Minichromosome Maintenance Protein Research Articles

Systematic analysis of expression and prognostic significance for MCM family in head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSC) is a common malignant tumor in the world and has a poor prognosis. The family of minichromosome maintenance proteins (MCM) improves the stability of genome replication by inhibiting the rate of DNA replication in eukaryotic cells, thus, small changes in physiological MCM levels would increase the instability of gene replication and increase the incidence of tumor formation, most of which are significantly elevated in multiple cancers. However, the expression of different MCM families in HNSC and their prognostic value remain unclear. ONCOMINE and GEPIA databases were used to analyze the expression of MCMs in HNSC. The Kaplan-Meier plotter database was used to identify molecules with prognostic values. We collected 77 HNSC tissues and 50 normal tissues to validate the results of the bioinformatics analysis by immunohistochemical staining. The expression of MCM3, MCM5 and MCM6 in mRNA and protein levels were higher in HNSC. Moreover, the increased expression of MCM3, MCM5 and MCM6 in mRNA and protein levels predicted better prognosis of HNSC patients. Furthermore, multivariate analysis showed that high expressions of MCM3, MCM5 and MCM6 in protein level may be independent prognostic factors for HNSC patients. The results of this study indicated that MCM3, MCM5 and MCM6 play an important role in occurrence and development in HNSC and might be risk factors for the survival of HNSC patients.

Unwinding Helicase MCM Functionality for Diagnosis and Therapeutics of Replication Abnormalities Associated with Cancer: A Review.

The minichromosome maintenance (MCM) protein is a component of an active helicase that is essential for the initiation of DNA replication. Dysregulation of MCM functions contribute to abnormal cell proliferation and genomic instability. The interactions of MCM with cellular factors, including Cdc45 and GINS, determine the formation of active helicase and functioning of helicase. The functioning of MCM determines the fate of DNA replication and, thus, genomic integrity. This complex is upregulated in precancerous cells and can act as an important tool for diagnostic applications. The MCM protein complex can be an important broad-spectrum therapeutic target in various cancers. Investigations have supported the potential and applications of MCM in cancer diagnosis and its therapeutics. In this article, we discuss the physiological roles of MCM and its associated factors in DNA replication and cancer pathogenesis.

Abstract 6988: TP53RK regulates DNA replication by CDC7-mediated MCM helicase phosphorylation in colorectal cancer

Abstract Background: We identify TP53 regulating kinase (TP53RK), which showed the highest cell growth inhibition efficiency in six colon cancer cell lines. TP53RK is overexpressed in various cancer types, including multiple myeloma and skin cancer, but the mechanism for its tumorigenesis in colon cancer is unknown. Therefore, this study aims to reveal the tumorigenesis mechanism of TP53RK, which is overexpressed in Colorectal Cancer (CRC), through global and phospho-proteomics. Method: A total 5 CRC cell lines (HT29, SW480, HCT116, H508 and CaCO2), colon normal fibroblast CRL1459, HCT116 p53 null cell and patient-derived normal organoid were used. Immunoblotting, MTT assay, Colony formation assay, Annexin-V assay and cell cycle analysis were performed for evaluation of TP53RK loss-of-function. With kinase-substrate enrichment analysis with phospho-proteome analysis, MCM2 was found to be a substrate for the kinase regulated by TP53RK. Results: High-throughput genetic screening approach have been widely applied to the study the gene function and molecular mechanism associated with tumorigenesis. By using genome-wide CRISPR/Cas9 library screening, we identify TP53RK, the first committed negative-selected gene, as a tyrosine kinase in the colorectal cancer(CRC) specific biomarker. Through proteome analysis, we found that depletion of TP53RK can hypo-phosphorylate the DNA helicase complex, MCM2 (minichromosome maintenance protein2). According to previous studies, the phosphorylation of MCM2 is regulated by CDC7 (cell division cycle7), and the abnormal states of CDC7 and MCM2 cause DNA replication disorder. Our results show that TP53RK expression is upregulated in CRC and its depletion results in decreased CDC7 expression and hypo-phosphorylation of the MCM complex. Decreased CDC7 expression due to its instability after TP53RK depletion can lead to DNA replication errors. DNA replication errors can lead cancer cells to apoptosis, suggesting that they may be a strategy for cancer treatment. In summary, we provide TP53RK as a novel prognostic and therapeutic target in CRC. Conclusion: To recapitulate briefly, our findings suggest that the interaction of TP53RK with CDC7 can regulate CDC7 protein stability and stabilized CDC7 can phosphorylate MCM2 to initiate DNA replication. In other words, because overexpression of TP53RK acts as an oncogene that promotes tumor progression in CRC, depletion of TP53RK can degrade CDC7 and induce colon cancer cells to death or regression. Citation Format: Younghee Choi, Ji-won Park, Jun-kyu Kang, Eun-ju Kim, Sang-Hyun Song, Eugene C. Yi, Tae-You Kim. TP53RK regulates DNA replication by CDC7-mediated MCM helicase phosphorylation in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6988.

Role of Serine arginine protein kinase 1 and Minichromosome maintenance protein 2 in predicting epithelial ovarian cancer response to treatment and prognosis.

Serine-Arginine (SR) proteins are a conserved family of proteins involved in RNA splicing and are reported to be over-expressed in multiple cancers. The aim of the study is evaluation of the expression of Serine arginine protein kinase 1 (SRPK1) and Minichromosome maintenance protein 2 (MCM2) in epithelial ovarian cancer (EOC) and their correlation with clinicopathological features, response to therapy, progression-free survival (PFS), and cancer-specific survival (CSS). This study was carried out on surgical specimens of 65 patients diagnosed with EOC which were submitted to immunohistochemical staining by SRPK1 and MCM2 antibodies. About 89.2% of cases showed SRPK1 expression and its high expression was significantly associated with type II tumors and advanced stage. All cases showed nuclear immunoreaction for MCM2 with high expression in 49.2% of cases. There was a significant relationship between high values of SRPK1 H-score and percentage of MCM2. Postmenopause, type II pathology, advanced stage, absence of complete response to the treatment, resistance to platinum-based chemotherapy, and surgery done by a general surgeon were the factors affecting PFS. Response to treatment and platinum sensitivity were the most independent factors affecting patients' PFS. The factors associated with shorter CSS were suboptimal debulking, advanced stage, absence of complete response to the treatment, platinum resistance, and high SRPK1. High SRPK1 expression and platinum sensitivity were the independent factors affecting patients' CSS. SRPK1 is an unfavorable biomarker in EOC patients because of its association with aggressive histologic type, advanced International Federation of Gynecology and Obstetrics (FIGO) stage, and worse survival. SRPK1 could promote the proliferation of EOC by up-regulation of MCM2.

A critical threshold of MCM10 is required to maintain genome stability during differentiation of induced pluripotent stem cells into natural killer cells.

Natural killer (NK) cell deficiency (NKD) is a rare disease in which NK cell function is reduced, leaving affected individuals susceptible to repeated viral infections and cancer. Recently, a patient with NKD was identified carrying compound heterozygous variants of MCM10 (minichromosome maintenance protein 10), an essential gene required for DNA replication, that caused a significant decrease in the amount of functional MCM10. NKD in this patient presented as loss of functionally mature late-stage NK cells. To understand how MCM10 deficiency affects NK cell development, we generated MCM10 heterozygous (MCM10+/-) induced pluripotent stem cell (iPSC) lines. Analyses of these cell lines demonstrated that MCM10 was haploinsufficient, similar to results in other human cell lines. Reduced levels of MCM10 in mutant iPSCs was associated with impaired clonogenic survival and increased genomic instability, including micronuclei formation and telomere erosion. The severity of these phenotypes correlated with the extent of MCM10 depletion. Significantly, MCM10+/- iPSCs displayed defects in NK cell differentiation, exhibiting reduced yields of hematopoietic stem cells (HSCs). Although MCM10+/- HSCs were able to give rise to lymphoid progenitors, these did not generate mature NK cells. The lack of mature NK cells coincided with telomere erosion, suggesting that NKD caused by these MCM10 variants arose from the accumulation of genomic instability including degradation of chromosome ends.

Effects of geniposide on innate immunity and antiviral activity of Scyllaparamamosain

In this study, we examined the impact of geniposide on the innate immunity of the mud crab Scylla paramamosain, specifically in relation to WSSV infection. Through the use of in vitro cell culture experiments, we assessed the effects of geniposide on various parameters of hemocyte activity in S. paramamosain. Our findings revealed that high doses of geniposide inhibited hemocyte growth, with an optimal dose of 100 mg/kg determined. Additionally, we observed that geniposide increased the total hemocyte counts in S. paramamosain following WSSV infection. Geniposide also enhanced the enzymatic activities in hemolymph following treatment. The enzymes affected by geniposide encompassed ACP (acid phosphatase), POD (phenol oxidase catalase), PO (phenoloxidase), SOD (superoxide dismutase), CAT (catalase), and LZM (lysozyme). Furthermore, the activities of ACP, POD, PO, and LZM were also observed to increase subsequent to infection with WSSV. Notably, geniposide was found to enhance the phagocytosis of V. alginolyticus within the hemocytes. Geniposide can reduce hemocyte apoptosis rates after treatment, as well as hemocytes infected with WSSV. Furthermore, geniposide treatment significantly up-regulated the expression level of Myosin, but expression levels of Astakine, C-type lectin (CTL), STAT, JAK, proPO, minichromosome maintenance protein (MCM7), caspase-3 and crustin were down-regulated in the hemocytes. Additionally, geniposide treatment inhibited WSSV replication in hemocytes of S. paramamosain, and enhanced the survival rates of mud crabs following WSSV infection. These experimental results provide evidence that geniposide can improve the immune response by regulating humoral immunity and cellular immunity, and enhance pathogen resistance in S. paramamosain.

RIF1 regulates early replication timing in murine B cells

The mammalian DNA replication timing (RT) program is crucial for the proper functioning and integrity of the genome. The best-known mechanism for controlling RT is the suppression of late origins of replication in heterochromatin by RIF1. Here, we report that in antigen-activated, hypermutating murine B lymphocytes, RIF1 binds predominantly to early-replicating active chromatin and promotes early replication, but plays a minor role in regulating replication origin activity, gene expression and genome organization in B cells. Furthermore, we find that RIF1 functions in a complementary and non-epistatic manner with minichromosome maintenance (MCM) proteins to establish early RT signatures genome-wide and, specifically, to ensure the early replication of highly transcribed genes. These findings reveal additional layers of regulation within the B cell RT program, driven by the coordinated activity of RIF1 and MCM proteins.

A First-in-Human, Phase 1, Dose Escalation Study of Sgr-2921 As Monotherapy in Subjects with Relapsed/Refractory Acute Myeloid Leukemia or Myelodysplastic Syndrome

Background Cell division cycle 7-related protein kinase (CDC7), or DBF4-dependent CDC7 kinase (DDK), is a cell cycle kinase that maintains DNA replication by phosphorylation and activation of the minichromosome maintenance protein 2 and 4 (MCMs), components of the replicative DNA helicase. Due to the central role of CDC7 in maintenance of the replication fork integrity, chemical inhibition of CDC7 kinase can ultimately lead to cancer cell death. SGR-2921 is an oral, small molecule inhibitor of CDC7. Preclinical studies demonstrate that, among all cell lines tested, SGR-2921 has the most potent anti-proliferative activity in AML. Potent antitumor activity has also been demonstrated in cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) AML models. This antitumor response is observed in animal models representative of difficult to treat patient populations and appears to be agnostic of serious mutations (including those with p53 mutations and FLT3 mutations), BTK resistance, and multiple prior lines of treatment. Patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) or high-risk (HR) or very high-risk (VHR) myelodysplastic syndrome (MDS) have low response rates and poor overall survival. Considering the potent preclinical activity of SGR-2921 in AML and MDS models, coupled with the high unmet medical need in this population, SGR-2921 is being evaluated in patients with R/R AML and HR/VHR MDS. Study Design and Methods This is a phase 1, FIH, open-label, single-agent, two-arm, dose escalation study (NCT#05961839) designed to evaluate safety and tolerability and identify the recommended phase 2 dose (RP2D) of SGR-2921 as monotherapy in subjects with R/R AML, HR MDS, or VHR MDS. The study utilizes a hybrid accelerated titration design with single patient cohorts that transitions to a 3+3 design once a single Grade 2 event or DLT is observed. This is a multicenter global study (US, Spain and France) with an estimated study recruitment start date in October, 2023. SGR-2921 will be administered orally, once daily, utilizing a 5-day on and 9-day off dosing schedule over a 28-day cycle. Up to a maximum of 144 patients will be enrolled in the dose escalation and exploratory cohort phase of the study. To evaluate the effect of CYP3A4 inhibition on SGR-2921 exposure, subjects will be enrolled into one of two staggered, parallel study treatment arms, according to concomitant administration with (Arm B) or without (Arm A) azole antifungals that are strong CYP3A4 inhibitors at time of first dose. Safety and tolerability must be demonstrated in treatment Arm A, at the first two dose levels before initiating treatment Arm B. A single dose PK run-in will be required for subjects enrolled into the first 3 cohorts of each treatment arm. Subjects will be treated at increasing doses of study drug until all dose levels have been investigated or any dose level is found to exceed the maximum tolerated dose (MTD). A RP2D will be selected from one of the tolerable dose levels which will not exceed the MTD (see Figure 1 for study design). Key study inclusion criteria include: Age ≥ 18 years of age; Life expectancy ≥ 8 weeks; Confirmed diagnosis of R/R AML or HR and VHR MDS; Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2. Key study exclusion criteria include: Active malignancies not related to AML or MDS within two years prior to the first dose or requiring ongoing treatment; Clinical evidence of central nervous system (CNS) or pulmonary leukostasis; ≥ Grade 3 disseminated intravascular coagulation, or active CNS leukemia; QT interval corrected for heart rate per Fridericia's formula ≥470 msec during screening ECG. The study primary objectives are to evaluate the safety and tolerability of SGR-2921 as monotherapy and identify RP2D including MTD. Secondary objectives include evaluating the pharmacokinetics (PK) of SGR-2921 and investigating preliminary antitumor activity (composite complete remission rate, objective response rate, duration of response, etc.).

Quantitative Proteomic Analysis Deciphers the Molecular Mechanism for Endosperm Nuclear Division in Early Rice Seed Development.

Understanding the molecular mechanisms underlying early seed development is important in improving the grain yield and quality of crop plants. We performed a comparative label-free quantitative proteomic analysis of developing rice seeds for the WT and osctps1-2 mutant, encoding a cytidine triphosphate synthase previously reported as the endospermless 2 (enl2) mutant in rice, harvested at 0 and 1 d after pollination (DAP) to understand the molecular mechanism of early seed development. In total, 5231 proteins were identified, of which 902 changed in abundance between 0 and 1 DAP seeds. Proteins that preferentially accumulated at 1 DAP were involved in DNA replication and pyrimidine biosynthetic pathways. Notably, an increased abundance of OsCTPS1 was observed at 1 DAP; however, no such changes were observed at the transcriptional level. We further observed that the inhibition of phosphorylation increased the stability of this protein. Furthermore, in osctps1-2, minichromosome maintenance (MCM) proteins were significantly reduced compared with those in the WT at 1 DAP, and mutations in OsMCM5 caused defects in seed development. These results highlight the molecular mechanisms underlying early seed development in rice at the post-transcriptional level.

Neighboring inteins interfere with one another's homing capacity.

Inteins are mobile genetic elements that invade conserved genes across all domains of life and viruses. In some instances, a single gene will have several intein insertion sites. In Haloarchaea, the minichromosome maintenance (MCM) protein at the core of replicative DNA helicase contains four intein insertion sites within close proximity, where two of these sites (MCM-a and MCM-d) are more likely to be invaded. A haloarchaeon that harbors both MCM-a and MCM-d inteins, Haloferax mediterranei, was studied in vivo to determine intein invasion dynamics and the interactions between neighboring inteins. Additionally, invasion frequencies and the conservation of insertion site sequences in 129 Haloferacales mcm homologs were analyzed to assess intein distribution across the order. We show that the inteins at MCM-a and MCM-d recognize and cleave their respective target sites and, in the event that only one empty intein invasion site is present, readily initiate homing (i.e. single homing). However, when two inteins are present co-homing into an intein-free target sequence is much less effective. The two inteins are more effective when invading alleles that already contain an intein at one of the two sites. Our in vivo and computational studies also support that having a proline in place of a serine as the first C-terminal extein residue of the MCM-d insertion site prevents successful intein splicing, but does not stop recognition of the insertion site by the intein's homing endonuclease.

MCM4 acts as a biomarker for LUAD prognosis.

MCM4 forms the pre-replication complex (MCM2-7) with five other minichromosome maintenance (MCM) proteins. This complex binds to replication origins at G1 stage in cell cycle process, playing a critical role in DNA replication initiation. Recently, MCM4 is reported to have a complex interaction with multiple cancer progression, including gastric, ovarian and cervical cancer. Here, this study mainly focused on the expression of MCM4 and its values in lung adenocarcinoma (LUAD). MCM4 was highly expressed in LUAD tumours and cells, and had an important effect on the overall survival. Overexpression of MCM4 promoted the proliferation, and suppressed the apoptosis in LUAD cells. However, MCM4 silence led to the opposite results. In vivo, knockdown of MCM4 inhibited tumour volume and weight in xenograft mouse model. As a member of DNA helicase, knockdown of MCM4 caused cell cycle arrest at G1 stage through inducing the expression of P21, a CDK inhibitor. These findings indicate that MCM4 may be a possible new therapeutic target for LUAD in the future.

Phylogeny and species delimitations in the economically, medically, and ecologically important genus Samsoniella (Cordycipitaceae, Hypocreales).

Samsoniella is a ubiquitous genus of cosmopolitan arthropod-pathogenic fungi in the family Cordycipitaceae. The fungi have economic, medicinal, and ecological importance. Prior taxonomic studies of these fungi relied predominantly on phylogenetic inferences from five loci, namely, the nuclear ribosomal small and large subunits (nr SSU and nr LSU), the 3' portion of translation elongation factor 1 alpha (3P_TEF), and RNA polymerase II subunits 1 and 2 (RPB1 and RPB2). Despite many new species being described, not all of the recognized species inside this group formed well-supported clades. Thus, the search for new markers appropriate for molecular phylogenetic analysis of Samsoniella remains a challenging problem. In our study, we selected the internal transcribed spacer regions of the rDNA (ITS rDNA) and seven gene regions, namely, 3P_TEF, the 5' portion of translation elongation factor 1 alpha (5P_TEF), RPB1, RPB2, γ-actin (ACT), β-tubulin (TUB), and a gene encoding a minichromosome maintenance protein (MCM7), as candidate markers for species identification. Genetic divergence comparisons showed that the ITS, RPB2, ACT, and TUB sequences provided little valuable information with which to separate Samsoniella spp. In contrast, sequence data for 3P_TEF, 5P_TEF, RPB1, and MCM7 provided good resolution of Samsoniella species. The phylogenetic tree inferred from combined data (5P_TEF + 3P_TEF + RPB1 + MCM7) showed well-supported clades for Samsoniella and allowed for the delimitation of 26 species in this genus. The other two species (S.formicae and S.lepidopterorum) were not evaluated, as they had abundant missing data.

Genome-wide binding sites of Plasmodium falciparum mini chromosome maintenance protein MCM6 show new insights into parasite DNA replication.

Multiple rounds of DNA replication take place in various stages of the life cycle in the human malaria parasite Plasmodium falciparum. Previous bioinformatics analysis has shown the presence of putative Autonomously Replicating Sequence (ARS) like sequences in the Plasmodium genome. However, the actual sites and frequency of replication origins in the P. falciparum genome based on experimental data still remain elusive. Minichromosome maintenance (MCM) proteins are recruited by the Origin recognition complex (ORC) to the origins of replication in eukaryotes including P. falciparum. We used PfMCM6 for chromatin immunoprecipitation followed by sequencing (ChIP-seq) in the quest for identification of putative replication origins in the parasite. PfMCM6 DNA binding sites annotation revealed high enrichment at exon regions. This is contrary to higher eukaryotes that show an inclination of origin sites towards transcriptional start sites. ChIP-seq results were further validated by ChIP-qPCR results as well as nascent strand abundance assay at the selected PfMCM6 enriched sites that also showed preferential binding of PfORC1 suggesting potential of these sites as origin sites. Further, PfMCM6 ChIP-seq data showed a positive correlation with previously published histone H4K8Ac genome-wide binding sites but not with H3K9Ac sites suggesting epigenetic control of replication initiation sites in the parasites. Overall, our data show the genome-wide distribution of PfMCM6 binding sites with their potential as replication origins in this deadly human pathogen that not only broadens our knowledge of parasite DNA replication and its unique biology, it may help to find new avenues for intervention processes.

Pan-Cancer Multi-Omics Analysis of Minichromosome Maintenance Proteins (MCMs) Expression in Human Cancers.

Epigenetic modifications, such as transcription, DNA repair, and replication significantly influence tumour development. Aberrant gene expression and modifications can have a crucial impact on the initiation and progression of tumours. The minichromosome maintenance (MCM) protein family, which is responsible for DNA synthesis, plays a crucial role in tumorigenesis and chemotherapy resistance by regulating the cell cycle and DNA replication stress. Recent studies have shown that dysregulation of the MCMs can lead to these negative outcomes. This study aimed to examine the role of the MCM proteins in DNA synthesis in 33 types of cancers. Various public databases were used to examine the expression, methylation regulation, mutations, and functions of eight MCM proteins (MCM2-9) in pan-cancer. The study investigated the correlation between abnormal MCM expression and clinical outcomes, including prognosis and drug response. The microRNA-mRNA network upstream of the MCM genes and the downstream signalling pathways were extensively investigated to determine the molecular mechanisms that drive tumour development. The study found that the MCM gene expressions differed depending on the type of cancer; high MCM gene expression was linked to poor overall survival in most cancers. Additionally, MCM gene expression was associated with various immunological features and drug sensitivity. These findings offer important insights for the development of targeted cancer therapies. Altogether, this study reveals that the MCM genes are differentially expressed across various cancers and are associated with clinical prognoses. These genes may influence the occurrence and development of tumours through several pathways, including the PI3K-AKT, PAS/MAPK and TSC/mTOR signalling pathways and immune-related pathways.

Glutamine Regulates Gene Expression Profiles to Increase the Proliferation of Porcine Intestinal Epithelial Cells and the Expansion of Intestinal Stem Cells.

The intestinal epithelium is known for its rapid self-renewal, and glutamine is crucial in providing carbon and nitrogen for biosynthesis. However, understanding how glutamine affects gene expression in the intestinal epithelium is limited, and identifying the essential genes and signals involved in regulating intestinal epithelial cell growth is particularly challenging. In this study, glutamine supplementation exhibited a robust acceleration of intestinal epithelial cell proliferation and stem cell expansion. RNA sequencing indicated diverse transcriptome changes between the control and glutamine supplementation groups, identifying 925 up-regulated and 1152 down-regulated genes. The up-regulated DEGs were enriched in the KEGG pathway of cell cycle and GO terms of DNA replication initiation, regulation of phosphatidylinositol 3-kinase activity, DNA replication, minichromosome maintenance protein (MCM) complex, and ATP binding, whereas the down-regulated DEGs were enriched in the KEGG pathway of p53 signaling pathway, TNF signaling pathway, and JAK-STAT signaling pathway and GO terms of inflammatory response and intrinsic apoptotic signaling pathway in response to endoplasmic reticulum stress. Furthermore, GSEA analysis revealed a significant up-regulation of the cell cycle, DNA replication initiation, ATP-dependent RNA helicase activity, and down-regulation of the TNF signaling pathway. The protein-protein association network of the intersecting genes highlighted the significance of DNA replication licensing factors (MCM3, MCM6, and MCM10) in promoting intestinal epithelial growth in response to glutamine. Based on these findings, we propose that glutamine may upregulate DNA replication licensing factors, leading to increased PI3K/Akt signaling and the suppression of TNF, JAK-STAT, and p53 pathways. Consequently, this mechanism results in the proliferation of porcine intestinal epithelial cells and the expansion of intestinal stem cells.

MCM-2 Levels as a Potential Biomarker for Predicting High-Risk Breast Cancer Patients According to TAILORx Classification.

The minichromosome maintenance protein-2 (MCM-2) is a more sensitive proliferation marker than Ki-67. This study aimed to evaluate the relationship between MCM-2 and Oncotype DX recurrence score (ODX-RS) and determine an MCM-2 cutoff value in high-risk patients according to TAILORx risk categorization. Hormone receptor (HR) positive HER-2 negative early-stage breast cancer patients (pT1-2, pN0-N1, M0) who had ODX-RS were included in the study. According to the TAILORx trial, patients were divided into two groups with high (ODX-RS ≥26) and low risk (ODX-RS <26) in terms of ODX-RS. Formalin-fixed-paraffin-embedded tissues of patients were re-evaluated, and 3 µm sections were prepared for MCM-2 immuno-histochemical staining. The relationship between ODX-RS and the percentage of MCM-2 staining was evaluated in two groups. The ROC curve analysis was performed to determine the MCM-2 cut-off value for the TAILORx high-risk group (ODX-RS ≥26). The mean MCM-2 value was significantly higher in the high-risk group [(60.2 ± 11.2 vs 34.4 ± 13.8, p < 0.001)]. In the multivariate analysis, MCM-2 (OR: 1.27, 95% CI: 1.08-1.49, p = 0.003) and progesterone receptor (PR) levels ≤10% (OR: 60.9, 95% CI: 4.1-89.7, p = 0.003) were found to be independent factors indicating a high-risk group. A one-unit increase in MCM-2 level increased the likelihood of being in the high-risk group by 1.27 times. In the ROC curve analysis, the optimal MCM-2 cut-off level was 50 (AUC: 0.921, sensitivity: 86.7%, specificity: 96.0%, p < 0.001). Our study is the first study in the literature to investigate the relationship between ODX-RS and MCM-2 levels in HR-positive HER-2 negative early breast-cancer patients. In this study, MCM-2 was an independent risk factor in identifying high-risk patients according to TAILORx risk classification. MCM 2 cut-off value (50) may help the decision on adjuvant chemotherapy in patients where the Oncotype DX test cannot be performed.

New Resinogalea species from Araucaria araucana resin in Chile and reclassification of the genus in the Cryptocaliciomycetidae.

Araucaria araucana is an ancient conifer, native to the mountain ranges in Chile and Argentina. These trees host a large number of organisms, mainly insects, strongly or even exclusively associated with them. The recent emergence of a novel canker disease on A. araucana has emphasised the importance of fungi associated with these iconic trees and has resulted in the discovery of various new species. In this study, we considered the identity of an unknown calicioid fungus consistently found on resin on the branches of A. araucana. Preliminary phylogenetic analyses placed isolates in the recently described sub-class Cryptocaliciomycetidae, closest to Cryptocalicium blascoi. However, the morphology of the ascomata and its occurrence in a unique niche suggested that the closest relative could be Resinogalea humboldtensis (Bruceomycetaceae, incertae sedis), a fungus with similar sporing structures found on resin of Araucaria humboldtensis in New Caledonia. There are no living cultures or sequence data available for either R. humboldtensis or its supposed closest relative, Bruceomyces castoris, precluding sequence-based comparisons. Morphological comparisons of the sporing structures on A. araucana confirmed that the ascomatal morphology of our unknown calicioid fungus and R. humboldtensis are almost identical and resemble each other more so than B. castoris or Cr. blascoi. A phylogenetic analysis based on the small subunit (SSU), internal transcribed spacer (ITS) and large subunit (LSU) rDNA regions resolved our strains into two clades with Cr. blascoi as its closest relative. Further analyses applying the Genealogical Concordance Phylogenetic Species Recognition (GCPSR) based on ITS, mini chromosome maintenance protein complex (MCM7), RNA polymerase II second largest subunit (RPB2) and translation elongation factor 1-alpha (TEF) gene regions, confirmed that strains represent two new species. Based on our morphological observations and phylogenetic analyses, we introduce two new Resinogalea species, R. araucana and R. tapulicola, and reclassify the genus in the subclass Cryptocaliciomycetidae.

Minichromosome maintenance proteins in lung adenocarcinoma: Clinical significance and therapeutic targets.

Lung cancer is the most common cause of cancer-related death worldwide, accounting for 1.8 million deaths annually. Analysis of The Cancer Genome Atlas data showed that all members of the minichromosome maintenance (MCM) family (hexamers involved in DNA replication: MCM2-MCM7) were upregulated in lung adenocarcinoma (LUAD) tissues. High expression of MCM4 (P = 0.0032), MCM5 (P = 0.0032), and MCM7 (P = 0.0110) significantly predicted 5-year survival rates in patients with LUAD. Simurosertib (TAK-931) significantly suppressed the proliferation of LUAD cells by inhibiting cell division cycle 7-mediated MCM2 phosphorylation. This finding suggested that MCM2 might be a therapeutic target for LUAD. Moreover, analysis of the epigenetic regulation of MCM2 showed that miR-139-3p, miR-378a-5p, and miR-2110 modulated MCM2 expression in LUAD cells. In patients with LUAD, understanding the role of these miRNAs may improve prognoses.

Minichromosome maintenance protein family member 6 mediates hepatocellular carcinoma progression by recruiting UBE3A to induce P53 ubiquitination

With limited therapeutic options for hepatocellular carcinoma (HCC), it is of great significance to investigate the underlying mechanisms and identifying tumor drivers. MCM6, a member of minichromosome maintenance proteins (MCMs), was significantly elevated in HCC progression and associated with poor prognosis. Knockdown of MCM6 significantly inhibited the proliferation and migration of HCC cells with the increased apoptosis ratio and cell cycle arrest, whereas overexpression of MCM6 induced adverse effects. Mechanistically, MCM6 could decrease the P53 activity by inducing the degradation of P53 protein. In addition, MCM6 enhanced the ubiquitination of P53 by recruiting UBE3A to form a triple complex. Furthermore, overexpression of UBE3A significantly rescued the P53 activation and suppression of malignant behaviors mediated by MCM6 inhibition. In conclusion, MCM6 facilitated aggressive phenotypes of HCC cells by UBE3A/P53 signaling, providing potential biomarkers and targets for HCC.

Activity, substrate preferenceand structure of the HsMCM8/9 helicase.

The minichromosomal maintenance proteins, MCM8 and MCM9, are more recent evolutionary additions to the MCM family, only cooccurring in selected higher eukaryotes. Mutations in these genes are directly linked to ovarian insufficiency, infertility, and several cancers. MCM8/9 appears to have ancillary roles in fork progression and recombination of broken replication forks. However, the biochemical activity, specificitiesand structures have not been adequately illustrated, making mechanistic determination difficult. Here, we show that human MCM8/9 (HsMCM8/9) is an ATP dependent DNA helicase that unwinds fork DNA substrates with a 3'-5' polarity. High affinity ssDNA binding occurs in the presence of nucleoside triphosphates, while ATP hydrolysis weakens the interaction with DNA. The cryo-EM structure of theHsMCM8/9 heterohexamer was solved at 4.3 Å revealing a trimer of heterodimer configuration with two types of interfacial AAA+ nucleotide binding sites that become more organized upon binding ADP. Local refinements of the N or C-terminal domains (NTD or CTD) improved the resolution to 3.9 or 4.1 Å, respectively, and shows a large displacement in the CTD. Changes in AAA+ CTD upon nucleotide binding and a large swing between the NTD and CTD likely implies that MCM8/9 utilizes a sequential subunit translocation mechanism for DNA unwinding.