Genes and Environment最新文献

Background: Long non-coding RNA (lncRNA) is a group of RNA transcripts that contribute to tumor development by post-transcriptionally regulating cancer-related genes. Nasopharyngeal carcinoma (NPC) is an epithelial tumor that occurs in the nasopharynx and is common in North Africa and Southeast Asia. The study investigated the functions of lncRNA TMPO-AS1 in NPC cell proliferation and apoptosis as well as its related competing endogenous RNA (ceRNA) mechanism.

Methods: Candidate microRNA and genes that may regulated by TMPO-AS1 were predicted with the bioinformatic tool starBase. TMPO-AS1 expression in NPC tissue, cells, nuclear part, and cytoplasmic part was measured by RT-qPCR. MTT assay, EdU assay, and flow cytometry analysis were carried out to evaluate NPC cell viability, proliferation, and apoptosis, respectively. RNA immunoprecipitation assay and luciferase reporter assay were conducted to detect the binding between TMPO-AS1 and let-7c-5p or that between let-7c-5p and BCAT1.

Results: TMPO-AS1 and BCAT1 showed high expression in NPC tissue and cells, while let-7c-5p was downregulated in NPC. The silencing of TMPO-AS1 suppressed NPC cell proliferation while promoting cell apoptosis. Moreover, TMPO-AS1 interacted with let-7c-5p and negatively regulated let-7c-5p expression. BCAT1 was a target of let-7c-5p and was inversely regulated by let-7c-5p in NPC cells. The repressive impact of TMPO-AS1 knockdown on NPC cell growth was countervailed by overexpressed BCAT1.

Conclusion: TMPO-AS1 accelerates NPC cell proliferation and represses cell apoptosis by interacting with let-7c-5p to regulate BCAT1 expression.

Background: Rosmarinic acid (RA) has a wide range of beneficial effects on human health. On the other hand, RA has been reported to induce metal-mediated reactive oxygen species (ROS) generation and DNA damage. However, its mechanism remains unknown. In this study, to clarify the underlying mechanism, we analyzed metal-mediated DNA damage in isolated DNA treated with RA and its analog isorinic acid.

Results: RA plus Cu(II), but not Fe(III), significantly increased 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, an indicator of oxidative DNA damage, in calf thymus DNA. Furthermore, a comparison of the 8-oxodG formation induced by RA and its analog isorinic acid suggested that the catechol groups in RA could be associated with their abilities to form 8-oxodG. Interestingly, the 8-oxodG formation induced by RA and isorinic acid plus Cu(II) was markedly enhanced by the addition of NADH, an endogenous reductant. To elucidate the mechanism of RA plus Cu(II)-induced oxidative DNA damage, we examined DNA damage in ³²P-labeled DNA treated with RA in the presence of Cu(II). RA plus Cu(II) caused DNA cleavage, which was enhanced by piperidine treatment, suggesting that RA causes not only DNA strand breakage but also base modification. RA plus Cu(II)-induced DNA damage was inhibited by catalase (H₂O₂ scavenger), bathocuproine (Cu(I) chelator), and methional (scavenger of a variety of ROS other than ^•OH) but not by typical ^•OH scavengers and SOD, indicating the involvement of H₂O₂, Cu(I), and ROS other than ^•OH. DNA cleavage site analysis showing RA-induced site-specific DNA damage (frequently at thymine and some cytosine residues) supports the involvement of ROS other than ^•OH, because ^•OH causes DNA cleavage without site specificity. Based on these results, Cu(I) and H₂O₂ generation with concomitant RA autoxidation could lead to the production of Cu(I)-hydroperoxide, which induces oxidative DNA damage. o-Quinone and o-semiquinone radicals are likely to be again reduced to RA by NADH, which dramatically increases oxidative DNA damage, particularly at low concentrations of RA.

Conclusions: In this study, physiologically relevant concentrations of RA effectively induced oxidative DNA damage in isolated DNA through redox cycle reactions with copper and NADH.

Background: Sinonasal adenocarcinoma is a rare cancer, encompassing two different entities, the intestinal-type sinonasal adenocarcinoma (ITAC) and the non-intestinal-type sinonasal adenocarcinoma (non-ITAC). Occurrence of ITAC is strongly associated with exposure to hardwood dusts. In countries with predominant exposure to softwood dust the occurrence of sinonasal adenocarcinomas is lower and the relative amount of non-ITACs to ITACs is higher. The molecular mechanisms behind the tumorigenic effects of wood dust remain largely unknown.

Methods: We carried out whole-genome sequencing of formalin-fixed paraffin-embedded (FFPE) samples of sinonasal adenocarcinomas from ten wood dust-exposed and six non-exposed individuals, with partial tobacco exposure data. Sequences were analyzed for the presence of mutational signatures matching COSMIC database signatures. Driver mutations and CN variant regions were characterized.

Results: Mutation burden was higher in samples of wood dust-exposed patients (p = 0.016). Reactive oxygen species (ROS) damage-related mutational signatures were almost exclusively identified in ITAC subtype samples (p = 0.00055). Tobacco smoke mutational signatures were observed in samples of patients with tobacco exposure or missing information, but not in samples from non-exposed patients. A tetraploidy copy number (CN) signature was enriched in ITAC subtype (p = 0.042). CN variation included recurrent gains in COSMIC Cancer Gene Census genes TERT, SDHA, RAC1, ETV1, PCM1, and MYC. Pathogenic variants were observed most frequently in TP53, NF1, CHD2, BRAF, APC, and LRP1B. Driver mutations and copy number gains did not segregate by subtype.

Conclusions: Our analysis identified distinct mutational characteristics in ITAC and non-ITAC. Mutational signature analysis may eventually become useful for documentation of occupation-related cancer, while the exact mechanisms behind wood dust-driven carcinogenesis remain elusive. The presence of homologous recombination deficiency signatures implies a novel opportunity for treatment, but further studies are needed.

Background: Gastric cancer is the sixth most frequently diagnosed cancer and third in causing cancer-related death globally. The most frequently mutated gene in human cancers is TP53, which plays a pivotal role in cancer initiation and progression. In Africa, particularly in Rwanda, data on TP53 mutations are lacking. Therefore, this study intended to obtain TP53 mutation status in Rwandan patients with gastric cancer.

Results: Formalin-fixed paraffin-embedded tissue blocks of 95 Rwandan patients with histopathologically proven gastric carcinoma were obtained from the University Teaching Hospital of Kigali. After DNA extraction, all coding regions of the TP53 gene and the exon-intron boundary region of TP53 were sequenced using the Sanger sequencing. Mutated TP53 were observed in 24 (25.3%) of the 95 cases, and a total of 29 mutations were identified. These TP53 mutations were distributed between exon 4 and 8 and most of them were missense mutations (19/29; 65.5%). Immunohistochemical analysis for TP53 revealed that most of the TP53 missense mutations were associated with TP53 protein accumulation. Among the 29 mutations, one was novel (c.459_477delCGGCACCCGCGTCCGCGCC). This 19-bp deletion mutation in exon 5 caused the production of truncated TP53 protein (p.G154Wfs*10). Regarding the spectrum of TP53 mutations, G:C > A:T at CpG sites was the most prevalent (10/29; 34.5%) and G:C > T:A was the second most prevalent (7/29; 24.1%). Interestingly, when the mutation spectrum of TP53 was compared to three previous TP53 mutational studies on non-Rwandan patients with gastric cancer, G:C > T:A mutations were significantly more frequent in this study than in our previous study (p = 0.013), the TCGA database (p = 0.017), and a previous study on patients from Hong Kong (p = 0.006). Even after correcting for false discovery, statistical significance was observed.

Conclusions: Our results suggested that TP53 G:C > T:A transversion mutation in Rwandan patients with gastric cancer is more frequent than in non-Rwandan patients with gastric cancer, indicating at an alternative etiological and carcinogenic progression of gastric cancer in Rwanda.

Background: Carbendazim (methyl 2-benzimidazolecarbamate, CASRN: 10605-21-7) exhibits spindle poisoning effects and is widely used as a fungicide. With respect to genotoxicity, carbendazim is deemed to be non-mutagenic in vitro, but it causes indicative DNA damage in vivo and chromosome aberrations in vitro and in vivo. In this study, we examined the mutagenicity of carbendazim in vivo.

Results: MutaMice were treated with carbendazim orally at doses of 0 (corn oil), 250, 500, and 1,000 mg/kg/day once a day for 28 days. A lacZ assay was used to determine the mutant frequency (MF) in the liver and glandular stomach of mice. MutaMice were administered up to the maximum dose recommended by the Organization for Economic Co-operation and Development Test Guidelines for Chemicals No. 488 (OECD TG488). The lacZ MFs in the liver and glandular stomach of carbendazim-treated animals were not significantly different from those in the negative control animals. In contrast, positive control animals exhibited a significant increase in MFs in both the liver and glandular stomach.

Conclusions: Carbendazim is non-mutagenic in the liver and glandular stomach of MutaMice following oral treatment.

The prevalence of cancer is increasing globally, and Malaysia is no exception. The exposome represents a paradigm shift in cancer research, emphasizing the importance of a holistic approach that considers the cumulative effect of diverse exposures encountered throughout life. The exposures include dietary factors, air and water pollutants, occupational hazards, lifestyle choices, infectious agents and social determinants of health. The exposome concept acknowledges that each individual's cancer risk is shaped by not only their genetic makeup but also their unique life experiences and environmental interactions. This comprehensive review was conducted by systematically searching scientific databases such as PubMed, Scopus and Google Scholar, by using the keywords "exposomes (environmental exposures AND/OR physical exposures AND/OR chemical exposures) AND cancer risk AND Malaysia", for relevant articles published between 2010 and 2023. Articles addressing the relationship between exposomes and cancer risk in the Malaysian population were critically evaluated and summarized. This review aims to provide an update on the epidemiological evidence linking exposomes with cancer risk in Malaysia. This review will provide an update for current findings and research in Malaysia related to identified exposomes-omics interaction and gap in research area related to the subject matter. Understanding the interplay between complex exposomes and carcinogenesis holds the potential to unveil novel preventive strategies that may be beneficial for public health.

Background: Previously, we have reported on the two curcuminoid analogues with piperidone derivatives, namely FLDP-5 and FLDP-8 have more potent anti-proliferative and anti-migration effects than curcumin. In this study, we further investigated the mode of cell death and the mechanism involved in the cell death process induced by these analogues on human glioblastoma LN-18 cells.

Results: The FLDP-5 and FLDP-8 curcuminoid analogues induced LN-18 cell death through apoptosis in a concentration-dependent manner following 24 h of treatment. These analogues induced apoptosis in LN-18 cells through significant loss of mitochondrial mass and mitochondrial membrane potential (MMP) as early as 1-hour of treatment. Interestingly, N-acetyl-l-cysteine (NAC) pretreatment did not abolish the apoptosis induced by these analogues, further confirming the cell death process is independent of ROS. However, the apoptosis induced by the analogues is caspases-dependent, whereby pan-caspase pretreatment inhibited the curcuminoid analogues-induced apoptosis. The apoptotic cell death progressed with the activation of both caspase-8 and caspase-9, which eventually led to the activation of caspase-3, as confirmed by immunoblotting. Moreover, the existing over-expression of miRNA-21 in LN-18 cells was suppressed following treatment with both analogues, which suggested the down-regulation of the miRNA-21 facilitates the cell death process.

Conclusion: The FLDP-5 and FLDP-8 curcuminoid analogues downregulate the miRNA-21 expression and induce extrinsic and intrinsic apoptotic pathways in LN-18 cells.

Background: A micronucleus test is generally used to evaluate the genotoxic potential of chemicals. Exaggerated erythropoiesis, as occurs following bleeding, may induce an unexpected increase in micronucleus frequency. This false positive result would be typical in a genotoxicity study due to the enhanced progression of the cell cycle that restores decreased blood cells. The cyclin-dependent kinase (CDK) family is known to play an essential role in preventing genomic instability. Conversely, a selective CDK4/6 inhibitor PD0332991, clinically named Palbociclib, is reported to have genotoxic potential, shown by positive results in both in vitro and in vivo micronucleus studies. To clarify the mechanism by which cell cycle arrest induced by a CDK4/6 inhibitor increases micronucleus frequency, we investigated the positive results of the bone marrow micronucleus test conducted with PD0332991.

Results: Rats treated with PD0332991 exhibited increased micronucleus frequency in an in vivo bone marrow micronucleus test whereas it was not increased by treatment in human lymphoblastoid TK6 cells. In addition, all other genotoxicity tests including the Ames test and the comet assay showed negative results with PD0332991. Interestingly, PD0332991 treatment led to an increase in erythrocyte size in rats and affected the size distribution of erythrocytes, including the micronucleus. The mean corpuscular volume of reticulocytes (MCVr) in the PD0332991 treatment group was significantly increased compared to that of the vehicle control (83.8 fL in the PD0332991, and 71.6 fL in the vehicle control.). Further, the average micronucleated erythrocytes (MNE) size of the PD0332991 group and vehicle control was 8.2 and 7.3 µm, respectively. In the histogram, the vehicle control showed a monomodal distribution with a peak near 7.3 µm. In contrast, the PD0332991 group showed a bimodal distribution with peaks around 7.5 and 8.5 µm. Micronucleated erythrocytes in the PD0332991 group were significantly larger than those in the vehicle control. These results suggest that the increase in micronucleus frequency induced by the CDK4/6 inhibitor is not due to genotoxicity, but is attributable to disturbance of the cell cycle, differentiation, and enucleation of erythroblasts.

Conclusions: It was suggested that the positive outcome of the in vivo bone marrow micronucleus test resulting from treatment with PD0332991 could not be attributed to its genotoxicity. Further studies to clarify the mechanism of action can contribute to the development of drug candidate compounds lacking intrinsic genotoxic effects.

Background: Gastric cancer (GC) is a common malignancy with its morbidity increasing worldwide. Hence, it is imperative to develop effective treatments. Studies have shown that metformin has potential antitumor effects. The objective of this study was to probe the antitumor mechanism of metformin in GC.

Methods: The expression of ADAMTS12 in GC tissues and its enrichment pathways were analyzed by bioinformatics methods. ADAMTS12 expression in GC cells was assessed by qRT-PCR. Cell viability and proliferation were analyzed by CCK-8 and colony formation assays, respectively. Extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of GC cells in different treatment groups were analyzed by Seahorse XP 96, and glycolysis metabolites were detected by corresponding kits. Western blot was employed to analyze the level of glycolysis pathway related protein HK-2, and cell functional assays were conducted to verify the functions of metformin on GC cells. A xenograft model was constructed to validate the inhibitory role of metformin in GC.

Results: ADAMTS12 expression was elevated in GC tissues/cells and concentrated in glycolysis pathway. Cell functional assays found that ADAMTS12 promoted the proliferation and glycolysis of GC cells. Rescue experiments showed that metformin could reduce the promoting effect of ADAMTS12 overexpression on the proliferation and glycolysis of GC cells. In vivo studies confirmed that metformin suppressed the proliferation and glycolysis process via ADAMTS12 in GC cells.

Conclusion: Metformin can repress the proliferation and glycolysis of GC cells via ADAMTS12. The results suggest the potential of ADAMTS12 being a target for the metformin therapy of GC.