Background: Iron metabolism is essential because it plays regulatory roles in various physiological and pathological processes. Disorders of iron metabolism balance are related to various cancers, including hepatocellular carcinoma. Cancer stem-like cells (CSCs) exert critical effects on chemotherapy failure, cancer metastasis, and subsequent disease recurrence and relapse. However, little is known about how iron metabolism affects liver CSCs. Here, we investigated the expression of transferrin receptor 1 (TFR1) and ferroportin (FPN), two iron importers, and an upstream regulator, iron regulatory protein 2 (IRP2), in liver hepatocellular carcinoma (LIHC) and related CSCs.Methods: The expression levels of TFR1, FPN and IRP2 were analysed using the GEPIA database. CSCs were derived from parental LIHC cells cultured in serum-free medium. After TFR1 knockdown, ROS accumulation and malignant behaviours were measured. The CCK-8 assay was performed to detect cell viability after TFR1 knockdown and erastin treatment.Results: TFR1 expression was upregulated in LIHC tissue and CSCs derived from LIHC cell lines, prompting us to investigate the roles of TFR1 in regulating CSCs. Knockdown of TFR1 expression decreased iron accumulation and inhibited malignant behaviour. Knockdown of TFR1 expression decreased reactive oxygen species (ROS) accumulation induced by erastin treatment and maintained mitochondrial function, indicating that TFR1 is critical in regulating erastin-induced cell death in CSCs. Additionally, knockdown of TFR1 expression decreased sphere formation by decreasing iron accumulation in CSCs, indicating a potential role for TFR1 in maintaining stemness.Conclusion: These findings, which revealed TFR1 as a critical regulator of LIHC CSCs in malignant behaviour and stemness that functions by regulating iron accumulation, may have implications to improve therapeutic approaches.

Background: Glioma is the most common and lethal form of brain cancer. It is highly malignant and is often characterized by chemoresistance and radioresistance, which are thought to mainly result from hypoxic microenvironments. Various tumour-promoting and tumour-suppressing microRNAs (miRNAs) have been identified in gliomas; however, it is still largely unknown how miRNAs are modified by hypoxia and subsequently affect glioma. In this study, we examined the expression of miR-210-3p, a well-characterized miRNA that responds to hypoxia in glioma cell lines. Methods: The expressions of miR-9 and miR-210-3p were analysed by using qPCR. Cell viability was measured by performing CCK-8 after eechinomycin treatment or introduction of miR-210 for 24 or 48 h. The correlation of HIF-1α expression with TGF-β were analysed using the REMBRANDT database. The biomarkers of EMT, including E-cadherin, N-cadherin and Vimentin, were detected by western blot. Apoptotic cell death was measured by performing Annexin V-FITC/PI double staining followed by flow cytometry. Results: We found that miR-210-3p was induced by a mechanism dependent on the hypoxia-induced transcriptional activity of HIF-1α. Then we established a positive association between the HIF-1α and TGF-β expression levels, and miR-210-3p upregulation induced TGF-β expression, indicating that hypoxia-induced HIF-1α activity upregulated TGF-β via miR-210-3p upregulation. Hypoxia-induced miR-210-3p activity was found to promote EMT by upregulating TGF-β, which subsequently enhanced the invasive ability in U87-MG cells. We further confirmed that miR-210-3p induced chemoresistance to TMZ in U87-MG cells via TGF-β upregulation under hypoxic conditions. Conclusion: These results help to reveal the potential regulatory mechanisms of hypoxia-induced miR-210-3p expression that affect malignant behaviors and chemoresistance via TGF-β upregulation in glioma cells.

Growth arrest‑specific 5 (GAS5) is a known tumor suppressor which negatively regulates cell survival and malignancy in several cancer cell types. The present study aimed to establish the correlation between GAS5 and unc‑51 like autophagy activating kinase (ULK)1/2, two key regulators of autophagy initiation in breast cancer (BC). To address this, expression levels of these genes were quantitively analyzed in BC clinical samples by performing reverse transcription‑quantitative PCR. GAS5 was downregulated in BC clinical samples compared with adjacent samples and was positively correlated with ULK1/2. Detection methods including cell cycle analysis, annexin V‑FITC/PI double staining and flow cytometry analysis, Transwell cell invasion assay, transfection and western blotting were used for BC cells. In MCF‑7 cells, it was also observed that overexpression of GAS5 upregulated ULK1/2 protein levels without disturbing other autophagy initiation‑associated proteins and inhibited cell proliferation, invasion and tumor formation. These effects were reversed by blocking autophagy with 3‑methyladenine (3‑MA). These results demonstrated that the suppressive effects of overexpressed GAS5 were mediated via autophagy induction, at least in part. Overexpression of GAS5 induced chemoresistance to cisplatin, which was not reversed by 3‑MA‑mediated inhibition of autophagy, indicating that GAS5 promotes chemosensitivity in an autophagy‑independent manner. Collectively, these results indicated that GAS5 contributes to the pathogenesis of BC potentially by promoting autophagy. However, the mechanism by which GAS5 functions as a tumor suppressor in an autophagy‑independent manner remains unknown.

Long non‑coding RNAs (lncRNAs) are known to be involved in the processes of tumourigenesis and malignant behaviours in many types of cancer, including acute myeloid leukaemia (AML). Accumulating evidence has revealed that novel lncRNAs exerted critical roles in these processes. In the present study, we investigated the effects of lncRNA linc00239 (NR_026774.1), which is 662 φnucleotides (nt) in length and was found to be upregulated in AML patients, on malignant behaviours and chemosensitivity in AML cells, including KG‑1 and HL‑60. linc00239 expression was detected in KG‑1 and HL‑60 cells by quantitative PCR and northern blotting, and it was found that linc00239 is detectable by both of these assays. After knockdown or overexpression of linc00239 in AML cells, the results revealed that the presence of linc00239 promoted proliferation, colony formation and migration ability. Furthermore, the presence of linc00239 increased chemoresistance to doxorubicin in AML cells partially by preventing doxorubicin‑induced apoptotic cell death. It was also determined that the presence of linc00239 was related to activation of the phosphatidylinositol 3‑kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. Inhibition of PI3K/Akt/mTOR using 1 µM NVP‑BEZ235 (BEZ) abolished the inhibitory effect of linc00239 on chemosensitivity and the preventative effect on doxorubicin‑induced cell death. Collectively, our data revealed that linc00239 is a novel tumour promoter in AML cells and indicated that it is a potential therapeutic target.