Molecular Mechanisms Of Resistance Research Articles

AmiRNA Technology Enhances Tomato Disease Resistance by Suppressing Plant-Pathogen Interaction Pathways through Inhibiting TYLCV Replication.

Tomato yellow leaf curl virus disease has seriously threatened the quality and yield of tomatoes. In this study, we investigated the role of amiRNA technology in disease resistance in tomatoes (cherry tomato and large-fruited tomato) and analyzed the physiological and molecular mechanisms of disease resistance in transgenic plants. TYLCV contains six functional genes, of which the C1, C2, and V1 genes have more phosphorylation sites and glycosylation sites, and the protein structure is more complex. The virus replication was inhibited, the peroxidation of membrane lipids was reduced, and disease resistance was enhanced in all transgenic cherry tomato (J6) plants in which the C1, C2, and V1 genes were silenced, respectively. Similarly, silencing of the C1 gene enhanced disease resistance in large-fruited tomatoes. In conclusion, amiRNA technology hinders viral replication, leading to reduced activity of the tomato plant-pathogen interaction pathway and weakening tomato-virus interactions, thereby improving disease resistance.

Integrating Physiology, Transcriptome, and Metabolome Analyses Reveals the Drought Response in Two Quinoa Cultivars with Contrasting Drought Tolerance.

Quinoa (Chenopodium quinoa Willd.) is an annual broadleaf plant belonging to the Amaranthaceae family. It is a nutritious food crop and is considered to be drought-tolerant, but drought is still one of the most important abiotic stress factors limiting its yield. Quinoa responses to drought are related to drought intensity and genotype. This study used two different drought-responsive quinoa cultivars, LL1 (drought-tolerant) and ZK1 (drought-sensitive), to reveal the important mechanisms of drought response in quinoa by combining physiological, transcriptomic, and metabolomic analyses. The physiological analysis indicated that Chla/Chlb might be important for drought tolerance in quinoa. A total of 1756 and 764 differentially expressed genes (DEGs) were identified in LL1 and ZK1, respectively. GO (Gene Ontology) enrichment analysis identified 52 common GO terms, but response to abscisic acid (GO:0009737) and response to osmotic stress (GO:0006970) were only enriched in LL1. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis revealed that glycerophospholipid metabolism (ko00564) and cysteine and methionine metabolism (ko00270) ranked at the top of the list in both cultivars. A total of 1844 metabolites were identified by metabolomic analysis. "Lipids and lipid-like" molecules had the highest proportions. The DEMs in LL1 and ZK1 were mainly categorized 6 and 4 Human Metabolome Database (HMDB) superclasses, respectively. KEGG analysis revealed that the 'α-linolenic acid metabolism' was enriched in both LL1 and ZK1. Joint KEGG analysis also revealed that the 'α-linolenic acid metabolism' pathway was enriched by both the DEGs and DEMs of LL1. There were 17 DEGs and 8 DEMs enriched in this pathway, and methyl jasmonate (MeJA) may play an important role in the drought response of quinoa. This study will provide information for the identification of drought resistance in quinoa, research on the molecular mechanism of drought resistance, and genetic breeding for drought resistance in quinoa.

The Mediator complex subunit MoMed15 plays an important role in conferring sensitivity to isoprothiolane by modulating xenobiotic metabolism in M. oryzae.

Rice blast caused by Magnaporthe oryzae is one of the most economically important rice diseases. Fungicides such as isoprothiolane (IPT) have been used extensively for rice blast control, but resistance to IPT in M. oryzae is an emerging threat. In this study, molecular mechanisms of resistance in IPT-resistant mutants were identified. Through whole-genome sequencing and genetic transformation, we identified the gene MoMed15, encoding a transcriptional glutamine-rich co-activator Mediator complex subunit, in which mutations or deletion resulted in moderate IPT resistance. Further research found that MoMed15 physically interacted with the IPT resistance regulatory factor MoIRR to simultaneously regulate both MoIRR expression and the expression of multiple xenobiotic-metabolizing enzymes in response to IPT stress. We hypothesize that some xenobiotic-metabolizing enzymes enhance IPT toxicity by modifying the IPT structure. Variation of MoMed15 affected the recruitment of the transcriptional Mediator complex and decreased the expression of these xenobiotic-metabolizing enzymes, resulting in moderate IPT resistance. We also found that MoPGR1, encoding a protein that activates cytochrome P450 enzymes, was essential to confer IPT sensitivity, and its expression was directly regulated by MoIRR.IMPORTANCEIsoprothiolane (IPT) has been used extensively for the management of rice blast disease and IPT-resistant subpopulations have emerged in Chinese rice fields. The emergence of resistant pathogen populations has led to a steep increase in fungicide use, increasing pesticide risk for the applicator and the environment. The molecular mechanisms of IPT resistance in M. oryzae remain elusive. In this study, we demonstrated that transcriptional co-activator MoMed15 interacts with IPT resistance regulator MoIRR to recruit the Mediator complex, which promotes the expression of xenobiotic-metabolizing enzymes, leading to exacerbated IPT toxicity. The MoMed15 could be used for IPT resistance detection in rice fields.

DDDR-16. SORTING TO ENRICH FOR CHEMOTHERAPEUTIC-RESISTANT GLIOMA CELLS BASED ON UNIQUE MEMBRANE PROPERTIES

Abstract Glioblastoma, astrocytoma, and oligodendroglioma comprise a class of aggressive and deadly brain tumors called diffuse gliomas. Around 20,000 glioma cases are diagnosed yearly in the US alone. The current standard chemotherapy treatment, temozolomide (TMZ), is insufficient as the 5-year survival rate of glioblastoma patients is as low as 8%. This is due to the presence of TMZ-resistant cells within tumors that lead to chemoresistance and tumor recurrence. Thus, studying the molecular properties of TMZ-resistant cells would enable more effective means of targeting them and thus improve patient outcomes. We leveraged dielectrophoresis (DEP), a phenomenon by which non-uniform electric fields induce differential movement of cells, as a novel label-free technique to sort glioma cells based on their membrane electrophysiological properties. We were able to successfully use DEP to sort cells from glioblastoma and oligodendroglioma established cell lines, which yielded fractions that differed in membrane capacitance, the membrane’s ability to store charge. Interestingly, the DEP-sorted cell fractions also exhibited significant differences in TMZ resistance, indicating that we were able to use DEP to enrich for TMZ-resistant cells. Further, the differences in TMZ resistance were coupled with their membrane capacitance differences. Because we previously found that changes in membrane capacitance were linked to differences in glycosylation, we utilized lectin analysis to assess glycan expression of DEP-sorted oligodendroglioma cells. Our data show that TMZ-resistant oligodendroglioma cells enriched from DEP sorting had reduced levels of mannose glycans compared to less TMZ-resistant fractions. Collectively, our novel findings demonstrate (a) TMZ-resistant glioma cells can be enriched by DEP, and (b) TMZ resistance is correlated with membrane capacitance and cell surface glycosylation. These findings could enable further characterization of TMZ-resistant cells to better understand molecular mechanisms of TMZ resistance and the development of more effective treatment strategies for gliomas through targeting membrane properties such as glycosylation.

Comparative transcriptome analysis of maize (Zea mays L.) seedlings in response to copper stress.

Copper (Cu) is considered one of the major heavy metal pollutants in agriculture, leading to reductions in crop yield. To reveal the molecular mechanisms of resistance to copper stress in maize (Zea mays L.) seedlings, transcriptome analysis was conducted on the hybrid variety Zhengdan 958 exposed to 0 (control), 5, and 10 mM Cu stress using RNA-seq. In total, 619, 2,685, and 1,790 differentially expressed genes (DEGs) were identified compared to 5 mM versus 0 mM Cu, 10 mM versus 0 mM Cu, and 10 mM versus 5 mM Cu, respectively. Functional categorization of DEGs according to Gene Ontology revealed that heme binding, defense response, and multiorganism processes were significantly enriched under copper stress. Additionally, Kyoto Encyclopedia of Genes and Genomes enrichment analysis suggested that the copper stress response is mediated by pathways involving phenylpropanoid biosynthesis, flavonoid biosynthesis, and glutathione metabolism, among others. The transcriptome data demonstrated that metabolite biosynthesis and glutathione metabolism play key roles in the response of maize seedlings to copper stress, and these findings provide valuable information for enhancing copper resistance in maize.

Genome-Wide Analysis of the Serine Carboxypeptidase-like (SCPL) Protein Family of Bitter Gourd and Functional Validation of McSCPL22 in Fusarium oxysporum f. sp. Momordicae (FOM) Resistance.

Bitter gourd is increasingly being recognized for its value as a vegetable and medicinal use, but the molecular mechanisms of pathogen resistance remain relatively poorly understood. The serine carboxypeptidase-like (SCPL) protein family plays a key role in plant growth, pathogen defense, and so on. However, a comprehensive identification and functional characterization of the SCPL gene family has yet to be conducted in bitter melon. In this study, 32 SCPL genes were identified in bitter gourd and divided into three classes. The number of SCPL genes contained in the three clusters was 7, 7, and 18, respectively. Most SCPL gene promoters contain cis-acting elements with light, hormone, and stress responses. The RNA sequencing data showed that the expression of several SCPL genes changed significantly after pathogen infection. In particular, expression of the McSCPL4, 10, 17, 22, and 25 genes increased substantially in the resistant varieties after infection, and their expression levels were higher than those in the susceptible varieties. These results suggested that genes such as McSCPL4, 10, 17, 22, and 25 may play a significant role in conferring resistance to fungal infections. Moreover, the expression levels of the McSCPL10, 17, 22, 23, and 25 genes were likewise significantly changed after being induced by salicylic acid (SA) and jasmonic acid (JA). In situ hybridization showed that McSCPL22 was expressed in the vascular tissues of infected plants, which largely overlapped with the location of Fusarium oxysporum f. sp. Momordicae (FOM) infection and the site of hydrogen peroxide production. Our results showed that McSCPL22 may be involved in the regulation of the SA and JA pathways and enhance resistance to FOM in bitter gourd plants. This is the first study to perform SCPL gene family analysis in bitter gourd. McSCPL22 may have the potential to enhance FOM resistance in bitter gourd, and further investigation into its function is warranted. The results of this study may enhance the yield and molecular breeding of bitter gourd.

Research Progress on the Genetic and Molecular Mechanisms of Cucumber (Cucumis sativus L.) Powdery Mildew Resistance

As a common fungal disease, powdery mildew (PM) is one of the main diseases that harm the growth and development of cucumbers. Understanding the types of pathogenic fungus and analysis of the genetic and molecular mechanisms of cucumber resistance to PM at the molecular level are important when breeding disease-resistant varieties. The present review summarizes the hazards, prevention, and control of PM, and it discusses resistance inheritance rules, molecular markers, quantitative trait locus (QTL) mapping, gene cloning, omics, and gene editing technology, providing research insights on cucumber breeding varieties resistant to PM.

Analysis of molecular mechanisms of delafloxacin resistance in Escherichia coli

In this study delafloxacin resistance mechanisms in Escherichia coli strains were analyzed. Delafloxacin is a new fluoroquinolone, that is approved for clinical application however, resistance against this agent is scarcely reported. In our study 37 E. coli strains were included and antimicrobial susceptibility testing was performed for ciprofloxacin, delafloxacin, levofloxacin, moxifloxacin, ceftazidime, cefotaxime, imipenem. Six delafloxacin resistant E. coli strains were selected for whole-genome sequencing and all of them exhibited resistance to other fluoroquinonlones and showed an extended-spectrum beta-lactamase phenotype. The six delafloxacin resistant E. coli strains belonged to different sequence types (STs) namely, ST131 (2 strains), ST57 (2 strains), ST162 and ST15840. Each delafloxacin resistant strain possessed multiple mutations in quinolone resistance-determining regions (QRDRs). Notably, three mutations in gyrA Ser83Leu, Asp87Asn and parC Ser80Ile were in strains of ST162, ST57 and ST15840. However, the two strains of ST131 carried five combined mutations namely, gyrA Ser83Leu, Asp87Asn, parC Ser80Ile, Glu84Val, parE Ile549Leu. Association of delafloxacin resistance and production of CTX-M-15 in ST131, CMY-2 in ST162 and ST15840 was detected. In this study a new ST, ST15840 of clonal complex 69 was identified. Our results demonstrate, that at least three mutations in QRDRs are required for delafloxacin resistance in E. coli.

Based proteomics analyses reveal response mechanisms of Apis mellifera (Hymenoptera: Apidae) against the heat stress.

Heat stress can significantly affect the survival, metabolism, and reproduction of honeybees. It is important to understand the proteomic changes of honeybees under heat stress to understand the molecular mechanism behind heat resistance. However, the proteomic changes of honeybees under heat stress are poorly understood. We analyzed the proteomic changes of Apis mellifera Ligustica (Hymenoptera: Apidae) under heat stress using mass spectrometry-based proteomics with TMT (Tandem mass tags) stable isotope labeling. A total of 3,799 proteins were identified, 85 of which differentially abundance between experimental groups. The most significant categories affected by heat stress were associated with transcription and translation processes, metabolism, and stress-resistant pathways. We found that heat stress altered the protein profiles in A. mellifera, with momentous resist proteins being upregulated in heat groups. These results show a proof of molecular details that A. mellifera can respond to heat stress by increasing resist proteins. Our findings add research basis for studying the molecular mechanisms of honeybees' resistance to heat stress. The differentially expressed proteins identified in this study can be used as biomarkers of heat stress in bees, and provide a foundation for future research on honeybees under heat stress. Our in-depth proteomic analysis provides new insights into how bees cope with heat stress.

Exploring the Molecular Mechanisms of Resistance to Prochloraz by Lasiodiplodia theobromae Isolated from Mango.

Mango stem-end rot caused by Lasiodiplodia theobromae is a major postharvest disease in China. Prochloraz is commonly used for disease control in mango orchards and in storage. However, prochloraz resistance has been detected in L. theobromae. This study aimed to explore the underlying mechanisms responsible for prochloraz resistance in L. theobromae. The results show that no point mutation in the target gene LtCYP51 of the prochloraz-resistant L. theobromae strain was detected, but the expression was upregulated significantly. Additionally, the full-length sequences of the cytochrome P450 gene CYP55A3 were successfully amplified and identified from L. theobromae, and the qRT-PCR results confirm that CYP55A3 was significantly upregulated after treatment with prochloraz. The knockout mutant of the CYP55A3 presented significantly lower gene expression levels than the wild-type strain HL02, with a 16.67-fold reduction, but a 1.34-fold reduction in P450 activities and a 1.72-fold increase in the accumulation of prochloraz in the mycelia. Treatment with the P450 enzyme inhibitor significantly synergized with the prochloraz toxicity. The wild-type strain was highly resistant to pyraclostrobin and carbendazim; similarly, the sensitivity of the knockout mutant to pyraclostrobin and carbendazim also notably increased. There was no significant difference between the wild-type strain and the gene-complemented strain. The homology model and molecular docking analysis provide evidence that prochloraz interacts with the protein structure of CYP55A3. These findings suggest that the overexpression of the target gene LtCYP51 and the detoxification gene CYP55A3 were involved in the molecular mechanisms of resistance to prochloraz by L. theobromae.

Identification of common and specific cold resistance pathways from cold tolerant and non-cold tolerant mango varieties.

Mango has frequently encountered severe climate and environmental challenges such as low temperatures, seriously affecting the sustainable development of the industry. In the study, physiological measurements showed that the activities of superoxide dismutase (SOD) and peroxidase (POD) were found to be higher in Jinhuang (JH) mango plants than those of Tainong (TN) mango plants under cold stress, indicating cold tolerant (JH) and non-cold tolerant (TN) mango varieties were firstly determined. Subsequently, transcriptomics showed 8,337 and 7,996 differentially expressed genes (DEGs) were respectively identified in JH and TN mango varieties treated at 4 °C for 36 h, while more DEGs (10,683 and 10,723) were screened when treated at 4 °C for 72 h. Quantitative real-time PCR (qRT-PCR) of the selected DEGs confirmed their transcriptional levels displayed agreement to the transcriptome data. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed two primary cold resistant regulation pathways, photosynthesis-antenna proteins pathway and photosynthesis pathway, were both significant annotated in the two mango varieties, indicating share the common regulation mechanism response to cold stress. However, five specific cold resistant pathways, such as amino acid and carbohydrate metabolisms, were identified in JH mango variety with cold stress for longer duration, indicating the specific regulation pathways in the cold tolerant mango varieties. Furthermore, 43 ethylene-responsive transcription factors (ERFs) were significantly annotated in JH mango after cold-treated for 72 h comparing with the control group, and three of them ERF109-1, ERF017-1 and ERF017-2 were highly expressed, which may play important regulatory roles in plant cold resistance. These results provided insights into the primary and specific molecular mechanisms of different mango varieties resistance to chill.

Exploring the molecular mechanisms of rice blast resistance and advances in breeding for disease tolerance.

Rice blast, caused by the fungus Magnaporthe oryzae (syn. Pyricularia oryzae), is a major problem in rice cultivation and ranks among the most severe fungal diseases. Cloning and identifying resistance genes in rice, coupled with a comprehensive examination of the interaction between M. oryzae and rice, may provide insights into the mechanisms of rice disease resistance and facilitate the creation of new rice varieties with improved germplasm. These efforts are essential for protecting food security. This review examines the discovery of genes that confer resistance or susceptiblity to M. oryzae in rice over the last decade. It also discusses how knowledge of molecular mechanisms has been used in rice breeding and outlines key strategies for creating rice varieties resistant to this disease. The strategies discussed include gene pyramiding, molecular design breeding, editing susceptibility genes, and increasing expression of resistance genes through pathogen challenge. We address the prospects and challenges in breeding for rice blast resistance, emphasizing the need to fully exploit germplasm resources, employ cutting-edge methods to identify new resistance genes, and develop innovative breeding cultivars. Additionally, we underscore the importance of understanding the molecular basis of rice blast resistance and developing novel cultivars with broad-spectrum disease resistance.

SnRNA-seq of adipose tissues reveals the potential cellular and molecular mechanisms of cold and disease resistance in Mongolian cattle

BackgroundMongolian cattle are local breeds in northern China with excellent adaptability to harsh environmental conditions. Adipose tissues play essential roles in tolerance to cold and disease, but the associated cellular and molecular mechanisms are unclear.MethodsSingle-nucleus RNA sequencing (snRNA-seq) was performed on the adipose tissues from the subcutaneous (SAT), greater omentum (OAT) and perirenal (PAT) of 3 healthy cattle. The adipogenic trajectory was analyzed, and the functional roles of gene of interest were verified in vitro.ResultsThere were different cell subpopulations in adipose tissues. The lipid-deposition adipocytes identified by the PTGER3 marker exhibited outstanding characteristics in SAT. In PAT and OAT, aldosterone was expressed to provide clues for the differential brown adipocytes. Among the DEGs by comparing OAT with SAT and PAT with OAT, C3 was significantly expressed in most of the cell populations in SAT. G0S2, LIPE, LPIN1, PTGER3 and RGCC took part in the adipogenic trajectory from preadipocyte commitment to mature adipocytes. S100A4 expression affected Ca2+ signaling and the expression of UCP1 ~ 3, FABP4 and PTGER3.ConclusionThe cell heterogeneity and genes expressed in adipose tissues of Mongolian cattle not only determine the endocrine and energy storage, but contribute to adapt to cold and disease resistance.

An Isoflavone Synthase Gene in Arachis hypogea Responds to Phoma arachidicola Infection Causing Web Blotch.

Peanut web blotch is an important leaf disease caused by Phoma arachidicola, which seriously affects the quality and yield of peanuts. However, the molecular mechanisms of peanut resistance to peanut web blotch are not well understood. In this study, a transcriptome analysis of the interaction between peanut (Arachis hypogaea) and P. arachidicola revealed that total 2989 (779 up- and 2210 down-regulated) genes were all differentially expressed in peanut leaves infected by P. arachidicola at 7, 14, 21 days post inoculation. The pathways that were strongly differentially expressed were the flavone or isoflavone biosynthesis pathways. In addition, two 2-hydroxy isoflavanone synthase genes, IFS1 and IFS2, were strongly induced by P. arachidicola infection. Overexpression of the two genes enhanced resistance to Phytophthora parasitica in Nicotiana benthamiana. Knockout of AhIFS genes in peanut reduced disease resistance to P. arachidicola. These findings demonstrated that AhIFS genes play key roles in peanut resistance to P. arachidicola infection. Promoter analysis of the two AhIFS genes showed several defense-related cis-elements distributed in the promoter region. This study improves our understanding of the molecular mechanisms behind resistance of peanut infection by P. arachidicola, and provides important information that could be used to undertake greater detailed characterization of web blotch resistance genes in peanut.

Cloning and Identification of Common Carp (Cyprinus carpio) PI3KC3 and Its Expression in Response to CyHV-3 Infection.

Phosphoinositide 3-kinases (PI3Ks) are a class of key regulatory factors in eukaryotes that can inhibit viral replication by influencing autophagy. Currently, cyprinid herpesvirus 3 (CyHV-3) poses a serious threat to common carp culture. However, PI3K has not yet been identified in common carp. In this study, full-length PI3KC3 from common carp (CcPI3KC3), consisting of an open reading frame (ORF) of 2664 bp encoding a polypeptide of 887 amino acids, with a predicted molecular mass of 101.19 kDa and a theoretical isoelectric point (pI) of 5.97, was cloned. The amino acid and nucleotide sequences of CcPI3KC3 displayed high similarity to yellow catfish's (Tachysurus fulvidraco) PI3KC3. The tissue expression profile revealed that the mRNA levels of CcPI3KC3 in the liver, spleen, and head kidney were significantly greater than those in the brain, heart, intestines, gills, eyes, testes, and ovaries of common carp. We compared the expression patterns of CcPI3KC3 between "Longke-11" mirror carp (CyHV-3-resistant carp) and German mirror carp (non-resistant to CyHV-3) at different times (0, 48, 96, 144 h, 192, 240, 288 h post-infection (hpi)) after CyHV-3 infection. The results revealed that CcPI3KC3 mRNA expression significantly increased in the early infection stage. In the CyHV-3-resistant mirror carp variety, the relative expression of CcPI3KC3 was significantly greater at 48, 96, and 144 hpi compared with the nonbreeding strain groups after infection (p < 0.001). These results indicate that the full-length CcPI3KC3 sequence was successfully cloned from common carp for the first time, and it might play an important role in the immune system of common carp against CyHV-3 infection. This study provides a theoretical basis for the molecular mechanism of CyHV-3 resistance.

Molecular mechanisms of resistance and new therapeutic approaches in the treatment of colorectal cancer - a review of the literature

CRC occupies one of the leading positions among gastrointestinal malignancies and is a significant problem in Europe since it is the third most frequently diagnosed cancer. Recent developments in diagnostic techniques have led to higher chances of early diagnosis and survival; nevertheless, CRC is highly likely to relapse in the survivorably younger individuals. The importance of the current chemotherapy treatment and potential key therapeutic targets are identified in this review so that the molecular alterations causing drug resistance in CRC can be studied.Current literature formed the basis of this review by reviewing the molecular processes that underlie CRC, with emphasis on the mutational alterations in genes such as SENP1, KRAS, APC, TP53, and BRAF that play critical roles in CRC and resistance to treatment. Chemotherapy for CRC, targeting therapies, and immuno therapies have been discussed particularly with reference to their effectiveness for treatment and overcoming resistance.Genomic alterations in some important genes are involved in the onset of CRC and also determined the response to therapies. The KRAS mutations are associated with the resistance to EGFR inhibitors; however, BRAF mutations require BRAF/MEK inhibitors. Lack of MMR system SSR as a trigger for MSI-H status suggests a better response to immunotherapies. In addition, new molecules including SENP1, which involved the DNA repair pathway, and combination using CDK4/6 inhibitors are currently under development to overcome resistance and enhance the patients’ benefits.Colorectal cancer is still a problem, primarily because of its genetic character and high rates of recurrence. Even though chemotherapy and targeted therapies offer helpful results, the problem of resistance stands in the way. Subsequent studies should aim at symptomatic treatment outcomes and combine different drugs in order to enhance long-term treatment outcomes.

Different Doxorubicin Sensitivity Across Various Human Cancer Cell Lines

Doxorubicin (Dox) is a highly potent chemotherapeutic agent, approved by FDA since 1974, for treating a broad spectrum of cancers. However, development of severe side effects and drug resistance are main issues that limit the clinical use of Dox. Herein, we aimed to investigate the sensitivity of Dox in a variety of human cancer cell lines. Eleven cell lines were tested in this study including 2 hepatocellular carcinoma (HCC) cell lines (HepG2 and Huh7), 4 bladder cancer (BlCa) cell lines (UMUC-3, VMCUB-1, TCCSUP and BFTC-905), a lung cancer cell line (A549), a cervical carcinoma cell line (HeLa), a breast cancer cell line (MCF-7), a skin melanoma cell line (M21) and a noncancer human kidney cell line (HK-2). The MTT assay was employed for the determination of cytotoxicity. Cells were treated with various concentrations of Dox for 24 h. The half-maximal inhibitory concentration (IC50) of Dox was calculated to compare the Dox sensitivity among tested cell lines. The result showed that IC50 of Dox in HepG2, Huh7, UMUC-3, VMCUB-1, TCCSUP, BFTC-905, A549, HeLa, MCF-7, M21 and HK-2 cells were 12.2, &gt; 20, 5.1, &gt; 20, 12.6, 2.3, &gt; 20, 2.9, 2.5, 2.8 and &gt; 20 mM, respectively. BFTC-905 had the lowest IC50 value, therefore, it was the most sensitive to Dox. In contrast, Huh7, VMCUB-1 and A549 cells were resistant to Dox with IC50 values &gt; 20 mM. Conclusions, we demonstrated that different human malignant cell lines had different sensitivity to Dox. BFTC-905 BlCa cell line had the highest sensitivity to Dox. Huh7, VMCUB-1 and A549 cell lines were resistant to Dox. Perhaps, the different Dox sensitivity in different cell lines was due to the different acquisition of Dox resistance mechanisms. Huh7, VMCUB-1 and A549 cell lines could be suitable cell models to investigate the molecular mechanism of Dox resistance in different cancers. HIGHLIGHTS Different types of cancer cell lines exhibited different sensitivity to doxorubicin. BFTC-905, MCF-7 and M21 cell lines were sensitive to doxorubicin. HepG2, UMUC-3, TCCSUP and HeLa cells were moderately sensitive to doxorubicin. Huh7, VMCUB-1, A549 and HK-2 cells were resistant to doxorubicin. Huh7, VMCUB-1 and A549 cell lines could be suitable cell models for investigating the molecular pathways of Dox resistance in different types of cancers. GRAPHICAL ABSTRACT

MicroRNA-34a negatively regulates Netrin1 and mediates MEK/ERK pathway to regulate chemosensitivity of gastric cancer cells.

To explore the mechanism of action of MicroRNAs-34a (miR-34a) and Eurite growth guiding factor 1 (Netrin1) in cisplatin resistance in gastric cancer (GC), providing new clues for overcoming tumor resistance and optimizing anti-tumor therapy for GC. The Cancer Genome Atlas (TCGA), Differentially Expressed MicroRNAs (miRNAs) in human cancers (dbDEMC), and Starbase online databases were used to analyze the correlation between miR-34a and Netrin-1 and prognosis in GC, and to predict and verify the targeted binding of miR-34a to Netrin-1. The experimental methods including Cell transfection, real-time polymerase chain reaction (RT-PCR), Cell-Counting-Kit-8 (CCK8) assay, flow cytometry, wound scratch assay, transwell assay, and western blotting were used to investigate the effects of miR-34a and Netrin1 on chemotherapy resistance and biological characteristics in cisplatin-resistant GC cells (HGC27/DDP), and to analyze the molecular mechanism of cisplatin resistance. miR-34a expression was downregulated in gastric cancer clinical samples and cisplatin-resistant cells, while Netrin1 was upregulated, and was related to overall survival (OS). Upregulation of miR-34a can significantly reduce the IC50 value of cisplatin(0.65 vs 1.6 ng/mL) and Multidrug Resistance 1 (MDR-1) protein level, inhibit the proliferation activity, reduce the expression levels of proliferating cell nuclear antigen (PCNA) and ki-67 protein, and induce the increase of apoptosis rate and the enhancement of cycle arrest. Upregulation of miR-34a can also significantly reduce the expression level of Matrix metalloproteinase 9 (MMP9) protein, promote the expression of E-cadherin protein, reduce the wound healing rate and invasion number to inhibit migration and invasion ability in drug-resistant gastric cancer cells. Moreover, overexpression of Netrin1 on the basis of upregulation of miR-34a can weaken the above changes caused by upregulation of miR-34a. In addition, upregulation of miR-34a can significantly inhibit the Mitogen-activated protein kinase kinase (MEK) / Extracellular regulated protein kinases (ERK) pathway, while overexpression of Netrin1 can activate the MEK/ERK pathway, and inhibition of MEK/ERK pathway can effectively counteract the protein expression of Netrin1, and reverse changes in the expression of cisplatin IC50 and MDR-1 proteins caused by co-upregulation of miR-34a/Netrin1 in HGC27/DDP, as well as changes in proliferation, apoptosis, migration and invasion. In addition, upregulation of miR-34a can significantly inhibit the MEK/ERK pathway, while overexpression of Netrin1 can activate the MEK/ERK pathway. If the MEK/ERK pathway was inhibited, it can effectively counteract the protein overexpression of Netrin1, and reverse the changes in the expression of cisplatin IC50 and MDR-1 proteins in HGC27/DDP induced by co-upregulation of miR-34a / Netrin1, as well as changes in proliferation, apoptosis, migration and invasion. miR-34a targets and negatively regulates Netrin1 to mediate the proliferation, apoptosis, apoptosis, migration, and invasion of drug-resistant gastric cancer cells via the MEK/ERK pathway, and change the chemosensitivity in GC cells. miR-34a/Netrin1/MEK/ERK axis may serve as a novel therapeutic target for chemoresistance in GC, it is of great significance for overcoming drug resistance and developing new therapeutic strategies for GC.

Chromatin accessibility is associated with therapeutic response in prostate cancer.

Treatment of advanced prostate cancer is challenging due to a lack of effective therapies. Therefore, it is important to understand the molecular mechanisms underlying therapeutic resistance in prostate cancer and to identify promising drug targets offering significant clinical advantages. Given the pivotal role of dysregulated transcriptional programs in the therapeutic response, it is essential to prioritize translational efforts targeting cancer-associated transcription factors (TFs). The present study investigated whether chromatin accessibility was associated with therapeutic resistance in prostate cancer using Assay for Transposase-Accessible Chromatin with sequencing (ATAC-seq) data. The bioinformatics analysis identified differences in chromatin accessibility between the drug response (Remission) and drug resistance (Disease) groups. Additionally, a significant association was observed between chromatin accessibility, transcriptional output and TF activity. Among TFs, forkhead box protein M1 (FOXM1) was identified as a TF with high activity and expression in the Disease group. Notably, the results of the computational analysis were validated by FOXM1 knockdown experiments, which resulted in suppressed cell proliferation and enhanced therapeutic sensitivity in prostate cancer cells. The present findings demonstrated that chromatin accessibility and TF activity may be associated with therapeutic resistance in prostate cancer. Additionally, these results provide the basis for future investigations aimed at understanding the molecular mechanisms of drug resistance and developing novel therapeutic approaches for prostate cancer.

Molecular mechanisms of heterosis under drought stress in maize hybrids Zhengdan7137 and Zhengdan7153.

Maize is one of the most successful crops in utilizing heterosis which significantly improves maize stresses resistance and yield. Drought is a destructive abiotic stress that significantly reduces crop yield, particularly in maize. Drought stress and re-watering frequently occur during the growth and development of maize; however, the molecular mechanisms of heterosis under drought stress and re-watering have rarely been systematically investigated. Zhengdan7137 and Zhengdan7153 are two maize hybrid varieties with robust heterosis, and separately belongs to the SS×NSS and Reid×Tangsipingtou heterotic groups. 54 transcriptomes of these two hybrids and their parental inbred lines were analyzed under well-watering (WW), water-deficit (WD), and re-watering (RW) conditions using RNA-Seq. In this study, we identified 3,411 conserved drought response genes (CDRGs) and 3,133 conserved re-watering response genes (CRRGs) between Zhengdan7137 and Zhengdan7153. When comparing CDRGs and CRRGs to overdominance and underdominance genes, we identified 303 and 252 conservative drought response overdominance genes (DODGs) and underdominance genes (DUDGs), respectively, and 165 and 267 conservative re-watering response overdominance genes (RODGs) and underdominance genes (RUDGs), respectively. DODGs are involved in stress response-related processes, such as L-phenylalanine metabolism, carbohydrate metabolism, and heat response, whereas DUDGs are associated with glucose metabolism, pentose-phosphate shunt, and starch metabolism. RODGs and RUDGs contribute to the recovery of hybrids from drought stress by upregulating cell propagation and photosynthesis processes, and repressing stress response processes, respectively. It indicated overdominant and underdominant genes conservatively contributed to hybrid heterosis under drought stress. These results deepen our understanding of the molecular mechanisms of drought resistance, uncover conservative molecular mechanisms of heterosis under drought stress and re-watering, and provide potential targets for improving drought resistance in maize.