß in gefitinib-resistant NSCLC with or without EGFR mutations, suggesting that a more detailed investigation on GSK3ß as a therapeutic target for gefitinib-resistant NSCLC may be warranted.

Corrigendum: Regulation of microrna-497-targeting AKT2 influences tumor growth and chemoresistance to cisplatin in lung cancer.

[This corrects the article DOI: 10.3389/fcell.2020.00840.].

MiRNA-30e downregulation increases cancer cell proliferation, invasion and tumor growth through targeting RPS6KB1.

Human esophagus carcinoma (EC) is one of the most common malignant tumors, especially in Africa and Asia including China. In EC initiation and progression, genetic and epigenetic aberrations have been reported to play a major role, but the underlying molecular mechanisms are largely unknown. In this study, the miR-30e levels were analyzed in human EC tissues and TCGA databases, and the results demonstrated that miR-30e expression in EC tissues was significantly decreased compared to adjacent normal tissues. To further investigate the role of miR-30e in cancer cells, we found that forced expression of miR-30e dramatically inhibited cell proliferation, invasion, tube formation, and colony formation of cancer cells. To determine the underlying mechanism of miR-30e, we found that RPS6KB1 was a direct target of miR-30e by binding to its 3'-UTR, which was verified by luciferase activity assay using reporters with wild-type miR-30e and its seed sequence mutant constructs and Western blotting assay. In vivo experiment showed that miR-30e overexpression significantly inhibited tumor growth and decreased RPS6KB1 expression in xenografts. In EC, high expression of RPS6KB1 in tumor tissues indicated poor prognosis of patients with less survival rate. High levels of RPS6KB1 and low levels of miR-30e closely correlated poor survival of patients with several other types of cancer. These findings show that miR-30e and its target RPS6KB1 are important in cancer development and clinical outcomes, and miR-30e/RPS6KB1 is a potential future therapeutic pathway for EC intervention.

Regulation of MicroRNA-497-Targeting AKT2 Influences Tumor Growth and Chemoresistance to Cisplatin in Lung Cancer.

BACKGROUND: MicroRNA-497 (miR-497) has been implicated in several cancers. Increasing studies demonstrate the role of AKT2 in cancers as an oncogene which is closely associated with tumor aggressiveness by enhancing cancer cell survival, migration and invasion However, miR-497/AKT2 axis in non-small cell lung cancer (NSCLC) remains unclear. METHODS: Quantitative real-time PCR (qRT-PCR) was used to quantify the expression of miR-497 and its target gene. The function of miR-497 in lung cancer was investigated through in vitro and in vivo assays (cell proliferation assay, cell migration assay, colony formation assay, flow cytometry assay, immunoblotting and tumorigenesis assay). Luciferase reporter assay was conducted to confirm the target gene of miR-497. RESULTS: In this study, we found that miR-497 was significantly downregulated in tumor tissues and blood samples of lung cancer patients. To understand the potential mechanism of miR-497 in inhibiting tumor growth, we showed that miR-497 blocked the activation of AKT2 and regulated cell proliferation, cell migration, colony formation and increases chemosensitivity of H1299 cells to cisplatin by inhibiting AKT2. MiR-497 also inhibited tumor growth and suppressed expression of AKT2 at the protein and mRNA levels in mouse xenograft tumors. CONCLUSION: Taken together, our findings indicated that miR-497 suppresses the tumor growth by targeting AKT2, and the miR-497/AKT2 axis is a potential therapeutic target for NSCLC intervention.

MiR-199a Inhibits Tumor Growth and Attenuates Chemoresistance by Targeting K-RAS via AKT and ERK Signalings.

Glioma is the most malignant brain tumors in the world, the function and molecular mechanism of microRNA-199a (miR-199a) in glioma is not fully understood. Our research aims to investigate miR-199a/K-RAS axis in regulation of glioma tumor growth and chemoresistance. The function of miR-199a in glioma was investigated through in vitro and in vivo assays. We found that miR-199a in tumor tissues of glioma patients was significantly downregulated in this study. Kinase suppressor of ras 1 (K-RAS), was indicated as a direct target of miR-199a, as well as expression levels of K-RAS were inversely correlated with expression levels of miR-199a in human glioma specimens. Forced expression of miR-199a suppressed AKT and ERK activation, decreased HIF-1α and VEGF expression, inhibited cell proliferation and cell migration, forced expression of K-RAS restored the inhibitory effect of miR-199a on cell proliferation and cell migration. Moreover, miR-199a renders tumor cells more sensitive to temozolomide (TMZ) via targeting K-RAS. In vivo experiment validated that miR-199a functioned as a tumor suppressor, inhibited tumor growth by targeting K-RAS and suppressed activation of AKT, ERK and HIF-1α expression. Taken together, these findings indicated that miR-199a inhibits tumor growth and chemoresistance by regulating K-RAS, and the miR-199a/K-RAS axis is a potential therapeutic target for clinical intervention in glioma.

Apigenin Inhibits IL-6 Transcription and Suppresses Esophageal Carcinogenesis.

Esophagus cancer is the seventh cause of cancer-related deaths globally. In this study, we analyzed interleukin 6 (IL-6) gene expression in human esophagus cancer patients and showed that IL-6 mRNA levels are significantly higher in tumor tissues and negatively correlated with overall survival, suggesting that IL-6 is a potential therapeutic target for esophagus cancer. We further demonstrated that apigenin, a nature flavone product of green plants, inhibited IL-6 transcription and gene expression in human esophagus cancer Eca-109 and Kyse-30 cells. Apigenin significantly and dose-dependently inhibited cell proliferation and promoted apoptosis while stimulating the cleaved PARP (poly ADP-ribose polymerase) (C-PARP) and caspase-8 expression. It suppressed VEGF (Vascular endothelial growth Factor) expression and tumor-induced angiogenesis. Pretreatment of cells with IL-6 could completely reverse apigenin-induced cellular changes. Finally, using a preclinical nude mice model subcutaneously xenografted with Eca-109 cells, we demonstrated the in vivo antitumor activity and mechanisms of apigenin. Taken together, this study revealed for the first time that apigenin is a new IL-6 transcription inhibitor and that inhibiting IL-6 transcription is one of the mechanisms by which apigenin exhibits its anticancer effects. The potential clinical applications of apigenin in treating esophagus cancer warrant further investigations.

The immunomodulatory peptide bursopentin (BP5) enhances proliferation and induces sIgM expression in DT40 cells.

BACKGROUND: In the recent past, many studies have been focused on extracts of BF and multiple biologically active factors and their effects on humoral immune system in chickens and birds. However, the mechanism of those immunomodulatory peptides on the B lineage cells proliferation and antibody production in chicken is fairly unknown. DT40 cell line, an avian leucosis virus-induced chicken pre-B cell line, expresses immunoglobulin M (IgM) isotype B cell reporter in the plasma membrane. There are many evidences suggesting that DT40 cells are best characterized as a bursal stem cell line. Because of the unique characteristics of DT40 cell line, it has been widely used to observe biological processes of pre-B lymphocyte cell within living cells. METHODS: The chicken B cell line DT40 was cultured in Roswell Park Memorial Institute (RPMI) 1640 medium and cytotoxicity was studied. Also, effect of BP5 on cell proliferation and cell cycle distribution of DT40 cells was studied. Also, the effect of BP5 on sIgM mRNA expression was studied by using real-time PCR. OBJECTIVES: To investigat the effects of Bursopentin (Cys-Lys-Arg-Val-Tyr, BP5) on a chicken promyelocyte cell line DT40, assays of cell proliferation, cell cycle distribution, detection of surface immunoglobulin G (sIgM) mRNA expression and gene microarray analysis were performed. RESULTS: The results showed that BP5 displayed concentration-dependent effects on the proliferation, cell cycle, and sIgM mRNA expression in DT40 cells. And the analysis of expression profiles identified a signature set of 3022 genes (1254 up regulated genes, 1762 down regulated genes), which clearly discriminated the BP5-treated DT40 cells from control with high certainty (P≤0.02). The results of microarray analysis were confirmed by quantitative reverse transcription-polymerase chain reaction for 12 of the differentially expressed genes. CONCLUSION: Theses findings showed the immuno-activity effect of BP5 on B lymphocyte and indicated that BP5 treatment regulated eight signaling pathways, in which Toll-like signaling pathway was the most significant enrichment pathway.

Immunomodulatory roles and functional analysis of pre-B lymphocyte DT40 cells with the bursal-derived BSP-II treatment.

The bursa of Fabricius, the acknowledged central humoral immune organ, is vital to B cell differentiation. However, the regulatory function of the bursal-derived peptide on avian B cell proliferation has not been reported. BSP-II is a recently reported bursal-derived bioactive peptide. In this paper, 75 days-old chicks were twice subcutaneously immunized with BSP-II and inactivated avian influenza virus (AIV, H(9)N(2) strain). It was proved that BSP-II induced a strongly AIV-specific HI antibody production in the immunized chicks. Also, BSP-II could enhance avian pre-B lymphocyte DT40 cell viability. To investigate the global patterns of gene expression in DT40 cells after BSP-II treatment, gene microarray was carried out. It was identified that the differentially expressed genes were involved in various pathways, of which six pathways were associated with signaling transductions, including ErbB signaling, MAPK signaling, Toll-like receptor signaling, Notch signaling, mTOR signaling, and Wnt signaling. Finally, RT-qPCR was used to confirm the microarray expression data. These results indicated the molecular basis of pre-B lymphocyte viability with BSP-II treatment, which provided a potential mechanism of the bursa of Fabricius on pre-B lymphocyte viability, differentiation, and development. These results are valid for the mechanism of the bursa of Fabricius on B lymphocytes development.