Cytoplasmic PML promotes TGF-ß-associated epithelial-mesenchymal transition and invasion in prostate cancer.

Epithelial-mesenchymal transition (EMT) is a key event that is involved in the invasion and dissemination of cancer cells. Although typically considered as having tumour-suppressive properties, transforming growth factor (TGF)-ß signalling is altered during cancer and has been associated with the invasion of cancer cells and metastasis. In this study, we report a previously unknown role for the cytoplasmic promyelocytic leukaemia (cPML) tumour suppressor in TGF-ß signalling-induced regulation of prostate cancer-associated EMT and invasion. We demonstrate that cPML promotes a mesenchymal phenotype and increases the invasiveness of prostate cancer cells. This event is associated with activation of TGF-ß canonical signalling pathway through the induction of Sma and Mad related family 2 and 3 (SMAD2 and SMAD3) phosphorylation. Furthermore, the cytoplasmic localization of promyelocytic leukaemia (PML) is mediated by its nuclear export in a chromosomal maintenance 1 (CRM1)-dependent manner. This was clinically tested in prostate cancer tissue and shown that cytoplasmic PML and CRM1 co-expression correlates with reduced disease-specific survival. In summary, we provide evidence of dysfunctional TGF-ß signalling occurring at an early stage in prostate cancer. We show that this disease pathway is mediated by cPML and CRM1 and results in a more aggressive cancer cell phenotype. We propose that the targeting of this pathway could be therapeutically exploited for clinical benefit.

Expression and effects of modulation of the K2P potassium channels TREK-1 (KCNK2) and TREK-2 (KCNK10) in the normal human ovary and epithelial ovarian cancer.

PURPOSE: Aberrant expression of potassium (K(+)) channels contributes to cancer cell proliferation and apoptosis, and K(+) channel blockers can inhibit cell proliferation. TREK-1 and -2 belong to the two-pore domain (K2P) superfamily. We report TREK-1 and -2 expression in ovarian cancer and normal ovaries, and the effects of TREK-1 modulators on cell proliferation and apoptosis. METHODS: The cellular localisation of TREK-1 and -2 was investigated by immunofluorescence in SKOV-3 and OVCAR-3 cell lines and in cultured ovarian surface epithelium and cancer. Channel expression in normal ovaries and cancer was quantified by western blotting. Immunohistochemical analysis demonstrated the association between channel expression and disease prognosis, stage, and grade. TREK-1 modulation of cell proliferation in the cell lines was investigated with the MTS-assay and the effect on apoptosis determined using flow cytometry. RESULTS: Expression was identified in both cell lines, ovarian cancer (n = 22) and normal ovaries (n = 6). IHC demonstrated positive staining for TREK-1 and -2 in 95.7 % of tumours (n = 69) and 100 % of normal ovaries (n = 9). A reduction in cell proliferation (P < 0.05) was demonstrated at 96 h in SKOV-3 and OVCAR-3 cells incubated TREK-1 modulating agents. Curcumin caused a significant reduction in early apoptosis in SKOV-3 (P < 0.001) and OVCAR-3 (P < 0.0001) cells and a significant increase in late apoptosis in SKOV-3 (P < 0.01) and OVCAR-3 cells (P < 0.0001). CONCLUSIONS: TREK-1 and -2 are expressed in normal ovaries and ovarian cancer. TREK-1 modulators have a significant effect on cell proliferation and apoptosis. We propose investigation of the therapeutic potential of TREK-1 blockers is warranted.

Primary liver cancer and aflatoxin intake in Transkei.

Transkei has an intermediate primary liver cancer (PLC) rate that is unusually high for a corn-based subsistence economy. The situation is complicated by a very high esophageal carcinoma incidence rate and known exposure to hepatocarcinogenic N-nitrosamines. A total of 623 cooked food samples were collected from two northeastern and two southern districts over two seasons, in a single-sample grid pattern, for aflatoxin analysis. Aflatoxin B1 was quantitated in 26% of all samples during 1976, resulting in a mean contamination rate of 0.65 microgram/kg wet food. Mean contamination during 1977 was 0.66 microgram/kg, and 24% of samples were positive. Thus for both years a mean aflatoxin B1 intake of 16.5 ng/kg body weight per day was calculated. When the data were plotted on our published PLC incidence-aflatoxin intake graph constructed with standardized data from four countries, Transkei was well within the 95% confidence limits. Individual district comparisons are handicapped by as yet inadequate PLC incidence data, but rank order correlations (rs) between aflatoxin intakes and the PLC incidence in goldminers originating from the study districts were significant (P less than .05). Corn was the basis of 95% of the meals and was also the main source of contamination. Six of 23 samples of home-brewed corn beer were positive for aflatoxin, resulting in an overall contamination of 0.69 microgram/L.

A field outbreak of suspected stachybotryotoxicosis in sheep.

An outbreak of mortality in a flock of mutton merino sheep in which 109 out of 568 sheep died in the south-western Cape Province, is described. It was characterized by haemorrhagic septicaemia, anaemia, leucocytopaenia and haemorrhagic tendencies. Mortalities followed unseasonal and heavy summer rain, extended over a period of 6 months and were associated with the uninterrupted consumption of sheep cubes processed on the farm severly fungus-infested wheat, barley and rye straw for a period of at least one month. The main clinical signs occurred in two phases: an elevated body temperature, listlessness, epistaxis and intermittent haemorrhagic diarrhoea during the first phase of the outbreak, and a progressively worsening anaemia, leucocytopaenia and less severe haemorrhagic tendencies and a terminally elevated body temperature during the second phase. The predominant autopsy findings were purpuric haemorrhage on serosal and mucosal surfaces and in most of the organs, enterorrhagia and severe pulmonary congestion and oedema during the first stage; anaemia was the predominant sign during the second stage - widespread haemorrhage still occurred but was less extensive. Pasteurella haemolytica was isolated from most of the animals autopsied during the first stage. Histologically the most salient features were atrophy and necrosis of the lymphoid tissue, aplastic anaemia and a markedly impaired inflammatory response. Extensive post-natal lamb mortalities, probably due to an Escherichia coli infection precipitated by the toxicosis, occurred during the outbreak. Toxigenic strains of Stachybotrys chartarum were isolated from the wheat and barley straw. Diethyl ether extracts of the wheat straw, sheep cubes and S. chartarum culture material elicited positive skin tests in rats following intradermal injection and the presence of 12,13-epoxytrichothecenes in these extracts were confirmed by thin layer chromatography. In feeding trials sheep cubes and wheat straw caused the death of 4/4 one-day-old Pekin ducklings and weanling Wistar rats in six and nine days, respectively. This is the first description of an outbreak of disease in sheep associated with the ingestion of S. chartarum-infested food components in the Republic of South Africa.

Isolation and purification of moniliformin.

A bulk purification procedure is described for moniliformin, a mycotoxin produced by Fusarium moniliforme. The method involves methanol extraction of suitably molded maize, aqueous extraction of the methanol-free residue, ion exchange chromatography with a NaCl concentration gradient, desalination, and crystallization. A pKa value of 1.70 as well as molar absorptivities of 19100 (lambda (H2O) max 229 nm), 5600 (lambda (H2O) max 260 nm), and 4700 (lambda (MeOH) max 260 nm) L/mole/cm are reported for moniliformin.

New species of Aspergillus producing sterigmatocystin.

A number of species belonging to the genus Aspergillus were evaluated for their toxicity to ducklings and the ability to produce sterigmatocystin. Three new species capable of producing sterigmatocystin were found, namely, Aspergillus aurantio-brunneus, Aspergillus quadrilineatus, and Aspergillus ustus. All three were toxic to ducklings. The production of sterigmatocystin by Aspergillus rugulosus was confirmed, and the toxicity of Aspergillus stellatus and Aspergillus multicolor is described.