Areca catechu-(Betel-nut)-induced whole transcriptome changes in a human monocyte cell line that may have relevance to diabetes and obesity; a pilot study

BACKGROUND

Betel-nut consumption is the fourth most common addictive habit globally and there is good evidence linking the habit to obesity, type 2 diabetes (T2D) and the metabolic syndrome. The aim of our pilot study was to identify gene expression relevant to obesity, T2D and the metabolic syndrome using a genome-wide transcriptomic approach in a human monocyte cell line incubated with arecoline and its nitrosated products.

RESULTS

The THP1 monocyte cell line was incubated separately with arecoline and 3-methylnitrosaminopropionaldehyde (MNPA) in triplicate for 24 h and pooled cDNA indexed paired-end libraries were sequenced (Illumina NextSeq 500). After incubation with arecoline and MNPA, 15 and 39 genes respectively had significant changes in their expression (q < 0.05, log fold change 1.5). Eighteen of those genes have reported associations with T2D and obesity in humans; of these genes there was most marked evidence for CLEC10A, MAPK8IP1, NEGR1, NQ01 and INHBE genes.

CONCLUSIONS

Our preliminary studies have identified a large number of genes relevant to obesity, T2D and metabolic syndrome whose expression was changed significantly in human TPH1 cells following incubation with betel-nut derived arecoline or with MNPA. These findings require validation by further cell-based work and investigation amongst betel-chewing communities.

Vildagliptin, a dipeptidyl peptidase-4 inhibitor, reduces betel-nut induced carcinogenesis in female mice

AIM

Betel-nut, a popular masticatory among Southeast Asian populations is a class I carcinogen, previously associated with dyslipidemia and aberrant lipid metabolism, and is reported to be used more frequently by females, than males. This study investigates the potential of repurposing the anti-diabetic drug, vildagliptin, a dipeptidyl peptidase-4 inhibitor, for alleviating the oncogenic condition in female Swiss Albino mice administered an aqueous extract of betel-nut (AEBN) orally (2 mg ml^-1) for 24 weeks.

MAIN METHODS

Tissues were investigated by histopathological, immunohistochemical and apoptosis assays. Biochemical analyses of oxidative stress markers and lipid profile were performed using different tissues and sera. The expressions of different proteins involved in lipid metabolism and oncogenic pathways were evaluated by Western blotting.

KEY FINDINGS

AEBN induced carcinogenesis primarily in the liver by significantly impairing AMPK signaling, inducing oxidative stress, activating Akt/mTOR signaling, increasing Ki-67 immunoreactivity and cyclin D1 expression, and significantly diminishing apoptosis. Co-administration of AEBN with vildagliptin (10 mg kg^-1 body weight) for 8 weeks reduced liver dysplasia, and significantly decreased free palmitic acid, increased free oleic acid, normalized lipid profile, decreased oxidative stress, cyclin D1 expression, Ki-67 immunoreactivity, and Bcl2 expression, and increased the ratio of apoptotic/non-apoptotic cells. Mechanistically, vildagliptin elicited these physiological and molecular alterations by restoring normal AMPK signaling and reducing the cellular expressions of FASN and HMGCR, restoring AMPK-dependent phosphorylation of p53 at Ser-15 and reducing Akt/mTOR signaling.

SIGNIFICANCE

These results indicate that vildagliptin may alleviate betel-nut induced carcinogenesis in the liver of female mice.

Treatment with the anti-diabetic drug metformin ameliorates betel-nut induced carcinogenesis in a murine model

BACKGROUND

Metformin, a widely used anti-diabetic drug has gained enormous attention as an anticancer agent. This study seeks to investigate the efficacy of metformin in ameliorating aqueous extract of betel-nut (AEBN) and arecoline induced carcinogenesis in a murine model.

METHODS

Swiss albino mice were exposed to AEBN (2 mg ml-1) and arecoline (10 μg ml-1) in drinking water for 16 weeks followed by co-administration of metformin (75 mg kg-1 or 150 mg kg-1) for 4 or 8 weeks. Histological changes and oxidative stress were assessed by haematoxylin and eosin staining, TBARS assay and protein carbonylation assay respectively. Lipid profile was determined using an automated analyzer. Expression of total and phosphorylated AMPK, ACC and p53 were determined by immunoblotting.

RESULTS

AEBN and arecoline induced dyslipidemia by downregulating AMPK (Thr-172) and activating ACC (Ser-79); they also downregulated tumor suppressor p53 (Ser-15). Metformin treatment induced AMPK-dependent alleviation of dyslipidemia in a dose and time dependent manner, upregulated p53 (Ser-15), restored tissue architecture and reduced oxidative stress in tissues of AEBN and arecoline treated mice.

CONCLUSION

This study establishes that betel nut induces dyslipidemia through its alkaloid, arecoline by inhibition of AMPK (Thr-172) and activation of ACC (Ser-79) and highlights the therapeutic potential of metformin for treatment of betel-nut induced carcinogenesis, indicating the repurposing of the old drug in a new avenue.