Apoptosis-Mediated Anticancer Activity of Ganoderma colossus (Agaricomycetes) Extracts in Breast Cancer Cells.

Cancer is a leading cause of death worldwide. The current cancer treatments including chemo-, radio- and immuno-therapies pose various side effects, and chances of recurrence that demand for new therapeutics to overcome the issues with existing ones. Mushrooms are considered a potential source of novel therapeutic agents. Ganoderma colossus, a non-edible wood-inhabiting mushroom, is known for certain medical properties. The present study aimed to investigate the possible anticancer activity of methanolic, ethyl acetate, and chloroform extracts of G. colossus, against MCF-7 cells and the mechanism of action(s). MTT assay and gene expression studies were carried out by following the standard protocols. The results demonstrated that among the three solvents, the ethyl acetate crude extract of the mushroom exhibited potential cytotoxic activity on MCF-7 (IC50, 17.2 ± 2.7). The DNA damage induced by the solvent extracts of G. colossus was observed by H2AX foci formation. The TP53 over-expression and flow cytometry analysis indicated that checkpoint activation followed by cell cycle arrest occurred at G1/G0 phase in response to the extract treatment. The dual acridine orange/ethidium bromide (AO/EB) staining revealed apoptosis-associated changes in the cells. Analysis of caspase 3 activations by immunophenotyping confirmed the apoptotic process in the extract-treated cells. Bcl-2 and TP53 mRNA expression data by RT-PCR disclosed the apoptosis pathway. The GC- MS spectral data of the ethyl acetate crude extract of the mushroom indicated the presence of molecules capable of inducing apoptosis. The present study warrants further studies to isolate the molecule(s) from G. colossus which may be a potential drug candidate for breast cancers.

BRCA1 interactors, RAD50 and BRIP1, as prognostic markers for triple-negative breast cancer severity.

Introduction: BRIP1 (BRCA1-interacting protein 1) is one of the major interacting partners of BRCA1, which plays an important role in repair by homologous recombination (HR). This gene is mutated in around 4% of cases of breast cancer; however, its mechanism of action is unclear. In this study, we presented the fundamental role of BRCA1 interactors BRIP1 and RAD50 in the development of differential severity in triple-negative breast cancer (TNBC) among various affected individuals. Methods: We have analyzed the expression of DNA repair-related genes in different BC cells using Real-time PCR and western blotting analysis and assessed changes in stemness property and proliferation through Immunophenotyping. We have performed cell cycle analysis to see the defect in checkpoints and also immunofluorescence assay to confirm the accumulation of gamma-H2AX and BRCA1 foci and subsequent incidence. We have performed a severity analysis using TCGA data sets for comparing the expression in MDA-MB-468 MDA-MB-231 and MCF7 cell line. Results: We showed that in some TNBC cell lines such as MDA-MB-231, the functioning of both BRCA1/TP53 is compromised. Furthermore, the sensing of DNA damage is affected. Due to less damage-sensing capability and low availability of BRCA1 at the damage sites, the repair by HR becomes inefficient, leading to more damage. Accumulation of damage sends a signal for over activation of NHEJ repair pathways. Over expressed NHEJ molecules with compromised HR and checkpoint conditions lead to higher proliferation and error-prone repair, which increases the mutation rate and corresponding tumour severity. The in-silico analysis of the TCGA datasets with gene expression in the deceased population showed a significant correlation of BRCA1 expression with overall survival (OS) in TNBCs (0.0272). The association of BRCA1 with OS became stronger with the addition of BRIP1 expression (0.000876**). Conclusion: The severity phenotypes were more in cells having compromised BRCA1-BRIP1 functioning. Since the OS is directly proportional to the extent of severity, the data analysis hints at the role of BRIP1 in controlling the severity of TNBC.

Genetic Susceptibility to Fungal Infections and Links to Human Ancestry.

Over the ages, fungi have associated with different parts of the human body and established symbiotic associations with their host. They are mostly commensal unless there are certain not so well-defined factors that trigger the conversion to a pathogenic state. Some of the factors that induce such transition can be dependent on the fungal species, environment, immunological status of the individual, and most importantly host genetics. In this review, we discuss the different aspects of how host genetics play a role in fungal infection since mutations in several genes make hosts susceptible to such infections. We evaluate how mutations modulate the key recognition between the pathogen associated molecular patterns (PAMP) and the host pattern recognition receptor (PRR) molecules. We discuss the polymorphisms in the genes of the immune system, the way it contributes toward some common fungal infections, and highlight how the immunological status of the host determines fungal recognition and cross-reactivity of some fungal antigens against human proteins that mimic them. We highlight the importance of single nucleotide polymorphisms (SNPs) that are associated with several of the receptor coding genes and discuss how it affects the signaling cascade post-infection, immune evasion, and autoimmune disorders. As part of personalized medicine, we need the application of next-generation techniques as a feasible option to incorporate an individual's susceptibility toward invasive fungal infections based on predisposing factors. Finally, we discuss the importance of studying genomic ancestry and reveal how genetic differences between the human race are linked to variation in fungal disease susceptibility.

The budding yeast protein Chl1p is required for delaying progression through G1/S phase after DNA damage.

BACKGROUND: The budding yeast protein Chl1p is a nuclear protein required for sister-chromatid cohesion, transcriptional silencing, rDNA recombination, ageing and plays an instrumental role in chromatin remodeling. This helicase is known to preserve genome integrity and spindle length in S-phase. Here we show additional roles of Chl1p at G1/S phase of the cell cycle following DNA damage. RESULTS: G1 arrested cells when exposed to DNA damage are more sensitive and show bud emergence with faster kinetics in chl1 mutants compared to wild-type cells. Also, more damage to DNA is observed in chl1 cells. The viability falls synergistically in rad24chl1 cells. The regulation of Chl1p on budding kinetics in G1 phase falls in line with Rad9p/Chk1p and shows a synergistic effect with Rad24p/Rad53p. rad9chl1 and chk1chl1 shows similar bud emergence as the single mutants chl1, rad9 and chk1. Whereas rad24chl1 and rad53chl1 shows faster bud emergence compared to the single mutants rad24, rad53 and chl1. In presence of MMS induced damage, synergistic with Rad24p indicates Chl1p's role as a checkpoint at G1/S acting parallel to damage checkpoint pathway. The faster movement of DNA content through G1/S phase and difference in phosphorylation profile of Rad53p in wild type and chl1 cells confirms the checkpoint defect in chl1 mutant cells. Further, we have also confirmed that the checkpoint defect functions in parallel to the damage checkpoint pathway of Rad24p. CONCLUSION: Chl1p shows Rad53p independent bud emergence and Rad53p dependent checkpoint activity in presence of damage. This confirms its requirement in two different pathways to maintain the G1/S arrest when cells are exposed to damaging agents. The bud emergence kinetics and DNA segregation were similar to wild type when given the same damage in nocodazole treated chl1 cells which establishes the absence of any role of Chl1p at the G2/M phase. The novelty of this paper lies in revealing the versatile role of Chl1p in checkpoints as well as repair towards regulating G1/S transition. Chl1p thus regulates the G1/S phase by affecting the G1 replication checkpoint pathway and shows an additive effect with Rad24p for Rad53p activation when damaging agents perturb the DNA. Apart from checkpoint activation, it also regulates the budding kinetics as a repair gene.

The repair gene BACH1 - a potential oncogene.

BACH1 encodes for a protein that belongs to RecQ DEAH helicase family and interacts with the BRCT repeats of BRCA1. The N-terminus of BACH1 functions in DNA metabolism as DNA-dependent ATPase and helicase. The C-terminus consists of BRCT domain, which interacts with BRCA1 and this interaction is one of the major regulator of BACH1 function. BACH1 plays important roles both in phosphorylated as well as dephosphorylated state and functions in coordination with multiple signaling molecules. The active helicase property of BACH1 is maintained by its dephosphorylated state. Imbalance between these two states enhances the development and progression of the diseased condition. Currently BACH1 is known as a tumor suppressor gene based on the presence of its clinically relevant mutations in different cancers. Through this review we have justified it to be named as an oncogene. In this review, we have explained the mechanism of how BACH1 in collaboration with BRCA1 or independently regulates various pathways like cell cycle progression, DNA replication during both normal and stressed situation, recombination and repair of damaged DNA, chromatin remodeling and epigenetic modifications. Mutation and overexpression of BACH1 are significantly found in different cancer types. This review enlists the molecular players which interact with BACH1 to regulate DNA metabolic functions, thereby revealing its potential for cancer therapeutics. We have identified the most mutated functional domain of BACH1, the hot spot for tumorigenesis, justifying it as a target molecule in different cancer types for therapeutics. BACH1 has high potentials of transforming a normal cell into a tumor cell if compromised under certain circumstances. Thus, through this review, we justify BACH1 as an oncogene along with the existing role of being a tumor suppressant.

Cross-talk between PRMT1-mediated methylation and ubiquitylation on RBM15 controls RNA splicing.

RBM15, an RNA binding protein, determines cell-fate specification of many tissues including blood. We demonstrate that RBM15 is methylated by protein arginine methyltransferase 1 (PRMT1) at residue R578, leading to its degradation via ubiquitylation by an E3 ligase (CNOT4). Overexpression of PRMT1 in acute megakaryocytic leukemia cell lines blocks megakaryocyte terminal differentiation by downregulation of RBM15 protein level. Restoring RBM15 protein level rescues megakaryocyte terminal differentiation blocked by PRMT1 overexpression. At the molecular level, RBM15 binds to pre-messenger RNA intronic regions of genes important for megakaryopoiesis such as GATA1, RUNX1, TAL1 and c-MPL. Furthermore, preferential binding of RBM15 to specific intronic regions recruits the splicing factor SF3B1 to the same sites for alternative splicing. Therefore, PRMT1 regulates alternative RNA splicing via reducing RBM15 protein concentration. Targeting PRMT1 may be a curative therapy to restore megakaryocyte differentiation for acute megakaryocytic leukemia.

Ott1 (Rbm15) regulates thrombopoietin response in hematopoietic stem cells through alternative splicing of c-Mpl.

Thrombopoietin (Thpo) signaling through the c-Mpl receptor promotes either quiescence or proliferation of hematopoietic stem cells (HSCs) in a concentration-dependent manner; however, in vivo Thpo serum levels are responsive to platelet mass rather than HSC demands, suggesting additional regulation exists. Ott1 (Rbm15), a spliceosomal component originally identified as a fusion partner in t(1;22)-associated acute megakaryocytic leukemia, is also essential for maintaining HSC quiescence under stress. Ott1 controls the alternative splicing of a dominant negative isoform, Mpl-TR, capable of inhibiting HSC engraftment and attenuating Thpo signaling. Ott1, which associates with Hdac3 and the histone methyltransferase, Setd1b, binds to both c-Mpl RNA and chromatin and regulates H4 acetylation and H3K4me3 marks. Histone deacetylase or histone methyltransferase inhibition also increases Mpl-TR levels, suggesting that Ott1 uses an underlying epigenetic mechanism to control alternative splicing of c-Mpl. Manipulation of Ott1-dependent alternative splicing may therefore provide a novel pharmacologic avenue for regulating HSC quiescence and proliferation in response to Thpo.

Functional characterization of the Saccharomyces cerevisiae protein Chl1 reveals the role of sister chromatid cohesion in the maintenance of spindle length during S-phase arrest.

BACKGROUND: Metaphase cells have short spindles for efficient bi-orientation of chromosomes. The cohesin proteins hold sister chromatids together, creating Sister Chromatid Cohesion (SCC) that helps in the maintenance of short spindle lengths in metaphase. The budding yeast protein Chl1p, which has human homologs, is required for DNA damage repair, recombination, transcriptional silencing and aging. This protein is also needed to establish SCC between sister chromatids in S-phase. RESULTS: In the present study we have further characterized Chl1p for its role in the yeast Saccharomyces cerevisiae when cells are under replication stress. We show that when DNA replication is arrested by hydroxyurea (HU), the chl1 mutation causes growth deficiency and a mild loss in cell viability. Although both mutant and wild-type cells remained arrested with undivided nuclei, mutant cells had mitotic spindles, which were about 60-80% longer than wild-type spindles. Spindle extension occurred in S-phase in the presence of an active S-phase checkpoint pathway. Further, the chl1 mutant did not show any kinetochore-related defect that could have caused spindle extension. These cells were affected in the retention of SCC in that they had only about one-fourth of the normal levels of the cohesin subunit Scc1p at centromeres, which was sufficient to bi-orient the chromosomes. The mutant cells showed defects in SCC, both during its establishment in S-phase and in its maintenance in G2. Mutants with partial and pericentromeric cohesion defects also showed spindle elongation when arrested in S-phase by HU. CONCLUSIONS: Our work shows that Chl1p is required for normal growth and cell viability in the presence of the replication block caused by HU. The absence of this protein does not, however, compromize the replication checkpoint pathway. Even though the chl1 mutation gives synthetic lethal interactions with kinetochore mutations, its absence does not affect kinetochore function; kinetochore-microtubule interactions remain unperturbed. Further, chl1 cells were found to lose SCC at centromeres in both S- and G2 phases, showing the requirement of Chl1p for the maintenance of cohesion in G2 phase of these cells. This work documents for the first time that SCC is an important determinant of spindle size in the yeast Saccharomyces cerevisiae when genotoxic agents cause S-phase arrest of cells.

The budding yeast protein Chl1p is required to preserve genome integrity upon DNA damage in S-phase.

The budding yeast protein, Chl1p, is required for sister-chromatid cohesion, transcriptional silencing, rDNA recombination and aging. In this work, we show that Chl1p is also required for viability when DNA replication is stressed, either due to mutations or if cells are treated with genotoxic agents like methylmethane sulfonate (MMS) and ultraviolet (UV) rays. The chl1 mutation caused synthetic growth defects with mutations in DNA replication genes. At semi-permissive temperatures, the double mutants grew poorly, were less viable and showed nuclear fragmentation. They were, however, not limited in their bulk DNA synthesis. When chl1 cells were treated with relatively low levels of MMS in S-phase, they lost viability. The S-phase DNA damage checkpoint pathway, however, remained active in these cells. Agarose gel electrophoresis of genomic DNA isolated from wild-type and chl1 cells, after recovery from MMS treatment, suggested that the wild-type was more proficient in the repair of DNA damage than the mutant. Our work suggests that Chl1p is required for genome integrity when cells suffer endogenously or exogenously induced DNA damage.