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M R Banerjee

Publications and source records attributed to M R Banerjee.

At least 19 recordsLinked to original sources
PubMed1992

beta-Carotene-mediated inhibition of a DNA adduct induced by 7,12-dimethylbenz(a)anthracene and 7-hydroxymethyl-12-methylbenz(a)anthracene in mouse mammary gland in vitro.

The influence of beta-carotene on the formation of DNA-adducts induced by 7,12-dimethylbenz(a)anthracene (DMBA) and 7-hydroxymethyl-12-methylbenz(a)anthracene (7-OHM-12-MBA) during transformation of mouse mammary cells in organ culture was analysed. Treatment with beta-carotene (10(-8)-10(-5) mol/l) caused inhibition (48.8-94.4%) of an adduct (VI), which was detectable in DNA samples from DMBA-treated mammary glands. Out of six adducts, derived from further analysis of DNA samples from 7-OHM-12-MBA-treated glands, adduct f eluted in the same fraction as adduct (VI), indicating these adducts were analogous. Likewise, adduct f was also inhibited by beta-carotene. Boronate chromatographic analysis revealed this particular adduct was a syn-dihydrodiol epoxide product. Adduct inhibition was detectable both at the start and after DMBA treatment. alpha-Tocopherol and canthaxanthin were ineffective in inhibiting adducts. It is reasonable to conclude that beta-carotene-mediated modification of adducts is associated with the inhibition of a syn-adduct, which is derived from further metabolism of a 7-OHM-12-MBA intermediate.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Neoplastic transformation and DNA damage of mouse mammary epithelial cells by N-methyl-N'-nitrosourea in organ culture.

An appropriate in vitro system was used to study the effect of a direct-acting carcinogen on the transformation of mammary epithelial cells in the organ culture of the whole mammary gland in vitro. Studies were done to determine the ability of N-methyl-N'-nitrosourea (MNU) to transform the mammary cells in organ culture. Mouse mammary glands were treated with single or multiple doses of MNU during various periods of the culture. To assay for neoplastic transformation potential of MNU on mammary cells, mammary glands were dissociated and the cells were injected into the parenchyma-free inguinal mammary fat pad of syngeneic virgin female host mice. Palpable tumors were observed in injected glands of 23% of the mice after 3-4 months and an additional 31% showed serially transplantable hyperplastic alveolar nodules (HANs). Histopathologic examination of the tissues showed that the tumors were mammary adenocarcinoma. All tumors and hyperplasias were secondarily transplanted into syngeneic animals, resulting in tumors and hyperplasias of similar histopathology. In addition, DNA damage of the epithelial cells in organ culture caused by MNU was also measurable using the new nick translation assay. The most extensive DNA damage occurred when the glands were treated on day 4 and day 5 of the mammogenic culture period. These results demonstrate that the mouse mammary epithelial cells are susceptible to the carcinogenic action of the direct-acting carcinogen MNU and that the whole mammary gland-culture system offers an appropriate in vitro model for studying the mechanism of carcinogenesis induced by MNU.

Animals↗
PubMed1990

Acute effects of atrial natriuretic peptide on lung mechanics and hemodynamics in awake sheep.

The purpose of this study was to measure airway and hemodynamic effects of atrial natriuretic peptide (ANP) and its efficacy in counteracting the changes in lung mechanics that occur with aerosol histamine and carbachol. Synthetic human alpha-ANP was injected into the pulmonary arteries of awake sheep chronically instrumented for measurement of lung mechanics and hemodynamics (n = 7). Base-line dynamic lung compliance (Cdyn) and pulmonary resistance (RL) did not change after ANP injection. On separate days, the dose required to reduce Cdyn to 65% of base line (ED65Cdyn) to progressive doses of aerosol histamine and the dose required to increase RL by 100% of the base-line values (ED200RL) to progressive doses of aerosol carbachol were determined. ANP was given as bolus injections of 1, 5, and 10 micrograms/kg 3 min after either the ED65Cdyn or ED200RL doses of histamine and carbachol, respectively, and the airway response was monitored for 10 min. ANP significantly reversed the rise in RL after carbachol administration (n = 10). This action of ANP was not altered by cyclooxygenase inhibition with ibuprofen. ANP did not reverse the reduction in Cdyn caused by either histamine (n = 7) or carbachol. The bronchodilating effect of ANP appears to be more prominent in the larger central airways than in the peripheral airways. The hemodynamic effects of ANP were similar to those reported by others. Heart rate and cardiac output had a biphasic response, with an initial rise followed by a drop below the base line. Systemic arterial and left atrial pressures decreased significantly. Pulmonary arterial pressure did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗
PubMed1989

Fate of 7,12-dimethylbenz(a)anthracene in the mouse mammary gland during initiation and promotion stages of carcinogenesis in vitro.

Metabolic conversion and distribution of the products of 7,12-dimethylbenz(a)anthracene (DMBA) were analyzed in the mouse mammary cell transformation model in organ culture. In order to determine the levels of uptake of DMBA, the glands were exposed to the transforming dosage of the procarcinogen (7.8 microM, 20 microCi/ml) for 24 h, and the level of uptake was determined to be 8 x 10(4) cpm/mg of tissue. Subsequently, the glands were incubated in DMBA-free medium, and distribution of the radioactivity in DNA and in the acid-insoluble materials was measured. Data showed that, in addition to the 24-h DMBA treatment period, the initiation stage extends for another 3 h when the incubation is continued in DMBA-free medium. A saturation level of uptake of [3H]DMBA into the whole gland was observed at 12 h, while DMBA was continually metabolized with the products being bound to DNA and to the acid-insoluble fractions throughout the entire incubation period with or without DMBA. The three major adducts identified were anti-DMBA-3,4-diol-1,2-epoxide (DMBADE):deoxyguanosine, syn-DMBADE:deoxyadenosine, and anti-DMBADE:deoxyadenosine. Qualitatively the adduct profiles remained similar. However, with the additional 3-h incubation in DMBA-free medium, the three major DMBA-DNA adducts increased slightly by 6.5 to 7.5%. Thus the total 27-h time period can be considered as the duration of the initiation stage in the DMBA-induced carcinogenesis of mouse mammary cells in organ culture. Therefore the subsequent 6-h incubation in DMBA-free medium may be considered as within the promotional stage, and at the same time period the levels of the three DNA adducts decreased significantly by 67.5 to 84.1% (P less than 0.001).

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Influence of some dietary chemopreventive agents on the expression of functional differentiation of the mouse mammary gland in vitro.

The purpose of the present studies was to determine the influence of the chemopreventive agents selenium, 4-(hydroxyphenyl)-retinamide (4-HPR) and beta-carotene, on functional differentiation (lactogenesis) of the mouse mammary gland cells. The hormone-induced expression of the milk-protein genes, beta-casein, epsilon-casein and the whey acidic protein (WAP) was used as molecular marker of differentiation of the mammary cells in organ culture medium containing insulin, prolactin, aldosterone and hydrocortisone. Quantitative determination of the cellular concentration of the respective mRNA was ascertained by molecular hybridization of RNA to the specific cloned cDNA probes using both the solution and the filter hybridization methods. Selenium at 100 nm concentration caused a pronounced inhibition of accumulation of the respective mRNAs. The retinoid, 4-HPR, also caused a dose-dependent inhibition of expression of these mRNA sequences. In contrast, concentrations of the 3 mRNAs in beta-carotene-treated glands remained similar to those observed in glands cultured in medium containing the hormones and hexane (the latter being the solvent for beta-carotene). The significant antagonistic action of selenium and 4-HPR, however, was reversible after removal of the chemicals from the culture medium. Thus, among the 3 chemicals tested, selenium and retinoid can cause an adverse effect on functional differentiation (lactogenesis) of the mammary cells. This inhibitory effect, however, was reversible. beta-Carotene, on the other hand, caused no apparent antagonistic effect on expression of the milk-protein genes in the isolated whole mammary organ in culture.

Actins↗
PubMed1987

Metabolism of 7,12-dimethylbenz[a]anthracene by mouse mammary cells in serum-free organ culture medium.

The murine mammary gland is a prime target organ for 7,12-dimethylbenz[a]anthracene, (DMBA)-induced carcinogenesis. We analyzed the metabolism of 3H-DMBA in a cell-free microsomal activation system derived from mouse mammary microsomes and in a whole mammary organs in culture. The in vitro microsomal activation system failed to show the more polar diol derivative of DMBA after HPLC. The metabolites obtained directly from the 3H-DMBA-treated whole mammary organs, however, revealed the presence of both the diol as well as the phenolic derivatives of DMBA. Analysis of the glands and the culture medium further showed that nearly 95% of the radioactivity added to the culture medium was associated with the adipose tissue and complete solubilization of the fat pad released substantial amounts of DMBA and its metabolites. It appears that a large portion of DMBA and its metabolites remain entrapped in the adipose tissue surrounding the parenchyma. Formic acid digestion of the gland releases the DMBA and the metabolites allowing their ethylacetate extraction, and HPLC characterization.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

DMBA induced DNA damage and repair in mammary epithelial cells in vitro measured by a nick translation assay.

A new E. coli DNA polymerase I directed nick translation assay was used for measuring 7,12-dimethylbenz[a]anthracene-induced in situ DNA damage and repair in mouse mammary epithelial cells in monolayer culture. The nick translation assay was capable of detecting a DMBA-dose dependent significant increase of DNA damage, and the same assay also allowed monitoring of the DNA repair activity provoked by DMBA treatment of the epithelial cells. This relatively simple method thus provides a rapid assay for carcinogen-induced in situ DNA damage and repair in an epithelial cell tumorigenic system.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1985

A generally applicable improved method for preparation of single stranded cDNA probes from clones constructed in M13 vectors.

A generally applicable simplified procedure for the preparation of radiolabeled cDNA hybridization probes from cDNA clones in M13 (M13mp8) bacteriophage vectors is described. A cDNA copy of the insert DNA is synthesized by controlled reaction with the Klenow fragment of E. coli DNA polymerase I, primed with oligo-dT or sequencing primer. The cDNA is separated from the recombinant phage DNA template by alkaline gel electrophoresis. Sensitivity of the cDNAs was tested by quantitative measurement of specific mRNAs in solution hybridization under RNA (R0t analysis) or cDNA (RNA titration) excess conditions. The procedure permits measurement of mRNA levels as small as 0.00001-0.00006% in total RNA preparation. Cellular accumulation of hormone-induced mRNAs for the milk proteins, whey acidic protein and epsilon-casein was also measured using the cDNAs.

Animals↗
PubMed1985

beta-Carotene reduces sister chromatid exchanges induced by chemical carcinogens in mouse mammary cells in organ culture.

Present studies in the mammary epithelial cell transformation model in organ culture showed that presence of beta-carotene during the 24 hr treatment (initiation stage) of the glands with the carcinogens, 7,12-dimethylbenz[a]anthracene (DMBA), N-nitrosodiethylamine (DENA) and N-methylnitrosourea (MNU), caused a highly significant (P less than 0.001-0.01) reduction of SCE induced by the same carcinogens. In contrast, 4-hydroxyphenyl retinamide (4-HPR) which is known to act at the promotional stage of carcinogenesis did not show any significant reduction of SCE. Thus findings suggest that beta-carotene can modify the DNA damaging effect of the carcinogens and thereby may also prevent the initiation of the carcinogenic process.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

Glucocorticoid modulation of prolactin receptors on mammary cells of lactating mice.

Prolactin receptors were monitored by measuring 125I-labeled prolactin binding to collagenase-dissociated mammary epithelial cells of lactating BALB/c mice. Specific receptors for iodine-labeled prolactin with an apparent dissociation constant (Kd) of 0.99 . 10(-9) M were present on the dissociated mammary cells. The binding was inhibited by ovine prolactin, human growth hormone and human placental lactogen but not by follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, bovine growth hormone or insulin. Adrenal ablation of nursing mothers caused a reduction of the number of prolactin receptors and this effect was preventable by hydrocortisone therapy. Hydrocortisone injections to mothers 3 days after adrenalectomy also induced a replenishment of the prolactin receptors on the mammary cells. Injections of progesterone failed to sustain the high level of mammary cell prolactin receptors in adrenalectomized animals. Stimultaneous injections of hydrocortisone and progesterone to animals 3 days after adrenalectomy caused a partial suppression of the stimulatory action of hydrocortisone alone. The results suggest that hydrocortisone can exert a modulatory influence on mammary cell prolactin receptors in non-hypophysectomized post-partum mice without altering the dissociation constant (Kd) of the receptors.

Adrenal Glands↗
PubMed1979

Neoplastic transformation of epithelial cells in whole mammary gland in vitro.

Biological characteristics of nodule-like alveolar lesions (NLAL) induced by 7,12-dimethylbenz[a]anthracene (DMBA) in organ culture of whole mammary gland (BALB/c female mice) were assessed after transplantation into gland-free mammary fat pads of syngeneic virgin mice. (i) Tissue-fragment explants from NLAL areas of the gland produced abnormal lobuloalveolar (LA) outgrowths in 3 of 10 fat pads. (ii) Transplantation of dissociated cells of NLAL-derived LA outgrowths into 36 fat pads showed 100% LA outgrowths and 3 (8%) of these 36 outgrowths produced mammary carcinomas. (iii) The explants of dissociated cells from whole mammary glands treated with DMBA in culture produced full or partial LA structures in 2 of 56 outgrowths. (iv) The explants of dissociated cells prepared from outgrowths derived from outgrowths derived from explants as in iii produced 9 LA outgrowths in 16 instances; mammary tumor incidence in these outgrowths was 3 of 16 (18%). (v) The explants of tissue fragments from LA outgrowths as in iv produced LA outgrowths in 20 of 20 fat pads; mammary carcinomas appeared in 16 of 20 (80%) of these outgrowths. No NLAL was detectable in control glands treated with dimethyl sulfoxide (solvent for DMBA); explants of the control glands consistently produced ductal outgrowths and no tumor. This accomplishment of chemical carcinogen-induced neoplastic transformation of epithelial cells in vitro provides a model for studying carcinogenesis in an entire isolated organ.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

Glucocorticoid modulation of casein gene transcription in mouse mammary gland.

The influence of cortisol and prolactin on casein gene expression in the mammary gland of lactating BALB/c mice was measured by using a specific cDNA probe to 15S casein mRNA (cDNAcsn). Casein mRNA (mRNAcsn) level in the mammary gland was decreased by 85% 5 days after adrenal ablation, but then was increased 4.4-fold 12 hr after a single injection of hydrocortisone-21-acetate. An 80% decrease in serum prolactin level, induced by the prolactin inhibitor 2-bromo-alpha-ergocryptin (CB-154), did not alter the level of mRNAcsn in the gland. Specific transcription of the casein gene in nuclei isolated from lactating mammary glands was measured by cDNAcsn hybridization to the in vitro synthesized Hg-CTP-containing RNA (Hg-RNA), which was purified by SH-agarose chromatography. The level of the mRNAcsn in Hg-RNA synthesized in the isolated nuclei was 0.09% and this was decreased 85% by alpha-amanitin, indicating that the mRNAcsn sequences in the Hg-RNA were the products of RNA polymerase II-directed DNA-dependent RNA synthesis. Transcription of the mRNAcsn in isolated nuclei was decreased by 70% 5 days after adrenalectomy and a single injection of the glucocorticoid then increased the transcription level 2-fold at 6 hr. Essentially no alteration of the level of transcription was detectable in mammary nuclei isolated from lactating mice with 80% decreased serum prolactin level, induced by CB-154 treatment. The results thus demonstrate a glucocorticoid involvement on the modulation of casein gene expression at the transcriptional level of control.

Adrenalectomy↗
PubMed1979

The influence of chromatin structure on the distribution of DNA repair synthesis studied by nuclease digestion.

The influence of chromatin structure on the distribution of DNA repair synthesis was studied by enzymatic digestion of "repair labeled" nuclei of mouse mammary cells: "repair labeled" nuclei were isolated from pregnancy mammary tissue fragments, treated in vitro with methylmethanesulfonate (MMS) or methylnitrosourea (MNU), and pulse-labeled with 3H-thymidine in the presence of hydroxyurea in the culture medium. Micrococcal nuclease digestion of "repair labeled" nuclei indicates that at early hours after treatment with the alkylating agents 70-80% of the total repair synthesis is located in the linker portion of the nucleosome. However, 6-12 hours after treatment DNA repair synthesis is more evenly distributed throughout the core and linker portion of the nucleosome. "Repair labeled" mammary cell nuclei were also digested with DNase I under conditions selective for transcriptionally active chromatin. A two-fold higher level of repair synthesis was found in the transcriptionally active chromatin of "repair labeled" nuclei isolated from MMS or MNU treated mammary fragments, pulse-labeled at different times after treatment. The results indicate that structural constitution of the chromatin may influence the distribution of DNA repair synthesis both at the nucleosome level, and at higher levels of chromatin organization. This may be due to 1) nonrandom base alkylation in chromatin or 2) areas in chromatin with increased accessibility for the repair enzymes to the alkylated bases.

Animals↗
PubMed1978

Prolactin receptor on dissociated mammary epithelial cells at different stages of development.

Properties of prolactin receptors were measured by monitoring [125I]prolactin binding to specific receptor sites on collagenase-dissociated mammary epithelial cells of virgin, pregnant and lactating mice. On a Scatchard plot the data generated a straight line and the estimated dissociation constant (Kd) and number of receptor sites on lactating cells were 0.9 x 10(-9) and 1540 per cell. The [125I]prolactin binding was inhibited in presence of unlabeled prolactin and other lactogenic polypeptide hormones, but not by nonlactogenic polypeptide hormones. The [125I]prolactin binding was sensitive to pronase and trypsin but not to DNAase, RNAase and hyaluronidase. Scatchard plot analysis further showed that while the number of receptors on mammary cells was variable at different stages of endocrine regulated developmental changes of the gland, Kd of the hormone--receptor complex generally remained similar. The high level of prolactin receptors on mammary cells of virgins was reduced during pregnancy and the lactating mammary cells showed a highly elevated level of prolactin receptors. The results demonstrate that specific prolactin receptors can be measured on collagenase dissociated mammary epithelial cells and this method permits a direct assessment of the number of receptors on a per cell basis rather than indirect estimates, based on average DNA or protein content of the tissue, composed of heterogeneous cell types.

Animals↗
PubMed1978

RNA synthesis in isolated nuclei of lactating mammary cells in presence of unmodified and mercury-labeled CTP.

Isolated nuclei of lactating mouse mammary gland were capable of supporting DNA-dependent RNA synthesis in vitro in presence of unmodified and mercurated CTP (Hg-CTP) at high ionic condition at 25 degrees C. In presence of unmodified CTP, [3H]UMP incorporation into RNA increased linearly upto 180 min. The kinetic pattern of the reaction and the rate of RNA synthesis were essentially similar when CTP was replaced by Hg-CTP. Both in unmodified and Hg-CTP containing reactions, 70-80% of RNA synthesis was inhibited by alpha-amanitin. Presence of poly(A) in a small portion of the in vitro synthesized messenger-like RNA was detectable by oligo(dT) cellulose chromatography. Both poly(A)+ and poly(A)- RNAs sedimented with a clear peak around 15S region in a formamide-sucrose denaturing gradient. The Hg-RNA after separation from endogenous nuclear RNA by SH-agarose affinity column chromatography also sedimented around 15S region in a formamide-sucrose gradient. The Hg-RNA synthesized in the isolated mammary cell nuclei in vitro should now permit monitoring hormonal regulation of specific gene (casein) transcription in the mammary cells by molecular hybridization of the Hg-RNA with cDNA to casein mRNA.

Amanitins↗