Akt kinases in breast cancer and the results of adjuvant therapy

BACKGROUND: The serine/threonine kinase Akt, or protein kinase B, has recently been a focus of interest because of its activity to inhibit apoptosis. It mediates cell survival by acting as a transducer of signals from growth factor receptors that activate phosphatidylinositol 3-kinase. METHODS: We analysed the expression of the isoforms Akt1 and Akt2 as well as phosphorylated Akt (pAkt) by immunohistochemistry in frozen tumour samples from 280 postmenopausal patients who participated in a randomised trial comparing cyclophosphamide–methotrexate–5-fluorouracil chemotherapy and postoperative radiotherapy. The patients were simultaneously randomised to tamoxifen or to no endocrine treatment. RESULTS: Marked staining was found in 24% of the tumours for Akt1, but in only 4% for Akt2. A low frequency of Akt2-positive cells (1–10%) was observed in another 26% of the tumours. pAkt was significantly associated with both Akt1 and Akt2 expression. Overexpression of erbB2 correlated significantly with pAkt (P = 0.0028). The benefit from tamoxifen was analysed in oestrogen receptor (ER)-positive patients. Patients with a negative status of Akt (no overexpression of Akt1, Akt2 or pAkt) showed significant benefit from tamoxifen. The relative rate of distant recurrence, with versus without tamoxifen, was 0.44 (95% confidence interval [CI], 0.25–0.79) for ER+/Akt1- patients, while it was 0.72 (95% CI, 0.34–1.53) for ER+/Akt1+ patients. The difference in rate ratio did not reach statistical significance. The rate of locoregional recurrence was significantly decreased with radiotherapy versus chemotherapy for Akt-negative patients (rate ratio, 0.23; 95% CI, 0.08–0.67; P = 0.0074), while no benefit was evident for the Akt-positive subgroup (rate ratio, 0.77; 95% CI, 0.31–1.9; P = 0.58). The interaction between Akt and the efficacy of radiotherapy was significant in multivariate analysis (P = 0.042). CONCLUSION: Activation of the Akt pathway is correlated with erbB2 overexpression in breast cancer. The results suggest that Akt may predict the local control benefit from radiotherapy

Factors effecting the induction of rat forestomach hyperplasia induced by Swedish oral smokeless tobacco (snus)

Long term exposure to oral smokeless tobacco may induce lesions in the oral cavity characterized by a hyperplastic epithelium. The possible role of nicotine and the physical properties of oral tobacco for developing these lesions, as well as of dysplasia and neoplasia is unclear. Low nitrosamine Swedish snus as well as non-genotoxic butylated hydroxyanisole induces increased cellular proliferation in the rat forestomach epithelia. Using this model, we report here on the effects of nicotine, pH, and particle size. Snus with different properties had no impact on oxidative stress as determined by 8-oxo-7,8-dihydro-2′-deoxyguanosine, or on interleukin IL-1b. Whereas BHA boosted IL-6, probably due to the presence of nicotine. there was no significant enhancement of cell divisions with increasing particle size, although in individual samples the variations in proliferation rates increased greatly with increasing particle size. Conforming to human experience, the enhanced cell proliferation caused by snus was found to be completely reversible. A cacao bean extract had a protective action similar to that previously found for blueberries. The main cause of the observed tobacco induced cell proliferation could be mechanical irritation, possibly in combination with nicotine, whereas within the studied range, pH did not affect the rate of cell division. © 201

Genotype of metabolic enzymes and the benefit of tamoxifen in postmenopausal breast cancer patients

BACKGROUND: Tamoxifen is widely used as endocrine therapy for oestrogen-receptor-positive breast cancer. However, many of these patients experience recurrence despite tamoxifen therapy by incompletely understood mechanisms. In the present report we propose that tamoxifen resistance may be due to differences in activity of metabolic enzymes as a result of genetic polymorphism. Cytochrome P450 2D6 (CYP2D6) and sulfotransferase 1A1 (SULT1A1) are polymorphic and are involved in the metabolism of tamoxifen. The CYP2D6*4 and SULT1A1*2 genotypes result in decreased enzyme activity. We therefore investigated the genotypes of CYP2D6 and SULT1A1 in 226 breast cancer patients participating in a trial of adjuvant tamoxifen treatment in order to validate the benefit from the therapy. METHODS: The patients were genotyped using PCR followed by cleavage with restriction enzymes. RESULTS: Carriers of the CYP2D6*4 allele demonstrated a decreased risk of recurrence when treated with tamoxifen (relative risk = 0.28, 95% confidence interval = 0.11–0.74, P = 0.0089). A similar pattern was seen among the SULT1A1*1 homozygotes (relative risk = 0.48, 95% confidence interval = 0.21–1.12, P = 0.074). The combination of CYP2D6*4 and/or SULT1A1*1/*1 genotypes comprised 60% of the patients and showed a 62% decreased risk of distant recurrence with tamoxifen (relative risk = 0.38, 95% confidence interval = 0.19–0.74, P = 0.0041). CONCLUSION: The present study suggests that genotype of metabolic enzymes might be useful as a guide for adjuvant endocrine treatment of postmenopausal breast cancer patients. However, results are in contradiction to prior hypotheses and the present sample size is relatively small. Findings therefore need to be confirmed in a larger cohort

The in vitro toxicology of Swedish snus

Three commercial brands of Swedish snus (SWS), an experimental SWS, and the 2S3 reference moist snuff were each tested in four in vitro toxicology assays. These assays were: Salmonella reverse mutation, mouse lymphoma, in vitro micronucleus, and cytotoxicity. Water extractions of each of the 5 products were tested using several different concentrations; the experimental SWS was also extracted using dimethyl sulfoxide (DMSO). Extraction procedures were verified by nicotine determinations. Results for SWS in the mutagenicity assays were broadly negative: there were occasional positive responses, but these were effectively at the highest concentration only (concentrations well above those suggested by regulatory guidelines), and were often associated with cytotoxicity. The 2S3 reference was unequivocally positive in one of the three conditions of the micronucleus assay (MNA), at the highest concentration only. Positive controls produced the expected responses in each assay. The SWS data are contrasted with data reported for combusted tobacco in the form of cigarettes, where strongly positive responses have been routinely reported for mutagenicity and cytotoxicity. These negative findings in a laboratory setting concur with the large amount of epidemiological data from Sweden, data showing that SWS are associated with considerably lower carcinogenic potential when compared with cigarettes