Defining the mechanism by which IFN-β dowregulates c-myc expression in human melanoma cells: pivotal role for human polynucleotide phosphorylase (hPNPaseold-35)

Sarkar, Devanand; Park, E S; Fisher, Paul B.

doi:10.1038/sj.cdd.4401829

Cited by 46 publications

(47 citation statements)

References 36 publications

(61 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Myc is an important regulator of cell proliferation and can regulate p27 kip1 levels either transcriptionally (36) or posttranscriptionally (37). We have previously shown that Ad.hPNPase old-35 -mediated or IFN-β-induced hPNPase old-35 protein selectively degrades c-myc mRNA and causes growth arrest at the G 1 to S phase in human melanoma cells (14,15). Our present study reveals another mechanism of p27 kip1 regulation by hPNPase old-35 (i.e., via miR-221 degradation).…”

Section: Discussionmentioning

confidence: 99%

“…Preparation of whole-cell lysates and Western blotting was performed as described previously (15). The primary antibodies included p27 kip1 and hPNPase old-35 from Santa Cruz Biotechnology and MDA-5 from Abcam.…”

Section: Methodsmentioning

confidence: 99%

“…Human polynucleotide phosphorylase (hPNPase old-35 ), a highly evolutionarily conserved gene that catalyzes 3′-to-5′ phosphorolysis as well as 5′-to-3′ polymerization of RNA , acts as a trimer. Analysis of the expression profile of hPNPase old-35 revealed that it is predominantly a type I IFN-inducible gene and might play an essential role in IFN-induced growth arrest in human melanoma cells by executing its exonuclease activity on c-myc mRNA (12)(13)(14)(15). Apart from c-myc mRNA degradation, hPNPase old-35 is also involved in regulating the levels of several small noncoding RNAs (16).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Human polynucleotide phosphorylase selectively and preferentially degrades microRNA-221 in human melanoma cells

Das

Sokhi

Bhutia

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

MicroRNAs (miRNA), small noncoding RNAs, affect a broad range of biological processes, including tumorigenesis, by targeting gene products that directly regulate cell growth. Human polynucleotide phosphorylase (hPNPase old-35 ), a type I IFN-inducible 3′-5′ exoribonuclease, degrades specific mRNAs and small noncoding RNAs. The present study examined the effect of this enzyme on miRNA expression in human melanoma cells. miRNA microarray analysis of human melanoma cells infected with empty adenovirus or with an adenovirus expressing hPNPase old-35 identified miRNAs differentially and specifically regulated by hPNPase old-35 . One of these, miR-221, a regulator of the cyclin-dependent kinase inhibitor p27 kip1 , displayed robust down-regulation with ensuing up-regulation of p27 kip1 by expression of hPNPase old-35 , which also occurred in multiple human melanoma cells upon IFN-β treatment. Using both in vivo immunoprecipitation followed by Northern blotting and RNA degradation assays, we confirm that mature miR-221 is the target of hPNPase old-35 . Inhibition of hPNPase old-35 by shRNA or stable overexpression of miR-221 protected melanoma cells from IFN-β-mediated growth inhibition, accentuating the importance of hPNPase old-35 induction and miR-221 down-regulation in mediating IFN-β action. Moreover, we now uncover a mechanism of miRNA regulation involving selective enzymatic degradation. Targeted overexpression of hPNPase old-35 might provide an effective therapeutic strategy for miR-221-overexpressing and IFN-resistant tumors, such as melanoma.M icroRNAs (miRNAs) are evolutionarily conserved small noncoding RNAs that regulate gene expression at the posttranscriptional level and play important roles in a multiplicity of biological functions, including cell differentiation, tumorigenesis, apoptosis, and metabolism (1). miRNA genes are initially transcribed principally by either RNA polymerase II or RNA polymerase III as long primary transcripts, which are further processed by the nuclear RNase Drosha and cytoplasmic RNase Dicer to produce precursor miRNAs and mature miRNAs, respectively (2). miRNAs recognize and bind to partially complementary sites in the 3′ UTRs of target mRNAs, resulting in either translational repression or target degradation (3). The steadystate levels of miRNAs, crucial for its profound impact on a wide array of biological processes (4, 5), are presumably determined by the opposing activities of miRNA biogenesis and degradation. Although the framework of miRNA biogenesis is established, factors involved in miRNA dysregulation remain unknown. Recent work from Ramachandran and Chen (6) documented that an exoribonuclease encoded by small rna degrading nuclease (sdn) gene degrades mature miRNAs in Arabidopsis. Although in human cells the posttranscriptional control of miRNA is poorly defined, it can be hypothesized that enzymes involved in miRNA metabolism evolved from enzymes that process structural and/or catalytic RNAs, a view supported by the fact that a number of known molecules involved...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Human polynucleotide phosphorylase selectively and preferentially degrades microRNA-221 in human melanoma cells

Das

Sokhi

Bhutia

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…It is well established that IFN-β downregulates c-myc expression (41)(42)(43). Growth and cell proliferation are influenced by c-myc, but it is also known to regulate Cxcr4 (44,45).…”

Section: Figurementioning

confidence: 99%

Neutrophils responsive to endogenous IFN-β regulate tumor angiogenesis and growth in a mouse tumor model

Jabłońska

Leschner²,

Westphal³

et al. 2010

J. Clin. Invest.

480

513

View full text Add to dashboard Cite

Angiogenesis is a hallmark of malignant neoplasias, as the formation of new blood vessels is required for tumors to acquire oxygen and nutrients essential for their continued growth and metastasis. However, the signaling pathways leading to tumor vascularization are not fully understood. Here, using a transplantable mouse tumor model, we have demonstrated that endogenous IFN-β inhibits tumor angiogenesis through repression of genes encoding proangiogenic and homing factors in tumor-infiltrating neutrophils. We determined that IFN-β-deficient mice injected with B16F10 melanoma or MCA205 fibrosarcoma cells developed faster-growing tumors with better-developed blood vessels than did syngeneic control mice. These tumors displayed enhanced infiltration by CD11b + Gr1 + neutrophils expressing elevated levels of the genes encoding the proangiogenic factors VEGF and MMP9 and the homing receptor CXCR4. They also expressed higher levels of the transcription factors c-myc and STAT3, known regulators of VEGF, MMP9, and CXCR4. In vitro, treatment of these tumor-infiltrating neutrophils with low levels of IFN-β restored expression of proangiogenic factors to control levels. Moreover, depletion of these neutrophils inhibited tumor growth in both control and IFN-β-deficient mice. We therefore suggest that constitutively produced endogenous IFN-β is an important mediator of innate tumor surveillance. Further, we believe our data help to explain the therapeutic effect of IFN treatment during the early stages of cancer development.

show abstract

“…IRLB has been shown to bind this sequence, and its molecular cloning has been reported (23). The expression of c-Myc is generally suppressed by IFNs (23)(24)(25)(26), but its transcriptional regulation is not well understood (23).…”

Section: Discussionmentioning

confidence: 99%

Significant induction of apoptosis in renal cell carcinoma cells transfected with cationic multilamellar liposomes containing the human interferon-β gene through activation of the intracellular type 1 interferon signal pathway

et al. 2012

View full text Add to dashboard Cite

Abstract. We previously reported that cationic multilamellar liposome containing the human interferon-β (huIFN-β) gene (IAB-1) demonstrated significant cytotoxic effect in the NC65 human renal cell carcinoma (RCC) cell line. In this study, we investigated the molecular mechanisms of IAB-1-induced apoptosis and cytotoxicity in RCC cells. Remarkable in vitro cytotoxic and apoptosis-inducing effects of IAB-1 against NC65 cells were observed by a colorimetric method and TUNEL staining, respectively. In contrast, treatment of NC65 cells with exogenously added huIFN-β protein induced lowlevel cytotoxicity without apoptosis. Neutralizing antibodies against huIFN-β significantly suppressed the cytotoxic effect of huIFN-β protein, but they were unable to block the effect of IAB-1. Cytotoxicity assays using transwell plates revealed that NC65 cells treated with IAB-1 did not secrete cytotoxic soluble factors other than IFN-β. Substantial enhancement of interferon-stimulated response element (ISRE) activity of NC65 cells by IAB-1 was demonstrated by promoter reporter assays. In addition, immunofluorescence using confocal microscopy revealed the intracellular expression of IFN-β and its receptor induced by IAB-1. The induction of c-Myc by IAB-1 was suggested by a cDNA macroarray and was confirmed by western blot analysis. These findings indicate that IAB-1 induces significant cytotoxicity and apoptosis in NC65 cells, possibly through enhanced ISRE activity, that is associated with increased intracellular localization of huIFN-β and IFN-receptor. Our data support the potential clinical application of IAB-1 gene therapy for RCC resistant to IFN.

show abstract

Defining the mechanism by which IFN-β dowregulates c-myc expression in human melanoma cells: pivotal role for human polynucleotide phosphorylase (hPNPaseold-35)

Cited by 46 publications

References 36 publications

Human polynucleotide phosphorylase selectively and preferentially degrades microRNA-221 in human melanoma cells

Human polynucleotide phosphorylase selectively and preferentially degrades microRNA-221 in human melanoma cells

Neutrophils responsive to endogenous IFN-β regulate tumor angiogenesis and growth in a mouse tumor model

Significant induction of apoptosis in renal cell carcinoma cells transfected with cationic multilamellar liposomes containing the human interferon-β gene through activation of the intracellular type 1 interferon signal pathway

Contact Info

Product

Resources

About