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Biomedical subjects

Elizabeth A Grimm

Publications and source records attributed to Elizabeth A Grimm.

At least 19 recordsLinked to original sources
PubMed2006

WP760, a melanoma selective drug.

PURPOSE: Our goal was to perform studies on the specificity and antimelanoma mechanism of a novel bis-anthracycline, WP760. WP760 initially identified in the NCI 160 screen as anti-melanoma. METHODS: The methyl thiazolyl tetrazolium reduction (MTT) assay was used to test tumor cell growth inhibition; confocal microscopy to view WP760 intracellular distribution; flow cytometry for cell-cycle arrest and apoptosis; and Western blotting was employed to identify and compare quantities and kinetics of cell growth related molecule levels. RESULTS: WP760 induced G(2)/M-phase cell-cycle arrest and apoptosis in melanoma cell lines and short-term melanoma explants established from clinical specimens in a time and concentration dependent manner at nM concentrations. In contrast, effects on fibroblasts and A549 lung cancer cells required higher concentrations, suggesting that WP760 possesses selectivity for melanoma. Molecular studies indicated that WP760 induced p53 stabilization, checkpoint kinase 2 and p27(Kip1) protein upregulation, and activation of caspase-3. Endogenous nitric oxide (NO) production has been implicated in the chemoresistance of melanoma; WP760 caused inhibition of the inducible nitric oxide synthase (iNOS) protein as well as inhibition of phosphorylation of ERK, known to drive the iNOS pathway. Based on WP760 localization into mitochondria, and caspase-3 inhibitor block the killing of WP760, the intrinsic pathway of apoptosis appears to have been activated. CONCLUSIONS: Our results indicate that WP760 affects a critical and unique set of growth regulatory effects in melanoma, and is a promising candidate for further preclinical studies.

Anthracyclines↗
PubMed2006

Genetic variants of the vitamin D receptor gene alter risk of cutaneous melanoma.

Sunlight causes DNA damage but also induces production of vitamin D whose metabolite 1,25-(OH)2D3 has antiproliferative and pro-differentiative effects in both melanocytes and cutaneous melanoma (CM) cells mediated through the vitamin D receptor (VDR). We hypothesized that genetic polymorphisms of VDR are associated with risk of CM. In a hospital-based case-control study of 602 non-Hispanic white CM patients and 603 cancer-free control subjects frequency matched by age and sex, we genotyped two VDR polymorphisms (TaqI and FokI) and assessed their association with CM risk. We found that a significantly decreased risk was associated with VDR-TaqI Tt (adjusted odds ratio (OR), 0.70; 95% confidence interval (CI), 0.54-0.90) and Tt+tt (OR=0.70; 95% CI, 0.55-0.89) genotypes, compared with the VDR-TaqI TT genotype, whereas an increased risk was associated with VDR-FokI Ff genotype (OR=1.32; 95% CI, 1.03-1.68), and a borderline significantly increased risk was associated with Ff+ff (OR=1.26; 95% CI, 1.00-1.59) genotypes, compared with the VDR-FokI FF genotype. In conclusion, genetic variants (i.e., TaqI t protective allele and FokI f risk allele) in VDR may alter risk of CM.

Alleles↗
PubMed2006

Tumor iNOS predicts poor survival for stage III melanoma patients.

Inducible nitric oxide synthase (iNOS) produces nitric oxide, which has growth promoting activity in melanoma. A preliminary study of tumors from patients with Stage III melanoma who had received neo-adjuvant therapy revealed an association of tumor iNOS expression with shortened survival. The objective of the present study was to determine whether iNOS expression in tumors of newly diagnosed, untreated Stage III patients is predictive of survival. iNOS expression was examined by immunohistochemistry in tumors from 132 patients. The staining was evaluated for percentage of positive cells (Number score) and the intensity of staining (Intensity score). The association of iNOS expression with overall and disease-specific survival was tested in univariate and multivariate Cox proportional hazards regression models that included other known prognostic factors. Results of the univariate analysis demonstrated that the presence of iNOS in a patient's tumor, whether graded on the basis of Number or Intensity score, was associated with a significant increase in the hazard ratio of death from melanoma. These findings were corroborated by median survival data estimated from Kaplan Meier analysis. In the multivariate model including iNOS number or intensity, gender, age, number of lymph nodes, macroscopic disease and in-transit disease, only iNOS expression predicted survival. We conclude that a significant association exists between tumor iNOS expression and shortened survival in untreated Stage III melanoma patients. The ability of iNOS to predict outcomes for these patients may be independent of other known prognostic factors, providing a new molecular marker with significant potential for clinical utility.

Adolescent↗
PubMed2006

Human interleukin 24 (MDA-7/IL-24) protein kills breast cancer cells via the IL-20 receptor and is antagonized by IL-10.

The melanoma differentiation-associated gene-7 (mda-7/IL-24) is a unique member of the interleukin 10 (IL-10) family of cytokines, with ubiquitous tumor cell pro-apoptotic activity. Recent data have shown that IL-24 is secreted as a glycosylated protein and functions as a pro-Th1 cytokine and as a potent anti-angiogenic molecule. In this study, we analyzed the activity of Ad-mda7 and its protein product, secreted IL-24, against human breast cancer cells. We show that Ad-mda7 transduction of human breast cancer cells results in G(2)/M phase cell cycle arrest and apoptotic cell death, which correlates with secretion of IL-24 protein. Neutralizing antibody against IL-24 significantly inhibited Ad-mda7 cytotoxicity. IL-24 and IL-10 both engage their cognate receptors on breast cancer cells resulting in phosphorylation and activation of STAT3, however, IL-10 receptor binding failed to induce cell killing, indicating that tumor cell killing by IL-24 is independent of STAT3 phosphorylation. Treatment with exogenous IL-24 induced apoptosis in breast cancer cells and this effect was abolished by addition of anti-IL-24 antibody or anti-IL-20R1, indicating that bystander cell killing is mediated via IL-24 binding to the IL-20R1/IL-20R2 heterodimeric receptor complex. Co-administration of the related cytokine IL-10 inhibited killing mediated by IL-24 and concomitantly inhibited IL-24 mediated up-regulation of the tumor suppressor proteins, p53 and p27(Kip1). In summary, we have defined a tumor-selective cytotoxic bystander role for secreted IL-24 protein and identified a novel receptor-mediated death pathway in breast cancer cells, wherein the related cytokines IL-24 and IL-10 exhibit antagonistic activity.

Apoptosis↗
PubMed2006

Genetic variants of the ADPRT, XRCC1 and APE1 genes and risk of cutaneous melanoma.

Sunlight causes various kinds of DNA damage, including oxidative lesions that are removed effectively by the base excision repair (BER) pathway, in which ADPRT, XRCC1 and APE1 play a key role. However, genetic variation in these genes may alter their functions. We hypothesized that ADPRT, XRCC1 and APE1 polymorphisms are associated with risk of cutaneous melanoma (CM). In a hospital-based case-control study of 602 CM patients and 603 cancer-free control subjects frequency matched on age, sex and ethnicity, we genotyped for three non-synonymous single nucleotide polymorphisms (SNPs) (i.e. the ADPRT Val762Ala, XRCC1 Arg399Gln and APE1Asp148Glu) and assessed their associations with risk of CM. We found no significant difference in the allele frequencies between cases and controls for any of these three SNPs. However, we found that, compared with the APE1 Asp/Asp genotype, a significantly decreased risk of CM was associated with the APE1 Asp/Glu [adjusted odds ratio (OR), 0.60; 95% confidence interval (CI), 0.41-0.86], Glu/Glu (OR, 0.58; 95% CI, 0.38-0.88) and combined APE1 Asp/Glu+Glu/Glu (OR, 0.59; 95% CI, 0.42-0.83) genotypes, but not for other XRCC1 variant genotypes. Moreover, there was evidence for a possible gene-gene interaction between XRCC1 and APE1 variants in the association with risk of CM (P=0.030). We conclude that the APE1 Glu variant may have an effect or interact with XRCC1 in the etiology of CM or in linkage disequilibrium with other untyped protective alleles. Larger studies with more SNPs in the BER genes are needed to verify these findings.

Adult↗
PubMed2006

Polymorphisms of the FAS and FAS ligand genes associated with risk of cutaneous malignant melanoma.

The FAS/FAS ligand (FASLG) system has a key role in regulating cell growth and thus tumorigenesis. Functional promoter polymorphisms of the FAS and FASLG genes alter the transcriptional activities, but no published study has investigated the role of these polymorphisms in the etiology of cutaneous malignant melanoma (CMM). In a hospital-based, case-control study of 602 non-Hispanic white CMM patients and 603 cancer-free age- and sex-matched control subjects, we genotyped FAS-1377G>A, FAS-670A>G, FASLG-844T>C and FASLG-IVS2nt-124G>A polymorphisms and assessed their respective associations with CMM risk. We found that an increased risk of CMM was associated with the FAS-1377GG [adjusted odds ratio (OR)=1.32; 95% confidence interval (CI)=1.00-1.75 for -1377GG] and -670AA (adjusted OR=1.28; 95% CI=1.00-1.65 for -670AA) genotypes compared to the -1377AA/AG and -670AG/GG genotypes, respectively; an increased risk of CMM was associated with the FASLG-IVS2nt-124AG+GG (OR=1.54; 95% CI=1.18-2.01) genotype compared to the AA genotype, but no evident risk was associated with any of the FAS-844T>C genotypes. In the combined analysis of these four variant alleles, we found that, compared to those having 0-3 variants, those having 4-8 variant alleles had a significantly increased risk for CMM (OR=1.38; 95% CI=1.10-1.73), and this risk was more pronounced in subgroups of old (>50 years) males, and those who were at low risk of sunlight-induced CMM, except for having fair skin colour, moles, dysplastic nevi and a family history of cancer. In conclusion, genetic variants in the FAS and FASLG genes may contribute to the etiology of CMM in the general population, particularly in those with a low risk of sunlight-induced CMM.

Alleles↗
PubMed2006

Polymorphisms in the DNA repair genes XPC, XPD, and XPG and risk of cutaneous melanoma: a case-control analysis.

Sunlight causes DNA damage, including bulky lesions that are removed effectively by the nucleotide-excision repair (NER) pathway. There are at least eight core NER proteins participating in the pathway, and genetic variations in their genes may alter NER functions. We hypothesized that some NER variants are associated with risk of cutaneous melanoma. In a hospital-based case-control study of 602 non-Hispanic White patients with cutaneous melanoma and 603 age- and sex-matched cancer-free controls, we genotyped five common non-synonymous single-nucleotide polymorphisms identified to date and assessed their associations with risk of cutaneous melanoma. We found that a significantly increased risk of cutaneous melanoma was associated with XPD 751Lys/Gln [adjusted odds ratio (OR), 1.55 and 95% confidence interval (95% CI), 1.12-2.16] and XPD 751Gln/Gln (OR, 1.66; 95% CI, 1.03-2.68) genotypes compared with the XPD 751Lys/Lys genotype as well as XPD312Asp/Asn (OR, 1.54; 95% CI, 1.11-2.12) and XPD312Asn/Asn (OR, 1.75; 95% CI, 1.05-2.90) genotypes compared with the XPD 312Asp/Asp genotype. This increased risk was not observed in the other three XPC and XPG single-nucleotide polymorphisms. Moreover, the number of the observed XPD at-risk genotypes (i.e., 312Asn/Asn+Asn/Asp and 751Gln/Gln+Lys/Gln) was associated with cutaneous melanoma risk in a dose-response manner (OR, 1.47; 95% CI, 0.97-2.23 for one at-risk genotype; OR, 1.83; 95% CI, 1.29-2.61 for two at-risk genotypes; P(trend) < 0.001). However, we found no evidence of any interaction between XPD genotypes with XPC and XPG genotypes or the known risk factors. We concluded that genetic variants of the XPD gene might serve as biomarkers for susceptibility to cutaneous melanoma.

Case-Control Studies↗
PubMed2005

Cytokine induction of interleukin-24 in human peripheral blood mononuclear cells.

Interleukin-24 (IL-24) is a recently identified member of the IL-10 family of cytokines. It was originally identified as a tumor suppressor molecule, melanoma differentiation-associated gene 7, and then renamed IL-24 and classified as a cytokine, based on its chromosomal location in the IL-10 locus, its mRNA expression in leukocytes, and its secretory sequence elements. Here, we correlate the kinetics of IL-24 mRNA and protein expression in human peripheral blood mononuclear cells (PBMC) stimulated by polyclonal activators phytohemagglutinin (PHA) and lipopolysaccharide (LPS) or by allogeneic major histocompatibility complex. PHA-stimulated PBMC express IL-24 mRNA, reaching peak levels at 8-12 h after stimulation. Protein expression, as measured by intracellular flow cytometry, followed the message, reaching maximum expression at 24 h. Subset analysis of mitogen-stimulated PBMC showed that IL-24 was expressed primarily in T cells and macrophages. Expression of IL-24 in mitogen-stimulated PBMC is the result of cytokine stimulation. Individual cytokines including IL-2, IL-7, IL-15, tumor necrosis factor alpha, granulocyte macrophage-colony stimulating factor, and IL-1beta stimulate the expression of IL-24 mRNA and protein, whereas interferons and T helper cell type 2 cytokines fail to induce substantial IL-24. When LPS- or PHA-stimulated cells were treated with Actinomycin D, IL-24 mRNA persisted at high levels over the 4-h course of treatment. These data strongly suggest that the expression of IL-24 in human PBMC results from cytokine stimulation and is regulated at the post-transcriptional level through stabilization of IL-24 mRNA.

Antibodies↗
PubMed2005

Intratumoral injection of INGN 241, a nonreplicating adenovector expressing the melanoma-differentiation associated gene-7 (mda-7/IL24): biologic outcome in advanced cancer patients.

The mda-7 gene (approved gene symbol IL24) is a novel tumor suppressor gene with tumor-apoptotic and immune-activating properties. We completed a Phase I dose-escalation clinical trial, in which a nonreplicating adenoviral construct expressing the mda-7 transgene (INGN 241; Ad-mda7) was administered intratumorally to 22 patients with advanced cancer. Excised tumors were evaluated for vector-specific DNA and RNA, transgenic MDA-7 expression, and biological effects. Successful gene transfer as assessed by DNA- and RT-PCR was demonstrated in 100% of patients evaluated. DNA analyses demonstrated a dose-dependent penetration of INGN 241 (up to 4 x 10(8) copies/mug DNA at the 2 x 10(12) vp dose). A parallel distribution of vector DNA, vector RNA, MDA-7 protein expression, and apoptosis induction was observed in all tumors, with signals decreasing with distance away from the injection site. Additional evidence for bioactivity of INGN 241 was illustrated via regulation of the MDA-7 target genes beta-catenin, iNOS, and CD31. Transient increases (up to 20-fold) of serum IL-6, IL-10, and TNF-alpha were observed. Significantly higher elevations of IL-6 and TNF-alpha were observed in patients who responded clinically to INGN 241. Patients also showed marked increases of CD3+CD8+ T cells posttreatment, suggesting that INGN 241 increased systemic TH1 cytokine production and mobilized CD8+ T cells. Intratumoral delivery of INGN 241 induced apoptosis in a large volume of tumor and elicited tumor-regulatory and immune-activating events that are consistent with the preclinical features of MDA-7/IL-24.

Adenoviridae↗
PubMed2005

mda-7/IL24 kills pancreatic cancer cells by inhibition of the Wnt/PI3K signaling pathways: identification of IL-20 receptor-mediated bystander activity against pancreatic cancer.

The melanoma differentiation-associated gene (mda-7; approved gene symbol IL24) is a tumor suppressor gene whose protein expression in normal cells is restricted to the immune system and to melanocytes. Recent studies have shown that mda-7 gene transfer inhibits cell growth and induces apoptosis in melanoma, lung cancer, breast cancer, and other tumor types through activation of various intracellular signaling pathways. In the current study, we demonstrate that Ad-mda7 transduction of human pancreatic cancer cells results in G2/M cell cycle arrest and cell killing. Cytotoxicity is mediated via apoptosis in a time- and dose-dependent manner. Tumor cell killing correlates with regulation of proteins involved in the Wnt and PI3K pathways: beta-catenin, APC, GSK-3, JNK, and PTEN. Additionally, we identify bystander cell killing activated by exposure of pancreatic tumor cells to secreted human MDA-7 protein. In pancreatic tumor cells, exogenous MDA-7 protein activates STAT3 and kills cells via engagement of IL-20 receptors. The specificity of bystander killing is demonstrated using neutralizing anti-MDA-7 antibodies and anti-receptor antibodies, which inhibit the apoptotic effects. In sum, we show that Ad-mda7 is able to induce growth inhibition and apoptosis in pancreatic cancer cells via inhibition of the Wnt/PI3K pathways and identify a novel bystander mechanism of MDA-7 killing in pancreatic cancer that functions via IL-20 receptors.

Apoptosis↗
PubMed2005

NO news is not necessarily good news in cancer.

The diatomic radical nitric oxide has been the focus of numerous studies involved with every facet of cancer. It has been implicated in carcinogenesis, progression, invasion, metastasis, angiogenesis, escape from immune surveillance, and modulation of therapeutic response. In recent years, an increasing number of studies have suggested the possible involvement of nitric oxide in multiple cancer types, including melanoma. It is perhaps not surprising that conflicting viewpoints have arisen as to whether nitric oxide is beneficial or deleterious in cancer. However, it has become clear that nitric oxide possesses modulatory properties in a number of signal transduction pathways that depend on concentration and context. Our laboratory has shown that tumor expression of inducible nitric oxide synthase in melanoma patients results in poor survival. Furthermore, we demonstrated that the removal of endogenous nitric oxide in melanoma cell lines led to increased sensitivity to cisplatin-induced apoptosis in a p53-dependent manner. Others have shown anti-apoptotic properties of NO in melanoma cells. However, several studies also suggest that NO can inhibit metastasis and diminish resistance. Despite the apparently conflicting observations, it is evident that NO is involved in melanoma pathology. The purpose of this review is to summarize the current literature relating to the role of NO in cancer with particular emphasis on its relevance to therapeutic resistance in melanoma. Recent evidence suggests the involvement of an intricate and complex interplay between reactive nitrogen species and reactive oxygen species. The importance of nitric oxide and its balance with other oxidative agents in the regulation of cancer cell response to therapies will be discussed. This balance may serve as an important focal point in determining patient response to therapy. The ability to control this balance could significantly influence outcome.

Animals↗
PubMed2004

Expression of thyrotropin-releasing hormone by human melanoma and nevi.

PURPOSE: Thyrotropin-releasing hormone (TRH) is a tripeptide hormone produced by the hypothalamus in response to hypothyroidism. RNA transcripts for the TRH prohormone have recently been described in melanoma cell lines. To expand these findings, we have examined cultured melanoma cells and melanocytes, human melanoma tumors, and nevi for the expression of TRH. EXPERIMENTAL DESIGN: Five melanoma cell lines were analyzed by reverse transcription-PCR/Southern blotting for preproTRH message. The same melanoma lines and two melanocyte lines were examined by immunocytochemistry for TRH protein expression and for growth response to exogenous TRH. Immunohistochemistry was used to test for TRH protein in sections of 19 melanomas, 33 dysplastic nevi, and 27 benign nevi. RESULTS: TRH message and protein were detected in all melanoma cell lines examined. Melanocytes were also found to express TRH protein. Four of the five melanoma cell lines but neither melanocyte line responded with a increase in proliferation to low concentrations of exogenous TRH. TRH immunoreactivity was observed in 12 of 19 melanomas (63%), 23 of 33 (69.7%) dysplastic nevi, and 14 of 27 (51.9%) benign nevi. Expression in dysplastic nevi was significantly greater than in benign nevi. Upon separate analysis of nevi from melanoma patients, the difference between dysplastic and benign nevi was even more significant. However, in healthy individuals, no difference between dysplastic and benign nevi was observed. Furthermore, dysplastic nevi from melanoma patients had a significantly higher percentage of TRH-positive cells when compared with healthy individuals. CONCLUSIONS: TRH is commonly expressed by melanomas and dysplastic nevi and may function as a melanoma autocrine growth factor. The presence of TRH in dysplastic nevi may be predictive for the development of melanoma. Our findings have significant clinical and biological implications for future research into the early stages of melanoma initiation and progression.

Cell Line, Tumor↗
PubMed2004

Pilot study of high-dose, concurrent biochemotherapy for advanced melanoma.

BACKGROUND: Durable complete response rates ranging from 5% to 20% have been reported in association with biochemotherapy for patients with metastatic melanoma, with response rates on the low end of this range being observed in trials that used lower doses and less intense treatment schedules. In the current study, the authors addressed the feasibility of increasing the doses of agents used in concurrent biochemotherapy. METHODS: Three patients with metastatic melanoma were enrolled at each of six concurrent biochemotherapy dose levels. The doses were as follows: dacarbazine 800 mg/m(2) or 1000 mg/m(2) (Day 1); cisplatin 25 mg/m(2) or 30 mg/m(2) (Days 1-4); vinblastine 1.6 mg/m(2) or 1.8 mg/m(2) (Days 1-5); interleukin-2 9 million units (MU) per m(2) or 12 MU/m(2) as a 24-hour continuous infusion (Days 1-4); and interferon-alpha-2b 5 MU/m(2), 10 MU/m(2), or 15 MU/m(2) (Days 1-5) and 5 MU/m(2) (Days 7, 9, and 11) administered subcutaneously. RESULTS: Of the 19 patients who were enrolled, 18 were evaluable for toxicity and response. Sixty-nine treatment courses were administered in total (median, 4 courses per patient; range, 1-6 courses per patient), with reduction of the dose of at least 1 agent being required in 7 courses (10%). Twenty-six courses were delayed by a median of 7 days (range, 3-29 days), with interferon-alpha-2b administration frequently omitted because of thrombocytopenia, most often after Day 5. Blood product support was required in 40 courses. Dose-limiting toxic effects included global encephalopathy, renal and hepatic dysfunction, pancreatitis, and ileus. There was 1 complete response, and there were 10 partial responses. The median time to disease progression was 6.9 months, and the median survival duration was 12.2 months. CONCLUSIONS: Although dose intensification can be achieved safely in patients with advanced melanoma, other strategies should be pursued to enhance the clinical activity of biochemotherapy as a response induction regimen.

Adult↗
PubMed2004

Analysis of dendritic cells in tumor-free and tumor-containing sentinel lymph nodes from patients with breast cancer.

INTRODUCTION: Sentinel lymph node (SLN) biopsy allows identification of the first lymph node into which a primary tumor drains. In breast cancer, identification of tumor cells in the SLNs is a predictor of the tumor's metastatic potential. In the present article, we tested the hypotheses that a positive immune response can occur in tumor-free SLNs and that the activation state of dendritic cells (DCs), the major antigen presenting cells within SLNs, predicts the immune status and metastatic potential of the tumor. METHODS: Fifty paraffin-embedded SLN sections, 25 tumor-free and 25 tumor-containing, from patients with breast cancer were analyzed by immunohistochemistry to determine the immune maturation state of their DCs. In addition, 12 lymph nodes from noncancer-containing breasts were analyzed. Tissues were stained with antibodies against CD3, MHC class II, CD1a, CD83, IL-10, and IL-12. Mature DCs were defined by CD83 expression and immature DCs by CD1a expression. RESULTS: We found a trend toward higher numbers of mature CD83-positive DCs in tumor-free SLNs than in tumor-containing SLNs (P = 0.07). In addition, tumor-free SLNs were more likely to contain cells expressing IL-10 (P = 0.02) and, to a lesser extent, IL-12 (P = 0.12). In contrast, when all SLNs, both tumor-free and tumor-containing, were compared with uninvolved lymph nodes, the numbers of mature and immature DCs were similar. CONCLUSIONS: Our results suggest tumor-free SLNs are immunologically competent and potentially a site of tumor-specific T-cell activation, as evidenced by the presence of greater numbers of mature DCs and cytokine-producing cells in tumor-free SLNs.

Adult↗
PubMed2004

MDA-7/IL-24 is a unique cytokine--tumor suppressor in the IL-10 family.

The melanoma differentiation associated gene-7 (mda-7) cDNA was isolated by virtue of being induced during melanoma differentiation. Initial gene transfer studies convincingly demonstrated potent antitumor effects of mda-7. Further studies showed that the mechanism of antitumor activity was due to induction of apoptosis. Most striking was the tumor-selective killing by mda-7 gene transfer--normal cells were unaffected by Adenoviral delivery of mda-7 (Ad-mda7). A variety of molecules implicated in apoptosis and intracellular signaling are regulated by Ad-mda7 transduction. Different apoptosis effector proteins are regulated in different tumor types, suggesting that Ad-mda7 may regulate various signaling pathways. mda-7 encodes a secreted protein, MDA-7, which has now been designated as IL-24, and is a novel member of the IL-10 cytokine family. MDA-7/IL-24 protein is actively secreted from cells after mda-7 gene transfer. In human peripheral blood mononuclear cells (PBMC), STAT3 activation by MDA-7/IL-24 is followed by elaboration of secondary Th1 cytokines, demonstrating that MDA-7/IL-24 is a pro-Th1 cytokine. Furthermore, MDA-7/IL-24 is antagonized by the prototypic Th2 cytokine IL-10. MDA-7/IL-24 protein is endogenously expressed in cultured NK and B-cells and is also expressed in dendritic cells in tissues. MDA-7/IL-24 protein is expressed in nevi and melanoma primary tumors, to varying degrees, but is rarely expressed in malignant melanoma or other human tumors evaluated. Indeed, loss of MDA-7/IL-24 protein expression correlates strongly with melanoma tumor invasion and disease progression. The "bystander" effects proposed for MDA-7/IL-24 protein include immune stimulation, antiangiogenesis and receptor-mediated cytotoxicity. Thus, mda-7 is a unique multifunctional cytokine in the IL-10 family and may have potent antitumor utility in a clinical setting.

Cytokines↗
PubMed2004

The tumor suppressor activity of MDA-7/IL-24 is mediated by intracellular protein expression in NSCLC cells.

mda-7/IL-24 (HGMW-approved symbol IL24) is a tumor suppressor gene whose expression is lost during tumor progression. Gene transfer using adenoviral mda-7/IL-24 (Ad-mda7) exhibits minimal toxicity on normal cells while inducing potent apoptosis in a variety of cancer cell lines. Ad-mda7-transduced cells express high levels of MDA-7 protein intracellularly and also secrete a soluble form of MDA-7 protein. In this study, we sought to determine whether the intracellular or secreted MDA-7 protein was responsible for anti-tumor activity in H1299 lung tumor cells. Ad-mda7 transduction of lung tumor cells increased expression of stress-related proteins, including BiP, GADD34, PP2A, caspases 7 and 12, and XBP-1, consistent with activation of the UPR pathway, a key sensor of endoplasmic reticulum (ER)-mediated stress. Blocking secretion of MDA-7 did not inhibit apoptosis, demonstrating that intracellular MDA-7 was responsible for cytotoxicity. Consistent with this result, when applied directly to lung cancer cells, soluble MDA-7 protein exhibited minimal cytotoxic effect. We then generated mda-7 expression constructs using vectors that target the expressed protein to various subcellular compartments, including cytoplasm, nucleus, and ER. Only full-length and ER-targeted MDA-7 elicited cell death in tumor cells. Thus in lung cancer cells, Ad-mda7 activates the UPR stress pathway and induces apoptosis via intracellular MDA-7 expression in the secretory pathway.

Adenoviridae↗
PubMed2004

Bystander activity of Ad-mda7: human MDA-7 protein kills melanoma cells via an IL-20 receptor-dependent but STAT3-independent mechanism.

The melanoma differentiation-associated gene-7 (mda-7/IL24) is a unique member of the IL-10 family of cytokines, with ubiquitous tumor cell proapoptotic activity. Transduction of tumor or normal cells with the mda-7 gene results in secretion of glycosylated MDA-7 protein. Recent data indicate that secreted MDA-7 protein functions as a pro-Th1 cytokine and as a potent antiangiogenic molecule. MDA-7 protein binds two distinct type II cytokine heterodimeric receptor complexes, IL-20R1/IL-20R2 (type 1 IL-20R) and IL-22R1/IL-20R2 (type 2 IL-20R). In this study we analyzed the activity of glycosylated secreted MDA-7 against human melanoma cells. MDA-7 protein induces phosphorylation and nuclear translocation of STAT3 in melanoma cells via both type 1 and type 2 IL-20R. MDA-7 induces dose-dependent cell death in melanoma tumor cells. MDA-7 receptor engagement results in up-regulation of BAX and subsequent apoptosis induction; this effect is mediated by STAT3-independent signaling. Additional IL-10 family members (IL-10, -19, -20, and -22) also activate STAT3; however, these ligands do not activate death pathways in melanoma. In normal cells, MDA-7 can bind to its cognate receptors and induce phosphorylation of STAT3, without cytotoxic sequelae. This study defines a tumor-selective cytotoxic bystander role for secreted MDA-7 protein and identifies a novel receptor-mediated, STAT3-independent, and PKR-independent death pathway.

Active Transport, Cell Nucleus↗