Polymorphisms in miRNA binding sites involved in metabolic diseases in mice and humans

Childhood obesity, metabolic syndrome, and oxidative stress: microRNAs go on stage

The incidence of childhood obesity and metabolic syndrome has grown notably in the last years, becoming major public health burdens in developed countries. Nowadays, oxidative stress is well-recognized to be closely associated with the onset and progression of several obesity-related complications within the framework of a complex crosstalk involving other intertwined pathogenic events, such as inflammation, insulin disturbances, and dyslipidemia. Thus, understanding the molecular basis behind these oxidative dysregulations could provide new approaches for the diagnosis, prevention, and treatment of childhood obesity and associated disorders. In this respect, the transcriptomic characterization of miRNAs bares great potential because of their involvement in post-transcriptional modulation of genetic expression. Herein, we provide a comprehensive literature revision gathering state-of-the-art research into the association between childhood obesity, metabolic syndrome, and miRNAs. We put special emphasis on the potential role of miRNAs in modulating obesity-related pathogenic events, with particular focus on oxidative stress.

Identification of MicroRNAs Associated with Prediabetic Status in Obese Women

MicroRNAs (miRNAs) recently emerged as means of communication between insulin-sensitive tissues to mediate diabetes development and progression, and as such they present a valuable proxy for epigenetic alterations associated with type 2 diabetes. In order to identify miRNA markers for the precursor of diabetes called prediabetes, we applied a translational approach encompassing analysis of human plasma samples, mouse tissues and an in vitro validation system. MiR-652-3p, miR-877-5p, miR-93-5p, miR-130a-3p, miR-152-3p and let-7i-5p were increased in plasma of women with impaired fasting glucose levels (IFG) compared to those with normal fasting glucose and normal glucose tolerance (NGT). Among these, let-7i-5p and miR-93-5p correlated with fasting blood glucose levels. Human data were then compared to miRNome data obtained from islets of Langerhans and adipose tissue of 10-week-old female New Zealand Obese mice, which differ in their degree of hyperglycemia and liver fat content. Similar to human plasma, let-7i-5p was increased in adipose tissue and islets of Langerhans of diabetes-prone mice. As predicted by the in silico analysis, overexpression of let-7i-5p in the rat β-cell line INS-1 832/12 resulted in downregulation of insulin signaling pathway components (Insr, Rictor, Prkcb, Clock, Sos1 and Kcnma1). Taken together, our integrated approach highlighted let-7i-5p as a potential regulator of whole-body insulin sensitivity and a novel marker of prediabetes in women.

Hypoxia-induced PPFIA4 accelerates the progression of ovarian cancer through glucose metabolic reprogramming

Dysregulated glycolysis promotes growth and metastasis, which is one of the metabolic characteristics of ovarian cancer. Based on bioinformatics analysis, liprin-alpha-4 (PPFIA4) is a gene associated with hypoxia, and we aimed to investigate the potential mechanism of PPFIA4 during the reprogramming of glucose metabolism in ovarian cancer cells. Currently, the cell viability of ovarian cancer cells under the hypoxia treatment was evaluated by CCK-8 assay, and cell migration and invasion were measured by transwell assay and western blot. The effects of hypoxia treatment on glucose uptake, lactate production, extracellular acidification rate (ECAR), adenosine triphosphate (ATP), reactive oxygen species (ROS), Nicotinamide adenine dinucleotide phosphate (NADPH) and its oxidized form NADP + , and oxygen consumption rate (OCR) in ovarian cancer cells were examined. Then PPFIA4 was identified through bioinformatic analysis, and the regulatory effects of PPFIA4 on glucose metabolic reprogramming. Our data suggested that hypoxia enhanced the migration and invasion ability of ovarian cancer cells in vitro, and promoted the glucose metabolic reprogramming of ovarian cancer cells. Ovarian cancer cell viability, migration, and invasion were inhibited after PPFIA4 knockdown. Inhibition of PPFIA4 inhibited hypoxic-induced glucose metabolic reprogramming in ovarian cancer cells. In addition, PPFIA4 was found to bind to hypoxia-inducible factor 1alpha (HIF1A), and HIF1A prominently induced PPFIA4 expression. Collectively, HIF1A mediated upregulation of PPFIA4 and promoted reprogramming of glucose metabolism in ovarian cancer cells. Therefore, PPFIA4 may be a therapeutic target for ovarian cancer intervention.

PPFIA4 promotes castration-resistant prostate cancer by enhancing mitochondrial metabolism through MTHFD2

Background

The development of castration-resistant prostate cancer (CRPC) remains a major obstacle in the treatment of prostate cancer (PCa). Dysregulated mitochondrial function has been linked to the initiation and progression of diverse human cancers. Deciphering the novel molecular mechanisms underlying mitochondrial function may provide important insights for developing novel therapeutics for CRPC.

Methods

We investigate the expression of the protein tyrosine phosphatase receptor type F polypeptide interacting protein alpha 4 (PPFIA4) using public datasets and tumor specimens from PCa cases by immunohistochemistry. Gain- and loss-of-function studies are performed in PCa cell lines and mouse models of subcutaneous xenograft to characterize the role of PPFIA4 in CRPC. Gene expression regulation is evaluated by a series of molecular and biochemical experiments in PCa cell lines. The therapeutic effects of methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) inhibitor combined enzalutamide are assessed using in vitro functional assays and in vivo mouse models.

Results

We show that the increase of PPFIA4 exacerbates aggressive phenotype resembling CRPC. A fraction of PPFIA4 localizes to mitochondria and interacts with MTHFD2, a key enzyme for one-carbon metabolism. Androgen deprivation increases the translocation of PPFIA4 into mitochondria and increases the interaction between PPFIA4 and MTHFD2, which result in the elevation of tyrosine phosphorylated MTHFD2. Consequently, the levels of NADPH synthesis increase, resulting in protection against androgen deprivation-induced mitochondrial dysfunction, as well as promotion of tumor growth. Clinically, PPFIA4 expression is significantly increased in CRPC tissues compared with localized PCa ones. Importantly, an MTHFD2 inhibitor, DS18561882, combined with enzalutamide can significantly inhibit CRPC cell proliferation in vitro and tumor growth in vivo.

Conclusion

Overall, our findings reveal a PPFIA4-MTHFD2 complex in mitochondria that links androgen deprivation to mitochondrial metabolism and mitochondrial dysfunction, which suggest a potential strategy to inhibit CRPC progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02331-3.

TOX4, an insulin receptor-independent regulator of hepatic glucose production, is activated in diabetic liver

Increased hepatic glucose production (HGP) contributes to hyperglycemia in type 2 diabetes. Hormonal regulation of this process is primarily, but not exclusively, mediated by the AKT-FoxO1 pathway. Here, we show that cAMP and dexamethasone regulate the high-mobility group superfamily member TOX4 to mediate HGP, independent of the insulin receptor/FoxO1 pathway. TOX4 inhibition decreases glucose production in primary hepatocytes and liver and increases glucose tolerance. Combined genetic ablation of TOX4 and FoxO1 in liver has additive effects on glucose tolerance and gluconeogenesis. Moreover, TOX4 ablation fails to reverse the metabolic derangement brought by insulin receptor knockout. TOX4 expression is increased in livers of patients with steatosis and diabetes and in diet-induced obese and db/db mice. In the latter two murine models, knockdown Tox4 decreases glycemia and improves glucose tolerance. We conclude that TOX4 is an insulin receptor-independent regulator of HGP and a candidate contributor to the pathophysiology of diabetes.

Regulation of KRAS protein expression by miR-544a and KRAS-LCS6 polymorphism in wild-type KRAS sporadic colon adenocarcinoma

Colorectal carcinoma (CRC) results from the accumulation of genetic mutations and alterations in signaling pathways. KRAS is mutated in 40% of CRC cases and is involved in increased tumor cells proliferation and survival. Although KRAS mutations are a dominant event in CRC tumorigenesis, increased wild-type KRAS expression has a similar effect on accelerated tumor growth. In this study, we investigated the KRAS status in correlation with clinicopathological features in sporadic CRC and more importantly the role of let-7a-5p and miR-544a-3p in the regulation of wild-type KRAS protein expression in the tumor center (T1) and invasive tumor front (T2). Analysis showed that 39.1% of tumor samples had KRAS mutations. In wild-type KRAS tumors, 62.0% were positive for KRAS protein expression and there was a higher percentage of KRAS-positive tumor cells and a higher intensity of immunohistochemical reaction in T2 than in T1 samples. This could not be attributed to differences in KRAS mRNA levels, suggesting regulation via miR-544a-3p expression which was significantly decreased in T2 samples. Furthermore, we demonstrated that tumor samples carrying the KRAS-LCS6 variant allele had significantly higher protein expression of the wild-type KRAS. Our results suggest the role of the KRAS-LCS6 polymorphism and miR-544a-3p expression in the regulation of wild-type KRAS protein expression in sporadic CRC.

PPFIA4 Promotes Colon Cancer Cell Proliferation and Migration by Enhancing Tumor Glycolysis

Dysregulated glycolysis is one of the mechanisms employed by cancer cells to facilitate growth and metastasis. Here we aimed to characterize the PPFIA4 gene, as a glycolysis-related oncogene in promoting the proliferation and migration of colon cancer cells. Using bioinformatical tools including The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis (GEPIA), we found that PPFIA4 expression and methylation levels were higher in colon cancer tissues of different stages than in normal tissues. Higher PPFIA4 level was also positively correlated with poorer survival of patients. PPFIA4 upregulation also correlated with poor prognosis and higher clinical stages of colon cancer patients. Colon cancer cell viability, migration and migration were enhanced after PPFIA4 overexpression. EMT markers and glycolysis were upregulated after PPFIA4 overexpression. PPFIA4 expression was found to be positively correlated with PFKFB3 and ENO2 levels, while knockdown of PFKFB3 and ENO2 reduced cell proliferation, migration, invasion and glycolysis. PPFIA4 upregulation is a potential biomarker in colon cancer which promotes proliferation, migration, invasion and glycolysis. The upregulation of PFKFB3/ENO2 signaling by PPFIA4 is a potential mechanism underlying the oncogenic effects of PPFIA4.

Involvement of miR-142 and miR-155 in Non-Infectious Complications of CVID

BACKGROUND AND OBJECTIVES

Common variable immunodeficiency (CVID) is the most prevalent antibody impairment. It is characterized by failure in immunoglobulin and protective antibody generation and defined by an increased tendency toward bacterial infections, autoimmunity, and malignancy. Most CVID diagnoses do not follow a classical Mendelian pattern of inheritance. In recent years, CVID has been considered an epigenetic phenomenon in the majority of cases, overtaking previous monogenetic and/or polygenetic theories. The aim of this study was to review the role of microRNAs (miRNAs) in CVID, focusing on the involvement of the same miRNAs in various non-infectious clinical complications of CVID, mainly autoimmunity and/or cancer.

MATERIALS AND METHODS

A bibliographic search of the scientific literature was carried out independently by two researchers in scientific databases and search engines. The MeSH terms "microRNAs" and "common variable immunodeficiency" were used. All research articles from inception to May 2020 were considered.

RESULTS

The literature data showed the involvement of two miRNAs in primary immunodeficiency: miR-142 and miR-155. Both of these miRNAs have been investigated through mice models, in which miR-142 and miR-155 were deleted. These knock-out (KO) mice models showed phenotypic analogies to CVID patients with hypogammaglobulinemia, adaptive immunodeficiency, polyclonal proliferation, lung disease, and enteric inflammation. miR-142 and miR-155 have been found to be involved in the following autoimmune and neoplastic clinical complications of CVID: Gastric cancer, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, natural killer/Tcell lymphoma (NKTCL), and immune thrombocytopenia.

CONCLUSIONS

miR-142 and miR-155 deregulation leads to similar CVID phenotypesin KO mice models. Although no data are available on the involvement of these miRNAs in human CVID, their dysregulation has been detected in human CVID comorbidities. The literature data show that miRNA sequences in murine models are comparable to those in humans; therefore, miR-142 and miR-155 involvement in human CVID could be hypothesized.