Recombinant human GM-CSF enhances the anti-proliferative activity of vitamin D in MCF-7 human breast cancer clonogenic cells

1alpha,25-Dihydroxyvitamin D(3) inhibits rat liver ultrastructural changes and the development of gamma-glutamyltranspeptidase-positive foci in diethylnitrosamine-initiated and streptozotocin-induced diabetes-promoted hepatocarcinogenesis

In the present study, the chemopreventive effect of the active metabolite of vitamin D, 1alpha,25-dihydroxyvitamin D(3) (VD(3)), against chemically-induced and diabetes-promoted rat liver carcinogenesis was investigated. Hepatocarcinogenesis was initiated with a single intraperitoneal (i.p.) injection of diethylnitrosamine (DEN) (125 mg kg(-1) body weight) at week 4 followed by promotion with streptozotocin (STZ) (65 mg kg(-1) body weight with a single i.p. injection) at week 7. With this basic experimental regimen, the effect of VD(3) (0.3 microg (0.1 ml)(-1) propylene glycol per os twice a week) was investigated with effect from 4 weeks prior to the exposure of DEN. The results showed that VD(3) supplementation throughout the experimental period reduced the incidence, total number and multiplicity and altered the size of visible persistent nodules (PNs) in DEN- or DEN + STZ-treated rats as compared with their respective controls. In these two groups, it also caused a significant decrease in the number (p < 0.002 and 0.001 respectively) and focal area (p < 0.05) of gamma-glutamyltranspeptidase (GGT)-positive hepatic foci. Moreover, continuous supplementation of VD(3) exhibits a protective effect in maintaining the normal cellular architecture of the hepatocytes in DEN- or DEN + STZ-treated rats. Our results thus strongly suggest that VD(3) is very effective in the inhibition of DEN-initiated and STZ-induced diabetes-promoted rat liver carcinogenesis.

Inhibitory effect of vitamin D3 on 3'methyl-4-dimethyl-amino-azobenzene-induced rat hepatocarcinogenesis: a study on antioxidant defense enzymes

The anticarcinogenic effect of vitamin D3 (VD3) on 3,-methyl-4-dimethyl-amino-azobenzene (3,-Met-DAB)-induced hepatocarcinogenesis was investigated in male Sprague-Dawley rats. Anticancer efficacy of VD3 was estimated using different possible biomarkers, namely reduced glutathione (GSH) concentration, gamma-glutamyl transpeptidase (GGT) activity, glutathione S-transferase (GST) activity, glutathione reductase (GRd) activity, glutathione peroxidase (GPx) activity in hyperplastic nodules (HNs) and non-nodular surrounding parenchyma (NNSP) liver areas. VD3 was found to control the carcinogen-induced alterations in GSH level, GST, GGT, GRd and GPx activity both in HNs and NNSP liver areas during long-term exposure. A decrease in the number of HNs was also evident in the present investigation. VD3 was proved to be an effective antitumor drug during the initiation/promotion phases of hepatic carcinogenesis but the effect was found to be less prominent during initiation and promotion phases.

Anticlastogenic potential of 1alpha,25-dihydroxyvitamin D3 in murine lymphoma

Vitamin D3, having gained scientific interest for so long because of its role in mineral homeostasis, has now received great importance as a possible antitumor agent. This study was undertaken in an attempt to visualize the possible anticlastogenic potential of the vitamin in an ascitic mouse lymphoma model namely, Dalton's lymphoma. Frequencies of structural type chromosomal aberrations, sister chromatid exchanges and micronucleus assays have been chosen as the genotoxic endpoints in the proposed investigation. All these cytogenetic markers have been found to be markedly elevated during the progression of lymphoma in bone marrow cells. Vitamin D3 effectively suppressed the frequencies of chromosomal aberrations and sister chromatid exchanges in the lymphoma-bearing mice during the entire phase of tumor growth that significantly coupled with almost two-fold increase in survival time (37 +/- 2 and 68 +/- 2 days in lymphoma controls and vitamin D3-treated lymphoma-bearing mice, respectively), thus substantiating the antineoplastic efficacy of this secosteroid. The outcome of this study also is clearly reflected in the depletion of circulating (serum) vitamin D3 levels in the lymphoma control mice compared with normal (vehicle) controls while a still higher level was maintained in the VD3-treated lymphoma mice. This anticlastogenic property of the vitamin has so far been neglected and this is the first attempt to unravel the vitamin D3's effect in combating tumor development in vivo by limiting the frequencies of chromosomal aberrations, sister chromatid exchanges and micronuclei at least in transplantable murine model studied herein.

Induction of the c-myc but not the cH-ras promoter by platinum compounds

The recombinant plasmids p324, p330 and p323 carrying the aminoglycoside phosphotransferase (aph) gene and 5' flanking c-myc sequences linked to the reporter gene chloramphenicol acetyl-transferase (cat) were introduced into the mouse erythroleukaemic cell line F412B2TK- and stable transfectants resistant to geneticin G418 were obtained. The effects of cis-platin and two novel platinum compounds, D19466 (lobaplatin) and D17872, on c-myc promoter regions were studied using a large range of drug concentrations and correlated with cytotoxicity data. It was found that cis-platin and D19466 show a similar pattern of cytotoxicity and activation of c-myc promoter-driven cat gene expression with maximum effect (increased expression of 7.4- and 8.1-fold, respectively) at a concentration of 5 x 10(-5) M, while the less cytotoxic D17872 only slightly activates cat expression at the same concentration. However, when the F412B2TK- cell line was transfected with a plasmid carrying 5' flanking sequences of the c-Hras1 gene with promoter/enhancer function, linked to the cat reporter, no similar inductive effect was observed with any of the platinum drugs used. These data suggest that platinum compounds and possibly other DNA-damaging agents may specifically influence the expression of certain genes.