[New insights in oncology: epigenetics and cancer stem cells]

Gene Expression Profiling of Hepatocellular Carcinoma Derived Cancer Stem Like Cell under Hypoxia

PURPOSE

Cancer stem like cells (CSCs), with unlimited self-renewal potential and other stem cell characteristics, occur in several cancers including hepatocellular carcinoma (HCC). Although CSCs can initiate tumors, malignant proliferation, relapse and multi-drug resistance, the ways how to activate them still remain unknown. This study aims to evaluate whether CSC acquire tumorigenic characters under tumor hypoxia, analyzed by microarray analysis.

MATERIALS AND METHODS

CSCs were purified from HCC patients and Affymetrix microarray was used to investigate their gene expression profiles. The results were validated by real-time polymerase chain reaction (PCR).

RESULTS

The results of the microarray indicated that 18 genes were up-regulated and 10 genes were down-regulated in CSCs. Several genes were identified to be significantly involved in the regulation of CSCs such as HCC. Furthermore, the up-regulated genes were related with metabolism, angiogenesis and hypoxia, whereas the down-regulated genes were related with apoptosis and inflammation.

CONCLUSION

The results may help to understand the mechanisms of tumor development through CSCs which acquired their distinctive tumorogenic properties by hypoxic stimulation.

miRNAs regulate stem cell self-renewal and differentiation

Stem cells undergo symmetric and asymmetric divisions to generate differentiated cells and more stem cells. The balance between self-renewal and differentiation of stem cells is controlled by transcription factors, epigenetic regulatory networks, and microRNAs (miRNAs). Herein the miRNA involvement in the regulation of stem cell self-renewal and differentiation is summarized. miRNA contribution to malignancy through regulating cancer stem cells is described. In addition, the reciprocal associations between miRNAs and epigenetic modifications in control of stem cell fate are discussed.

Nicotinamide, NAD(P)(H), and Methyl-Group Homeostasis Evolved and Became a Determinant of Ageing Diseases: Hypotheses and Lessons from Pellagra

Compartmentalized redox faults are common to ageing diseases. Dietary constituents are catabolized to NAD(H) donating electrons producing proton-based bioenergy in coevolved, cross-species and cross-organ networks. Nicotinamide and NAD deficiency from poor diet or high expenditure causes pellagra, an ageing and dementing disorder with lost robustness to infection and stress. Nicotinamide and stress induce Nicotinamide-N-methyltransferase (NNMT) improving choline retention but consume methyl groups. High NNMT activity is linked to Parkinson's, cancers, and diseases of affluence. Optimising nicotinamide and choline/methyl group availability is important for brain development and increased during our evolution raising metabolic and methylome ceilings through dietary/metabolic symbiotic means but strict energy constraints remain and life-history tradeoffs are the rule. An optimal energy, NAD and methyl group supply, avoiding hypo and hyper-vitaminoses nicotinamide and choline, is important to healthy ageing and avoids utilising double-edged symbionts or uncontrolled autophagy or reversions to fermentation reactions in inflammatory and cancerous tissue that all redistribute NAD(P)(H), but incur high allostatic costs.