MGMT gene silencing by promoter hypermethylation in gastric cancer in a high incidence area

Purpose

Inactivation of tumor suppressor and DNA repair genes by promoter hypermethylation does commonly occur in human cancers. O⁶-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes methyl groups as well as larger adducts at the O⁶ position of guanine. In the absence of MGMT activity, O⁶-methylguanine mispairs with thymine during DNA replication, resulting in G:C to A:T transitions. Promoter hypermethylation of the MGMT gene has been observed in various cancers, including gastric cancer. Here, we aimed at assessing the promoter hypermethylation, mutation and expression status of the MGMT gene in patients from a geographic region with a high incidence of gastric cancer (Kashmir, North India) and to investigate their association with various clinicopathological characteristics.

Methods

In this study 82 gastric cancer samples and adjacent normal tissues were included. Mutations in the MGMT gene were detected by single stranded conformational polymorphism (SSCP) analysis and direct sequencing. Methylation-specific polymerase chain reaction (MS-PCR) and Western blot analyses were performed to detect promoter hypermethylation and concomitant (loss of) expression of the MGMT gene.

Results

Promoter hypermethylation of the MGMT gene was found in 52.44 % (43 of 82) of the tumor samples and loss of MGMT protein expression was detected in 45.12 % (37 of 82) of the tumor samples. Hypermethylation and loss of expression were significantly associated with higher tumor grades (moderately/poorly differentiated) (P?P?MGMT hypermethylation and loss of expression were found to be significantly associated with high salt tea consumption (P?Conclusions Our results indicate that MGMT promoter hypermethylation and concomitant loss of MGMT protein expression may play an important role in the development of gastric cancer in the Kashmiri population. High salt tea consumption may be a risk factor.     

A regulatory SNP of the BICD1 gene contributes to telomere length variation in humans

Telomeres are repetitive sequences of variable length at the ends of chromosomes involved in maintaining their integrity. Telomere dysfunction is associated with increased risk of cancer and other age-related diseases. Telomere length is an important determinant of telomere function and has a strong genetic basis. We previously carried out a genome-wide linkage analysis of mean leukocyte telomere length, and identified a 12 cm quantitative-trait locus affecting telomere length on human chromosome 12. In the present study we confirmed linkage to this locus in an extended sample (380 families, 520 sib-pairs, maximum LOD score 4.3). Fine-mapping identified a 51 kb region of association within intron 1 of the Bicaudal-D homolog 1 (BICD1, MIM 602204) gene. The strongest association (P = 1.9 x 10(-5)) was with SNP rs2630578 where the minor allele C (frequency 0.21) was associated with telomeres that were shorter by 604 (+/-204) base pairs, equivalent to approximately 15-20 years of age-related attrition in telomere length. Subjects carrying the C allele for rs2630778 had 44% lower BICD1 mRNA levels in their leukocytes compared with GG homozygotes (P = 0.004). BICD1 is involved in Golgi-to-endoplasmic reticulum vacuolar transport. Previous studies have implicated vacuolar genes in telomere length homeostasis in yeast. Our study indicates that BICD1 plays a similar role in humans.     

New butyrylcholinesterase inhibitory steroid and peroxy acid from Leucas urticifolia

A new steroid leucisterol (1) and a new peroxy acid urticic acid (2) along with methoxybenzyl benzoate (3), 4-hydroxy benzoic acid (4), beta-sitosterol (5), and ursolic acid (6), have been isolated from the chloroform soluble fraction of the whole plant of Leucas urticifolia. Their structures were elucidated on the basis of nuclear magnetic resonance (1D and 2D NMR) spectral data. Leucisterol showed potent inhibitory activity against butyrylcholinesterase enzyme.     

New aromatic esters from Galinsoga parviflora

Galinosoates A-C (1-3), new aromatic esters, have been isolated from the n-hexane soluble fraction of Galinsoga parviflora. Their structures were assigned from the spectral data including IR, HR-EI-MS, 1D and 2D NMR.     

Term delivery of the second twin after miscarriage of the first: a case report

BACKGROUND: Term delivery of the second twin after miscarriage of the first twin is rare. There is always a risk of preterm delivery as well as infection leading to chorioamnionitis. CASE: The second twin was delivered at term after miscarriage of the first twin at 17 weeks'gestation. The pregnancy was carefully monitored for prevention and early detection of chorioamnionitis. Delivery was delayed to 30 weeks after the miscarriage of the first twin, with a good outcome. CONCLUSION: Delayed delivery of the second twin with conservative management clearly is of benefit.     

Identification of type-specific anticancer histone deacetylase inhibitors: road to success

Cancer is a serious and life-eliminating disease. Majority of anticancer agents are non-selective. Along with the cancerous cells they also target the normal ones. An important aspect is to hit the developing mechanism of the tumor, which is highlighted by in silico drug designing. On the basis of novel molecular targets, in silico (computational approach) drug discovery has emerged as today’s need. Histone deacetylases are an important therapeutic target for many human cancers. The first and only approved (in 2006) histone deacetylase inhibitors (HDACIs) is Zolinza. Depending on the types of the histone deacetylase (HDAC) enzymes, discovery of type-specific inhibitors is important. With continued research and development, in near future HDACIs are likely to figure prominently in cancer treatment plans. This review presents the overview of HDACs, their role in cancer, their structural classes, activity, catalytic domain and the inhibitors of HDACs for cancer therapy. Also it helps in understanding the open directions in this area of research and highlights the importance of computational approaches in discovering specific drugs for cancer therapy.     

Apoptosis‐inducing and Antitumor Activity of Neolignans Isolated from Magnolia officinalis in HeLa Cancer Cells

Two neolignans, 4′‐methoxymagndialdehyde (1) and magnaldehyde B (2), were isolated from the stem bark of Magnolia officinalis (Magnoliaceae), evaluated for apoptosis‐inducing effects in human cervical epitheloid carcinoma HeLa cells. The apoptosis‐inducing activity of compounds 1 and 2 were assessed by DNA content using flow cytometric analysis. In the immunoblotting analysis, the treatment with 1 and 2 resulted in the cleavage of procaspase‐8 and ‐3 and poly(ADP‐ribose)polymerase into active forms. In addition, in vivo, the administration of 2 to Lewis lung carcinoma‐inoculated mice evidenced a significant inhibition of tumor growth (volume) with reduction of 28.7% at concentration of 20 mg/kg, as compared with the control mice. These findings suggest that 2 can inhibit the proliferation of tumor cells, and might be an anti‐tumoric agent. Copyright © 2012 John Wiley & Sons, Ltd.     

In vivo investigation of estrogen regulation of adrenal and renal angiotensin (AT1) receptor expression by PET.

The renin angiotensin system (RAS) has been implicated as one mediator of the cardiovascular effects of estrogen. Since changes in angiotensin type 1 (AT(1)) receptor expression are central to modulation of the RAS, we used the noninvasive PET imaging technique to study for the in vivo effects of estrogen on membrane and intracellular AT(1) receptors. METHODS: Dynamic PET measurements of canine AT(1) (cAT(1)) receptors using the radiolabeled AT(1) receptor antagonist, (11)C-L-159,884, were performed during 2-wk consecutive periods of estrogen deprivation induced by ovariectomy and 17beta-estradiol (E(2)) replacement. RESULTS: Kinetic modeling of time-activity curves in the kidney and adrenal showed lower receptor expression in the estrogen replete state (21% and 30% decrease in Gjedde-Patlak slope, influx constant, respectively). These in vivo findings correlated with in vitro radioligand-binding assays with (125)I-[Sar(1),Ile(8)]angiotensin II showing reduced AT(1) receptor number in the adrenal (35%), glomeruli (30%), myocardium (35%), and liver (21%) in the estrogen-replenished compared with estrogen-depleted animals. CONCLUSION: Although other endogenous systems are known to regulate AT(1) receptors and could compete with estrogenic actions, these PET studies reveal that estrogen attenuates AT(1) receptor expression in vivo. Thus, estrogen modulation of AT(1) receptors may contribute to the cardiovascular protective effects associated with estrogen.