Dietary riboflavin deficiency induces ariboflavinosis and esophageal epithelial atrophy in association with modification of gut microbiota in rats.

PURPOSE: Riboflavin deficiency causes ariboflavinosis, a common nutritional deficiency disease. The purpose of this study is to investigate the effects of riboflavin deficiency on the important internal organs and its potential mechanisms. METHODS: Experiment 1, male F344 rats were randomly assigned to R6 (normal riboflavin, 6 mg/kg) and R0 (riboflavin-deficient, 0 mg/kg) groups. Experiment 2 rats were assigned to R6, R0.6 (0.6 mg/kg) and R0.06 (0.06 mg/kg) groups. Experiment 3 rats were assigned to R6 and R0 → R6 (riboflavin replenishment) groups. Bacterial communities were analyzed based on 16S rRNA gene sequencing. RESULTS: Riboflavin deficiency induced ariboflavinosis (R0.06 46.7%; R0 72%) and esophageal epithelial atrophy (R0.06 40%; R0 44%) in rats, while the R6 group did not display symptoms (P < 0.001, respectively). Esophageal epithelial atrophy occurred simultaneously (R0.06 66.7%; R0 63.6%) with ariboflavinosis or appeared alone (R0.06 33.3%; R0 36.4%). Esophagus is the most vulnerable internal organ. Riboflavin deficiency followed by replenishment (R0 → R6) was effective in treating ariboflavinosis (83.3% vs. 0%, P < 0.001) and esophageal epithelial atrophy (66.7% vs. 20%, P = 0.17). Riboflavin deficiency modulated gut microbiota composition. The several key genera (Romboutsia, Turicibacter and Clostridium sensu stricto 1) were strongly correlated with ariboflavinosis and esophageal epithelial atrophy (P < 0.01 or P < 0.05). The potential mechanism is that gut microbiota affects body's xenobiotic biodegradation and metabolism, and genomic instability. CONCLUSIONS: Riboflavin deficiency induces ariboflavinosis and esophageal epithelial atrophy by modulating the gut microbiota, and offers new Queryinsight into riboflavin deficiency and esophageal lesions.

SSAO inhibitors suppress hepatocellular tumor growth in mice.

Vascular adhesion protein-1 (VAP-1) is both an endothelial adhesion molecule involved in leukocytes emigration, and an oxidase belonging to the family of semicarbazide-sensitive amine oxidases (SSAOs). The enzyme activity of VAP-1 plays an important role in the migration of myeloid-derived suppressor cells (MDSCs) into tumor site, and SSAO inhibitors can block the function of VAP-1. The effects of SSAO inhibitors on leukocyte infiltration and tumor progression were evaluated in H22 hepatocellular carcinoma-bearing C57BL/6 mice. Tumor weight and volume were measured after SSAO inhibitor treatment. Then, MDSCs recruitment and neo-angiogenesis were determined using immunostaining. SSAO inhibitors significantly blocked the catalytic activity of VAP-1 in tumor, attenuated tumor progression, and reduced neo-angiogenesis. CD11b(+) and Gr-1(+) MDSCs, which normally infiltrate into tumors, were significantly diminished in tumor-bearing mice treated with SSAO inhibitors. The present study demonstrated that SSAO inhibitors might have an anti-tumor effect on hepatocellular carcinoma by inhibiting recruitment of CD11b(+) and Gr-1(+) cells and hindering angiogenesis, which could be attributed to impairing the catalytic activity of VAP-1.

[Determination of serum copper and zinc in different chemical forms by graphite furnace atomic absorption spectrometry with ethanol-EDTA precipitation method].

A simple and reliable method was developed for the determination of serum copper and zinc in different chemical forms by graphite furnace atomic absorption spectrometry (GFAAS) with ethanol-EDTA precipitation. The serum and ethanol were mixed with volume ratio 1 : 2. The mixture was incubated at 70 degrees C and ultra-centrifuged to precipitate proteins. Zinc and copper can be released from albumin after EDTA treating. Thus, macroglobulin-zinc, ceruloplasmin-copper, and albumin-bound zinc or copper could be determined by two proposed precipitation steps. The determination limit of copper (3sigma) was 1.2 microg x L(-1) and the recovery was 92.3%-104%, while the determination limit of zinc (3sigma) was 0.098 microg x L(-1), and the recovery was 90%-107%. This two-step precipitation method can be used to determine serum zinc and copper in various chemical forms in tumor, Wilson patients and heathy human.

Dietary riboflavin deficiency induces genomic instability of esophageal squamous cells that is associated with gut microbiota dysbiosis in rats.

SCOPE: Epidemiologic evidence suggests that riboflavin (RBF) deficiency is a specific nutritional predisposition for esophageal cancer. The aim of this study is to investigate the potential roles of gut microbiota in esophageal tumorigenesis caused by the RBF deficiency. METHODS: Male F344 rats were subcutaneously injected with the chemical carcinogen N-nitrosomethylbenzylamine (NMBA, 0.35 mg kg-1). Rats were assigned to 4 groups, denoted as R6 (normal RBF, 6 mg kg-1), R6N (normal RBF combined with NMBA), R6N → R0N (normal RBF conversion to RBF-deficiency), and R0N → R6N (RBF-deficiency conversion to normal RBF). Bacterial communities were analyzed based on high-throughput 16S rRNA gene sequencing. Oxidative DNA damage and double-strand break markers were studied by immunohistochemistry. RESULTS: The R6N → R0N diet enhanced the incidence of esophageal intraepithelial neoplasia (EIN, 40 weeks 66.7% vs. 25 weeks 16.7%, P < 0.05). RBF deficiency and replenishment modulated the gut microbiota composition. The gut microbiota (e.g. Caulobacteraceae, Sphingomonas and Bradyrhizobium) affected xenobiotic biodegradation and the genomic instability of the host. Furthermore, the RBF deficiency aggravated oxidative DNA damage and DNA double-strand breaks (immunohistochemistry) in the esophageal epithelium, whereas the RBF replenishment had the opposite effect (P < 0.05, respectively). CONCLUSIONS: RBF deficiency promotes NMBA-induced esophageal tumorigenesis, which is associated with gut microbiota-associated genomic instability, and offers new insights into the role of RBF deficiency in esophageal carcinogenesis.

Correction: Dietary riboflavin deficiency induces genomic instability of esophageal squamous cells that is associated with gut microbiota dysbiosis in rats.

Correction for 'Dietary riboflavin deficiency induces genomic instability of esophageal squamous cells that is associated with gut microbiota dysbiosis in rats' by Feng Pan et al., Food Funct., 2020, DOI: .

Decreased plasma riboflavin is associated with poor prognosis, invasion, and metastasis in esophageal squamous cell carcinoma.

BACKGROUND: Riboflavin deficiency confers a predisposition for esophageal cancer. The role of plasma riboflavin levels in development and prognosis of individuals with digestive tract inflammation and ulcer (DTIU), digestive tract polyps (DTPs), and ESCC is not well understood. METHODS: We performed a cross-sectional study, including 177 DTIU, 80 DTP, and 324 ESCC cases, to measure the plasma riboflavin levels among the three populations. Correlation between plasma riboflavin levels (categorized as ≥31.8, 6.5-31.8 and ≤6.5 nmol/L groups) and clinical characteristics, as well as survival of ESCC patients (556 cases) was analyzed. RESULTS: There was no difference in plasma riboflavin levels between DTIU, DTP, and ESCC cases (P > 0.05). Plasma riboflavin levels were inversely correlated with invasive depth (correlation coefficient = -0.09, P = 0.026) and lymph node metastasis (correlation coefficient = -0.11, P = 0.010) of ESCC, and ESCC patients with low riboflavin levels had poor recurrence-free survival (P = 0.035) and overall survival (P = 0.003). Decreased riboflavin was a prognostic factor for poor overall survival (HR = 1.91, 95% CI = 1.19-3.07, P = 0.007). CONCLUSIONS: Plasma riboflavin levels in DTIU, DTP, and ESCC patients are similar. Plasma riboflavin levels are associated with the development and prognosis of ESCC.

[Determination of trace free copper and zinc in serum samples by graphite furnace atomic absorption spectrometry after two-step precipitation of protein].

A method was developed for the determination of trace free copper and zinc in serum sample by GFAAS after two-step precipitation. The serum and ethanol were mixed with volume ratio of 1 : 2. The mixture was subsequently denatured at 70 degrees C and centrifuged to precipitate proteins. The determination, limit of copper (3sigma) was 1.2 microg x L(-1) and the recovery was 92.3% - 104%, and the determination. Limit of zinc(3sigma) was 0.098 microg x L(-1) and the recovery was 90%-107%. This two-step precipitation method can be used to determine non-protein-bound copper in tumor patients and healthy people.

Dietary riboflavin deficiency promotes N-nitrosomethylbenzylamine-induced esophageal tumorigenesis in rats by inducing chronic inflammation.

Epidemiological studies in high-incidence areas of esophageal cancer in China suggest that environmental carcinogen N-nitrosomethylbenzylamine (NMBA) and riboflavin (RBF) deficiency may be the main risk factors for esophageal cancer. However, it is not clear that the combination induces cancer. Here, experiment (Exp) 1 evaluated the effects of NMBA and RBF deficiency individually or in combination on esophageal tumorigenesis. Male F344 rats were randomly assigned to 4 groups into a 2 (no NMBA vs. NMBA) × 2 (normal RBF vs. RBF-deficient) factorial design, including normal RBF (6 mg/kg, R6), RBF-deficient (0 mg/kg, R0), normal RBF combined with NMBA (R6N), and RBF-deficient combined with NMBA (R0N) groups. The Exp 2 explored the effects of RBF deficiency at different doses combined with NMBA (0.6 mg/kg, R0.6N; 0.06 mg/kg, R0.06N) on esophageal tumorigenesis. Results showed that R0N enhanced the incidence of esophageal intraepithelial neoplasia (EIN, 53.3%, P = 0.06), including carcinoma in situ, whereas R6N mainly induced the occurrence of esophageal benign hyperplasia (38.9%) and EIN (16.7%). RBF deficiency promotes EIN in a dose-dependent manner, and R0.06N significantly increases the incidence of EIN (57.9%, P < 0.05). Gene expression profiling demonstrated that inflammatory cytokines were highly expressed in R0N EIN tissues, whereas R6N EIN tissues had a proliferation and differentiation gene signature (fold-change > 1.5). Furthermore, RBF deficiency aggravated oxidative DNA damage (8-OHdG) and double-strand breaks (γH2AX) (P < 0.05). Our results suggest that RBF deficiency causes chronic inflammation-associated genomic instability contributes to NMBA-induced esophageal tumorigenesis.

Lysine-specific demethylase 1 in breast cancer cells contributes to the production of endogenous formaldehyde in the metastatic bone cancer pain model of rats.

BACKGROUND: Bone cancer pain seriously affects the quality of life of cancer patients. Our previous study found that endogenous formaldehyde was produced by cancer cells metastasized into bone marrows and played an important role in bone cancer pain. However, the mechanism of production of this endogenous formaldehyde by metastatic cancer cells was unknown in bone cancer pain rats. Lysine-specific demethylase 1 (LSD1) is one of the major enzymes catalyzing the production of formaldehyde. The expression of LSD1 and the concentration of formaldehyde were up-regulated in many high-risk tumors. OBJECTIVE: This study aimed to investigate whether LSD1 in metastasized MRMT-1 breast cancer cells in bone marrows participated in the production of endogenous formaldehyde in bone cancer pain rats. METHODOLOGY/PRINCIPAL FINDINGS: Concentration of the endogenous formaldehyde was measured by high performance liquid chromatography (HPLC). Endogenous formaldehyde dramatically increased in cultured MRMT-1 breast cancer cells in vitro, in bone marrows and sera of bone cancer pain rats, in tumor tissues and sera of MRMT-1 subcutaneous vaccination model rats in vivo. Formaldehyde at a concentration as low as the above measured (3 mM) induced pain behaviors in normal rats. The expression of LSD1 which mainly located in nuclei of cancer cells significantly increased in bone marrows of bone cancer pain rats from 14 d to 21 d after inoculation. Furthermore, inhibition of LSD1 decreased the production of formaldehyde in MRMT-1 cells in vitro. Intraperitoneal injection of LSD1 inhibitor pargyline from 3 d to 14 d after inoculation of MRMT-1 cancer cells reduced bone cancer pain behaviors. CONCLUSION: Our data in the present study, combing our previous report, suggested that in the endogenous formaldehyde-induced pain in bone cancer pain rats, LSD1 in metastasized cancer cells contributed to the production of the endogenous formaldehyde.