Expression profiles of 39 HOX genes in normal human adult organs and anaplastic thyroid cancer cell lines by quantitative real-time RT-PCR system

Role of HOX genes in cancer progression and their therapeutical aspects

HOX genes constitute a family of evolutionarily conserved transcription factors that play pivotal roles in embryonic development, tissue patterning, and cell differentiation. These genes are essential for the precise spatial and temporal control of body axis formation in vertebrates. In addition to their developmental functions, HOX genes have garnered significant attention for their involvement in various diseases, including cancer. Deregulation of HOX gene expression has been observed in numerous malignancies, where they can influence tumorigenesis, progression, and therapeutic responses. This review provides an overview of the diverse roles of HOX genes in development, disease, and potential therapeutic targets, highlighting their significance in understanding biological processes and their potential clinical implications.

A molecular atlas of adult C. elegans motor neurons reveals ancient diversity delineated by conserved transcription factor codes

Motor neurons (MNs) constitute an ancient cell type targeted by multiple adult-onset diseases. It is therefore important to define the molecular makeup of adult MNs in animal models and extract organizing principles. Here, we generate a comprehensive molecular atlas of adult Caenorhabditis elegans MNs and a searchable database. Single-cell RNA sequencing of 13,200 cells reveals that ventral nerve cord MNs cluster into 29 molecularly distinct subclasses. Extending C. elegans Neuronal Gene Expression Map and Network (CeNGEN) findings, all MN subclasses are delineated by distinct expression codes of either neuropeptide or transcription factor gene families. Strikingly, combinatorial codes of homeodomain transcription factor genes succinctly delineate adult MN diversity in both C. elegans and mice. Further, molecularly defined MN subclasses in C. elegans display distinct patterns of connectivity. Hence, our study couples the connectivity map of the C. elegans motor circuit with a molecular atlas of its constituent MNs and uncovers organizing principles and conserved molecular codes of adult MN diversity.

A molecular atlas of adult C. elegans motor neurons reveals ancient diversity delineated by conserved transcription factor codes

Motor neurons (MNs) constitute an ancient cell type targeted by multiple adult-onset diseases. It is therefore important to define the molecular makeup of adult MNs in animal models and extract organizing principles. Here, we generated a comprehensive molecular atlas of adult Caenorhabditis elegans MNs and a searchable database (http://celegans.spinalcordatlas.org). Single-cell RNA-sequencing of 13,200 cells revealed that ventral nerve cord MNs cluster into 29 molecularly distinct subclasses. All subclasses are delineated by unique expression codes of either neuropeptide or transcription factor gene families. Strikingly, we found that combinatorial codes of homeodomain transcription factor genes define adult MN diversity both in C. elegans and mice. Further, molecularly defined MN subclasses in C. elegans display distinct patterns of connectivity. Hence, our study couples the connectivity map of the C. elegans motor circuit with a molecular atlas of its constituent MNs, and uncovers organizing principles and conserved molecular codes of adult MN diversity.

Transcription networks rewire gene repertoire to coordinate cellular reprograming in prostate cancer

Transcription factors (TFs) represent the most commonly deregulated DNA-binding class of proteins associated with multiple human cancers. They can act as transcriptional activators or repressors that rewire the cistrome, resulting in cellular reprogramming during cancer progression. Deregulation of TFs is associated with the onset and maintenance of various cancer types including prostate cancer. An emerging subset of TFs has been implicated in the regulation of multiple cancer hallmarks during tumorigenesis. Here, we discuss the role of key TFs which modulate transcriptional cicuitries involved in the development and progression of prostate cancer. We further highlight the role of TFs associated with key cancer hallmarks, including, chromatin remodeling, genome instability, DNA repair, invasion, and metastasis. We also discuss the pluripotent function of TFs in conferring lineage plasticity, that aids in disease progression to neuroendocrine prostate cancer. At the end, we summarize the current understanding and approaches employed for the therapeutic targeting of TFs and their cofactors in the clinical setups to prevent disease progression.

Three-dimensional genome landscape comprehensively reveals patterns of spatial gene regulation in papillary and anaplastic thyroid cancers: a study using representative cell lines for each cancer type

BACKGROUND

Spatial chromatin structure is intricately linked with somatic aberrations, and somatic mutations of various cancer-related genes, termed co-mutations (CoMuts), occur in certain patterns during cancer initiation and progression. The functional mechanisms underlying these genetic events remain largely unclear in thyroid cancer (TC). With discrepant differentiation, papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC) differ greatly in characteristics and prognosis. We aimed to reveal the spatial gene alterations and regulations between the two TC subtypes.

METHODS

We systematically investigated and compared the spatial co-mutations between ATC (8305C), PTC (BCPAP and TPC-1), and normal thyroid cells (Nthy-ori-3-1). We constructed a framework integrating whole-genome sequencing (WGS), high-throughput chromosome conformation capture (Hi-C), and transcriptome sequencing, to systematically detect the associations between the somatic co-mutations of cancer-related genes, structural variations (SVs), copy number variations (CNVs), and high-order chromatin conformation.

RESULTS

Spatial co-mutation hotspots were enriched around topologically associating domains (TADs) in TC. A common set of 227 boundaries were identified in both ATC and PTC, with significant overlaps between them. The spatial proximities of the co-mutated gene pairs in the two TC types were significantly greater than in the gene-level and overall backgrounds, and ATC cells had higher TAD contact frequency with CoMuts > 10 compared with PTC cells. Compared with normal thyroid cells, in ATC the number of the created novel three-dimensional chromatin structural domains increased by 10%, and the number of shifted TADs decreased by 7%. We found five TAD blocks with CoMut genes/events specific to ATC with certain mutations in genes including MAST-NSUN4, AM129B/TRUB2, COL5A1/PPP1R26, PPP1R26/GPSM1/CCDC183, and PRAC2/DLX4. For the majority of ATC and PTC cells, the HOXA10 and HIF2α signals close to the transcription start sites of CoMut genes within TADs were significantly stronger than those at the background. CNV breakpoints significantly overlapped with TAD boundaries in both TC subtypes. ATCs had more CNV losses overlapping with TAD boundaries, and noncoding SVs involved in intrachromosomal SVs, amplified inversions, and tandem duplication differed between ATC and PTC. TADs with short range were more abundant in ATC than PTC. More switches of A/B compartment types existed in ATC cells compared with PTC. Gene expression was significantly synchronized, and orchestrated by complex epigenetics and regulatory elements.

CONCLUSION

Chromatin interactions and gene alterations and regulations are largely heterogeneous in TC. CNVs and complex SVs may function in the TC genome by interplaying with TADs, and are largely different between ATC and PTC. Complexity of TC genomes, which are highly organized by 3D genome-wide interactions mediating mutational and structural variations and gene activation, may have been largely underappreciated. Our comprehensive analysis may provide key evidence and targets for more customized diagnosis and treatment of TC.

Maintenance of neurotransmitter identity by Hox proteins through a homeostatic mechanism

Hox transcription factors play fundamental roles during early patterning, but they are also expressed continuously, from embryonic stages through adulthood, in the nervous system. However, the functional significance of their sustained expression remains unclear. In C. elegans motor neurons (MNs), we find that LIN-39 (Scr/Dfd/Hox4-5) is continuously required during post-embryonic life to maintain neurotransmitter identity, a core element of neuronal function. LIN-39 acts directly to co-regulate genes that define cholinergic identity (e.g., unc-17/VAChT, cho-1/ChT). We further show that LIN-39, MAB-5 (Antp/Hox6-8) and the transcription factor UNC-3 (Collier/Ebf) operate in a positive feedforward loop to ensure continuous and robust expression of cholinergic identity genes. Finally, we identify a two-component design principle for homeostatic control of Hox gene expression in adult MNs: Hox transcriptional autoregulation is counterbalanced by negative UNC-3 feedback. These findings uncover a noncanonical role for Hox proteins during post-embryonic life, critically broadening their functional repertoire from early patterning to the control of neurotransmitter identity.

Control of spinal motor neuron terminal differentiation through sustained Hoxc8 gene activity

Spinal motor neurons (MNs) constitute cellular substrates for several movement disorders. Although their early development has received much attention, how spinal MNs become and remain terminally differentiated is poorly understood. Here, we determined the transcriptome of mouse MNs located at the brachial domain of the spinal cord at embryonic and postnatal stages. We identified novel transcription factors (TFs) and terminal differentiation genes (e.g. ion channels, neurotransmitter receptors, adhesion molecules) with continuous expression in MNs. Interestingly, genes encoding homeodomain TFs (e.g. HOX, LIM), previously implicated in early MN development, continue to be expressed postnatally, suggesting later functions. To test this idea, we inactivated Hoxc8 at successive stages of mouse MN development and observed motor deficits. Our in vivo findings suggest that Hoxc8 is not only required to establish, but also maintain expression of several MN terminal differentiation markers. Data from in vitro generated MNs indicate Hoxc8 acts directly and is sufficient to induce expression of terminal differentiation genes. Our findings dovetail recent observations in Caenorhabditis elegans MNs, pointing toward an evolutionarily conserved role for Hox in neuronal terminal differentiation.

Emerging Roles for Hox Proteins in the Last Steps of Neuronal Development in Worms, Flies, and Mice

A remarkable diversity of cell types characterizes every animal nervous system. Previous studies provided important insights into how neurons commit to a particular fate, migrate to the right place and form precise axodendritic patterns. However, the mechanisms controlling later steps of neuronal development remain poorly understood. Hox proteins represent a conserved family of homeodomain transcription factors with well-established roles in anterior-posterior (A-P) patterning and the early steps of nervous system development, including progenitor cell specification, neuronal migration, cell survival, axon guidance and dendrite morphogenesis. This review highlights recent studies in Caenorhabditis elegans, Drosophila melanogaster and mice that suggest new roles for Hox proteins in processes occurring during later steps of neuronal development, such as synapse formation and acquisition of neuronal terminal identity features (e.g., expression of ion channels, neurotransmitter receptors, and neuropeptides). Moreover, we focus on exciting findings suggesting Hox proteins are required to maintain synaptic structures and neuronal terminal identity during post-embryonic life. Altogether, these studies, in three model systems, support the hypothesis that certain Hox proteins are continuously required, from early development throughout post-embryonic life, to build and maintain a functional nervous system, significantly expanding their functional repertoire beyond the control of early A-P patterning.

Digital biomarker 2D:4D as a predictor of cancer: A systematic review

BACKGROUND

The digital ratio between the second and fourth digits of the hands, known as 2D:4D, is sexually dimorphic. It has been suggested that a low 2D:4D indicates high exposure to prenatal testosterone and low estrogen exposure while a high 2D:4D indicates the inverse. The 2D:4D may be predictive of cancer susceptibility, and this may be particularly true in cancers that show differences between sexes in their occurrence.

AIM

To conduct a systematic review of published epidemiological literature examining the association between 2D:4D and cancer.

METHOD

This review was carried out according to criteria recommended for the systematic review of Statement PRISMA. We enrolled 25 papers involving eleven cancer topographies with 4,569 cases and 19,416 controls from Europe, America, Asia and Australia.

RESULTS

We noticed variations and discrepancies in the results of the association between 2D:4D and cancer among the studies, either in those that had evaluated the same or different types of cancer, or in the same or distinct lateralities. However, a high 2D:4D was considered a likely predictor of cancer risk in 11 of 25 studies, a low 2D:4D was suggested as a predictor of risk in eight papers, and five of the twenty-five studies did not demonstrate any association.

CONCLUSIONS

Although this biomarker has the advantage of being easy to measure, it is noted that its relationship with sex hormone levels at specific stages of life has not yet been well quantified, and it has still been questioned. Hence, it is suggested that those findings from studies involving 2D:4D as a proxy for foetal hormone exposure should be interpreted with caution, as well as those studies which claim its association with cancer. Thus, this review shows the need for a greater number of epidemiological studies using more homogeneous methodology and techniques to better investigate the strength of the findings.

Molecular Classification and Therapeutic Targets in Ependymoma

Ependymoma is a biologically diverse tumor wherein molecular classification has superseded traditional histological grading based on its superior ability to characterize behavior, prognosis, and possible targeted therapies. The current, updated molecular classification of ependymoma consists of ten distinct subgroups spread evenly among the spinal, infratentorial, and supratentorial compartments, each with its own distinct clinical and molecular characteristics. In this review, the history, histopathology, standard of care, prognosis, oncogenic drivers, and hypothesized molecular targets for all subgroups of ependymoma are explored. This review emphasizes that despite the varied behavior of the ependymoma subgroups, it remains clear that research must be performed to further elucidate molecular targets for these tumors. Although not all ependymoma subgroups are oncologically aggressive, development of targeted therapies is essential, particularly for cases where surgical resection is not an option without causing significant morbidity. The development of molecular therapies must rely on building upon our current understanding of ependymoma oncogenesis, as well as cultivating transfer of knowledge based on malignancies with similar genomic alterations.

Expression of the HOXA gene family and its relationship to prognosis and immune infiltrates in cervical cancer

Background

The homeobox A cluster (HOXA) gene family is participated in multiple biological functions in human cancers. To date, little is known about the expression profile and clinical significance of HOXA genes in cervical cancer.

Methods

We downloaded RNASeq data of cervical cancer from The Cancer Genome Atlas (TCGA) database. The difference in HOXA family expression was analyzed using independent samples t test. Cox proportional hazard regression analysis was used to assess the effect of HOXA family expression on survival, and a nomogram predicting survival was generated. We assessed the infiltration difference in immune cells and expression difference of immunity biomarkers between two groups with different expression level of HOXA genes through Immune Cell Abundance Identifier (ImmuCellAI) and independent samples t test, respectively.

Results

Our results showed that the HOXA1 gene was upregulated, while the HOXA10 and HOXA11 were downregulated in cervical cancer. Downregulation of HOXA1 was related to a poor outcome for cervical cancer patient. We also identified a significantly increased abundance of T helper 2 cells (Th2) and higher expression of PD‐L1 in cervical cancer patients with lower expression of HOXA10 and HOXA11. The gene set enrichment analysis (GSEA) results indicated that HOXA1 and HOXA11 were involved in immune responses pathways and participated in the activation of a variety of classic signaling pathways related to the progression of human cancer.

Conclusion

This study comprehensively analyzed different HOXA genes applying public database to determine their expression patterns, potential diagnostic, prognostic, and treatment values in cervical cancer.

Homeobox-A13 acts as a functional prognostic and diagnostic biomarker via regulating P53 and Wnt signaling pathways in lung cancer

BACKGROUND

The prognosis of lung cancer patients is poor without useful prognostic and diagnostic biomarker. To search for novel prognostic and diagnostic markers, we previously found homeobox-A13 (HOXA13) as a promising candidate in lung cancer.

OBJECTIVE

To determine the precisely clinical feature, prognostic and diagnostic value, possible role and mechanism of HOXA13.

METHODS

Gene-expression was explored by real-time quantitative-PCR, western-blot and tissue-microarray. The associations were analyzed by Chi-square test, Kaplan-Meier and Cox-regression. The roles and mechanisms were evaluated by MTS, EdU, transwell, xenograft tumor and luciferase-reporter assays.

RESULTS

HOXA13 expression is increased in tumors, and correlated with age of patients. HOXA13 expression is associated with unfavorable overall survival and relapse-free survival of patients in four cohorts. Interestingly, HOXA13 has different prognostic significance in adenocarcinoma (ADC) and squamous-cell carcinoma (SCC), and is a sex- and smoke-related prognostic factor only in ADC. Importantly, HOXA13 can serve as a diagnostic biomarker for lung cancer, especially for SCC. HOXA13 can promote cancer-cell proliferation, migration and invasion in vitro, and facilitate tumorigenicity and tumor metastasis in vivo. HOXA13 acts the oncogenic roles on tumor growth and metastasis by regulating P53 and Wnt/β-catenin signaling activities in lung cancer.

CONCLUSIONS

HOXA13 is a new prognostic and diagnostic biomarker associated with P53 and Wnt/β-catenin signaling pathways.

HomeoboxC6 affects the apoptosis of human vascular endothelial cells and is involved in atherosclerosis

Apoptosis of vascular endothelial cells (VECs) is highly important in the occurrence and development of atherosclerosis (AS). HomeboxC6 (HOXC6) is expressed in higher levels in multiple malignant tissues, and it influences the malignant biological behavior of the cancer cells. However, the effects of HOXC6 on AS and the apoptosis of VECs have not been fully elucidated. In this study, we demonstrated that HOXC6 expression was increased in aortic wall of AS rats and peripheral blood monocytes of patients with coronary heart disease. Furthermore, it was uncovered that BAX expression was upregulated, while BCL-2 expression was downregulated in the aortic wall of AS rats. The apoptosis of human VECs (HVECs) cultured normally or treated with oxidized low-density lipoprotein in vitro was decreased after transfection with HOXC6-siRNA. Moreover, the results of Western blot analysis unveiled that the expressions of proapoptotic proteins, such as BAX, caspase-3, cleaved-caspase-3, and caspase-9 were reduced, while the expression of antiapoptotic protein, BCL-2, was elevated. Meanwhile, mRNA and protein expressions of phospholipase C beta (PLCβ) were decreased, the phosphorylation levels of protein kinase C zeta (PKCζ) and nuclear transcription factor-κB-p65 (NF-κBp65) and the membrane translocation of PKCζ were reduced as well. Besides, the expression of interleukin-18 (IL-18) protein was downregulated. However, after overexpression of HOXC6, the opposite trends of the abovementioned indices were observed. Furthermore, the inhibition of apoptosis induced by HOXC6-siRNA was reversed by lysophosphatidylcholine, an activator of PKCζ. Taken together, our results indicated that HOXC6 can promote the apoptosis of HVECs and may be involved in the occurrence and development of AS, which may be partially associated with the activation of PLCβ/PKCζ/NF-κBp65/IL-18 signaling pathway.

Induction of HOX Genes by Hepatitis C Virus Infection via Impairment of Histone H2A Monoubiquitination

Hepatitis C virus (HCV) infection causes liver pathologies, including hepatocellular carcinoma (HCC). Homeobox (HOX) gene products regulate embryonic development and are associated with tumorigenesis, although the regulation of HOX genes by HCV infection has not been clarified in detail. We examined the effect of HCV infection on HOX gene expression. In this study, HCV infection induced more than half of the HOX genes and reduced the level of histone H2A monoubiquitination on lysine 119 (K119) (H2Aub), which represses HOX gene promoter activity. HCV infection also promoted proteasome-dependent degradation of RNF2, which is an E3 ligase mediating H2A monoubiquitination as a component of polycomb repressive complex 1. Since full-genomic replicon cells but not subgenomic replicon cells exhibited reduced RNF2 and H2Aub levels and induction of HOX genes, we focused on the core protein. Expression of the core protein reduced the amounts of RNF2 and H2Aub and induced HOX genes. Treatment with LY-411575, which can reduce HCV core protein expression via signal peptide peptidase (SPP) inhibition without affecting other viral proteins, dose-dependently restored the amounts of RNF2 and H2Aub in HCV-infected cells and impaired the induction of HOX genes and production of viral particles but not viral replication. The chromatin immunoprecipitation assay results also indicated infection- and proteasome-dependent reductions in H2Aub located in HOX gene promoters. These results suggest that HCV infection or core protein induces HOX genes by impairing histone H2A monoubiquitination via a reduction in the RNF2 level.IMPORTANCE Recently sustained virologic response can be achieved by direct-acting antiviral (DAA) therapy in most hepatitis C patients. Unfortunately, DAA therapy does not completely eliminate a risk of hepatocellular carcinoma (HCC). Several epigenetic factors, including histone modifications, are well known to contribute to hepatitis C virus (HCV)-associated HCC. However, the regulation of histone modifications by HCV infection has not been clarified in detail. In this study, our data suggest that HCV infection or HCV core protein expression impairs monoubiquitination of histone H2A K119 in the homeobox (HOX) gene promoter via destabilization of RNF2 and then induces HOX genes. Several lines of evidence suggest that the expression of several HOX genes is dysregulated in certain types of tumors. These findings reveal a novel mechanism of HCV-related histone modification and may provide information about new targets for diagnosis and prevention of HCC occurrence.

Oncogenic and tumor suppressor function of MEIS and associated factors

MEIS proteins are historically associated with tumorigenesis, metastasis, and invasion in cancer. MEIS and associated PBX-HOX proteins may act as tumor suppressors or oncogenes in different cellular settings. Their expressions tend to be misregulated in various cancers. Bioinformatic analyses have suggested their upregulation in leukemia/lymphoma, thymoma, pancreas, glioma, and glioblastoma, and downregulation in cervical, uterine, rectum, and colon cancers. However, every cancer type includes, at least, a subtype with high MEIS expression. In addition, studies have highlighted that MEIS proteins and associated factors may function as diagnostic or therapeutic biomarkers for various diseases. Herein, MEIS proteins and associated factors in tumorigenesis are discussed with recent discoveries in addition to how they could be modulated by noncoding RNAs or newly developed small-molecule MEIS inhibitors.

HOXA5 Expression Is Elevated in Breast Cancer and Is Transcriptionally Regulated by Estradiol

HOXA5 is a homeobox-containing gene associated with the development of the lung, gastrointestinal tract, and vertebrae. Here, we investigate potential roles and the gene regulatory mechanism in HOXA5 in breast cancer cells. Our studies demonstrate that HOXA5 expression is elevated in breast cancer tissues and in estrogen receptor (ER)-positive breast cancer cells. HOXA5 expression is critical for breast cancer cell viability. Biochemical studies show that estradiol (E2) regulates HOXA5 gene expression in cultured breast cancer cells in vitro. HOXA5 expression is also upregulated in vivo in the mammary tissues of ovariectomized female rats. E2-induced HOXA5 expression is coordinated by ERs. Knockdown of either ERα or ERβ downregulated E2-induced HOXA5 expression. Additionally, ER co-regulators, including CBP/p300 (histone acetylases) and MLL-histone methylases (MLL2, MLL3), histone acetylation-, and H3K4 trimethylation levels are enriched at the HOXA5 promoter in present E2. In summary, our studies demonstrate that HOXA5 is overexpressed in breast cancer and is transcriptionally regulated via estradiol in breast cancer cells.

HOX gene cluster (de)regulation in brain: from neurodevelopment to malignant glial tumours

HOX genes encode a family of evolutionarily conserved homeodomain transcription factors that are crucial both during development and adult life. In humans, 39 HOX genes are arranged in four clusters (HOXA, B, C, and D) in chromosomes 7, 17, 12, and 2, respectively. During embryonic development, particular epigenetic states accompany their expression along the anterior-posterior body axis. This tightly regulated temporal-spatial expression pattern reflects their relative chromosomal localization, and is critical for normal embryonic brain development when HOX genes are mainly expressed in the hindbrain and mostly absent in the forebrain region. Epigenetic marks, mostly polycomb-associated, are dynamically regulated at HOX loci and regulatory regions to ensure the finely tuned HOX activation and repression, highlighting a crucial epigenetic plasticity necessary for homeostatic development. HOX genes are essentially absent in healthy adult brain, whereas they are detected in malignant brain tumours, namely gliomas, where HOX genes display critical roles by regulating several hallmarks of cancer. Here, we review the major mechanisms involved in HOX genes (de)regulation in the brain, from embryonic to adult stages, in physiological and oncologic conditions. We focus particularly on the emerging causes of HOX gene deregulation in glioma, as well as on their functional and clinical implications.

Establishment and maintenance of motor neuron identity via temporal modularity in terminal selector function

Terminal selectors are transcription factors (TFs) that establish during development and maintain throughout life post-mitotic neuronal identity. We previously showed that UNC-3/Ebf, the terminal selector of C. elegans cholinergic motor neurons (MNs), acts indirectly to prevent alternative neuronal identities (Feng et al., 2020). Here, we globally identify the direct targets of UNC-3. Unexpectedly, we find that the suite of UNC-3 targets in MNs is modified across different life stages, revealing ‘temporal modularity’ in terminal selector function. In all larval and adult stages examined, UNC-3 is required for continuous expression of various protein classes (e.g. receptors, transporters) critical for MN function. However, only in late larvae and adults, UNC-3 is required to maintain expression of MN-specific TFs. Minimal disruption of UNC-3’s temporal modularity via genome engineering affects locomotion. Another C. elegans terminal selector (UNC-30/Pitx) also exhibits temporal modularity, supporting the potential generality of this mechanism for the control of neuronal identity.

Contributions of HOX genes to cancer hallmarks: Enrichment pathway analysis and review

Homeobox genes function as master regulatory transcription factors during development, and their expression is often altered in cancer. The HOX gene family was initially studied intensively to understand how the expression of each gene was involved in forming axial patterns and shaping the body plan during embryogenesis. More recent investigations have discovered that HOX genes can also play an important role in cancer. The literature has shown that the expression of HOX genes may be increased or decreased in different tumors and that these alterations may differ depending on the specific HOX gene involved and the type of cancer being investigated. New studies are also emerging, showing the critical role of some members of the HOX gene family in tumor progression and variation in clinical response. However, there has been limited systematic evaluation of the various contributions of each member of the HOX gene family in the pathways that drive the common phenotypic changes (or "hallmarks") and that underlie the transformation of normal cells to cancer cells. In this review, we investigate the context of the engagement of HOX gene targets and their downstream pathways in the acquisition of competence of tumor cells to undergo malignant transformation and tumor progression. We also summarize published findings on the involvement of HOX genes in carcinogenesis and use bioinformatics methods to examine how their downstream targets and pathways are involved in each hallmark of the cancer phenotype.

Quantitative Analysis of Differential Expression of HOX Genes in Multiple Cancers

Transcription factors encoded by Homeobox (HOX) genes play numerous key functions during early embryonic development and differentiation. Multiple reports have shown that mis-regulation of HOX gene expression plays key roles in the development of cancers. Their expression levels in cancers tend to differ based on tissue and tumor type. Here, we performed a comprehensive analysis comparing HOX gene expression in different cancer types, obtained from The Cancer Genome Atlas (TCGA), with matched healthy tissues, obtained from Genotype-Tissue Expression (GTEx). We identified and quantified differential expression patterns that confirmed previously identified expression changes and highlighted new differential expression signatures. We discovered differential expression patterns that are in line with patient survival data. This comprehensive and quantitative analysis provides a global picture of HOX genes' differential expression patterns in different cancer types.

A terminal selector prevents a Hox transcriptional switch to safeguard motor neuron identity throughout life

To become and remain functional, individual neuron types must select during development and maintain throughout life their distinct terminal identity features, such as expression of specific neurotransmitter receptors, ion channels and neuropeptides. Here, we report a molecular mechanism that enables cholinergic motor neurons (MNs) in the C. elegans ventral nerve cord to select and maintain their unique terminal identity. This mechanism relies on the dual function of the conserved terminal selector UNC-3 (Collier/Ebf). UNC-3 synergizes with LIN-39 (Scr/Dfd/Hox4-5) to directly co-activate multiple terminal identity traits specific to cholinergic MNs, but also antagonizes LIN-39’s ability to activate terminal features of alternative neuronal identities. Loss of unc-3 causes a switch in the transcriptional targets of LIN-39, thereby alternative, not cholinergic MN-specific, terminal features become activated and locomotion defects occur. The strategy of a terminal selector preventing a transcriptional switch may constitute a general principle for safeguarding neuronal identity throughout life.

Whole-Genome and Segmental Homozygosity Confirm Errors in Meiosis as Etiology of Struma Ovarii

Strumae ovarii are neoplasms composed of normal-appearing thyroid tissue that occur within the ovary and rarely spread to extraovarian sites. A unique case of struma ovarii with widespread dissemination detected 48 years after removal of a pelvic dermoid provided the opportunity to reexamine the molecular nature of this form of neoplasm. One tumor, from the heart, consisting of benign thyroid tissue was found to have whole-genome homozygosity. Another tumor from the right mandible composed of malignant-appearing thyroid tissue showed whole-genome homozygosity and a deletion of 7p, presumably the second hit that transformed it into a cancerous tumor. Specimens from 2 other cases of extraovarian struma confined to the abdomen and 8 of 9 cases of intraovarian struma showed genome-wide segmental homozygosity. These findings confirm errors in meiosis as the origin of struma ovarii. The histological and molecular findings further demonstrate that even when outside the ovary, strumae ovarii can behave nonaggressively until they receive a second hit, thereafter behaving like cancer.

Use of homeobox gene expression patterns to determine anatomical regions of origin for body surface tissues derived from adult mice

Anatomical regions of the skin have distinct functions and anatomical characteristics, including thicker or thinner epidermis, more or fewer hair follicles, and lighter or darker skin. For a better therapeutic outcome of skin transplantation, site-specific characteristics of grafted tissues need to be taken into account in terms of their functionality and beauty. However, there is no method for evaluating positional information of epidermal cells. Homeobox genes are expressed along the anterior-posterior axis and direct the body plan in the animal development process. Although the expression of several HOX genes is known to be retained as the positional information in adult tissue, their expression patterns in the body surface tissues in adult mammals are still incompletely understood. In this study, we investigated the expression patterns of 40 homeobox genes, including 39 Hox genes and the paired box 6 (Pax6) gene, in body surface tissues of adult mice. On the basis of the results obtained, we proposed, for the first time, a method for determining anatomical regions of origin for body surface tissues derived from adult mice using Hox genes and Pax6. Evaluation of expression levels of at least 7 Hox genes and Pax6 should be sufficient to distinguish 11 anatomical body surface tissues derived from the adult mouse body. The proposed method may be useful not only for determining the origin of surface tissues from specific anatomical regions of the mammalian body but also for predicting positional information of epithelial cells generated from pluripotent stem cells.

Functional analysis of HOXA10 and HOXB4 in human medulloblastoma cell lines

Medulloblastoma (MB) is a malignant childhood brain tumor which at molecular level is classified into at least four major subtypes: WNT, SHH, group C and group D differing in response to treatment. Previous studies have associated changes in expression levels and activation of certain HOX genes with MB development. In the present study, we investigate the role of HOX genes in two attributes acquired by tumor cells: migration and proliferation potential, as well as, in vivo tumorigenic potential. We analyzed UW402, UW473, DAOY and ONS-76 human pediatric MB cell lines and cerebellum primary cultures. Two-color microarray-based gene expression analysis was used to identify differentially expressed HOX genes. Among the various HOX genes significantly overexpressed in DAOY and ONS-76 cell lines compared to UW402 and UW473 cell lines, HOXA10 and HOXB4 were selected for further analysis. The expression levels of these HOX genes were validated by real-time PCR. A mouse model was used to study the effect of the HOXA10 and HOXB4 genes on the in vivo tumorigenic potential and the in vitro proliferative and migration potential of MB cell lines. Our results show that the inhibition of HOXA10 in DAOY cell line led to increased in vitro cell migration while in vitro cell proliferation or in vivo tumorigenic potential were unaffected. We also observed that induced expression of HOXB4 in the UW473 cell line significantly reduced in vitro cell proliferation and migration capability of UW473 cells with no effect on the in vivo tumorigenicity. This suggests that HOXA10 plays a role in migration events and the HOXB4 gene is involved in proliferation and migration processes of medulloblastoma cells, however, it appears that these genes are not essential for the tumorigenic process of these cells.

HOXA13 is associated with unfavorable survival and acts as a novel oncogene in prostate carcinoma

AIM

To investigate the clinical relevance and functional role of HOXA13 in prostate cancer Methods: PCR, western blot and immunohistochemistry were performed to determine the expression. Kaplan-Meier and Cox regression survival analyses investigated the clinical relevance. Cell viability, flow cytometry and transwell assays were used to determine the functional roles.

RESULTS

HOXA13 expression is sharply increased in carcinoma tissues and is significantly associated with poor prognosis of prostate cancer patients. Interestingly, nucleus not cytoplasm HOXA13 expression is associated with unfavorable survival of the patients. Furthermore, nucleus HOXA13 expression represents an unfavorable and independent prognosis factor of histological grade 2 or Gleason grade <8 patients. Functionally, forced expression of HOXA13 obviously promotes tumor cell proliferation, migration and invasion, whereas inhibits tumor cell apoptosis.

CONCLUSION

HOXA13 is an unfavorable prognostic factor and a novel oncogene for prostate cancer.

Prognostic significance of the digit ratio after hormone therapy for prostate cancer: a prospective multicenter study

The digit ratio has been used as a retrospective noninvasive biomarker to investigate the putative effects of prenatal exposure to androgens. In recent years, many scholars have paid attention to the association between 2D:4D (the second and fourth digits) and prostatic cancer. This study explored the prognostic significance of digit ratio in prostate cancer patients. We reviewed the progressive status and survival of 382 prostate cancer patients who had received hormone therapy at our institutions. Survival of clinicopathological variables analyzed as categorical variables were determined by the log-rank test. According to Cox’s proportional hazards analysis, R2D:4D, L2D:4D, PSA at 6 month,bone metastasis were significant independent factors for prostate cancer. The risk of any progression of prostate cancer similarly depressed with increasing 2D:4D, for any progression (R2D:4D HR = 0.71, p = 0.003; L2D:4D HR = 0.67, p = 0.001), for cancer-specific death (R2D:4D HR = 0.67, p = 0.025; L2D:4D HR = 0.74, p = 0.036). Digit ratio may not only have predictive value in risk but also prognosis of prostatic cancer. This finding suggests that low 2D:4D can be used as prognostic factors to identify patients with a poor prognosis. These patients may benefit from more aggressive management.

Homeodomain-containing gene 10 inhibits cell apoptosis and promotes cell invasion and migration in osteosarcoma cell lines

Homeodomain-containing gene 10 (HOXC10) belongs to the homeobox family, which encodes a highly conserved family of transcription factors that plays an important role in morphogenesis in all multicellular organisms. Altered expressions of HOXC10 have been reported in several malignancies. This study was aimed to reveal the expression profile of HOXC10 in osteosarcoma and evaluated whether HOXC10 is a molecular target for cancer therapy. We found that HOXC10 was up-regulated in osteosarcoma tissues compared with bone cyst specimens from The Cancer Genome Atlas database. Osteosarcoma MG63 cells were infected with HOXC10 shRNA expressing vector, and 143B cells were infected with HOXC10 expressing vector. We found that reduced expression of HOXC10 markedly impaired the ability of proliferation, invasion, and migration, and promoted cell apoptosis in vitro and in vivo. Up-regulated expression of HOXC10 promoted the proliferation, invasion, and migration, and inhibited apoptosis of 143B cells. Additionally, HOXC10 regulated apoptosis and migration via modulating expression of Bax/Bcl-2, caspase-3, MMP-2/MMP-9, and E-cadherin in both MG63 and 143B cells and in vivo. These results indicated that HOXC10 might be a diagnostic marker for osteosarcoma and could be a potential molecular target for the therapy of osteosarcoma.

HOXB13 mutations and binding partners in prostate development and cancer: Function, clinical significance, and future directions

The recent and exciting discovery of germline HOXB13 mutations in familial prostate cancer has brought HOX signaling to the forefront of prostate cancer research. An enhanced understanding of HOX signaling, and the co-factors regulating HOX protein specificity and transcriptional regulation, has the high potential to elucidate novel approaches to prevent, diagnose, stage, and treat prostate cancer. Toward our understanding of HOX biology in prostate development and prostate cancer, basic research in developmental model systems as well as other tumor sites provides a mechanistic framework to inform future studies in prostate biology. Here we describe our current understanding of HOX signaling in genitourinary development and cancer, current clinical data of HOXB13 mutations in multiple cancers including prostate cancer, and the role of HOX protein co-factors in development and cancer. These data highlight numerous gaps in our understanding of HOX function in the prostate, and present numerous potentially impactful mechanistic and clinical opportunities for future investigation.

Hox genes in the adult skeleton: Novel functions beyond embryonic development

Hox genes encode evolutionarily conserved transcription factors that control skeletal patterning in the developing embryo. They are expressed in regionally restricted domains and function to regulate the morphology of specific vertebral and long bone elements. Recent work has provided evidence that Hox genes continue to be regionally expressed in adult tissues. Fibroblasts cultured from adult tissues show broadly maintained Hox gene expression patterns. In the adult skeleton, Hox genes are expressed in progenitor-enriched populations of mesenchymal stem/stromal cells (MSCs), and genetic loss-of-function analyses have provided evidence that Hox genes function during the fracture healing process. This review will highlight our current understanding of Hox expression in the adult animal and its function in skeletal regeneration. Developmental Dynamics 246:310-317, 2017. © 2016 Wiley Periodicals, Inc.

Diversity of human and mouse homeobox gene expression in development and adult tissues

Background

Homeobox genes encode a diverse set of transcription factors implicated in a vast range of biological processes including, but not limited to, embryonic cell fate specification and patterning. Although numerous studies report expression of particular sets of homeobox genes, a systematic analysis of the tissue specificity of homeobox genes is lacking.

Results

Here we analyse publicly-available transcriptome data from human and mouse developmental stages, and adult human tissues, to identify groups of homeobox genes with similar expression patterns. We calculate expression profiles for 242 human and 278 mouse homeobox loci across a combination of 59 human and 12 mouse adult tissues, early and late developmental stages. This revealed 20 human homeobox genes with widespread expression, primarily from the TALE, CERS and ZF classes. Most homeobox genes, however, have greater tissue-specificity, allowing us to compile homeobox gene expression lists for neural tissues, immune tissues, reproductive and developmental samples, and for numerous organ systems. In mouse development, we propose four distinct phases of homeobox gene expression: oocyte to zygote; 2-cell; 4-cell to blastocyst; early to mid post-implantation. The final phase change is marked by expression of ANTP class genes. We also use these data to compare expression specificity between evolutionarily-based gene classes, revealing that ANTP, PRD, LIM and POU homeobox gene classes have highest tissue specificity while HNF, TALE, CUT and CERS are most widely expressed.

Conclusions

The homeobox genes comprise a large superclass and their expression patterns are correspondingly diverse, although in a broad sense related to an evolutionarily-based classification. The ubiquitous expression of some genes suggests roles in general cellular processes; in contrast, most human homeobox genes have greater tissue specificity and we compile useful homeobox datasets for particular tissues, organs and developmental stages. The identification of a set of eutherian-specific homeobox genes peaking from human 8-cell to morula stages suggests co-option of new genes to new developmental roles in evolution.

Electronic supplementary material

The online version of this article (doi:10.1186/s12861-016-0140-y) contains supplementary material, which is available to authorized users.

HOXB4 Gene Expression Is Regulated by CDX2 in Intestinal Epithelial Cells

The mammalian Caudal-related homeobox transcription factor 2 (CDX2) plays a key role in the homeobox regulatory network and is essential in regulating the expression of several homeobox (HOX) genes during embryonic development, particularly in the gut. Genome-wide CDX2 chromatin immunoprecipitation analysis and expression data from Caco2 cells also suggests a role for CDX2 in the regulation of HOXB4 gene expression in the intestinal epithelium. Thus, the aim of this study was to investigate whether HOXB4 gene expression is regulated by CDX2 in the intestinal epithelium. We demonstrated binding of CDX2 to four different CDX2 binding sites in an enhancer region located upstream of the HOXB4 transcription start site. Mutations in the CDX2 binding sites reduced HOXB4 gene activity, and knock down of endogenous CDX2 expression by shRNA reduced HOXB4 gene expression. This is the first report demonstrating the CDX2 regulation of HOXB4 gene expression in the developed intestinal epithelium, indicating a possible role for HOXB4 in intestinal homeostasis.

On Expression Patterns and Developmental Origin of Human Brain Regions

Anatomical substructures of the human brain have characteristic cell-types, connectivity and local circuitry, which are reflected in area-specific transcriptome signatures, but the principles governing area-specific transcription and their relation to brain development are still being studied. In adult rodents, areal transcriptome patterns agree with the embryonic origin of brain regions, but the processes and genes that preserve an embryonic signature in regional expression profiles were not quantified. Furthermore, it is not clear how embryonic-origin signatures of adult-brain expression interplay with changes in expression patterns during development. Here we first quantify which genes have regional expression-patterns related to the developmental origin of brain regions, using genome-wide mRNA expression from post-mortem adult human brains. We find that almost all human genes (92%) exhibit an expression pattern that agrees with developmental brain-region ontology, but that this agreement changes at multiple phases during development. Agreement is particularly strong in neuron-specific genes, but also in genes that are not spatially correlated with neuron-specific or glia-specific markers. Surprisingly, agreement is also stronger in early-evolved genes. We further find that pairs of similar genes having high agreement to developmental region ontology tend to be more strongly correlated or anti-correlated, and that the strength of spatial correlation changes more strongly in gene pairs with stronger embryonic signatures. These results suggest that transcription regulation of most genes in the adult human brain is spatially tuned in a way that changes through life, but in agreement with development-determined brain regions.

Underexpression of HOXA11 Is Associated with Treatment Resistance and Poor Prognosis in Glioblastoma

Purpose

Homeobox (HOX) genes are essential developmental regulators that should normally be in the silenced state in an adult brain. The aberrant expression of HOX genes has been associated with the prognosis of many cancer types, including glioblastoma (GBM). This study examined the identity and role of HOX genes affecting GBM prognosis and treatment resistance.

Materials and Methods

The full series of HOX genes of five pairs of initial and recurrent human GBM samples were screened by microarray analysis to determine the most plausible candidate responsible for GBM prognosis. Another 20 newly diagnosed GBM samples were used for prognostic validation. In vitro experiments were performed to confirm the role of HOX in treatment resistance. Mediators involved in HOX gene regulation were searched using differentially expressed gene analysis, gene set enrichment tests, and network analysis.

Results

The underexpression of HOXA11 was identified as a consistent signature for a poor prognosis among the HOX genes. The overall survival of the GBM patients indicated a significantly favorable prognosis in patients with high HOXA11 expression (31±15.3 months) compared to the prognoses in thosewith low HOXA11 expression (18±7.3 months, p=0.03). When HOXA11 was suppressed in the GBM cell lines, the anticancer effect of radiotherapy and/or temozolomide declined. In addition, five candidate mediators (TGFBR2, CRIM1, TXNIP, DPYSL2, and CRMP1) that may confer an oncologic effect after HOXA11 suppression were identified.

Conclusion

The treatment resistance induced by the underexpression of HOXA11 can contribute to a poor prognosis in GBM. Further investigation will be needed to confirm the value of HOXA11 as a potential target for overcoming the treatment resistance by developing chemo- or radiosensitizers.

Endocrine disrupting chemical, bisphenol-A, induces breast cancer associated gene HOXB9 expression in vitro and in vivo

HOXB9 is a homeobox-containing gene that plays a key role in mammary gland development and is associated with breast and other types of cancer. Here, we demonstrate that HOXB9 expression is transcriptionally regulated by estradiol (E2), in vitro and in vivo. We also demonstrate that the endocrine disrupting chemical bisphenol-A (BPA) induces HOXB9 expression in cultured human breast cancer cells (MCF7) as well as in vivo in the mammary glands of ovariectomized (OVX) rats. Luciferase assay showed that estrogen-response-elements (EREs) in the HOXB9 promoter are required for BPA-induced expression. Estrogen-receptors (ERs) and ER-co-regulators such as MLL-histone methylase (MLL3), histone acetylases, CBP/P300, bind to the HOXB9 promoter EREs in the presence of BPA, modify chromatin (histone methylation and acetylation) and lead to gene activation. In summary, our results demonstrate that BPA exposure, like estradiol, increases HOXB9 expression in breast cells both in vitro and in vivo through a mechanism that involves increased recruitment of transcription and chromatin modification factors.

Comparison of digit ratio (2D:4D) between Brazilian men with and without prostate cancer

BACKGROUND

Digit ratio (2D:4D) has been suggested as a proxy biomarker for prenatal androgen activity and has been linked to prostate cancer, as the genes that regulate the formation and differentiation of the fingers are also related to the carcinogenesis of prostate cancer. To investigate the possible correlation between right hand, left hand and right hand minus left hand (DR-L) 2D:4D and prostate cancer of Brazilian subjects by comparing 2D:4D ratios of individuals diagnosed with prostate cancer and individuals without the disease. Also, to inquire the relationship between 2D:4D and severity of prostate cancer through Gleason scores.

METHODS

Digital measurements of the lengths of the index and ring fingers of both hands of patients diagnosed with prostate cancer (PCA group, n=100) and healthy control individuals (n=100) were obtained using a digital vernier caliper. Means of the 2D:4D ratios were compared. Data were analyzed by the Student's t-test for unpaired samples, Mann-Whitney test and Spearman's correlation with a significance level of 5%.

RESULTS

The PCA group presented significantly lower right and left 2D:4D (P=0.001 and P=0.002, respectively) in comparison to healthy controls, but DR-L were not significantly different between groups (P=0.589). In addition, digit ratios were not correlated to Gleason score for either hand or in DR-L.

CONCLUSIONS

2D:4D seems to be a marker for screening patients for prostate cancer in an admixed population, as males with prostate cancer present lower 2D:4D than healthy subjects. On the other hand, 2D:4D does not appear to be associated with the severity of prostate cancer.

CTCF negatively regulates HOXA10 expression in breast cancer cells

HOX genes not only play important roles in defining body patterning during embryonic development, but also control numerous cellular events in adult cells. Deregulated HOX gene expression in different cancers including breast cancer is now increasingly being reported. Given that human HOXA cluster is marked with several CTCF binding sites, we investigated whether the presence of CTCF is associated directly with expression of HOXA genes in breast cancer cells. Several HOX genes, such as HOXA4, HOXA5 and HOXA10, were deregulated by CTCF overexpression and knockdown in MCF-7 cells. Among these genes, HOXA10 is an emerging tumor suppressor for its role in activation of p53 and in countering tumorigenesis in breast cancer. Here we provided evidences that CTCF functions as a negative regulator of HOXA10 in breast cancer cells. The putative promoter region of HOXA10 lies between 5.3 and 6.1 kb upstream of its start codon and its promoter activity was negatively regulated by CTCF. Together with in-silico analysis and in vitro mutation assay we identified a 20 bp CTCF binding motif flanking with core promoter element of HOXA10. HOXA10 promoter region was kept inactivated by maintaining H3K27me3 inactivation marks in the presence of CTCF. Epigenetic silencing of HOXA10 by CTCF in breast cancer cells may contribute towards tumorigenesis by decreasing apoptosis and promoting metastasis.

RNA Amplification Protocol Leads to Biased Polymerase Chain Reaction Results Especially for Low-Copy Transcripts of Human Bone Marrow-Derived Stromal Cells

The amplification of RNA is becoming increasingly important, as often only limited amounts of cells are available for gene expression analysis. In this study, the gene expression profile of the 39 human homeobox (HOX) genes was analyzed in bone marrow-derived multipotent stromal cells (BM-MSCs) by reverse transcription (RT-) and quantitative polymerase chain reaction (qPCR). For further unlimited gene expression analysis, Whole Transcriptome Amplification (WTA) was used to amplify RNA from human BM-MSCs. However, WTA led to biased RT- and qPCR results, and even non-detectability of HOX transcripts compared to non-amplified BM-MSC samples which instead revealed transcription. It is important to note that the same RNA of the respective human BM-MSC line was used for normal cDNA synthesis by standard reverse transcription (non-amplified RT samples) and for cDNA synthesis by WTA (amplified WTA samples). On this account, the different RT- and qPCR results were unexpected applying WTA. The significantly reduced detection of HOX transcripts after WTA has been demonstrated for numerous BM-MSC lines (n = 26) by RT-PCR analysis. Furthermore, undetectable HOX transcripts meaning HOX transcripts of human BM-MSCs that were detected after normal cDNA synthesis, but were no longer detectable after WTA, were consistently observed by qPCR analysis. Finally, qPCR experiments revealed a possible explanation for the differences between amplified and non-amplified BM-MSC samples: an inverse correlation between the biased qPCR results and the low expression level of the respective HOX gene. The PCR analysis of high-copy transcripts like GAPDH or RPL13A revealed unchanged qPCR results after WTA compared to corresponding non-amplified BM-MSC samples. In contrast, WTA led to biased qPCR results for medium-copy HOX transcripts, and even non-detectability of low-copy HOX transcripts of human BM-MSCs resulting in false negative RT- and qPCR data applying WTA.

Identification of several potential chromatin binding sites of HOXB7 and its downstream target genes in breast cancer

HOXB7 encodes a transcription factor that is overexpressed in a number of cancers and encompasses many oncogenic functions. Previous results have shown it to promote cell proliferation, angiogenesis, epithelial–mesenchymal transition, DNA repair and cell survival. Because of its role in many cancers and tumorigenic processes, HOXB7 has been suggested to be a potential drug target. However, HOXB7 binding sites on chromatin and its targets are poorly known. The aim of our study was to identify HOXB7 binding sites on breast cancer cell chromatin and to delineate direct target genes located nearby these binding sites. We found 1,504 HOXB7 chromatin binding sites in BT‐474 breast cancer cell line that overexpresses HOXB7. Seventeen selected binding sites were validated by ChIP‐qPCR in several breast cancer cell lines. Furthermore, we analyzed expression of a large number of genes located nearby HOXB7 binding sites and found several new direct targets, such as CTNND2 and SCGB1D2. Identification of HOXB7 chromatin binding sites and target genes is essential to understand better the role of HOXB7 in breast cancer and mechanisms by which it regulates tumorigenic processes.

What's new?

The transcription factor HOXB7 is overexpressed in various cancers, but it's not yet known just which genes HOXB7 activates. How does it influence cancer on a molecular level? This study found 1500 sequences where HOXB7 binds the chromatin in breast cancer cells. They went on to identify several potential target genes near the HOXB7 binding sites. Not only will finding these genes help explain how HOXB7 overexpression promotes tumor growth, it will help understand what side effects might result from hindering HOXB7 expression.

Overexpression of HOXA13 as a potential marker for diagnosis and poor prognosis of hepatocellular carcinoma

HOXA13 is a member of homeobox genes that encode transcription factors regulating embryonic development and cell fate. Abnormal HOXA13 expression was reported in hepatocellular carcinoma (HCC), but its correlation with tumor angiogenesis and prognosis still remain unclear. This study was aimed to uncover the expression, diagnostic and prognostic significance of HOXA13 in HCC. Immunohistochemistry was performed to detect HOXA13 expression in HCC and corresponding paracarcinomatous tissues from 90 patients. Enzyme-linked immunosorbent assay was used to detect serum HOXA13 in 90 HCC patients and 20 healthy volunteers. Receiver operating characteristics was analyzed to calculate diagnostic accuracy of serum HOXA13, alpha-fetoprotein (AFP) and their combination. Immunoreactivity of HOXA13 was detected in 72.2% of HCC, and 12.2% of adjacent non-cancerous samples. HOXA13 expression was significantly associated with tumor size, microvascular invasion, pathological grade, tumor capsula status, AFP level, tumor-node-metastasis stage and positively correlated with VEGF (p < 0.001) and microvessel density (p < 0.001). The combination of serum HOXA13 and AFP had a markedly higher area under the curve than HOXA13 alone. HOXA13 expression was associated with unfavorable overall survival (OS) (p < 0.001) and disease-free survival (DFS) (p < 0.001). Multivariate analysis indicated that patients with HOXA13-expressing tumors had a significantly shorter OS (p = 0.030) and DFS (p = 0.005) than those with HOXA13-negative tumors. Thus, HOXA13 expression possibly plays an important role in tumor angiogenesis, progression and prognosis of HCC. Moreover, we demonstrate that serum HOXA13 may serve as a biomarker for early HCC diagnosing and predicting outcome.

Transcriptional profiling of HOXA9-regulated genes in human glioblastoma cell models

The data here described pertain to the article by Pojo et al. (2015) [10] titled “A transcriptomic signature mediated by HOXA9 promotes human glioblastoma initiation, aggressiveness and resistance to temozolomide” (Pojoet al., 2015 [10]). HOX genes are part of the homeobox gene family, which encodes transcription factors crucial during embryonic development (Grier et al., 2005; Pearson et al., 2005 [6,9]) and also in post developmental regulation(Neville et al., 2002; Yamamoto et al., 2003; Takahashi et al., 2004;Morgan 2006 [8,14,13,7]). Alterations interfering with the regulation of these genes may lead to tumorigenesis in adults. Due to their contributions in the control of important cellular processes, the deregulation of HOX genes is ultimately correlated with cancer treatment failure and patients' poor prognosis (Golub et al., 1999; Abdel-Fattah et al., 2006 [5,1]; Costa et al.,2010 [4]; Pojo et al., 2015 [10]). Recently, our studies showed that HOXA9 overexpression is associated with poor prognosis in patients with glioblastoma (GBM), the most common and most malignant primary brain tumor. Mechanistically, HOXA9 is associated with resistance to chemotherapy and with pro-proliferative, pro invasive and anti-apoptotic features (Costa et al., 2010 [4]; Pojo et al., 2015 [10]) in GBM in vitro models. Since HOXA9 is a transcription factor, its target genes can be the true biological effectors of its aggressiveness. In this context, whole genome Agilent's microarrays were used to obtain the full transcriptome of HOXA9 in a variety of GBM cell models, including human immortalized astrocytes, established GBM cell lines, and GBM patient derived cell cultures. Here, we provide detailed methods, including experimental design and microarray data analyses,which can be accessed in Gene Expression Omnibus (GEO) under the accession number GSE56517. Additional interpretation of the data is included and supplemented in (Pojo et al., 2015 [10]).

Transcriptional dynamics of homeobox C11 gene in water buffalo bubalus bubalis

The Hox complex contains 39 genes clustered into four groups involved in cell differentiation and development. We cloned full-length sequence of Hoxc11 gene from water buffalo Bubalus bubalis, assessed its copy number, localized the same onto the chromosome 5, and studied its evolutionary conservation across the species. Northern hybridization of Hoxc11 showed a 2.2 kb band in the tissues analyzed. Real-Time PCR showed highest expression of Hoxc11 gene in lung followed by spleen, spermatozoa, and testis. Six interacting partners of this gene showed higher expression in spleen, lung, testis, and spermatozoa. During the early stages of development, Hoxc11 and its interacting partners both showed lower expression, which then became prominent during the age of 1-3 years, regressed drastically thereafter, and remained so until the animal's life time (∼ 20 years). The high expression of Hoxc11 and its interacting partners in spermatozoa and testis during the onset of puberty suggests its likely role in the differentiation of gonads and subsequent reproductive activities. Additional work on Hoxc11 especially, in the context of respiratory, immunological, and in/fertility in other species, including humans would be useful for establishing its broader biological significance towards the enrichment of functional and comparative genomics.

Bisphenol-A induces expression of HOXC6, an estrogen-regulated homeobox-containing gene associated with breast cancer

HOXC6 is a homeobox-containing gene associated with mammary gland development and is overexpressed in variety of cancers including breast and prostate cancers. Here, we have examined the expression of HOXC6 in breast cancer tissue, investigated its transcriptional regulation via estradiol (E2) and bisphenol-A (BPA, an estrogenic endocrine disruptor) in vitro and in vivo. We observed that HOXC6 is differentially over-expressed in breast cancer tissue. E2 induces HOXC6 expression in cultured breast cancer cells and in mammary glands of Sprague Dawley rats. HOXC6 expression is also induced upon exposure to BPA both in vitro and in vivo. Estrogen-receptor-alpha (ERα) and ER-coregulators such as MLL-histone methylases are bound to the HOXC6 promoter upon exposure to E2 or BPA and that resulted in increased histone H3K4-trimethylation, histone acetylation, and recruitment of RNA polymerase II at the HOXC6 promoter. HOXC6 overexpression induces expression of tumor growth factors and facilitates growth 3D-colony formation, indicating its potential roles in tumor growth. Our studies demonstrate that HOXC6, which is a critical player in mammary gland development, is upregulated in multiple cases of breast cancer, and is transcriptionally regulated by E2 and BPA, in vitro and in vivo.

miR-142-3p down-regulation contributes to thyroid follicular tumorigenesis by targeting ASH1L and MLL1

CONTEXT

A previous micro-RNA expression profile of thyroid follicular adenomas identified miR-142 precursor among the miRNAs downregulated in the neoplastic tissues compared to normal thyroid gland.

OBJECTIVE

The aim of this work has been to assess the expression of miR-142-3p in a large panel of follicular thyroid adenomas and carcinomas and evaluate its effect on thyroid cell proliferation and target expression.

DESIGN

The expression of miR-142-3p was analyzed by qRT-PCR in thyroid follicular adenomas and carcinomas, compared to normal thyroids. MiR-142-3p expression was restored in WRO cells and the effects on cell proliferation and target expression were evaluated.

RESULTS

Here we show that miR-142-3p is downregulated in FTAs, FTCs, and FVPTCs. MiR-142-3p was demonstrated to reduce the proliferation rate of WRO and FTC133 cells, supporting its tumor suppressor role in thyroid cancerogenesis. Moreover, this microRNA was able to downregulate the expression of ASH1L and MLL1, by direct and indirect mechanisms, respectively. Consistently, an inverse correlation between miR-142-3p expression and ASH1L and MLL1 proteins was found in thyroid follicular adenomas and carcinomas. ASH1L and MLL1, which belong to the Trithorax group (TrxG) proteins and are major regulators of Homeobox gene expression, maintain active target gene transcription by histone 3 lysine 4 methylation. Interestingly, we found that FTCs and FTC cell lines express tumor specific, shorter forms of the two proteins. The capability of miR-142-3p to modulate the levels of these tumor-associated forms and to reactivate thyroid-specific Hox gene expression, likely contributes to its tumor suppressive function.

CONCLUSIONS

These data demonstrate that miR-142-3p downregulation has a role in thyroid tumorigenesis, by regulating ASH1L and MLL1.

Homeobox gene expression in acute myeloid leukemia is linked to typical underlying molecular aberrations

Background

Although distinct patterns of homeobox (HOX) gene expression have been described in defined cytogenetic and molecular subsets of patients with acute myeloid leukemia (AML), it is unknown whether these patterns are the direct result of transcriptional alterations or rather represent the differentiation stage of the leukemic cell.

Method

To address this question, we used qPCR to analyze mRNA expression of HOXA and HOXB genes in bone marrow (BM) samples of 46 patients with AML and sorted subpopulations of healthy BM cells. These various stages of myeloid differentiation represent matched counterparts of morphological subgroups of AML. To further study the transcriptional alterations of HOX genes in hematopoiesis, we also analyzed gene expression of epigenetic modifiers in the subpopluations of healthy BM and leukemic cells.

Results

Unsupervised hierarchical clustering divided the AMLs into five clusters characterized by the presence of prevalent molecular genetic aberrations. Notably, the impact of genotype on HOX gene expression was significantly more pronounced than that of the differentiation stage of the blasts. This driving role of molecular aberrations was best exemplified by the repressive effect of the PML-RARa fusion gene on HOX gene expression, regardless of the presence of the FLT3/ITD mutation. Furthermore, HOX gene expression was positively correlated with mRNA levels of histone demethylases (JMJD3 and UTX) and negatively correlated with gene expression of DNA methyltranferases. No such relationships were observed in subpopulations of healthy BM cells.

Conclusion

Our results demonstrate that specific molecular genetic aberrations, rather than differentiation per se, underlie the observed differences in HOX gene expression in AML. Moreover, the observed correlations between epigenetic modifiers and HOX ex pression that are specific to malignant hematopoiesis, suggest their potential causal relationships.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-014-0094-0) contains supplementary material, which is available to authorized users.