BACKGROUND: Osteoporosis (OP) is a prevalent disease associated with age, and one of the primary pathologies is the defect of osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). This study aimed to elucidate whether Nuclear Receptor Binding SET Domain Protein 2 (NSD2) transcriptionally regulates osteogenic differentiation of BMSCs in osteoporosis.
METHODS: Identification of human BMSCs (hBMSCs) in vitro was measured by flow cytometry. Osteogenesis of hBMSCs in vitro was measured by Alizarin Red and Alkaline Phosphatase staining. The protein levels of H3K36me1/2/3, NSD2, and Hoxa2 were measured by western blotting. The mRNA levels of NSD2, Runx2, and BSP were measured by qPCR. The role of NSD2 in the osteogenic differentiation of BMSCs was further identified by silencing NSD2 via shRNA or overexpression of NSD2 via lentivirus transfection. The interactions of NSD2, H3K36me2 and Hoxa2 were identified via chromatin immunoprecipitation (ChIP). Luciferase reporting analysis was employed to confirm that NSD2 regulated the transcriptional activity of Hoxa2. Ovariectomized (OVX) was performed on mice to construct osteoporosis (OP) model. Subsequently, the bone mass was assessed by micro computed tomography (micro-CT) scan.
RESULTS: During the osteogenesis of OP-derived hBMSCs, the levels of NSD2 and H3K36me2 significantly increased in 14 days of osteogenic induction. Inhibition of NSD2 via shRNA increased the RUNX2 and BSP expression of hBMSCs, while overexpression of NSD2 decreased RUNX2 and BSP expression of hBMSCs. ChIP analysis indicated NSD2-mediated H3K36me2 reduced the osteogenic differentiation of hBMSCs by regulating the osteogenic inhibitor Hoxa2. Accordingly, inhibition of NSD2 in vivo via tail vein injection of LV-shNSD2 lentivirus greatly alleviated OVX-induced osteoporosis in mice.
CONCLUSIONS: We demonstrated that NSD2 inhibited the osteogenic differentiation in hBMSCs by transcriptionally downregulating Hoxa2 via H3K36me2 dimethylation. Inhibition of NSD2 effectively attenuated bone loss in murine osteoporosis and NSD2 is a promising target for clinical treatment of osteoporosis.

Cranial neural crest cells (NCCs) are critical for craniofacial development. The administration of valproic acid (VPA) to pregnant females causes craniofacial malformations in offspring. However, the in vivo influence of VPA on mammalian cranial NCCs remains unclear. In this study, we aimed to elucidate the developmental stage-specific effect of VPA on cranial NCCs through the administration of a single dose of VPA to pregnant rat females immediately prior to the formation of the cranial neural crest (NC). We performed whole-mount immunohistochemistry or in situ hybridization to examine localization changes of gene transcripts associated with the epithelial-mesenchymal transition of the cranial NC (i.e., cranial NCC formation) and cranial NCC migration. The results showed that Hoxa2 mRNA was abnormally detected and Sox9 mRNA expression was decreased in the midbrain-rhombomere (R) 1/2 NC, which forms cranial NCCs that migrate to the frontonasal mass (FNM) and branchial arch (BA) 1, through VPA administration, thus reducing the formation of SNAI2-positive NCCs. Hoxa2-positive NCCs were detected normally in BA2 and abnormally in FNM and BA1, which are normally Hox-free, implying VPA-induced abnormal cranial NCC migration. In vitro verification experiments using the whole embryo culture system revealed that midbrain-R4 NCC migration was abnormal. These results indicate that VPA reduces the formation/delamination of the midbrain-R1/2 NCCs in a developmental stage-specific manner and subsequently causes the abnormal migration of R4 NCCs, which suggests that the abnormal formation and migration of cranial NCCs contribute to the inhibition of axonal elongation in the trigeminal nerve and a reduction in head size.

BACKGROUND: Long non-coding RNAs (lncRNAs) are increasingly observed as regulatory factors for the initiation and progression of varying kinds of cancers. However, studies on lncRNAs in non-small cell lung cancer (NSCLC) progression are currently lacking.
OBJECTIVE: We intended to determine the role of lncRNA LINC00472 and its downstream regulatory mechanism in NSCLC, thus providing novel ideas for targeted therapies for NSCLC.
METHODS: The target signaling axis comprising the lncRNA/microRNA/mRNA was identified through bioinformatics analysis. Subcellular localization of LINC00472 was assessed with fluorescence in situ hybridization (FISH). Cellular function experiments were conducted to examine the proliferation, migration, invasion, and apoptosis of NSCLC cells, and dual-luciferase and RNA binding protein immunoprecipitation assays were performed to validate the binding relationship. Quantitative real-time polymerase chain reaction (qPCR) and western blot were utilized to assess the expression levels of the investigated gene and protein, respectively.
RESULTS: The LINC00472 expression was markedly decreased in NSCLC tissues and cells. The FISH, combined with nuclear-cytoplasm separation assay, demonstrated that LINC00472 was mainly located in the cytoplasm. The overexpression of LINC00472 restrained proliferation and metastasis of NSCLC in vitro. The LINC00472 could target and repress miR-1275 level, and overexpression of LINC00472 reduced the miR-1275-dependent malignant cell phenotype in NSCLC. Further study revealed that HOXA2 was a downstream target of miR-1275 and was negatively modulated by miR-1275. Rescue assays exhibited that the overexpression of miR-1275 or inhibition of HOXA2 reversed the impact of LINC00472 overexpression on the malignant progression of NSCLC cells. The LINC00472 repressed the epithelial-mesenchymal transition (EMT) of NSCLC cells through miR-1275/HOXA2.
CONCLUSIONS: The LINC00472 functioned as a competing endogenous RNA to modulate HOXA2 level by sponging miR-1275 in NSCLC. Simultaneously, the LINC00472/miR-1275/HOXA2 axis may be a possible therapeutic target and biomarker for NSCLC.

Providing appropriate positional identity and patterning information to distinct rostrocaudal subpopulations of cranial neural crest cells (CNCCs) is central to vertebrate craniofacial morphogenesis. Hox genes are not expressed in frontonasal and first pharyngeal arch (PA1) CNCCs, whereas a single Hox gene, Hoxa2, is necessary to provide patterning information to second pharyngeal arch (PA2) CNCCs. In frog, chick and mouse embryos, ectopic expression of Hoxa2 in Hox-negative CNCCs induced hypoplastic phenotypes of CNCC derivatives of variable severity, associated or not with homeotic transformation of a subset of PA1 structures into a PA2-like identity. Whether these different morphological outcomes are directly related to distinct Hoxa2 overexpression levels is unknown. To address this issue, we selectively induced Hoxa2 overexpression in mouse CNCCs, using a panel of mouse lines expressing different Hoxa2 ectopic expression levels, including a newly generated Hoxa2 knocked-in mouse line. While ectopic Hoxa2 expression at only 60% of its physiological levels was sufficient for pinna duplication, ectopic Hoxa2 expression at 100% of its normal level was required for complete homeotic repatterning of a subset of PA1 skeletal elements into a duplicated set of PA2-like elements. On the other hand, ectopic Hoxa2 overexpression at non-physiological levels (200% of normal levels) led to an almost complete loss of craniofacial skeletal structures. Moreover, ectopic Hoxa5 overexpression in CNCCs, while also resulting in severe craniofacial defects, did not induce homeotic changes of PA1-derived CNCCs, indicating Hoxa2 specificity in repatterning a subset of Hox-negative CNCCs. These results reconcile some discrepancies in previously published experiments and indicate that distinct subpopulations of CNCCs are differentially sensitive to ectopic levels of Hox expression.

HOX genes are important regulatory genes patterning head formation, including development of the ear. Microtia is a congenital ear anomaly characterized by lacking all or part of the structures of the outer ear. To date, only four HOXA2 mutations were reported in families with autosomal-recessive or dominant microtia, with or without hearing impairment. More identified mutations are needed to confirm the correlation between genotype and phenotype. Here, we collect two Chinese families with non-syndromic bilateral microtia. Next generation sequencing identified two heterozygous nonsense HOXA2 mutations, one in each family. One mutation (c.637A > T, p.Lys213*) is newly reported, while the other one (c.703C > T,p.Gln235*) is consistent with a previous report. In mouse, Hoxa2 can bind to a long-range enhancer and regulate expression of the Hmx1 gene, which is a crucial transcription factor in eye and ear development. Using dual luciferase reporter assays, we showed that both HOXA2 mutations have impaired activation of the long-range enhancer of HMX1. In the present study, we report the first two bilateral non-syndromic microtia cases with HOXA2 mutations of Chinese origin and identify a novel mutation. Our results also provide molecular insights about how these nonsense HOXA2 mutations could affect the activation of its downstream target HMX1 by interacting with the long-range enhancer.

In recent years, studies have revealed HOXA2 as a new oncogene, but its function is unknown in gliomas. We aimed to reveal the relationship between HOXA2 and glioma based on the Chinese Glioma Genome Atlas(CGGA) and the cancer genome atlas (TCGA). HOXA2 expression data and clinically relevant information of glioma patients were obtained from the CGGA and TCGA containing 1447 glioma tissues and five non-tumor brain tissues. The Wilcox or Kruskal tests were used to detect the correlation between the HOXA2 expression level and clinical data of glioma patients. the Kaplan-Meier method were used to examine the relationship between HOXA2 and overall patient survival. Gene set enrichment analysis (GSEA) was conducted to indirectly reveal the signaling pathways involved in HOXA2, and RT-PCR was used to detect HOXA2 expression in gliomas and non-tumor brain tissues. High HOXA2 expression was found to be positively correlated with clinical grade, histological type, age, and tumor recurrence, but negatively correlated with 1p19 codeletion and isocitrate dehydrogenase mutation status.RT-PCR results showed that HOXA2 expression levels were significantly higher in tumor tissues than in non-tumor brain tissues. GSEA showed that HOXA2 promoted the activation of the activation of the JAK-STAT-signaling pathway, focal adhesion, cell-adhesion-molecules-CAMS pathway, cytosolic DNA sensing pathway, and natural killer cell-mediated cytotoxicity. This study revealed for the first time that the novel oncogene,HOXA2, leads to poor prognosis in gliomas, and can be used as a biomarker for the diagnosis and treatment of gliomas.

Dental follicle (DF) can develop into periodontal tissues including periodontal ligament, cementum, and alveolar bone. Possessing superior pluripotency and osteogenic capacity, dental follicle stem cells (DFSCs) have become a promising stem cell source for bone regeneration and periodontal engineering. However, the mechanisms underlying DFSCs-mediated osteogenesis remain elusive. Our previous long noncoding RNA (lncRNA) microarray revealed that lncRNA HOTAIRM1 was significantly higher expressed in human DFSCs (hDFSCs) compared with human periodontal ligament stem cells (hPDLSCs). lncRNA HOTAIRM1, an antisense transcript of the HOXA1/2 intergenic region, can epigenetically regulate proximal and distant HOXA genes through histone and DNA methylation. HOXA2, a target of HOTAIRM1, is crucial for cranial neural crest morphogenesis, branchial arches development, and osteogenesis. However, the roles of both HOTAIRM1 and HOXA2 in odontogenic stem cells remain unknown. Here, we investigated the functions and regulatory mechanisms of these two genes in hDFSCs. Both genes were confirmed highly expressed in hDFSCs compared with hPDLSCs, and they displayed similar expression patterns in the DF and surrounding periodontium during mice tooth morphogenesis. Knockdown of either HOTAIRM1 or HOXA2 inhibited osteogenic differentiation of hDFSCs, while overexpressed HOTAIRM1 inhibited hDFSCs proliferation and promoted osteogenesis. Furthermore, HOTAIRM1 inhibited both overall DNMT1 expression and DNMT1 enrichment on HOXA2 promoter, mechanically binding to the CpG islands of the HOXA2 promoter region, leading to hypomethylation and HOXA2 induction. These findings suggested that HOTAIRM1 promoted the osteogenesis of hDFSCs by epigenetically regulating HOXA2 via DNMT1. Taken together, HOTARIM1 and HOXA2 exerted pivotal functions in hDFSCs, and the regulatory mechanism of HOTARIM1 within the HOXA cluster was uncovered.

Research on DNA methylation offers great potential for the identification of biomarkers that can be applied for accurately assessing an individual\'s risk for cancer. In this article, we try to find the ideal epigenetic genes involved in colorectal cancer (CRC) based on a CRC database and our CRC cohort. The top 20 genes with an extremely high frequency of hypermethylation in CRC were identified in the latest database. Remarkably, 3 HOXA genes were included in this list and ranked at the top. The percentage of methylation in the HOXA5, HOXA2, and HOXA6 genes in CRC were up to 67.62, 58.36, and 31.32%, respectively, and ranked first in CRC among all human tumor tissues. Paired colorectal tumor samples and adjacent non-tumor colorectal tissue samples and four CRC cell lines were selected for MethylTarget™ assays. The results demonstrated that CRC tissues and cells had a stronger methylation status around the 3 HOXA gene promoter regions compared with adjacent non-tumor colonic tissue samples. The Receiver operator characteristic curve (ROC) curves for HOXA genes show excellent diagnostic ability in distinguishing tissue from healthy individuals and CRC patients, especially for Stage I patients (AUC = 0.9979 in HOXA2, 0.9309 in HOXA5, and 0.8025 in HOXA6). An association analysis between the methylation pattern of HOXA genes and clinical indicators was performed and found that HOXA2 methylation was significantly associated with age, N, stage, M, lymphovascular invasion, perineural invasion, lymph node number. HOXA5 methylation was associated with age, T, M, stage, and tumor status, and HOXA6 methylation was associated with age and KRAS mutation. Notably, we found that the highest methylation of HOXA5 and HOXA2 occurs in the early stages of colorectal cancer tissues such as stage I, N0, MO, and non-invasive tissues. The methylation levels declined as tumors progressed. However, methylation level at any stage of the tumor was still significantly higher than in normal tissues (p < 0.0001). The mRNA of the 3 HOXA genes was downregulated in early tumor stages due to hypermethylation of CpG islands adjacent to the promoters of the genes. In addition, hypermethylation of HOXA5 and HOXA6 mainly occurred in patients < 60 years old and with MSI-L, MSS, CIMP.L and non-CIMP tumors. Together, this suggests that epigenetic silencing of 3 adjacent HOXA genes may be an important event in the progression of colorectal cancer.

Genome-wide association studies (GWAS) have identified rs11672691 at 19q13 associated with aggressive prostate cancer (PCa). Here, we independently confirmed the finding in a cohort of 2,738 PCa patients and discovered the biological mechanism underlying this association. We found an association of the aggressive PCa-associated allele G of rs11672691 with elevated transcript levels of two biologically plausible candidate genes, PCAT19 and CEACAM21, implicated in PCa cell growth and tumor progression. Mechanistically, rs11672691 resides in an enhancer element and alters the binding site of HOXA2, a novel oncogenic transcription factor with prognostic potential in PCa. Remarkably, CRISPR/Cas9-mediated single-nucleotide editing showed the direct effect of rs11672691 on PCAT19 and CEACAM21 expression and PCa cellular aggressive phenotype. Clinical data demonstrated synergistic effects of rs11672691 genotype and PCAT19/CEACAM21 gene expression on PCa prognosis. These results provide a plausible mechanism for rs11672691 associated with aggressive PCa and thus lay the ground work for translating this finding to the clinic.

Cleft palate is a common congenital abnormality that results from defective secondary palate (SP) formation. The Sine oculis-related homeobox 2 (Six2) gene has been linked to abnormalities of craniofacial and kidney development. Our current study examined, for the first time, the specific role of Six2 in embryonic mouse SP development. Six2 mRNA and protein expression were identified in the palatal shelves from embryonic days (E)12.5 to E15.5, with peak levels during early stages of palatal shelf outgrowth. Immunohistochemical staining (IHC) showed that Six2 protein is abundant throughout the mesenchyme in the oral half of each palatal shelf, whereas there is a pronounced decline in Six2 expression by mesenchyme cells in the nasal half of the palatal shelf by stages E14.5-15.5. An opposite pattern was observed in the surface epithelium of the palatal shelf. Six2 expression was prominent at all stages in the epithelial cell layer located on the nasal side of each palatal shelf but absent from the epithelium located on the oral side of the palatal shelf. Six2 is a putative downstream target of transcription factor Hoxa2 and we previously demonstrated that Hoxa2 plays an intrinsic role in embryonic palate formation. We therefore investigated whether Six2 expression was altered in the developing SP of Hoxa2 null mice. Reverse transcriptase PCR and Western blot analyses revealed that Six2 mRNA and protein levels were upregulated in Hoxa2-/- palatal shelves at stages E12.5-14.5. Moreover, the domain of Six2 protein expression in the palatal mesenchyme of Hoxa2-/- embryos was expanded to include the entire nasal half of the palatal shelf in addition to the oral half. The palatal shelves of Hoxa2-/- embryos displayed a higher density of proliferating, Ki-67 positive palatal mesenchyme cells, as well as a higher density of Six2/Ki-67 double-positive cells. Furthermore, Hoxa2-/- palatal mesenchyme cells in culture displayed both increased proliferation and elevated Cyclin D1 expression relative to wild-type cultures. Conversely, siRNA-mediated Six2 knockdown restored proliferation and Cyclin D1 expression in Hoxa2-/- palatal mesenchyme cultures to near wild-type levels. Our findings demonstrate that Six2 functions downstream of Hoxa2 as a positive regulator of mesenchymal cell proliferation during SP development.