OT1-03-03: Effect of Tamoxifen Therapy on Inhibition of Tumor Suppressor p53 by Estrogen Receptor

Background: A large number of patients with estrogen receptor (ER)-positive tumors are resistant to tamoxifen (TAM). Although several plausible reasons for such resistance have been suggested, the mechanisms remain unclear. ER mediates effects of estrogen by promoting proliferation of breast cancer cells. Tumor suppressor protein p53 guards against tumorigenesis by preventing proliferation of cells with genomic damage. Dr. Das's laboratory previously reported that ER binds and functionally suppresses wild type p53 in human breast cancer cells and xenograft tumor tissue, and TAM is capable of inhibiting this interaction. We hypothesize that relieving suppression of wild type p53 by ER could be an important mechanism underlying TAM action in breast cancer. To test this hypothesis, we have initiated a pilot randomized clinical trial of 50 women with newly diagnosed ERa-positive breast cancer.

Specific Aims: 1) To investigate the effect of a short pre-surgical intervention with TAM on the ER-p53 interaction in ER-positive, p53 wild type breast tumors and 2) To confirm the wild type status of p53 and analyze the functional status of the p53 pathway by monitoring expression of selected p53 target genes in tumors that have and have not been treated with TAM.

Trial design: A randomized clinical trial in the pre-surgical setting was proposed with either TAM 20mg for four weeks vs. no intervention. Patients randomized to the TAM arm will undergo multiple pharmacokinetic and phamacodynamic measurements of TAM metabolites and genotyping for common polymorphisms of TAM metabolism genes, CYP2D6 and CYP3A4/5. Fresh tumor tissue will be harvested from all patients at the time of surgery for analysis of ER-p53 protein interaction using tissue chromatin immunoprecipitation (tissue ChIP) assay. p53 gene status will be determined by sequencing. RNA and protein expression of ER, p53, and a selected group of ER and p53 target genes in the diagnostic core biopsy and surgical specimens will be analyzed by quantitative real-time PCR (qRTPCR) and immunohistochemistry (IHC). TAM metabolites will also be measured in the tumor and the surrounding benign tissue.

Eligibility criteria: Women greater or equal to eighteen years of age diagnosed with ER-positive invasive breast cancer (approximately 1cm in size) who will undergo primary surgical excision for their initial therapy are eligible. Women must not be pregnant, be on current hormonal therapy, or have a history of hypercoagulable syndrome or prior arterial or venous thrombosis.

Statistical methods: Descriptive statistics such as frequencies and relative frequencies will be computed for all categorical variables. Numeric variables will be summarized using simple descriptive statistics such as mean, standard deviation, and quartiles. Ninety-five percent confidence intervals will be computed. ChIP data will be subjected to Fisher's Exact Test. IHC date will be analyzed by Wilcoxon-Mann-Whitney test.

Present accrual and target accrual: We have accrued 17 patients to date and plan to accrue a total of 50 patients, 25 in each arm.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-03-03.

Functional expression of an acyl carrier protein (ACP) from Azospirillum brasilense alters fatty acid profiles in Escherichia coli and Brassica juncea

Acyl carrier protein (ACP) is a central cofactor for de novo fatty acid synthesis, acyl chain modification and chain-length termination during lipid biosynthesis in living organisms. Although the structural and functional organization of the ACPs in bacteria and plant are highly conserved, the individual ACP is engaged in the generation of sets of signature fatty acids required for specific purpose in bacterial cells and plant tissues. Realizing the fact that the bacterial ACP being originated early in molecular evolution is characteristically different from the plant's counterpart, we explored the property of an ACP from Azospirillum brasilense (Ab), a plant-associative aerobic bacterium, to find its role in changing the fatty acid profile in heterologous systems. Functional expression of Ab-ACP in Escherichia coli, an enteric bacterium, and Brassica juncea, an oil-seed crop plant, altered the fatty acid composition having predominantly 18-carbon acyl pool, reflecting the intrinsic nature of the ACP from A. brasilense which usually has C18:1 rich membrane lipid. In transgenic Brassica the prime increment was found for C18:3 in leaves; and C18:1 and C8:2 in seeds. Interestingly, the seed oil quality of the transgenic Brassica potentially improved for edible purposes, particularly with respect to the enhancement in the ratio of monounsaturated (C18:1)/saturated fatty acids, increment in the ratio of linoleic (C18:2)/linolenic (C18:3) and reduction of erucic acid (C22:1).

Characterisation of PM(10), PM(2.5) and benzene soluble organic fraction of particulate matter in an urban area of Kolkata, India

In this study, the relationship between inhalable particulate (PM(10)), fine particulate (PM(2.5)), coarse particles (PM(2.5 - 10)) and meteorological parameters such as temperature, relative humidity, solar radiation, wind speed were statistically analyzed and modelled for urban area of Kolkata during winter months of 2003-2004. Ambient air quality was monitored with a sampling frequency of twenty-four hours at three monitoring sites located near traffic intersections and in an industrial area. The monitoring sites were located 3-5 m above ground near highly trafficked and congested areas. The 24 h average PM(10) and PM(2.5) samples were collected using Thermo-Andersen high volume samplers and exposed filter papers were extracted and analysed for benzene soluble organic fraction. The ratios between PM(2.5) and PM(10) were found to be in the range of 0.6 to 0.92 and the highest ratio was found in the most polluted urban site. Statistical analysis has shown a strong positive correlation between PM(10) and PM(2.5) and inverse correlation was observed between particulate matter (PM(10) and PM(2.5)) and wind speed. Statistical analysis of air quality data shows that PM(10) and PM(2.5) are showing poor correlation with temperature, relative humidity and solar radiation. Regression equations for PM(10) and PM(2.5) and meteorological parameters were developed. The organic fraction of particulate matter soluble in benzene is an indication of poly aromatic hydrocarbon (PAH) concentration present in particulate matter. The relationship between the benzene soluble organic fraction (BSOF) of inhalable particulate (PM(10)) and fine particulate (PM(2.5)) were analysed for urban area of Kolkata. Significant positive correlation was observed between benzene soluble organic fraction of PM(10) (BSM10) and benzene soluble organic fraction of PM(2.5) (BSM2.5). Regression equations for BSM10 and BSM2.5 were developed.

Measurements of inhalable particles<10 microm (PM(10)) and total suspended particulates (TSP) concentrations along the north-south corridor, in Kolkata, India

The 24-hour concentrations of total suspended particulate matter (TSP) and respirable suspended particulates (PM(10)) were monitored during March 2003 to February 2004 from a network of 15 sampling stations along a populated urban corridor of Kolkata City in India. The air samplers were placed at a distance 20-200 m from roadways and their height from ground level was within 3 to 5 m. It was also insured that from any obstacle to the airflow was at least 30 cm away. Over the study area, the monthly average concentrations of TSP and PM(10) were found to be 200.3 +/-93.1 microg/m(3) and 95.8+/-67.5 microg/m(3), respectively, while the 24-hour average concentrations were in the range of 17--456 microg/m(3) and 15--291 microg/m(3), respectively. The higher average values at particular stations reflected the closeness of those to heavy road traffic. With regards to the temporal variations, higher concentrations were observed during winter and lower concentrations during monsoon. Statistical analysis of the sampling data was conducted to obtain general characteristics of the particulate pollution and to investigate the effects of traffic volume and meteorological factors on the pollution level. TSP and PM(10) concentrations were found to be highly correlated with each other at all the sampling stations. There were clear associations between TSP and PM(10) data set at all the measured 15 stations and on average, PM(10) was 52% of the total TSP concentration.

Bovine chymosin: production by rDNA technology and application in cheese manufacture

Bovine chymosin, an aspartyl protease extracted from abomasum of suckling calves, is synthesized in vivo as preprochymosin and secreted as prochymosin which is autocatalytically activated to chymosin. Chymosin is bilobular, with Asp 32 and Asp 215 acting as the catalytic residues. Chymosin A and chymosin B have pH optima of 4.2 and 3.8, respectively, and act to initiate milk clotting by cleaving kappa-casein between Phe 105 and Met 106. The gene encoding chymosin has been cloned and expressed in suitable bacteria and yeast hosts under the control of lac, trp, trp-beta, gly A genes, and serine hydroxymethyl-transferase promoters. Protein engineering of chymosin has also been attempted. A number of companies are now producing recombinant chymosin for commercial use in cheese manufacture.

Cloning, characterization, and expression studies in Escherichia coli of growth hormone cDNAs from Indian zebu cattle, reverine buffalo, and beetal goat

The growth hormone cDNAs from three different economically important animal species of indian origin viz., indian zebu cattle (Bos indicus), indian reverine buffalo (Bubalus bubalis), and beetal goat (Capra hircus) were isolated by the RT-PCR technique. The amplified product was then cloned into phagemid pBluescriptIIKS- and the nucleotide sequence of the entire 573 base coding region for each product was determined. The genetic sequences as well as the translated protein sequence of these ruminant species were compared to that of closely related species like taurine cattle (Bos taurus) and sheep (Ovis aries). A very high degree of nucleotide sequence homology, ranging between 97-98%, was observed. Subsequently, the buffalo and goat cDNAs were used for expression studies in Escherichia coli. Very low levels of expression resulted when the growth hormone cDNAs were directly placed under the strong E. coli (trc) or phage (T7) promoters with the approximate level being less than 0.1% and 1% of the intracellular E. coli proteins, respectively. The nearly 10-fold enhancement of the level of expression as observed was attributable to the nature of the untranslated leader sequence donated by the individual expression element. High level (about 20% of soluble E. coli protein) expression of buffalo/goat growth hormone was achieved as a fusion protein with glutathione-s-transferase (GST) in pGEX-KT. Further, although attempts at converting the GST-GH fusion protein system to a two-cistronic gene expression system were unsuccessful, the utilization of a short synthetic first cistron in the two-cistronic mode of expression resulted in high levels (approximately 30% of soluble protein cell fraction) of GH polypeptide with a native N-terminus in E. coli for all three cDNAs.