Msi1 confers resistance to TRAIL by activating ERK in liver cancer cells

Harnessing TRAIL-Induced Apoptosis Pathway for Cancer Immunotherapy and Associated Challenges

The immune cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has attracted rapidly evolving attention as a cancer treatment modality because of its competence to selectively eliminate tumor cells without instigating toxicity in vivo. TRAIL has revealed encouraging promise in preclinical reports in animal models as a cancer treatment option; however, the foremost constraint of the TRAIL therapy is the advancement of TRAIL resistance through a myriad of mechanisms in tumor cells. Investigations have documented that improvement of the expression of anti-apoptotic proteins and survival or proliferation involved signaling pathways concurrently suppressing the expression of pro-apoptotic proteins along with down-regulation of expression of TRAILR1 and TRAILR2, also known as death receptor 4 and 5 (DR4/5) are reliable for tumor cells resistance to TRAIL. Therefore, it seems that the development of a therapeutic approach for overcoming TRAIL resistance is of paramount importance. Studies currently have shown that combined treatment with anti-tumor agents, ranging from synthetic agents to natural products, and TRAIL could result in induction of apoptosis in TRAIL-resistant cells. Also, human mesenchymal stem/stromal cells (MSCs) engineered to generate and deliver TRAIL can provide both targeted and continued delivery of this apoptosis-inducing cytokine. Similarly, nanoparticle (NPs)-based TRAIL delivery offers novel platforms to defeat barricades to TRAIL therapeutic delivery. In the current review, we will focus on underlying mechanisms contributed to inducing resistance to TRAIL in tumor cells, and also discuss recent findings concerning the therapeutic efficacy of combined treatment of TRAIL with other antitumor compounds, and also TRAIL-delivery using human MSCs and NPs to overcome tumor cells resistance to TRAIL.

Long noncoding RNA LEF1-AS1 acts as a microRNA-10a-5p regulator to enhance MSI1 expression and promote chemoresistance in hepatocellular carcinoma cells through activating AKT signaling pathway

Long noncoding RNAs (lncRNAs) contribute to the development of hepatocellular carcinoma (HCC), which could regulate various HCC biological characteristics. Here, the study seeks to investigate the role of lncRNA LEF1-AS1 in HCC cell chemoresistance by regulating microRNA (miR)-10a-5p and Musashi1 (MSI1). The microarray-based analysis was employed to identify the HCC-related lncRNA-miRNA-gene regulatory network. Expression patterns of LEF1-AS1, miR-10a-5p, and MSI1 in the HCC cell lines, tissues were accessed by means of reverse transcription-quantitative polymerase chain reaction. Next, the interaction among LEF1-AS1, miR-10a-5p, and MSI1 in HCC was accessed by bioinformatics and dual-luciferase reporter gene assay. Then, the cell line resistant to cisplatin was established, which was then treated with sh/oe-lncRNA LEF1-AS1, miR-10a-5p-mimic, and oe/sh-MSI1 vectors alone or in combination. Afterward, the effect of LEF1-AS1, miR-10a-5p, and MSI1 on HCC cell chemoresistance, proliferation, and apoptosis was assessed. At last, in vivo experiments confirmed the role of MSI1 in tumor growth and chemoresistance in HCC. LEF1-AS1 might potentially affect the growth and chemoresistance of HCC cells by regulating miR-10a-5p and MSI1. LEF1-AS1 and MSI1 expression patterns were elevated, while miR-10a-5p was repressed in HCC tissues and cell lines. LEF1-AS1 combined to miR-10a-5p and regulated MSI1, thereby activating the protein kinase B (AKT) signaling pathway. Knockdown of LEF1-AS1 and MSI1 or elevation of miR-10a-5p compromised the proliferation of Huh7 cell line resistant to DDP and promoted its chemosensitivity and apoptosis. At last, these in vitro findings were also confirmed in vivo. Our results unraveled LEF1-AS1 acts as a miR-10a-5p modulator to promote chemoresistance of HCC cells by stimulating MSI1 and activating the AKT signaling pathway, which might provide a novel therapeutic target for HCC.

[Musashi-1 positively regulates growth and proliferation of hepatoma cells in vitro]

OBJECTIVE

To investigate the regulatory role of Musashi-1 (MSI1) in the proliferation and growth of hepatocellular carcinoma (HCC) cells.

METHODS

We examined the expression of MSI1 in HCC and paired adjacent tissues from 24 patients using immunohistochemistry and Western blotting. A MSI1-expressing vector was constructed and stably transfected into HepG2 cells, and short hairpin RNAs (shRNAs) that targeted MSI1 mRNA were ligated into the vector and stably transfected in Huh7 cells. The effects of MSI1 overexpression and silencing on the proliferation, viability and cell cycle of HepG2 cells were investigated using flow cytometry or MTT assay. The expressions of PCNA, cyclin D1, APC and β-catenin in the HCC cells were detected with Western blotting.

RESULTS

MSI1 expression was significantly up-regulated in HCC tissues as compared with that in the adjacent tissues. Overexpression of MSI1 in HepG2 cells resulted in significantly enhanced cell growth (P < 0.01) and significantly reduced G0/G1 phase cells from (58.42±3.18)% to (40.67±1.22)% and increased S phase cells from (28.51± 1.93)% to (40.06±1.92)% (P < 0.01), causing also increases in the expressions of PCNA and Cyclin D1. Knockdown of MSI1 in Huh7 cells obviously inhibited the cell growth and caused cell cycle arrest at the G1/S phase (P < 0.01) with reduced protein expressions of PCNA and cyclin D1. Overexpression of MSI1 in HepG2 cells also down-regulated the expression of APC and up-regulated the expression of β-catenin protein, while MSI1 knockdown caused reverse changes in Huh7 cells.

CONCLUSIONS

MSI1 promotes the progression of HCC through positive modulation of cell growth and cell cycle via the Wnt/β-catenin pathway.

Adipose Tissue-Derived Mesenchymal Stem Cells Suppress Growth of Huh7 Hepatocellular Carcinoma Cells via Interferon (IFN)-β-Mediated JAK/STAT1 Pathway in vitro

Interferon (IFN)-β and/or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) secreted by adipose tissue-derived mesenchymal stem cells (ASCs) have been proposed as key mechanistic factors in anti-cancer efficacy in lung cancer and breast cancer cells, where they act through paracrine signaling. We hypothesized that IFN-β and TRAIL produced by ASCs suppress proliferation of hepatocellular carcinoma cells (HCCs). The present study evaluated the anti-cancer effects of ASCs on HCCs in vitro. We found that indirect co-culture with ASCs diminished growth of Huh7 hepatocellular carcinoma cells with increased protein levels of p53/p21 and phosphorylated STAT1 (pSTAT1), without apoptosis. Treatment with ASC-conditioned medium (ASC-CM) also decreased growth of Huh7 cells through elevated p53/p21 and pSTAT1 signaling. ASC-CM-mediated inhibition of cell growth was neutralized in Huh7 cells treated with anti-IFN-β antibody compared to that in ASC-CM-treated Huh7 cells incubated with an anti-TRAIL antibody. Treatment with JAK1/JAK2 inhibitors recovered inhibition of growth in Huh7 cells incubated in ASC-CM or IFN-β via down-regulation of pSTAT1/p53/p21. However, treatment of IFN-β resulted in no alterations in resistance of Huh7 cells to TRAIL. Our findings suggest that ASCs decrease growth through activated STAT1-mediated p53/p21 by IFN-β, but not TRAIL, in Huh7 cells.

Upregulation of musashi1 increases malignancy of hepatocellular carcinoma via the Wnt/β-catenin signaling pathway and predicts a poor prognosis

Background

Hepatocellular carcinoma (HCC) is a common human malignant cancer due to a high metastatic capacity and the recurrence rate is also high. This study is aim to investigate the role of musashi1 as a potential biomarker for therapy of HCC.

Methods

The mRNA and protein expression levels of musashi1 were detected in HCC samples and cell lines. The malignant properties of HCC cells, including proliferation, invasion and migration were measured by overexpressing or knocking down expression of musashi1. Additionally, the correlation between musashi1 and clinicopathological indexes and prognosis were analyzed. The expression of CD44 was measured and the correlation between CD44 and musashi1 was analyzed.

Results

In vitro cytological experiments demonstrated that musashi1 was elevated in HCC samples and cell lines and this increased expression affected cancer cell viability, migration and invasive capacity by activating of the Wnt/β-catenin signaling pathway. Analysis of clinicopathological characteristics suggested that up-regulation of musashi1 was related to metastasis potential and a poor prognosis. Besides, there was a positive correlation between CD44 and musashi1 expression. Upregulation of musashi1 in malignant liver tumors may have contributed to the maintenance of stem-cell like characteristics of HCC cells.

Conclusions

Upregulation of musashi1 could enhance malignant development of HCC cells and thus might be a novel marker for HCC therapy.

C-terminal truncated HBx reduces doxorubicin cytotoxicity via ABCB1 upregulation in Huh-7 hepatocellular carcinoma cells

Hepatitis B virus (HBV) encoding the HBV x protein (HBx) is a known causative agent of hepatocellular carcinoma (HCC). Its pathogenic activities in HCC include interference with several signaling pathways associated with cell proliferation and apoptosis. Mutant C-terminal-truncated HBx isoforms are frequently found in human HCC and have been shown to enhance proliferation and invasiveness leading to HCC malignancy. We investigated the molecular mechanism of the reduced doxorubicin cytotoxicity by C-terminal truncated HBx. Cells transfected with C-terminal truncated HBx exhibited reduced cytotoxicity to doxorubicin compared to those transfected with full-length HBx. The doxorubicin resistance of cells expressing C-terminal truncated HBx correlated with upregulation of the ATP binding cassette subfamily B member 1(ABCB1) transporter, resulting in the enhanced efflux of doxorubicin. Inhibiting the activity of ABCB1 and silencing ABCB1 expression by small interfering ribonucleic acid (siRNA) increased the cytotoxicity of doxorubicin. These results indicate that elevated ABCB1 expression induced by C-terminal truncation of HBx was responsible for doxorubicin resistance in HCC. Hence, co-treatment with an ABCB1 inhibitor and an anticancer agent may be effective for the treatment of patients with liver cancer containing the C-terminal truncated HBx.

ISG12a and its interaction partner NR4A1 are involved in TRAIL-induced apoptosis in hepatoma cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in cancer cells while sparing normal cells, thereby leading to the development of TRAIL receptor agonists for cancer treatment. However, these agonist-based therapeutics exhibit little clinical benefits due to the lack of biomarkers to predict whether patients are responsive to the treatment, as well as determine the resistance of cancer cells to TRAIL-based agonists. Our previous study has demonstrated that ISG12a enhances TRAIL-induced apoptosis and might serve as a biomarker to predict the TRAIL response. The downstream mechanism by which ISG12a augments TRAIL-induced apoptosis remains to be elucidated. In this study, we found that ISG12a was localized in the mitochondria and nucleus and augmented TRAIL-induced apoptosis through intrinsic apoptotic pathway. In addition, ISG12a interacted with NR4A1 and promoted its nuclear-to-cytoplasm translocation. Upon translocate to cytoplasm, NR4A1 targeted mitochondria and induced Bcl2 conformational change, thereby exposing its BH3 domain. Moreover, TRAIL treatment can induce NR4A1 expression through the activation of NF-κB in TRAIL-resistant Huh7 hepatoma cells. Knockdown of NR4A1 could overcome TRAIL resistance. However, in TRAIL-sensitive LH86 liver cancer cells, TRAIL activated the Jun N-terminal kinases signalling pathway. Overall, these results showed that both ISG12a and its interaction partner NR4A1 are involved in TRAIL-mediated apoptosis in hepatoma cells.

CASC2/miR-24/miR-221 modulates the TRAIL resistance of hepatocellular carcinoma cell through caspase-8/caspase-3

Hepatocellular carcinoma is one of the most common solid tumors in the digestive system. The prognosis of patients with hepatocellular carcinoma is still poor due to the acquisition of multi-drug resistance. TNF Related Apoptosis Inducing Ligand (TRAIL), an attractive anticancer agent, exerts its effect of selectively inducing apoptosis in tumor cells through death receptors and the formation of the downstream death-inducing signaling complex, which activates apical caspases 3/8 and leads to apoptosis. However, hepatocellular carcinoma cells are resistant to TRAIL. Non-coding RNAs, including long non-coding RNAs (lncRNAs) and miRNAs have been regarded as major regulators of normal development and diseases, including cancers. Moreover, lncRNAs and miRNAs have been reported to be associated with multi-drug resistance. In the present study, we investigated the mechanism by which TRAIL resistance of hepatocellular carcinoma is affected from the view of non-coding RNA regulation. We selected and validated candidate miRNAs, miR-24 and miR-221, that regulated caspase 3/8 expression through direct targeting, and thereby affecting TRAIL-induced tumor cell apoptosis TRAIL resistance of hepatocellular carcinoma. In addition, we revealed that CASC2, a well-established tumor suppressive long non-coding RNA, could serve as a "Sponge" of miR-24 and miR-221, thus modulating TRAIL-induced tumor cell apoptosis TRAIL resistance of hepatocellular carcinoma. Taken together, we demonstrated a CASC2/miR-24/miR-221 axis, which can affect the TRAIL resistance of hepatocellular carcinoma through regulating caspase 3/8; through acting as a "Sponge" of miR-24 and miR-221, CASC2 may contribute to improving hepatocellular carcinoma TRAIL resistance, and finally promoting the treatment efficiency of TRAIL-based therapies.

Musashi-1 regulates AKT-derived IL-6 autocrinal/paracrinal malignancy and chemoresistance in glioblastoma

Glioblastoma multiform (GBM) is one of the most lethal human malignant brain tumors with high risks of recurrence and poor treatment outcomes. The RNA-binding protein Musashi-1 (MSI1) is a marker of neural stem/progenitor cells. Recent study showed that high expression level of MSI1 positively correlates with advanced grade of GBM, where MSI1 increases the growth of GBM. Herein, we explore the roles of MSI1 as well as the underlying mechanisms in the regulation of drug resistance and tumorigenesis of GBM cells. Our results demonstrated that overexpression of MSI1 effectively protected GBM cells from drug-induced apoptosis through down-regulating pro-apoptotic genes; whereas inhibition of AKT withdrew the MSI1-induced anti-apoptosis and cell survival. We further showed that MSI1 robustly promoted the secretion of the pro-inflammatory cytokine IL-6, which was governed by AKT activity. Autonomously, the secreted IL-6 enhanced AKT activity in an autocrine/paracrine manner, forming a positive feedback regulatory loop with the MSI1-AKT pathway. Our results conclusively demonstrated a novel drug resistance mechanism in GBM cells that MSI1 inhibits drug-induced apoptosis through AKT/IL6 regulatory circuit. MSI1 regulates both cellular signaling and tumor-microenvironmental cytokine secretion to create an intra- and intercellular niche for GBM to survive from chemo-drug attack.

Pro-survival effects by NF-κB, Akt and ERK(1/2) and anti-apoptosis actions by Six1 disrupt apoptotic functions of TRAIL-Dr4/5 pathway in ovarian cancer

Apoptotic signaling provoked by death receptors, DR4 and DR5, are generally considered to promote cell death and chemosensitivity in multiple cancers, but this view is being thrown into doubt with recent findings that up-regulated DR4 and DR5 in advanced stages of ovarian cancer are associated with the poor prognosis. For this conflict, two reasonable explanations have been proposed: one is that DR4 and DR5 not exclusively mediate apoptotic pathway, but also favor survival signal; another is that apoptotic signals by DR4 and DR5 are disrupted by some regulators. This study identified these two speculations in TRAIL-resistant (SKOV-3ip1 and A2780) or sensitive (OVCAR-3) ovarian cancer cells. Activation of DR4 and DR5 using their specific ligand, TRAIL, activated pro-survival factors including NF-κB, Akt and ERK(1/2) in ovarian cancer SKOV-3ip1 and A2780 cells. Pharmacological inhibition of their activities potentiated TRAIL cytotoxicity, reducing cell viability and increasing apoptosis. Six1, a homeobox transcription factor, had higher expression in SKOV-3ip1 and A2780 cells than in OVCAR-3 cells. Silencing Six1 raised levels of apoptotic factors including cleaved Bid, caspase-8 and caspase-3, and overrode the TRAIL-resistance. Co-treatment with Six1 knockdown and peptidyl O-glycosyltransferase 14 overexpression showed additive effects on apoptosis signal, leading to increased apoptosis in SKOV-3ip1 and A2780 cells. This study demonstrated that pro-survival effects by NF-κB, Akt and ERK(1/2) and anti-apoptosis actions by Six1 disrupt apoptotic functions of TRAIL-Dr4/5 pathway in ovarian cancer, which may explain why up-regulated DR4 and DR5 in ovarian cancer are associated with poor prognosis and low survival ratio of the patients.

Correlation between Polymorphism of TRAIL Gene and Condition of Intervertebral Disc Degeneration

Background

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been suggested to be related with the pathogenesis and progression of osteoarticular degenerations. This study therefore aimed to investigate the relationship between the polymorphism of the TRAIL gene and the pathogenesis and severity of intervertebral disc degeneration (IDD) via detection of serum TRAIL expression levels.

Material/Methods

A total of 100 IDD patients in our hospital were recruited in the experimental group, while another cohort of 100 healthy individuals was employed as the control group. Blood samples collected from all people were quantified for TRAIL level using enzyme-linked immunosorbent assay (ELISA), in addition to allele and genotype frequency analysis via fluorescent PCR for TRAIL gene.

Results

At loci 1525 and 1529 in 3′-untranslated region (UTR) of 5^th exon of TRAIL gene, 3 different genotypes were identified: experimental group had higher frequency of 1525CG/1595CC, 1525G and 1595C alleles, compared to the control group (p<0.05). Patients under Schneiderman grade IV had significantly higher allele frequency compared to those at grade II or III. Serum TRAIL level was also higher in the experimental group compared to the control group, and in grade IV patients compared to grade II or III patients (p<0.05).

Conclusions

The G/C mutation at loci 1525/1595 of TRAIL gene may induce the progression of IDD, as the down-regulation of TRAIL can aggravate the severity of the disease.