Expression Of Mda-7 Research Articles

Uncoupling proteins: are they involved in vitamin D3 protective effect against high-fat diet-induced cardiac apoptosis in rats?

This study aimed to assess the impact of high-fat diet (HFD) and vitamin D3 supplementation on cardiac apoptosis, inflammation, oxidative stress, and cardiac uncoupling proteins (UCPs) 2&3 expression. Forty rats were fed either (45%) or (10%) fat diet with or without vitamin D3 (500 U/kg/day) for 6 months, then cardiac tissue expression of Bax, Bcl2, Fas, Fas-L (markers for apoptotic pathways), TNF-α, MDA7, GPX1 (inflammatory and oxidative markers) and UCP 2&3 were assessed. Results revealed the enhancement of intrinsic and extrinsic cardiomyocyte apoptosis cascades and increased inflammatory and oxidative burdens on the heart in HFD rats. Downregulation of UCP2 and upregulation of UCP3 gene expression at 6 months. After vitamin D3 supplementation with HFD, cardiac apoptotic, inflammatory and oxidative markers were mitigated and expression of UCP3 was downregulated and UCP2 was upregulated. This work highlights the novel cardioprotective effect of vitamin D3 in the experimental model of HFD feeding through the downregulation of UCP3.

Effects of melanoma differentiation associated gene-7 (MDA-7/IL-24) on apoptosis of liver cancer cells via regulating the expression of B-cell lymphoma-2.

The present study investigated the mechanism of selective killing of liver cancer cells of melanoma differentiation associated gene-7 (MDA-7, also called IL-24α) in order to provide a theoretical basis for gene therapy of liver cancer. A recombinant eukaryotic expression vector (pcDNA3-MDA-7) containing human MDA-7 gene was constructed, which was then delivered to liver cancer cell line HepG2 and normal liver cell line L02. The positive cell clone was screened by G418. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to confirm the occurrence of MDA-7 transcription in the transfected cells. The protein expression of MDA-7 was determined by western blot analysis. The effects of MDA-7 on liver cancer cell proliferation and apoptosis were investigated through MTT assay and flow cytometry by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double-staining. The mitochondrial protein was extracted from the normal liver cell line L02 and liver cancer cell line HepG2 at 3 day post-culture, in which the alterations of anti-apoptotic B-cell lymphoma-2 (Bcl-2), pro-apoptotic Bcl-2 associated X protein (Bax), mitochondria-released cytochrome c and caspase 9 were determined by western blot analysis. pcDNA3-MDA-7 mediated the expression of foreign gene MDA-7 in HepG2 and L02 cells. MDA-7 promoted liver cancer cell apoptosis and inhibited cell proliferation; while no effect was exerted on normal liver cells, as determined by the MTT assay and flow cytometry. Relative to the L02 cells, the protein expression of Bcl-2 was downregulated in the HepG2 cells, while that of Bax, cytochrome c and caspase 9 were upregulated. In the study, the eukaryotic expression vector pcDNA3-MDA-7 was successfully constructed, it can mediate the expression of MDA-7 in human liver cancer cells and normal liver cells and inhibits the proliferation of human liver cancer cells through the restored expression of mitochondrial pro-apoptotic Bcl-2.

The clinical significance of Mda-7/IL-24 and C-myb expression in tumor tissues of patients with diffuse large B cell lymphoma.

Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma in adults. Mda-7/IL-24 had been identified as a differentiation inducer of B phenotype lymphoma cells. Previous studies have revealed that knockdown of C-myb also leads to the terminal differentiation of B cell lymphoma. The aim of the present study was to investigate the association between the expression of Mda-7/IL-24 and C-myb, and their prognostic significance for DLBCL patients. The tumor tissues were collected from 72 cases of DLBCL patients and detected with reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry assays. The results showed that, the expression of Mda-7/IL-24 mRNA and protein was lower while the expression of C-myb was higher in DLBCL tissues, compared with the specimens of normal lymph node tissues. Furthermore, C-myb expression was negatively correlated with Mda-7/IL-24 expression at mRNA and protein levels in DLBCL tissues. The expression of Mda-7/IL-24 and C-myb in DLBCL tissues was associated with some clinicopathological parameters such as clinical stage, infiltration in bone marrow, Ki67 expression level in the tumor tissues and overall survival rates. These results indicated that low expression of Mda-7/IL-24, along with high expression of C-myb, are predictor for poor prognosis of DLBCL patients, suggesting that Mda-7/IL-24 and C-myb may be potential targets for clinical treatment of DLBCL.

Low expression of Mda-7/IL-24 and high expression of C-myb in tumour tissues are predictors of poor prognosis for Burkitt lymphoma patients

ABSTRACTObjectivesBurkitt lymphoma is one of the most common types of haematopoietic malignancy in children and adolescents. Mda-7/IL-24 had been identified as a differentiation inducer of Burkitt lymphoma cells. Previous studies have revealed that knockdown of C-myb can also lead to the terminal differentiation of Burkitt lymphoma cells. The aim of the present study was to investigate the correlation between the expression of Mda-7/IL-24 and C-myb, as well as their prognostic significance, for Burkitt lymphoma patients.MethodsThe tumour tissues were collected from 59 cases of Burkitt lymphoma patients and detected with Western blotting and immunohistochemistry.ResultsThe results showed that the expression of Mda-7/IL-24 was lower, whereas the expression of C-myb was higher in Burkitt lymphoma tissues compared to specimens of normal lymph node tissues. Furthermore, C-myb expression was negatively correlated with Mda-7/IL-24 expression at the protein level in Burkitt lymphoma tissues and cell lines. Both the expression of Mda-7/IL-24 and C-myb in Burkitt lymphoma tissues was associated with some clinicopathological parameters, such as clinical stage, infiltration in the bone marrow, Ki67 and overall survival rates.ConclusionThese results indicated that low expression of Mda-7/IL-24 along with high expression of C-myb are predictors for poor prognosis of Burkitt lymphoma patients; this outcome suggests that Mda-7/IL-24 and C-myb might be potential targets for clinical treatment of Burkitt lymphoma.Abbreviations: Mda-7/IL-24: melanoma differentiation associated gene7/interleukin 24; FCM: flow cytometry; Ecog: Eastern Cooperative Oncology Group; IPI: International lymphoma prognosis index

Mda-7/IL-24 Mediates Cancer Cell-Specific Death via Regulation of miR-221 and the Beclin-1 Axis.

Melanoma differentiation-associated gene-7/IL-24 (mda-7/IL-24) displays broad-spectrum anticancer activity in vitro, in vivo in preclinical animal models, and in a phase I/II clinical trial in patients with advanced cancers without harming normal cells or tissues. Here we demonstrate that mda-7/IL-24 regulates a specific subset of miRNAs, including cancer-associated miR-221. Either ectopic expression of mda-7/IL-24 or treatment with recombinant His-MDA-7 protein resulted in downregulation of miR-221 and upregulation of p27 and PUMA in a panel of cancer cells, culminating in cell death. Mda-7/IL-24-induced cancer cell death was dependent on reactive oxygen species induction and was rescued by overexpression of miR-221. Beclin-1 was identified as a new transcriptional target of miR-221, and mda-7/IL-24 regulated autophagy through a miR-221/beclin-1 feedback loop. In a human breast cancer xenograft model, miR-221-overexpressing MDA-MB-231 clones were more aggressive and resistant to mda-7/IL-24-mediated cell death than parental clones. This is the first demonstration that mda-7/IL-24 directly regulates miRNA expression in cancer cells and highlights the novelty of the mda-7/IL-24-miR-221-beclin-1 loop in mediating cancer cell-specific death. Cancer Res; 77(4); 949-59. ©2016 AACR.

MDA7 combined with targeted attenuated Salmonella vector SL7207/pBud-VP3 inhibited growth of gastric cancer cells.

To investigate the therapeutic effect of MDA7 combined with apoptin targeted attenuated Salmonella typhimurium vector SL7207/pBud-VP3 on gastric cancer cells. MDA7 was inserted into pBud-VP3 using molecular cloning technology to obtain the eukaryotic expression plasmid pBud-VP3-MDA7 and it was transformed into attenuated Salmonella typhimurium SL7207 by high voltage electroporation to obtain SL7207/pBud-VP3-MDA7. Mice bearing a sarcoma of gastric cancer cells were treated with SL7207/pBud-VP3-MDA7 and the growth-suppressing effect was assessed by measurement of tumor volume. Western blot was used to identify the MDA7 expression products. IL-6, INF-γ, TNF-α and caspase-3, VEGF in tumor tissue were detected by RT-PCR and immunohistochemistry. SL7207/pBud-VP3-MDA7 was successfully constructed and expression of the protein MDA7 was identified in tumor tissue. SL7207/pBud-VP3-MDA7 significantly caused tumor inhibition and regression (p<0.05). The level of expression of cytokines IL-6, INF-γ, TNF-α in tumor tissue was significantly higher than in the other groups (p<0.05). The expression of caspase-3 was up-regulated and VEGF was down-regulated (p<0.05). This study shows that SL7207/pBud-VP3-MDA7 has inhibitory effect on the growth of gastric cancer cells. The mechanism involved is related to the promotion of tumor apoptosis, immunity regulation and inhibition of tumor blood vessels.

Abstract 3508: The RNA-binding protein CELF1 regulates the tumor suppressive protein IL-24/mda-7 expression in oral squamous cell carcinoma

Abstract The majority of oral squamous cell carcinoma (OSCC) patients are diagnosed at an advanced disease stage and the overall 5-year survival rate, surprisingly, has not changed dramatically over the past several decades. Therefore, identification and subsequent characterization of new molecular determinants of OSCC, may aid in the discovery of novel targets capable of predicting patient treatment response and disease prognosis. Co- and post-transcriptional gene expression plays a crucial role in disease development. RNA binding proteins (RBPs) are critical regulators of messenger RNA (mRNA) fate within mammalian cells. The RBP CELF1 associates with GU-rich element (GRE) containing mRNAs and post transcriptionally regulates mRNA stability, translation and pre-mRNA alternative splicing. Our previous studies demonstrated that the protein levels of CELF1, increased as HNSCC disease progressed from Stage I-IV. In addition, reduction of CELF1 in oral cancer cells promoted programmed cell death and decreased tumor burden in a xenograft mouse model. In an effort to understand the underlying mechanism employed by CELF1 to promote anti-tumor activity, we utilized genomic techniques to identify CELF1 mRNA targets in oral cancer cells. Interestingly, the gene IL-24/mda-7 was one of the top aberrantly expressed mRNAs identified as a function of CELF1 levels in oral cancer cells. Interleukin -24 also known as melanoma differentiation associated gene-7 (IL-24/mda-7) is a member of the IL-10 related family of cytokines. IL-24 protein expression is absent in most cancers and forced expression of IL-24 using an adenoviral vector enhances tumor cell-specific apoptosis. Although the mechanism of IL-24 induced cell death has been studied for several cancers, the role of IL-24 in HNSCC is not well known. In addition, the regulatory mechanisms controlling IL-24 expression in cancer are not well studied. Here, we show that IL-24 mRNA is overexpressed in HNSCC tissues compared to normal specimens. Furthermore, utilizing a mouse model of oral carcinogenesis we determined that IL-24 mRNA levels are enhanced in hyperplastic/dysplastic and oral squamous cell carcinoma tissues compared to normal, which is coincident with increased protein levels of CELF1. Surprisingly, loss of CELF1 expression in oral cancer cells dramatically increased IL-24 protein from undetectable levels to robust expression. We are currently exploring the mechanism of the CELF-1/IL-24 axis in mediating apoptosis in oral cancer cells and are expanding our studies to include other cancer types. These results suggest a novel mechanism by which the RNA binding protein CELF1 promotes oral cancer cell survival, through controlling the expression of a potent tumor suppressive protein and supports CELF1 as a viable target for the development of cancer therapeutic interventions. Citation Format: Reniqua House, Viswanathan Palanisamy. The RNA-binding protein CELF1 regulates the tumor suppressive protein IL-24/mda-7 expression in oral squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3508.

Mda-7/IL-24 Induces Cell Death in Neuroblastoma through a Novel Mechanism Involving AIF and ATM.

Advanced stages of neuroblastoma, the most common extracranial malignant solid tumor of the central nervous system in infants and children, are refractive to therapy. Ectopic expression of melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) promotes broad-spectrum antitumor activity in vitro, in vivo in preclinical animal models, and in a phase I clinical trial in patients with advanced cancers without harming normal cells. mda-7/IL-24 exerts cancer-specific toxicity (apoptosis or toxic autophagy) by promoting endoplasmic reticulum stress and modulating multiple signal transduction pathways regulating cancer cell growth, invasion, metastasis, survival, and angiogenesis. To enhance cancer-selective expression and targeted anticancer activity of mda-7/IL-24, we created a tropism-modified cancer terminator virus (Ad.5/3-CTV), which selectively replicates in cancer cells producing robust expression of mda-7/IL-24 We now show that Ad.5/3-CTV induces profound neuroblastoma antiproliferative activity and apoptosis in a caspase-3/9-independent manner, both in vitro and in vivo in a tumor xenograft model. Ad.5/3-CTV promotes these effects through a unique pathway involving apoptosis-inducing factor (AIF) translocation into the nucleus. Inhibiting AIF rescued neuroblastoma cells from Ad.5/3-CTV-induced cell death, whereas pan-caspase inhibition failed to promote survival. Ad.5/3-CTV infection of neuroblastoma cells increased ATM phosphorylation instigating nuclear translocation and increased γ-H2AX, triggering nuclear translocation and intensified expression of AIF. These results were validated further using two ATM small-molecule inhibitors that attenuated PARP cleavage by inhibiting γ-H2AX, which in turn inhibited AIF changes in Ad.5/3-CTV-infected neuroblastoma cells. Taken together, we elucidate a novel pathway for mda-7/IL-24-induced caspase-independent apoptosis in neuroblastoma cells mediated through modulation of AIF, ATM, and γ-H2AX. Cancer Res; 76(12); 3572-82. ©2016 AACR.

A combinatory use of adenoviruses expressing melanoma differentiation-associated gene-7 and replication-competent adenoviruses produces synergistic effects on pancreatic carcinoma cells.

Type 5 adenoviruses expressing mda-7 gene (Ad-mda-7) induced cell death in various kinds of human tumors, but pancreatic carcinoma cells were relatively resistant to Ad-mda-7-mediated cytotoxicity. We then examined whether infection of Ad-mda-7 together with replication-competent Ad produced combinatory cytotoxic effects. We prepared replication-competent Ad, defective of the E1B55kDa gene or activated by a transcriptional regulatory region of the midkine or the survivin gene of which the expression was up-regulated in human tumors. Type 5 Ad bearing the exogenous regulatory region were further modified by replacing the fiber-knob region with that of type 35 Ad. Pancreatic carcinoma cells were infected with replication-incompetent Ad-mda-7 and the replication-competent Ad. Combinatory effects were examined with the CalcuSyn software and cell cycle analyses. Ad-mda-7 and the replication-competent Ad achieved cytotoxicity to pancreatic carcinoma. A combinatory use of Ad-mda-7 and either Ad defective of the E1B55kDa gene or Ad activated by the regulatory region produced synergistic cytotoxic effects. Cell cycle analyses demonstrated that the combination increased sub-G1 populations. These data collectively suggest that expression of MDA-7 augments cytotoxicity of replication-competent Ad and achieves adjuvant effects on Ad-mediated cell death.

Melanoma differentiation-associated gene-7/interleukin-24 as a potential prognostic biomarker and second primary malignancy indicator in head and neck squamous cell carcinoma patients.

The significance of melanoma differentiation-associated gene-7/interleukin-24 (MDA-7/IL-24) expression in head and neck squamous cell carcinoma (HNSCC) remains unclear. This study was designed to investigate and evaluate the clinical significance of MDA-7/IL-24 expression in HNSCC by detecting expression by immunostaining in 131 HNSCC specimens. The function of MDA-7/IL-24 was investigated by real-time polymerase chain reaction (PCR) and Western blot in Ad5.mda-7-infected HNSCC cell lines. Our results showed that MDA-7/IL-24 was mainly expressed in the cytoplasm of HNSCC cells. MDA-7/IL-24 high patients presented with a favorable postoperative prognosis compared with MDA-7/IL-24 low patients, and high expression of MDA-7/IL-24 was significantly correlated with a lower incidence of second primary malignancies (SPMs) in the head and neck regions. In vitro assays showed that high expression of MDA-7/IL-24 could upregulate the expression of the epithelial terminal differentiation markers cytokeratin (KRT) 1, KRT4, KRT13, phosphorylated endoplasmic reticulum stress protein (p)-EIF2a, and the apoptosis-related protein cleaved caspase-3. It also downregulated the epithelial proliferative markers KRT5, KRT14, Integrin β4, and anti-apoptosis protein Bcl-2, which might be partially involved in the underlying mechanisms of Ad.mda-7-mediated HNSCC differentiation and apoptosis. Our results indicate that MDA-7/IL-24 can be a prognostic biomarker and an indicator of second primary malignancies (SPM) in HNSCC.

Characterization of the canine mda-7 gene, transcripts and expression patterns.

Human melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) displays potent growth suppressing and cell killing activity against a wide variety of human and rodent cancer cells. In this study, we identified a canine ortholog of the human mda-7/IL-24 gene located within a cluster of IL-10 family members on chromosome 7. The full-length mRNA sequence of canine mda-7 was determined, which encodes a 186-amino acid protein that has 66% similarity to human MDA-7/IL-24. Canine MDA-7 is constitutively expressed in cultured normal canine epidermal keratinocytes (NCEKs), and its expression levels are increased after lipopolysaccharide stimulation. In cultured NCEKs, the canine mda-7 pre-mRNA is differentially spliced, via exon skipping and alternate 5'-splice donor sites, to yield five splice variants (canine mda-7sv1, canine mda-7sv2, canine mda-7sv3, canine mda-7sv4 and canine mda-7sv5) that encode four protein isoforms of the canine MDA-7 protein. These protein isoforms have a conserved N-terminus (signal peptide sequence) and are dissimilar in amino acid sequences at their C-terminus. Canine MDA-7 is not expressed in primary canine tumor samples, and most tumor derived cancer cell lines tested, like its human counterpart. Unlike human MDA-7/IL-24, canine mda-7 mRNA is not expressed in unstimulated or lipopolysaccharide (LPS), concanavalin A (ConA) or phytohemagglutinin (PHA) stimulated canine peripheral blood mononuclear cells (PBMCs). Furthermore, in-silico analysis revealed that canonical canine MDA-7 has a potential 28 amino acid signal peptide sequence that can target it for active secretion. This data suggests that canine mda-7 is indeed an ortholog of human mda-7/IL-24, its protein product has high amino acid similarity to human MDA-7/IL-24 protein and it may possess similar biological properties to human MDA-7/IL-24, but its expression pattern is more restricted than its human ortholog.

Construction and identification of lentiviral vector containing human ILK-shRNA and mda7 gene

To construct and identify lentiviral vector containing human ILK-shRNA and mda7 gene. Based on the human ILK gene sequences, RNAi target sequences were designed and cloned into the lentiviral vector pSicoR-eGFP by restriction endonuclease HpaI and XhoI double digestion and T4 DNA ligase ligation. Based on the human mda7 gene sequences, PCR primers were designed to clone the full-length mda7, and were cloned into the lentiviral vector pLVX-Puro. After the candidate clones were identified by DNA sequencing, the recombinant plasmid and the three packaging plasmids were co-transfected into the human embryonic kidney 293T cells by lipofectamine 2000 to produce the lentiviral particles. Human prostate cancer PC-3 cells were infected with the constructed lentiviral vector. The ILK and mda7 expression levels in PC-3 cells were quantified by qPCR and Western blot, respectively. The effect of ILK and mda7 on proliferation and migration of PC-3 cells were assessed by MTT method and Transwell assay, respectively. ILK-pSicoR-eGFP and mda7-pLVX-Puro lentiviral vectors were successfully constructed. Strong green fluorescence was observed in the 293T cells under the fluorescent microscope after co-transfection of 293T cells with 4 plasmids of lentiviral vector. The transfection efficiency of the collected virus exceeded 90% in the 293T cells and the PC-3 cells were infected with the lentiviral particles with high efficiency. The A and B lentiviral vector inhibited the expression of ILK at both the mRNA and protein levels in PC-3 cells significantly. The mda7-pLVX-Puro lentiviral vector increased the expression of mda7 in PC-3 cells, and the ability was maintained for one month. Within 96 h, ILK and mad7 significantly inhibited the proliferation and migration of PC-3 cells (Ps<0.05). The lentiviral vectors of ILK knockdown and mda7 over-expression have been successfully constructed and identified. The recombinant lentivirus can efficiently infect human prostate cancer PC-3 cells, in which ILK expression is inhibited and mda7 is over-expressed.

Novel Mechanism of MDA-7/IL-24 Cancer-Specific Apoptosis through SARI Induction

Subtraction hybridization combined with induction of cancer cell terminal differentiation in human melanoma cells identified melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) and SARI (suppressor of AP-1, induced by IFN) that display potent antitumor activity. These genes are not constitutively expressed in cancer cells and forced expression of mda-7/IL-24 (Ad.mda-7) or SARI (Ad.SARI) promotes cancer-specific cell death. Ectopic expression of mda-7/IL-24 induces SARI mRNA and protein in a panel of different cancer cells, leading to cell death, without harming corresponding normal cells. Simultaneous inhibition of K-ras downstream extracellular signal-regulated kinase 1/2 signaling in pancreatic cancer cells reverses the translational block of MDA-7/IL-24 and induces SARI expression and cell death. Using SARI-antisense-based approaches, we demonstrate that SARI expression is necessary for mda-7/IL-24 antitumor effects. Secreted MDA-7/IL-24 protein induces antitumor "bystander" effects by promoting its own expression. Recombinant MDA-7/IL-24 (His-MDA-7) induces SARI expression, supporting the involvement of SARI in the MDA-7/IL-24-driven autocrine loop, culminating in antitumor effects. Moreover, His-MDA-7, after binding to its cognate receptors (IL-20R1/IL-20R2 or IL-22R/IL-20R2), induces intracellular signaling by phosphorylation of p38 MAPK, leading to transcription of a family of growth arrest and DNA damage inducible (GADD) genes, culminating in apoptosis. Inhibition of p38 MAPK fails to induce SARI following Ad.mda-7 infection. These findings reveal the significance of the mda-7/IL-24-SARI axis in cancer-specific killing and provide a potential strategy for treating both local and metastatic disease.

Stabilization of MDA-7/IL-24 for colon cancer therapy

Colon cancer is one of the most commonly diagnosed cancers in the United States. Recombinant MDA-7/IL-24 has showed its selective cytotoxicity against cancer cells, and Ad-mda7 (INGN-241) is currently under clinical investigation for solid tumors. Here, we investigated the expression of MDA-7/IL-24 in colorectal cancer (CRC) tissues from 202 patients. Compared with the adjacent mucosa, CRC tissues displayed significantly lower MDA-7/IL-24 levels. The MDA-7/IL-24 levels in CRC were significantly associated with patients’ survival rate in a 6-year period. These results indicate MDA-7/IL-24 level is both a diagnostic and prognostic biomarker for CRC, and support the role of MDA-7/IL-24 in the treatment of CRC. To elevate MDA-7/IL-24 level for colon cancer treatment, we successfully developed a small-molecule compound SC144 with the ability to up-regulate MDA-7/IL-24 expression via direct binding and stabilizing MDA-7/IL-24 in human colon cancer cells. Among the analogs tested, SC144 exhibited the highest cytotoxicity in a panel of colon cancer cell lines in a p53-independent manner, accompanied by cell cycle arrest in G0/G1 with downregulation of Cyclin D1 levels, and apoptosis induction with upregulation of cell surface-bound Fas/CD95. These results combined with our previous studies support the anticancer role of MDA-7/IL-24 as well as the clinical development of SC144 for colon cancer treatment.

Enhanced delivery of mda‐7/IL‐24 using a serotype chimeric adenovirus (Ad.5/3) in combination with the apogossypol derivative BI‐97C1 (Sabutoclax) improves therapeutic efficacy in low CAR colorectal cancer cells

Adenovirus (Ad)-based gene therapy represents a potentially viable strategy for treating colorectal cancer. The infectivity of serotype 5 adenovirus (Ad.5), routinely used as a transgene delivery vector, is dependent on Coxsackie-adenovirus receptors (CAR). CAR expression is downregulated in many cancers thus preventing optimum therapeutic efficiency of Ad.5-based therapies. To overcome the low CAR problem, a serotype chimerism approach was used to generate a recombinant Ad (Ad.5/3) that is capable of infecting cancer cells via Ad.3 receptors in a CAR-independent manner. We evaluated the improved transgene delivery and efficacy of Ad.5/3 recombinant virus expressing melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24), an effective wide-spectrum cancer-selective therapeutic. In low CAR human colorectal cancer cells RKO, wild-type Ad.5 virus expressing mda-7/IL-24 (Ad.5-mda-7) failed to infect efficiently resulting in lack of expression of MDA-7/IL-24 or induction of apoptosis. However, a recombinant Ad.5/3 virus expressing mda-7/IL-24 (Ad.5/3-mda-7) efficiently infected RKO cells resulting in higher MDA-7/IL-24 expression and inhibition of cell growth both in vitro and in nude mice xenograft models. Addition of the novel Bcl-2 family pharmacological inhibitor Apogossypol derivative BI-97C1 (Sabutoclax) significantly augmented the efficacy of Ad.5/3-mda-7. A combination regimen of suboptimal doses of Ad.5/3-mda-7 and BI-97C1 profoundly enhanced cytotoxicity in RKO cells both in vitro and in vivo. Considering the fact that Ad.5-mda-7 has demonstrated significant objective responses in a Phase I clinical trial for advanced solid tumors, Ad.5/3-mda-7 alone or in combination with BI-97C1 would be predicted to exert significantly improved therapeutic efficacy in colorectal cancer patients.

Novel Functions for mda-7/IL-24 and IL-24 delE5: Regulation of Differentiation of Acute Myeloid Leukemic Cells

Characterizing genes associated with leukemic cell differentiation may provide help for understanding mechanisms on the leukemia differentiation. The aim of this study is to investigate whether the expression of melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) could be induced during leukemia differentiation and whether mda-7/IL-24 plays a role in leukemia differentiation. We showed that the expression of mda-7/IL-24 and IL-24 delE5, an mda-7/IL-24 splice variant, was induced in U937 and HL60 cells during 12-O-tetradecanoylphorbol-13-acetate (TPA)-mediated monocytic differentiation. Activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway was required for their induction. Knockdown of mda-7/IL-24 and IL-24 delE5 resulted in significant inhibition of the monocytic differentiation induced by TPA. More importantly, ectopic overexpression of mda-7/IL-24 and IL-24 delE5 significantly induced U937 cells, HL60 cells, and blast cells from patients with acute myeloid leukemia-M5 to differentiate, whereas normal hematopoietic progenitors were not affected. Furthermore, the molecular effector associated with selective differentiation induction by mda-7/IL-24 and IL-24 delE5 may be reactive oxygen species (ROS), and the source of ROS generation was nicotinamide adenine dinucleotide phosphate oxidase. Taken together, our results reveal the mechanism by which TPA induces monocytic differentiation and show for the first time the specific differentiation-inducing effects of mda-7/IL-24 and IL-24 delE5 on human myeloid leukemic cells.

MDA-7/IL-24 as a cancer therapeutic: from bench to bedside.

The novel cytokine melanoma differentiation associated gene-7 (mda-7) was identified by subtractive hybridization in the mid-1990s as a protein whose expression increased during the induction of terminal differentiation, and that was either not expressed or was present at low levels in tumor cells compared with non-transformed cells. On the basis of conserved structure, chromosomal location and cytokine-like properties, MDA-7, has now been classified as a member of the expanding interleukin (IL)-10 gene family and designated as MDA-7/IL-24. Multiple studies have shown that the expression of MDA-7/IL-24 in a wide variety of tumor cell types, but not in the corresponding equivalent non-transformed cells, causes their growth arrest and ultimately cell death. In addition, MDA-7/IL-24 has been noted to be a radiosensitizing cytokine, which is partly because of the generation of reactive oxygen species and ceramide that cause endoplasmic reticulum stress. Phase I clinical trial data has shown that a recombinant adenovirus expressing MDA-7/IL-24 [Ad.mda-7 (INGN-241)] was safe and had measurable tumoricidal effects in over 40% of patients, which strongly argues that MDA-7/IL-24 may have significant therapeutic value. This review describes what is known about the impact of MDA-7/IL-24 on tumor cell biology and its potential therapeutic applications.

Tumour suppressor function of MDA-7/IL-24 in human breast cancer

IntroductionMelanoma differentiation associated gene-7 (MDA-7), also known as interleukin (IL)-24, is a tumour suppressor gene associated with differentiation, growth and apoptosis. However, the mechanisms underlying its anti-neoplastic activity, tumour-specificity and efficacy across a spectrum of human cancers have yet to be fully elucidated. In this study, the biological impact of MDA-7 on the behavior of breast cancer (BC) cells is evaluated. Furthermore, mRNA expression of MDA-7 is assessed in a cohort of women with BC and correlated with established pathological parameters and clinical outcome.MethodsThe human BC cell line MDA MB-231 was used to evaluate the in-vitro impact of recombinant human (rh)-MDA-7 on cell growth and motility, using a growth assay, wounding assay and electric cell impedance sensing (ECIS). Localisation of MDA-7 in mammary tissues was assessed with standard immuno-histochemical methodology. BC tissues (n = 127) and normal tissues (n = 33) underwent RNA extraction and reverse transcription, MDA-7 transcript levels were determined using real-time quantitative PCR. Transcript levels were analyzed against tumour size, grade, oestrogen receptor (ER) status, nodal involvement, TNM stage, Nottingham Prognostic Index (NPI) and clinical outcome over a 10 year follow-up period.ResultsExposure to rh-MDA-7 significantly reduced wound closure rates for human BC cells in-vitro. The ECIS model demonstrated a significantly reduced motility and migration following rh-MDA-7 treatment (p = 0.024). Exposure to rh-MDA-7 was only found to exert a marginal effect on growth. Immuno-histochemical staining of human breast tissues revealed substantially greater MDA-7 positivity in normal compared to cancer cells. Significantly lower MDA-7 transcript levels were identified in those predicted to have a poorer prognosis by the NPI (p = 0.049) and those with node positive tumours. Significantly lower expression was also noted in tumours from patients who died of BC compared to those who remained disease free (p = 0.035). Low levels of MDA-7 were significantly correlated with a shorter disease free survival (mean = 121.7 vs. 140.4 months, p = 0.0287) on Kaplan-Meier survival analysis.ConclusionMDA-7 significantly inhibits the motility and migration of human BC cells in-vitro. MDA-7 expression is substantially reduced in malignant breast tissue and low transcript levels are significantly associated with unfavourable pathological parameters, including nodal positivity; and adverse clinical outcomes including poor prognosis and shorter disease free survival. MDA-7 offers utility as a prognostic marker and potential for future therapeutic strategies.

HDAC4 inhibits the transcriptional activation of mda-7/IL-24 induced by Sp1

Melanoma differentiation-associated gene/interleukin-24 (mda-7/IL-24) is a cytokine that can activate monocytes and T helper 2 cells. The expression of mda-7/IL-24 gradually fades with the progression of melanoma, and it is undetectable at the metastatic stage. Ectopic expression of mda-7/IL-24 selectively suppresses growth and induces apoptosis in cancer cells with little harm to normal cells. However, the transcriptional regulation of the mda-7/IL-24 gene has not been extensively studied. In this study, we show that the expression of mda-7/IL-24 was upregulated by the histone deacetylase (HDAC) inhibitors trichostatin A (TSA) and sodium butyrate (NaBu), whereas it was downregulated by HDAC4. We also found that the histone acetylation level and the binding of the transcriptional factor Sp1 to the mad-7 promoter were reduced upon HDAC4 treatment. Moreover, the HDAC inhibitor TSA induced histone hyperacetylation and stimulated Sp1 binding to the mda-7/IL-24 promoter, which in turn enhanced the expression of mda-7/IL-24. Therefore, we conclude that histone acetylation modification plays an important role in the regulation of mda-7/IL-24 and that the transcription factor Sp1 participates in this process.

OSU-03012 enhances Ad.7-induced GBM cell killing via ER stress and autophagy and by decreasing expression of mitochondrial protective proteins

The present studies focused on determining whether the autophagy-inducing drug OSU-03012 (AR-12) could enhance the toxicity of recombinant adenoviral delivery of melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) in glioblastoma multiforme (GBM) cells. The toxicity of a recombinant adenovirus to express MDA-7/IL-24 (Ad.mda-7) was enhanced by OSU-03012 in a diverse panel of primary human GBM cells. The enhanced toxicity correlated with reduced ERK1/2 phosphorylation and expression of MCL-1 and BCL-XL, and was blocked by molecular activation of ERK1/2 and by inhibition of the intrinsic, but not the extrinsic, apoptosis pathway. Both OSU-03012 and expression of MDA-7/IL-24 increased phosphorylation of PKR-like endoplasmic reticulum kinase (PERK) that correlated with increased levels of autophagy and expression of dominant negative PERK blocked autophagy induction and tumor cell death. Knockdown of ATG5 or Beclin1 suppressed OSU-03012 enhanced MDA-7/IL-24-induced autophagy and blocked the lethal interaction between the two agents. Ad.mda-7-infected GBM cells secreted MDA-7/IL-24 into the growth media and this conditioned media induced expression of MDA-7/IL-24 in uninfected GBM cells. OSU-03012 interacted with conditioned media to kill GBM cells and knockdown of MDA-7/IL-24 in these cells suppressed tumor cell killing. Collectively, our data demonstrate that the induction of autophagy and mitochondrial dysfunction by a combinatorial treatment approach represents a potentially viable strategy to kill primary human GBM cells.