Effects of Nicotine Doses and Administration Frequencies on Mouse Body Weight and Adipose Tissues.

INTRODUCTION: This study investigates the effects of varying nicotine doses and administration frequencies on mouse body weight, adipose tissues, and liver. METHODS: Male C57BL6/J mice received subcutaneous nicotine doses (0.5mg/kg, 1mg/kg, or 2mg/kg) once daily (qd), twice daily (bid), or four times daily (qid) for 4 weeks. Body weight, inguinal white adipose tissue (iWAT), epididymal white adipose tissue (eWAT), brown adipose tissue (BAT) weight and size, and UCP1 expression were assessed, along with liver fat deposition and morphology. RESULTS: Nicotine administration reduced body weight and decreased the weight and size of iWAT and eWAT compared to controls. The frequency of nicotine administration had a more significant impact on body weight and fat tissues than the dosage itself, with 2mg/kg bid being optimal for weight reduction. Nicotine increased BAT cell numbers and amplified UCP1 expression in iWAT and BAT. It had minor effects on eWAT UCP1 expression and no substantial impact on liver fat deposition or morphology, except for a reduction in liver weight with doses exceeding 4mg/kg. CONCLUSIONS: Nicotine-induced weight reduction is frequency-dependent, with 2mg/kg bid being the optimal regimen. The mechanisms may include reductions in iWAT and eWAT weights and cell sizes, induction of browning in iWAT, increased BAT quantity and UCP1 expression, and heightened energy expenditure in iWAT and BAT. Nicotine's ability to induce eWAT browning is relatively weak, indicating diverse mechanisms of action across different adipose tissue types. These findings provide a foundation for further exploration of nicotine's multifaceted functions and underlying mechanisms. IMPLICATIONS: This study examines how different nicotine doses and administration frequencies affect mouse body weight and adipose tissues. It finds that administering nicotine bid (twice daily) at 2mg/kg leads to optimal weight reduction. Nicotine induces browning in white adipose tissue, increases brown adipose tissue quantity and UCP1 expression, and affects energy expenditure. The findings underscore nicotine's nuanced effects across different adipose tissue types and lay groundwork for further exploration of its mechanisms and therapeutic potential in weight management.

Epigenetic Activation of Cytochrome P450 1A2 Sensitizes Hepatocellular Carcinoma Cells to Sorafenib.

Cytochrome P450 1A2 (CYP1A2) is a known tumor suppressor in hepatocellular carcinoma (HCC), but its expression is repressed in HCC and the underlying mechanism is unclear. In this study, we investigated the epigenetic mechanisms of CYP1A2 repression and potential therapeutic implications. In HCC tumor tissues, the methylation rates of CYP1A2 CpG island (CGI) and DNA methyltransferase (DNMT) 3A protein levels were significantly higher, and there was a clear negative correlation between DNMT3A and CYP1A2 protein expression. Knockdown of DNMT3A by siRNA significantly increased CYP1A2 expression in HCC cells. Additionally, treating HCC cells with decitabine (DAC) resulted in a dose-dependent upregulation of CYP1A2 expression by reducing the methylation level of CYP1A2 CGI. Furthermore, we observed a decreased enrichment of H3K27Ac in the promoter region of CYP1A2 in HCC tissues. Treatment with the trichostatin A (TSA) restored CYP1A2 expression in HCC cells by increasing H3K27Ac levels in the CYP1A2 promoter region. Importantly, combination treatment of sorafenib with DAC or TSA resulted in a leftward shift of the dose-response curve, lower IC50 values, and reduced colony numbers in HCC cells. Our findings suggest that hypermethylation of the CGI at the promoter, mediated by the high expression of DNMT3A, and hypoacetylation of H3K27 in the CYP1A2 promoter region, leads to CYP1A2 repression in HCC. Epigenetic drugs DAC and TSA increase HCC cell sensitivity to sorafenib by restoring CYP1A2 expression. Our study provides new insights into the epigenetic regulation of CYP1A2 in HCC and highlights the potential of epigenetic drugs as a therapeutic approach for HCC. SIGNIFICANCE STATEMENT: This study marks the first exploration of the epigenetic mechanisms underlying cytochrome P450 (CYP) 1A2 suppression in hepatocellular carcinoma (HCC). Our findings reveal that heightened DNA methyltransferase expression induces hypermethylation of the CpG island at the promoter, coupled with diminished H3K27Ac levels, resulting in the repression of CYP1A2 in HCC. The use of epigenetic drugs such as decitabine and trichostatin A emerges as a novel therapeutic avenue, demonstrating their potential to restore CYP1A2 expression and enhance sorafenib sensitivity in HCC cells.

SMART v1.0: A Database for Small Molecules with Functional Implications in Plants.

We developed SMART v1.0 ( http://smart.omicstudio.cloud ), the first database for small molecules with functional implications in plants. The SMART database is devoted to providing and managing small molecules and their associated structural data, chemoinformatic data, protein targets, pathways and induced phenotype/function information. Currently, SMART v1.0 encompasses 1218 unique small molecules which are involved in multiple biological pathways. SMART v1.0 is featured with user-friendly interfaces, through which pathway-centered visualization of small molecules can be efficiently performed, and multiple types of searches (i.e., text search, structure similarity search and sequence similarity search) can be conveniently conducted. SMART v1.0 is also specifically designed to be a small molecule-sharing database, allowing users to release their newly discovered small molecules to public via the Contribute webpage. The SMART database will facilitate the comprehensive understanding of small molecules in complex biological processes in plants.