Epigenomic Dysregulation in Youth Vapers: Implications for Disease Risk Assessment.

Despite the ongoing epidemic of youth vaping, the long-term health consequences of electronic cigarette use are largely unknown. We report the effects of vaping versus smoking on the oral cell methylome of healthy young vapers and smokers relative to non-users. Whereas vapers and smokers differ in number of differentially methylated regions (DMRs) (831 vs 2,863), they share striking similarities in the distribution and patterns of DNA methylation, chromatin states, transcription factor binding motifs, and pathways. There is substantial overlap in DMR-associated genes between vapers and smokers, with the shared subset of genes enriched for transcriptional regulation, signaling, tobacco use disorders, and cancer-related pathways. Of significance is the identification of a common hypermethylated DMR at the promoter of "Hypermethylated In Cancer 1" (HIC1), a tumor suppressor gene frequently silenced in smoking-related cancers. Our data support a potential link between epigenomic dysregulation in youth vapers and disease risk. These novel findings have significant implications for public health and tobacco product regulation.

Sirt7/HIC1 complex participates in hyperglycaemia-mediated EndMT via modulation of SDC1 expression in diabetic kidney disease and metabolic memory.

Diabetic kidney disease (DKD), a primary microvascular complication arising from diabetes, may result in end-stage renal disease. Epigenetic regulation of endothelial mesenchymal transition (EndMT) has been recently reported to exert function in metabolic memory and DKD. Here, we investigated the mechanism which Sirt7 modulated EndMT in human glomerular endothelial cells (HGECs) in the occurrence of metabolic memory in DKD. Lower levels of SDC1 and Sirt7 were noted in the glomeruli of both DKD patients and diabetes-induced renal injury rats, as well as in human glomerular endothelial cells (HGECs) with high blood sugar. Endothelial-to-mesenchymal transition (EndMT) was sustained despite the normalization of glycaemic control. We also found that Sirt7 overexpression associated with glucose normalization promoted the SDC1 expression and reversed EndMT in HGECs. Furthermore, the sh-Sirt7-mediated EndMT could be reversed by SDC1 overexpression. The ChIP assay revealed enrichment of Sirt7 and H3K18ac in the SDC1 promoter region. Furthermore, hypermethylated in cancer 1 (HIC1) was found to be associated with Sirt7. Overexpression of HIC1 with normoglycaemia reversed high glucose-mediated EndMT in HGECs. The knockdown of HIC1-mediated EndMT was reversed by SDC1 upregulation. In addition, the enrichment of HIC1 and Sirt7 was observed in the same promoter region of SDC1. The overexpressed Sirt7 reversed EndMT and improved renal function in insulin-treated diabetic models. This study demonstrated that the hyperglycaemia-mediated interaction between Sirt7 and HIC1 exerts a role in the metabolic memory in DKD by inactivating SDC1 transcription and mediating EndMT despite glucose normalization in HGECs.

Macrophages-derived exo-miR-4449 induced by Cryptococcus affects HUVEC permeability and promotes pyroptosis in BEAS-2B via the HIC1 pathway.

Macrophages have recently been discovered to assume a significant role in the progression of cryptococcosis. However, the potential involvement of macrophage-derived exosomes in the pathogenesis of cryptococcosis remains uncertain. In this study, we investigated the changes of microRNAs in macrophage exosomes (exo-miRNAs) in cryptococcal infections and the role of markedly altered exo-miRNAs in the modulation of Human Umbilical Vein Endothelial Cells (HUVEC) permeability and ROS accumulation and pyroptosis in Human Bronchial Epithelioid Cells (BEAS-2B). Techniques such as microarray analysis and real-time quantitative PCR were used to detect different exo-miRNAs and to screen for the most highly expressed exo-miRNAs. Then its mimics were transfected into HUVEC to study its effect on the monolayer permeability of HUVEC. Finally, the relationship between this exo-miRNAs and the ROS accumulation and pyroptosis was verified by bioinformatics analysis. The results showed that five exo-miRNAs were overexpressed and two exo-miRNAs were reduced, among which, exo-miR-4449 was expressed at the highest level. Exo-miR-4449 could be internalized by HUVEC and enhanced its monolayer permeability. Moreover, exo-miR-4449 was found to promote ROS accumulation and pyroptosis in BEAS-2B through HIC1 pathway. Thus, exo-miR-4449 plays an important role in the pathogenesis of cryptococcosis and holds promise as a significant biomarker for treatment.

Long non-coding RNA MIR17HG impedes FOSL2-mediated transcription activation of HIC1 to maintain a pro-inflammatory phenotype of microglia during intracerebral haemorrhage.

Activation and polarization of microglia play decisive roles in the progression of intracerebral haemorrhage (ICH), and lactate exposure correlates with microglia polarization. This study explores molecules influencing lactate production and microglia phenotype alteration following ICH. A murine model of ICH was induced by intracerebral injection of collagenase. The mice experienced autonomous neurological function recovery, haematoma resolution and rapid lactate production, along with a gradual increase in angiogenesis activity, neuronal recovery and an M1-to-M2 phenotype change of microglia. Galloflavin, a lactate dehydrogenase antagonist, suppressed this phenotype change and the functional recovery in mice. FOS like 2 (FOSL2) was significantly upregulated in the brain tissues from day 7 post-ICH. Overexpression of FOSL2 induced an M1-to-M2 phenotype shift in microglia and accelerated lactate production in vivo and in haemoglobin-treated microglia in vitro. Long non-coding RNA MIR17HG impeded FOSL2-mediated transcription activation of hypermethylated in cancer 1 (HIC1). MIR17HG overexpression induced pro-inflammatory activation of microglia in mice, which was blocked by further HIC1 overexpression. Overall, this study demonstrates that MIR17HG maintains a pro-inflammatory phenotype of microglia during ICH progression by negating FOSL2-mediated transcription activation of HIC1. Specific inhibition of MIR17HG or upregulation of FOSL2 or HIC1 may favour inflammation inhibition and haematoma resolution in ICH.

Development and function of smooth muscle cells is modulated by Hic1 in mouse testis.

In mammalian testis, contractile peritubular myoid cells (PMCs) regulate the transport of sperm and luminal fluid, while secreting growth factors and extracellular matrix proteins to support the spermatogonial stem cell niche. However, little is known about the role of testicular smooth muscle cells during postnatal testicular development. Here we report age-dependent expression of hypermethylated in cancer 1 (Hic1; also known as ZBTB29) in testicular smooth muscle cells, including PMCs and vascular smooth muscle cells, in the mouse. Postnatal deletion of Hic1 in smooth muscle cells led to their increased proliferation and resulted in dilatation of seminiferous tubules, with increased numbers of PMCs. These seminiferous tubules contained fewer Sertoli cells and more spermatogonia, and fibronectin was not detected in their basement membrane. The expression levels of genes encoding smooth muscle contractile proteins, Acta2 and Cnn1, were downregulated in the smooth muscle cells lacking Hic1, and the seminiferous tubules appeared to have reduced contractility. These data imply a role for Hic1 in determining the size of seminiferous tubules by regulating postnatal smooth muscle cell proliferation, subsequently affecting spermatogenesis in adulthood.

PHF20L1 mediates PAX2 expression to promote angiogenesis and liver metastasis in colorectal cancer through regulating HIC1.

Colorectal cancer (CRC) is a common cancer with poor prognosis. The research was designed to explore the role of PHF20L1 in angiogenesis and liver metastasis in CRC and discuss its molecular mechanism. Expression levels of PHF20L1, HIC1 and PAX2 in CRC tissues collected from CRC patients were detected using qRT-PCR, WB and immunohistochemical staining. CRC cells were transfected with PHF20L1, HIC1 and PAX2 overexpression or knockdown vectors and the proliferation, apoptosis, EMT and angiogenesis of the cells were determined. WB was utilized to assess protein levels of PHF20L1, HIC1, PAX2 and angiogenesis factor (ANGPT2, FGF1, PDGFA and VEGFA). The role of PHF20L1 regulating tumor formation and liver metastasis in vivo was detected as well. PHF20L1 was observed to express at a high level of CRC tissues. PHF20L1 promoted CRC cell growth, EMT and angiogenesis, and inhibited cell apoptosis. Knockdown of PHF20L1 had opposite effects on CRC cells. PHF20L1 negatively regulated HIC1 expression to promote PAX2 expression, thus promoting CRC cell progression. The in vivo results showed that PHF20L1 contributed to tumor formation and liver metastasis. PHF20L1 increases PAX2 expression to promote angiogenesis in CRC by inhibiting HIC1, therefore facilitating CRC cell EMT and liver metastasis. Our finding may provide a novel insight for CRC pathogenesis.

ZBTB7A, a miR-144-3p targeted gene, accelerates bladder cancer progression via downregulating HIC1 expression.

BACKGROUND: Zinc finger and BTB domain-containing 7A (ZBTB7A) is a member of the POK family of transcription factors that plays an oncogenic or tumor-suppressive role in different cancers depending on the type and genetic context of cancer. However, the function and molecular mechanism of ZBTB7A in bladder cancer (BC) remain elusive. METHODS: The role of ZBTB7A in bladder cancer was detected by colony formation, transwell, and tumor formation assays. The expression levels of ZBTB7A, HIC1, and miR-144-3p were analyzed by qRT-PCR and Western blot. Bioinformatics analysis and a dual-luciferase reporter assay were used to assess the effect of ZBTB7A on the promoter activity of HIC1. RESULTS: The present study revealed that knockdown of ZBTB7A suppressed BC cell growth and migration, as indicated by an approximately 50% reduction in the number of colonies and an approximately 70% reduction in the number of migrated cells. Loss of ZBTB7A inhibited tumor growth in vivo, resulting in a 75% decrease in tumor volume and an 80% decrease in tumor weight. Further mechanistic studies revealed that ZBTB7A bound to the hypermethylated in cancer 1 (HIC1) promoter and downregulated HIC1 expression, accelerating the malignant behavior of BC. Increased expression of ZBTB7A in BC tissues was negatively corrected with the expression of HIC1. Moreover, ZBTB7A was a target of miR-144-3p, which decreased ZBTB7A expression in BC. CONCLUSION: Our data demonstrate that ZBTB7A, a targeted gene of miR-144-3p, promoted tumorigenesis of BC through downregulating HIC1 expression.

The transcription factor Hypermethylated in Cancer 1 (Hic1) regulates neural crest migration via interaction with Wnt signaling.

The transcription factor Hypermethylated in Cancer 1 (HIC1) is associated with both tumorigenesis and the complex human developmental disorder Miller-Dieker Syndrome. While many studies have characterized HIC1 as a tumor suppressor, HIC1 function in development is less understood. Loss-of-function mouse alleles show embryonic lethality accompanied with developmental defects, including craniofacial abnormalities that are reminiscent of human Miller-Dieker Syndrome patients. However, the tissue origin of the defects has not been reported. In this study, we use the power of the Xenopus laevis model system to explore Hic1 function in early development. We show that hic1 mRNA is expressed throughout early Xenopus development and has a spatial distribution within the neural plate border and in migrating neural crest cells in branchial arches. Targeted manipulation of hic1 levels in the dorsal ectoderm that gives rise to neural and neural crest tissues reveals that both overexpression and knockdown of hic1 result in craniofacial defects with malformations of the craniofacial cartilages. Neural crest specification is not affected by altered hic1 levels, but migration of the cranial neural crest is impaired both in vivo and in tissue explants. Mechanistically, we find that Hic1 regulates cadherin expression profiles and canonical Wnt signaling. Taken together, these results identify Hic1 as a novel regulator of the canonical Wnt pathway during neural crest migration.

Phosphorylation of HIC1 (Hypermethylated in Cancer 1) Ser694 by ATM is essential for DNA repair.

The tumor suppressor gene HIC1 (Hypermethylated in Cancer 1) encodes a transcriptional repressor involved in the DNA-damage response. A SUMOylation increase on HIC1 Lysine314 favors the direct transcriptional repression of SIRT1 and thus the P53-dependent apoptotic response to irreparable DNA double strand breaks (DSBs). HIC1 is also essential for DSBs repair but in a SUMOylation-independent manner. Here, we show that repairable DSBs induced by a 1 h Etoposide treatment results in three specific posttranslational modifications (PTMs) of HIC1. Two of these PTMs, phosphorylation of Serine 694 and Acetylation of Lysine 623 are located in the conserved HIC1 C-terminal region located downstream of the Zinc Finger DNA-binding domain. By contrast, phosphorylation of Serine 285 found in the poorly conserved central region is unique to the human protein. We showed that Ser694 phosphorylation is mediated mainly by the PIKK kinase ATM and is essential for the DNA repair activity of HIC1 as demonstrated by the lack of efficiency of the S694A point mutant in Comet assays. Thus, our results provide the first evidence for a functional role of the conserved HIC1 C-terminal region as a novel ATM substrate that plays an essential role in the cellular HIC1-mediated cellular response to repairable DSBs.

Hypermethylated in cancer 1 (HIC1) suppresses bladder cancer progression by targeting yes-associated protein (YAP) pathway.

OBJECTIVES: Bladder cancer (BCa) is the most common malignant tumor in the urinary system. Growing evidence suggests that as a tumor suppressor gene, hypermethylated in cancer 1 (HIC1) is correlated with various malignancies in the modulation of tumor progression. This study aims to investigate the effect of HIC1 on regulating the proliferation, migration, and invasion of BCa. METHODS: Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot (WB) were used to evaluate the expression of HIC1 messenger RNA and protein in human BCa tissues and cells. Proliferation, migration and invasion assays, and flow cytometry assay were performed to assess the biological functional role of HIC1 in BCa. Co-immunoprecipitation (Co-IP) examined the protein-protein interaction. The signaling pathways involved in the mode of action of HIC1 in BCa were also investigated. RESULTS: HIC1 was found downregulated in tested samples. Cloning formation assay and cell-proliferation activity analysis showed that overexpression of HIC1 significantly inhibited the proliferation of BCa cells, while knockdown led to the opposite, namely the promotion of the proliferation. Flow cytometry assay confirmed the arrest of the cell cycle at the G1 phase with overexpression of HIC1 observed. Moreover, HIC1 inhibited migration and invasion of BCa. Co-IP showed the binding between YAP (yes-associated protein) and TEAD (TEA domain/transcription enhancer factor family members) as well as the cancerostatic activity of HIC1, partially manifested via its negative regulation of YAP signaling pathway. CONCLUSIONS: Our data unprecedently showed that HIC1 was responsible for the inhibition of proliferation, migration, and invasion of BCa via the YAP signaling pathway. These findings suggested that therapeutic strategies regulating HIC1 expression might provide effective treatments for BCa.

Tumor suppressor HIC1 is synergistically compromised by cancer-associated fibroblasts and tumor cells through the IL-6/pSTAT3 axis in breast cancer.

BACKGROUND: Interleukin-6 (IL-6) is commonly highly secreted in the breast cancer (BrCA) microenvironment and implicated in disease development. In this study, we aimed to determine the role of the IL-6/pSTAT3/HIC1 axis in the breast cancer microenvironment, including in cancer-associated fibroblasts (CAFs) and breast cancer cells. METHODS: Stromal fibroblasts from the breast cancer tissue were isolated, and the supernatants of the fibroblasts were analyzed. Recombinant human IL-6 (rhIL-6) was applied to simulate the effect of CAF-derived IL-6 to study the mechanism of HIC1 (tumor suppressor hypermethylated in cancer 1) downregulation. IL-6 was knocked down in the high IL-6-expressing BrCA cell line MDA-MB-231, which enabled the investigation of the IL-6/pSTAT3/HIC1 axis in the autocrine pathway. RESULTS: Increased IL-6 was found in the supernatant of isolated CAFs, which suppressed HIC1 expression in cancer cells and promoted BrCA cell proliferation. After stimulating the BrCA cell line SK-BR-3 (where IL-6R is highly expressed) with rhIL-6, signal transducers and activators of transcription 3 (STAT3) was found to be phosphorylated and HIC1 decreased, and a STAT3 inhibitor completely rescued HIC1 expression. Moreover, HIC1 was restored upon knocking down IL-6 expression in MDA-MB-231 cells, accompanied by a decrease in STAT3 activity. CONCLUSIONS: These findings indicate that IL-6 downregulates the tumor suppressor HIC1 and promotes BrCA development in the tumor microenvironment through paracrine or autocrine signaling.

HIC1 epigenetically represses CIITA transcription in B lymphocytes.

Differentiation of B lymphocytes into isotope-specific plasma cells represents a hallmark event in adaptive immunity. During B cell maturation, expression of the class II transactivator (CIITA) gene is down-regulated although the underlying epigenetic mechanism is not completely defined. Here we report that hypermethylated in cancer 1 (HIC1) was up-regulated in differentiating B lymphocytes paralleling CIITA repression. Over-expression of HIC1 directly repressed endogenous CIITA transcription in B cells. Reporter assay and chromatin immunoprecipitation (ChIP) assay confirmed that HIC1 bound to the proximal CIITA type III promoter (-545/-113); mutation of a conserved HIC1 site within this region abrogated CIITA trans-repression. More important, depletion of HIC1 with small interfering RNA (siRNA) restored CIITA expression in differentiating B cells. Mechanistically, HIC1 preferentially interacted with and recruited DNMT1 and DNMT3b to the CIITA promoter to synergistically repress CIITA transcription. On the contrary, silencing of DNMT1/DNMT3b or inhibition of DNMT activity with 5-aza-dC attenuated CIITA trans-repression. Therefore, our data identify HIC1 as a novel factor involved in B cell differentiation acting as an epigenetic repressor of CIITA transcription.

Tandem repeat variation near the HIC1 (hypermethylated in cancer 1) promoter predicts outcome of oxaliplatin-based chemotherapy in patients with metastatic colorectal cancer.

BACKGROUND: The hypermethylated in cancer 1/sirtuin 1 (HIC1/SIRT1) axis plays an important role in regulating the nucleotide excision repair pathway, which is the main oxaliplatin-induced damage-repair system. On the basis of prior evidence that the variable number of tandem repeat (VNTR) sequence located near the promoter lesion of HIC1 is associated with HIC1 gene expression, the authors tested the hypothesis that this VNTR is associated with clinical outcome in patients with metastatic colorectal cancer who receive oxaliplatin-based chemotherapy. METHODS: Four independent cohorts were tested. Patients who received oxaliplatin-based chemotherapy served as the training cohort (n = 218), and those who received treatment without oxaliplatin served as the control cohort (n = 215). Two cohorts of patients who received oxaliplatin-based chemotherapy were used for validation studies (n = 176 and n = 73). The VNTR sequence near HIC1 was analyzed by polymerase chain reaction analysis and gel electrophoresis and was tested for associations with the response rate, progression-free survival, and overall survival. RESULTS: In the training cohort, patients who harbored at least 5 tandem repeats (TRs) in both alleles had a significantly shorter PFS compared with those who had fewer than 4 TRs in at least 1 allele (9.5 vs 11.6 months; hazard ratio, 1.93; P = .012), and these findings remained statistically significant after multivariate analysis (hazard ratio, 2.00; 95% confidence interval, 1.13-3.54; P = .018). This preliminary association was confirmed in the validation cohort, and patients who had at least 5 TRs in both alleles had a worse PFS compared with the other cohort (7.9 vs 9.8 months; hazard ratio, 1.85; P = .044). CONCLUSIONS: The current findings suggest that the VNTR sequence near HIC1 could be a predictive marker for oxaliplatin-based chemotherapy in patients with metastatic colorectal cancer. Cancer 2017;123:4506-14. © 2017 American Cancer Society.

HIC1 modulates uveal melanoma progression by activating lncRNA-numb.

Uveal melanoma (UM) is the most common primary intraocular cancer in adults. Although the diagnosis modality of primary UM was improved significantly, there are currently no effective therapies for metastatic UM. Hypermethylated in cancer 1 (HIC1) is frequently deleted or epigenetically silenced in various human cancers. However, the role and mechanism of HIC1 in UM is still unclear. In this study, we found that HIC1 acted as a tumor suppressor and that its expression was downregulated in UM. Functional studies demonstrated that ectopic expression of HIC1 in UM cells inhibited cell proliferation and invasion. Moreover, through long non-coding RNA (lncRNA) microarray and real-time PCR, we found that expression of lncRNA-numb was activated by HIC1 in UM. The results provide evidence that lncRNA-numb is a newly proposed tumor suppressor that is involved in HIC1-induced phenotypes. Taken together, our studies of UM reveal a critical role of HIC1 in the regulation of tumorigenesis, at least partly through its downstream target, lncRNA-numb, and provide a potential therapeutic target for UM.

Comprehensive silencing of target-sharing microRNAs is a mechanism for SIRT1 overexpression in cancer.

Overexpression of SIRT1 is frequently observed in various types of cancers, suggesting its potential role in malignancies. However, the molecular basis of how SIRT1 is elevated in cancer is less understood. Here we show that cancer-related SIRT1 overexpression is due to evasion of Sirt1 mRNA from repression by a group of Sirt1-targeting microRNAs (miRNAs) that might be robustly silenced in cancer. Our comprehensive library-based screening and subsequent miRNA gene profiling revealed a housekeeping gene-like broad expression pattern and strong CpG island-association of the Sirt1-targeting miRNA genes. This suggests aberrant CpG DNA methylation as the mechanistic background for malignant SIRT1 elevation. Our work also provides an example where epigenetic mechanisms cause the group-wide regulation of miRNAs sharing a common key target.

Single-cell analysis of mesenchymal cells in permeable neural vasculature reveals novel diverse subpopulations of fibroblasts.

BACKGROUND: In the choroid plexus and pituitary gland, vasculature is known to have a permeable, fenestrated phenotype which allows for the free passage of molecules in contrast to the blood brain barrier observed in the rest of the CNS. The endothelium of these compartments, along with secretory, neural-lineage cells (choroid epithelium and pituitary endocrine cells) have been studied in detail, but less attention has been given to the perivascular mesenchymal cells of these compartments. METHODS: The Hic1CreERT2 Rosa26LSL-TdTomato mouse model was used in conjunction with a PdgfraH2B-EGFP mouse model to examine mesenchymal cells, which can be subdivided into Pdgfra+ fibroblasts and Pdgfra- pericytes within the choroid plexus (CP) and pituitary gland (PG), by histological, immunofluorescence staining and single-cell RNA-sequencing analyses. RESULTS: We found that both CP and PG possess substantial populations of distinct Hic1+ mesenchymal cells, including an abundance of Pdgfra+ fibroblasts. Within the pituitary, we identified distinct subpopulations of Hic1+ fibroblasts in the glandular anterior pituitary and the neurosecretory posterior pituitary. We also identified multiple distinct markers of CP, PG, and the meningeal mesenchymal compartment, including alkaline phosphatase, indole-n-methyltransferase and CD34. CONCLUSIONS: Novel, distinct subpopulations of mesenchymal cells can be found in permeable vascular interfaces, including the CP, PG, and meninges, and make distinct contributions to both organs through the production of structural proteins, enzymes, transporters, and trophic molecules.

Computational Analysis of Single Nucleotide Polymorphisms in Human HIC1 Gene.

Background A putative tumor suppressor gene called HIC1 (hypermethylated in cancer) is situated at 17p13.3, a locus where the allelic loss occurs often in human malignancies, including breast cancer. Hypermethylated in cancer 1 protein is a protein that in humans is encoded by the HIC1 gene and it's a Homo sapiens (Human). This gene functions as a growth regulatory and tumor repressor gene. The molecular function of HIC1 gene includes DNA-binding transcription factor activity, sequence-specific DNA binding, DNA binding, histone deacetylase binding, protein binding, metal ion binding, nucleic acid binding, DNA-binding transcription repressor activity, RNA polymerase II-specific, DNA-binding transcription factor activity, RNA polymerase II-specific. The biological process of HIC1 gene includes multicellular organism development, negative regulation of Wnt signaling pathway, positive regulation of DNA damage response, signal transduction by p53 class mediator regulation of transcription, DNA-templated, negative regulation of transcription by RNA polymerase II, Wnt signaling pathway, transcription, DNA-templated, intrinsic apoptotic signaling pathway in response to DNA damage, cellular response to DNA damage stimulus. The study aimed to predict the stability and structure of the protein that will arise from single nucleotide polymorphisms (SNPs) in the human HIC1 gene. Methodology To investigate the possible negative effects associated with these SNPs, bioinformatic analysis is typically essential. The following tools were employed for forecasting harmful SNPs: scale-invariant feature transform (SIFT), Protein Analysis Through Evolutionary Relationships (PANTHER), nonsynonymous SNP by Protein Variation Effect Analyzer (PROVEAN), and nonsynonymous SNP by Single Nucleotide Polymorphism Annotation Platform (SNAP). Results The present study identified a total of 36 SNPs using the SIFT approach, which were shown to have functional significance. Twenty-six were determined to be tolerable, whereas 10 were shown to be detrimental. Out of 20 SNPs, seven (P370A, P646S, R654P, A476T, S400S, D666N, D7V) SNPs were predicted as "Possibly damaging" and seven (L9F, G468R, G490R, L482R, S12W, G489D, S12P) were identified as "probably benign", and six (R725G, G620S, A56V, E463D, D394N, L338V) were identified as "probably damaging" according to the predictions made by PANTHER tools. The majority of the pixels on the strip were red, indicating that the gene changes may have dangerous consequences. These results highlight the need for more research to fully comprehend how these mutations affect the hic1 protein's function, which is essential for the emergence of different types of cancer. Conclusion The current research has provided us with essential information about how SNPs might be used as a diagnostic marker for cancer, given that SNPs may be candidates for cellular changes caused by mutations linked to cancer.

The Reelin receptors ApoER2 and VLDLR are direct target genes of HIC1 (Hypermethylated In Cancer 1).

The tumor suppressor gene HIC1 (Hypermethylated In Cancer 1) is located in 17p13.3 a region frequently hypermethylated or deleted in tumors and in a contiguous-gene syndrome, the Miller-Dieker syndrome which includes classical lissencephaly (smooth brain) and severe developmental defects. HIC1 encodes a transcriptional repressor involved in the regulation of growth control, DNA damage response and cell migration properties. We previously demonstrated that the membrane-associated G-protein-coupled receptors CXCR7, ADRB2 and the tyrosine kinase receptor EphA2 are direct target genes of HIC1. Here we show that ectopic expression of HIC1 in U2OS and MDA-MB-231 cell lines decreases expression of the ApoER2 and VLDLR genes, encoding two canonical tyrosine kinase receptors for Reelin. Conversely, knock-down of endogenous HIC1 in BJ-Tert normal human fibroblasts through RNA interference results in the up-regulation of these two Reelin receptors. Finally, through chromatin immunoprecipitation (ChIP) in BJ-Tert fibroblasts, we demonstrate that HIC1 is a direct transcriptional repressor of ApoER2 and VLDLR. These data provide evidence that HIC1 is a new regulator of the Reelin pathway which is essential for the proper migration of neuronal precursors during the normal development of the cerebral cortex, of Purkinje cells in the cerebellum and of mammary epithelial cells. Deregulation of this pathway through HIC1 inactivation or deletion may contribute to its role in tumor promotion. Moreover, HIC1, through the direct transcriptional repression of ATOH1 and the Reelin receptors ApoER2 and VLDLR, could play an essential role in normal cerebellar development.

Luteolin exhibits synergistic therapeutic efficacy with erastin to induce ferroptosis in colon cancer cells through the HIC1-mediated inhibition of GPX4 expression.

Colon cancer continues to be a prevalent gastrointestinal malignancy with a bleak prognosis. The induction of ferroptosis, a new form of regulated cell death, has emerged as a potentially effective strategy for the treatment of colon cancer. However, numerous colon cancer cells display resistance to ferroptosis induced by erastin, a well-established ferroptosis inducer. Finding drugs that can enhance the susceptibility of colon cancer cells to erastin is of utmost importance. This study aimed to examine the synergistic therapeutic impact of combining erastin with a bioactive flavonoid compound luteolin on the ferroptosis-mediated suppression of colon cancer. Human colon cancer HCT116 and SW480 cells were used for the in vitro studies and a xenograft of colon cancer model in BALB/c nude mice was established for the in vivo experiments. The results showed that combinative treatment of luteolin and erastin effectively inhibited the viability and proliferation of colon cancer cells. Luteolin and erastin cotreatment synergistically induced ferroptosis, concomitant with a reduction in glutathione and an elevation in lipid peroxides. In vivo, combinative treatment of luteolin and erastin exhibited a pronounced therapeutic effect on xenografts of colon cancer, characterized by a significant induction of ferroptosis. Mechanistically, luteolin in combination with erastin synergistically reduced the expression of glutathione peroxidase 4 (GPX4), an antioxidase overexpressed in colon cancer cells. Furthermore, luteolin and erastin cotreatment significantly upregulated the expression of hypermethylated in cancer 1 gene (HIC1), a transcriptional repressor also recognized as a tumor suppressor. HIC1 overexpression notably augmented the suppression of GPX4 expression and facilitated ferroptotic cell death. In contrast, HIC1 silencing attenuated the inhibition of GPX4 expression and eliminated the ferroptosis. Conclusively, these results clearly demonstrated that luteolin acts synergistically with erastin and renders colon cancer cells vulnerable to ferroptosis through the HIC1-mediated inhibition of GPX4 expression, which may act as a promising therapeutic strategy.

HIC1 interacts with FOXP3 multi protein complex: Novel pleiotropic mechanisms to regulate human regulatory T cell differentiation and function.

Transcriptional repressor, hypermethylated in cancer 1 (HIC1) participates in a range of important biological processes, such as tumor repression, immune suppression, embryonic development and epigenetic gene regulation. Further to these, we previously demonstrated that HIC1 provides a significant contribution to the function and development of regulatory T (Treg) cells. However, the mechanism by which it regulates these processes was not apparent. To address this question, we used affinity-purification mass spectrometry to characterize the HIC1 interactome in human Treg cells. Altogether 61 high-confidence interactors were identified, including IKZF3, which is a key transcription factor in the development of Treg cells. The biological processes associated with these interacting proteins include protein transport, mRNA processing, non-coding (ncRNA) transcription and RNA metabolism. The results revealed that HIC1 is part of a FOXP3-RUNX1-CBFB protein complex that regulates Treg signature genes thus improving our understanding of HIC1 function during early Treg cell differentiation.