ObjectiveRandomized controlled trials and observational studies have yielded inconsistent results on the effects of metformin on vitamin B12 reduction. We therefore performed a systematic review to analyze the effects of metformin on vitamin B12 concentration.MethodsPubMed, Medline, Embase, and the Cochrane central registry of controlled trials were searched to identify randomized controlled trials and observational studies exploring the association between metformin and vitamin B12 concentration in patients with type 2 diabetes mellitus or polycystic ovary syndrome. The main outcome measure was changes in serum vitamin B12 concentration after 6–208 weeks of treatment with metformin, as compared with placebo or other anti-hyperglycemic therapy.ResultsSix randomized controlled trials met the inclusion criteria. Serum vitamin B12 concentrations were significantly lower in patients treated with metformin than in those who received placebo or rosiglitazone (mean difference [MD], −53.93 pmol/L; 95% confidence interval [CI], −81.44 to −26.42 pmol/L, P = 0.0001). Subgroup analysis identified four trials in which patients received a lower dose of metformin (<2000 mg/d) and two in which they received a higher dose (≥2000 mg/d), with MDs in vitamin B12 concentration after metformin treatment of −37.99 pmol/L (95% CI, −57.44 to −18.54 pmol/L, P = 0.0001) and −78.62 pmol/L (95% CI, −106.37 to −50.86 pmol/L, P<0.00001), respectively.ConclusionsThe reduction of vitamin B12 may be induced by metformin in a dose dependent manner.

Globally, epithelial ovarian cancer (EOC) is the most common gynecological malignancy with poor prognosis. The expression and oncogenic roles of ubiquitin specific peptidase 5 (USP5) have been reported in several cancers except EOC. In the current study, USP5 amplification was highly prevalent in patients with EOC and associated with higher mRNA expression of USP5. USP5 amplification and overexpression was positively correlated with poor prognosis of patients of ovarian serous carcinomas. Disruption of USP5 profoundly repressed cell proliferation by inducing cell cycle G0/G1 phase arrest in ovarian cancer cells. Additionally, USP5 knockdown inhibited xenograft growth in nude mice. Knockdown of USP5 decreased histone deacetylase 2 (HDAC2) expression and increased p27 (an important cell cycle inhibitor) expression in vitro and in vivo. The promoting effects of USP5 overexpression on cell proliferation and cell cycle transition, as well as the inhibitory effects of USP5 overexpression on p27 expression were mediated by HDAC2. Moreover, USP5 interacted with HDAC2, and disruption of USP5 enhanced the ubiquitination of HDAC2. HDAC2 protein was positively correlated USP5 protein, and negatively correlated with p27 protein in ovarian serous carcinomas tissues. Collectively, our data suggest the oncogenic function of USP5 and the potential regulatory mechanisms in ovarian carcinogenesis.

Bladder cancer (BC) is among the most common tumors with a high recurrence rate, necessitating noninvasive and sensitive diagnostic methods. Accurate detection of exfoliated tumor cells (ETCs) in urine is crucial for noninvasive BC diagnosis but suffers from limited sensitivity when ETCs are rare and confounded by reactive, regenerative, or reparative cells. Singlecell sequencing (SCS) enables accurate detection of ETCs by surveying oncogenic driver mutations or genome-wide copy number alternations. To overcome the low-throughput limitation of SCS, we report a SCS-validated cellular marker, hexokinase 2 (HK2), for high-throughput screening cells in urine and detecting ETCs engaging elevated glycolysis. In the SCS-based training set, a total of 385 cells from urine samples of eight urothelial carcinoma (UC) patients were sequenced to establish a HK2 threshold that achieved >90% specificity for ETC detection. This urine-based HK2 assay was tested with a blinded patient group (n = 384) including UC and benign genitourinary disorders as a validation cohort for prospectively evaluating diagnostic accuracy. The sensitivity, specificity, positive predictive value, and negative predictive value of the assay were 90, 88, 83, and 93%, respectively, which were superior to urinary cytology. For investigating the potential to be a screening test, the HK2 assay was tested with a group of healthy individuals (n = 846) and a 6-month follow-up. The specificity was 98.4% in this health group. Three participants were found to have >5 putative ETCs that were sequenced to exhibit recurrent copy number alternations characteristic of malignant cells, demonstrating early BC detection before current clinical methods.