Midline morphogenesis of zebrafish foregut endoderm is dependent on Hoxb5b.

During vertebrate embryonic development complex morphogenetic events drive the formation of internal organs associated with the developing digestive tract. The foregut organs derive from hepatopancreatic precursor cells that originate bilaterally within the endoderm monolayer, and subsequently converge toward the midline where they coalesce to produce the gut tube from which the liver and pancreas form. The progenitor cells of these internal organs are influenced by the lateral plate mesoderm (LPM), which helps direct them towards their specific fates. However, it is not completely understood how the bilateral organ precursors move toward the embryonic midline and ultimately coalesce to form functional organs. Here we demonstrate that the zebrafish homeobox gene hoxb5b regulates morphogenesis of the foregut endoderm at the midline. At early segmentation stages, hoxb5b is expressed in the LPM adjacent to the developing foregut endoderm. By 24 hpf hoxb5b is expressed directly in the endoderm cells of the developing gut tube. When Hoxb5b function is disrupted, either by morpholino knockdown or sgRNA/Cas9 somatic disruption, the process of foregut morphogenesis is disrupted, resulting in a bifurcated foregut. By contrast, knockdown of the paralogous hoxb5a gene does not alter gut morphology. Further analysis has indicated that Hoxb5b knockdown specimens produce endocrine pancreas cell types, but liver cells are absent. Finally, cell transplantation experiments revealed that Hoxb5b function in the endoderm is not needed for proper coalescence of the foregut at the midline. Together, our findings imply that midline morphogenesis of foregut endoderm is guided by a hoxb5b-mediated mechanism that functions extrinsically, likely within the LPM. Loss of hoxb5b function prevents normal coalescence of endoderm cells at the midline and thus disrupts gut morphogenesis.

Identification of the minimum requirements for successful haematopoietic stem cell transplantation.

Historically, defining haematopoietic subsets, including self-renewal, differentiation and lineage restriction, has been elucidated by transplanting a small number of candidate cells with many supporting bone marrow (BM) cells. While this approach has been invaluable in characterising numerous distinct subsets in haematopoiesis, this approach is arguably flawed. The haematopoietic stem cell (HSC) has been proposed as the critical haematopoietic subset necessary for transplantation. However, due to the presence of supporting cells, the HSC has never demonstrated sufficiency. Utilising the homeobox B5 (Hoxb5)-reporter system, we found that neither long-term (LT) HSCs nor short-term (ST) HSCs alone were sufficient for long-term haematopoietic reconstitution. Critically, reconstitution can be rescued by transplanting combined LT- and ST-HSCs, without supporting cells; a fraction we term the 'Minimum Subset for Transplantation' (MST). The MST accounts for only 0·005% of nucleated cells within mouse BM, and this MST can be cultured, expanded and genetically modified while preserving its rapid haematopoietic engraftment potential. These results support the consideration of an MST approach for clinical translation, especially for gene therapy approaches that require HSC compartment modification.

Hoxb5 defines the heterogeneity of self-renewal capacity in the hematopoietic stem cell compartment.

Self-renewal and multipotency are essential functions of hematopoietic stem cells (HSCs). To maintain homeostatic hematopoiesis, functionally uniform HSCs have been thought to be an ideal cell-of-origin. Recent technological advances in the field have allowed us to analyze HSCs with single cell resolution and implicate that functional heterogeneity may exist even within the highly purified HSC compartment. However, due in part to the technical limitations of analyzing extremely rare populations and our incomplete understanding of HSC biology, neither the biological meaning of why heterogeneity exists nor the precise mechanism of how heterogeneity is determined within the HSC compartment is entirely known. Here we show the first evidence that self-renewal capacity varies with the degree of replication stress dose and results in heterogeneity within the HSC compartment. Using the Hoxb5-reporter mouse line which enables us to distinguish between long-term (LT)-HSCs and short-term (ST)-HSCs, we have found that ST-HSCs quickly lose self-renewal capacity under high stress environments but can maintain self-renewal under low stress environments for long periods of time. Critically, exogeneous Hoxb5 expression confers protection against loss of self-renewal to Hoxb5-negative HSCs and can partially alter the cell fate of ST-HSCs to that of LT-HSCs. Our results demonstrate that Hoxb5 imparts functional heterogeneity in the HSC compartment by regulating self-renewal capacity. Additionally, Hoxb5-positive HSCs may exist as fail-safe system to protect from the exhaustion of HSCs throughout an organism's lifespan.

Homeobox B5 suppression attenuates proliferation and elevates apoptosis in hepatoma cell lines through ERK/MDM2 signalling.

Homeobox B5 (HOXB5), a member of the HOX gene family, is an important gene in tumourigenesis. However, its role in hepatocellular carcinoma (HCC) cell proliferation and apoptosis remains unclear. In this study, we investigated the role and regulation mechanism of HOXB5 in HCC cell lines Hep3B and LM6. The data indicated high expression of HOXB5 in HCC tissues and cell lines. In HCC cells, inhibition of HOXB5 by transfection with HOXB5 siRNA significantly constrained cell viability, and Bcl-2 levels, and it increased cell apoptosis, cytochrome c levels, BAX levels, and caspase-3 activity. On the contrary, HOXB5 overexpression increased proliferation and Bcl-2 levels but inhibited BAX levels and caspase-3 activity in these cells. HOXB5 downregulation attenuated activation of extracellular signal-regulated kinase (ERK) and expression of the murine double minute 2 (MDM2) oncogene. Incubation with the ERK activator, phorbol 12-myristate 13-acetate (40 µmol/L), for 12 hours reversed the effects of HOXB5 inhibition on MDM2 expression, cell proliferation, and apoptosis in HCC cells. Overall, this study demonstrated that HOXB5 inhibition regulated MDM2 expression by controlling ERK activation and that it modulated proliferation and apoptosis in HCC cells.

[Significance and purification of long-term hematopoietic stem cells in the hematopoietic system].

The hematopoietic stem cells, defined as blood stem cells with self-replication ability and multipotency, are key to successful hematopoietic stem cell transplantation. With the history of transplantation in the past 60 years and advances in stem cell technologies, our understanding of the hematopoietic system has deepened. However, the molecular mechanisms of self-renewal and pluripotency, which are the essence of the hematopoietic stem cells, remain poorly understood. One reason is that the identification/purification methods of the hematopoietic stem cells, particularly the long-term hematopoietic stem cells capable of lifelong self-renewal, is technically difficult owing to their scarcity in the bone marrow and has not been established to this date. Considering that a long-lasting blood production after hematopoietic stem cell transplantation is crucial, it is essential to understand the biology of the long-term hematopoietic stem cells not only scientifically but also clinically. This review describes the scientific and clinical significance of the long-term hematopoietic stem cells by showing the results of the latest researches in the introduction of hematopoietic stem cell identification/purification history.

Transcriptional activation of EGFR by HOXB5 and its role in breast cancer cell invasion.

HOX genes are transcription factors that play important roles in body patterning and many cellular processes during embryonic, fetal, and adult development. Given their important function in normal tissues, it is reasonable to assume that abnormal expression of HOX genes in adults could lead to serious diseases such as cancer. Our previous study reported HOXB5 to be significantly up-regulated in breast cancer, and its expression was found to be associated with tumor cell proliferation and invasion. Furthermore, the epidermal growth factor receptor (EGFR), a cellular tyrosine kinase that plays an important role in breast cancer progression, was found significantly up-regulated by HOXB5 in ER-positive breast cancer cells. In the present study, we demonstrated that HOXB5 regulates EGFR expression at the transcriptional level by directly binding to its promoter region and promotes phosphorylation of EGFR as well as its downstream effectors. Patients with ER-positive breast cancer, having high co-expression of HOXB5 and EGFR, had poor prognosis than those with low expression. Knockdown studies validated a key role played by EGFR in the HOXB5-induced invasion of breast cancer cells. These results suggest that targeting EGFR could be an effective strategy to treat breast cancer in patients with high HOXB5 expression.

miR-455-3p serves as prognostic factor and regulates the proliferation and migration of non-small cell lung cancer through targeting HOXB5.

MicroRNAs (miRs) have been reported to play significantly roles in the initiation and progression of human cancers. miR-455-3p has been recently found could function as tumor suppressor in various human cancers. However, its expression and biological role in non-small cell lung cancer (NSCLC) remains elusive. In this study, we found miR-455-3p was markedly downregulated in NSCLC tissues and cell lines. Chi-square test to analyze the correlations between miR-455-3p expression and clinicopathological features revealed that miR-455-3p expression was correlated with poorly differentiated cancer and advanced tumor stage (P < 0.05). Kaplan-Meier curve revealed that low expression of miR-455-3p was correlated with shorter 5-year survival time (P = 0.029). Univariate and multivariate analyses identified low miR-455-3p expression was an unfavorable prognostic factor for overall survival. Gain-of-function and loss-of-function studies revealed that miR-455-3p inhibits cell proliferation and migration in vitro. Computer algorithm and dual-luciferase reporter assay revealed that miR-455-3p directly targets and suppresses HOXB5 in NSCLC. Further studies demonstrated that knockdown of HOXB5 attenuated the effect of miR-455-3p downregulation on cell proliferation and migration. Taken together, our results for the first time suggested that miR-455-3p was downregulated in NSCLC and was correlated with the poor prognosis of NSCLC patients. Also, miR-455-3p functions as tumor suppressor by directly targeting HOXB5 in NSCLC progression and may be used as a potential target for NSCLC treatment.

Heterogeneous pattern of DNA methylation in developmentally important genes correlates with its chromatin conformation.

BACKGROUND: DNA methylation is a major epigenetic modification, playing a crucial role in the development and differentiation of higher organisms. DNA methylation is also known to regulate transcription by gene repression. Various developmental genes such as c-mos, HoxB5, Sox11, and Sry show tissue-specific gene expression that was shown to be regulated by promoter DNA methylation. The aim of the present study is to investigate the establishment of chromatin marks (active or repressive) in relation to heterogeneous methylation in the promoter regions of these developmentally important genes. RESULTS: Chromatin-immunoprecipitation (ChIP) assays were performed to immuno-precipitate chromatin by antibodies against both active (H3K4me3) and repressive (H3K9me3) chromatin regions. The analysis of ChIP results showed that both the percentage input and fold enrichment of activated chromatin was higher in tissues expressing the respective genes as compared to the tissues not expressing the same set of genes. This was true for all the genes selected for the study (c-mos, HoxB5, Sox11, and Sry). These findings illustrate that inconsistent DNA methylation patterns (sporadic, mosaic and heterogeneous) may also influence gene regulation, thereby resulting in the modulation of chromatin conformation. CONCLUSIONS: These findings illustrate that various patterns of DNA methylation (asynchronous, mosaic and heterogeneous) correlates with chromatin modification, resulting in the gene regulation.

HOXB5 induces invasion and migration through direct transcriptional up-regulation of ß-catenin in human gastric carcinoma.

HOX (homeobox) genes encode a family of transcriptional regulators, which have an important role in morphogenesis and differentiation during embryonic development. Their deregulated expression is involved in the carcinogenesis of many human solid tumours. In the present study, we show that HOXB5 mRNA was significantly overexpressed in gastric cancer tissues compared with adjacent normal tissues. HOXB5-up-regulated cancer cells showed increased invasion and migration activity, but no change in proliferation activity, whereas HOXB5-down-regulated cells showed decreased invasion and migration activity. Up-regulation of HOXB5 resulted in up-regulation of ß-catenin, whereas inhibition of HOXB5 expression by siRNA led to the down-regulation of ß-catenin. Moreover, a significant correlation between HOXB5 and CTNNB1 (ß-catenin) mRNA expression was detected in gastric cancer tissues. Furthermore, we found that HOXB5 binds directly to the CTNNB1 promoter region and activates the transcriptional expression of ß-catenin, as well as its downstream target genes, encoding cyclin D1 and c-Myc, leading to an increase in the invasion and migration activity of human gastric cancer cells. Thus HOXB5 may be an important regulator of the Wnt/ß-catenin signalling pathway, thereby contributing to gastric cancer progression and metastasis.

Roles of Hoxb5 in the development of vagal and trunk neural crest cells.

Neural crest cells (NC) are a group of multipotent stem cells uniquely present in vertebrates. They are destined to form various organs according to their anterior-posterior (A-P) levels of origin in the neural tube (NT). They develop into a wide spectrum of cell lineages under the influence of signaling cascades, neural plate border genes and NC specifier genes. Although this complex gene regulatory network (GRN) specifies the fate of NC and the combinatory action of Hox genes executed at the time of NC induction governs the patterning of NC for the formation of specific structures along the A-P axis, not much information on how GRN and Hox genes directly interact and orchestrate is available. This review summarizes recent findings on the multiple roles of Hoxb5 on the survival and cell lineage differentiation of vagal and trunk NC cells during early development, by direct transcriptional regulation of NC specifier genes (Sox9 and Foxd3) of the GRN. We will also review findings on the transcriptional regulation of Ret by Hoxb5 in the population of the vagal NC that are committed to the enteric neuron and glia lineages. Functional redundancy between Hox proteins (Hoxa5 and Hoxc5) from the same paralogue group as Hoxb5, and the cooperative effects of Hox cofactors, collaborators and transcription factors in the Hoxb5 transcriptional regulation of target genes will also be discussed.

HOXB5 promotes the progression and metastasis of osteosarcoma cells by activating the JAK2/STAT3 signalling pathway.

Objective: To investigate the involvement of the homeobox gene B5 (HOXB5) in the progression and metastasis of osteosarcoma. Methods: The expression of HOXB5 in human osteosarcoma tissues and its correlation with clinical indicators were investigated using bioinformatics analysis and immunohistochemical labelling. Human osteosarcoma cells (HOS, MG63, U2OS, and Saos-2) and normal human osteoblasts (hFOB1.19) were cultivated. The expression of HOXB5 in these cells was detected using western blotting (WB) and RT‒PCR. Two cell lines exhibiting elevated HOXB5 expression were chosen and divided into three groups: the blank group (mock), control group (control) and transfection group (shHOXB5). The transfection group was infected with lentivirus expressing shRNAs targeting HOXB5. The transfection efficiency was detected by WB. Cell proliferation suppression was measured by CCK-8 and 5-ethynyl-2'-deoxyuridine (EdU) assays; the percentage of apoptotic cells was determined by flow cytometry; and cell migration and invasion were detected via the Transwell chamber test. WB was utilized to determine the protein expression of genes linked to metastasis (MMP2, MMP9), apoptosis (Bax, Bcl-2), and the JAK2/STAT3 pathway (JAK2, p-JAK2, STAT3, p-STAT3). Results: In osteosarcoma tissues, HOXB5 expression was elevated and strongly correlated with distant metastasis. Silencing HOXB5 reduced the proliferation, migration and invasion of osteosarcoma cells; prevented the progression and metastasis of tumours in tumour-bearing nude mice; and reduced the activation of key proteins in the JAK2/STAT3 signalling pathway. Conclusion: Through the JAK2/STAT3 signalling pathway, HOXB5 plays a crucial role in the malignant progression of osteosarcoma and is a promising target for osteosarcoma treatment.

Transcription factor Hoxb5 reveals the unidirectional hierarchy of hematopoietic stem cell pool.

Hoxb5 exhibits preferential expression in hematopoietic stem cells (HSCs) and uniquely marks the long-term HSCs (LT-HSCs). Previous studies have demonstrated the remarkable capability of Hoxb5 to alter cell fates when enforced expression in blood progenitors, such as B cell progenitors and multipotent progenitors. Additionally, Hoxb5 deficiency does not hinder the generation of LT-HSCs. However, the specific impact of Hoxb5 deletion on LT-HSCs has remained unexplored. To address this, we developed a conditional Hoxb5 knockout-reporter mouse model, wherein Hoxb5 was knock out by the Vav-cre recombinase, and the endogenous Hoxb5 promoter drove the expression of the blue fluorescent protein (BFP). Our findings revealed that the primary recipients, who transplanted with HSCs indicating Hoxb5 deficiency by the presence of BFP (BFP-positive HSCs), exhibited comparable levels of donor chimerism and lineage chimerism to recipients transplanted with HSCs that spontaneously did not express Hoxb5 and thus lacked BFP expression (BFP-negative HSCs). However, during the secondary transplantation, recipients receiving total bone marrow (BM) from the primary recipients with BFP-positive HSCs showed significantly higher levels of donor chimerism and more robust multi-lineage chimerism compared to those receiving total BM from the primary recipients with BFP-negative HSCs. Our results indicate that deleting Hoxb5 in LT-HSCs transiently influences their lineage differentiation bias without compromising their long-term self-renewal capacity. These findings highlight the primary role of Hoxb5 in regulating lineage commitment decisions in LT-HSCs, while emphasizing that its presence is not indispensable for the maintenance of long-term self-renewal capacity.

A time- and single-cell-resolved model of murine bone marrow hematopoiesis.

The paradigmatic hematopoietic tree model is increasingly recognized to be limited, as it is based on heterogeneous populations largely defined by non-homeostatic assays testing cell fate potentials. Here, we combine persistent labeling with time-series single-cell RNA sequencing to build a real-time, quantitative model of in vivo tissue dynamics for murine bone marrow hematopoiesis. We couple cascading single-cell expression patterns with dynamic changes in differentiation and growth speeds. The resulting explicit linkage between molecular states and cellular behavior reveals widely varying self-renewal and differentiation properties across distinct lineages. Transplanted stem cells show strong acceleration of differentiation at specific stages of erythroid and neutrophil production, illustrating how the model can quantify the impact of perturbations. Our reconstruction of dynamic behavior from snapshot measurements is akin to how a kinetoscope allows sequential images to merge into a movie. We posit that this approach is generally applicable to understanding tissue-scale dynamics at high resolution.

Partial functional redundancy between Hoxa5 and Hoxb5 paralog genes during lung morphogenesis.

Hox genes encode transcription factors governing complex developmental processes in several organs. A subset of Hox genes are expressed in the developing lung. Except for Hoxa5, the lack of overt lung phenotype in single mutants suggests that Hox genes may not play a predominant role in lung ontogeny or that functional redundancy may mask anomalies. In the Hox5 paralog group, both Hoxa5 and Hoxb5 genes are expressed in the lung mesenchyme whereas Hoxa5 is also expressed in the tracheal mesenchyme. Herein, we generated Hoxa5;Hoxb5 compound mutant mice to evaluate the relative contribution of each gene to lung development. Hoxa5;Hoxb5 mutants carrying the four mutated alleles displayed an aggravated lung phenotype, resulting in the death of the mutant pups at birth. Characterization of the phenotype highlighted the role of Hoxb5 in lung formation, the latter being involved in branching morphogenesis, goblet cell specification, and postnatal air space structure, revealing partial functional redundancy with Hoxa5. However, the Hoxb5 lung phenotypes were less severe than those seen in Hoxa5 mutants, likely because of Hoxa5 compensation. New specific roles for Hoxa5 were also unveiled, demonstrating the extensive contribution of Hoxa5 to the developing respiratory system. The exclusive expression of Hoxa5 in the trachea and the phrenic motor column likely underlies the Hoxa5-specific trachea and diaphragm phenotypes. Altogether, our observations establish that the Hoxa5 and Hoxb5 paralog genes shared some functions during lung morphogenesis, Hoxa5 playing a predominant role.

Increased Expression of Homeobox 5 Predicts Poor Prognosis: A Potential Prognostic Biomarker for Glioma.

Background: The homeobox gene 5 (HOXB5) encodes a transcription factor that regulates the embryonic development of the central nervous system. Notably, its expression pattern and prognostic role in glioma remain unelucidated. Methods: This study identified the relationship between HOXB5 and glioma by investigating HOXB5 expression data from The Cancer Genome Atlas and the Genotype Tissue Expression databases and validating the obtained data using the Chinese Glioma Genome Atlas database. Western blots were used to identify HOXB5 expression levels in glioma cells and clinical samples. Kaplan-Meier and multivariate Cox regression analyses were performed to assess the prognostic value of HOXB5. The key functions and signaling pathways related to HOXB5 were analyzed using GO, KEGG, and GSEA. Immune infiltration was calculated using the microenvironment cell populations-counter, estimate the proportion of immune and cancer, and ESTIMATE algorithms. Results: The expression of HOXB5 was upregulated in glioma and generally increased with malignancy. HOXB5 was an independent prognostic factor for glioma patients. A nomogram was further built that integrated HOXB5, and it showed stratifying prediction accuracy and efficiency. HOXB5 was associated with the regulation of cell growth, endothelial cell growth, and the IL-6/JAK-STAT3 pathway, and was determined to possibly promote stomatal specimen enrichment and angiogenesis. Conclusion: HOXB5 protein is overexpressed in glioma and might serve as a good predictive factor of this disease.

CARD9 contributes to ovarian cancer cell proliferation, cycle arrest, and cisplatin sensitivity.

BACKGROUND: Ovarian cancer recurrence and chemotherapy resistance are still urgent issues, and exploring the mechanisms of metastasis and chemotherapy resistance is beneficial to the development of therapeutic methods. Caspase recruitment domain family member 9 (CARD9) and homeobox B5 (HOXB5) are related and both are upregulated in ovarian cancer. This study aimed to define their functions in ovarian cancer cell proliferation, migration, and cisplatin sensitivity. RESULTS: The levels of CARD9 were detected in acquired ovarian cancer tissues and cell lines. CARD9 was indeed abnormally upregulated in them. CARD9 knockdown significantly suppressed cell proliferation, colony formation, migration, cycle arrest, and cisplatin sensitivity. HOXB5 bound to the CARD9 promoter, and HOXB5 overexpression reversed the regulation by CARD9 knockdown in cells, as well as the activation of NF-κB signaling. This indicated that CARD9 was positively regulated by HOXB5 in ovarian cancer cells. CONCLUSION: Together, CARD9 is involved in ovarian cancer cell proliferation, migration, and cisplatin sensitivity via NF-κB signaling after transcriptional activation by HOXB5.

miR-200a-3p- and miR-181-5p-Mediated HOXB5 Upregulation Promotes HCC Progression by Transcriptional Activation of EGFR.

Background: Hepatocellular carcinoma (HCC) remains a worldwide burden. However, the mechanisms behind the malignant biological behavior of HCC remain unclear. The homeobox (HOX) family could act as either promoters or suppressors in different kinds of malignancies. Our study discovered the role of HOXB5 in regulating HCC progression. Methods: The HOXB5 expression was assessed by RT-PCR analysis in human HCC samples and cell lines. HOXB5 transcriptional regulation of the EGFR was verified by the luciferase reporter assay and chromatin immunoprecipitation experiment. The oncogenic role of HOXB5 in HCC progression was analyzed by CCK8, colony-forming, and transwell assays. Results: Upregulation of HOXB5 was found in human HCC, and was strongly correlated with HCC tumor size, tumor-nodule metastasis, TNM stage, and relatively unfavorable OS and DFS. Ectopic expression of HOXB5 promoted the capacity of cell growth and clonogenicity, while the inhibition of HOXB5 decreased the proliferation and clonogenicity potential in vitro by CCK8 and colony-forming assays. In addition, HOXB5 also promoted cell migration by transwell experiment. Mechanism studies elucidated that HOXB5 triggers HCC progression via direct transcriptional activation of EGFR. The upregulation of HOXB5 is regulated by miR-200a-3p and miR-181-5p. Transfection of miR-200a-3p and miR-181-5p mimics blocked the cell proliferation and migration regulated by HOXB5, while overexpression of the 3'-UTR mutant HOXB5 abolished the suppressive effect of miR-200a-3p and miR-181-5p, but not the wild-type HOXB5. Conclusion: HOXB5 is a promising prognostic factor in human HCC. Targeting miR-200a-3p and the miR-181-5p/HOXB5/EGFR signaling pathway may provide new options for the treatment strategies of HCC.

Circ_0020123 enhances the cisplatin resistance in non-small cell lung cancer cells partly by sponging miR-140-3p to regulate homeobox B5 (HOXB5).

Cisplatin (DDP) therapy is widely used for the treatment of non-small cell lung cancer (NSCLC), but the curative effect is limited by chemoresistance. This study was designed to explore circ_0020123 function in DDP resistance of NSCLCDDP. Expression detection for circ_0020123, microRNA-140-3p (miR-140-3p) and homeobox B5 (HOXB5) was performed by real-time polymerase chain reaction (qRT-PCR). Half inhibitory concentration (IC50) of DDP and cell proliferation was detected by Cell Counting Kit-8 (CCK-8) assay. Colony formation ability was assessed using colony formation assay. Cell migration and invasion were evaluated via transwell assay. Cell apoptosis was examined by flow cytometry. Protein analysis was conducted by Western blot. Dual-luciferase reporter assay was used to affirm target interaction. Circ_0020123 expression was upregulated in DDP-resistant NSCLC cells. DDP resistance was reduced by downregulation of circ_0020123 in NSCLC cells. Circ_0020123 was identified as a miR-140-3p sponge. The effect of si-circ_0020123 on DDP resistance was partly associated with miR-140-3p upregulation. HOXB5 was a downstream target for miR-140-3p. Overexpression of HOXB5 mitigated miR-140-3p-induced inhibition of DDP resistance in NSCLC cells. Circ_0020123 upregulated the level of HOXB5 partly via sponging miR-140-3p. Also, circ_0020123 promoted tumor growth in NSCLC/DDP xenografts by regulating miR-140-3p and HOXB5 levels at least in part. These results revealed that circ_0020123 promoted DDP resistance in NSCLC cells partly by targeting miR-140-3p/HOXB5 axis, indicating that circ_0020123 might be used as a molecular target in DDP treatment for NSCLC.

HOXB5 promotes the progression of breast cancer through wnt/beta-catenin pathway.

OBJECTIVE: The present study was designed to explore the function of HOXB5 in breast cancer and related signaling pathway. METHODS: Breast cancer tissues and non-cancerous tissues were collected from 82 cases who were pathologically diagnosed with breast cancer. The mRNA level of HOXB5 was detected via quantitative real-time polymerase chain reaction (qRT-PCR). Chi-square test was adopted to analyze the association of HOXB5 with clinical features. The viability, migration and invasion of breast cancer cells were detected through MTT and Transwell assays, respectively. Protein analysis was performed adopting western blot analysis. RESULTS: HOXB5 expression was increased in breast cancer tissues and cells, and showed positive correlation with tumor size (P = 0.028), TNM stage (P = 0.048), and lymph node metastasis (P = 0.002). Losing HOXB5 expression suppressed clone formation, proliferation, migration and invasion of breast cancer cells. The knockdown of HOXB5 significantly inactivated wnt/ß-catenin pathway. Furthermore, wnt/ß-catenin pathway had the potential to neutralize the oncogenic function of HOXB5 in breast cancer. CONCLUSION: HOXB5 may be involved in the invasive progression of breast cancer. The function of HOXB5 in breast cancer was mediated by wnt/ß-catenin pathway.

HOXB5 Confers Tamoxifen Resistance in Breast Cancer Cells and Promotes Tumor Aggression and Progression.

BACKGROUND/AIM: ER-positive breast cancer patients commonly undergo endocrine therapy with drugs such as tamoxifen. Despite tamoxifen being a highly effective drug, long-term treatment results in resistance in one-third of the patients. Although many explanations for the development of tamoxifen resistance have been put forward, a clearly defined underlying mechanism is still lacking. MATERIALS AND METHODS: The expression level of HOXB5 was evaluated between MCF7 breast cancer cells and tamoxifen-resistant MCF7 (TAMR) cells by RT-PCR. Then, the effect of HOXB5 on invasion and migration abilities as well as on cancer stemness were investigated through 3D culture and spheroid formation assay. RESULTS: In this study, we provide evidence that HOXB5 is up-regulated in TAMR cells. EGFR is concurrently overexpressed, and the EGFR signaling cascade is activated, resulting in migratory and invasive phenotypes in TAMR cells compared to MCF7 cells. However, HOXB5 knockdown in TAMR cells resulted in the de-activation of the EGFR signaling pathway, less aggressive phenotypes and restoration of sensitivity to tamoxifen treatment. More interestingly, TAMR cells expressed higher levels of stem cell markers, and as a result, their enhanced stemness allowed for a better formation of spheroids than MCF7 cells. When HOXB5 was overexpressed in MCF7 cells, they were able to form a larger number of spheroids as in TAMR cells. CONCLUSION: HOXB5 is one of the key factors involved in tumor aggression and progression in tamoxifen-resistant breast cancer cells.