MicroRNA changes associated with atypical CYP1A1 inducer BMS-764459

Epigenetic Regulation of Cancer Stem Cells by the Aryl Hydrocarbon Receptor Pathway

Compelling evidence has demonstrated that tumor bulk comprises distinctive subset of cells generally referred as cancer stem cells (CSCs) that have been proposed as a strong sustainer and promoter of tumorigenesis and therapeutic resistance. These distinguished properties of CSCs have raised interest in understanding the molecular mechanisms that govern the maintenance of these cells. Numerous experimental and epidemiological studies have demonstrated that exposure to environmental toxins such as the polycyclic aromatic hydrocarbons (PAHs) is strongly involved in cancer initiation and progression. The PAH-induced carcinogenesis is shown to be mediated through the activation of a cytosolic receptor, aryl hydrocarbon receptor (AhR)/Cytochrome P4501A pathway, suggesting a possible direct link between AhR and CSCs. Several recent studies have investigated the role of AhR in CSCs self-renewal and maintenance, however the molecular mechanisms and particularly the epigenetic regulations of CSCs by the AhR/CYP1A pathway have not been reviewed before. In this review, we first summarize the crosstalk between AhR and cancer genetics, with a particular emphasis on the mechanisms relevant to CSCs such as Wnt/β-catenin, Notch, NF-κB, and PTEN-PI3K/Akt signaling pathways. The second part of this review discusses the recent advances and studies highlighting the epigenetic mechanisms mediated by the AhR/CYP1A pathway that control CSC gene expression, self-renewal, and chemoresistance in various human cancers. Furthermore, the review also sheds light on the importance of targeting the epigenetic pathways as a novel therapeutic approach against CSCs.

Role of miRNA and its potential as a novel diagnostic biomarker in drug-induced liver injury

PURPOSE

MicroRNAs (miRNA or miR) are the most abundant and stable class of small RNA. Unlike the typical RNA molecules present in the cell, they do not encode proteins but can control translation. and Hhence, they are found to play a major role in the regulation of cellular processes. miRNAs have been shown to differentially regulate various genes, and the expression levels of some miRNAs changes several fold in liver and serum, during drug- induced toxicity. This review summarises some of the latest findings about the biological functions of miRNA and its potential use as diagnostic biomarkers in drug- induced liver injury.

METHODS

The information presented in this article is taken from published literature, both original work and reviews on mechanisms of drug- induced liver injury, miRNA in liver pathophysiology, and studies exploring the use of miRNA as biomarker in drug- induced liver injury. Literature search was done using search engines:- PUBMED, Google scholar, and relevant journal sites.

RESULTS AND CONCLUSIONS

Recent research provides insight into the ability of miRNA to regulate various pathways in diseased and nondiseased states of liver. They also lay a foundation for development of diagnostic tests utilizing the potential of miRNAs that can not only be used for early detection of DILI but also to differentiate between different types of DILI. More studies on biological functions of miRNA and standardisation of protocol between research laboratories can lead to further advancement in this field. Considering the therapeutic and diagnostic potential of miRNA, the major challenge would be to integrate these findings to clinical settings where it can be used for the treatment of cases with DILI.

Regulation of Human Cytochrome P4501A1 (hCYP1A1): A Plausible Target for Chemoprevention?

Human cytochrome P450 1A1 (hCYP1A1) has been an object of study due to its role in precarcinogen metabolism; for this reason it is relevant to know more in depth the mechanisms that rule out its expression and activity, which make this enzyme a target for the development of novel chemiopreventive agents. The aim of this work is to review the origin, regulation, and structural and functional characteristics of CYP1A1 letting us understand its role in the bioactivation of precarcinogen and the consequences of its modulation in other physiological processes, as well as guide us in the study of this important protein.