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MCL-1 is a high-priority target due to its dominant role in the pathogenesis and chemoresistance of cancer, yet clinical trials of MCL-1 inhibitors are revealing toxic side effects. MCL-1 biology is complex, extending beyond apoptotic regulation and confounded by its multiple isoforms, its domains of unresolved structure and function, and challenges in distinguishing noncanonical activities from the apoptotic response. We find that, in the presence or absence of an intact mitochondrial apoptotic pathway, genetic deletion or pharmacologic targeting of MCL-1 induces DNA damage and retards cell proliferation. Indeed, the cancer cell susceptibility profile of MCL-1 inhibitors better matches that of anti-proliferative than pro-apoptotic drugs, expanding their potential therapeutic applications, including synergistic combinations, but heightening therapeutic window concerns. Proteomic profiling provides a resource for mechanistic dissection and reveals the minichromosome maintenance DNA helicase as an interacting nuclear protein complex that links MCL-1 to the regulation of DNA integrity and cell-cycle progression.
Assuntos
Antineoplásicos , Proteínas Proto-Oncogênicas c-bcl-2 , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteína de Sequência 1 de Leucemia de Células Mieloides/metabolismo , Apoptose , Proteômica , Antineoplásicos/farmacologia , Dano ao DNA , Linhagem Celular TumoralRESUMO
DNA replication is a process fundamental in all living organisms in which deregulation, known as replication stress, often leads to genomic instability, a hallmark of cancer. Most malignant tumors sustain persistent proliferation and tolerate replication stress via increasing reliance to the replication stress response. So whilst replication stress induces genomic instability and tumorigenesis, the replication stress response exhibits a unique cancer-specific vulnerability that can be targeted to induce catastrophic cell proliferation. Radiation therapy, most used in cancer treatment, induces a plethora of DNA lesions that affect DNA integrity and, in-turn, DNA replication. Owing to radiation dose limitations for specific organs and tumor tissue resistance, the therapeutic window is narrow. Thus, a means to eliminate or reduce tumor radioresistance is urgently needed. Current research trends have highlighted the potential of combining replication stress regulators with radiation therapy to capitalize on the high replication stress of tumors. Here, we review the current body of evidence regarding the role of replication stress in tumor progression and discuss potential means of enhancing tumor radiosensitivity by targeting the replication stress response. We offer new insights into the possibility of combining radiation therapy with replication stress drugs for clinical use.
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Medulloblastoma (MB) is a malignant pediatric brain tumor with a poor prognosis. Post-surgical radiation and cisplatin-based chemotherapy have been a mainstay of treatment, which often leads to substantial neurocognitive impairments and morbidity, highlighting the need for a novel therapeutic target to enhance the sensitivity of MB tumors to cytotoxic therapies. We performed a comprehensive study using a cohort of 71 MB patients' samples and pediatric MB cell lines and found that MB tumors have elevated levels of nucleosome remodeling FACT (FAcilitates Chromatin Transcription) complex and DNA repair enzyme AP-endonuclease1 (APE1). FACT interacts with APE1 and facilitates recruitment and acetylation of APE1 to promote repair of radiation and cisplatin-induced DNA damage. Further, levels of FACT and acetylated APE1 both are correlate strongly with MB patients' survival. Targeting FACT complex with CBL0137 inhibits DNA repair and alters expression of a subset of genes, and significantly improves the potency of cisplatin and radiation in vitro and in MB xenograft. Notably, combination of CBL0137 and cisplatin significantly suppressed MB tumor growth in an intracranial orthotopic xenograft model. We conclude that FACT complex promotes chemo-radiation resistance in MB, and FACT inhibitor CBL0137 can be used as a chemo-radiation sensitizer to augment treatment efficacy and reduce therapy-related toxicity in high-risk pediatric patients.
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Cisplatino/administração & dosagem , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Proteínas de Ligação a DNA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Meduloblastoma/tratamento farmacológico , Fatores de Elongação da Transcrição/genética , Adolescente , Adulto , Animais , Carbazóis/administração & dosagem , Carbazóis/efeitos adversos , Criança , Pré-Escolar , Cisplatino/efeitos adversos , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/efeitos da radiação , Proteínas de Ligação a DNA/antagonistas & inibidores , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos da radiação , Xenoenxertos , Proteínas de Grupo de Alta Mobilidade/antagonistas & inibidores , Chaperonas de Histonas/genética , Humanos , Masculino , Meduloblastoma/genética , Meduloblastoma/patologia , Meduloblastoma/radioterapia , Camundongos , Fatores de Elongação da Transcrição/antagonistas & inibidores , Adulto JovemRESUMO
BACKGROUND: Single-cell sequencing enables us to better understand genetic diseases, such as cancer or autoimmune disorders, which are often affected by changes in rare cells. Currently, no existing software is aimed at identifying single nucleotide variations or micro (1-50 bp) insertions and deletions in single-cell RNA sequencing (scRNA-seq) data. Generating high-quality variant data is vital to the study of the aforementioned diseases, among others. RESULTS: In this study, we report the design and implementation of Red Panda, a novel method to accurately identify variants in scRNA-seq data. Variants were called on scRNA-seq data from human articular chondrocytes, mouse embryonic fibroblasts (MEFs), and simulated data stemming from the MEF alignments. Red Panda had the highest Positive Predictive Value at 45.0%, while other tools-FreeBayes, GATK HaplotypeCaller, GATK UnifiedGenotyper, Monovar, and Platypus-ranged from 5.8-41.53%. From the simulated data, Red Panda had the highest sensitivity at 72.44%. CONCLUSIONS: We show that our method provides a novel and improved mechanism to identify variants in scRNA-seq as compared to currently existing software. However, methods for identification of genomic variants using scRNA-seq data can be still improved.
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Fibroblastos , Polimorfismo de Nucleotídeo Único , Animais , Sequenciamento de Nucleotídeos em Larga Escala , Camundongos , Análise de Sequência de RNA , Análise de Célula Única , Software , Sequenciamento do ExomaRESUMO
Formation of G-quadruplex (G4) DNA structures in key regulatory regions in the genome has emerged as a secondary structure-based epigenetic mechanism for regulating multiple biological processes including transcription, replication, and telomere maintenance. G4 formation (folding), stabilization, and unfolding must be regulated to coordinate G4-mediated biological functions; however, how cells regulate the spatiotemporal formation of G4 structures in the genome is largely unknown. Here, we demonstrate that endogenous oxidized guanine bases in G4 sequences and the subsequent activation of the base excision repair (BER) pathway drive the spatiotemporal formation of G4 structures in the genome. Genome-wide mapping of occurrence of Apurinic/apyrimidinic (AP) site damage, binding of BER proteins, and G4 structures revealed that oxidized base-derived AP site damage and binding of OGG1 and APE1 are predominant in G4 sequences. Loss of APE1 abrogated G4 structure formation in cells, which suggests an essential role of APE1 in regulating the formation of G4 structures in the genome. Binding of APE1 to G4 sequences promotes G4 folding, and acetylation of APE1, which enhances its residence time, stabilizes G4 structures in cells. APE1 subsequently facilitates transcription factor loading to the promoter, providing mechanistic insight into the role of APE1 in G4-mediated gene expression. Our study unravels a role of endogenous oxidized DNA bases and APE1 in controlling the formation of higher-order DNA secondary structures to regulate transcription beyond its well-established role in safeguarding the genomic integrity.
Assuntos
Dano ao DNA , Reparo do DNA/fisiologia , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Quadruplex G , Células A549 , Acetilação , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Expressão Gênica , Genes myc , Genoma Humano , Guanina/química , Guanina/metabolismo , Células HCT116 , Humanos , Oxirredução , Estresse Oxidativo/genética , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas p21(ras)/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Gene fusions that contribute to oncogenicity can be explored for identifying cancer biomarkers and potential drug targets. To investigate the nature and distribution of fusion transcripts in cancer, we examined the transcriptome data of about 9,000 primary tumors from 33 different cancers in TCGA (The Cancer Genome Atlas) along with cell line data from CCLE (Cancer Cell Line Encyclopedia) using ChimeRScope, a novel fusion detection algorithm. We identified several fusions with sense (canonical, 39%) or antisense (non-canonical, 61%) transcripts recurrent across cancers. The majority of the recurrent non-canonical fusions found in our study are novel, unexplored, and exhibited highly variable profiles across cancers, with breast cancer and glioblastoma having the highest and lowest rates, respectively. Overall, 4,344 recurrent fusions were identified from TCGA in this study, of which 70% were novel. Additional analysis of 802 tumor-derived cell line transcriptome data across 20 cancers revealed significant variability in recurrent fusion profiles between primary tumors and corresponding cell lines. A subset of canonical and non-canonical fusions was validated by examining the structural variation evidence in whole-genome sequencing (WGS) data or by Sanger sequencing of fusion junctions. Several recurrent fusion genes identified in our study show promise for drug repurposing in basket trials and present opportunities for mechanistic studies.
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Fluorouracil (5-FU) remains a first-line chemotherapeutic agent for colorectal cancer. However, a subset of colorectal cancer patients who have defective mismatch-repair (dMMR) pathway show resistance to 5-FU. Here, we demonstrate that the efficacy of 5-FU in dMMR colorectal cancer cells is largely dependent on the DNA base excision repair (BER) pathway. Downregulation of APE1, a key enzyme in the BER pathway, decreases IC50 of 5-FU in dMMR colorectal cancer cells by 10-fold. Furthermore, we discover that the facilitates chromatin transcription (FACT) complex facilitates 5-FU repair in DNA via promoting the recruitment and acetylation of APE1 (AcAPE1) to damage sites in chromatin. Downregulation of FACT affects 5-FU damage repair in DNA and sensitizes dMMR colorectal cancer cells to 5-FU. Targeting the FACT complex with curaxins, a class of small molecules, significantly improves the 5-FU efficacy in dMMR colorectal cancer in vitro (â¼50-fold decrease in IC50) and in vivo xenograft models. We show that primary tumor tissues of colorectal cancer patients have higher FACT and AcAPE1 levels compared with adjacent nontumor tissues. Additionally, there is a strong clinical correlation of FACT and AcAPE1 levels with colorectal cancer patients' response to chemotherapy. Together, our study demonstrates that targeting FACT with curaxins is a promising strategy to overcome 5-FU resistance in dMMR colorectal cancer patients.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carbazóis/farmacologia , Neoplasias do Colo/tratamento farmacológico , Proteínas de Ligação a DNA/antagonistas & inibidores , Fluoruracila/farmacologia , Proteínas de Grupo de Alta Mobilidade/antagonistas & inibidores , Fatores de Elongação da Transcrição/antagonistas & inibidores , Animais , Carbazóis/administração & dosagem , Cromatina/metabolismo , Neoplasias do Colo/metabolismo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Proteínas de Ligação a DNA/metabolismo , Resistencia a Medicamentos Antineoplásicos , Fluoruracila/administração & dosagem , Células HCT116 , Células HEK293 , Proteínas de Grupo de Alta Mobilidade/metabolismo , Chaperonas de Histonas/antagonistas & inibidores , Chaperonas de Histonas/metabolismo , Humanos , Masculino , Camundongos , Camundongos Nus , Terapia de Alvo Molecular , Fatores de Elongação da Transcrição/metabolismo , Transfecção , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Medulloblastoma (MB) is a malignant pediatric brain tumor with poor prognosis. Signal transducers and activators of transcription-3 (STAT3) is constitutively activated in MB where it functions as an oncoprotein, mediating cancer progression and metastasis. Here, we have delineated the functional role of activated STAT3 in MB, by using a cell permeable STAT3-NH2 terminal domain inhibitor (S3-NTDi) that specifically perturbs the structure/function of STAT3. We have implemented several biochemical experiments using human MB tumor microarray (TMA) and pediatric MB cell lines, derived from high-risk SHH-TP53-mutated and MYC-amplified Non-WNT/SHH tumors. Treatment of MB cells with S3-NTDi leads to growth inhibition, cell cycle arrest, and apoptosis. S3-NTDi downregulated expression of STAT3 target genes, delayed migration of MB cells, attenuated epithelial-mesenchymal transition (EMT) marker expressions and reduced cancer stem-cell associated protein expressions in MB-spheres. To elucidate mechanisms, we showed that S3-NTDi induce expression of pro-apoptotic gene, C/EBP-homologous protein (CHOP), and decrease association of STAT3 to the proximal promoter of CCND1 and BCL2. Of note, S3-NTDi downregulated microRNA-21, which in turn, de-repressed Protein Inhibitor of Activated STAT3 (PIAS3), a negative regulator of STAT3 signaling pathway. Furthermore, combination therapy with S3-NTDi and cisplatin significantly decreased highly aggressive MYC-amplified MB cell growth and induced apoptosis by downregulating STAT3 regulated proliferation and anti-apoptotic gene expression. Together, our results revealed an important role of STAT3 in regulating MB pathogenesis. Disruption of this pathway with S3-NTDi, therefore, may serves as a promising candidate for targeted MB therapy by enhancing chemosensitivity of MB cells and potentially improving outcomes in high-risk patients.
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Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , MicroRNAs/genética , Chaperonas Moleculares/genética , Peptídeos/farmacologia , Proteínas Inibidoras de STAT Ativados/genética , Fator de Transcrição STAT3/genética , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Cisplatino/farmacologia , Humanos , Meduloblastoma/genética , Meduloblastoma/metabolismo , Meduloblastoma/patologia , Chaperonas Moleculares/metabolismo , Peptídeos/síntese química , Proteínas Inibidoras de STAT Ativados/metabolismo , Fator de Transcrição STAT3/antagonistas & inibidores , Fator de Transcrição STAT3/metabolismoRESUMO
The human apurinic/apyrimidinic endonuclease 1 (APE1) is a pleiotropic nuclear protein with roles in DNA base excision repair pathway as well as in regulation of transcription. Recently, the presence of extracellular plasma APE1 was reported in endotoxemic rats. However, the biological significance and the extracellular function of APE1 remain unclear. In this study, we found that monocytes secrete APE1 upon inflammatory challenges. Challenging the monocytic cells with extracellular APE1 resulted in the increased expression and secretion of the pro-inflammatory cytokine IL-6. Additionally, the extracellular APE1 treatment activated the transcription factor NF-κB, followed by its increased occupancy at the IL-6 promoter, resulting in the induction of IL-6 expression. APE1-induced IL-6 further served to elicit autocrine and paracrine cellular responses. Moreover, the extracellular IL-6 promoted the secretion of APE1, thus indicating a functional feedforward loop in this pathway. Furthermore, we show that APE1 is secreted through extracellular vesicles formation via endosomal sorting complex required for transport (ESCRT)-dependent pathway. Together, our study demonstrates a novel role of extracellular APE1 in IL-6-dependent cellular responses.
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Reparo do DNA/genética , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Regulação da Expressão Gênica , Interleucina-6/genética , Monócitos/metabolismo , NF-kappa B/metabolismo , Compostos de Anilina/farmacologia , Animais , Comunicação Autócrina/efeitos dos fármacos , Compostos de Benzilideno/farmacologia , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Vesículas Extracelulares/metabolismo , Células HCT116 , Humanos , Camundongos , NF-kappa B/genética , Comunicação Parácrina/efeitos dos fármacos , Cultura Primária de Células , Células RAW 264.7 , Células THP-1RESUMO
Increasing significance of tumor-stromal interaction in development and progression of cancer implies that signaling molecules in the tumor microenvironment (TME) might be the effective therapeutic targets for hepatocellular carcinoma (HCC). Here, the role of microRNA miR-199a-3p in the regulation of TME and development of HCC has been investigated by several in vitro and in vivo assays. Expression of miR-199a-3p was observed significantly low in HCC tissues and its overexpression remarkably inhibited in vivo tumor growth and metastasis to lung in NOD-SCID mice. In vitro restoration of miR-199a-3p expression either in endothelial cells (ECs) or in cancer cells (CACs) significantly diminished migration of ECs in co-culture assay. Again incubation of miR-199a-3p transfected ECs with either conditioned media (CM) of CACs or recombinant VEGF has reduced tube formation, in ECs and it was also dropped upon growth in CM of either anti-VEGF antibody-treated or miR-199a-3p-transfected CACs. In addition, bioinformatics and luciferase-reporter assays revealed that miR-199a-3p inhibited VEGF secretion from CACs and VEGFR1 and VEGFR2 expression on ECs and thus restricted cross talk between CACs and ECs. Again, restoration of miR-199a-3p in hepatic stellate cells (HSCs) reduced migration and invasion of CACs in co-culture assay, while it was enhanced by the overexpression of HGF suggesting miR-199a-3p has hindered HSC-CACs cross talk probably by inhibiting HGF and regulating matrix metalloproteinase MMP2, which were found as targets of miR-199a-3p subsequently by luciferase-reporter assay and gelatin zymography, respectively. Thus, these findings collectively highlight that miR-199a-3p restricts metastasis, invasion and angiogenesis in HCC and hence it may be considered as one of the powerful effective therapeutics for management of HCC patients.
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Carcinoma Hepatocelular/metabolismo , Movimento Celular , Fator de Crescimento de Hepatócito/biossíntese , Neoplasias Hepáticas/metabolismo , Metaloproteinase 2 da Matriz/biossíntese , MicroRNAs/biossíntese , Proteínas de Neoplasias/biossíntese , Neovascularização Patológica/metabolismo , RNA Neoplásico/biossíntese , Fator A de Crescimento do Endotélio Vascular/biossíntese , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/biossíntese , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/biossíntese , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Regulação Neoplásica da Expressão Gênica , Células Hep G2 , Fator de Crescimento de Hepatócito/genética , Células Endoteliais da Veia Umbilical Humana/metabolismo , Células Endoteliais da Veia Umbilical Humana/patologia , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Metaloproteinase 2 da Matriz/genética , MicroRNAs/genética , Invasividade Neoplásica , Proteínas de Neoplasias/genética , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , RNA Neoplásico/genética , Fator A de Crescimento do Endotélio Vascular/genética , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genéticaRESUMO
Apurinic/apyrimidinic (AP) sites are frequently generated in the genome by spontaneous depurination/depyrimidination or after removal of oxidized/modified bases by DNA glycosylases during the base excision repair (BER) pathway. Unrepaired AP sites are mutagenic and block DNA replication and transcription. The primary enzyme to repair AP sites in mammalian cells is AP endonuclease (APE1), which plays a key role in this repair pathway. Although overexpression of APE1 in diverse cancer types and its association with chemotherapeutic resistance are well documented, alteration of posttranslational modification of APE1 and modulation of its functions during tumorigenesis are largely unknown. Here, we show that both classical histone deacetylase HDAC1 and NAD+-dependent deacetylase SIRT1 regulate acetylation level of APE1 and acetylation of APE1 enhances its AP-endonuclease activity both in vitro and in cells. Modulation of APE1 acetylation level in cells alters AP site repair capacity of the cell extracts in vitro. Primary tumor tissues of diverse cancer types have higher level of acetylated APE1 (AcAPE1) compared to adjacent non-tumor tissue and exhibit enhanced AP site repair capacity. Importantly, in the absence of APE1 acetylation, cells accumulate AP sites in the genome and show increased sensitivity to DNA damaging agents. Together, our study demonstrates that elevation of acetylation level of APE1 in tumor could be a novel mechanism by which cells handle the elevated levels of DNA damages in response to genotoxic stress and maintain sustained proliferation.
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Dano ao DNA , Reparo do DNA , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Acetilação , Sítios de Ligação , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Histona Desacetilase 1/metabolismo , Humanos , NAD/metabolismo , Neoplasias/patologia , Ligação Proteica , Sirtuína 1/metabolismoRESUMO
Mammalian apurinic/apyrimidinic (AP) endonuclease 1 (APE1), a ubiquitous and multifunctional protein, plays an essential role in the repair of both endogenous and drug-induced DNA damages in the genome. Unlike its E.coli counterpart Xth, mammalian APE1 has a unique N-terminal domain and possesses both DNA damage repair and transcriptional regulatory functions. Although the overexpression of APE1 in diverse cancer types and the association of APE1 expression with chemotherapy resistance and poor prognosis are well documented, the cellular and molecular mechanisms that alter APE1 functions during tumorigenesis are largely unknown. Here, we show the presence of full-length APE1 and N-terminal truncated isoforms of APE1 in tumor tissue samples of various cancer types. However, primary tumor tissue has higher levels of acetylated APE1 (AcAPE1) as well as full-length APE1 compared to adjacent non-tumor tissue. We found that APE1 is proteolytically cleaved by an unknown serine protease at its N-terminus following residue lysine (Lys) Lys6 and/or Lys7 and after Lys27 and Lys31 or Lys32. Acetylation of these Lys residues in APE1 prevents this proteolysis. The N-terminal domain of APE1 and its acetylation are required for modulation of the expression of hundreds of genes. Importantly, we found that AcAPE1 is essential for sustained cell proliferation. Together, our study demonstrates that increased acetylation levels of APE1 in tumor cells inhibit the limited N-terminal proteolysis of APE1 and thereby maintain the functions of APE1 to promote tumor cells' sustained proliferation and survival.
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Proliferação de Células/fisiologia , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Regulação Neoplásica da Expressão Gênica/fisiologia , Neoplasias/metabolismo , Neoplasias/patologia , Acetilação , Humanos , Proteólise , Células Tumorais CultivadasRESUMO
BACKGROUND: The contribution of chronic hepatitis B virus (HBV) infection in the pathogenesis of hepatocellular carcinoma (HCC) through progressive stages of liver fibrosis is exacerbated by the acquisition of naturally occurring mutations in its genome. This study has investigated the prevalence of single and combo mutations in the genome of HBV-genotype D from treatment naïve Indian patients of progressive liver disease stages and assessed their impact on the disease progression to HCC. METHODS: The mutation profile was determined from the sequence analysis of the full-length HBV genome and compared with the reference HBV sequences. SPSS 16.0 and R software were used to delineate their statistical significance in predicting HCC occurrence. RESULTS: Age was identified as associated risk factor for HCC development in chronic hepatitis B (CHB) patients (p ≤ 0.01). Beyond the classical mutations in basal core promoter (BCP) (A1762T/G1764A) and precore (G1862T), persistence of progressively accumulated mutations in enhancer-I, surface, HBx and core were showed significant association to liver disease progression. BCP_T1753C, core_T147C, surface_L213I had contributed significantly in the disease progression to HCC (p < 0.05) in HBeAg positive patients whereas precore_T1858C, core_I116L, core_P130Q and preS1_S98T in HBeAg negative patients. Furthermore, the effect of individual mutation was magnified by the combination with A1762T/G1764A in HCC pathogenesis. Multivariate risk analysis had confirmed that core_P130Q [OR 20.71, 95% CI (1.64-261.77), p = 0.019] in B cell epitope and core_T147C [OR 14.58, 95% CI (1.17-181.76), p = 0.037] in CTL epitope were two independent predictors of HCC in HBeAg positive and negative patients respectively. CONCLUSIONS: Thus distinct pattern of mutations distributed across the entire HBV genome may be useful in predicting HCC in high-risk CHB patients and pattern of mutational combinations may exert greater impact on HCC risk prediction more accurately than point mutations and hence these predictors may support the existing surveillance strategies in proper management of the patients.
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Carcinoma Hepatocelular/virologia , Genoma Viral , Vírus da Hepatite B/genética , Neoplasias Hepáticas/virologia , Fígado/virologia , Mutação , Adulto , Carcinoma Hepatocelular/patologia , DNA Viral , Progressão da Doença , Feminino , Hepatite B Crônica/patologia , Hepatite B Crônica/virologia , Humanos , Fígado/patologia , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
AIMS: The impact of co-infection of several hepatitis B virus (HBV) genotypes on the clinical outcome remains controversial. This study has for the first time investigated the distribution of HBV genotypes in the serum and in the intrahepatic tissue of liver cirrhotic (LC) and hepatocellular carcinoma (HCC) patients from India. In addition, the genotype-genotype interplay and plausible mechanism of development of HCC has also been explored. METHODS: The assessment of HBV genotypes was performed by nested PCR using either surface or HBx specific primers from both the circulating virus in the serum and replicative virus that includes covalently closed circular DNA (cccDNA) and relaxed circular DNA (rcDNA) of HBV from the intrahepatic tissue. The integrated virus within the host chromosome was genotyped by Alu-PCR method. Each PCR products were cloned and sequences of five randomly selected clones were subsequently analysed. RESULTS: HBV/genotype D was detected in the serum of all LC and HCC patients whereas the sequences of the replicative HBV DNA (cccDNA and rcDNA) from the intrahepatic tissue of the same patients revealed the presence of both HBV/genotype C and D. The sequences of the integrated viruses exhibited the solo presence of HBV/genotype C in the majority of LC and HCC tissues while both HBV/genotype C and D clones were found in few patients in which HBV/genotype C was predominated. Moreover, compared to HBV/genotype D, genotype C had higher propensity to generate double strand breaks, ER stress and reactive oxygen species and it had also showed higher cellular homologous-recombination efficiency that engendered more chromosomal rearrangements, which ultimately led to development of HCC. CONCLUSIONS: Our study highlights the necessity of routine analysis of HBV genotype from the liver tissue of each chronic HBV infected patient in clinical practice to understand the disease prognosis and also to select therapeutic strategy.