AEG-1 is associated with hypoxia-induced hepatocellular carcinoma chemoresistance via regulating PI3K/AKT/HIF-1alpha/MDR-1 pathway

IL-6/STAT3 Is a Promising Therapeutic Target for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor of which the occurrence and development, the tumorigenicity of HCC is involving in multistep and multifactor interactions. Interleukin-6 (IL-6), a multifunctional inflammatory cytokine, has increased expression in HCC patients and is closely related to the occurrence of HCC and prognosis. IL-6 plays a role by binding to the IL-6 receptor (IL-6R) and then triggering the Janus kinase (JAK) associated with the receptor, stimulating phosphorylation and activating signal transducer and activator of transcription 3 (STAT3) to initiate downstream signals, participating in the processes of anti-apoptosis, angiogenesis, proliferation, invasion, metastasis, and drug resistance of cancer cells. IL-6/STAT3 signal axes elicit an immunosuppressive in tumor microenvironment, it is important to therapy HCC by blocking the IL-6/STAT3 signaling pathway. Recent, some inhibitors of IL-6/STAT3 have been development, such as S31-201 or IL-6 neutralizing monoclonal antibody (IL-6 mAb), Madindoline A (Inhibits the dimerization of IL-6/IL-6R/gpl30 trimeric complexes), C188-9 and Curcumin (Inhibits STAT3 phosphorylation), etc. for treatment of cancers. Overall, consideration of the IL-6/STAT3 signaling pathway, and its role in the carcinogenesis and progression of HCC will contribute to the development of potential drugs for targeting treatment of liver cancer.

Phenylethanol glycosides from Herba Cistanche improve the hypoxic tumor microenvironment and enhance the effects of oxaliplatin via the HIF‑1α signaling pathway

Liver cancer is one of the most common types of malignant tumor, and is characterized by high malignancy, rapid progression, high morbidity and mortality. Oxaliplatin (OXA) has been reported to have marked efficiency against advanced liver cancer with tolerable toxicity. In solid tumors, the hypoxic microenvironment promotes epithelial‑mesenchymal transition (EMT), which can also induce drug resistance of liver cancer to platinum drugs. Herba Cistanche (Cistanche tubulosa) has been frequently used in traditional Chinese medicine and the phenylethanol glycosides from Herba Cistanche (CPhGs) are the major active components. The present study aimed to investigate the effects of CPhGs on viability, apoptosis, migration and invasion of liver cancer cells. HepG2 liver cancer cells were divided into the control, DMSO, CoCl₂, OXA, OXA + CoCl₂ and CPhGs + OXA + CoCl₂ groups. Subsequently, reverse transcription‑quantitative PCR and western blot analysis were performed to determine the expression levels of hypoxia‑inducible factor 1α (HIF‑1α), lysyl oxidase‑like 2 (LOXL2) and EMT‑related genes and proteins (i.e., E‑cadherin and Twist), in order to investigate the effects of CPhGs on liver cancer. The results demonstrated that CPhGs could enhance the effects of OXA on liver cancer, and inhibit the migration, invasion and apoptotic rate of liver cancer cells. Additionally, CPhGs treatment effectively induced downregulation of HIF‑1α, LOXL2 and Twist, and upregulation of E‑cadherin. The present findings indicated that CPhGs triggered a significant increase in sensitivity to OXA and suppression of hypoxia‑induced EMT in liver cancer by inhibiting the HIF‑1α signaling pathway. Therefore, CPhGs may be considered an effective platinum drug sensitizer, which could improve chemotherapeutic efficacy in patients with liver cancer.

LY‑294002 enhances the chemosensitivity of liver cancer to oxaliplatin by blocking the PI3K/AKT/HIF‑1α pathway

Liver cancer remains one of the leading causes of cancer deaths worldwide. The therapeutic effect of oxaliplatin on liver cancer is often limited by acquired resistance of the cancer cells. Abnormal activation of the PI3K/AKT pathway plays an important role in the acquired resistance of oxaliplatin. The present study investigated the effects of the PI3K inhibitor LY-294002 and AKT inhibitor MK2206 on the chemosensitivity of oxaliplatin-resistant liver cancer cells and the molecular mechanism involved. An oxaliplatin-resistant liver cancer cell line HepG2^R was developed. MTT assay, clone formation experiments, flow cytometry and Annexin V-FITC/PI staining were used to determine the proliferation, cycle and apoptosis of HepG2^R cells when oxaliplatin was combined with LY-294002 or MK2206 treatment. The effects of LY-294002 and MK-2206 on the abnormal activation of PI3K/AKT pathway and hypoxia inducible factor (HIF)-1α protein level in HepG2^R cells were detected using western blotting. The results indicated that the PI3K/AKT pathway is stably activated in HepG2^R cells. Compared with the AKT inhibitor MK2206, the PI3K inhibitor LY-294002 more effectively downregulated the phosphorylation levels of p85, p110α, p110β, p110γ and AKT in the PI3K/AKT pathway in HepG2^R cells, and more effectively inhibited the proliferation of the cells. LY-294002 enhanced the chemotherapy sensitivity of HepG2^R cells to oxaliplatin by inducing G₀/G₁ phase arrest and increasing the proportion of apoptotic cells. In addition, LY-294002 reduced the level of HIF-1α, which is highly expressed in HepG2^R cells. It was concluded that LY-294002 enhanced the chemosensitivity of liver cancer cells to oxaliplatin by inhibiting the PI3K/AKT signaling pathway, which may be related to the inhibition of HIF-1α expression. These findings may have clinical significance for the treatment of oxaliplatin-resistant liver cancer.

Multifunctional Role of Astrocyte Elevated Gene-1 (AEG-1) in Cancer: Focus on Drug Resistance

Simple Summary

Chemotherapy is a major mode of treatment for cancers. However, cancer cells adapt to survive in stressful conditions and in many cases, they are inherently resistant to chemotherapy. Additionally, after initial response to chemotherapy, the surviving cancer cells acquire new alterations making them chemoresistant. Genes that help adapt the cancer cells to cope with stress often contribute to chemoresistance and one such gene is Astrocyte elevated gene-1 (AEG-1). AEG-1 levels are increased in all cancers studied to date and AEG-1 contributes to the development of highly aggressive, metastatic cancers. In this review, we provide a comprehensive description of the mechanism by which AEG-1 augments tumor development with special focus on its ability to regulate chemoresistance. We also discuss potential ways to inhibit AEG-1 to overcome chemoresistance.

Abstract

Cancer development results from the acquisition of numerous genetic and epigenetic alterations in cancer cells themselves, as well as continuous changes in their microenvironment. The plasticity of cancer cells allows them to continuously adapt to selective pressures brought forth by exogenous environmental stresses, the internal milieu of the tumor and cancer treatment itself. Resistance to treatment, either inherent or acquired after the commencement of treatment, is a major obstacle an oncologist confronts in an endeavor to efficiently manage the disease. Resistance to chemotherapy, chemoresistance, is an important hallmark of aggressive cancers, and driver oncogene-induced signaling pathways and molecular abnormalities create the platform for chemoresistance. The oncogene Astrocyte elevated gene-1/Metadherin (AEG-1/MTDH) is overexpressed in a diverse array of cancers, and its overexpression promotes all the hallmarks of cancer, such as proliferation, invasion, metastasis, angiogenesis and chemoresistance. The present review provides a comprehensive description of the molecular mechanism by which AEG-1 promotes tumorigenesis, with a special emphasis on its ability to regulate chemoresistance.

Sphingosine kinase 1 contributes to doxorubicin resistance and glycolysis in osteosarcoma

Osteosarcoma (OS) is one of the most common and aggressive malignancies in children and adolescents worldwide. Sphingosine kinase 1 (SphK1) has recently been reported to serve a role in OS progression. The present study aimed to investigate the role of SphK1 in the development of chemoresistance and glycolysis in OS cell lines. SphK1 expression levels in OS cell lines (U2OS, MG63 and SaoS2) were analyzed using western blotting and reverse transcription-quantitative PCR (RT-qPCR). A cell survival assay was conducted to determine doxorubicin-resistance in OS cells, and glycolysis was also evaluated. SphK1 expression was increased in the U2OS and SaoS2 cell lines, and both cell lines were more resistant to doxorubicin when compared with the MG63 cell line. SphK1 knockdown or overexpression altered doxorubicin resistance and the viability of OS cell lines. In addition, hypoxia inducible factor-1α (HIF-1α) expression was positively associated with SphK1 expression, and partly mediated SphK1-induced effects on doxorubicin resistance and glycolysis. The present study suggested that SphK1 participated in the development of doxorubicin resistance and contributed to glycolysis in OS cells by regulating HIF-1α expression. However, further studies investigating the application of SphK1 associated therapies for patients with OS are required.

Long noncoding RNA lncARSR confers resistance to Adriamycin and promotes osteosarcoma progression

One of the significant challenges for chemotherapy is the appearance of resistance to compounds. Although several signaling pathways have been implicated in the development of Adriamycin (ADM) resistance, mechanisms involved in ADM-resistant osteosarcoma progression remain unknown. The present study attempted to illustrate the role of long noncoding RNA ARSR (lncARSR) in the development of adapted ADM resistance. We found lncARSR overexpressed in the Adriamycin-resistant cell lines U2OS/ADM and MG63/ADM, accompanied with acquired multidrug resistance against to paclitaxel and cisplatin. Overexpression of lncARSR triggered rhodamine 123 efflux and survival, as well as the migration of Adriamycin-resistant cells. Inversely, the depletion of lncARSR promoted rhodamine 123 retention and apoptosis, while reducing the motility of ADM-resistant cells. Further investigation revealed that the upregulation of lncARSR enhanced multidrug resistance-associated protein-1 (MRP1), apoptosis inhibitor Survivin, and matrix metalloproteinase-2 (MMP2) through activating AKT. The reduction of lncARSR overcame the resistance to ADM in U2OS/ADM mouse model. The current study gained novel evidence for understanding the mechanisms underlying adaptive ADM resistance and provided rationales to improve clinical outcomes of refractory osteosarcoma.

Long non-coding RNA GAS5 is critical for maintaining stemness and induces chemoresistance in cancer stem-like cells derived from HCT116

Long non-coding RNAs (lncRNAs) are recognized as critical regulators of self-renewal in human cancer stem-like cells (CSCs), which are a subpopulation of cancer cells primarily responsible for the malignant features of cancer. However, most CSC-related lncRNAs remain unidentified. The results of the present study suggested that growth-arrest-specific transcript 5 (GAS5), a tumor suppressor, exhibited increased expression and was associated with malignant features in human colorectal cancer cell HCT116-derived CSCs. Phenotypic analysis indicated that GAS5 knockdown by specific siRNA significantly decreased CSC self-renewal capacity, proliferation and migration. Moreover, GAS5 knockdown sensitized CSCs to the chemotherapeutic agents 5-fluorouracil and doxorubicin by inducing apoptosis detected by Annexin V-FITC/PI double staining. Inhibition of Nodal growth differentiation factor (NODAL) signaling, which has been reported to be protected by GAS5, presented similar chemosensitivity effects to the GAS5 knockdown results. The present study also assessed the effects of GAS5 overexpression on HCT116 cells, and revealed that overexpression of GAS5 sensitized HCT116 cells to chemotherapeutic agents, which is the opposite of the effect observed in CSCs derived from HCT116 cells. Therefore, it was hypothesized that GAS5 may function as a critical factor for maintaining stemness and that it may exert protective effects on CSCs in a NODAL-dependent manner. Collectively, the results of the present study indicate that GAS5 may be a promising therapeutic target for overcoming malignant features and chemoresistance in colorectal cancer cells.

Triptonide inhibits metastasis potential of thyroid cancer cells via astrocyte elevated gene-1

Background

Triptonide (TN) was recently proved to have anti-tumor effects. The current study explored whether TN inhibited thyroid cancer and the possible underlying mechanism.

Methods

MDA-T68 and BCPAP cells were treated by TN. Cell viability, migration and invasion rate were detected by MTT and Transwell. Protein expressions were determined by Western blot and mRNA expressions were detected by Real-time Quantitative PCR (qPCR).

Results

TN at the concentration higher than 50 nmol/L inhibited cell viability, migration and invasion of MDA-T68 and BCPAP cells, and astrocyte elevated gene (AEG-1) expression, was decreased by TN at the concentration higher than 50 nmol/L. Furthermore, AEG-1 overexpression inhibited cell viability, migration and invasion capacity of MDA-T68 and BCPAP cells, while TN reduced AEG-1 expression, and weaken the effect of AEG-1 overexpression on cell viability, migration and invasion capacities. Moreover, TN depressed the increase of matrix metalloproteinase (MMP) 2, MMP9 and N-cadherin expressions caused by AEG-1 overexpression. Meanwhile, E-cadherin expression reduced by AEG-1 overexpression was increased by TN.

Conclusions

TN could inhibit the metastasis potential of thyroid cancer cells through inhibiting the expression of AEG-1. Our findings reveal the mechanism of TN in the treatment of thyroid cancer, which should be further explored in the study of thyroid cancer.

Keywords

Triptonide; metastasis; thyroid cancer; regulation; drug monomer

MiR-145: a potential biomarker of cancer migration and invasion

MircoRNAs (miRNAs) are a diverse family of highly-conserved small non-coding RNAs, which range from approximately 18 to 25 nucleotides in size. They regulate gene expression transcriptionally or post-transcriptionally via binding to the 3'-untranslated region (3'-UTR) of target message RNAs (mRNAs). MiRNAs have emerged as molecular regulators that participate in physiological and pathological processes of diverse malignancies. Among them, miRNA-145 (miR-145) played a profound role in tumorigenesis and progression of various neoplasms. In this review, we summarized the recent findings regarding miR-145, to elucidate its functional roles in cell invasion and migration of diverse human malignancies, and considered it a potential biomarker for cancer diagnosis, screening, and prognosis.

Molecular mechanisms of TUG1 in the proliferation, apoptosis, migration and invasion of cancer cells

Long non-coding RNAs (lncRNAs) are RNA sequences >200 nucleotides in length that have no protein-coding capacity. lncRNAs serve key roles in multiple biological processes, such as tumorigenesis and tumor progression. Taurine upregulated 1 (TUG1) is a novel lncRNA that has been associated with human cancer. TUG1 has attracted increasing attention in recent years and has been documented to be abnormally expressed in different types of cancer. Numerous studies indicate that TUG1 may be significantly associated with tumor development and cell metabolism by regulating cell proliferation, invasion, metastasis, apoptosis, differentiation and drug resistance. TUG1 exerts its function via recruiting specific RNA-binding proteins, promoting target gene expression, influencing tumor angiogenesis and by functioning as a competing endogenous RNA (ceRNA). An increasing number of studies have demonstrated that ceRNAs serve a role in cancer development. TUG1 is considered to be a biomarker or a novel therapeutic target for the diagnosis and prognosis of different cancer types. The present review focuses on recent developments in the major underlying molecular mechanisms of TUG1 in cancer, including its role in cell proliferation, apoptosis, migration, invasion and drug resistance. Also discussed in the present review is the current knowledge regarding the regulation of TUG1.

[Calcium channel blocker diltizem transiently inhibits migration and up-regulates metadherin expression in hepatocellular carcinoma cells in vitro]

OBJECTIVE

To investigate the effect of calcium channel blocker diltizem in reversing multi-drug resistance (MDR) and on metadherin expression in hepatocellular carcinoma cells and explore the molecular mechanism.

METHODS

Hepatocellular carcinoma MHCC97H and 7402 cells were treated with diltiazem hydrochloride, a calcium channel blocker (0, 25, 50, 100, 200, and 400 μmol/L), for 12, 24, or 48 h. Wound healing assay was employed to assess the changes in the mobility and migration of the cells following the treatments, and the changes in the expression levels of metadherin mRNA and protein and P-gp protein were determined using RT-PCR and immunocytochemistry.

RESULTS

Diltiazem hydrochloride could transiently inhibit the migration and movement of MHCC97H and 7402 cells in vitro in a time-and concentration-dependent manner (P < 0.05). Diltiazem hydrochloride at different concentrations also transiently up-regulated the expressions of metadherin mRNA and protein but did not inhibit the expression of P-gp protein in MHCC97H and 7402 cells.

CONCLUSIONS

Calcium channel blocker can transiently inhibit the migration of hepatocellular carcinoma cells in vitro and up-regulate the expression of metadherin mRNA and protein through a feedback mechanism, suggesting the potential risk of calcium channel blockers for promoting tumor progression during the treatment of malignant tumors.

AEG-1 is involved in hypoxia-induced autophagy and decreases chemosensitivity in T-cell lymphoma

Background

This study was to examine the link between astrocyte elevated gene-1 (AEG-1) and hypoxia induced-chemoresistance in T-cell non-Hodgkin’s lymphoma (T-NHL), as well as the underlying molecular mechanisms.

Methods

Expression of AEG-1, LC3-II, and Beclin-1 were initially examined in human T-NHL tissues (n = 30) and normal lymph node tissues (n = 16) using western blot, real-time PCR and immunohistochemistry. Western blot was also performed to analyze the expression of AEG-1, LC3-II, and Beclin-1 in T-NHL cells (Hut-78 and Jurkat cells) under normoxia and hypoxia. Additionally, the proliferation and apoptosis of Hut-78 cells exposed to different concentration of Adriamycin (ADM) in normoxia and hypoxia were evaluated by MTT and Annexin-V FITC/PI staining assay. Finally, the effects of AEG-1 on Hut-78 cells exposed to ADM in hypoxia were assessed by MTT and Annexin-V FITC/PI staining assay, and 3-MA (autophagy inhibitor) was further used to determine the underlying mechanism.

Results

AEG-1, LC3-II and Beclin-1 expression were significantly increased in T-NHL tissues compared with normal tissues. Incubation of Hut-78 and Jurkat cells in hypoxia obviously increased AEG-1, LC3-II and Beclin-1 expression. Hypoxia induced proliferation and reduced apoptosis of Hut-78 cells exposed to ADM. AEG-1 overexpression further increased proliferation and decreased apoptosis of Hut-78 cells exposed to ADM in hypoxia. Moreover, overexpression of AEG-1 significantly inversed 3-MA induced-changes in cell proliferation and apoptosis of Hut-78 cells exposed to ADM in hypoxia.

Conclusions

This study suggested that AEG-1 is associated with hypoxia-induced T-NHL chemoresistance via regulating autophagy, uncovering a novel target against hypoxia-induced T-NHL chemoresistance.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0033-6) contains supplementary material, which is available to authorized users.

Long Noncoding RNA Taurine-Upregulated Gene1 (TUG1) Promotes Tumor Growth and Metastasis Through TUG1/Mir-129-5p/Astrocyte-Elevated Gene-1 (AEG-1) Axis in Malignant Melanoma

BACKGROUND Malignant melanoma is a class of malignant tumors derived from melanocytes. lncRNAs have been considered as pro-/anti-tumor factors in progression of cancers. The function of lncRNA TUG1 on growth of melanoma was investigated in this study. MATERIAL AND METHODS The TUG1 and miR-129-5p expression were examined via qRT-PCR. The protein expression was investigated by Western blotting assay. Luciferase reporter assay was used to assess if lncRNA TUG1 can bind to miR-129-5p and if miR-129-5p can target AEG1 mRNA. CCK-8 and apoptosis assay were used to detect cell growth and apoptosis. The metastasis of melanoma cells was detected by wound-healing and Transwell assays. The effects of TUG1 on growth of melanoma in vivo and cell chemoresistance were investigated via xenograft animal experiment and CCK-8 assay. RESULTS The expression of TUG1 and AEG1 was elevated and the miR-129-5p level was decreased in melanoma specimens and cell lines. Downregulation of either TUG1 or AEG1 suppressed cell growth and metastasis. miR-129-5p can bind directly to AEG1 and TUG1 can directly sponge miR-129-5p. Inhibition of TUG1 expression suppressed the expression of Bcl-2, MMP-9, and cyclin D1, and raised the level of cleaved caspase3 by modulating AEG1 level in melanoma cells. Inhibition of TUG1 reduced the growth of tumors in vivo and improved the chemosensitivity of A375 cells to cisplatin and 5-FU. CONCLUSIONS Reduction of TUG1 level suppressed cell growth and metastasis by regulating AEG1 expression mediated by targeting miR-129-5p. Suppression of lnc TUG1 may be a promising therapeutic strategy in the treatment of malignant melanoma.