Links between DNA Replication, Stem Cells and Cancer. Genes (Basel). 2017;8. [PMID: 28125050 PMCID: PMC5333035 DOI: 10.3390/genes8020045]

Selective Termination of Autophagy-Dependent Cancers

The goal of cancer research is to identify characteristics of cancer cells that allow them to be selectively eliminated without harming the host. One such characteristic is autophagy dependence. Cancer cells survive, proliferate, and metastasize under conditions where normal cells do not. Thus, the requirement in cancer cells for more energy and macromolecular biosynthesis can evolve into a dependence on autophagy for recycling cellular components. Recent studies have revealed that autophagy, as well as different forms of cellular trafficking, is regulated by five phosphoinositides associated with eukaryotic cellular membranes and that the enzymes that synthesize them are prime targets for cancer therapy. For example, PIKFYVE inhibitors rapidly disrupt lysosome homeostasis and suppress proliferation in all cells. However, these inhibitors selectively terminate PIKFYVE-dependent cancer cells and cancer stem cells with not having adverse effect on normal cells. Here, we describe the biochemical distinctions between PIKFYVE-sensitive and -insensitive cells, categorize PIKFYVE inhibitors into four groups that differ in chemical structure, target specificity and efficacy on cancer cells and normal cells, identify the mechanisms by which they selectively terminate autophagy-dependent cancer cells, note their paradoxical effects in cancer immunotherapy, and describe their therapeutic applications against cancers.

Pharmacokinetics and drug-likeness of anti-cancer traditional Chinese medicine: molecular docking and molecular dynamics simulation study

MCM7 (Minichromosome Maintenance Complex Component 7) is a component of the DNA replication licensing factor, which controls DNA replication. The MCM7 protein is linked to tumor cell proliferation and has a function in the development of several human cancers. Several types of cancer may be treated by inhibiting the protein, as it is strongly produced throughout this process. Significantly, Traditional Chinese Medicine (TCM), which has a long history of clinical adjuvant use against cancer, is rapidly gaining traction as a valuable medical resource for the development of novel cancer therapies, including immunotherapy. Therefore, the goal of the research was to find small molecular therapeutic candidates against the MCM7 protein that may be used to treat human cancers. A computational-based virtual screening of 36,000 natural TCM libraries is carried out for this goal using a molecular docking and dynamic simulation technique. Thereby, ∼8 novel potent compounds i.e., ZINC85542762, ZINC95911541, ZINC85542617, ZINC85542646, ZINC85592446, ZINC85568676, ZINC85531303, and ZINC95914464 were successfully shortlisted, each having the capacity to penetrate the cell as potent inhibitors for MCM7 to curb this disorder. These selected compounds were found to have high binding affinities compared to the reference (AGS compound) i.e. < -11.0 kcal/mol. ADMET and pharmacological properties showed that none of these 8 compounds poses any toxic property (carcinogenicity) and have anti-metastatic, and anticancer activity. Additionally, MD simulations were run to assess the compounds' stability and dynamic behavior with the MCM7 complex for about 100 ns. Finally, ZINC95914464, ZINC95911541, ZINC85568676, ZINC85592446, ZINC85531303, and ZINC85542646 are identified as highly stable within the complex throughout the 100 ns simulations. Moreover, the results of binding free energy suggested that the selected virtual hits significantly bind to the MCM7 which implied these compounds may act as a potential MCM7 inhibitor. However, in vitro testing protocols are required to further support these results. Further, assessment through various lab-based trial methods can assist with deciding the action of the compound that will give options in contrast to human cancer immunotherapy.Communicated by Ramaswamy H. Sarma.

A pyroptosis-related lncRNA-based prognostic index for hepatocellular carcinoma by relative expression orderings

Background

Hepatocellular carcinoma (HCC) is an invasive malignant tumor, and pyroptosis makes an important contribution to the pathology and progression of liver cancer. Many prognostic models have been proposed for HCC based on the quantitative expression level of candidate genes, which are unsuitable for clinical application due to their vulnerability against experimental batch effects. The aim of this study was to develop a novel pyroptosis-related long non-coding RNA (lncRNA)-based prognostic index (PLPI) for HCC based on relative expression orderings (REOs).

Methods

Firstly, the pyroptosis-related lncRNAs were identified through the Wilcoxon rank-sum test and gene co-expression analyses. Then, the novel prognostic model PLPI was constructed by pyroptosis-related lncRNA pairs, which were identified by multiple machine learning algorithms. Gene set enrichment, somatic mutation, and drug sensitivity analyses were conducted to measure the differences between high- and low-risk patients. Multiple immune analyses were used to explore the association between PLPI and the immunological microenvironment.

Results

In this study, a novel prognostic model PLPI based on 10 pyroptosis-related lncRNA pairs was constructed, which was proven to be an independent prognostic risk factor. The receiver operating characteristic (ROC) curves showed that the model had a good prognostic ability in the training, testing, and external set, respectively [5-year area under the curve (AUC) =0.73, 5-year AUC =0.81, 4-year AUC =0.79]. The results of survival, somatic mutation, and immune analyses showed that the patients in the low-risk group had a better prognosis, lower rates of somatic mutation, and better immune cell infiltration. Personalized chemotherapeutic drugs were also identified for the patients with HCC.

Conclusions

The novel PLPI not only greatly predicted the prognosis of patients with HCC but could also offer novel ideas and approaches for the therapeutic management of HCC.

Resistance to Chemotherapeutic 5-Fluorouracil Conferred by Modulation of Heterochromatic Integrity through Ino80 Function in Fission Yeast

5-Fluorouracil (5-FU) is a conventional chemotherapeutic drug widely used in clinics worldwide, but development of resistance that compromises responsiveness remains a major hurdle to its efficacy. The mechanism underlying 5-FU resistance is conventionally attributed to the disruption of nucleotide synthesis, even though research has implicated other pathways such as RNA processing and chromatin dysregulation. Aiming to clarify resistance mechanisms of 5-FU, we tested the response of a collection of fission yeast (Schizosaccharomyces pombe) null mutants, which confer multiple environmental factor responsiveness (MER). Our screen identified disruption of membrane transport, chromosome segregation and mitochondrial oxidative phosphorylation to increase cellular susceptibility towards 5-FU. Conversely, we revealed several null mutants of Ino80 complex factors exhibited resistance to 5-FU. Furthermore, attenuation of Ino80 function via deleting several subunit genes reversed loss of chromosome-segregation fidelity in 5-FU in the loss-of-function mutant of the Argonaute protein, which regulates RNA interference (RNAi)-dependent maintenance of pericentromeric heterochromatin. Our study thus uncovered a critical role played by chromatin remodeling Ino80 complex factors in 5-FU resistance, which may constitute a possible target to modulate in reversing 5-FU resistance.

In silico screening of inhibitors against human dihydrofolate reductase to identify potential anticancer compounds

In all species, dihydrofolate reductase (DHFR) is an essential enzyme that regulates the cellular amount of tetrahydrofolate. Human DHFR (hDHFR) activity inhibition results in tetrahydrofolate depletion and cell death. This property has made hDHFR a therapeutic target for cancer. Methotrexate is a well-known hDHFR inhibitor, but its administration has shown some light to severe adverse effects. Therefore, we aimed to find new potential hDHFR inhibitors using structure-based virtual screening, ADMET prediction, molecular docking, and molecular dynamics simulations. Here, we used the PubChem database to find all compounds with at least 90% structural similarity to known natural DHFR inhibitors. To explore their interaction pattern and estimate their binding affinities, the screened compounds (2023) were subjected to structure-based molecular docking against hDHFR. The fifteen compounds that showed higher binding affinity to the hDHFR than the reference compound (methotrexate) displayed important molecular orientation and interactions with key residues in the enzyme's active site. These compounds were subjected to Lipinski and ADMET prediction. PubChem CIDs: 46886812 and 638190 were identified as putative inhibitors. In addition, molecular dynamics simulations revealed that the binding of compounds (CIDs: 46886812 and 63819) stabilized the hDHFR structure and caused minor conformational changes. Our findings suggest that two compounds (CIDs: 46886812 and 63819) could be promising potential inhibitors of hDHFR in cancer therapy.Communicated by Ramaswamy H. Sarma.

Unscheduled DNA replication in G1 causes genome instability and damage signatures indicative of replication collisions

DNA replicates once per cell cycle. Interfering with the regulation of DNA replication initiation generates genome instability through over-replication and has been linked to early stages of cancer development. Here, we engineer genetic systems in budding yeast to induce unscheduled replication in a G1-like cell cycle state. Unscheduled G1 replication initiates at canonical S-phase origins. We quantifiy the composition of replisomes in G1- and S-phase and identified firing factors, polymerase α, and histone supply as factors that limit replication outside S-phase. G1 replication per se does not trigger cellular checkpoints. Subsequent replication during S-phase, however, results in over-replication and leads to chromosome breaks and chromosome-wide, strand-biased occurrence of RPA-bound single-stranded DNA, indicating head-to-tail replication collisions as a key mechanism generating genome instability upon G1 replication. Low-level, sporadic induction of G1 replication induces an identical response, indicating findings from synthetic systems are applicable to naturally occurring scenarios of unscheduled replication initiation.

Integrated 5-hydroxymethylcytosine and fragmentation signatures as enhanced biomarkers in lung cancer

Background

Lung cancer is one of most common cancers worldwide, with a 5-year survival rate of less than 20%, which is mainly due to late-stage diagnosis. Noninvasive methods using 5-hydroxymethylation of cytosine (5hmC) modifications and fragmentation profiles from 5hmC cell-free DNA (cfDNA) sequencing provide an opportunity for lung cancer detection and management.

Results

A total of 157 lung cancer patients were recruited to generate the largest lung cancer cfDNA 5hmC dataset, which mainly consisted of 62 lung adenocarcinoma (LUAD), 48 lung squamous cell carcinoma (LUSC) and 25 small cell lung cancer (SCLC) patients, with most patients (131, 83.44%) at advanced tumor stages. A 37-feature 5hmC model was constructed and validated to distinguish lung cancer patients from healthy controls, with areas under the curve (AUCs) of 0.8938 and 0.8476 (sensitivity = 87.50% and 72.73%, specificity = 83.87% and 80.60%) in two distinct validation sets. Furthermore, fragment profiles of cfDNA 5hmC datasets were first explored to develop a 48-feature fragmentation model with good performance (AUC = 0.9257 and 0.822, sensitivity = 87.50% and 78.79%, specificity = 80.65% and 76.12%) in the two validation sets. Another diagnostic model integrating 5hmC signals and fragment profiles improved AUC to 0.9432 and 0.8639 (sensitivity = 87.50% and 83.33%, specificity = 90.30% and 77.61%) in the two validation sets, better than models based on either of them alone and performing well in different stages and lung cancer subtypes. Several 5hmC markers were found to be associated with overall survival (OS) and disease-free survival (DFS) based on gene expression data from The Cancer Genome Atlas (TCGA).

Conclusions

Both the 5hmC signal and fragmentation profiles in 5hmC cfDNA data are sensitive and effective in lung cancer detection and could be incorporated into the diagnostic model to achieve good performance, promoting research focused on clinical diagnostic models based on cfDNA 5hmC data.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01233-7.

Potential Prognostic Biomarkers of NIMA (Never in Mitosis, Gene A)-Related Kinase (NEK) Family Members in Breast Cancer

Breast cancer remains the most common malignant cancer in women, with a staggering incidence of two million cases annually worldwide; therefore, it is crucial to explore novel biomarkers to assess the diagnosis and prognosis of breast cancer patients. NIMA-related kinase (NEK) protein kinase contains 11 family members named NEK1-NEK11, which were discovered from Aspergillus Nidulans; however, the role of NEK family genes for tumor development remains unclear and requires additional study. In the present study, we investigate the prognosis relationships of NEK family genes for breast cancer development, as well as the gene expression signature via the bioinformatics approach. The results of several integrative analyses revealed that most of the NEK family genes are overexpressed in breast cancer. Among these family genes, NEK2/6/8 overexpression had poor prognostic significance in distant metastasis-free survival (DMFS) in breast cancer patients. Meanwhile, NEK2/6 had the highest level of DNA methylation, and the functional enrichment analysis from MetaCore and Gene Set Enrichment Analysis (GSEA) suggested that NEK2 was associated with the cell cycle, G2M checkpoint, DNA repair, E2F, MYC, MTORC1, and interferon-related signaling. Moreover, Tumor Immune Estimation Resource (TIMER) results showed that the transcriptional levels of NEK2 were positively correlated with immune infiltration of B cells and CD4+ T Cell. Collectively, the current study indicated that NEK family genes, especially NEK2 which is involved in immune infiltration, and may serve as prognosis biomarkers for breast cancer progression.

Developmental Acquisition of p53 Functions

Remarkably, the p53 transcription factor, referred to as “the guardian of the genome”, is not essential for mammalian development. Moreover, efforts to identify p53-dependent developmental events have produced contradictory conclusions. Given the importance of pluripotent stem cells as models of mammalian development, and their applications in regenerative medicine and disease, resolving these conflicts is essential. Here we attempt to reconcile disparate data into justifiable conclusions predicated on reports that p53-dependent transcription is first detected in late mouse blastocysts, that p53 activity first becomes potentially lethal during gastrulation, and that apoptosis does not depend on p53. Furthermore, p53 does not regulate expression of genes required for pluripotency in embryonic stem cells (ESCs); it contributes to ESC genomic stability and differentiation. Depending on conditions, p53 accelerates initiation of apoptosis in ESCs in response to DNA damage, but cell cycle arrest as well as the rate and extent of apoptosis in ESCs are p53-independent. In embryonic fibroblasts, p53 induces cell cycle arrest to allow repair of DNA damage, and cell senescence to prevent proliferation of cells with extensive damage.

Computational Screening of Natural Compounds for Identification of Potential Anti-Cancer Agents Targeting MCM7 Protein

Minichromosome maintenance complex component 7 (MCM7) is involved in replicative licensing and the synthesis of DNA, and its overexpression is a fascinating biomarker for various cancer types. There is currently no effective agent that can prevent the development of cancer caused by the MCM7 protein. However, on the molecular level, inhibiting MCM7 lowers cancer-related cellular growth. With this purpose, this study screened 452 biogenic compounds extracted from the UEFS Natural Products dataset against MCM protein by using the in silico art of technique. The hit compounds UEFS99, UEFS137, and UEFS428 showed good binding with the MCM7 protein with binding energy values of −9.95, −8.92, and −8.71 kcal/mol, which was comparatively higher than that of the control compound ciprofloxacin (−6.50). The hit (UEFS99) with the minimum binding energy was picked for molecular dynamics (MD) simulation investigation, and it demonstrated stability at 30 ns. Computational prediction of physicochemical property evaluation revealed that these hits are non-toxic and have good drug-likeness features. It is suggested that hit compounds UEFS99, UEFS137, and UEFS428 pave the way for further bench work validation in novel inhibitor development against MCM7 to fight the cancers.

Ubiquitin-Specific Protease 29 Regulates Cdc25A-Mediated Tumorigenesis

Cell division cycle 25A (Cdc25A) is a dual-specificity phosphatase that is overexpressed in several cancer cells and promotes tumorigenesis. In normal cells, Cdc25A expression is regulated tightly, but the changes in expression patterns in cancer cells that lead to tumorigenesis are unknown. In this study, we showed that ubiquitin-specific protease 29 (USP29) stabilized Cdc25A protein expression in cancer cell lines by protecting it from ubiquitin-mediated proteasomal degradation. The presence of USP29 effectively blocked polyubiquitination of Cdc25A and extended its half-life. CRISPR-Cas9-mediated knockdown of USP29 in HeLa cells resulted in cell cycle arrest at the G0/G1 phase. We also showed that USP29 knockdown hampered Cdc25A-mediated cell proliferation, migration, and invasion of cancer cells in vitro. Moreover, NSG nude mice transplanted with USP29-depleted cells significantly reduced the size of the tumors, whereas the reconstitution of Cdc25A in USP29-depleted cells significantly increased the tumor size. Altogether, our results implied that USP29 promoted cell cycle progression and oncogenic transformation by regulating protein turnover of Cdc25A.

Kinesin Superfamily Member 18B (KIF18B) Promotes Cell Proliferation in Colon Adenocarcinoma

BACKGROUND

The role of kinesin superfamily proteins (KIFs) has been reported in a variety of tumors and KIFs contributed to the proliferation of cancer cells. But few studies were focus on colon adenocarcinoma.

METHODS

Through bioinformatics analysis and immunohistochemistry (IHC) assays, the expression of KIF18B in colon adenocarcinoma tissues was determined. Stable KIF18B-depleted cell lines were constructed using lentivirus-mediated shRNA of KIF18B. Cell colony formation assay and CCK8 assay were performed to assess cell proliferation degree, and the expression level of KI67 and PCNA was used to indicate cell proliferation in vitro and verified using xenograft tumors in vivo.

RESULTS

KIF18B is highly expressed in colon adenocarcinoma tissues and has a negative correlation with the prognosis and tumor grade of colon adenocarcinoma. Interfering with KIF18B inhibits cell proliferation in vitro and in vivo.

CONCLUSION

KIF18B can be used as a prognostic marker for colon adenocarcinoma and may be a therapeutic target for colon adenocarcinoma treatment.

Increased E2F2 predicts poor prognosis in patients with HCC based on TCGA data

Background

The E2F family of transcription factor 2 (E2F2) plays an important role in the development and progression of various tumors, but its association with hepatocellular carcinoma (HCC) remains unknown. Our study aimed to investigate the role and clinical significance of E2F2 in HCC.

Methods

HCC raw data were extracted from The Cancer Genome Atlas (TCGA). Wilcoxon signed-rank test, Kruskal-Wallis test and logistic regression were applied to analyze the relationship between the expression of E2F2 and clinicopathologic characteristics. Cox regression and Kaplan-Meier were employed to evaluate the correlation between clinicopathologic features and survival. The biological function of E2F2 was annotated by Gene Set Enrichment Analysis (GSEA).

Results

The expression of E2F2 was increased in HCC samples. The expression of elevated E2F2 in HCC samples was prominently correlated with histologic grade (OR = 2.62 for G3–4 vs. G1–2, p = 1.80E-05), clinical stage (OR = 1.74 for III-IV vs. I-II, p = 0.03), T (OR = 1.64 for T3–4 vs.T1–2, p = 0.04), tumor status (OR = 1.88 for with tumor vs. tumor free, p = 3.79E-03), plasma alpha fetoprotein (AFP) value (OR = 3.18 for AFP ≥ 400 vs AFP<20, p = 2.16E-04; OR = 2.50 for 20 ≤ AFP<400 vs AFP<20, p = 2.56E-03). Increased E2F2 had an unfavorable OS (p = 7.468e− 05), PFI (p = 3.183e− 05), DFI (p = 0.001), DSS (p = 4.172e− 05). Elevated E2F2 was independently bound up with OS (p = 0.004, hazard ratio [HR] = 2.4 (95% CI [1.3–4.2])), DFI (P = 0.029, hazard ratio [HR] = 2.0 (95% CI [1.1–3.7])) and PFI (P = 0.005, hazard ratio [HR] = 2.2 (95% CI [1.3–3.9])). GSEA disclosed that cell circle, RNA degradation, pyrimidine metabolism, base excision repair, aminoacyl tRNA biosynthesis, DNA replication, p53 signaling pathway, nucleotide excision repair, ubiquitin-mediated proteolysis, citrate cycle TCA cycle were notably enriched in E2F2 high expression phenotype.

Conclusions

Elevated E2F2 can be a promising independent prognostic biomarker and therapeutic target for HCC. Additionally, cell cycle, pyrimidine metabolism, DNA replication, p53 signaling pathway, ubiquitin-mediated proteolysis, the citrate cycle TCA cycle may be the key pathway by which E2F2 participates in the initial and progression of HCC.

Keratoacanthoma, committed stem cells and neoplastic aberrant infundibulogenesis integral to formulating a conceptual model for an infundibulocystic pathway to squamous cell carcinoma

Keratoacanthomas (KAs) are distinctive tumors that are defined by their clinical and histopathological features. Their relationship and distinction from squamous cell carcinoma (SCC), however, remain controversial. All cytogenic and immunohistochemical markers that have been applied in this quest have failed. A close relationship of KAs to hair follicles has been recognized. The descriptive term infundibulocystic or infundibular SCC was introduced to define a more broad-based pathway encompassing KAs. The follicular infundibulum roles in respect to neoplasia and wound healing are important elements in understanding the pathogenesis of KAs. Mouse models for KA have provided insights into the relationship of KA to follicles and SCCs. These advances and together with the diverse clinical and histopathological aspects of KA have contributed to the formulation of a conceptual pathway. The central element is that ultraviolet (UV)-mutated or activated committed infundibular stem cells are driven by the combination of a mutated oncogenic RAS pathway linked with the Wnt/beta-catenin pathway responsible for stem cell maintenance, hair follicle development, wound healing and driving KA proliferation and terminal keratinization. The existence and activation of this mutated pathway may form the basis of the paradoxical emergence of KAs and SCCs in patients receiving BRAF and PD-1 inhibitor therapy.

MCM10 Acts as a Potential Prognostic Biomarker and Promotes Cell Proliferation in Hepatocellular Carcinoma: Integrated Bioinformatics Analysis and Experimental Validation

Background

Hepatocellular carcinoma (HCC) is one of the most common human malignant tumors. The prognosis of HCC patients is still unsatisfying. Thus, it is of great importance to identify novel molecules and functional pathways associated with the pathophysiology of HCC. In this study, we performed the integrated bioinformatics analysis and experiment validation to identify novel biomarkers in the prognosis and progression of HCC.

Materials and Methods

Gene expression profiles were obtained from Gene Expression Omnibus database (GSE33294) for the screening of the differentially expressed genes (DEGs) between HCC tissues and matched non-tumor tissues. The DEGs were subjected to Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and Gene Set Enrichment Analysis (GSEA). The key genes in HCC were further subjected to overall survival analysis of HCC patients. The in vitro functional studies were performed to validate the biological functions of the key gene in HCC cell progression.

Results

A total of 2,334 DEGs were screened from GSE33294 dataset, including 1,120 up-regulated and 1,214 down-regulated genes. GO, KEGG and GSEA results showed that DEGs are significantly associated with the biological process of cell cycle, cell division and DNA replication. The Kaplan–Meier survival analysis results showed that the key genes from the minichromosome maintenance protein complex (MCM) family including MCM8, MCM10, MCM2, MCM3, MCM4, MCM6 and MCM7 were significantly correlated with the overall survival of the HCC patients. Further validation studies showed that MCM10 was significantly up-regulated in the HCC cell lines, and knockdown of MCM10 significantly suppressed cell proliferation as determined by the cell counting kit-8 and BrdU incorporation assays and increased the caspase-3 activity of HCC cells.

Conclusion

The comprehensive bioinformatics analysis identified several key genes that were associated with the prognosis of HCC patients. The validation study results indicated that MCM10 may be an important predictor for poorer prognosis of HCC patients and may act as an oncogene to promote HCC cell progression.

Onycholemmal variant of keratoacanthoma centrifugum marginatum as an expression of mutated committed stem cells in a conceptual pathway

We describe a 43-year-old woman with a 10-year history of grossly hyperkeratotic nodules which progressively extended over the right ring finger. These involuted leaving pale, atrophic skin in their wake. At presentation, the advancing border had an arciform series of nodules in the pattern of keratoacanthoma centrifugum marginatum. The presence of filiform keratinisation that encased the nail plate, gross onychogryphotic masses of keratin on the ventral finger surface and a flat nail-like plate of keratin on the dorsal finger surface were distinctive features. Skin biopsy showed epidermal acanthosis, gross papillomatous cutaneous horn formation that had onycholemmal features. The pathology differed from keratoacanthoma and was not crateriform or infundibulocystic. Although HPV was not detected on immunohistochemistry, pathogenesis may still represent an HPV-related transfection of onycholemmal keratin committed stem cells producing an onycholemmal variant of keratoacanthoma centrifugum marginatum. A conceptual model linked to advances in follicular stem cell biology is formulated to explore this case.

Wnt-Responsive Stem Cell Fates in the Oral Mucosa

Epithelia of the oral cavity exhibit variations in morphologies and turnover rates. Are these differences related to environment or to region-specific stem cell populations? A lineage-tracing strategy allowed visualization of Wnt-responsive cells, and their progeny, in the hard and soft palates. In both anatomic locations, Wnt-responsive basal cells self-renewed and gave rise to supra-basal cells. Palatal injuries triggered an enlargement of this population, and their descendants were responsible for wound re-epithelialization. Compared with the hard palate, soft palate stem cells exhibited an earlier, more robust burst in proliferation, culminating in significantly faster repair. Thereafter, excess Wnt-responsive basal cells were removed, and stem cell numbers were restored back to homeostatic level. Thus, we uncovered a stem cell population in oral mucosa, and its relative abundance is correlate with the rate of oral wound healing. Besides the activation during injury, an endogenous mechanism exists to constrain the stem cell pool after repair.

Accelerated Evolution in Distinctive Species Reveals Candidate Elements for Clinically Relevant Traits, Including Mutation and Cancer Resistance

The identity of most functional elements in the mammalian genome and the phenotypes they impact are unclear. Here, we perform a genomewide comparative analysis of patterns of accelerated evolution in species with highly distinctive traits to discover candidate functional elements for clinically important phenotypes. We identify accelerated regions (ARs) in the elephant, hibernating bat, orca, dolphin, naked mole rat, and thirteen-lined ground squirrel lineages in mammalian conserved regions, uncovering ~33,000 elements that bind hundreds of different regulatory proteins in humans and mice. ARs in the elephant, the largest land mammal, are uniquely enriched near elephant DNA damage response genes. The genomic hotspot for elephant ARs is the E3 ligase subunit of the Fanconi anemia complex, a master regulator of DNA repair. Additionally, ARs in the six species are associated with specific human clinical phenotypes that have apparent concordance with overt traits in each species.

The Small Bowel Cancer Incidence Enigma

Although the small bowel is a vast organ with a highly proliferative epithelium, the incidence of small bowel cancers is surprisingly low. Many factors could be involved in this unexpected cancer incidence, including difficult access to the exploration of the small bowel mucosa, which might lead to missed diagnoses of non-obstructive and non-bleeding small tumours. Moreover, possible factors that influence the low incidence include more efficient machinery of DNA replication and DNA repair enzymes, peculiarities in microbiota components, competence of the immune system, and the speed of intestinal transit. Importantly, the answer for the enigmatic risk of driver mutations caused by replication errors may be hidden in the small bowel, which is an obscure part of digestive tract that is usually inaccessible by endoscopic or colonoscopic conventional investigations. These observations warrant the necessity of an urgent exploration of small bowel features, including the evaluation of DNA replication controls and expression of DNA repair genes, in order to shed light on these obscure events.

DNA repair fidelity in stem cell maintenance, health, and disease

Stem cells are a sub population of cell types that form the foundation of our body, and have the potential to replicate, replenish and repair limitlessly to maintain the tissue and organ homeostasis. Increased lifetime and frequent replication set them vulnerable for both exogenous and endogenous agents-induced DNA damage compared to normal cells. To counter these damages and preserve genetic information, stem cells have evolved with various DNA damage response and repair mechanisms. Furthermore, upon experiencing irreparable DNA damage, stem cells mostly prefer early senescence or apoptosis to avoid the accumulation of damages. However, the failure of these mechanisms leads to various diseases, including cancer. Especially, given the importance of stem cells in early development, DNA repair deficiency in stem cells leads to various disabilities like developmental delay, premature aging, sensitivity to DNA damaging agents, degenerative diseases, etc. In this review, we have summarized the recent update about how DNA repair mechanisms are regulated in stem cells and their association with disease progression and pathogenesis.

Surpassing 10 000 identified and quantified proteins in a single run by optimizing current LC-MS instrumentation and data analysis strategy

Optimization of chromatography and data analysis resulted in more than 10 000 proteins in a single shot at a validated FDR of 1% (two-species test) and revealed deep insights into the testis cancer physiology.

DNA Synthesis Is Activated in Mosquitoes and Human Monocytes During the Induction of Innate Immune Memory

Endoreplication is a cell cycle program in which cells replicate their genomes without undergoing mitosis and cytokinesis. For the normal development of many organisms (from fungi to humans) and the formation of their organs, endoreplication is indispensable. The aim of the present study was to explore whether endoreplication and DNA synthesis are relevant processes during the induction of trained innate immunity in human monocytes and in the Anopheles albimanus mosquito cell line. During the induction of trained immunity in both models, endoreplication markers were overexpressed and we observed an increase in DNA synthesis with an augmented copy number of genes essential for trained immunity. Blocking DNA synthesis prevented trained immunity from being established. Overall, these findings suggest that DNA synthesis and endoreplication are important mechanisms involved in inducing innate immune memory. They have probably been conserved throughout evolution from invertebrates to humans.

Covalent capture of OGT's active site using engineered human-E. coli chimera and intrastrand DNA cross-links

O 6-Alkylguanine DNA alkyltransferases (AGTs) are proteins found in most organisms whose role is to remove alkylation damage from the O6- and O4-positions of 2'-deoxyguanosine (dG) and thymidine (dT), respectively. Variations in active site residues between AGTs from different organisms leads to differences in repair proficiency: The human variant (hAGT) has a proclivity for removal of alkyl groups at the O6-position of guanine and the E. coli OGT protein has activity towards the O4-position of thymine. A chimeric protein (hOGT) that our laboratory has engineered with twenty of the active site residues mutated in hAGT to those found in OGT, exhibited activity towards a broader range of substrates relative to native OGT. Among the substrates that the hOGT protein was found to act upon was interstrand cross-linked DNA connected by an alkylene linkage at the O6-position of dG to the complementary strand. In the present study the activity of hOGT towards DNA containing alkylene intrastrand cross-links (IaCL) at the O6- and O4-positions respectively of dG and dT, which lack a phosphodiester linkage between the connected residues, was evaluated. The hOGT protein exhibited proficiency at removal of an alkylene linkage at the O6-atom of dG but the O4-position of dT was refractory to protein activity. The activity of the chimeric hOGT protein towards these IaCLs to prepare well defined DNA-protein cross-linked conjugates will enable mechanistic and high resolution structural studies to address the differences observed in the repair adeptness of O4-alkylated dT by the OGT protein relative to other AGT variants.

The role of gene sculptor microRNAs in human precancerous lesions

MicroRNAs (miRNAs) are small noncoding RNAs. These noncoding RNAs regulate the expression of target genes and inhibit the translation of target proteins at the post-transcriptional level. miRNAs also play an important role in human health, from the development and differentiation of cells to the occurrence and progression of disorders such as cancer, cardiovascular diseases, and neurodegenerative diseases. Precancerous lesions are lesions prior to invasive carcinomas, and carcinogenesis is a very complicated process, which is multistage and the result of multigene synergy. miRNAs exert effects as both oncogenes and tumor suppressor genes by regulating target genes involved in signaling pathways. Hence, precancerous lesions are accompanied by relevant miRNA changes. Based on the morphology of miRNAs in vivo and the specificity of miRNA, various novel miRNA analysis methods have been developed, including reverse transcription quantitative PCR, enzyme analysis, molecular beacons, and deep sequencing. For example, in the laryngeal epithelial precancerous lesions, the data demonstrate that the expression of miR-10a-5p is downregulated and miR-484 is the most abundant miRNA in hepatic precancerous lesions. In this review, we discuss the functional roles of miRNAs in human precancerous lesions.

Transcriptome profiling identifies a recurrent CRYL1-IFT88 chimeric transcript in hepatocellular carcinoma

We performed transcriptome sequencing for hepatocellular carcinoma (HCC) and adjacent non-tumorous tissues to investigate the molecular basis of HCC. Nine HCC patients were recruited and differentially expressed genes (DEGs) were identified. Candidate fusion transcripts were also identified. A total of 1943 DEGs were detected, including 690 up-regulated and 1253 down-regulated genes, and enriched in ten pathways including cell cycle, DNA replication, p53, complement and coagulation cascades, etc. Seven candidate fusion genes were detected and CRYL1-IFT88 was successfully validated in the discovery sequencing sample and another 5 tumor samples with the recurrent rate of about 9.52% (6/63). The full length of CRYL1-IFT88 was obtained by 3′ and 5′ RACE. The function of the fusion transcript is closed to CRYL1 because it contained most of domain of CRYL1. According to the bioinformatics analysis, IFT88, reported as a tumor suppressor, might be seriously depressed in the tumor cell with this fusion because the transcript structure of IFT88 was totally changed. The function depression of IFT88 caused by gene fusion CRYL1-IFT88 might be associated with tumorigenesis or development of HCC.

Implication of the Hedgehog pathway in hepatocellular carcinoma

The prognosis for patients who are diagnosed with advanced stage hepatocellular carcinoma (HCC) is poor because there are few treatment options. Recent research has focused on the identification of novel molecular entities that can be targeted to inhibit oncogenic signals that are involved in the carcinogenesis, proliferation and progression of HCC. Among all of the pathways that are involved in the development of HCC, Hedgehog (HH) signalling has demonstrated a substantial role in hepatocarcinogenesis and HCC progression. HH plays a physiological role in embryogenesis, through the induction of the differentiation of hepatocytes from endodermal progenitors. The re-activation of the HH pathway in chronic damaged liver is a mechanism of fibrotic degeneration and is implicated in various stages of HCC development. HH activation sustains the sub-population of immature liver epithelial cells that are involved in the pathogenesis of cirrhosis and HCC, and HH itself is a mediator of the alcohol-derived malignant transformation of liver cells. High levels of expression of HH protein markers in liver tumour tissues are correlated with aggressive histological and biological features and a poor clinical outcome. In vitro and in vivo inhibition models of the HH pathway confirm that HH is essential in maintaining tumour growth, metastasis and a mesenchymal phenotype.