Chemopreventive effect of epigallocatechin-3-gallate (EGCG) and folic acid on the N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastrointestinal cancer in rat model

RNA-Seq Analysis Reveals Dendrobium officinale Polysaccharides Inhibit Precancerous Lesions of Gastric Cancer through PER3 and AQP4

Purpose

There has been mounting evidence that Dendrobium officinale polysaccharides (DOP), a traditional Chinese medicine, are a potential candidate treatment for N-methyl-N'-nitro-N-nitrosoguanidine- (MNNG-) induced precancerous lesions of gastric cancer (PLGC). However, the underlying mechanisms have not been adequately addressed.

Method

We utilized RNA-Seq analysis to investigate possible molecular targets and then used Venn software to identify the differentially expressed genes (DEGs). Further, we analyzed these DEGs with core analysis, upstream analysis, and interaction network analysis by IPA software and validated the DEGs by real-time PCR and Western blot.

Result

78 DEGs were identified from the normal control group (CON), the PLGC model group (MOD), and the DOP-treated group (DOP) by the Venn software. Further analysis of these DEGs, including core analysis, upstream analysis, and interaction network analysis, was performed by Ingenuity Pathway Analysis (IPA). The main canonical pathways involved were SPINK1 Pancreatic Cancer Pathway (-log (P value) = 4.45, ratio = 0.0667) and Circadian Rhythm Signaling (-log (P value) = 2.33, ratio = 0.0606). Circadian Rhythm Signaling was strongly upregulated in the model group versus the DOP group. CLOCK was predicted to be strongly activated (z-score = 2.236) in upstream analysis and induced the downstream PER3. In addition, the relative mRNA expression levels of seven DEGs (CD2AP, ECM1, AQP4, PER3, CMTM4, ESRRG, and KCNJ15) from RT-PCR agreed with RNA-Seq data from MOD versus CON and MOD versus DOP groups. The gene and protein expression levels of PER3 and AQP4 were significantly downregulated in the PLGC model and significantly increased by DOP treatment (9.6 g/kg).

Conclusions

These findings not only showed DOP inhibits PLGC development by upregulating the PER3 and AQP4 gene and protein expression but also suggested that its mechanism of action involved modulating the Circadian Rhythm Signaling pathway.

Epigallocatechin gallate induces chemopreventive effects on rats with diethylnitrosamine‑induced liver cancer via inhibition of cell division cycle 25A

Epigallocatechin gallate (EGCG), the most active monomer in green tea (GT), has demonstrated potential therapeutic and preventive effects on various tumors, including liver cancer. However, the anticancer mechanisms of EGCG in liver cancer remain to be elucidated. The abnormal expression of cell division cycle 25A (CDC25A) has been identified in liver cancer and is closely associated with malignancy and poor prognosis in patients with hepatocellular carcinoma (HCC). The present study used human hepatoma cell lines and rats with diethylnitrosamine (DEN)-induced HCC as models to investigate the association between the effect of EGCG on liver cancer and regulation of the p21waf1/Cip1/CDC25A axis. The results demonstrated that EGCG can inhibit the proliferation of HepG2 and Huh7 cells, reduce the expression of CDC25A and increase the expression of p21waf1/Cip1 in HepG2. In vivo, HCC was induced by DEN in Sprague-Dawley rats. EGCG significantly reduced tumor volume and improved the survival rates of rats with HCC. The expression levels of CDC25A mRNA and protein in liver tissues and the level of serum γ glutamyl transpeptidase in rats treated with EGCG were significantly decreased, while p21waf1/Cip1 mRNA and protein expression levels were increased compared with the HCC group, in the process of DEN-induced HCC. No significant difference in the chemopreventive effects on liver cancer was observed between GT extract and EGCG under an EGCG equivalence condition. Thus, EGCG can suppress human hepatoma cell proliferation and prolong the survival of rats with HCC, and the potential mechanism may be involved in EGCG-induced upregulation of p21waf1/Cip1 and downregulation of CDC25A.

Antimutagenic activity of vitamin B1 against damages induced by chemical and physical mutagens in Salmonella typhimurium and Escherichia coli

Thiamine (vitamin B1) is an essential nutrient acting mainly as an enzymatic cofactor on diverse cell processes. It has been reported that vitamin B1 has a significant role in the signaling pathways related to the response to adverse environmental conditions (chemical and physical). The objectives of this study were to evaluate the antimutagenic potential of vitamin B1 in front of DNA-alkylating agents in the presence/absence of ogt and ada repairing genes in Salmonella typhimurium strains and against damage induced by ultraviolet light type C in Escherichia coli strains mutated at the uvrABC system and recBCD enzymes. For S. typhimurium, an antimutagenesis test (Ames test) was performed using strains deficient in one or both genes (YG7100 ada^-/ogt⁺, YG7104 ada⁺/ogt^-, YG7108 ada^-/ogt^-). For E. coli, mutated strains (K-12 derived strains Hfr H180 uvrB⁺/recA⁺, W3110 uvrB⁺/recA^- and ATCC®8739 uvrB^-/recA⁺) were exposed to UV-C light at different time intervals, with and without vitamin B1. Our results showed that thiamine is an antimutagen against methyl-N-nitro-N-nitrosoguanidine or ethyl-N-nitro-N-nitrosoguanidine only when the ogt gene is present. While for E. coli, the presence of vitamin B1 increased the survival rate, implying an antimutagenesis independent of uvrABC repairing system and recBCD enzymes.

Preventive effect of Actinidia valvata Dunn extract on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastrointestinal cancer in rats

PURPOSE

This study was conducted to assess the preventive effect of Actinidia valvata Dunn (AVD) extract on an animal model of gastrointestinal carcinogenesis on the basis of changes in tumor incidence, cell proliferation, and apoptosis.

MATERIALS AND METHODS

Seventy-five male Wistar rats were divided into five different treatment groups with 15 rats in each group. Group I was given normal feed, whereas Groups II to IV were treated with 10% sodium chloride in the first six weeks and 100 ug/mL of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 24 weeks. Group II was then given normal feed, whereas Group III was given AVD extract (0.24 g/kg/day) for 12 weeks. Group IV was given AVD extract from the first week to the 36th week, whereas Group V was treated with AVD extract alone for 36 weeks. All rats were sacrificed at the end of the 36-week experiment and assessed for the presence of gastrointestinal tumors. The occurrence of cancer was evaluated by histology. Bax, Bcl-2, Caspase-3, and cyclinD1 were determined by immunohistochemical staining and Western blotting.

RESULTS

The incidences of gastric cancer were 0% in Group I, 73.3% in Group II, 33.3% in Group III, 26.7% in Group IV, and 0% in Group V. Bcl-2 and cyclinD1 expression was decreased in AVD extract treated groups, whereas Bax and Caspase-3 expression was increased. Comparison with group II revealed significant differences (p<0.01).

CONCLUSIONS

AVD extract exhibits an obvious preventive effect on gastrointestinal carcinogenesis induced by MNNG in rats through the regulation of cell proliferation and apoptosis.

Effect of Dendrobium officinale Extraction on Gastric Carcinogenesis in Rats

Dendrobium officinale (Tie Pi Shi Hu in Chinese) has been widely used to treat different diseases in China. Anticancer effect is one of the important effects of Dendrobium officinale. However, the molecular mechanism of its anticancer effect remains unclear. In the present study, gastric carcinogenesis in rats was used to evaluate the effect of Dendrobium officinale on cancer, and its pharmacological mechanism was explored. Dendrobium officinale extracts (4.8 and 2.4 g/kg) were orally administered to the rats of the gastric carcinogenesis model. Compared with the cancer model group, the high dose of Dendrobium officinale extracts significantly inhibited the rate of carcinogenesis. Further analysis revealed that Dendrobium officinale extracts could regulate the DNA damage, oxidative stress, and cytokines related with carcinogenesis and induce cell apoptosis in order to prevent gastric cancer.

A genome-wide study of DNA methylation modified by epigallocatechin-3-gallate in the CAL-27 cell line

In order to gain greater understanding of the mechanisms underlying the effect of epigallocatechin-3-gallate (EGCG) on DNA methylation and its chemopreventative action in oral squamous cell carcinoma (OSCC), a genome‑wide methylation and mRNA expression screen was performed in the CAL‑27 cell line with and without EGCG (100 µM) treatment. A total of 761 differentially methylated gene loci were identified following treatment with EGCG. Comparison of gene expression profiling in OSCC samples revealed 184 transcripts with a significant difference (P<0.05) and a fold change difference >2 compared with controls. Gene ontology analysis of differentially methylated loci and functional annotation of the differentially expressed genes indicated that the main pathways involved were metabolic, mitogen‑activated protein kinase (MAPK), wnt, and cell cycle pathways. In conclusion, the present study indicates that EGCG can affect the methylation status and gene expression in the CAL‑27 cell line. Additionally, the changes in several important signaling pathways may reveal the antitumor mechanism of EGCG.

Carcinoma of the stomach: A review of epidemiology, pathogenesis, molecular genetics and chemoprevention

Carcinoma of the stomach is still the second most common cause of cancer death worldwide, although the incidence and mortality have fallen dramatically over the last 50 years in many regions. The incidence of gastric cancer varies in different parts of the world and among various ethnic groups. Despite advances in diagnosis and treatment, the 5-year survival rate of stomach cancer is only 20 per cent. Stomach cancer can be classified into intestinal and diffuse types based on epidemiological and clinicopathological features. The etiology of gastric cancer is multifactorial and includes both dietary and nondietary factors. The major diet-related risk factors implicated in stomach cancer development include high content of nitrates and high salt intake. Accumulating evidence has implicated the role of Helicobacter pylori (H. pylori) infection in the pathogenesis of gastric cancer. The development of gastric cancer is a complex, multistep process involving multiple genetic and epigenetic alterations of oncogenes, tumor suppressor genes, DNA repair genes, cell cycle regulators, and signaling molecules. A plausible program for gastric cancer prevention involves intake of a balanced diet containing fruits and vegetables, improved sanitation and hygiene, screening and treatment of H. pylori infection, and follow-up of precancerous lesions. The fact that diet plays an important role in the etiology of gastric cancer offers scope for nutritional chemoprevention. Animal models have been extensively used to analyze the stepwise evolution of gastric carcinogenesis and to test dietary chemopreventive agents. Development of multitargeted preventive and therapeutic strategies for gastric cancer is a major challenge for the future.