Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis最新文献

Background

Purpose

Methods

Results

Conclusion

Oral squamous cell carcinoma (OSCC) is primarily known as oral cancer (OC) that mostly occurs in mouth, lips and tongue. Mutations in some of the genes cause OC and some genes are risk factors for progression of OC. In this study, we analyzed the compositional features and pattern of codon usage in genes involved in OC using computational method as no work was reported yet. Compositional features suggested that the overall GC content was higher i.e. genes were GC rich. Effective number of codons (ENC) values ranged from 34.6 to 55.9 with a mean value of 49.03±4.22 representing low codon usage bias (CUB). Correspondence analysis (COA) suggested that the codon usage pattern was different in different genes. In genes associated with OC, highly significant correlation was observed between GC12 and GC3 (r=0.454, p<0.01) suggesting that directional mutation affected all the three codon positions. This is the first report on pattern of codon usage pattern on genes involved in OC, which not only alludes a new perspective for elucidating the mechanisms of biased usage of synonymous codons but also provide valuable clues for molecular genetic engineering.

Reactive aldehydes, for instance, formaldehyde and acetaldehyde, are important endogenous or environmental mutagens by virtue of their abilities to produce a DNA lesion called interstrand crosslink (ICL). Aldehyde-metabolizing enzymes such as aldehyde dehydrogenases (ALDHs) and the Fanconi anemia (FA) pathway constitute the main defense lines against aldehyde-induced genotoxicity. Biallelic mutations of genes in any one of the FA complementation groups can impair the ICL repair mechanism and cause FA, a heterogeneous disorder manifested by bone marrow failure (BMF), congenital abnormality and a strong predisposition to cancer. The defective ALDH2 polymorphism rs671 (ALDH2*2) is a known risk and prognostic factor for alcohol drinking-associated cancers. Recent studies suggest that it also promotes BMF and cancer development in FA, and its combination with alcohol dehydrogenase 5 (ADH5) mutations causes aldehyde degradation deficiency syndrome (ADDS), also known by its symptoms as aplastic anemia, mental retardation, and dwarfism syndrome. ALDH2*2 and another pathogenic variant in the alcohol-metabolizing pathway, ADH1B1*1, is prevalent among East Asians. Also, other ALDH2 genotypes with disease-modifying potentials have lately been identified in different populations. Therefore, it would be appropriate to summarize current knowledge of genotoxic aldehydes and defense mechanisms against them to shed new light on the pathogenic effects of ALDH2 variants together with other genetic and environmental modifiers on cancer and inherited BMF syndromes. Lastly, we also presented potential treatment strategies for FA, ADDS and cancer based on the manipulation of aldehyde-induced genotoxicity.

Despite considerable advancements in the diagnosis and treatment of LSCC, there has been no significant improvement in survival rate. Consequently, identifying molecular targets for this cancer is of paramount importance. HOXA1, a constituent of the homeobox transcription factor cluster, plays a role in the development of various types of cancer. Nevertheless, the specific function and mechanism of HOXA1 in LSCC remains unclear. This study aimed to clarify the impact of HOXA1 on the advancement of LSCC and uncover its underlying mechanism. Our findings indicate that HOXA1 exhibits a significantly elevated expression level in LSCC. Suppression of HOXA1 inhibited the proliferation of LSCC cells. Furthermore, the ablation of HOXA1 triggered the apoptosis of LSCC cells and inhibited EMT. Functionally, HOXA1 has a role in initiating the activation of the PI3K/AKT/mTOR pathway in LSCC cells. In summary, HOXA1 significantly contributes to the EMT of LSCC cells via the PI3K/AKT/mTOR signaling pathway, thereby facilitating the proliferation and motility of LSCC cells. Consequently, HOXA1 presents itself as a viable therapeutic target for LSCC interventions.

RAD51 is critical to the homologous recombination (HR) pathway that repairs DNA double strand breaks (DSBs) and protects replication forks (RFs). Previously, we showed that the S181P (SP) mutation in RAD51 causes defective RF maintenance but is proficient for DSB repair. Here we report that SP/SP female mice exhibit a shortened lifespan compared to +/+ females but not males. Histological analysis found that most mice in this study died from lymphoma, independent of genotype and sex. We propose that a potential cause for shortened lifespan in SP/SP females is due to the RF defect.

Background

Among primary liver cancers, HCC is the most prevalent. Small noncoding RNAs called miRNAs control the expression of downstream target genes to take part in a variety of physiological and pathological processes, including those related to cancer.

Methods

miR-129–2–3p and SEMA4C expression levels were assessed using RT-qPCR. The CCK-8, invasion, and wound healing assays were used to confirm the capacity of HCC cells for proliferation, invasion and migration respectively. Serum SEMA4C levels were detected via ELISA. The RIP and dual-luciferase reporter assays were used to confirm the existence of intergenic binding sites. Cell apoptosis assay and cell cycle assay were performed to detect the apoptosis rate and cycle distribution of cells, and WB was performed to detect the protein expression of SEMA4C, RhoA, ROCK1, E-cadherin, N-cadherin, and vimentin. Furthermore, cancer-inhibiting role of miR-129–2–3p were further confirmed by animal tests.

Results

miR-129–2–3p expression was reduced in HCC tissues and cells. Overexpression of miR-129–2–3p decreased the proliferation, invasion, migration, and EMT in HCC cells, whereas inhibition of miR-129–2–3p had the opposite effects. Our research also showed that SEMA4C was increased in HCC tissues, serum and cells, and that SEMA4C knockdown prevented HCC cell invasion, migration, proliferation, and EMT. Overexpression of SEMA4C reversed the inhibitory effect of miR-129–2–3p on HCC.

Conclusions

Overall, we discovered that through binding to SEMA4C, miR-129–2–3p regulates HCC cell proliferation, invasion, migration, and EMT.

Background

Multiple myeloma cancer stem cells (MMSC) have been considered as the leading cause of multiple myeloma (MM) drug resistance and eventual relapse, microRNAs (miRNAs) collectively participate in the progression of MM. However, the pathogenesis of miR-138 in MMSC is still not fully understood.

Objective

The intention of this study was to investigate the mechanism and role of miR-138 in multiple myeloma.

Method

Bone marrow samples and peripheral blood from patients and normal controls were collected. Use Magnet-based Cancer Stem Cell Isolation Kit to separate and extract MMSC. Real-time quantitative PCR (RT-qPCR) was carried out to determine mRNA level. Western blot was applied to detect protein levels. MTT and flow cytometry were conducted to examine the proliferation and apoptosis of MMSC. Finally, dual-luciferase reporter gene assays were performed to confirm that paired box 5 (PAX5) is a direct target for miR-138.

Results

Compared with normal group, the expression of miR-138 in patients was significantly up-regulated, and the expression of miR-138 was in a negative correlation with PAX5. Additionally, downregulated miR-138 facilitated the apoptosis and inhibited the proliferation of MMSC in vitro and in vivo. Downregulated miR-138 moderated the expression of PAX5, Bcl-2, Bax, and Caspase-3. PAX5 was a direct target of miR-138.

Conclusion

Taken together, miR-138 plays a carcinogenic role in MM, and miR-138 adjusted the proliferation and apoptosis of MMSC by targeting PAX5. miR-138 has the probability of becoming a new medicinal target for the treatment of MM.

Homologous recombination (HR) is essential for repair of DNA double-strand breaks (DSBs) and restart of stalled or collapsed replication forks. Most cancers are characterized by mutations in components of the DSB repair pathways. Redundant DSB repair pathways exist in eukaryotes from yeast to humans and recent evidence has shown that complete loss of HR function appears to be lethal. Recent evidence has also shown that cancer cells with mutations in one DSB repair pathway can be killed by inhibiting one or more parallel pathways, a strategy that is currently aggressively explored as a cancer therapy. KDM4B is a histone demethylase with pleiotropic functions, which participates in preparing DSBs for repair by contributing to chromatin remodeling. In this report we carried out a pan-cancer analysis of KDM4B mutations with the goal of understanding their distribution and interaction with other DSB genes. We find that although KDM4B mutations co-occur with DSB repair genes, most KDM4B mutations are not drivers or pathogenic. A sequence conservation analysis from yeast to humans shows that highly conserved residues are resistant to mutation. Finally, all mutations occur in a heterozygous state. A single mutation, R986L, was predicted to significantly affect protein structure using computational modeling. This analysis suggests that KDM4B makes contributions to DSB repair but is not a key player.

Background

Prostate cancer (PCa), a prevalent malignancy worldwide, is frequently identified in advanced stages due to the absence of distinctive early symptoms, thereby culminating in the development of chemotherapy-induced drug resistance. Exploring novel resistance mechanisms and identifying new therapeutic agents can facilitate the advancement of more efficacious strategies for PCa treatment.

Methods

Bioinformatics analysis was employed to investigate the expression of FOXG1 in PCa tissues. Subsequently, qRT-PCR was utilized to validate FOXG1 mRNA expression levels in corresponding PCa cell lines. FOXG1 knockdown was performed, and cell proliferation was assessed using CCK-8 assays, while cell migration and invasion capabilities were evaluated through wound healing and Transwell assays. Western blot and Seahorse analyzer were used to measure oxidative phosphorylation (OXPHOS) levels. Additionally, to explore potential approaches to alleviate PCa drug resistance, this study assessed the impact of biologically active saikosaponin-d (SSd) on PCa malignant progression and resistance by regulating FOXG1 expression.

Results

FOXG1 exhibited high expression in PCa tissues and cell lines. Knockdown of FOXG1 inhibited the proliferation, migration, and invasion of PCa cells, while FOXG1 overexpression had the opposite effect and promoted OXPHOS levels. The addition of an OXPHOS inhibitor prevented this outcome. Finally, SSd was shown to suppress FOXG1 expression and reverse docetaxel resistance in PCa cells through the OXPHOS pathway.

Conclusion

This work demonstrated that SSd mediated FOXG1 to reverse malignant progression and docetaxel resistance in PCa through OXPHOS.