Current Molecular Medicine - Volume 19, Issue 3, 2019

The malignancy of small cell lung cancer (SCLC) is the highest amongst all lung cancer types. It is characterized by rapid growth, early occurrence of distant sites metastasis, poor survival rates and is initially sensitive to chemotherapy and radiotherapy. However, most patients eventually relapse or disease progresses because of chemotherapy resistance. Because of lack of effective second-line therapies, the prognosis of SCLC patients is usually poor. For the development of novel therapies, it is necessary to understand the mechanisms of chemotherapy resistance in SCLC. The mechanism is complex, because multiple factors could lead to chemotherapy resistance. An overview of multiple events triggering the formation of chemotherapy resistance phenotypes of SCLC cells is discussed.

Purpose: Systemic lupus erythematosus (SLE) is a complex autoimmune disease with marked disparities in prevalence and disease severity among different ethnic groups. The purpose of this study is to characterize a Latin American cohort and identify genetic risk factors for developing SLE and its end-organ manifestations in this Latin Hispanic cohort. Methods: A total of 201 SLE cases and 205 non-diseased controls were recruited in the Dominican Republic (DR). Cases were defined according to the 1997 revised American College of Rheumatology criteria for the classification of SLE. Genomic DNA was prepared from whole blood and applied to genotyping analyses for 42 single nucleotide polymorphisms (SNPs) that have been implicated in autoimmune diseases, including SLE, in other ethnic populations. Data were analyzed by Fisher’s Exact Probability Test. Results: In this cohort, SNP rs9271366 (tag SNP for HLA-DRB1*15:01) confers the highest risk for SLE among the 13 MHC gene alleles that display association with SLE (p = 8.748E-10; OR = 3.5). Among the 26 non-MHC gene alleles analyzed, SNP rs2476601 in PTPN22 gene confers the highest risk for SLE (p = 0.0001; OR = 5.6). ITGAM, TNFSF4, TNIP1, STAT4, CARD11, BLK, and TNXB gene alleles were confirmed as SLE-susceptible alleles in the DR cohort. However, IRF5 and TNFAIP3 gene alleles, established risk factors for SLE in populations of European and Asian ancestry, are not significantly associated with SLE in this cohort. We also defined a novel HLA-DRA haplotype that confers an increased risk for lupus nephritis (LN) and alleles in HLA-DRA2 and TNFSF4 genes as genetic risk factors for developing neuropsychiatric (NP) SLE. Conclusion: Our data suggest that the Latin American population shares some common genetic risk factors for SLE as other populations, but also has distinct risk gene alleles that contribute to SLE susceptibility and development of LN and NPSLE. This is the first study focusing on genetic risk factors for SLE in the DR, a Latin American population that has never been characterized before

Purpose: Oxidative stress to retinal pigment epithelial (RPE) cells and inflammation are closely related to the pathogenesis of age-related macular degeneration (AMD). Celastrol is a natural compound isolated from the root of Tripterygium wilfordii. Celastrol has been shown to have potent anti-inflammatory and anti-tumor effects in multiple disease models. The objective of this study was to test the anti-oxidative effects of celastrol in RPE cells and to investigate the underlying mechanisms. Methods: ARPE-19 cells were treated with hydrogen peroxide (H2O2) and menadione alone or in combination with celastrol. Cell viability and apoptosis were examined by CCK-8 and TUNEL assay, respectively. The expression of Nrf2 and its target genes, such as GCLM and HO-1 was determined by Western blotting. The knockdown of Nrf2 was done by transfecting ARPE-19 cells with lentivirus encoding shRNA against Nrf2. The knockdown efficiency was determined by real-time quantitative PCR and Western blotting. Results: Treatment of ARPE-19 cells with celastrol significantly attenuated the toxic effects of both H2O2 and menadione. Treatment with celastrol enhanced the expression of transcription factor Nrf2 and its targets, GCLM and HO-1. Knockdown of Nrf2 expression by shRNA partially abolished the protective effects of celastrol. Chemical inhibition of glutathione synthesis by L-buthionine-S,R-sulfoximine (BSO) completely abolished the protective effects of celastrol against H2O2 and menadione-induced damage. However, chemical inhibition of HO-1 activity by ZnPPIX did not reduce the protective effects of celastrol. Conclusion: This study provides evidence that treatment of RPE cells with celastrol shows potent protective effects against oxidative insults via activation of Nrf2 signaling pathway and upregulation of GCLM expression. This finding suggests that celastrol might be used as a potential therapeutic agent for oxidative stress-related eyes diseases, such as AMD.

Background: The formation of hyperphosphorylated tau and the production of β-amyloid are thought to be critical steps contributing to the pathological mechanisms in Alzheimer’s disease (AD). However, there has been a long-lasting debate over their importance in the onset of AD. Recent studies have demonstrated that axonopathy is considered as an early neuropathological change of AD. However, the exact relationship between the development of axonopathy and the classic neuropathological changes such as senile plaques (SPs) and neurofibrillary tangles (NFTs) is unclear. Objective: The aim of this study was to investigate whether the formation of SPs and NFTs is associated with the development of axonal leakage. Method and Results: Here we show that the formation and development of axonal leakage - a novel axonopathy is an age-dependent process, accompanied by swellings of axons and varicosities and associated with chronic oxidative stress induced by thiamine deficient (TD) diet in Kunming mice. In an APP/PS1 transgenic mouse model of AD, axonal leakage appears at 3 months, becomes more obvious at 6 months and severe, beyond 1 year. We also show that slight axonal leakage is related to the formation of hyperphosphorylated tau, but not plaques, and that only severe axonal leakage accompanied by the extensive swollen axons and varicosities, and overproduction of β-amyloid leads to the formation of SPs and hyperphosphorylated tau. Conclusion: These data provide an explanation of the common origin and development of SPs and NFTs, and suggest that axonal leakage might be a key event in the development of the neuropathological processes in AD.

Background: Osteoporosis is a systemic skeletal disease characterized by low bone mineral density. Vitamin D metabolism may play a pivotal role in its pathophysiology. Objectives: To determine the association between Vitamin D receptor gene polymorphisms and bone density, as well as its relation to biochemical markers of bone turnover, in a healthy Saudi female population. Methods: A cross-sectional study was carried out at Taibah University, Madinah Region, Kingdom of Saudi Arabia. After receiving informed consent, blood samples from 300 subjects were collected to measure calcium, phosphorus, alkaline phosphatase, parathyroid hormone osteocalcin, and 1,25-OHD and perform genetic analysis of SNPs in vitamin D receptors (VDR) rs2228570, rs731236, and rs11568820. Results: There were significant differences between the CC, CT, and TT alleles of VDR rs2228570. Carrying the TT allele was associated with increased risks of decreased bone density and the presence of osteopenia with lower vitamin D3 levels (p≤0.001). The VDR rs731236 gene showed that CC allele carriers had significant risk of osteopenia. The AA genotype of rs11568820 showed lower levels of physical activity, bone mineral density, Z scores, serum osteocalcin, phosphorus, and parathyroid hormones. Conclusion: The presence of the TT allele of the SNP rs2228570 of the VDR gene and the SNP rs731236 of the CC genotype was associated with the presence of osteopenia and decreased bone mineral density alongside malfunctions of vitamin D.

Background: IL-2 cytokine is involved in HIV replication and is also known to cause hepatic injury. Polymorphisms in the IL-2 gene are associated with altered interleukin-2 production. Methods: Hence, we assessed the prevalence of IL-2-303G/T polymorphism in 165 HIV patients (34 with and 131without hepatotoxicity) and 155 healthy controls using the PCR-RFLP method. Results: In patients with hepatotoxicity, IL-2-303GT, -303GT+TT genotypes were less prevalent as compared to without hepatotoxicity and healthy controls (29.4% vs. 42.7%, 58.8% vs. 69.5%; 29.4% vs. 40.6%, 58.8% vs. 66.5%, respectively). In patients with hepatotoxicity using tobacco and alcohol, IL-2-303GT,-303TT genotypes were distributed higher as compared to non-users (42.9% vs. 25.9%, OR=8.52, 42.9% vs. 25.9%, OR=9.09, and 28.6% vs. 29.6%, OR=1.63, 42.9% vs. 25.9%, OR=2.93), while IL-2-303TT genotype occurred more often in HIV patients consuming alcohol (34.1% vs. 23.0%). Nevirapine users with hepatotoxicity overrepresented the IL-2-303GT,-303TT genotypes as compared to efavirenz (34.8% vs. 18.2%, OR=4.64, 34.8% vs. 18.2%, OR=3.88). Among nevirapine users, IL-2-303GT genotype was associated with susceptibility to the acquisition of hepatotoxicity with borderline significance (OR=4.24, P=0.06). HIV patients using nevirapine majorly represented the IL-2-303TT genotype (26.9% vs. 25.0%, OR=2.35) while HIV patients with nevirapine + alcohol usage presented the IL-2 -330TT genotype at a higher frequency (34.2%% vs. 23.5%, OR=1.51). In patients with hepatotoxicity using nevirapine + alcohol, the genotype IL-2 - 330TT was predominant (60.0% vs. 27.8%, OR=3.16). Conclusion: Thus, IL-2-303G/T polymorphism did not confer the susceptibility to ARV associated hepatotoxicity. However, IL-2-303G/T polymorphism with nevirapine usage may facilitate the risk for acquisition of ARV associated hepatotoxicity.

Background: We aimed at exploring biological functions of differentially expressed miRNAs during carcinogenesis, to identify miRNAs dysegulations involved in DNA repair mechanisms, and to evaluate potential of miRNAs as prognostic and diagnostic biomarkers for early lung adenocarcinomas (LAC). Methods: We obtained 21 LAC and paired adjacent normal formalin-fixed, paraffinembedded lung tissues from patients who underwent curative resection for stage I LAC. We compared expression levels of eight miRNAs involved in the DNA repair mechanism between LAC and adjacent tissues. Results: Expressions of Hsa-miR-9-5p, hsa-miR-24-3p, hsa-miR-125a-3p, hsa-miR- 125b-5p, hsa-miR-155-5p, and hsa-let-7a-5p were significantly up-regulated in stage I LAC tissues compared with those in the adjacent tissues. In addition, expressions of hsa-mir-9-5p, hsa-mir-24-3p, hsa-mir-125a-3p, hsa-mir-125b-5p, and hsa-mir-155-5p were significantly up-regulated in stage Ia LAC tissues, whereas expressions of hsa-mir- 125a-3p and hsa-mir-125b-5p were significantly up-regulated in stage Ib LAC tissues. Receiver operating characteristic (ROC) analysis revealed that AUROC of hsa-mir-125b- 5p was 0.875 (P < 0.001). Conclusion: Expression of hsa-mir-125b-5p could be used to distinguish LAC from adjacent tissues. Our result suggests that hsa-mir125b-5p can be a prognostic and diagnostic biomarker for LAC.

Background: Polydactyly, characterized by supernumerary digits in the upper or lower extremities, is the most common congenital digital abnormalities. It derives from the defective patterning of anteroposterior axis of the developing limb, with various etiology and clinical heterogeneity. The patients with post-axial polydactyly type A (PAPA) have the typical symptom of a well-formed supernumerary digit outside the fifth digit. Objective: The aim of present study was to identify the causative mutations of two unrelated Han Chinese patients with non-syndromic PAPA. Methods: Two unrelated Han Chinese patients and 100 ethnicity-matched, unrelated normal controls were recruited for this study. BGISEQ-500 exome sequencing was performed in the two patients, followed by validation in the patients and 100 controls by using Sanger sequencing. Results: Two mutations in the GLI family zinc finger 3 gene (GLI3), including a frameshift mutation c.3437_3453delTCGAGCAGCCCTGCCCC (p.L1146RfsX95) and a nonsense mutation c.3997C>T (p.Q1333X), were identified in two patients but were absent in the 100 healthy controls. Conclusion: The two GLI3 mutations, p.L1146RfsX95 and p.Q1333X, may account for non-syndromic PAPA in the two patients, respectively. The findings of this study may expand the mutational spectrum of GLI3-PAPA and provide novel insights into the genetic basis of polydactyly.