In silico functional, structural and pathogenicity analysis of missense single nucleotide polymorphisms in human MCM6 gene.

Single nucleotide polymorphisms (SNPs) are one of the most common determinants and potential biomarkers of human disease pathogenesis. SNPs could alter amino acid residues, leading to the loss of structural and functional integrity of the encoded protein. In humans, members of the minichromosome maintenance (MCM) family play a vital role in cell proliferation and have a significant impact on tumorigenesis. Among the MCM members, the molecular mechanism of how missense SNPs of minichromosome maintenance complex component 6 (MCM6) contribute to DNA replication and tumor pathogenesis is underexplored and needs to be elucidated. Hence, a series of sequence and structure-based computational tools were utilized to determine how mutations affect the corresponding MCM6 protein. From the dbSNP database, among 15,009 SNPs in the MCM6 gene, 642 missense SNPs (4.28%), 291 synonymous SNPs (1.94%), and 12,500 intron SNPs (83.28%) were observed. Out of the 642 missense SNPs, 33 were found to be deleterious during the SIFT analysis. Among these, 11 missense SNPs (I123S, R207C, R222C, L449F, V456M, D463G, H556Y, R602H, R633W, R658C, and P815T) were found as deleterious, probably damaging, affective and disease-associated. Then, I123S, R207C, R222C, V456M, D463G, R602H, R633W, and R658C missense SNPs were found to be highly harmful. Six missense SNPs (I123S, R207C, V456M, D463G, R602H, and R633W) had the potential to destabilize the corresponding protein as predicted by DynaMut2. Interestingly, five high-risk mutations (I123S, V456M, D463G, R602H, and R633W) were distributed in two domains (PF00493 and PF14551). During molecular dynamics simulations analysis, consistent fluctuation in RMSD and RMSF values, high Rg and hydrogen bonds in mutant proteins compared to wild-type revealed that these mutations might alter the protein structure and stability of the corresponding protein. Hence, the results from the analyses guide the exploration of the mechanism by which these missense SNPs of the MCM6 gene alter the structural integrity and functional properties of the protein, which could guide the identification of ways to minimize the harmful effects of these mutations in humans.

High MCM6 expression promotes proliferation and correlates with poor prognosis in triple-negative breast cancer.

OBJECTIVE: Triple-negative breast cancer (TNBC) is an aggressive subtype with a poor prognosis. Minichromosome maintenance genes (MCM2-7) crucial for DNA replication are significant biomarkers for various tumor types; however, their roles in TNBC remain underexplored. MATERIALS AND METHODS: We utilized four TNBC-related GEO databases to examine MCM2-7 gene expression and predict its prognosis in TNBC, performing single-cell analysis and GSEA to discover MCM6's potential function. The Cancer Dependency Map gene effect scores and CCK8 assay were used to assess MCM6's impact on TNBC cell proliferation. The correlations between MCM6 expression, immune infiltrates, and immune cells were also analyzed. WGCNA and LASSO Cox regression built a risk score model predicting TNBC patient survival based on MCM6-related gene expression. RESULTS: MCM2-7 gene expression was higher in TNBC tissues compared to adjacent normal tissues. High MCM6 expression correlated with shorter TNBC patient survival time. GSEA and single-cell analysis revealed a relationship between elevated MCM6 expression and the cell cycle pathway. MCM6 knockdown inhibited TNBC cell proliferation. A risk model featuring MCM6, CDC23, and CCNB1 effectively predicts TNBC patient survival. CONCLUSIONS: MCM6 overexpression in TNBC links to a worse prognosis and reduced cell proliferation upon MCM6 knockdown. We developed a risk score model based on MCM6-related genes predicting TNBC patient prognosis, potentially assisting future treatment strategies.

Multi-omics pan-cancer analyses identify MCM4 as a promising prognostic and diagnostic biomarker.

Minichromosome Maintenance Complex Component 4 (MCM4) is a vital component of the mini-chromosome maintenance complex family, crucial for initiating the replication of eukaryotic genomes. Recently, there has been a growing interest in investigating the significance of MCM4 in different types of cancer. Despite the existing research on this topic, a comprehensive analysis of MCM4 across various cancer types has been lacking. This study aims to bridge this knowledge gap by presenting a thorough pan-cancer analysis of MCM4, shedding light on its functional implications and potential clinical applications. The study utilized multi-omics samples from various databases. Bioinformatic tools were employed to explore the expression profiles, genetic alterations, phosphorylation states, immune cell infiltration patterns, immune subtypes, functional enrichment, disease prognosis, as well as the diagnostic potential of MCM4 and its responsiveness to drugs in a range of cancers. Our research demonstrates that MCM4 is closely associated with the oncogenesis, prognosis and diagnosis of various tumors and proposes that MCM4 may function as a potential biomarker in pan-cancer, providing a deeper understanding of its potential role in cancer development and treatment.

Hypoxia Induces Tumor-Derived Exosome SNHG16 to Mediate Nasopharyngeal Carcinoma Progression through the miR-23b-5p/MCM6 Pathway.

This study aims to investigate the mechanism of tumor-derived exosomal (EVs) SNHG16 in promoting the progression of nasopharyngeal carcinoma (NPC). QRT-PCR was used to detect the expression of SNHG16, miR-23b-5p and MCM6 in NPC. MTT, flow cytometry and transwell were used to detect the effects of them on the proliferation, cycle, apoptosis and invasion ability of NPC. Transmission electron microscopy, Western blotting and BCA were used to verify the regulation of exosome secretion under different oxygen environments. Our results showed that hypoxia induces tumor-derived exosome SNHG16 to mediate NPC progression through the miR-23b-5p/MCM6 pathway.

Identification of the role of MCM6 in bladder cancer prognosis, immunotherapy response, and in vitro experimental investigation using multi-omics analysis.

BACKGROUND: The tumor-promoting effects of MCM6 in numerous tumors have been widely revealed, yet its specific role in bladder cancer (BLCA) is still elusive. The objective of this research was to explore the underlying impact of MCM6 on BLCA. METHODS: Integrating transcriptomic and proteomic data, MCM6 was identified to be strongly correlated with BLCA through weighted gene co-expression network analysis(WGCNA) and venn analyses. Then, the clinical value of MCM6 was validated with public database data. The different molecular/immune characteristics and the benefit of immunotherapy were also found in MCM6-defined subgroups. Additionally, single-cell RNA sequencing (scRNA-seq) data was choose for quantify MCM6 expression in the distinct BLCA cell types. The biological role of MCM6 were evaluated via in vitro functional experiments. RESULTS: It was testified that the MCM6 could distinguish patients outcome in TCGA and GEO cohorts. Moreover, compared with the MCM6 low-expression group, the MCM6 high-expression group was related to more tumor-promoting related pathways, aggressive phenotypes, and benefit from immunotherapy. Analysis of scRNA-seq data resulted in MCM6 was mainly expressed in BLCA epithelial cells and the proportion of MCM6-expressing tumor epithelial cells is higher than the normal epithelial cells. Moreover, vitro experiments demonstrated that MCM6 knockdown repressed proliferation, cell cycle, migration, and invasion of BLCA cells. CONCLUSION: This research indicated MCM6 is a promising marker for both prognosis and immunotherapy benefit and could promote the cells proliferation, invasion and migration in BLCA.

MCM6 is a Poor Prognostic Biomarker and Promotes Progression in Breast Cancer.

BACKGROUND: Breast cancer is the commonest global malignancy and the primary cause of carcinoma death. MCM6 is vital to carcinogenesis, but the pathogenesis of MCM6 remains unclear. METHODS: MCM6 expression in patients with breast cancer was examined through The Cancer Genome Atlas (TCGA) database, immunohistochemistry, Quantitative Real-Time PCR (qRT‒PCR) and Western blotting. The prognostic factors were assessed by the Kaplan‒Meier method and Cox regression. On the basis of the key factors selected by multivariable Cox regression analysis, a nomogram risk prediction model was adopted for clinical risk assessment. The TCGA database was utilized to determine how MCM6 is correlated with chemotherapy sensitivity, immune checkpoint-related genes (ICGs), tumor-infiltrating immune cells, along with tumor mutation burden (TMB) and methylation. The impact of MCM6 on carcinoma cells was investigated in terms of proliferation, cell cycle as well as migrating and invasive behavior through CCK assays, flow cytometry, wound healing assays, Transwell assays and xenotransplantation experiments. RESULTS: MCM6 expression was upregulated, which is closely associated with the size of the tumor (p = 0.001) and lymph node metastasis (p = 0.012) in patients with breast cancer. Multivariate analysis revealed MCM6 to be an independent risk factor for prognosis in patients with breast carcinoma. The nomograph prediction model included MCM6, age, ER, M and N stage, which displayed good discrimination with a C index of 0.817 and good calibration. Overexpression of MCM6 correlated with chemotherapy sensitivity, immune checkpoint-related genes (ICGs), tumor-infiltrating immune cells, tumor mutation burden (TMB), and methylation. Silencing MCM6 significantly inhibited proliferation, prolonged the G1 phase of the cell cycle, and restrained the proliferation, migration and invasive behavior of cancerous cells and inhibited tumor growth in vivo. CONCLUSIONS: Our research shows that MCM6 is highly expressed in breast cancer and can be used as an independent prognostic factor, which is expected to become a new target for the treatment of breast cancer in the future.

UBE3A and MCM6 synergistically regulate the proliferation and migration of lung adenocarcinoma cells.

Lung cancer is a leading cause of mortality worldwide and shows substantial clinical and biomolecular heterogeneity. Currently, specific therapeutic strategies are lacking, so effective drug targets are urgently needed. E6AP/UBE3A is a multifaceted ubiquitin ligase that controls various signaling pathways implicated in neurological diseases and various cancers; however, its role in lung cancer is incompletely understood. Here, MCM6 was identified as an interacting partner of E6AP using the yeast two-hybrid assay. MCM2 and MCM4 were then shown to interact with E6AP. E6AP knockout enhanced the ubiquitination of MCM2/4/6, suggesting that E6AP was not the E3 ubiquitin ligase for these three MCM proteins. Ablation of E6AP inhibited proliferation and migration, but had no significant effect on apoptosis in A549 and H1975 cells, and proliferation and migration inhibition was also observed in MCM6 knockdown cells. Furthermore, ablation of MCM6 and E6AP synergistically suppressed the proliferation and migration of A549 and H1975 cells. To verify the above findings in vivo, we established tumor models in nude mice and identified that the tumorigenicity of human lung adenocarcinoma (LUAD) cells was synergistically regulated by MCM6 and E6AP. Moreover, the expression levels of MCM6 and E6AP were higher in LUAD tissues than in adjacent tissues. Furthermore, the expression levels of MCM6 and E6AP were positively correlated in human LUAD samples. Thus, our study suggests that the interaction of E6AP and MCM proteins plays an important role in the progression of LUAD, which might offer potential therapeutic targets for cancer treatment.

De novo MCM6 variants in neurodevelopmental disorders: a recognizable phenotype related to zinc binding residues.

The minichromosome maintenance (MCM) complex acts as a DNA helicase during DNA replication, and thereby regulates cell cycle progression and proliferation. In addition, MCM-complex components localize to centrosomes and play an independent role in ciliogenesis. Pathogenic variants in genes coding for MCM components and other DNA replication factors have been linked to growth and developmental disorders as Meier-Gorlin syndrome and Seckel syndrome. Trio exome/genome sequencing identified the same de novo MCM6 missense variant p.(Cys158Tyr) in two unrelated individuals that presented with overlapping phenotypes consisting of intra-uterine growth retardation, short stature, congenital microcephaly, endocrine features, developmental delay and urogenital anomalies. The identified variant affects a zinc binding cysteine in the MCM6 zinc finger signature. This domain, and specifically cysteine residues, are essential for MCM-complex dimerization and the induction of helicase activity, suggesting a deleterious effect of this variant on DNA replication. Fibroblasts derived from the two affected individuals showed defects both in ciliogenesis and cell proliferation. We additionally traced three unrelated individuals with de novo MCM6 variants in the oligonucleotide binding (OB)-fold domain, presenting with variable (neuro)developmental features including autism spectrum disorder, developmental delay, and epilepsy. Taken together, our findings implicate de novo MCM6 variants in neurodevelopmental disorders. The clinical features and functional defects related to the zinc binding residue resemble those observed in syndromes related to other MCM components and DNA replication factors, while de novo OB-fold domain missense variants may be associated with more variable neurodevelopmental phenotypes. These data encourage consideration of MCM6 variants in the diagnostic arsenal of NDD.

MCM6 promotes intrahepatic cholangiocarcinoma progression by upregulating E2F1 and enhancing epithelial-mesenchymal transition.

Minichromosome maintenance complex component 6 (MCM6), a member of the MCM family, plays a pivotal role in DNA replication initiation and genome duplication of proliferating cells. MCM6 is upregulated in multiple malignancies and is considered a novel diagnostic biomarker. However, the functional contributions and prognostic value of MCM6 in intrahepatic cholangiocarcinoma (ICC) remain unexplored. In this study, we investigated the molecular function of MCM6 in ICC. Data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO, GSE107943) indicated an upregulation of MCM6 in tumor tissues. Immunohistochemical analysis performed on 115 cases of ICC samples confirmed the upregulation of MCM6 and further suggested that a high level of MCM6 expression predicted shorter overall and disease-free survival in ICC patients. Functional studies suggested that MCM6 knockdown significantly suppressed cell viability, blocked cell cycle progression and inhibited metastasis, while the enhancement of MCM6 expression promoted the proliferation and migration of ICC cells both in vitro and in vivo. Mechanistically, Gene Set Enrichment Analysis (GSEA) suggested that the epithelial-mesenchymal transition (EMT) and E2F1-correlated genes were enriched in ICC tissues with high MCM6 expression. Further verification indicated that MCM6 promoted the EMT of ICC cells via upregulating E2F1. In addition, E2F1 knockdown partially blocked the pro-malignant effects of MCM6 overexpression. In summary, MCM6 was found to be a novel prognostic and predictive marker for ICC. MCM6 promoted ICC progression via activation of E2F1-mediated EMT.

MCM6 is a critical transcriptional target of YAP to promote gastric tumorigenesis and serves as a therapeutic target.

Rationale: Hyperactivation of Hippo-Yes-associated protein (YAP) signaling pathway governs tumorigenesis of gastric cancer (GC). Here we reveal that minichromosome maintenance complex component 6 (MCM6) is a critical transcriptional target of YAP in GC. We aim to investigate the function, mechanism of action, and clinical implication of MCM6 in GC. Methods: The downstream targets of YAP were screened by RNA sequencing (RNA-seq) and microarray, and further validated by chromatin immunoprecipitation PCR and luciferase reporter assays. The clinical implication of MCM6 was assessed in multiple GC cohorts. Biological function of MCM6 was evaluated in vitro, in patient-derived organoids, and in vivo. RNA-seq was performed to unravel downstream signaling of MCM6. Potential MCM6 inhibitor was identified and the effect of MCM6 inhibition on GC growth was evaluated. Results: Integrative RNA sequencing and microarray analyses revealed MCM6 as a potential YAP downstream target in GC. The YAP-TEAD complex bound to the promoter of MCM6 to induce its transcription. Increased MCM6 expression was commonly observed in human GC tissues and predicted poor patients survival. MCM6 knockdown suppressed proliferation and migration of GC cells and patient-derived organoids, and attenuated xenograft growth and peritoneal metastasis in mice. Mechanistically, MCM6 activated PI3K/Akt/GSK3ß signaling to support YAP-potentiated gastric tumorigenicity and metastasis. Furthermore, MCM6 deficiency sensitized GC cells to chemo- or radiotherapy by causing DNA breaks and blocking ATR/Chk1-mediated DNA damage response (DDR), leading to exacerbated cell death and tumor regression. As there are no available MCM6 inhibitors, we performed high-throughput virtual screening and identified purpureaside C as a novel MCM6 inhibitor. Purpureaside C not only suppressed GC growth but also synergized with 5-fluorouracil to induce cell death. Conclusions: Hyperactivated YAP in GC induces MCM6 transcription via binding to its promoter. YAP-MCM6 axis facilitates GC progression by inducing PI3K/Akt signaling. Targeting MCM6 suppresses GC growth and sensitizes GC cells to genotoxic agents by modulating ATR/Chk1-dependent DDR, providing a promising strategy for GC treatment.

MCM6 Promotes Hepatocellular Carcinoma Progression via the Notch Pathway: Clinical, Functional, and Genomic Insights.

Objective: To evaluate the expression profile of MCM6 in HCC and the relationship between MCM6 level and clinicopathological parameters through bioinformatics analysis of several databases. Methods: MCM expression level, clinical parameters, survival data, and gene set enrichment analysis were analyzed by bioinformatics database, including Oncomine™, UALCAN, HCCDB, TCGA, cBioPortal, and LinkedOmics. Real-time PCR, western blotting, and IHC staining were conducted to identify the expression of MCM6 in HCC compared to normal liver tissues. Results: Bioinformatics analysis indicated that the mRNA of MCM6 was obviously increased in multiple cancer types, especially in HCC. MCM6 level was positively associated with multiple clinical parameters (stage 3 and grades 3 and 4) and negatively associated with patient outcomes (overall survival). Moreover, enrichment of functions and signaling pathways analysis of MCM6 suggested that MCM6 might mediate DNA replication and cellular metabolism to promote the development and progression of HCC. Furthermore, IHC staining and western blotting indicated that the MCM6 was enhanced in HCC tissue, and MCM6 could promote HCC proliferation in activating Notch pathway via WB and bioinformatic analysis. Conclusion: This study actually revealed the expression and related functions of MCM6 in HCC. Furthermore, MCM6 is a carcinogenic role in activating Notch pathway to promote HCC cell proliferation, which may be a new prognostic biomarker and therapeutic target for HCC patients.

MCM6 versus Ki-67 in diagnosis of luminal molecular subtypes of breast cancers.

BACKGROUND: Currently, breast cancers are divided into four major molecular subtypes. The distinction between the luminal A and luminal B subtypes is mainly based on the cellular proliferation indices and is assessed by the Ki-67 scoring. Due to the limitations in the assessment and expression of Ki-67, we hypothesized that minichromosome maintenance protein 6 (MCM6) might be taken as a surrogate marker to differentiate molecular subtypes and aid in more precise grading of tumors. METHODS: We performed a retrospective, cross-sectional study on 124 samples of breast cancer and 40 samples of normal breast tissue. Relevant clinical information was retrieved from the Cancer Institute database. RESULTS: MCM6 could discriminate between various categories of histologic grades, tubule formation, mitotic indices, and nuclear pleomorphism (P = 0.002 for tubule formation and P < 0.001 for other). Moreover, the MCM6 score exhibited a significant correlation with the mitotic count (P < 0.001). However, the Ki-67 score could not discriminate subgroups of the mitotic index and nuclear pleomorphism. Compared to the luminal A subtype, luminal B exhibited a higher MCM6 score (P = 0.01). Besides, MCM6 scores were higher for certain subtypes with more aggressive behaviors, such as hormone receptor (HR)-negative disease, and human epidermal growth factor receptor 2 (HER2)-enriched and triple-negative breast cancers, as there was a significantly higher MCM6 mean score in the HR-negative in comparison to the luminal breast cancers (P < 0.001). Similarly, higher MCM6 scores were observed among samples with more advanced nuclear grades, tubule formation, and overall grades. CONCLUSION: MCM6 can differentiate luminal A and luminal B subtypes and is correlated with mitotic counts. However, this study was unable to prove the superiority of MCM6 in differentiating between molecular subtypes compared to the Ki-67 score. Nevertheless, in our study, MCM6 was superior to Ki-67 in exhibiting correlations with the mitotic grade, tubule formation, and nuclear grades. More studies are needed to standardize its assessment methods, determine more robust cut-off values, and evaluate its associations with prognostic features of breast cancer.

Bioinformatics Analysis Reveals MCM3 as an Important Prognostic Marker in Cervical Cancer.

The minichromosome maintenance complex 3 (MCM3) is essential for the regulation of DNA replication and cell cycle progression. However, the expression and prognostic values of MCM3 in cervical cancer (CC) have not been well-studied. Herein, we investigated the expression patterns and survival data of MCM3 in cervical cancer patients from the ONCOMINE, GEPIA, Human Protein Atlas, UALCAN, Kaplan-Meier Plotter, and LinkedOmics databases. The expression level of MCM3 is negatively correlated with advanced tumor stage and metastatic status. Specifically, MCM3 is significantly differentially expressed between patients in stage 1 and stage 3 cervical cancer with p value 0.0138. Similarly, the p values between stage 1 and stage 4 cervical cancer, between stage 2 and stage 3, and between stage 2 and stage 4 are 0.00089, 0.0244, and 0.00197, respectively. Not only that, cervical cancer patients with high mRNA expression of MCM3 may indicate longer overall survival but indicate shorter relapse-free survival. PRIM2 and MCM6 are positively correlated genes of MCM3. Bioinformatics analysis revealed that MCM3 might be considered a biological indicator for prognostic evaluation of cervical cancer. However, it is currently limited to bioinformatics analysis, and more clinical tissue specimens and cell experiments are needed to further explore the role of MCM3 in the occurrence and progression of cervical cancer.

A novel cell-cycle-regulated interaction of the Bloom syndrome helicase BLM with Mcm6 controls replication-linked processes.

The Bloom syndrome DNA helicase BLM contributes to chromosome stability through its roles in double-strand break repair by homologous recombination and DNA replication fork restart during the replication stress response. Loss of BLM activity leads to Bloom syndrome, which is characterized by extraordinary cancer risk and small stature. Here, we have analyzed the composition of the BLM complex during unperturbed S-phase and identified a direct physical interaction with the Mcm6 subunit of the minichromosome maintenance (MCM) complex. Using distinct binding sites, BLM interacts with the N-terminal domain of Mcm6 in G1 phase and switches to the C-terminal Cdt1-binding domain of Mcm6 in S-phase, with a third site playing a role for Mcm6 binding after DNA damage. Disruption of Mcm6-binding to BLM in S-phase leads to supra-normal DNA replication speed in unperturbed cells, and the helicase activity of BLM is required for this increased replication speed. Upon disruption of BLM/Mcm6 interaction, repair of replication-dependent DNA double-strand breaks is delayed and cells become hypersensitive to DNA damage and replication stress. Our findings reveal that BLM not only plays a role in the response to DNA damage and replication stress, but that its physical interaction with Mcm6 is required in unperturbed cells, most notably in S-phase as a negative regulator of replication speed.

MCM6 indicates adverse tumor features and poor outcomes and promotes G1/S cell cycle progression in neuroblastoma.

BACKGROUND: Minichromosome maintenance complex component 6 (MCM6), as an important replication permission factor, is involved in the pathogenesis of various tumors. Here we studied the expression of MCM6 in neuroblastoma and its influence on tumor characteristics and prognosis. METHODS: Publicly available datasets were used to explore the influence of the differential expression of MCM6 on neuroblastoma tumor stage, risk and prognosis. In cell experiments, human neuroblastoma cell lines SK-N-SH and SK-N-BE [ (2)] were utilized to verify the ability of MCM6 to promote cell proliferation, migration and invasion. We further explored the possible molecular mechanism of MCM6 affecting the phenotype of neuroblastoma cells by mutual verification of RNA-seq and western blotting, and flow cytometry to inquire about its potential specific roles in the cell cycle. RESULTS: Through multiple datasets mining, we found that high expression of MCM6 was positively correlated with elevated tumor stage, high risk and poor prognosis in neuroblastoma. At the cellular level, neuroblastoma cell proliferation, migration and invasion were significantly inhibited after MCM6 was interfered by siRNA. Mutual verification of RNA-seq and western blotting suggested that the downstream cell cycle-related genes were differentially expressed after MCM6 interference. Flow cytometric analysis revealed that neuroblastoma cells were blocked in G1/S phase after MCM6 interference. CONCLUSION: MCM6 is considered to be the driving force of G1/S cell cycle progression, and it is also a prognostic marker and a potential novel therapeutic target in neuroblastoma.

Methylation-dependent MCM6 repression induced by LINC00472 inhibits triple-negative breast cancer metastasis by disturbing the MEK/ERK signaling pathway.

Long noncoding RNAs (lncRNAs) have been identified to be dysregulated in multiple cancer types, which are speculated to be of vital significance in regulating several hallmarks of cancer biology. Triple-negative breast cancer (TNBC) is acknowledged as an aggressive subtype of breast cancer. In this study, we found the lncRNA LINC00472 was poorly expressed in TNBC tissues and cells. Overexpression of LINC00472 could inhibit the proliferation, invasion and migration of MDA-MB-231 cells. On the contrary, minichromosome maintenance complex component 6 (MCM6) was highly expressed in TNBC tissues and MDA-MB-231 cells due to suppressed methylation. LINC00472 induced site-specific DNA methylation and reduced the MCM6 expression by recruiting DNA methyltransferases into the MCM6 promoter. Since the restoration of MCM6 weakened the tumor-suppressive effect of LINC00472 on MDA-MB-231 cells, LINC00472 potentially acted as a tumor suppressor by inhibiting MCM6. In addition, in vivo experiments further substantiated that overexpression of LINC00472 inhibited tumor growth and metastasis to lungs by decreasing the expression of MCM6. Overall, the present study demonstrated that LINC00472-mediated epigenetic silencing of MCM6 contributes to the prevention of tumorigenesis and metastasis in TNBC, providing an exquisite therapeutic target for TNBC.

Role of Amygdalin in Blocking DNA Replication in Breast Cancer In Vitro.

BACKGROUND: Amygdalin has anticancer benefits because of its active component, hydrocyanic acid. However, the underlying molecular mechanism is unclear. OBJECTIVE: This study aimed to investigate the molecular mechanism by which amygdalin exerts antiproliferative effects in the human Michigan Cancer Foundation-7 (MCF-7) breast cancer cell line. METHODS: MCF-7 cells were exposed to amygdalin at a particular IC50 value for 24 and 48 hours and compared to non-treated cells. An Affymetrix whole-transcript expression array was used to analyze the expression of 32 genes related to DNA replication. RESULTS: Among the 32 genes, amygdalin downregulated the expression of 16 genes and 19 genes by >1.5-fold at 24 and 48 hours, respectively. At 24 hours, the downregulated genes from the DNA polymerase α-primase complex were POLA1, POLA2, PRIM1, and PRIM2; DNA polymerase δ complex: POLD3; DNA polymerase ε complex: POLE4, Minichromosome Maintenance protein (MCM) complex (helicase): MCM2, MCM3, MCM4, MCM6, and MCM7; clamp and clamp loader: PCNA; nuclease: FEN1; and DNA ligase: LIG1. At 48 hours, the downregulated genes from the DNA polymerase α-primase complex were POLA1, POLA2, and PRIM1; DNA polymerase δ complex: POLD3; DNA polymerase ε complex: POLE and POLE2; MCM complex (helicase): MCM2, MCM3, MCM4, MCM5, MCM6, and MCM7; clamp and clamp loader: PCNA, RFC2, and RFC3; RNase H: RNASEH2A; nucleases: DNA2 and FEN1; and DNA ligase: LIG1. CONCLUSION: Amygdalin treatment caused downregulation of several genes that play critical roles in DNA replication in the MCF-7 cell line. Thus, it might be useful as an anticancer agent.

The DNA replication regulator MCM6: An emerging cancer biomarker and target.

MCM6 is a significant DNA replication regulator that plays a crucial role in sustaining the cell cycle. In many cancer cells, MCM6 expression is enhanced. For example, persistently increased expression of MCM6 promotes the formation, development and progression of hepatocellular carcinoma (HCC). Up- and down-regulation studies have indicated that MCM6 regulates cell cycle, proliferation, metastasis, immune response and the maintenance of the DNA replication system. MCM6 can also regulate downstream signaling such as MEK/ERK thus promoting carcinogenesis. Accordingly, MCM6 may represent a sensitive and specific biomarker to predict adverse progression and poor outcome. Furthermore, inhibition of MCM6 may be an effective cancer treatment. The present review summarizes the latest results on the inactivating and activating functions of MCM6, underlining its function in carcinogenesis. Further studies of the carcinogenic functions of MCM6 may provide novel insight into cancer biology and shed light on new approaches for cancer diagnosis and treatment.

High MCM6 Expression as a Potential Prognostic Marker in Clear-cell Renal Cell Carcinoma.

AIM: Minichromosome maintenance (MCM) proteins are involved in initiation of DNA replication and cell-cycle progression. Loss of MCM function results in genomic instability and causes carcinogenesis. Among MCM genes, the role and prognostic value of MCM6 expression in clear-cell renal cell carcinoma (ccRCC) has not been elucidated. MATERIALS AND METHODS: We assessed the mRNA expression level of MCM6 using the Gene Expression Profiling Interactive Analysis database and investigated MCM6 protein expression by immunohistochemistry in 238 ccRCC cases. RESULTS: High MCM6 expression was significantly associated with increasing tumor size, pT, stage, tumor necrosis, and metastasis. Furthermore, high MCM6 expression was significantly associated with shorter overall and disease-free survival, and was an independent unfavorable prognostic marker. Regarding patients with metastasis, high MCM6-expressing ccRCC conferred significantly shorter survival than for those with low expression. CONCLUSION: A high MCM6 expression level may be a promising biomarker to predict tumor progression, metastasis, and survival in patients with ccRCC.

Minichromosome maintenance 6 complex component identified by bioinformatics analysis and experimental validation in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC), the main subtype of esophageal cancer (EC), is a common lethal type of cancer with a high mortality rate. The aim of the present study was to select key relevant genes and identify potential mechanisms involved in the development of ESCC based on bioinformatics analysis. Minichromosome maintenance 6 complex component (MCM6) has been identified to be upregulated in multiple malignancies; however, its contributions to ESCC remain unclear. For the purposes of the present study, four datasets were downloaded from the Gene Expression Omnibus (GSE63941, GSE26886, GSE17351 and GSE77861), and the intersection of the differentially expressed genes was obtained using a Venn diagram. The protein­protein interaction was then constructed, and the modules were verified by Cytoscape, in which the key genes have a high connectivity degree with other genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway were subsequently filtered out to analyze the development of ESCC. MCM6, an upregulated gene, was selected and connected with most of the other genes, for further research validation. The expression levels of MCM6 were then assessed using the Oncomine, GEPIA and UALCAN databases and validated in both ESCC tissues samples and cell lines by immunohistochemistry and RT­qPCR. Cell counting kit­8 (CCK­8), flow cytometry, wound healing and Transwell assays were used to determine the proliferation, apoptosis, cell cycle, migration and invasion of ESCC cells. A total of 24 genes were identified by a series of bioinformatics analyses and the results revealed that the genes were associated with DNA replication and cell cycle. Experimental validation revealed that MCM6 expression was significantly elevated in both ESCC tissues and cell lines. The results were consistent with those of bioinformatics analysis. Furthermore, the knockdown of MCM6 inhibited cell proliferation, migration and invasion and promoted cell apoptosis, and made cells arrested in S stage. In summary, the findings of bioinformatics analysis provided a novel hypothesis for ESCC progression. In particular, the aberrantly elevated expression of MCM6 is a potential biomarker for ESCC diagnosis and treatment.