Expression of exogenous NF-IL6 induces apoptosis in Sp2/0-Ag14 myeloma cells

miR-191 promotes tumorigenesis of human colorectal cancer through targeting C/EBPβ

MicroRNA-191 (miR-191), a small non-coding RNA, is involved in disease development and cancer diagnosis and prognosis. However, how miR-191 functions in colorectal cancer remains largely unclear. In this study, we show that miR-191 is highly expressed in colon tumor tissues, and that inhibition of miR-191 leads to decreased cell growth, proliferation and tumorigenicity in a xenograft model. Overexpression of miR-191 in colorectal cancer cell lines alters cell cycle progression and cell resistance to 5-Fu induced cell apoptosis. Mechanistic studies demonstrated that miR-191 directly binds to the 3′UTR of the C/EBPβ mRNA and mediates a decrease in the mRNA and protein expression of C/EBPβ. We further showed that C/EBPβ induces growth arrest in a colorectal cancer cell line and that its expression is negatively correlated with the miR-191 level in patient samples. Our findings suggest that miR-191 may be a potential gene therapy target for the treatment of colorectal cancer.

The effect of environmental chemicals on the tumor microenvironment

Potentially carcinogenic compounds may cause cancer through direct DNA damage or through indirect cellular or physiological effects. To study possible carcinogens, the fields of endocrinology, genetics, epigenetics, medicine, environmental health, toxicology, pharmacology and oncology must be considered. Disruptive chemicals may also contribute to multiple stages of tumor development through effects on the tumor microenvironment. In turn, the tumor microenvironment consists of a complex interaction among blood vessels that feed the tumor, the extracellular matrix that provides structural and biochemical support, signaling molecules that send messages and soluble factors such as cytokines. The tumor microenvironment also consists of many host cellular effectors including multipotent stromal cells/mesenchymal stem cells, fibroblasts, endothelial cell precursors, antigen-presenting cells, lymphocytes and innate immune cells. Carcinogens can influence the tumor microenvironment through effects on epithelial cells, the most common origin of cancer, as well as on stromal cells, extracellular matrix components and immune cells. Here, we review how environmental exposures can perturb the tumor microenvironment. We suggest a role for disrupting chemicals such as nickel chloride, Bisphenol A, butyltins, methylmercury and paraquat as well as more traditional carcinogens, such as radiation, and pharmaceuticals, such as diabetes medications, in the disruption of the tumor microenvironment. Further studies interrogating the role of chemicals and their mixtures in dose-dependent effects on the tumor microenvironment could have important general mechanistic implications for the etiology and prevention of tumorigenesis.

Systemic delivery of full-length C/EBP beta/liposome complex suppresses growth of human colon cancer in nude mice

C/EBP beta (CCAAT/enhancer-binding protein beta) is an important transcription factor involved in cellular proliferation and differentiation. Overexpression of the full-length C/EBP beta protein results in cellular growth arrest and apoptosis. Using a nonviral liposome as carrier, we delivered the full-length C/EBP beta expression plasmid, pCN, into nude mice bearing CW-2 human colon cancer tumors via tail vein. Southern blots revealed that the major organs and tumors were transfected. Experimental gene therapy showed that a strong suppression of tumor growth was observed in the pCN-treated mice, and such suppression was due to the overexpression of C/EBP beta, leading to the increased apoptosis in tumors of pCN-treated mice. No apparent toxic effects of pCN/liposome complex were observed in the animals. Thus, C/EBP beta has tumor suppression effect in vivo and may be used in gene therapy for cancers.

High-dose glucose-insulin-potassium treatment reduces myocardial apoptosis in patients with acute myocardial infarction

BACKGROUND

Several clinical trials have suggested that a metabolic cocktail of glucose-insulin-potassium (GIK) decreases mortality rates in patients with acute myocardial infarction (AMI). It has also been reported that Fas-mediated apoptosis plays an important role in ischaemic/reperfusion injury in the rat model. This study was designed to evaluate the interaction of ischaemic/reperfusion and reperfusion therapy coadministered with high-dose GIK treatment on soluble Fas/APO-1 (sFas) and Fas ligand (sFasL) plasma concentration in patients with AMI.

MATERIALS AND METHODS

Seventy-four patients presenting with AMI who underwent reperfusion therapy were randomized into a GIK group (n = 35) receiving high-dose GIK for 24 h or a vehicle group (n = 39). Thirty-four control subjects were also enrolled in the present study. Strepavidin-biotin ELISA was used to determine the soluble sFas and sFasL plasma concentration at baseline, 24 h (h), 3 day (d), 7 d and 14 d.

RESULTS

Soluble Fas and sFas-L serum concentrations ([sFas] and [sFas-L]) of patients with AMI were significantly elevated at baseline as compared with normal controls (NCs; P < 0.01 vs. NC). The sFas in the GIK and vehicle groups markedly decreased 24 h after the GIK infusion (10.7-->5.9 ng mL(-1) and 9.7-->6.5 ng mL(-1); P < 0.01 vs. baseline) and then increased during the 3-7-d period (5.9-->12.1 ng mL(-1) and 6.5-->11.1 ng mL(-1); P < 0.01 vs. 24 h). The GIK group demonstrated reduced sFas (12.1-->5.9 ng mL(-1)) at 14 d (P < 0.01 vs. 7 d), with no concomitant changes in the vehicle group. The sFas-L in the GIK and vehicle groups was not significant different during the 14-d period.

CONCLUSIONS

These results indicate that the sFas and sFasL in patients with AMI increased significantly compared with NC. Owing to the cardioprotective effects reported here and by others, a high-dose GIK infusion co-administered with the timely re-establishment of nutritive perfusion should be strongly considered as a treatment of choice for AMI. Additionally, sFas may be a valuable marker of the physiological response to ischaemic/reperfusion injury and reperfusion associated with high-dose GIK treatment.

CCAAT/enhancer-binding protein beta plays a regulatory role in differentiation and apoptosis of neuroblastoma cells

The C/EBPbeta (CCAAT/enhancer-binding protein beta) is a transcription factor that belongs to basic region-leucine zipper class DNA-binding proteins. There is a significant body of evidence that suggests that this protein plays a central role in adipocytic and eosinophilic differentiation. However, there is no information available regarding the role of this transcription factor in the development of mammalian neuronal tissues. In this study, we have examined the effect of C/EBPbeta overexpression on the differentiation and survival of mouse Neuro2A cells. We found that C/EBPbeta induces neuronal differentiation and that this process is inhibited by transfection with the C/EBP homologous protein 10 (CHOP), strongly suggesting that the extension of neurites is indeed due to the C/EBPbeta transcriptional activity. As it has been suggested in adipocyte differentiation, here we show that C/EBPbeta induces the expression of the endogenous C/EBPalpha gene and that this protein by itself is also able to induce a differentiated phenotype in Neuro2A cells. Neuronal differentiation induced by C/EBPbeta requires activation of the phosphatidylinositol 3-kinase signaling pathway, whereas inhibition of the mitogen-activated protein kinase signaling does not have any effect. In addition, we show that C/EBPbeta is expressed in the brain of neonatal rats, suggesting that this protein could play an important role in neuronal maturation. Finally, cell death was also induced by C/EBPbeta through activation of the p53 protein and the cdk inhibitor p21.

Glucocorticoid suppression of IGF I transcription in osteoblasts

Glucocorticoids have profound effects on bone formation, decreasing IGF I transcription in osteoblasts, but the mechanisms involved are poorly understood. We previously showed that the bp +34 to +192 region of the rat IGF I exon 1 promoter was responsible for repression of IGF I transcription by cortisol in cultures of osteoblasts from fetal rat calvariae (Ob cells). Here, site-directed mutagenesis was used to show that a binding site for members of the CAAT/enhancer binding protein family of transcription factors, within the +132 to +158 region of the promoter, mediates this glucocorticoid effect. EMSAs demonstrated that cortisol increased binding of osteoblast nuclear proteins to the +132 to +158 region of the IGF I promoter. Supershift assays showed that CAAT/enhancer binding protein alpha, beta, and delta interact with this sequence, and binding of CAAT/enhancer binding protein delta, in particular, was increased in the presence of cortisol. Northern blot analysis showed that CAAT/enhancer binding protein delta and beta transcripts were increased by cortisol in Ob cells. Further, cortisol increased the transcription of these genes and increased the stability of CAAT/enhancer binding protein delta mRNA. In conclusion, cortisol represses IGF I transcription in osteoblasts, and CAAT/enhancer binding proteins appear to play a role in this effect.

Cdkn2a, the cyclin-dependent kinase inhibitor encoding p16INK4a and p19ARF, is a candidate for the plasmacytoma susceptibility locus, Pctr1

Plasma cell tumor induction in mice by pristane is under multigenic control. BALB/c mice are susceptible to tumor development; whereas DBA/2 mice are resistant. Restriction fragment length polymorphisms between BALB/c and DBA/2 for Cdkn2a(p16) and Cdkn2b(p15), and between BALB/c and Mus spretus for Cdkn2c(p18(INK4c)) were used to position these loci with respect to the Pctr1 locus. These cyclin-dependent kinase (CDK) inhibitors mapped to a 6 cM interval of chromosome 4 between Ifna and Tal1. C.D2-Chr 4 congenic strains harboring DBA/2 alleles associated with the Pctr1 locus contained DBA/2 "resistant" alleles of the CDK4/CDK6 inhibitors p16 and p15. On sequencing p16 and p18 cDNAs, two different allelic variants within ankyrin repeat regions of p16 were found between BALB/c and DBA/2 mice. By using an assay involving PCR amplification and restriction enzyme digestion, allelic variants were typed among several inbred strains of mice. One of the variants, G232A, was specific to two inbred strains, BALB/cAn and ABP/Le, of mice and occurred in a highly conserved amino acid in both human and rat p16. When tested with wild-type (DBA/2) p16, both A134C and G232A BALB/c-specific variants of p16 were inefficient in their ability to inhibit the activity of cyclin D2/CDK4 in kinase assays with retinoblastoma protein, suggesting this defective, inherited allele plays an important role in the genetic susceptibility of BALB/c mice for plasmacytoma induction and that p16(INK4a) is a strong candidate for the Pctr1 locus.