Effect of nephrotoxicants and hepatotoxicants on gene expression profile in human peripheral blood mononuclear cells.

Studying peripheral blood transcriptome in the quest for translational markers of toxicity is considered to be an attractive offshoot in the field of toxicogenomics. Moreover, it is acknowledged that, xenobiotics which cause a toxic response through similar mechanisms lead to distinctive gene expression patterns. The current study was undertaken to gauge the response of an accessible surrogate tissue, such as blood, to drug-induced perturbations aimed at deriving gene expression patterns. Human peripheral blood mononuclear cells (hPBMC) were exposed to conventional drugs, with reported kidney and/or liver injury, in order to determine their transcriptomic response. Test drugs were divided into two classes viz., drugs affecting kidney (cyclophosphamide, amphotericin B, gentamicin and cisplatin) and liver (acetaminophen, rosiglitazone, fluconazole and isoniazid). After performing gene expression analysis and hierarchical clustering, signature patterns for the two classes were obtained, with a set of 365 genes that can discriminate the two classes of drugs. Our results imply that transcriptional profile of hPBMC get altered as a consequence of drug exposure and unique patterns indicative of specific organ toxicity can hence be deduced. These signature patterns obtained for drugs could be studied for their qualification to identify drug-induced toxicity.

NF-κB-mediated anti-inflammatory activity of the sesquiterpene lactone 7-hydroxyfrullanolide.

Microarray technology can be used to study the molecular mechanisms of new chemical entities with the aim to develop effective therapeutics. 7-Hydroxyfrullanolide (7HF) is a sesquiterpene lactone that was found to be efficacious in multiple animal models of inflammation by suppression of pro-inflammatory cytokines; however, its molecular mechanism of action remains unclear. We investigated the effects of 7HF on lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells using microarray-based gene expression studies and explored the molecular targets affected. Gene expression profiles and pathway analysis revealed that 7HF potently suppressed multiple inflammatory pathways induced by LPS. More importantly, 7HF was found to inhibit NF-κB related transcripts. These transcripts were further validated using freshly isolated synovial cells from rheumatoid arthritis patients, thus clinically validating our findings. Cell-based imaging and subsequent Western blot analysis demonstrated that 7HF inhibited the translocation of NF-κB into the nucleus by directly inhibiting the phosphorylation of IKK-ß. Since the transcription of adhesion molecules is regulated by NF-κB, further investigation showed that 7HF dose-dependently suppressed ICAM-1, VCAM-1 and E-selectin expression on LPS-stimulated endothelial cells as well as inhibited the adhesion of monocytes to LPS-stimulated endothelial cells. Taken together, our results reveal that 7HF possesses NF-κB inhibitory potential and suggest a likely molecular mechanism of its anti-inflammatory activity.

Identification of gene expression signature in estrogen receptor positive breast carcinoma.

A significant group of patient with estrogen receptor (ER) α positive breast tumors fails to appreciably respond to endocrine therapy. An increased understanding of the molecular basis of estrogen-mediated signal transduction and resultant gene expression may lead to novel strategies for treating breast cancer. In this study, we sought to identify the dysregulated genes in breast tumors related to ERα status. Microarray analyses of 31 tumor samples showed 108 genes differentially expressed in ERα (+) and ERα (-) primary breast tumors. Further analyses of gene lists indicated that a significant number of dysregulated genes were involved in mRNA transcription and cellular differentiation. The majority of these genes were found to have promoter-binding sites for E74-like factor 5 (ELF5; 54.6% genes), E2F transcription factor 1 (E2F1; 22.2% genes), and nuclear transcription factor Y alpha (NFYA; 32.4% genes). Six candidate genes (NTN4, SLC7A8, MLPH, ENPP1, LAMB2, and PLAT) with differential expression were selected for further validation studies using RT-qPCR (76 clinical specimen) and immunohistochemistry (48 clinical specimen). Our studies indicate significant over-expression of all the six genes in ERα (+) breast tumors as compared to ERα (-) breast tumors. In vitro studies using T-47D breast cancer cell line confirmed the estrogen dependant expression of four of the above six genes (SLC7A8, ENPP1, LAMB2, and PLAT). Collectively, our study provides further insights into the molecular basis of estrogen-dependent breast cancer and identifies "candidate biomarkers" that could be useful for predicting endocrine responsiveness.