Current Molecular Medicine - Volume 21, Issue 7, 2021

Obesity is a global problem and the most common metabolic disorder leading to many associated diseases, such as arterial hypertension, ischemic heart disease, type 2 diabetes, certain types of cancer, impaired lipid and uric acid metabolism. The prevalence of obesity has risen globally in the past four decades in both children and adults, and it accounts for the rapid increase in the prevalence of diabetes. Currently, the study of thermogenic tissues, brown and beige adipose tissues, is of extreme value from the point of view of therapeutic potential for obesity and its associated diseases. An analogue of the glucagon-like peptide-1 (GLP-1) liraglutide, used in the treatment of type 2 diabetes, has been proven to have a positive effect on weight loss through appetite suppression. However, this mechanism of weight loss is not the only one involved. This article discusses the main molecular and cellular mechanisms of adipogenesis, as well as the effect of GLP-1 and its analogues, in particular liraglutide on this process through various transcription factors, signaling pathways, and hormones, including brown and beige adipose tissue. Also, the twincretins have had a positive effect on insulin resistance and fat beiging activation. The results of numerous studies have helped us to better understand the peripheral mechanisms of lipid metabolism regulation, and have demonstrated the effectiveness of GLP-1 analogues for the treatment of diabetes and obesity.

Male fertility is closely related to the normal function of the hypothalamicpituitary- testicular axis. The testis is an important male reproductive organ that secretes androgen and produces sperm through spermatogenesis. Spermatogenesis refers to the process by which spermatogonial stem cells (SSCs) produce highly differentiated spermatozoa and is divided into three stages: mitosis, meiosis and spermiogenesis. Spermatogenesis requires SSCs to strike a proper balance between self-renewal and differentiation and the commitment of spermatocytes to meiosis, which involves many molecules and signalling pathways. Abnormal gene expression or signal transduction in the hypothalamus and pituitary, but particularly in the testis, may lead to spermatogenic disorders and male infertility. The phosphoinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signalling pathway is involved in many stages of male reproduction, including the regulation of the hypothalamus-pituitarygonad (HPG) axis during spermatogenesis, the proliferation and differentiation of spermatogonia and somatic cells, and the regulation of sperm autophagy and testicular endocrine function in the presence of environmental pollutants, particularly endocrinedisrupting chemicals (EDCs). In the PI3K/AKT/mTOR signalling pathway, mTOR is considered the central integrator of several signals, regulating metabolism, cell growth and proliferation. In particular, mTOR plays an important role in the maintenance and differentiation of SSCs, as well as in regulating the redox balance and metabolic activity of Sertoli cells, which play an important role in nutritional support during spermatogenesis.

Helicobacter pylori, the most frequent pathogen worldwide that colonizes around 50% of the world’s population, causes important diseases such as gastric adenocarcinoma, chronic gastritis, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. In recent years, various studies have reported that H. pylori biofilm may be one of the critical barriers to the eradication of this bacterial infection. Biofilms inhibit the penetration of antibiotics, increase the expression of efflux pumps and mutations, multiple therapeutic failures, and chronic infections. Nanoparticles and natural products can demolish H. pylori biofilm by destroying the outer layers and inhibiting the initial binding of bacteria. Also, the use of combination therapies destroying extracellular polymeric substances decreases coccoid forms of bacteria and degrading polysaccharides in the outer matrix that lead to an increase in the permeability and performance of antibiotics. Different probiotics, antimicrobial peptides, chemical substances, and polysaccharides by inhibiting adhesion and colonization of H. pylori can prevent biofilm formation by this bacterium. Of note, many of the above are applicable to acidic pH and can be used to treat gastritis. Therefore, H. pylori biofilm may be one of the major causes of failure to eradication of infections caused by this bacterium, and antibiotics are not capable of destroying the biofilm. Thus, it is necessary to use new strategies to prevent recurrent and chronic infections by inhibiting biofilm formation.

The coronavirus disease 19 (COVID-19) is a highly pathogenic and transmissible viral disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in the city of Wuhan, Hubei Province, Central China and spread quickly around the world. The genome sequence of SARSCoV- 2 is phylogenetically related to bat-derived severe acute respiratory syndrome-like (SARS-like) coronaviruses; therefore bats could be the possible primary reservoirs. At present, there are no clinically approved vaccines or specific antiviral drugs for COVID- 19. However, several broad-spectrum antiviral drugs have been evaluated against COVID-19 in clinical studies and resulted in the improvement of patients. In this regard, other therapies such as antiviral drugs, antibodies, stem cells and plasma therapy are being studied. In the current study, we reviewed the emergence, pathogenicity and the genome structure of COVID-19 infection. The main focus of this study is on the therapeutic approaches that may be effective against SARS-CoV-2.

Osteosarcoma (OS) is a primary bone malignancy, which has a high incidence in children and adolescents. The affected cells and tissues show the properties of drug-resistance and the prognosis remains poor in OS; therefore, there is an essential need for novel therapeutic approaches. MicroRNAs (miRNAs) expression pattern has been established to be involved in the pathogenesis of OS. miRNAs are small non-coding RNA molecules, which negatively regulate gene expression at the post-transcriptional level. There are copious miRNAs that have a critical role in the onset of the disease, modulation of disease progression, and response to treatment. At the moment, the recently launched version 3.0 of Human MicroRNA Disease Database (HMDD v3.0) reports that 194 miRNAs are dysregulated in OS that might be involved in proliferation, migration, invasion, and epithelial-mesenchymal transition of tumor cells. The balance between oncogene and tumor suppressor miRNAs has vital importance in the final fate of the cell behaviors in OS. Additionally, networks of miRNAs may act in concert to induce oncogenic or tumor-suppressing properties during the initiation or the progression of OS. Up or down-regulation of these miRNAs affect the status of the disease during or after therapy. To date, over 40 miRNAs have been identified in OS disease that possess oncogenic or tumor-suppressing properties, and treatment approaches are trying to establish a proper level of such miRNAs in favor of OS therapy. The role of miRNAs involved in the pathogenesis of OS and their therapeutic potential are the reference points in this review article.

The coronavirus disease 2019 (COVID-19) is currently a new public health crisis threatening the world. This pandemic disease is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus has been reported to be originated in bats, and by yet unknown intermediary animals were transmitted to humans in China 2019. The SARS-CoV-2 spreads faster than its two ancestors, the SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV) but has reduced fatality. At present, the SARS-CoV-2 has caused about 1.16 million deaths with more than 43.4 million confirmed cases worldwide, resulting in a serious threat to public health globally with yet uncertain impact. The disease is transmitted by inhalation or direct contact with an infected person. The incubation period ranges from 1 to 14 days. COVID-19 is accompanied by various symptoms, including cough and fatigue. In most people, the disease is mild, but in some other people, such as in the elderly and people with chronic diseases, it may progress from pneumonia to a multi-organ dysfunction. Many people are reported asymptomatic. The virus genome is sequenced, but new variants are reported. Numerous biochemical aspects of its structure and function are revealed. To date, no clinically approved vaccines and/or specific therapeutic drugs are available to prevent or treat COVID-19. However, there are reported intensive researches on the SARS-CoV-2 to potentially identify vaccines and/or drug targets, which may help to overcome the disease. In this review, we discuss recent advances in understanding the molecular structure of SARS-CoV-2 and its biochemical characteristics.

Wide exploration of noninvasive tumor/cancer biomarkers has shed light on clinical diagnosis. However, many under-investigated biomarkers showed limited application potency due to low sensitivity and specificity, while extracellular vehicles (EVs) were gradually recognized as promising candidates. EVs are small vesicles transporting bioactive cargos between cells in multiple physiological processes and also in tumor/cancer pathogenesis. This review aimed to offer recent studies of EVs on structure, classification, physiological functions, as well as changes in tumor initiation and progression. Furthermore, we focused on advances of EVs and/or EV-related substances in cancer diagnosis, and summarized ongoing studies of promising candidates for future investigations.