Induction of apoptotic cell death by IFNbeta on HPV-16 transformed human keratinocytes

Promotion of TRAIL/Apo2L-induced apoptosis by low-dose interferon-β in human malignant melanoma cells

Interferon β (IFN-β) is considered a signaling molecule with important therapeutic potential in cancer since IFN-β-induced gene transcription mediates antiproliferation and cell death induction. Whereas, TNF-related apoptosis inducing ligand/Apo2 ligand (TRAIL/Apo2L) has emerged as a promising anticancer agent because it induces apoptosis specifically in cancer cells. In this study, we elucidated that IFN-β augments TRAIL-induced apoptosis synergistically using five human malignant melanoma cells. All of these cells were induced apoptosis by TRAIL. Whereas, the response against IFN-β was different in amelanotic cells (A375 and CRL1579) and melanotic cells (G361, SK-MEL-28, and MeWo). The responsibility of amelanotic cells against IFN-β was higher than those of melanotic cells. The synergism of IFN-β and TRAIL were correlated with the responsibilities of the cells against IFN-β. The synergistic interaction was confirmed by a combination index based on the Chou-Talalay method. The upregulation of apoptosis in amelanotic cells was caused by very low doses of IFN-β (over 0.1 IU/ml). Both of p53-mediated intrinsic pathway and Fas-related extrinsic pathway were activated by IFN-β alone and combination with TRAIL. Further, TRAIL death receptors (DR4 and DR5) were upregulated by a low-dose IFN-β (over 0.1 IU/ml) and the expression was more promoted by the combination with TRAIL. It was clarified that the upregulation of DR5 is associated with the declination of viability.

Type 1 IFN inhibits the growth factor deprived apoptosis of cultured human aortic endothelial cells and protects the cells from chemically induced oxidative cytotoxicity

It has been shown that the genesis of atherosclerotic lesions is resulted from the injury of vascular endothelial cells and the cell damage is triggered by oxygen radicals generated from various tissues. Human vascular endothelial cells can survive and proliferate depending on growth factors such as VEGF or basic FGF and are induced apoptosis by the deprivation of growth factor or serum. It was found that type 1 IFN inhibits the growth factor deprived cell death of human aortic endothelial cells (HAEC) and protects the cells from chemically induced oxidative cytotoxicity. The anti-apoptotic effects of type 1 IFN were certified by flow cytometry using annexin-V-FITC/PI double staining and cell cycle analysis, fluorescence microscopy using Hoechst33342 and PI, colorimetric assay for caspase-3 activity, p53 and bax mRNA expressions, and cell counts. It was considered that IFN-β inhibits the executive late stage apoptosis from the results of annexin-V-FITC/PI double staining and the inhibition of caspase-3 activity, and that the anti-apoptotic effect might be owing to the direct inhibition of the apoptotic pathway mediated by p53 from the transient down-regulation of bax mRNA expression. Whereas, type 1 IFN protected the cells from the oxidative cytotoxicity induced by tertiary butylhydroperoxide (TBH) under the presence of Ca(2+). The effects of IFN-β is more potent inhibitor of cell death than IFN-α. These results indicate that type 1 IFN, especially IFN-β may be useful for the diseases with vascular endothelium damage such as atherosclerosis or restenosis after angioplasty as a medical treatment or a prophylactic.

Local expression of interferon-alpha and interferon receptors in cervical intraepithelial neoplasia

PURPOSE

The present study evaluated mRNA expression of interferon-alpha (IFN-alpha), IFN-alpha receptor subunits (IFNAR-1 and IFNAR-2) and an IFN-stimulated gene encoding the enzyme 2',5'-oligoadenylate synthetase (2'5'OAS) in biopsies on patients with varying grades of cervical intraepithelial neoplasia (CIN I, II and III).

METHODS

Uterine cervix biopsies were collected from women with CIN I, II and III (n = 28) and controls without CIN lesions or human papilloma virus (HPV) infection (n = 17). The presence of high and low-risk HPV DNA was determined using hybrid capture. The mRNA levels of IFNAR-1, IFNAR-2, IFN-alpha and 2'5'OAS were determined by RT-PCR with specific primers.

RESULTS

The control group exhibited a greater frequency of IFNAR-1 expression (10/17; 58.3%) than the CIN samples (4/28; 14.2%) (P = 0.0018), while, the expression of IFNAR-2 was also greater in the control samples (11/17; 64.7%) than in the patients with lesions (2/28; 7.1%) (P = 0.0018). Importantly, simultaneous expression of both receptors was observed only in the control group (8/17; 47.0%) (P = 0.0001). Among the CIN samples, there was one case of low expression of mRNA of IFNAR-1 and IFNAR-2. IFN-alpha was present in 14.2% (4/28) of the CIN samples but was not expressed in the control group. mRNA 2'5'OAS were expressed in 28.5% (8/28) of the CIN samples and 11.7% (2/17) of the control samples (not statistically significant). Fifty percent (14/28) of the CIN samples were positive for HPV DNA.

CONCLUSIONS

Cervical biopsy samples from control women or those without neoplasia or HPV infection displayed higher IFN-alpha receptor expression than those with CIN, while simultaneous expression of both IFN-alpha receptor subunits was found only in the control group. There was no significant difference in mRNA expression of IFN-alpha and 2'5'OAS between the control and CIN groups. Then we concluded that the samples obtained from patients with CIN present low levels of the IFN-alpha receptor mRNA.

IFN-beta induces caspase-mediated apoptosis by disrupting mitochondria in human advanced stage colon cancer cell lines

Various human colon cancer cell lines tested in vitro differed significantly in susceptibility to growth inhibition of recombinant human interferon-beta (rHuIFN-beta). Two p53-mutant lines, COH and CC-M2, derived from high-grade colon adenocarcinoma, showed signs of apoptosis after treatment with 250 IU/ml of HuIFN- beta in the culture medium. The similarly p53-mutated HT-29 line from a grade I adenocarcinoma showed no apoptosis, however, and only cell cycle G1/G0 or S phase retardation with 1000 IU/ml HuIFN-beta. After HuIFN-beta exposure, COH and CC-M2 cells showed increased levels of Fas and FasL proteins, alteration of mitochondrial membrane potential, and activation of caspase-9, caspase-8, and caspase-3 in a time-dependent manner. Treatment of COH and CC-M2 cells with anti-FasL antibodies or rFas/Fc fusion protein, however, could not prevent the apoptosis induced by HuIFN-beta. In contrast, cell-permeable specific inhibitors of the three caspases could inhibit the DNA fragmentation and cell death but not the mitochondrial membrane potential changes. Treatment with mitochondria-stabilizing reagents could significantly abrogate the apoptosis and caspase activation induced by HuIFN-beta. These results suggest that in COH and CC-M2 colon cancer cell lines, HuIFN-beta induces apoptosis mainly through mitochondrial membrane alteration and subsequent activation of the caspase cascade pathway, but not by the Fas/FasL interaction or the p53-dependent apoptotic mechanism.

Interferons and apoptosis

The interferons (IFNs), in addition to their well-known antiviral activities, have important roles in the control of cell proliferation and are effective agents for the treatment of a limited number of malignant diseases. IFNs not only regulate cell growth and division but also influence cell survival through their effects on apoptosis. This review describes the current state of knowledge about the mechanisms of action of these cytokines on the apoptotic machinery, with particular emphasis on the synergism that exists between the IFNs and other proapoptotic agents, such as members of the tumor necrosis factor (TNF) family. The review also discusses the physiologic and clinical implications of the effects of the IFNs on apoptosis for regulation of viral infection and tumor growth.

Immortalization of human cells and their malignant conversion by high risk human papillomavirus genotypes

Papillomaviruses cause certain common human cancers, most notably carcinoma of the cervix. The viral oncoproteins E6 and E7 are essential components in malignant conversion, although, in spite of being necessary, they are not sufficient for the development of the malignant phenotype. High risk HPV oncogenes fulfill dual functions in genome-harboring cells: their derived oncoproteins stimulate cell growth by pleiotropic effects. At the same time they act as progression factors by inducing mutations in host cell DNA and aneuploidy. The mechanism underlying the process towards malignant conversion, usually covering a long latency period between primary infection and cancer emergence, is presently not fully understood. It emerges, however, that cancer development depends on the interruption of at least two signalling cascades (labeled as CIF I and CIF II) that interfere with the function of viral oncoproteins (CIF I) and with the transcription of viral oncogenes (CIF II). Further modifications of host cell genes most likely mediate the escape from immune surveillance mechanisms of the host and the development of metastases.