Metastatic suppressor CD44 is related with oxidative stress in breast cancer cell lines.

Evidence has accumulated on the role of reactive oxygen species (ROS) in metastasis since surgical removal of tumors generates oxidative stress promoting metastasis and cell growth. Metastasis consists of a cascade of events which allow the cell to survive in target tissues and influence several processes such as dissemination from tumor tissue, transport in blood/lymphatic vessels, invasion and homing of malignant cells. A cDNA oligoarray was used to determine whether alterations of metastatic genes are associated with oxidative stress in breast cancer cell lines. The cell lines used for the experiments were derived from a pre-existent in vitro breast cancer progression model originated in our laboratory. The cDNA array showed alterations in functional gene groups related with cell-cell and cell-matrix interaction molecules, such as caveolin-1; metastasis suppressor genes, such as CD44; metastasis-associated proteases, such as cathepsin D and the protease inhibitor, plasminogen activator inhibitor type 1. The changes of the selected genes were validated by differential display-RT-PCR as well as by protein expression assessed by Western blot analysis. It was found that the cell line, called Tumor2 with down-regulation of basal ROS and manganese superoxide dismutase (MnSOD) expression as a constitutive pattern of this cell line, presented alterations in genes that confer metastatic potential in comparison to the Alpha5 cell line, showing overexpression of basal MnSOD and high levels of ROS. Interesting, it was to found that CD44, considered a metastatic suppressor gene, was influenced by ROS, measured by hydrogen peroxide treatments, as seen by decreased CD44 protein expression in the Alpha5 cell line in a compensatory response to increased MnSOD protein expression. In conclusion, alterations of metastatic genes in malignant breast cancer cell lines were observed in relation to ROS and basal levels of antioxidant enzymes.

Rat lung cancer induced by malathion and estrogen.

Lung cancer can originate from exposure to exogenous and endogenous environmental carcinogens. The use of organophosphorus insecticides has significantly increased in agricultural environments and in urban settings. There is evidence that estrogen can increase lung cancer risk in women. The aim of the present study was to analyze morphological and molecular alterations induced by malathion (M) and 17beta-estradiol (E2) in rat lung tissues. There were four groups: saline solution (control) (100 microg/100 g body weight; BW), M (22 mg/100 g BW), E2 (30 microg/100 gr BW) and combination of both. The animals were injected over a 5-day period and sacrificed 240 days after treatments and lung tissues were excised and analyzed for morphological alterations. Morphometric analysis indicated that M plus E2-treated animals showed a significantly (P<0.05) higher incidence of parenchyma with alveolar proliferative lesions (PAPL), preneoplastic lesions in bronchiolar epithelium (hyperplasia, metaplasia, carcinoma in situ and invasive carcinoma) and atypical lymphatic morphology (lymphatic cell aggregates; LCA) than M or E2 alone-treated and control animals after 240 days. Molecular biology studies indicated that c-ErbB2 and Rho-A had higher protein expression in M plus E2-treated animals in comparison to control and either M- or E-treated animals. In summary, the combination of M and E2 sharply induced pathological lesions in lung alveolar parenchyma, bronchiolar epithelia and lymphatic tissues, in comparison to control animals or in animals treated with either substance alone. These results indicated an increase in risk of rodent lung tumor formation by environmental and endogenous substances.

BigH3 protein expression as a marker for breast cancer.

The current hypothesis of tumorigenesis in humans suggests that cancer cells acquire their hallmarks of malignancy through the accumulation of advantageous gene activation and inactivation events over long periods of time. For breast cancer development, this multistep process may manifest itself as a sequence of pathologically defined stages. It is widely held that breast cancer originates at the premalignant stage of atypical ductal hyperplasia, progresses to the preinvasive stage of ductal carcinoma in situ, and culminates in the potentially lethal stage of invasive ductal carcinoma. Tumor grade has been a highly valuable prognostic factor for breast cancer, and high-grade ductal carcinoma in situ lesions are associated with poor clinical outcome. The aim of this work was to investigate the BigH3 protein expression changes associated with various stages of breast cancer progression in comparison to benign specimens using tissue microarray technology. Pathological characteristics of breast tissues ranged from benign lesions to breast cancers either of lobular or ductal carcinomas in origin, and included in situ ductal carcinomas, lobular carcinomas, infiltrating ductal carcinomas, carcinomas, scirrhous carcinomas, adenocarcinomas and infiltrating colloid carcinomas. BigH3 protein expression was analyzed by immunohistochemistry in 192 cases of breast tumors. Results indicated a decrease in BigH3 protein expression from benign tissues to in situ ductal carcinoma, lobular carcinoma, infiltrating ductal carcinomas, carcinomas, scirrhous carcinoma, adenocarcinomas to infiltrating colloid carcinomas. We observed that the benign tissue had a 23-fold increase in BigH3 protein expression compared to the infiltrating colloid carcinoma which was the most malignant tissue analyzed. In summary, these studies confirmed the suppressor effect of the BigH3 gene expressed as protein expression in those processes related to the progression of breast tumorigenesis. We conclude that this protein can be used as a marker for breast cancer progression.

Gene expression profiling of breast cells induced by X-rays and heavy ions.

Several genetic aberrations and gene expression changes have been shown to occur when cells are exposed to various types of radiation. The integrity of DNA depends upon several processes that include DNA damage recognition and repair, replication, transcription and cell cycle regulation. Ionizing radiation has many sources, including radon decay from the soil and X-rays from medical practice. Epidemiological evidence indicates a risk for cancer by inducing genetic alterations through DNA damage, and molecular alterations have been reported in epidemiological studies of the A-bomb survivors. A spontaneously immortalized human breast epithelial cell model, MCF-10F, was used to examine the gene expression profiling of breast cells induced by X-ray and heavy ion exposure, by a cDNA expression array of DNA damage and repair genes. This cell line was exposed to 10, 50, 100 and 200 cGy of either X-rays or heavy ions and gene expression profiles were studied. Results indicated that out of a total of 161 genes, 38 were differentially expressed by X-ray treatment and 24 by heavy ion (Fe(+2)) treatment. Eight genes were common to both treatments and were confirmed by Northern blot analysis: BRCA1, BIRC2/CIAP1, CENP-E, DDB1, MRE11A, RAD54/ATRX, Wip1 and XPF/ERCC4. A number of candidate genes reported here may be useful molecular biomarkers of radiation exposure in breast cells.