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14 result(s) for "Dutt, Shilpee"
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HER2 borderline is a negative prognostic factor for primary malignant breast cancer
Background HER-(human epidermal growth factor receptor 2) gene amplification and protein overexpression are important predictive, prognosis markers, and therapeutic target for breast cancer, emphasizing the importance of categorizing patients into HER2 positive and negative. However, from immunohistochemistry scores, 2% patients are neither HER2 + nor -ve, but borderline called HER2B. To make informed treatment decisions of these patients, it is important to know how different this group is compared to HER-2 positive/negative. Methods We analyzed n = 104,668 breast cancer patient samples from Surveillance, Epidemiology, and End Results (SEER) database. Survival analysis was performed using open source R (Cran project R version 3.5.0) “survival” package. Hazard ratio with confidence intervals was computed using coxph function. Results Of n  = 104,668, 2239 (2.13%) patients were HER2 borderline, 87,157 (83.26%) HER2-negative, and 15,272 (14.6%) HER2-positive. The breast cancer as primary malignancy was observed in 84,944 (81.16%) patients. In primary malignant breast cancer (PMBC) patients, the hazard ratio among HER2-negative patients was significantly higher than HER2-positive patient samples (HR = 0.772, 95% CI 0.715–0.833, p  =  < .001), whereas HER2 negative status was not significantly favorable in PMBC negative patients in HER2-positive (HR = .919, 95% 0.797–1.06, p  = .248). Most importantly in PMBC patients, the HR for HER2-borderline was poor in comparison to HER2 negative (HR = 1.354, 95% CI 1.126–1.627, p  =  < .001). Conclusion This is the first report with large cohort of patient samples and significant statistical power to demonstrate that HER2 borderline represents a negative prognostic factor for PMBC. Thus providing rationale for controlled clinical trial for HER2-targeted therapies in HER2-borderline patients.
Glioblastoma recurrent cells switch between ATM and ATR pathway as an alternative strategy to survive radiation stress
Primary treatment modality for glioblastoma (GBM) post-surgery is radiation therapy. Due to increased DNA damage repair capacity of resistant residual GBM cells, recurrence is inevitable in glioblastoma and unfortunately the recurrent tumours are resistant to the conventional therapy. Here we used our previously described in vitro radiation survival model generated from primary GBM patient samples and cell lines, which recapitulates the clinical scenario of therapy resistance and relapse. Using the parent and recurrent GBM cells from these models, we show that similar to parent GBM, the recurrent GBM cells also elicit a competent DNA damage response (DDR) post irradiation. However, the use of apical DNA damage repair sensory kinase (ATM and/or ATR) is different in the recurrent cells compared to parent cells. Consistently, we demonstrate that there is a differential clonogenic response of parent and recurrent GBM cells to the ATM and ATR kinase inhibitors with recurrent samples switching between these sensory kinases for survival emphasizing on the underlying heterogeneity within and across GBM samples. Taken together, here we report that recurrent tumours utilize an alternate DDR kinase to overcome radiation induced DNA damage. Since there is no effective treatment specifically for recurred GBM patients, these findings provide a rationale for developing newer treatment option to sensitize recurrent GBM samples by detecting in clinics the ability of cells to activate a DNA damage repair kinase different from their parent counterparts.
The AID antibody diversification enzyme is regulated by protein kinase A phosphorylation
Antibodies, which are produced by B-lineage cells, consist of immunoglobulin heavy (IgH) and light (IgL) chains that have amino-terminal variable regions and carboxy-terminal constant regions. In response to antigens, B cells undergo two types of genomic alterations to increase antibody diversity. Affinity for antigen can be increased by introduction of point mutations into IgH and IgL variable regions by somatic hypermutation. In addition, antibody effector functions can be altered by changing the expressed IgH constant region exons through IgH class switch recombination (CSR) 1 , 2 , 3 . Somatic hypermutation and CSR both require the B-cell-specific activation-induced cytidine deaminase protein (AID) 4 , 5 , 6 , which initiates these reactions through its single-stranded (ss)DNA-specific cytidine deaminase activity 7 , 8 , 9 , 10 , 11 . In biochemical assays, replication protein A (RPA), a ssDNA-binding protein 12 , associates with phosphorylated AID from activated B cells and enhances AID activity on transcribed double-stranded (ds)DNA containing somatic hypermutation or CSR target sequences. This AID–RPA association, which requires phosphorylation, may provide a mechanism for allowing AID to access dsDNA targets in activated B cells 13 , 14 . Here we show that AID from B cells is phosphorylated on a consensus protein kinase A (PKA) site and that PKA is the physiological AID kinase. Thus, AID from non-lymphoid cells can be functionally phosphorylated by recombinant PKA to allow interaction with RPA and promote deamination of transcribed dsDNA substrates. Moreover, mutation of the major PKA phosphorylation site of AID preserves ssDNA deamination activity, but markedly reduces RPA-dependent dsDNA deamination activity and severely impairs the ability of AID to effect CSR in vivo . We conclude that PKA has a critical role in post-translational regulation of AID activity in B cells.
PARylation of GCN5 by PARP1 mediates its recruitment to DSBs and facilitates both HR and NHEJ Repair
Efficient DNA double strand break (DSB) repair is necessary for genomic stability and determines efficacy of DNA damaging cancer therapeutics. Spatiotemporal dynamics and post-translational modifications of repair proteins at DSBs dictate repair efficacy. Here, we identified a non-canonical function of GCN5 in regulating both HR and NHEJ repair post genotoxic stress. Mechanistically, genotoxic stress induced GCN5 recruitment to DSBs. GCN5 PARylation by PARP1 was essential for its recruitment, acetyltransferase activity and DSB repair function. Liquid chromatography-mass spectrometry (LC–MS) identified DNA-PKcs as part of GCN5 interactome. In-vitro acetyltransferase assays revealed that GCN5 acetylates DNA-PKcs at K3241 residue, a prerequisite for DNA-PKcs S2056 phosphorylation and DSB recruitment. Alongside, ChIP-qPCR revealed GCN5 mediates transcription of PRKDC via H3K27Ac acetylation in its promoter region (− 710 to − 554). Genetic perturbation of GCN5 also decreased CHEK1, NBN1, TP53BP1, POL-L transcription and abrogated ATM, BRCA1 activation. Accordingly, GCN5 loss led to persistent ɣ-H2AX foci formation, compromised in-vivo HR-NHEJ and caused GBM radio-sensitization. Importantly, PARP1 inhibition phenocopied GCN5 loss. Together, this study identifies an untraversed DSB repair function of GCN5 and provides mechanistic insights into transcriptional as well as post-translational regulation of pivotal HR-NHEJ factors. Alongside, it highlights the translational importance of PARP1-GCN5 axis in mediating GBM radio-resistance.
Aurora Kinase A and B inhibition abrogates ‘Neosis’, a non-mitotic cell division of GBM residual cells and prevents GBM recurrence
Glioblastoma (GBM) has a dismal median survival of 15 months owing to therapy resistance and inevitable recurrence. Using our cellular models of GBM radiation resistance, we had shown that GBM recurrence is due to survival and proliferation of residual disease cells enriched in multinucleated giant cells (MNGCs). However, MNGC division mechanism remained elusive. Here, using live-cell imaging we found daughter cells emerge from MNGCs by cytoplasmic pinching. Lack of DNA condensation, absence of spindle poles and acto-myosin contractile ring in dividing-MNGCs confirmed non-mitotic division of MNGCs. Furthermore, MNGCs harboured DNA damage, senescence phenotype, repeated atypical division after radiation exposure, characteristics of unconventional division called ‘Neosis’. Molecularly, WGCNA co-expression network analysis of RNA-Sequencing from parent, non-dividing MNGCs and dividing-MNGCs identified significantly high expression of aurora kinases (AurA and AurB) specifically in dividing-MNGCs. Pharmacological and genetic inhibition of aurora kinases abrogated MNGC neosis, preventing GBM recurrence in vitro and in vivo in an orthotopic GBM mouse model. Together, this study demonstrates that MNGCs divide by neosis, an atypical division mediated by AurA and AurB and identify aurora kinases as a potential molecular target to inhibit neosis and prevent GBM recurrence.
Targeted nano-delivery of chemotherapy via intranasal route suppresses in vivo glioblastoma growth and prolongs survival in the intracranial mouse model
Nanotechnology-based drug delivery platforms have shown great potential in overcoming the limitations of conventional therapy for glioblastoma (GBM). However, permeation across the blood–brain barrier (BBB), physiological complexity of the brain, and glioma targeting strategies cannot entirely meet the challenging requirements of distinctive therapeutic delivery stages. The objective of this research is to fabricate lipid nanoparticles (LNPs) for the co-delivery of paclitaxel (PTX) and miltefosine (HePc) a proapoptotic agent decorated with transferrin (Tf-PTX-LNPs) and investigate its anti-glioma activity both in vitro and in vivo orthotopic NOD/SCID GBM mouse model. The present study demonstrates the anti-glioma effect of the dual drug combination of PTX and proapoptotic HePc lipid-based transferrin receptor (TfR) targeted alternative delivery (direct nose to brain transportation) of the nanoparticulate system (Tf-PTX-LNPs, 364 ± 5 nm, −43 ± 9 mV) to overcome the O 6 -methylguanine-DNA methyltransferase induce drug-resistant for improving the effectiveness of GBM therapy. The resulting nasally targeted LNPs present good biocompatibility, stability, high BBB transcytosis through selective TfR-mediated uptake by tumor cells, and effective tumor penetration in the brain of GBM induced mice. We observed markedly enhanced anti-proliferative efficacy of the targeted LNPs in U87MG cells compared to free drug. Nasal targeted LNPs had shown significantly improved brain concentration (C max fivefold and AUC 0-24 4.9 fold) with early t max (0.5 h) than the free drug. In vivo intracranial GBM-bearing targeted LNPs treated mice exhibited significantly prolonged survival with improved anti-tumor efficacy accompanied by reduced toxicity compared to systemic Taxol ® and nasal free drug. These findings indicate that the nasal delivery of targeted synergistic nanocarrier holds great promise as a non-invasive adjuvant chemotherapy therapy of GBM. Graphical abstract
Deciphering the Diversity of Somatic Alterations and Salmonella Infection in Gallbladder Cancer by Whole Exome Sequencing
Introduction: Gallbladder cancer is relatively a rare lethal malignancy with dismal prognosis. While in India there is high incidence (3.9-8.6/1, 00,000) with majority of patients having advanced disease. Recent developments in next generation sequencing technologies have enabled the discovery of new molecular therapeutic targets in many human cancers. Objectives: Interrogate the landscape of somatic alterations in Indian gall bladder cancer using whole exome sequencing technology. Material and Methods: We interrogated the coding region of 27(10 paired and 7 unpaired) Indian gall bladder cancer samples using whole exome sequencing at an average coverage of 100X and above. We further validated the findings using an additional set of 27 FFPE samples. Results: Using a bioinformatics filtering approach, we identify a total of 5060 somatic variants found across 17 tumors consisted of 3239 missense, 1449 silent, 131 nonsense, 135 indels and 106 splice site mutations The average mutation rate considering the paired tumors is about 7.7 mutations/mb. We found TP53 (35.2%), ERBB2 (17.6%), SF3B1 (17.6%), ATM (17.6%) and AKAP11 (17.6%) mutations in more than two samples by exome sequencing analysis. Furthermore, we examined our exome sequencing data for identifying Salmonella sequences as well as presence of 143 HPV types using computation subtraction based on HPVDetector. Based on our evaluation we found association of typhoidal Salmonella strains in 11 of 26 gall bladder cancer samples and non-typhoidal Salmonella species in 12 of 26 samples, 6 samples were co-infected with both. Conclusions: The profiling of somatic alterations and identification of non typhoidal Salmonella traces may aid in changing the current treatment paradigm of gall bladder cancer.
Effect of Glucosamine Conjugate-Functionalized Liposomes on Glioma Cell and Healthy Brain: An Insight for Future Application in Brain Infusion
Conjugation of D-glucosamine with lipophilic moiety can ease its application in surface modification of liposomes. Interestingly, although D-glucosamine is safe, studies have shed light on “toxic effect” of its conjugates on cancer cells and highlighted its application in targeting glioma. However, understanding the safety of such conjugates for local delivery to the brain is unavailable. Herein, after successful synthesis of D-glucosamine conjugate (GC), the toxicity of functionalized liposome was evaluated both in vitro and in vivo. The study revealed a significant effect on cytotoxicity and apoptosis in vitro as assessed on grade IV-resistant glioma cell lines, SF268, U87MG, using MTT assay and PI staining. Additionally, this effect was not observed on normal human erythrocytes in the hemolysis assay. Furthermore, we demonstrated that GC liposomes were non-toxic to the normal brain tissues of healthy Sprague-Dawley rats. Successful functionalization yielded liposome with uniform particle size, stability, and cellular uptake. With < 10% hemolysis, all the liposomal formulations demonstrated hemato-compatibility but led to high glioma cytotoxicity. The surface density of conjugate played an important role in tumor toxicity (0.5 < 1.0 ≤ 2.0% molar ratio). PI staining revealed that compared to control cell, functionalization led 26-fold increase in induction of apoptosis in glioma cells. Absence of histological and behavioral changes along with the absence of caspase-3 in brain tissue confirmed the suitability of the system for direct infusion in the brain. Thus, this study will aid the future development of clinically useful local chemotherapeutic without “add-in” side effects.
Discovery of BEND4 as a novel single-gene prognostic marker and therapeutic target for adverse AML
Acute myeloid leukemia (AML) presents significant clinical challenges due to patient heterogeneity and variable treatment responses. Cytogenetic and mutation-based biomarkers dominate current prognostic classifications. However, many patients lack these canonical markers, and most are not therapeutic targets. Gene expression-based biomarkers, despite their clinical potential, remain underexplored. Here, we used transcriptome analyses of primary AML cohorts (n = 1338) and identified BEN domain-containing protein 4 (BEND4) as significantly overexpressed in adverse cytogenetic risk. Independent validation (n = 350) showed BEND4 was significantly overexpressed in relapse and refractory AML patients. High BEND4 expression was associated with poor overall survival, increased relapse risk, and was an independent risk factor in AML. Furthermore, in prognostic prediction, BEND4 expression outperformed mutation or gene expression-based models and a Δct threshold from RT-qPCR of <12.75 differentiated adverse risk AML patients with 91% sensitivity and 81% specificity. Functionally, BEND4 perturbation modulated chemoresistance to doxorubicin and cytarabine, apoptosis, cell cycle distribution, cellular proliferation and clonogenicity, by altering several oncogenic and inflammation-related molecular pathways. In vivo, BEND4 overexpression promoted leukemogenesis and shortened survival, whereas its suppression decreased tumor burden and improved survival. This study establishes BEND4 as a clinically relevant single gene expression-based biomarker and a potential therapeutic target in AML.
Clinical implications of MTA proteins in human cancer
Metastasis-associated gene or metastasis tumor antigen 1 (MTA1) is a new member of cancer progression-related gene family. It was first identified in rat mammary adenocarcinoma and later recognized as an important constituent of nucleosomal remodeling complex (NuRD), displaying dual regulatory functions as a co-repressor and co-activator for a large number of genes. Chromatin remodelers are ATP-dependent multi-protein chromatin modifying machines. These complexes alter the nucleosome positioning regulating the accessibility of genomic DNA to various transcription factors and thus modulate eukaryotic gene transcription. Since its identification two decades ago, MTA1 has been reported to be overexpressed in many cancers. Moreover, its overexpression has also been correlated with transformation and tumor progression. Furthermore, MTA1 has been shown to modulate the response of several tumor suppressor genes like p53 and oncogenes like c-myc. Taken together, current literature suggests that MTA proteins, especially MTA1, act as a master co-regulatory molecule involved in the carcinogenesis and progression of various malignant tumors. The primary focus of this review is to provide an overview of the MTA proteins with special emphasis on its role in cancer and use as a marker for cancer progression and potential target for therapy.