HOXA5-induced apoptosis in breast cancer cells is mediated by caspases 2 and 8

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.

Exploring the regulatory interactions between mutated genes and homeobox genes in the head and neck cancer progression

OBJECTIVE

Understanding the regulatory role of homeobox (HOX) and mutated genes in the progression of head and neck cancers is essential, although their interaction remains elusive. This study aims to decipher the critical regulation of mutation driven effects on homeobox genes to enhance our understanding of head and neck cancer progression.

METHODS

Genomic mutation data from The Cancer Genome Atlas-Head and Neck Squamous Cell Carcinoma were analyzed using VarScan2 for somatic variant detection. Mutational clustering, driver mutation identification, and cancer signaling pathway analysis were performed using the OncodriveCLUST method. Harmonizome datasets were retrieved to identify critical cancer driver genes affecting HOX genes. The effects of HPV infection on HOX and mutated genes were assessed using the oncoviral database. Altered pathway activity due to the effects of cancer drivers on HOX genes was analyzed with Gene Set Cancer Analysis. Functional enrichment analysis of gene ontology biological processes and molecular functions was conducted using the ClusterProfiler R package.

RESULTS

Significant alterations in HOX genes were observed in head and neck cancer cohorts with mutated TP53, FAT1, and CDKN2A. HOX genes were identified as functionally downstream targets of TP53, signifying transcriptionally mediated regulation. The interaction between HOX genes and mutated TP53, FAT1, and CDKN2A dysregulated the epithelial-to-mesenchymal transition, cell cycle, and apoptosis pathways in head and neck cancer progression.

CONCLUSION

The interplay between cancer driver genes and HOX genes is pivotal in regulating the oncogenic processes underlying the pathogenesis of head and neck squamous cell carcinoma.

Role of homeobox d10 gene targeted signaling pathways in cancers

Homeobox D10 (HOXD10) is a transcription factor from the homeobox gene family that controls cell differentiation and morphogenesis throughout development.Due to their functional interaction, changes in HOXD10 gene expression might induce tumors. This narrative review focuses on how and why the dysregulation in the signaling pathways linked with HOXD10 contributes to the metastatic development of cancer. Organ development and tissue homeostasis need highly conserved homeotic transcription factors from homeobox (HOX) genes. Their dysregulation disrupts regulatory molecule action, causing tumors. The HOXD10 gene is upregulated in breast, gastric, hepatocellular, colorectal, bladder, cholangiocellular carcinoma and prostate cancer. Tumor signaling pathways are affected by HOXD10 gene expression changes. This study examines HOXD10-associated signaling pathway dysregulation, which may alter metastatic cancer signaling. In addition, the theoretical foundations that alter HOXD10-mediated therapeutic resistance in malignancies has been presented. New cancer therapy methods will be simpler to develop with the newly discovered knowledge. This review showed that HOXD10 may be a tumor suppressor gene and a new cancer treatment target signaling pathway.

Molecular mechanisms of multi-omic regulation in breast cancer

Breast cancer is a complex disease that is influenced by the concurrent influence of multiple genetic and environmental factors. Recent advances in genomics and other high throughput biomolecular techniques (-omics) have provided numerous insights into the molecular mechanisms underlying breast cancer development and progression. A number of these mechanisms involve multiple layers of regulation. In this review, we summarize the current knowledge on the role of multiple omics in the regulation of breast cancer, including the effects of DNA methylation, non-coding RNA, and other epigenomic changes. We comment on how integrating such diverse mechanisms is envisioned as key to a more comprehensive understanding of breast carcinogenesis and cancer biology with relevance to prognostics, diagnostics and therapeutics. We also discuss the potential clinical implications of these findings and highlight areas for future research. Overall, our understanding of the molecular mechanisms of multi-omic regulation in breast cancer is rapidly increasing and has the potential to inform the development of novel therapeutic approaches for this disease.

Deregulation of miR-375 Inhibits HOXA5 and Promotes Migration, Invasion, and Cell Proliferation in Breast Cancer

Breast cancer (BC) is a highly aggressive tumour and one of the women's leading causes of cancer-related deaths in worldwide. MiR-375 overexpressed in BC cells, and its biological relevance is largely unknown. Here in, we explored the function of miR-375 in BC. MicroRNA-375 targets were predicted by online target prediction tools and found that HOXA5 is one of the potential targets. MTT assay was employed to assess the effect of miR-375 on cell proliferation, where migration and invasion transwell assays were applied to detect cell migratory and invasive ability. Besides, relative expression of miR-375 and HOXA5 was measured in BC and HEK-293 cells, and its downstream gene target expressions were evaluated by qRT-PCR and western blot. In this study, we found that miR-375 expression was higher in BC cell lines than in the HEK-293 cell line, whereas HOXA5 expression was significantly lower. Our study showed that exogenous inhibition of miR-375 promoted HOXA5 expression; on the contrary, miR-375 mimics down-regulated HOXA5 expression level. Knockdown of miR-375 expression in BC cells reduces cell proliferation, migration, and invasion by inverse correlation expression of HOXA5. Our findings associated that miR-375 accelerated apoptosis evasion, proliferation, migration, and invasion by targeting HOXA5. In addition, nucleolin interferes in miR-375 biogenesis while silencing of nucleolin significantly reduced miR-375 expression and increased HOXA5 expression in BC. Thus, miR-375/HOXA5 axis may represent a potential therapeutic target for BC treatment.

Deciphering the molecular mechanism and crosstalk between Parkinson's disease and breast cancer through multi-omics and drug repurposing approach

Epidemiological studies indicate a higher occurrence of breast cancer (BRCA) in patients with Parkinson's disease. However, the exact molecular mechanism is still not precise. Herein, we tested the hypothesis that this inverse comorbidity result from shared genetic and molecular processes. We conducted an integrated omics analysis to identify the common gene signatures associated with PD and BRCA. Secondly, several dysregulated biological processes in both indications were analyzed by functional enrichment methods, and significant overlapping processes were identified. To establish common regulatory mechanisms, information about transcription factors and miRNAs associated with both the disorders was extracted. Finally, disease-specific gene expression signatures were compared through LINCS L1000 analysis to identify potential repurposing drugs for PD. The potential repurposed drug candidates were then correlated with PD-specific gene signatures by Cmap analysis. In conclusion, this study highlights the shared genes, biological pathways and regulatory signatures associated with PD and BRCA with an improved understanding of crosstalk involved. Additionally, the role of therapeutics was investigated in context with their comorbid associations. These findings could help to explain the complex molecular patterns of associations between PD and BRCA.

HOXA1, a breast cancer oncogene

More than 25 years ago, the first literature records mentioned HOXA1 expression in human breast cancer. A few years later, HOXA1 was confirmed as a proper oncogene in mammary tissue. In the following two decades, molecular data about the mode of action of the HOXA1 protein, the factors contributing to activate and maintain HOXA1 gene expression and the identity of its target genes have accumulated and provide a wider view on the association of this transcription factor to breast oncogenesis. Large-scale transcriptomic data gathered from wide cohorts of patients further allowed refining the relationship between breast cancer type and HOXA1 expression. Several recent reports have reviewed the connection between cancer hallmarks and the biology of HOX genes in general. Here we take HOXA1 as a paradigm and propose an extensive overview of the molecular data centered on this oncoprotein, from what its expression modulators, to the interactors contributing to its oncogenic activities, and to the pathways and genes it controls. The data converge to an intricate picture that answers questions on the multi-modality of its oncogene activities, point towards better understanding of breast cancer aetiology and thereby provides an appraisal for treatment opportunities.

HOXA5 inhibits adipocytes proliferation through transcriptional regulation of Ccne1 and blocking JAK2/STAT3 signaling pathway in mice

The highly regulated proliferation of adipocytes plays a momentous role in fat development and obesity. Hoxa5 is an important member of Hox family, its encoded protein is an important transcription factor related to development. And its differential expression in different adipose tissues seems to indicate that Hoxa5 may be involved in the regulation of adipocyte proliferation. In order to evaluate the regulation mechanism of Hoxa5 on adipocyte proliferation, we constructed a variety of Hoxa5 expression vectors in vivo and in vitro to explore its mechanism on adipocyte proliferation and its potential impact on obesity. We have observed that the overexpression of Hoxa5 strongly reduces cell counts, and Hoxa5 can inhibit cell proliferation and block cell cycle progression by regulating the expression of genes such as Cyclin E, Cycling D1 and p53. Most importantly, we demonstrated that Hoxa5 exerts its effect by regulating the signaling pathway of Janus kinase 2 (JAK2) signal transduction and transcription 3 (STAT3) activator, as well as binding to the promoter region of Ccne1 and inhibiting the transcription of Ccne1.This study provides an in-depth understanding of the potential molecular mechanism of Hoxa5 inhibiting adipocyte proliferation. Our results suggest the importance of Hoxa5 in the treatment of obesity.

Tetrahydrobiopterin and Its Multiple Roles in Neuropsychological Disorders

Tetrahydrobiopterin (BH4) is a multifunctional co-factor of various enzymes and a substantial amount of studies have shown BH4 as a key regulator in the synthesis of neurotransmitters such as serotonin, nor-epinephrine as well as dopamine. The imbalance of BH4 may affect neurotransmitter production which can lead to many abnormalities in CNS. This article reviews the role of BH4 in neurodegenerative and neurodevelopmental disorders. We focus on the therapeutic potential of BH4 in various brain diseases that involves neurotransmitters and attempt to address how the modulation of BH4 may provide a novel strategy in various neuropsychological conditions.

The Whole Blood DNA Methylation Patterns of Extrinsic Apoptotic Signaling Pathway Related Genes in Autoimmune Thyroiditis among Areas with Different Iodine Levels

Autoimmune thyroiditis (AIT) has a complex etiology and the susceptibility to it is determined by a combination of genetic and environmental factors, although these are not yet fully understood. The present research aimed to explore the DNA methylation patterns in whole blood of extrinsic apoptotic signaling pathway related genes in AIT among areas with different iodine levels. We selected the iodine-fortification areas (IFA), iodine-adequate areas (IAA) and water-based iodine-excess areas (IEA) from Shandong Province of China as survey sites. Totally 176 AIT cases and 176 controls were included. MethylTargetTM and QT-PCR technology were used to detect candidate genes' DNA methylation levels and mRNA expression levels, respectively. We found that DAPK1 DNA methylation levels in AIT cases (especially in female) were significantly higher than controls (t=2.7715, P=0.0059; t=2.4638, P=0.0143 in female). There were differences in DAPK1(t=2.5384, P=0.0121), TNFSF8(t=2.1667, P=0.0334) and TNFAIP8(t=2.5672, P=0.0121) genes methylation between cases and controls with different water iodine levels. The mRNA expression of DAPK1(t=4.329, P<0.001) and TNFAIP8(t=3.775, P<0.001) in the cases were increased. We identified the differences in the DNA methylation status of the extrinsic apoptotic signaling pathway related genes between AIT and controls and in different iodine levels areas. The results were verified at the mRNA level. The environmental iodine may affect DNA methylation to some extent.

Molecular implications of HOX genes targeting multiple signaling pathways in cancer

Homeobox (HOX) genes encode highly conserved homeotic transcription factors that play a crucial role in organogenesis and tissue homeostasis. Their deregulation impacts the function of several regulatory molecules contributing to tumor initiation and progression. A functional bridge exists between altered gene expression of individual HOX genes and tumorigenesis. This review focuses on how deregulation in the HOX-associated signaling pathways contributes to the metastatic progression in cancer. We discuss their functional significance, clinical implications and ascertain their role as a diagnostic and prognostic biomarker in the various cancer types. Besides, the mechanism of understanding the theoretical underpinning that affects HOX-mediated therapy resistance in cancers has been outlined. The knowledge gained shall pave the way for newer insights into the treatment of cancer.

Downstream of the HOX genes: explaining conflicting tumour suppressor and oncogenic functions in cancer

The HOX genes are a highly conserved group of transcription factors that have key roles in early development, but which are also highly expressed in most cancers. Many studies have found strong associative relationships between the expression of individual HOX genes in tumours and clinical parameters including survival. For the majority of HOX genes, high tumour expression levels seem to be associated with a worse outcome for patients, and in some cases this has been shown to result from the activation of pro-oncogenic genes and pathways. However, there are also many studies that indicate a tumour suppressor role for some HOX genes, sometimes with conclusions that contradict earlier work. In this review, we have attempted to clarify the role of HOX genes in cancer by focusing on their downstream targets as identified in studies that provide experimental evidence for their activation or repression. On this basis, the majority of HOX genes would appear to have a pro-oncogenic function, with the notable exception of HOXD10, which acts exclusively as a tumour suppressor. HOX proteins regulate a wide range of target genes involved in metastasis, cell death, proliferation, and angiogenesis, and activate key cell signalling pathways. Furthermore, for some functionally related targets, this regulation is achieved by a relatively small subgroup of HOX genes.

Homeobox Genes in Cancers: From Carcinogenesis to Recent Therapeutic Intervention

The homeobox (HOX) genes encoding an evolutionarily highly conserved family of homeodomain-containing transcriptional factors are essential for embryogenesis and tumorigenesis. HOX genes are involved in cell identity determination during early embryonic development and postnatal processes. The deregulation of HOX genes is closely associated with numerous human malignancies, highlighting the indispensable involvement in mortal cancer development. Since most HOX genes behave as oncogenes or tumor suppressors in human cancer, a better comprehension of their upstream regulators and downstream targets contributes to elucidating the function of HOX genes in cancer development. In addition, targeting HOX genes may imply therapeutic potential. Recently, novel therapies such as monoclonal antibodies targeting tyrosine receptor kinases, small molecular chemical inhibitors, and small interfering RNA strategies, are difficult to implement for targeting transcriptional factors on account of the dual function and pleiotropic nature of HOX genes-related molecular networks. This paper summarizes the current state of knowledge on the roles of HOX genes in human cancer and emphasizes the emerging importance of HOX genes as potential therapeutic targets to overcome the limitations of present cancer therapy.

Sex-Stratified Single-Cell RNA-Seq Analysis Identifies Sex-Specific and Cell Type-Specific Transcriptional Responses in Alzheimer's Disease Across Two Brain Regions

Alzheimer’s disease (AD) is a pervasive neurodegenerative disorder that disproportionately affects women. Since neural anatomy and disease pathophysiology differ by sex, investigating sex-specific mechanisms in AD pathophysiology can inform new therapeutic approaches for both sexes. Previous bulk human brain RNA sequencing studies have revealed sex differences in dysregulated molecular pathways related to energy production, neuronal function, and immune response; however, the sex differences in disease mechanisms are yet to be examined comprehensively on a single-cell level. We leveraged nearly 74,000 cells from human prefrontal and entorhinal cortex samples from the first two publicly available single-cell RNA sequencing AD datasets to perform a case versus control sex-stratified differential gene expression analysis and pathway network enrichment in a cell type-specific manner for each brain region. Our examination at the single-cell level revealed sex differences in AD prominently in glial cells of the prefrontal cortex. In the entorhinal cortex, we observed the same genes and networks to be perturbed in opposing directions between sexes in AD relative to healthy state. Our findings contribute to growing evidence of sex differences in AD-related transcriptomic changes, which can fuel the development of therapies that may prove more effective at reversing AD pathophysiology.

A prognostic score based on long-term survivor unique transcriptomic signatures predicts patient survival in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is known for its poor prognosis with few long-term survivors. This study aimed to establish a prognostic score using unique transcriptomic profiles of long-term survivors to be used as a patient selection tool for meaningful clinical intervention in PDAC. In TCGA PDAC cohort, 16 genes were significantly upregulated in the long-term survivor tumors. A prognostic score was established using these 16 genes by LASSO Cox regression, and PHKG1, HOXA4, ISL2, DMRT3 and TRA2A gene expressions were included in the score. The prognostic value was confirmed in both testing and validation cohorts. The characteristics of the high score tumor was investigated by bioinformatical approach. The high score tumor was associated with TP53 mutation but not with other commonly enhanced signaling pathways in PDAC. The high score tumor was associated with higher tumor mutational burden and unfavorable tumor microenvironment (TME), such as lower infiltration of CD8-positive T cells and dendritic cells, and less cell composition of mature blood vessels and fibroblasts. The high score tumor was also associated with enhanced cell proliferation and margin positivity after surgery. The impact of score component genes on the cell proliferation was investigated by in vitro experiments. Silencing of the score component genes promoted cell proliferation. In conclusion, the prognostic score predicted PDAC patient survival and was associated with cancer aggressiveness such as unfavorable TME and enhanced cell proliferation.

HOXA5 Is Recognized as a Prognostic-Related Biomarker and Promotes Glioma Progression Through Affecting Cell Cycle

Glioma is malignant tumor derives from glial cells in the central nervous system. High-grade glioma shows aggressive growth pattern, and conventional treatments, such as surgical removal and chemo-radiotherapy, archive limitation in the interference of this process. In this work, HOXA5, from the HOX family, was identified as a glioma cell proliferation-associated factor by investigating its feature in the TCGA and CGGA data set. High HOXA5 expression samples contain unfavorable clinical features of glioma, including IDH wild type, un-methylated MGMT status, non-codeletion 1p19q status, malignant molecular subtype. Survival analysis indicates that high HOXA5 expression samples are associated with worse clinical outcome. The CNVs and SNPs profile difference further confirmed the enrichment of glioma aggressive related biomarkers. In the meantime, the activation of DNA damage repair-related pathways and TP53-related pathways is also related to HOXA5 expression. In cell lines, U87MG and U251, by interfering HOXA5 expression significantly inhibit glioma progression and apoptosis, and cell cycle is arrested at the G2/M phase. Collectively, increased HOXA5 expression can promote glioma progression via affecting glioma cell proliferation.

Overexpression of HOXA10 promotes the growth and metastasis of nasopharyngeal carcinoma

Deregulation of HOX transcription factor family has frequently been observed in multiple human cancers; however, their role in nasopharyngeal carcinoma remains largely unclear. In the present study, we found that HOX gene family is consistently upregulated in nasopharyngeal carcinoma and identified HOXA10 as one of the mostly upregulated HOX genes. Importantly, we show that HOXA10 overexpression is associated with transcriptional activation of multiple oncogenes essential for nasopharyngeal carcinoma carcinogenesis, including S-phase kinase-associated protein 2 (SKP2), calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2), and matrix metalloproteinase 1 (MMP1). Mechanistically, the overexpression of SKP2 induces the degradation of cell cycle inhibitor p27, leading to rapid cell cycle progression and cell proliferation. The overexpression of CAMKK2 is associated with enhanced mTOR signaling activity to meet the increased demand for proteins synthesis in rapid growing nasopharyngeal carcinoma cells. Moreover, MMP1 overexpression facilitates nasopharyngeal carcinoma cell migration and invasion and contributes to cancer metastasis and progression. We thus concluded that HOXA10 overexpression promotes the growth and metastasis of nasopharyngeal carcinoma by transcriptionally activating various oncogenic pathways.

HOXA5 confers tamoxifen resistance via the PI3K/AKT signaling pathway in ER-positive breast cancer

Tamoxifen is a commonly used drug to treat estrogen receptor-positive patients with breast cancer. Despite the outstanding efficacy of tamoxifen, approximately one-third of patients develop resistance toward it, thereby presenting a therapeutic challenge. HOX genes may be involved in the acquisition of tamoxifen resistance. In this study, we identified HOXA5, a member of the HOX gene family, as a marker of tamoxifen resistance. Using ChIP assay, we found that HOXA5 expression was significantly overexpressed in tamoxifen-resistant MCF7 (TAMR) breast cancer cells because of reduced H3K27me3 binding. HOXA5 upregulation resulted in activation of the PI3K/AKT signaling cascade, which in turn, led to p53 and p21 reduction, ultimately making the TAMR cells less apoptotic. Furthermore, elevated HOXA5 expression resulted in breast cancer cells acquiring more mesenchymal-like and stem cell traits associated with aggressive breast cancer phenotypes. In conclusion, our results delineate a mechanism by which HOXA5 promotes tumorigenesis, cancer progression, and tamoxifen resistance in breast cancer cells.

New insights in the clinical implication of HOXA5 as prognostic biomarker in patients with colorectal cancer

BACKGROUND

Homeobox A5 (HOXA5) is a member of the HOX protein family which is involved in several carcinogenesis pathways, and is dysregulated in many cancer types. However, its expression and function in human colorectal cancer (CRC) is still largely unknown.

OBJECTIVE

This study aimed to evaluate HOXA5 expression in Tunisian patients with CRC in order to define new potential biomarker.

METHODS

An immunohistochemical labeling using an HOXA5 antibody was performed on 85 formalin fixed paraffin embedded specimens from patients with CRC. Six normal colon mucosa cases were used as controls.

RESULTS

HOXA5 expression showed a cytoplasmic staining in both tumor and stromal/endothelial cells. Loss or low HOXA5 expression was seen in tumor cells in 74/85 cases (87.06%) and in stromal/endothelial cells, in 77/85 (90.59%). In control group of normal colon mucosa HOXA5 was moderately expressed in all the cases. The abnormal expression, was significantly associated to lymph nodes metastasis in tumor cells (p= 0.043) and in stromal/endothelial cells (p= 0.024).

CONCLUSION

HOXA5 immunostaining results suggest the valuable role of this protein in colorectal carcinogenesis. Moreover, the association of lymph node metastasis to HOXA5 abnormal expression underlies its crucial role in colorectal cancer dissemination and prognosis.

HOXA5 counteracts the function of pathological scar-derived fibroblasts by partially activating p53 signaling

The inactivation of p53 can lead to the formation of pathological scars, including hypertrophic scars and keloids. HOXA5 has been reported to be a critical transcription factor in the p53 pathway in cancers. However, whether HOXA5 also plays a role in pathological scar progression through activating p53 signaling remains unknown. In this study, we first demonstrated that HOXA5 overexpression in hypertrophic scar-or keloids-derived fibroblasts decreased cell proliferation, migration and collagen synthesis, whereas increased cell apoptosis. Furthermore, the results of luciferase activity assays and ChIP PCR assays indicated that HOXA5 transactivated p53 by binding to the ATTA-rich core motif in the p53 promoter. HOXA5 also increased the levels of p21 and Mdm2, which are downstream targets of p53. Interestingly, silencing p53 in these pathological scar-derived fibroblasts partially attenuated HOXA5-mediated growth inhibition effect and HOXA5-induced apoptosis. In addition, 9-cis-retinoic acid augmented the expression of HOXA5 and promoted the effects of HOXA5 on pathological scar-derived fibroblasts, and these effects could be suppressed by HOXA5 knockdown. Thus, our study reveals a role of HOXA5 in mediating the cellular processes of pathological scar-derived fibroblasts by transcriptionally activating the p53 signaling pathway, and 9-cis-retinoic acid may be a potential therapy for pathological scars.

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.

Phosphorylation of Msx1 promotes cell proliferation through the Fgf9/18-MAPK signaling pathway during embryonic limb development

Msh homeobox (Msx) is a subclass of homeobox transcriptional regulators that control cell lineage development, including the early stage of vertebrate limb development, although the underlying mechanisms are not clear. Here, we demonstrate that Msx1 promotes the proliferation of myoblasts and mesenchymal stem cells (MSCs) by enhancing mitogen-activated protein kinase (MAPK) signaling. Msx1 directly binds to and upregulates the expression of fibroblast growth factor 9 (Fgf9) and Fgf18. Accordingly, knockdown or antibody neutralization of Fgf9/18 inhibits Msx1-activated extracellular signal-regulated kinase 1/2 (Erk1/2) phosphorylation. Mechanistically, we determined that the phosphorylation of Msx1 at Ser136 is critical for enhancing Fgf9 and Fgf18 expression and cell proliferation, and cyclin-dependent kinase 1 (CDK1) is apparently responsible for Ser136 phosphorylation. Furthermore, mesenchymal deletion of Msx1/2 results in decreased Fgf9 and Fgf18 expression and Erk1/2 phosphorylation, which leads to serious defects in limb development in mice. Collectively, our findings established an important function of the Msx1-Fgf-MAPK signaling axis in promoting cell proliferation, thus providing a new mechanistic insight into limb development.

HOX genes and the NF-κB pathway: A convergence of developmental biology, inflammation and cancer biology

The roles of HOX transcription factors as oncogenes and tumor suppressor genes, and the NF-KB pathway in chronic inflammation, both leading to cancer are well-established. HOX transcription factors are members of an evolutionarily conserved family of proteins required for anteroposterior body axis patterning during embryonic development, and are often dysregulated in cancer. The NF-KB pathway aids inflammation and immunity but it is also important during embryonic development. It is frequently activated in both solid and hematological malignancies. NF-KB and HOX proteins can influence each other through mutual transcriptional regulation, protein-protein interactions, and regulation of upstream and downstream interactors. These interactions have important implications both in homeostasis and in disease. In this review, we summarize the role of HOX proteins in regulating inflammation in homeostasis and disease- with a particular emphasis on cancer. We also describe the relationship between HOX genes and the NF-KB pathway, and discuss potential therapeutic strategies.

Context-dependent HOX transcription factor function in health and disease

During animal development, HOX transcription factors determine the fate of developing tissues to generate diverse organs and appendages. The power of these proteins is striking: mis-expressing a HOX protein causes homeotic transformation of one body part into another. During development, HOX proteins interpret their cellular context through protein interactions, alternative splicing, and post-translational modifications to regulate cell proliferation, cell death, cell migration, cell differentiation, and angiogenesis. Although mutation and/or mis-expression of HOX proteins during development can be lethal, changes in HOX proteins that do not pattern vital organs can result in survivable malformations. In adults, mutation and/or mis-expression of HOX proteins disrupts their gene regulatory networks, deregulating cell behaviors and leading to arthritis and cancer. On the molecular level, HOX proteins are composed of DNA binding homeodomain, and large regions of unstructured, or intrinsically disordered, protein sequence. The primary roles of HOX proteins in arthritis and cancer suggest that mutations associated with these diseases in both the structured and disordered regions of HOX proteins can have substantial functional effects. These insights lead to new questions critical for understanding and manipulating HOX function in physiological and pathological conditions.

The Role of Caspase-2 in Regulating Cell Fate

Caspase-2 is the most evolutionarily conserved member of the mammalian caspase family and has been implicated in both apoptotic and non-apoptotic signaling pathways, including tumor suppression, cell cycle regulation, and DNA repair. A myriad of signaling molecules is associated with the tight regulation of caspase-2 to mediate multiple cellular processes far beyond apoptotic cell death. This review provides a comprehensive overview of the literature pertaining to possible sophisticated molecular mechanisms underlying the multifaceted process of caspase-2 activation and to highlight its interplay between factors that promote or suppress apoptosis in a complicated regulatory network that determines the fate of a cell from its birth and throughout its life.

MicroRNA-181d-5p-Containing Exosomes Derived from CAFs Promote EMT by Regulating CDX2/HOXA5 in Breast Cancer

Recently, novel mechanisms underlying the pro-tumorigenic effects of cancer-associated fibroblasts (CAFs) have been identified in several cancers, including breast cancer. CAFs can secrete exosomes that are loaded with proteins, lipids, and RNAs to affect tumor microenvironment. Herein, we identify CAF-derived exosomes that can transfer miR-181d-5p to enhance the aggressiveness of breast cancer. Cancerous tissues and matched paracancerous tissues were surgically resected from 122 patients with breast cancer. Chromatin immunoprecipitation (ChIP) and dual luciferase reporter assays were employed to identify interaction between homeobox A5 (HOXA5) and caudal-related homeobox 2 (CDX2), as well as between CDX2 and miR-181d-5p, respectively. Human breast cancer Michigan Cancer Foundation-7 (MCF-7) cells were cocultured with CAF-derived exosomes. 5-Ethynyl-2'-deoxyuridine (EdU) assay, TUNEL staining, Transwell invasion assays, and scratch tests were carried out to evaluate MCF-7 cell functions. Nude mice bearing xenografted MCF-7 cells were injected with CAF-derived exosomes, and the tumor formation was evaluated. HOXA5 expressed at a poor level in breast cancer tissues, and its overexpression retarded MCF-7 cell proliferation, invasion, migration, and epithelial-mesenchymal transition (EMT) and facilitated its apoptosis in vitro. miR-181d-5p targets CDX2, a transcription factor binding to HOXA5 promoter. Coculture of CAFs and MCF-7 cells showed that CAFs prolonged proliferation and antagonized apoptosis of MCF-7 cells via release of exosomes. Coculture of MCF-7 cells and exosomes derived from CAFs identified miR-181d-5p as a mediator of the exosomal effects on MCF-7 cells, in part, via downregulation of CDX2 and HOXA5. CAF-derived exosomes containing miR-181d-5p promoted the tumor growth of nude mice bearing xenografted MCF-7 cells. In conclusion, exosomal miR-181d-5p plays a key role in CAF-mediated effects on tumor environment in breast cancer, likely via CDX2 and HOXA5.

Assessment of Expression of Homeobox A5 in Endometrial Cancer on the mRNA and Protein Level

BACKGROUND

Endometrial cancer is one of the most common gynecological cancer in the developed countries and occurs mainly in postmenopausal women. Angiogenesis is important for cancer formation as it provides nutrients for growing tumor mass. Most tumors do not show detectable Homeobox A5 (HOXA5 level), suggesting its potential role as a cancer suppressor. It was demonstrated that HOXA5 is involved in the progression of various types of cancer and the loss of its expression correlates with higher pathological grade and poorer outcome.

OBJECTIVE

The aim of the study was to evaluate HOXA5 expression at transcriptome and protein levels.

MATERIALS AND METHODS

The study enrolled 45 women diagnosed with endometrial cancer and 15 without neoplastic changes. The histopathological examination allowed us to divide cancer tissue samples according to the degree of histological differentiation: G1, 17; G2, 15; G3, 13. The expression of the HOXA5 protein was determined by immunohistochemistry. Microarray and RT-qPCR techniques were used to assess HOXA5 expression at the mRNA level.

RESULTS

The reaction to the HOXA5 protein was only visible in glandular cells in G1 endometrial cancer and was lower compared to the control. In grades 2 and 3, reactions were noted at the limit of the method's sensitivity. In addition, reduced HOXA5 expression was observed at the transcriptome level.

CONCLUSION

HOXA5 may become a potential complementary molecular marker, allowing early detection of neoplastic changes in the endometrium. It also seems that detection of HOXA5 at the mRNA and protein levels may be helpful in improving the accuracy of diagnosis and planning effective oncological therapy.

microRNA-26a-5p Promotes Proliferation and Migration of Osteosarcoma Cells by Targeting HOXA5 in vitro and in vivo

Background

Osteosarcoma is the most common primary malignant tumor of bone. However, the underlying pathogenic mechanisms are still unclear. miR-26a was an endogenous non-coding small RNAs that have been showed to play a critical role in regulating varieties of biological and pathological processes. In this study, we will investigate the function of miR-26a-5p in osteosarcoma cells.

Methods

In this study, we explored the role of miR-26a-5p in osteosarcoma cell lines using qPCR, detected the proliferation, cell cycle and cell migration by CCK-8, PI and transwell.

Results

We found that compared with noncancerous cells, miR-26a-5p was highly expressed in osteosarcoma cell lines, especially in U2OS cells. Overexpression of miR-26a-5p promotes cell proliferation, cell cycle, and cell migration, but inhibits cell apoptosis. But down-regulation of miR-26a-5p in U2OS cells exhibits opposite effects. We also confirmed that miR-26a-5p directly targets HOXA5 in U2OS cells. Overexpression of HOXA5 reversed the effect of miR-26a-5p on cell proliferation, migration, and apoptosis. Besides, we showed in that knock-down of miR-26a-5p or overexpression of HOXA5 increased cell sensitivity to chemotherapeutic drug paclitaxel.

Conclusion

These findings indicate that highly expressed miR-26a-5p in osteosarcoma cells, and promotes proliferation and migration, but inhibits apoptosis of osteosarcoma cells by targeting HOXA5 which suggest that miR-26a-5p could serve as a novel therapeutic target for osteosarcoma.

Master Regulators of Signaling Pathways: An Application to the Analysis of Gene Regulation in Breast Cancer

Analysis of gene regulatory networks allows the identification of master transcriptional factors that control specific groups of genes. In this work, we inferred a gene regulatory network from a large dataset of breast cancer samples to identify the master transcriptional factors that control the genes within signal transduction pathways. The focus in a particular subset of relevant genes constitutes an extension of the original Master Regulator Inference Algorithm (MARINa) analysis. This modified version of MARINa utilizes a restricted molecular signature containing genes from the 25 human pathways in KEGG's signal transduction category. Our breast cancer RNAseq expression dataset consists of 881 samples comprising tumors and normal mammary gland tissue. The top 10 master transcriptional factors found to regulate signal transduction pathways in breast cancer we identified are: TSHZ2, HOXA2, MEIS2, HOXA3, HAND2, HOXA5, TBX18, PEG3, GLI2, and CLOCK. The functional enrichment of the regulons of these master transcriptional factors showed an important proportion of processes related to morphogenesis. Our results suggest that, as part of the aberrant regulation of signaling pathways in breast cancer, pathways similar to the regulation of cell differentiation, cardiovascular system development, and vasculature development may be dysregulated and co-opted in favor of tumor development through the action of these transcription factors.

HOX family transcription factors: Related signaling pathways and post-translational modifications in cancer

HOX family transcription factors belong to a highly conserved subgroup of the homeobox superfamily that determines cellular fates in embryonic morphogenesis and the maintenance of adult tissue architecture. HOX family transcription factors play key roles in numerous cellular processes including cell growth, differentiation, apoptosis, motility, and angiogenesis. As tumor promoters or suppressors HOX family members have been reported to be closely related with a variety of cancers. They closely regulate tumor initiation and growth, invasion and metastasis, angiogenesis, anti-cancer drug resistance and stem cell origin. Here, we firstly described the pivotal roles of HOX transcription factors in tumorigenesis. Then, we summarized the main signaling pathways regulated by HOX transcription factors, including Wnt/β-catenin, transforming growth factor β, mitogen-activated protein kinase, phosphoinositide 3-kinase/Akt, and nuclear factor-κB signalings. Finally, we outlined the important post-translational modifications of HOX transcription factors and their regulation in cancers. Future research directions on the HOX transcription factors are also discussed.

HOX genes as transcriptional and epigenetic regulators during tumorigenesis and their value as therapeutic targets

Several HOX genes are aberrantly expressed in a wide range of cancers interfering with their development and resistance to treatment. This seems to be often caused by alterations in the methylation profiles of their promoters. The role of HOX gene products in cancer is highly 'tissue specific', relying ultimately on their ability to regulate oncogenes or tumor-suppressor genes, directly as transcriptional regulators or indirectly interfering with the levels of epigenetic regulators. Nowadays, different strategies have been tested the use of HOX genes as therapeutic targets for cancer diagnosis and treatment. Here, we trace the history of the research concerning the involvement of HOX genes in cancer, their connection with epigenetic regulation and their potential use as therapeutic targets.

The Role of HOX Transcription Factors in Cancer Predisposition and Progression

Homeobox (HOX) transcription factors, encoded by a subset of homeodomain superfamily genes, play pivotal roles in many aspects of cellular physiology, embryonic development, and tissue homeostasis. Findings over the past decade have revealed that mutations in HOX genes can lead to increased cancer predisposition, and HOX genes might mediate the effect of many other cancer susceptibility factors by recognizing or executing altered genetic information. Remarkably, several lines of evidence highlight the interplays between HOX transcription factors and cancer risk loci discovered by genome-wide association studies, thereby gaining molecular and biological insight into cancer etiology. In addition, deregulated HOX gene expression impacts various aspects of cancer progression, including tumor angiogenesis, cell autophagy, proliferation, apoptosis, tumor cell migration, and metabolism. In this review, we will discuss the fundamental roles of HOX genes in cancer susceptibility and progression, highlighting multiple molecular mechanisms of HOX involved gene misregulation, as well as their potential implications in clinical practice.

HOXA5 inhibits tumor growth of gastric cancer under the regulation of microRNA-196a

Homeobox A5 (HOXA5) is a member of the HOX protein family which were implicated in serval critical process and was cancer-specific dysregulated in human cancers. However, its expression and function in human gastric cancer (GC) was still largely unknown. In this study, we confirmed for the first time that HOXA5 mRNA and protein was down-regulated in GC tissues and cell lines. Clinical data showed that low HOXA5 was significantly associated poor prognostic features, including large tumor size and advanced TNM stage. For 5-year survival, HOXA5 served as a potential prognostic marker of GC patients. Notably, HOXA5 inhibited cell viability, colony formation, proliferation, cell cycle progression and promoted apoptosis in vitro and in vivo. Furthermore, we demonstrated that HOXA5 expression was regulated by miR-196a. In GC tissues, miR-196a has an inverse correlation with HOXA5 expression. Conclusively, our results demonstrated that HOXA5 functions as a tumor suppressor in regulating tumor growth of GC under regulation of miR-196a, supporting its potential utility as a therapeutic target for GC.

Increased HOXA5 expression provides a selective advantage for gain of whole chromosome 7 in IDH wild-type glioblastoma

Cimino et al. developed an unbiased bioinformatics approach that identified homeobox A5 (HOXA5) as a gene whose expression correlated with gain of chromosome 7 and a more aggressive phenotype of the resulting glioma. HOXA5 overexpression promoted cellular proliferation and potentiated radioresistance.

Glioblastoma is the most frequently occurring and invariably fatal primary brain tumor in adults. The vast majority of glioblastomas is characterized by chromosomal copy number alterations, including gain of whole chromosome 7 and loss of whole chromosome 10. Gain of whole chromosome 7 is an early event in gliomagenesis that occurs in proneural-like precursor cells, which give rise to all isocitrate dehydrogenase (IDH) wild-type glioblastoma transcriptional subtypes. Platelet-derived growth factor A (PDGFA) is one gene on chromosome 7 known to drive gliomagenesis, but, given its location near the end of 7p, there are likely several other genes located along chromosome 7 that select for its increased whole-chromosome copy number within glioblastoma cells. To identify other potential genes that could select for gain of whole chromosome 7, we developed an unbiased bioinformatics approach that identified homeobox A5 (HOXA5) as a gene whose expression correlated with gain of chromosome 7 and a more aggressive phenotype of the resulting glioma. High expression of HOXA5 in glioblastoma was associated with a proneural gene expression pattern and decreased overall survival in both human proneural and PDGF-driven mouse glioblastoma. Furthermore, HOXA5 overexpression promoted cellular proliferation and potentiated radioresistance. We also found enrichment of HOXA5 expression in recurrent human and mouse glioblastoma at first recurrence after radiotherapy. Overall, this study implicates HOXA5 as a chromosome 7-associated gene-level locus that promotes selection for gain of whole chromosome 7 and an aggressive phenotype in glioblastoma.

Oncogenomics of c-Myc transgenic mice reveal novel regulators of extracellular signaling, angiogenesis and invasion with clinical significance for human lung adenocarcinoma

The c-Myc transcription factor is frequently deregulated in cancers. To search for disease diagnostic and druggable targets a transgenic lung cancer disease model was investigated. Oncogenomics identified c-Myc target genes in lung tumors. These were validated by RT-PCR, Western Blotting, EMSA assays and ChIP-seq data retrieved from public sources. Gene reporter and ChIP assays verified functional importance of c-Myc binding sites. The clinical significance was established by RT-qPCR in tumor and matched healthy control tissues, by RNA-seq data retrieved from the TCGA Consortium and by immunohistochemistry recovered from the Human Protein Atlas repository. In transgenic lung tumors 25 novel candidate genes were identified. These code for growth factors, Wnt/β-catenin and inhibitors of death receptors signaling, adhesion and cytoskeleton dynamics, invasion and angiogenesis. For 10 proteins over-expression was confirmed by IHC thus demonstrating their druggability. Moreover, c-Myc over-expression caused complete gene silencing of 12 candidate genes, including Bmp6, Fbln1 and Ptprb to influence lung morphogenesis, invasiveness and cell signaling events. Conversely, among the 75 repressed genes TNFα and TGF-β pathways as well as negative regulators of IGF1 and MAPK signaling were affected. Additionally, anti-angiogenic, anti-invasive, adhesion and extracellular matrix remodeling and growth suppressive functions were repressed. For 15 candidate genes c-Myc-dependent DNA binding and transcriptional responses in human lung cancer samples were confirmed. Finally, Kaplan-Meier survival statistics revealed clinical significance for 59 out of 100 candidate genes, thus confirming their prognostic value. In conclusion, previously unknown c-Myc target genes in lung cancer were identified to enable the development of mechanism-based therapies.

Hoxa5 increases mitochondrial apoptosis by inhibiting Akt/mTORC1/S6K1 pathway in mice white adipocytes

Homeobox A5(Hoxa5), a member of the Hox family, plays a important role in the regulation of proliferation and apoptosis in cancer cells. The dysregulation of the adipocyte apoptosis in vivo leads to obesity and metabolic disorders. However, the effects of Hoxa5 on adipocyte apoptosis are still unknown. In this study, palmitic acid (PA) significantly increased the mRNA level of Hoxa5 and triggered white adipocyte apoptosis in vivo and in vitro. Further analysis revealed that Hoxa5 enhanced the early and late apoptotic cells and fragmentation of genomic DNA in adipocytes from inguinal white adipose tissue (iWAT) of mice. Moreover, Hoxa5 aggravated white adipocyte apoptosis through mitochondrial pathway rather than endoplasmic reticulum stress (ERS)-induced or death receptor (DR)-mediated pathway. Our data also confirmed that Hoxa5 promoted mitochondrial apoptosis pathway by elevating the transcription activity of Bax and inhibiting the protein kinase B (Akt)/mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. In summary, these findings revealed a novel mechanism that linked Hoxa5 to white adipocyte apoptosis, which provided some potential possibilities to prevent and treat obesity and some metabolic diseases.

Silencing of homeobox A5 gene in the stratum corneum of psoriasis

Analysis of psoriatic parakeratotic cells is helpful for understanding the pathogenesis of psoriasis. Methylation analysis can be performed on psoriatic scales, but it is unclear whether genes can be silenced by DNA methylation in psoriatic stratum corneum. The present study was conducted to detect genes silenced in psoriatic stratum corneum. Methylation array analysis with 485 577 probes, quantitative real-time methylation-specific PCR (RT-MSP) and bisulphite sequencing were performed for 30 psoriatic scale samples, 6 fully developed psoriatic skin samples and 12 normal skin samples. Immunohistochemical staining of HOXA5 was performed for 29 psoriatic epidermal samples and 13 normal epidermal samples. The genome-wide methylation array detected two CpG sites within CpG islands (CGIs) located in promoter regions of HOXA5 and LIAS that had methylation levels of >0.6 in at least one of the three psoriatic scale samples and of <0.2 in all three normal skin tissue samples (methylation rate range, 0.0-1.0). RT-MSP for HOXA5CGI, in which the primers were successfully developed, revealed that the average methylation level of 27 psoriasis scales (60.2%) is significantly higher than that of 9 normal skin samples (34.6%) (P=.013). Immunohistochemical staining revealed that HOXA5 protein was not expressed in the stratum corneum of fully developed psoriatic epidermis, but the protein was expressed in the stratum corneum of incompletely developed epidermis and normal epidermis. In conclusion, HOXA5 can be silenced in the stratum corneum of psoriasis. The silenced gene was identified by non-invasive methylation analysis of psoriatic scales.

Correlation Between Meis1 and Msi1 in Esophageal Squamous Cell Carcinoma

PURPOSE

Homeobox (HOX) transcription factors are critical regulators of cell fate, stem cell functions, and gastrointestinal development. They require three-amino acid loop extension (TALE) homeodomain proteins such as Meis1 to enhance their transcriptional efficiencies. There are complicated associations between different signaling pathways such as the Wnt and NOTCH and tumor progression. It has been investigated that GSK-3 as an important component of the Wnt pathway facilitates the expression of HOX target genes. Therefore, in the present study, we assessed the probable correlation between Wnt, NOTCH, and HOX genes in esophageal squamous cell carcinoma (ESCC) progression and metastasis through the correlational study between the Msi1 as an important activator for both of the NOTCH and Wnt pathways and Meis1.

METHODS

Levels of Meis1 and Msi1 messenger RNA (mRNA) expression in 51 ESCC patients were compared to the normal tissues using real-time polymerase chain reaction.

RESULTS

Only 3 out of 51 (5.9 %) cases had Meis1/Msi1 overexpression and also 3/51 (5.9 %) cases had Meis1/Msi1 underexpression. There was a significant correlation between the Msi1 and Mesi1 mRNA expression (p = 0.037). All of the Msi1/Meis1 underexpressed tumors were poorly differentiated (p = 0.003). Meis1 under/Msi1 overexpressed cases also were in T3 tumor depth of invasion (p = 0.019). And there was a significant correlation between the Msi1/Meis1 underexpression and gender (p = 0.045).

CONCLUSIONS

Our results show that Meis1 may have a positive feedback with Msi1 during the ESCC progression.

Identification of upstream transcription factors (TFs) for expression signature genes in breast cancer

Breast cancer is a common malignancy among women with a rising incidence. Our intention was to detect transcription factors (TFs) for deeper understanding of the underlying mechanisms of breast cancer. Integrated analysis of gene expression datasets of breast cancer was performed. Then, functional annotation of differentially expressed genes (DEGs) was conducted, including Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Furthermore, TFs were identified and a global transcriptional regulatory network was constructed. Seven publically available GEO datasets were obtained, and a set of 1196 DEGs were identified (460 up-regulated and 736 down-regulated). Functional annotation results showed that cell cycle was the most significantly enriched pathway, which was consistent with the fact that cell cycle is closely related to various tumors. Fifty-three differentially expressed TFs were identified, and the regulatory networks consisted of 817 TF-target interactions between 46 TFs and 602 DEGs in the context of breast cancer. Top 10 TFs covering the most downstream DEGs were SOX10, NFATC2, ZNF354C, ARID3A, BRCA1, FOXO3, GATA3, ZEB1, HOXA5 and EGR1. The transcriptional regulatory networks could enable a better understanding of regulatory mechanisms of breast cancer pathology and provide an opportunity for the development of potential therapy.

miR-429 mediates tumor growth and metastasis in colorectal cancer

Colorectal cancer (CRC), presenting the third most common malignancy worldwide. In recent years, the aberrantly upregulation or downregulation of miRNAs in CRC have been evidenced in a number of studies. In this study, our results showed that the expression of miR-429 was significantly higher in CRC tissue compared with adjacent non-tumor tissue. In addition, our findings showed that miR-429 level was significantly associated with clinicoplathological features and prognosis of patients with CRC. Moreover, our findings showed that miR-429 exerted oncogenic effect by directly targeting HOXA5, a transcription factor of HOX families that is involved in the development and progression of CRC.

A novel double-negative feedback loop between miR-489 and the HER2-SHP2-MAPK signaling axis regulates breast cancer cell proliferation and tumor growth

Human epidermal growth factor receptor 2 (HER2 or ErBb2) is a receptor tyrosine kinase overexpressed in 20-30% of breast cancers and associated with poor prognosis and outcome. Dysregulation of several microRNAs (miRNAs) plays a key role in breast cancer progression and metastasis. In this study, we screened and identified miRNAs dysregualted in HER2-positive breast cancer cells. Our molecular study demonstrated that miR-489 was specifically downregulated by the HER2-downstream signaling, especially through the MAPK pathway. Restoration or overexpression of miR-489 in HER2-positive breast cancer cells significantly inhibited cell growth in vitro and decreased the tumorigenecity and tumor growth in xenograft mice. Mechanistically, we found that overexpression of miR-489 led to the decreased levels of HER2 and SHP2 and thus attenuated HER2-downstream signaling. Furthermore, we for the first time demonstrated that HER2 is a direct target of miR-489 and therefore HER2-SHP2-MAPK and miR-489 signaling pathways form a mutually inhibitory loop. Using quantitative real-time PCR analysis and Fluorescent in situ hybridization technique (FISH), we found that miR-489 was expressed at significantly lower level in tumor tissues compared to the adjacent normal tissues. Downregulation of miR-489 in breast cancers was associated with aggressive tumor phenotypes. Overall, our results define a double-negative feedback loop involving miR-489 and the HER2-SHP2-MAPK signaling axis that can regulate breast cancer cell proliferation and tumor progression and might have therapeutic relevance for HER2-positive breast cancer.

A 10-Gene Yin Yang Expression Ratio Signature for Stage IA and IB Non-Small Cell Lung Cancer

INTRODUCTION

Lung cancer is the leading killer cancer worldwide. There is an urgent need for easy-to-use and robust clinical gene signatures for improved prognosis and treatment prediction.

METHODS

We used a gene expression signature termed the Yin and Yang mean ratio (YMR), which is based on two groups of genes with opposing function, to determine lung cancer prognosis. The YMR signature represents the relative state of an individual tumor on a gene expression spectrum ranging from malignancy to the normal healthy lung. The genes in the YMR signature have therefore been determined independently of survival time, which is different from previous regression models. We then leveraged the cross-platform utility of the YMR signature to optimize the signature into a smaller set of genes that validated the robustness of the signature in many independent lung cancer expression data sets.

RESULTS

Four Yin and six Yang genes were optimized using 741 NSCLC cases from diverse platforms, including microarray and RNA sequencing. The 10-gene signature demonstrated significant differences in survival in eight individual independent data sets and a larger combined 1346-patient data set. When multivariate analysis taking into account other common predictors of survival was used, the 5-year recurrence-free rate of YMR (p = 6.4 × 10^-6, HR =1.71 [1.36-2.16]) was secondary only to stage. The YMR signature significantly separated high- and low-risk patients with stage IA or 1B adenocarcinoma and squamous cell carcinomas of all stages. The YMR signature can also predict the benefit of adjuvant chemotherapy in high-risk patients with stage I NSCLC.

CONCLUSIONS

The YMR signature has great potential for guiding clinical management for NSCLC, particularly early-stage disease. The signature appears more reproducible than older signatures and functions using a variety of common gene expression platforms.

Circadian disruption and breast cancer: an epigenetic link?

Breast cancer is already the most common malignancy affecting women worldwide, and evidence is mounting that breast cancer induced by circadian disruption (CD) is a warranted concern. Numerous studies have investigated various aspects of the circadian clock in relation to breast cancer, and evidence from these studies indicates that melatonin and the core clock genes can play a crucial role in breast cancer development. Even though epigenetics has been increasingly recognized as a key player in the etiology of breast cancer and linked to circadian rhythms, and there is evidence of overlap between epigenetic deregulation and breast cancer induced by circadian disruption, only a handful of studies have directly investigated the role of epigenetics in CD-induced breast cancer. This review explores the circadian clock and breast cancer, and the growing role of epigenetics in breast cancer development and circadian rhythms. We also summarize the current knowledge and next steps for the investigation of the epigenetic link in CD-induced breast cancer.

HOXA5 determines cell fate transition and impedes tumor initiation and progression in breast cancer through regulation of E-cadherin and CD24

Loss of HOXA5 expression occurs frequently in breast cancer and correlates with higher pathological grade and poorer disease outcome. However, how HOX proteins drive differentiation in mammalian cells is poorly understood. In this paper, we investigated cellular and molecular consequences of loss of HOXA5 in breast cancer, and the role played by retinoic acid in HOXA5 function. Analysis of global gene expression data from HOXA5-depleted MCF10A breast epithelial cells, followed by validation, pointed to a role for HOXA5 in maintaining several molecular traits typical of the epithelial lineage such as cell-cell adhesion, tight junctions and markers of differentiation. Depleting HOXA5 in immortalized MCF10A or transformed MCF10A-Kras cells reduced their CD24⁺/CD44^lo population, enhanced self-renewal capacity and reduced expression of E-cadherin (CDH1) and CD24. In the case of MCF10A-Kras, HOXA5 loss increased branching and protrusive morphology in Matrigel, all features suggestive of epithelial to basal transition. Further, orthotopically implanted xenografts of MCF10A-Kras-scr grew as well-differentiated pseudo-luminal carcinomas, while MCF10A-Kras-shHOXA5 cells formed aggressive, poorly differentiated carcinomas. Conversely, ectopic expression of HOXA5 in aggressive SUM149 or SUM159 breast cancer cells reversed the cellular and molecular alterations observed in the HOXA5-depleted cells. Retinoic acid is a known upstream regulator of HOXA5 expression. HOXA5 depletion in MCF10A cells engineered to express doxycycline-induced shHOXA5 slowed transition of cells from a less differentiated CD24^-/CD44⁺ to the more differentiated CD24⁺/CD44⁺ state. This transition was promoted by retinal treatment, which upregulated endogenous HOXA5 expression and caused re-expression of occludin and claudin-7 (CLDN7). Expression of CDH1 and CD24 was transcriptionally upregulated by direct binding of HOXA5 to their promoter sequences as demonstrated by luciferase and ChIP analyses. Thus, loss of HOXA5 in mammary cells leads to loss of epithelial traits, an increase in stemness and cell plasticity, and the acquisition of more aggressive phenotypes.

Hoxa5: A Key Player in Development and Disease

A critical position in the developmental hierarchy is occupied by the Hox genes, which encode transcription factors. Hox genes are crucial in specifying regional identity along the embryonic axes and in regulating morphogenesis. In mouse, targeted mutations of Hox genes cause skeletal transformations and organ defects that can impair viability. Here, we present the current knowledge about the Hoxa5 gene, a paradigm for the function and the regulation of Hox genes. The phenotypic survey of Hoxa5-/- mice has unveiled its critical role in the regional specification of the skeleton and in organogenesis. Most Hoxa5-/- mice die at birth from respiratory distress due to tracheal and lung dysmorphogenesis and impaired diaphragm innervation. The severity of the phenotype establishes that Hoxa5 plays a predominant role in lung organogenesis versus other Hox genes. Hoxa5 also governs digestive tract morphogenesis, thyroid and mammary glands development, and ovary homeostasis. Deregulated Hoxa5 expression is reported in cancers, indicating Hoxa5 involvement in tumor predisposition and progression. The dynamic Hoxa5 expression profile is under the transcriptional control of multiple cis-acting sequences and trans-acting regulators. It is also modulated by epigenetic mechanisms, implicating chromatin modifications and microRNAs. Finally, lncRNAs originating from alternative splicing and distal promoters encompass the Hoxa5 locus.

Cellular and molecular insights into Hox protein action

Hox genes encode homeodomain transcription factors that control morphogenesis and have established functions in development and evolution. Hox proteins have remained enigmatic with regard to the molecular mechanisms that endow them with specific and diverse functions, and to the cellular functions that they control. Here, we review recent examples of Hox-controlled cellular functions that highlight their versatile and highly context-dependent activity. This provides the setting to discuss how Hox proteins control morphogenesis and organogenesis. We then summarise the molecular modalities underlying Hox protein function, in particular in light of current models of transcription factor function. Finally, we discuss how functional divergence between Hox proteins might be achieved to give rise to the many facets of their action.

Effect of silencing HOXA5 gene expression using RNA interference on cell cycle and apoptosis in Jurkat cells

Acute lymphocytic leukemia (ALL) is a common malignant tumor with a high morbidity rate among children, accounting for approximately 80% of leukemia cases. Although there have been improvements in the treatment of patients frequent relapse lead to a poor prognosis. The aim of the present study was to determine whether HOXA5 may be used as a target for gene therapy in leukemia in order to provide a new treatment. Mononuclear cells were extracted from the bone marrow according to the clinical research aims. After testing for ALL in the acute stage, the relative mRNA and protein expression of HOXA5 was detected in the ALL remission groups (n=25 cases per group) and the control group [n=20 cases, immune thrombocytopenia (ITP)]. Gene silencing by RNA interference (RNAi) was used to investigate the effect of silencing HOXA5 after small interfering RNA (siRNA) transfection to Jurkat cells. The HOXA5-specific siRNA was transfected to Jurkat cells using lipofectamine. The experiment was divided into the experimental group (liposomal transfection of HOXA5 targeting siRNA), the negative control group (liposomal transfection of cells with negative control siRNA) and the control group (plus an equal amount of cells and culture media only). Western blotting and quantitative fluorescent polymerase chain reaction (QF‑PCR) were used to detect the relative HOXA5 mRNA expression and protein distribution in each cell group. Cell distribution in the cell cycle and the rate of cells undergoing apoptosis were determined using flow cytometry. The expression of HOXA5 at the mRNA and protein levels in the acute phase of ALL was significantly higher than that in ALL in the remission and control groups. In cells transfected with HOXA5-specific siRNA, the expression of HOXA5 at the mRNA and protein levels decreased significantly (P<0.05). The distribution of cells in the cell cycle was also altered. Specifically, more cells were present in the G0/G1 phase compared to the S phase (P<0.05). In addition, the apoptotic rate was significantly higher in cells transfected with HOXA5‑specific siRNA (P<0.05). In conclusion, high expression levels of HOXA5 mRNA and protein in children with ALL indicate that HOXA5 is closely associated with childhood ALL. In addition, HOXA5-specific siRNA effectively silences HOXA5 gene expression and induces apoptosis and cell-cycle arrest in Jurkat cells, thus inhibiting cell proliferation.