Heterogeneous Nuclear Ribonucleoprotein hnRNP H1 Research Articles

HNRNPH1 regulates the neuroprotective cold‐shock protein RBM3 expression through poison exon exclusion

Enhanced expression of the cold‐shock protein RNA binding motif 3 (RBM3) is highly neuroprotective both in vitro and in vivo. Whilst upstream signalling pathways leading to RBM3 expression have been described, the precise molecular mechanism of RBM3 cold induction remains elusive. To identify temperature‐dependent modulators of RBM3, we performed a genome‐wide CRISPR‐Cas9 knockout screen using RBM3‐reporter human iPSC‐derived neurons. We found that RBM3 mRNA and protein levels are robustly regulated by several splicing factors, with heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) being the strongest positive regulator. Splicing analysis revealed that moderate hypothermia significantly represses the inclusion of a poison exon, which, when retained, targets the mRNA for nonsense‐mediated decay. Importantly, we show that HNRNPH1 mediates this cold‐dependent exon skipping via its thermosensitive interaction with a G‐rich motif within the poison exon. Our study provides novel mechanistic insights into the regulation of RBM3 and provides further targets for neuroprotective therapeutic strategies.

HnRNPH1 establishes Sertoli-germ cell crosstalk through cooperation with PTBP1 and AR, and is essential for male fertility in mice.

Spermatogenesis depends on the crosstalk of Sertoli cells (SCs) and germ cells. However, the gene regulatory network establishing the communications between SCs and germ cells remains unclear. Here, we report that heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) in SCs is essential for the establishment of crosstalk between SCs and germ cells. Conditional knockout of hnRNPH1 in mouse SCs leads to compromised blood-testis barrier function, delayed meiotic progression, increased germ cell apoptosis, sloughing of germ cells and, eventually, infertility of mice. Mechanistically, we discovered that hnRNPH1 could interact with the splicing regulator PTBP1 in SCs to regulate the pre-mRNA alternative splicing of the target genes functionally related to cell adhesion. Interestingly, we also found hnRNPH1 could cooperate with the androgen receptor, one of the SC-specific transcription factors, to modulate the transcription level of a group of genes associated with the cell-cell junction and EGFR pathway by directly binding to the gene promoters. Collectively, our findings reveal a crucial role for hnRNPH1 in SCs during spermatogenesis and uncover a potential molecular regulatory network involving hnRNPH1 in establishing Sertoli-germ cell crosstalk.

The E3 Ligase TRIM25 Impairs Apoptotic Cell Death in Colon Carcinoma Cells via Destabilization of Caspase-7 mRNA: A Possible Role of hnRNPH1.

Therapy resistance is still a major reason for treatment failure in colorectal cancer (CRC). Previously, we identified the E3 ubiquitin ligase TRIM25 as a novel suppressor of caspase-2 translation which contributes to the apoptosis resistance of CRC cells towards chemotherapeutic drugs. Here, we report the executioner caspase-7 as being a further target of TRIM25. The results from the gain- and loss-of-function approaches and the actinomycin D experiments indicate that TRIM25 attenuates caspase-7 expression mainly through a decrease in mRNA stability. The data from the RNA pulldown assays with immunoprecipitated TRIM25 truncations indicate a direct TRIM25 binding to caspase-7 mRNA, which is mediated by the PRY/SPRY domain, which is also known to be highly relevant for protein-protein interactions. By employing TRIM25 immunoprecipitation, we identified the heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) as a novel TRIM25 binding protein with a functional impact on caspase-7 mRNA stability. Notably, the interaction of both proteins was highly sensitive to RNase A treatment and again depended on the PRY/SPRY domain, thus indicating an indirect interaction of both proteins which is achieved through a common RNA binding. Ubiquitin affinity chromatography showed that both proteins are targets of ubiquitin modification. Functionally, the ectopic expression of caspase-7 in CRC cells caused an increase in poly ADP-ribose polymerase (PARP) cleavage concomitant with a significant increase in apoptosis. Collectively, the negative regulation of caspase-7 by TRIM25, which is possibly executed by hnRNPH1, implies a novel survival mechanism underlying the chemotherapeutic drug resistance of CRC cells. The targeting of TRIM25 could therefore offer a promising strategy for the reduction in therapy resistance in CRC patients.

The identification and verification of hub genes associated with pulmonary arterial hypertension using weighted gene co-expression network analysis

BackgroundPulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure, with complex etiology, difficult treatment and poor prognosis. The objective of this study was to investigate the potential biomarkers for PAH based on bioinformatics analysis.MethodsThe GSE117261 datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified by screening PAH patients and controls. Then the DEGs were analyzed using a Weighted Gene Co-expression Network Analysis (WGCNA) and the key modules were determined, and to further explore their potential biological functions via Gene Ontology analysis (GO), Kyoto Encyclopedia of Genes and Genomes Pathway analysis (KEGG), and Gene Set Enrichment Analysis (GSEA). Moreover, Protein–protein interaction (PPI) networks were constructed to identify hub gene candidates in the key modules. Finally, real-time quantitative polymerase chain reaction was supplied to detect the expressions of hub genes in human pulmonary arterial smooth cells treated with cobalt chloride (COCl2) which was used to mimic hypoxia.ResultsThere were 2299 DEGs identified. WGCNA indicated that yellow module was the key one correlated with PAH. GO and KEGG analysis demonstrated that genes in the yellow module were mainly enriched in ‘Pathways in cancer’. GSEA revealed that ‘HALLMARK_MYC_TARGETS_V1’ was remarkably enriched in PAH. Based on the PPI network, vascular endothelial growth factor A, proto-oncogene receptor tyrosine kinase (KIT), PNN interacting serine and arginine rich protein (PNISR) and heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) were identified as the hub genes. Additionally, the PCR indicated that the elevated expressions of PNISR and HNRNPH1 were in line with the bioinformatics analysis. ROC analysis determined that PNISR and HNRNPH1 may be potential biomarkers to provide better diagnosis of PAH.ConclusionPNISR and HNRNPH1 were potential biomarkers to diagnosis PAH. In summary, the identified DEGs, modules, pathways, and hub genes provide clues and shed light on the potential molecular mechanisms of PAH.

HnRNPH1-MTR4 complex-mediated regulation of NEAT1v2 stability is critical for IL8 expression

ABSTRACT Many long noncoding RNAs (lncRNAs) are localized in the nucleus and play important roles in various biological processes, including cell proliferation, differentiation and antiviral response. Yet, it remains unclear how some nuclear lncRNAs are turned over. Here we show that the heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) controls expression levels of NEAT1v2, a lncRNA involved in the formation of nuclear paraspeckles. hnRNPH1 associates, in an RNA-independent manner, with the RNA helicase MTR4/MTREX, an essential co-factor of the nuclear ribonucleolytic RNA exosome. hnRNPH1 localizes in nuclear speckles and depletion of hnRNPH1 enhances NEAT1v2-mediated expression of the IL8 mRNA, encoding a cytokine involved in the innate immune response. Taken together, our results indicate that the hnRNPH1-MTR4 linkage regulates IL8 expression through the degradation of NEAT1v2 RNA.

HNRNPH1 Is a Novel Regulator Of Cellular Proliferation and Disease Progression in Chronic Myeloid Leukemia.

RNA binding proteins act as essential modulators in cancers by regulating biological cellular processes. Heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1), as a key member of the heterogeneous nuclear ribonucleoproteins family, is frequently upregulated in multiple cancer cells and involved in tumorigenesis. However, the function of HNRNPH1 in chronic myeloid leukemia (CML) remains unclear. In the present study, we revealed that HNRNPH1 expression level was upregulated in CML patients and cell lines. Moreover, the higher level of HNRNPH1 was correlated with disease progression of CML. In vivo and in vitro experiments showed that knockdown of HNRNPH1 inhibited cell proliferation and promoted cell apoptosis in CML cells. Importantly, knockdown of HNRNPH1 in CML cells enhanced sensitivity to imatinib. Mechanically, HNRNPH1 could bind to the mRNA of PTPN6 and negatively regulated its expression. PTPN6 mediated the regulation between HNRNPH1 and PI3K/AKT activation. Furthermore, the HNRNPH1–PTPN6–PI3K/AKT axis played a critical role in CML tumorigenesis and development. The present study first investigated the deregulated HNRNPH1–PTPN6–PI3K/AKT axis moderated cell growth and apoptosis in CML cells, whereby targeting this pathway may be a therapeutic CML treatment.

HNRNPH1-stabilized LINC00662 promotes ovarian cancer progression by activating the GRP78/p38 pathway

Numerous studies suggest an important role for copy number alterations (CNAs) in cancer progression. However, CNAs of long intergenic noncoding RNAs (lincRNAs) in ovarian cancer (OC) and their potential functions have not been fully investigated. Here, based on analysis of The Cancer Genome Atlas (TCGA) database, we identified in this study an oncogenic lincRNA termed LINC00662 that exhibited a significant correlation between its CNA and its increased expression. LINC00662 overexpression is highly associated with malignant features in OC patients and is a prognostic indicator. LINC00662 significantly promotes OC cell proliferation and metastasis in vitro and in vivo. Mechanistically, LINC00662 is stabilized by heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1). Moreover, LINC00662 exerts oncogenic effects by interacting with glucose-regulated protein 78 (GRP78) and preventing its ubiquitination in OC cells, leading to activation of the oncogenic p38 MAPK signaling pathway. Taken together, our results define an oncogenic role for LINC00662 in OC progression mediated via GRP78/p38 signaling, with potential implications regarding therapeutic targets for OC.

The pseudogene PRELID1P6 promotes glioma progression via the hnHNPH1-Akt/mTOR axis

Research over the past decade has suggested important roles for pseudogenes in glioma. This study aimed to show that pseudogene PRELI domain-containing 1 pseudogene 6 (PRELID1P6) promotes glioma progression. Aberrant expression of genes was screened using The Cancer Genome Atlas database. We found that mRNA level of PRELID1P6 was highly upregulated in glioma and was associated with a shorter survival time. Functional studies showed that the knockdown of PRELID1P6 decreased cell proliferation, sphere formation, and clone formation ability and blocked the cell cycle transition at G0/G1, while overexpression of PRELID1P6 had the opposite effects. Mechanistically, knockdown of PRELID1P6 changed the cellular localization of heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) from nucleus to cytoplasm, which promoted ubiquitin-mediated degradation of hnRNPH1. RNA-sequence and gene set enrichment analysis suggested that knockdown of PRELID1P6 regulates the apoptosis signaling pathway. Western blotting showed that PRELID1P6 increased TRF2 expression by hnRNPH1-mediated alternative splicing effect and activated the Akt/mTOR pathway. Furthermore, Akt inhibitor MK2206 treatment reversed the oncogenic function of PRELID1P6. PRELID1P6 was also found to be negatively regulated by miR-1825. Our result showed that PRELID1P6 promotes glioma progression through the hnHNPH1-Akt/mTOR pathway. These findings shed new light on the important role of PRELID1P6 as a novel oncogene for glioma.

Abstract B25: HNRNPH1-dependent splicing of the fusion oncogene EWS-FLI1 reveals a targetable RNA G-quadruplex interaction

Abstract The primary oncogenic event in ~85% of Ewing sarcomas is a chromosomal translocation that generates a fusion gene encoding an aberrant transcription factor EWS-FLI1. In a third of EWS-FLI1 driven tumors, translocations that retain exon 8 of EWSR1 must exclude this exon to synthesize a protein-encoding mRNA. We have previously demonstrated that the heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) binds to G-rich sequences within EWSR1 exon 8 and that this binding event is required to express an in-frame EWS-FLI1 mature mRNA. G-rich nucleic acids may fold into stable tertiary structures, such as RNA guanine quadruplexes (rG4s). Our current studies are focused on the tertiary RNA structure of the G-rich regions within EWSR1 exon 8 and its role in HNRNPH1-dependent RNA processing. Here, we show that the processing of distinct EWS-FLI1 pre-mRNAs by HNRNPH1, but not other homologous family members, resembles alternative splicing of rare transcript variants of wild-type EWSR1. We demonstrate that guanine-rich sequences within EWSR1 exon 8 can fold into RNA G-quadruplex structures and that HNRNPH1 preferentially binds these RNAs when in a folded state. Critically, we also demonstrate that transfection of a single-stranded RNA oligomer corresponding to one of these G-rich sequences (rG1) reduces the expression of EWS-FLI1 mRNA and EWS-FLI1 protein and decreases its transcriptional activity. Small molecules that can displace HNRNPH1 binding may provide a therapeutic vulnerability in a subset of Ewing sarcoma. To evaluate if this protein-RNA interaction is amenable to small molecules, we performed displacement assays with HNRNPH1 protein and an EWSR1 exon 8 RNA oligomer (rG1) at varying concentrations of a G4-binding molecule, pyridostatin (PDS). We found that PDS disrupts the formation of the HNRNPH1-rG1 complex (IC50 of 7 micromolar). Furthermore, treatment with PDS selectivity inhibits the growth of Ewing sarcoma cell lines harboring EWSR1 exon 8 fusions, decreases EWS-FLI1 activity in cell-based reporter assays, and restores mRNA expression of EWS-FLI1 deregulated transcriptional targets. Our findings illustrate that modulation of the alternative splicing of EWS-FLI1 pre-mRNA is a promising strategy for future therapeutics against this fusion oncogene expressed in a third of Ewing sarcoma. Citation Format: Carla Neckles, Robert E. Boer, Nicholas Aboreden, Allison M. Cross, Robert L. Walker, Bong-Hyun Kim, Suntae Kim, John S. Schneekloth, Natasha J. Caplen. HNRNPH1-dependent splicing of the fusion oncogene EWS-FLI1 reveals a targetable RNA G-quadruplex interaction [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B25.

Abstract 4494: HNRNPH1-dependent splicing of a fusion oncogene reveals a targetable RNA G-quadruplex interaction

Abstract Ewing sarcoma (EWS) is the second most common bone tumor in children and adolescents. The primary oncogenic event in ~85% of EWS is a chromosomal translocation that generates a fusion gene encoding the aberrant transcription factor EWS-FLI1. A third of EWS-FLI1 driven tumors harbor translocations that retain exon 8 of the EWSR1 gene, and in these tumors, skipping of this exon is vital to express an in-frame EWS-FLI1 mRNA. We have shown previously that the heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) binds to G-rich sequences within EWSR1 exon 8 and facilitates the exclusion of this exon from distinct EWS-FLI1 pre-mRNAs. Guanine-rich nucleic acids may fold into stable tertiary structures, such as RNA guanine quadruplexes (rG4s). Our current studies are focused on the tertiary RNA structure of the G-rich regions within EWSR1 exon 8 and its role in HNRNPH1-dependent RNA processing. Here, we show that the processing of distinct EWS-FLI1 pre-mRNAs by HNRNPH1, but not other homologous family members, resembles alternative splicing of transcript variants of wild-type EWSR1. We demonstrate that guanine-rich sequences within EWSR1 exon 8 can fold into RNA G-quadruplex structures and that this structure favors the recruitment of HNRNPH1. Bioinformatic analysis of transcriptome-wide profiles for RNA G-quadruplexes and RNA targets of HNRNPH1 revealed sequences containing two-quartet G-quadruplex configurations are central for HNRNPH1 binding to exonic elements. Critically, we also demonstrate that the glycine-tyrosine-arginine-rich domain of HNRNPH1 is the minimal domain required for G-quadruplex recognition. Small molecules that can displace HNRNPH1 binding may provide a therapeutic vulnerability in a subset of Ewing sarcoma. To evaluate if this protein-RNA interaction is amenable to small molecules, we performed displacement assays with HNRNPH1 protein and an EWSR1 exon 8 RNA oligomer at varying concentrations of the pan-quadruplex binding molecule, pyridostatin (PDS). PDS disrupts the HNRNPH1-RNA complex with an IC50 of 7 micromolar. Furthermore, treatment with PDS selectivity inhibits the growth of EWS cells harboring EWSR1 exon 8 fusions, decreases EWS-FLI1 activity in cell-based reporter assays, and restores mRNA expression of EWS-FLI1 deregulated transcriptional targets. Our findings illustrate that splicing modulation of EWS-FLI1 pre-mRNA is a promising strategy for future therapeutics against this fusion oncogene expressed in a third of Ewing sarcoma. Citation Format: Carla Neckles, Robert Boer, Nicholas Aboreden, Robert L. Walker, Bong-Hyun Kim, Suntae Kim, John S. Schneekloth, Natasha J. Caplen. HNRNPH1-dependent splicing of a fusion oncogene reveals a targetable RNA G-quadruplex interaction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4494.

Changes in neuronal immunofluorescence in the C- versus N-terminal domains of hnRNP H following D1 dopamine receptor activation

RNA binding proteins are a diverse class of proteins that regulate all aspects of RNA metabolism. Accumulating studies indicate that heterogeneous nuclear ribonucleoproteins are associated with cellular adaptations in response to drugs of abuse. We recently mapped and validated heterogeneous nuclear ribonucleoprotein H1 (Hnrnph1) as a quantitative trait gene underlying differential behavioral sensitivity to methamphetamine. The molecular mechanisms by which hnRNP H1 alters methamphetamine behaviors are unknown but could involve pre- and/or post-synaptic changes in protein localization and function. Methamphetamine initiates post-synaptic D1 dopamine receptor signaling indirectly by binding to pre-synaptic dopamine transporters and vesicular monoamine transporters of midbrain dopaminergic neurons which triggers reverse transport and accumulation of dopamine at the synapse. Here, we examined changes in neuronal localization of hnRNP H in primary rat cortical neurons that express dopamine receptors that can be modulated by the D1 or D2 dopamine receptor agonists SKF38393 and (-)-Quinpirole HCl, respectively. Basal immunostaining of hnRNP H was localized primarily to the nucleus. D1 dopamine receptor activation induced an increase in hnRNP H nuclear immunostaining as detected by immunocytochemistry with a C-domain directed antibody containing epitope near the glycine-rich domain but not with an N-domain specific antibody. Although there was no change in hnRNP H protein in the nucleus or cytoplasm, there was a decrease in Hnrnph1 transcript following D1 receptor stimulation. Taken together, these results suggest that D1 receptor activation increases availability of the hnRNP H C-terminal epitope, which could potentially reflect changes in protein-protein interactions. Thus, D1 receptor signaling could represent a key molecular post-synaptic event linking Hnrnph1 polymorphisms to drug-induced behavior.

Serum exosomal hnRNPH1 mRNA as a novel marker for hepatocellular carcinoma.

Distinctive exosomal contents could be useful for cancer diagnosis and prognosis. However, little is known about whether serum exosomal heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) mRNA is a satisfactory biomarker for hepatocellular carcinoma (HCC). Two hundred and ninety-one participants divided into four age- and gender-matched groups, including a HCC group (n=88), a liver cirrhosis (LC) group (n=67), a chronic hepatitis B (CHB) group (n=68) and a healthy control group (n=68), were enrolled. Serum exosomal hnRNPH1 mRNA and GAPDH mRNA were measured using TaqMan real-time PCR, and the relative expression levels were calculated. Receiver operating characteristic (ROC) curves were constructed to evaluate the effectiveness of hnRNPH1 mRNA alone and in combination with α-fetoprotein (AFP) in the diagnosis of HCC. The correlation between hnRNPH1 mRNA levels and clinicopathological characteristics and overall survival (OS) in HCC was determined. The serum exosomal hnRNPH1 mRNA levels in HCC patients were remarkably higher than in the other groups (p<0.05). The hnRNPH1 mRNA discriminated HCC from CHB with an area under the ROC curve (AUC) of 0.865, with sensitivity of 85.2% and specificity of 76.5% at cut-off value of 0.670. The AUC for hnRNPH1 mRNA in combination with AFP was further improved. The exosomal hnRNPH1 mRNA levels in HCC patients were associated with the Child-Pugh classification, portal vein tumor emboli, lymph node metastasis, TNM stage and OS (p<0.05). These findings suggested that serum exosomal hnRNPH1 mRNA could be an effective marker for HCC in high HBV prevalence areas.

Abstract 2008: Ewing sarcoma cells harboring a translocation that retains EWSR1 exon 8 require HNRNPH1 to express the in-frame oncogenic fusion transcript EWS-FLI1

Abstract The primary oncogenic event in ∼85% of Ewing sarcomas is a t(11:22)(q24:q12) translocation. This translocation generates a fusion gene containing the 5’ end of the EWSR1 gene and the 3’ end of the FLI1 gene referred to as EWS-FLI1. The exact genomic breakpoints within the EWSR1 and FLI1 genes vary, but typically occur within introns and require the splicing machinery to generate an in-frame EWS-FLI1 transcript. In an estimated 40% of EWS-FLI1 driven tumors, the generation of an in-frame EWS-FLI1 fusion transcript requires alternative splicing. In particular, translocations that retain exon 8 of EWSR1 generate an out-of-frame transcript unless this exon is removed. In this study, we demonstrate that Ewing sarcoma cells harboring a genomic breakpoint that retains exon 8 of EWSR1 require HNRNPH1 to express an in-frame EWS-FLI1 mature mRNA. Using a genome-wide RNAi screen, we identified several proteins involved in RNA processing as required for the activity of EWS-FLI1, including the heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1). The role of HNRNPH1 in alternative splicing led us to hypothesize that ES cells are dependent on HNRNPH1 for the expression of the EWS-FLI1 transcript. Analysis of the expression of EWS-FLI1 following HNRNPH1 silencing in Ewing sarcoma cell lines representing different translocation breakpoints and transcript isoforms showed that only Ewing sarcoma cell lines retaining EWSR1 exon 8 at a genomic level (TC32 and SKNMC cells) are dependent on HNRNPH1 expression. Silencing of HNRNPH1 in TC32 or SKNMC cells, results in the expression of an out-of-frame EWS-FLI1 transcript that cannot express the EWS-FLI1 oncogenic transcription factor. This leads to the reversal of expression of EWS-FLI1 gene targets and cell death. Ewing sarcoma cell lines that harbor a translocation upstream of EWSR1 exon 8 (TC71 and RD-ES) exhibit none of these molecular or phenotypic changes upon HNRNPH1 silencing. We next employed an RNA pull-down and PCR strategy to identify putative binding sites for HNRNPH1 on the EWS-FLI1 pre-mRNA. This analysis showed enrichment for the binding of EWSR1 exon 8 by HNRNPH1. Towards the 3’ end of EWSR1 exon 8 we identified two G-rich sequences, a motif typically bound by HNRNPH1. To determine if HNRNPH1 binds one or both of these sites, we developed an in vitro protein-RNA-oligomer binding assay. This assay confirmed the binding of HNRNPH1 to both G-rich sites in EWSR1 exon 8. Current studies are focused on using the protein-RNA-oligomer binding assay to fully map the interaction of HNRNPH1 with sequences within EWSR1 exon 8 and understand the molecular mechanism to target it. These results demonstrate a sequence-specific, breakpoint-dependent vulnerability in Ewing sarcoma that has the potential to be exploited as a therapeutic target and suggests a novel strategy to target fusion oncogenes. Citation Format: Suntae Kim, Christiane Olivero, Guillermo O. Rangel Rivera, Nirmalya Sen, Sara Haddock, Konrad Huppi, Lee J. Helman, Patrick J. Grohar, Natasha J. Caplen. Ewing sarcoma cells harboring a translocation that retains EWSR1 exon 8 require HNRNPH1 to express the in-frame oncogenic fusion transcript EWS-FLI1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2008.

Protein and gene expression characteristics of heterogeneous nuclear ribonucleoprotein H1 in esophageal squamous cell carcinoma.

To investigate the expression characteristics of heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) mRNA and protein in cell lines and tissues of esophageal squamous cell carcinoma (ESCC). Western blotting was used to assess the expression of HNRNPH1 protein in seven ESCC cell lines and 30 paired fresh tissue specimens. The subcellular localization of HNRNPH1 was determined by immunofluorescence in ESCC cells. The RNA sequencing data from 87 patients with ESCC were obtained from the cancer genome atlas (TCGA), and the expression and clinical characteristics analysis of different transcript variants of HNRNPH1 were evaluated in this dataset. In addition, immunohistochemistry was carried out to detect the expression of HNRNPH1 protein in 125 patients. The expression of HNRNPH1 protein varied across different ESCC cell lines. It was exclusively restricted to the nucleus of the ESCC cells. There are two transcript variants of the HNRNPH1 gene. Variant 1 was constitutively expressed, and its expression did not change during tumorigenesis. In contrast, levels of variant 2 were low in non-tumorous tissues and were dramatically increased in ESCC (P = 0.0026). The high levels of variant 2 were associated with poorer differentiated tumors (P = 0.0287). Furthermore, in paired fresh tissue specimens, HNRNPH1 protein was overexpressed in 73.3% (22/30) of neoplastic tissues. HNRNPH1 was significantly upregulated in ESCC, with strong staining in 43.2% (54/125) of tumor tissues and 22.4% (28/125) of matched non-cancerous tissues (P = 0.0005). Positive HNRNPH1 expression was significantly associated with poor tumor differentiation degree (P = 0.0337). The different alternative transcript variants of HNRNPH1 exhibited different expression changes during tumorigenesis. Its mRNA and protein were overexpressed in ESCC and associated with poorer differentiation of tumor cells. These findings highlight the potential of HNRNPH1 in the therapy and diagnosis of ESCC.

Identification of hnRNPH1, NF45, and C14orf166 as Novel Host Interacting Partners of the Mature Hepatitis C Virus Core Protein

The hepatitis C virus core protein (HCVc) forms the viral nucleocapsid and is involved in viral persistence and pathogenesis, possibly by interacting with host factors to modulate viral replication and cellular functions. Here, we identified 36 cellular protein candidates by one-dimensional SDS-PAGE and LC-MS/MS-based proteomics after affinity purification with HCVc174, a matured form of HCVc from HCV-1b genotype, tagged with biotin and calmodulin-binding peptide/protein A at N- and C-termini, respectively. By pull-down and confocal imaging techniques, we confirmed that heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1), nuclear factor 45 (NF45), and C14orf166 are novel HCVc174-interacting host proteins, known to participate in mRNA metabolism, gene regulation, and microtubule organization, respectively. Unlike the other 2 proteins, NF45 interacted with HCVc174 in an RNA-dependent manner. These 3 proteins colocalized with ectopic HCVc-1b in both the cytoplasm and nucleus, which demonstrated their spatial interaction with naturally translocated HCVc174 after HCVc biogenesis. Such colocalization, however, shifted to the cytoplasm in cells with replicating virus of 1b or 2a genotype, indicating that active viral replication confined these interacting proteins in the cytoplasm. Collectively, our findings suggest that spatial interactions of hnRNPH1, NF45, and C14orf166 with HCVc174 likely modulate HCV or cellular functions during acute and chronic HCV infection.

Abstract 2712: Heterogeneous nuclear ribonucleoprotein H1 confers transcription and transactivation of androgen receptor: Implications for prostate cancer progression in African American men

Abstract Caucasian American (CA) and other ethnic minority groups. The causes of this ethnic disparity in clinical manifestation and outcome of the disease are not well understood. Here we identified, by employing a combined approach of laser capture microdissected (LCM), suppressive subtractive hybridization (SSH), and custom race-based CaP cDNA microarray on fresh specimens, selective expression of heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) in prostate tumor cells of AA men in comparison to CA men. An ethnicity-based tissue microarray (TMA) analysis revealed selective nuclear accumulation of hnRNPH1 in tumor cells compared to adjacent normal epithelium and benign prostatic hyperplasia (BPH). We also show that hnRNPH1 up-regulates transcription, physically interact with, and confers hormone-dependent (HD) and independent (HI) transactivation of androgen receptor (AR) in CaP cells. Further, our reporter, ChIP, and EMSA analyses demonstrate hnRNPH1 binds to androgen response elements (AREs) on promoter and enhancer element of PSA gene and the ligand binding domain-encoding exons D, E and H of the AR gene, suggesting it acts as a coactivator of AR in CaP cells. Interestingly, siRNA silencing of hnRNPH1caused growth arrest and enhanced cytotoxicty of Bicalutamide in AR-expressing CaP cells. These findings support a model in which hnRNP H1 is an exclusive auxiliary factor for AR to elicit androgen-specific transcriptional regulation of androgen-regulated genes and drug resistance. Given heterogeneity of CaP and that AR is implicated in androgen independent progression of CaP, the results demonstrate a previously uncharacterized mechanism for AR-hnRNPH1 axis in disease progression and hormone refractory via enhancing HD and HI mediated transcription and transactivation of AR in a subset of prostate tumor cells in AA men. The results not only reveal racial differences in the biology of CaP, but also provide, for the first time, a new frontier for the development of diagnostic, preventive, and/or targeted therapeutic strategies to circumvent disease progression in AA men. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2712.