HOXB13 mediates tamoxifen resistance and invasiveness in human breast cancer by suppressing ERα and inducing IL-6 expression

Correlating Predicted Adjuvant Therapy Benefit and Risk of Recurrence Between Breast Cancer Index (BCI) and the 21-Gene Oncotype DX Recurrence Score (RS)

INTRODUCTION

Breast Cancer Index (BCI) is a genomic assay that evaluates the benefit of extending endocrine therapy (ET) from 5 to 10 years and predicts recurrence risk (RR). We evaluated the association between BCI and Oncotype DX (ODX).

PATIENTS

Women with hormone receptor (HR)-positive early-stage breast cancer (EBC) who had BCI and ODX performed were included.

METHODS

We performed a retrospective review of women with HR-positive EBC. BCI was categorized as predictive of extended ET versus not and ODX recurrence score (RS) as low (0-10), intermediate (11-25), and high (26-100). Univariate and multivariable logistic and linear regression models assessed the relationship between BCI and ODX, factors associated with each, and discordance between scores.

RESULTS

We identified 153 women, 22% were premenopausal and 18% were lymph node positive. The univariate logistic and linear models revealed an association between BCI predictive score and ODX RS (OR 7.84, CI, 2.63-23.36, P < .001) and log of BCI RR (Beta 0.04, CI, 0.02-0.06, P < .001). Seventy-four percent of BCI predictive scores were concordant with ODX RS and 83% of BCI RR was concordant with ODX RR. In a univariate logistic regression model, BCI predictive of ET benefit was associated with discordance (OR 28.00, CI, 10.58-74.02, P < .001). Higher ODX RR was associated with discordance (OR 1.92, CI, 1.42-2.59, P < .001).

CONCLUSION

We found a significant association between ODX and BCI predictive and prognostic scores. BCI predictive of extended ET benefit was associated with discordance with ODX RS. Higher predicted RR on ODX was associated with discordance with BCI predicted RR.

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.

Breast Cancer Index in Premenopausal Women With Early-Stage Hormone Receptor-Positive Breast Cancer

Importance

Adjuvant ovarian function suppression (OFS) with oral endocrine therapy improves outcomes for premenopausal patients with hormone receptor-positive (HR+) breast cancer but adds adverse effects. A genomic biomarker for selecting patients most likely to benefit from OFS-based treatment is lacking.

Objective

To assess the predictive and prognostic performance of the Breast Cancer Index (BCI) for OFS benefit in premenopausal women with HR+ breast cancer.

Design, Setting, and Participants

This prospective-retrospective translational study used all available tumor tissue samples from female patients from the Suppression of Ovarian Function Trial (SOFT). These individuals were randomized to receive 5 years of adjuvant tamoxifen alone, tamoxifen plus OFS, or exemestane plus OFS. BCI testing was performed blinded to clinical data and outcome. The a priori hypothesis was that BCI HOXB13/IL17BR ratio (BCI[H/I])-high tumors would benefit more from OFS and high BCI portended poorer prognosis in this population. Settings spanned multiple centers internationally. Participants included premenopausal female patients with HR+ early breast cancer with specimens in the International Breast Cancer Study Group tumor repository available for RNA extraction. Data were collected from December 2003 to April 2021 and were analyzed from May 2022 to October 2022.

Main Outcomes and Measures

Primary end points were breast cancer-free interval (BCFI) for the predictive analysis and distant recurrence-free interval (DRFI) for the prognostic analyses.

Results

Tumor specimens were available for 1718 of the 3047 female patients in the SOFT intention-to-treat population. The 1687 patients (98.2%) who had specimens that yielded sufficient RNA for BCI testing represented the parent trial population. The median (IQR) follow-up time was 12 (10.5-13.4) years, and 512 patients (30.3%) were younger than 40 years. Tumors were BCI(H/I)-low for 972 patients (57.6%) and BCI(H/I)-high for 715 patients (42.4%). Patients with tumors classified as BCI(H/I)-low exhibited a 12-year absolute benefit in BCFI of 11.6% from exemestane plus OFS (hazard ratio [HR], 0.48 [95% CI, 0.33-0.71]) and an absolute benefit of 7.3% from tamoxifen plus OFS (HR, 0.69 [95% CI, 0.48-0.97]) relative to tamoxifen alone. In contrast, patients with BCI(H/I)-high tumors did not benefit from either exemestane plus OFS (absolute benefit, -0.4%; HR, 1.03 [95% CI, 0.70-1.53]; P for interaction = .006) or tamoxifen plus OFS (absolute benefit, -1.2%; HR, 1.05 [95% CI, 0.72-1.54]; P for interaction = .11) compared with tamoxifen alone. BCI continuous index was significantly prognostic in the N0 subgroup for DRFI (n = 1110; P = .004), with 12-year DRFI of 95.9%, 90.8%, and 86.3% in BCI low-risk, intermediate-risk, and high-risk N0 cancers, respectively.

Conclusions and Relevance

In this prospective-retrospective translational study of patients enrolled in SOFT, BCI was confirmed as prognostic in premenopausal women with HR+ breast cancer. The benefit from OFS-containing adjuvant endocrine therapy was greater for patients with BCI(H/I)-low tumors than BCI(H/I)-high tumors. BCI(H/I)-low status may identify premenopausal patients who are likely to benefit from this more intensive endocrine therapy.

Pan-cancer analysis of homeodomain-containing gene C10 and its carcinogenesis in lung adenocarcinoma

We found elevated homeodomain-containing gene C10 (HOXC10) showed dual roles in cancers' prognosis. Some signal pathways associated with tumor were totally positively enriched in HOXC10 for whole cancers. On the contrary, Notch signaling, Wnt-beta catenin signaling, myogenesis, and Hedgehog signaling were almost negatively enriched in HOXC10. Some pathways showed dual roles such as Kras signaling, interferon gram and alpha response, IL6/JAK/STAT3, IL2/STAT5 signaling. HOXC10 was associated with tumor mutation burden and microsatellite instability. HOXC10 also was associated with tumor microenvironment and immune status. HOXC10 was negatively associated with immune score in most cancers except colon adenocarcinoma. The correlations of HOXC10 with immune-related genes presented dual roles in different cancers. Results from our clinical samples indicated that HOXC10 was an independent predictor for distant metastasis-free survival in lung adenocarcinoma (LUAD). Notably, the high levels of HOXC10 were positively correlated with the expression of angiogenic markers, vascular endothelial growth factor and microvessel density, and the number of CTC clusters. Our results demonstrated that aberrant expression happened in most cancers, which also affected the clinical prognosis and involved in progression via multiple signal pathways cancers. HOXC10 overexpression plays an important role in the aggression and metastasis in LUAD, which indicated a potential therapeutic target and an independent factor for the prognosis for LUAD patients.

Excessive activation of HOXB13/PIMREG axis promotes hepatocellular carcinoma progression and drug resistance

The transcription factor HOXB13 is bound up with the occurrence, progression and drug fast of many kinds of cancer. Nevertheless, the specific molecular mechanism of HOXB13 in hepatocellular carcinoma (HCC) is still unknown. This provides an obstacle to the exploration of HCC treatments targeting HOXB13. This study found that HOXB13 was up-regulated in HCC tissues. HOXB13 enhanced the multiplication and metastasis of HCC cells. It enhanced HCC cell drug and anoikis resistance. The analysis of HCC RNA seq data indicated that the expression of HOXB13 and PIMREG were positively correlated. Luciferase report assay showed that HOXB13 could activate PIMREG promoter transcription. The results of RT-qPCR and western blot showed that HOXB13 regulated the transcription of PIMREG. Western blot proved that high expression of PIMREG participated in DNA damage repair and cell cycle regulation by up-regulating RAD51, BRCA1, CDC25A, CDC25B and CDC25C and down-regulating HIPK2. This led to a significant increase in DNA repair capacity, accelerated cell cycle progression, and insensitive to DNA damage. Down-regulation of PIMREG in Hep3B cells overexpressing HOXB13 attenuated the phenotype induced by HOXB13. Therefore, HOXB13 functioned through PIMREG instead of directly regulating the transcription of RAD51, BRCA1, CDC25A, CDC25B and CDC25C. The same results were obtained in vivo. It was concluded that HOXB13 affected the expression of cell cycle and DNA repair related factors by up-regulating the transcription of PIMREG, thereby promoting the progression of HCC and enhancing the resistance of HCC to chemotherapeutics.

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.

Expression profile and prognostic significance of HOXB13 in rectal cancer

BACKGROUND

This study aimed to investigate the expression pattern and prognostic significance of HOXB13 in rectal cancer.

METHODS

HOXB13 expression in rectal cancer and normal adjacent tissues was detected by reverse transcriptase-polymerase chain reaction and immunohistochemistry, and its clinicopathological characteristics and prognosis were statistically tested. Furthermore, we evaluated the association between tumor immune infiltrating cells and HOXB13 using the tumor immune estimation resource (TIMER) database. The potential biological mechanism associated with HOXB13 overexpression was investigated by gene set enrichment analysis (GSEA).

RESULTS

The expression of HOXB13 messenger RNA and protein in human rectal cancer tissues were significantly higher than those in the normal adjacent tissues (P < 0.05). HOXB13 expression was significantly correlated with depth of invasion, lymphatic invasion, lymph node metastasis, distant metastasis, and pathological tumor node metastasis stage (P < 0.05). Kaplan-Meier survival curves confirmed that HOXB13 overexpression was correlated negatively with overall survival and disease-free survival in rectal cancer (P < 0.05). Also, multivariate Cox regression analysis demonstrated that HOXB13 expression, age, and lymphatic invasion were independent prognostic factors in rectal cancer (P < 0.05). Plus, the results from the TIMER database indicated that HOXB13 expression has a significant association with several immune cell infiltrates. Finally, the GSEA results indicated that HOXB13 participated in the various immune-associated processes, including natural killer cell-mediated cytotoxicity and the T-cell receptor signaling pathway.

CONCLUSION

Our study showed an essential role of HOXB13 in rectal cancer immunity and prognosis. Significantly, the overexpression of HOXB13 leads to the worse prognosis for patients with rectal cancer, which will contribute to understanding molecular mechanisms associated with tumor pathogenesis and prognosis in this disease.

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.

Identification of early diagnostic biomarkers via WGCNA in gastric cancer

BACKGROUND

Gastric cancer (GC) is the world's second-leading cause of cancer-related mortality, continuing to make it a serious healthcare concern. Even though the prevalence of GC reduces, the prognosis for GC patients remains poor in terms of a lack of reliable biomarkers to diagnose early GC and predict chemosensitivity and recurrence.

METHODS AND MATERIAL

We integrated the gene expression patterns of gastric cancers from four RNAseq datasets (GSE113255, GSE142000, GSE118897, and GSE130823) from Gene Expression Omnibus (GEO) database to recognize differentially expressed genes (DEGs) between normal and GC samples. A gene co-expression network was built using weighted co-expression network analysis (WGCNA). Furthermore, RT-qPCR was performed to validate the in silico results.

RESULTS

The red modules in GSE113255, Turquoise in GSE142000, Brown in GSE118897, and the green-yellow module in GSE130823 datasets were found to be highly correlated with the anatomical site of GC. ITGAX, CCL14, ADHFE1, and HOXB13) as the hub gene are differentially expressed in tumor and non-tumor gastric tissues in this study. RT-qPCR demonstrated a high level of the expression of this gene.

CONCLUSION

The expression levels of ITGAX, CCL14, ADHFE1, and HOXB13 in GC tumor tissues are considerably greater than in adjacent normal tissues. Systems biology approaches identified that these genes could be possible GC marker genes, providing ideas for other experimental studies in the future.

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.

Dysregulated tumor-associated macrophages in carcinogenesis, progression and targeted therapy of gynecological and breast cancers

Gynecological and breast cancers are a group of heterogeneous malignant tumors. Although existing treatment strategies have ameliorated the clinical outcomes of patients, the overall survival rate of advanced diseases remains unsatisfactory. Increasing evidence has indicated that the development and prognosis of tumors are closely related to the tumor microenvironment (TME), which restricts the immune response and provokes malignant progression. Tumor-associated macrophages (TAMs) are the main component of TME and act as a key regulator in tumor metastasis, immunosuppression and therapeutic resistance. Several preclinical trials have studied potential drugs that target TAMs to achieve potent anticancer therapy. This review focuses on the various functions of TAMs and how they influence the carcinogenesis of gynecological and breast cancers through regulating cancer cell proliferation, tumor angiogenesis and tumor-related immunosuppression. Besides, we also discuss the potential application of disabling TAMs signaling as a part of cancer therapeutic strategies, as well as CAR macrophages, TAMs-based vaccines and TAMs nanobiotechnology. These research advances support that targeting TAMs combined with conventional therapy might be used as effective therapeutics for gynecological and breast cancers in the future.

HOXA1 Is an Antagonist of ERα in Breast Cancer

Breast cancer is a heterogeneous disease and the leading cause of female cancer mortality worldwide. About 70% of breast cancers express ERα. HOX proteins are master regulators of embryo development which have emerged as being important players in oncogenesis. HOXA1 is one of them. Here, we present bioinformatic analyses of genome-wide mRNA expression profiles available in large public datasets of human breast cancer samples. We reveal an extremely strong opposite correlation between HOXA1 versus ER expression and that of 2,486 genes, thereby supporting a functional antagonism between HOXA1 and ERα. We also demonstrate in vitro that HOXA1 can inhibit ERα activity. This inhibition is at least bimodal, requiring an intact HOXA1 DNA-binding homeodomain and involving the DNA-binding independent capacity of HOXA1 to activate NF-κB. We provide evidence that the HOXA1-PBX interaction known to be critical for the transcriptional activity of HOXA1 is not involved in the ERα inhibition. Finally, we reveal that HOXA1 and ERα can physically interact but that this interaction is not essential for the HOXA1-mediated inhibition of ERα. Like other HOX oncoproteins interacting with ERα, HOXA1 could be involved in endocrine therapy resistance.

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.

ELOVL2: a novel tumor suppressor attenuating tamoxifen resistance in breast cancer

Epigenetic events have successfully explained the cause of various cancer types, but little is known about tamoxifen resistance (TamR) that induces cancer recurrence. In this study, via genome-wide methylation analysis in MCF-7/TamR cells we show that elongation of very-long chain fatty acid protein 2 (ELOVL2) was hypermethylated and downregulated in the samples from TamR breast cancer patients (n = 28) compared with those from Tam-sensitive (TamS) patients (n = 33) (P < 0.001). Strikingly, in addition to having tumor suppressor activity, ELOVL2 was shown to recover Tam sensitivity up to 70% in the MCF-7/TamR cells and in a xenograft mouse model. A group of genes in the AKT and ERa signaling pathways, e.g., THEM4, which play crucial roles in drug resistance, were found to be regulated by ELOVL2. This study implies that the deregulation of a gene in fatty acid metabolism can lead to drug resistance, giving insight into the development of a new therapeutic strategy for drug-resistant breast cancer.

HOXB13 promotes gastric cancer cell migration and invasion via IGF-1R upregulation and subsequent activation of PI3K/AKT/mTOR signaling pathway

AIMS

This study aimed at exploring HOXB13 expression and function in gastric cancer (GC), and the underlying molecular mechanism.

MATERIALS AND METHODS

HOXB13 and fat mass and obesity-associated protein (FTO) expression in GC and non-GC tissues of GC patients were analyzed using Gene Expression Profiling Interactive Analysis (GEPIA) and verified by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and western blotting. The regulatory relationship between FTO and HOXB13 was verified via RT-qPCR, methylated RNA immunoprecipitation sequencing (MeRIP-seq), and double luciferase reporter gene assay. The effects of HOXB13 and FTO on proliferation, invasion, and migration of GC cells were studied using EdU and Transwell assays.

KEY FINDINGS

HOXB13 and FTO expression was abnormally high in GC tissues and cell lines, with no significant correlation between HOXB13 and FTO expression and the prognosis of GC patients. Inhibiting FTO expression in GC cells decreased HOXB13 methylation and upregulated HOXB13 expression. Inhibiting HOXB13 and FTO expression suppressed GC cell proliferation, migration, and invasion. Decreased HOXB13 expression suppressed PI3K/AKT/mTOR signaling pathway activity, while atypical HOXB13 expression promoted it. A probable downstream target of HOXB13 was insulin-like growth factor 1 receptor (IGF-1R); a decrease in IGF-1R relieved GC cell migration, invasion, and proliferation and inhibited PI3K/AKT/mTOR signaling pathway activity promoted by atypical HOXB13 expression.

SIGNIFICANCE

HOXB13 and FTO expression is elevated in GC. FTO suppresses HOXB13 methylation; FTO and HOXB13 expression promotes GC cell proliferation, migration, and invasion. HOXB13 expression intensifies GC invasion through PI3K/AKT/mTOR signaling via IGF-1R. HOXB13 and associated signaling pathways can be effective targets for GC therapy.

A six-gene-based signature for breast cancer radiotherapy sensitivity estimation

Breast cancer (BRCA) represents the most common malignancy among women worldwide with high mortality. Radiotherapy is a prevalent therapeutic for BRCA that with heterogeneous effectiveness among patients. Here, we proposed to develop a gene expression-based signature for BRCA radiotherapy sensitivity estimation. Gene expression profiles of BRCA samples from the Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) were obtained and used as training and independent testing dataset, respectively. Differential expression genes (DEGs) in BRCA samples compared with their paracancerous samples in the training set were identified by using the edgeR Bioconductor package. Univariate Cox regression analysis and LASSO Cox regression method were applied to screen optimal genes for constructing a radiotherapy sensitivity estimation signature. Nomogram combining independent prognostic factors was used to predict 1-, 3-, and 5-year OS of radiation-treated BRCA patients. Relative proportions of tumor infiltrating immune cells (TIICs) calculated by CIBERSORT and mRNA levels of key immune checkpoint receptors was adopted to explore the relation between the signature and tumor immune response. As a result, 603 DEGs were obtained in BRCA tumor samples, six of which were retained and used to construct the radiotherapy sensitivity prediction model. The signature was proved to be robust in both training and testing sets. In addition, the signature was closely related to the immune microenvironment of BRCA in the context of TIICs and immune checkpoint receptors’ mRNA levels. In conclusion, the present study obtained a radiotherapy sensitivity estimation signature for BRCA, which should shed new light in clinical and experimental research.

Homeobox B5 promotes metastasis and poor prognosis in Hepatocellular Carcinoma, via FGFR4 and CXCL1 upregulation

Background: Since metastasis remains the main reason for HCC-associated death, a better understanding of molecular mechanism underlying HCC metastasis is urgently needed. Here, we elucidated the role of Homeobox B5 (HOXB5), a member of the HOX transcriptional factor family, in promoting HCC metastasis.

Method: The expression of HOXB5 and its functional targets fibroblast growth factor receptor 4 (FGFR4) and C-X-C motif chemokine ligand 1 (CXCL1) were detected by immunohistochemistry. Luciferase reporter and chromatin immunoprecipitation assays were performed to measure the transcriptional regulation of target genes by HOXB5. The effects of FGFR4 and CXCL1 on HOXB5-mediated metastasis were analyzed by an orthotopic metastasis model.

Results: Elevated expression of HOXB5 had a positive correlation with poor tumour differentiation, higher TNM stage, and indicated unfavorable prognosis. Overexpression of HOXB5 promoted HCC metastasis through transactivating FGFR4 and CXCL1 expression, whereas knockdown of FGFR4 and CXCL1 decreased HOXB5-enhanced HCC metastasis. Moreover, HOXB5 overexpression in HCC cells promoted myeloid derived suppressor cells (MDSCs) infiltration through CXCL1/CXCR2 axis. Either depletion of MDSCs by anti-Gr1 or blocking CXCL1-CXCR2 axis by CXCR2 inhibitor impaired HOXB5-mediated HCC metastasis. In addition, fibroblast growth factor 19 (FGF19) contributed to the HOXB5 upregulation through PI3K/AKT/HIF1α pathway. Overexpression of FGF15 (an analog of FGF19 in mouse) promoted HCC metastasis, whereas knockdown of HOXB5 significantly inhibited FGF15-enhanced HCC metastasis in immunocompetent mice. HOXB5 expression was positively associated with CXCL1 expression and intratumoral MDSCs accumulation in human HCC tissues. Patients who co-expressed HOXB5/CXCL1 or HOXB5/CD11b exhibited the worst prognosis. Furthermore, the combination of FGFR4 inhibitor BLU-554 and CXCR2 inhibitor SB265610 dramatically decreased HOXB5-mediated HCC metastasis.

Conclusion: HOXB5 was a potential prognostic biomarker in HCC patients and targeting this loop may provide a promising treatment strategy for the inhibition of HOXB5-mediated HCC metastasis.

Loss of 9p21 Regulatory Hub Promotes Kidney Cancer Progression by Upregulating HOXB13

Loss of chromosome 9p21 is observed in one-thirds of clear-cell renal cell carcinoma (ccRCC) and is associated with poorer patient survival. Unexpectedly, 9p21 LOH does not lead to decreased expression of the 9p21 tumor suppressor genes, CDKN2A and CDKN2B, suggesting alternative mechanisms of 9p-mediated tumorigenesis. Concordantly, CRISPR-mediated 9p21 deletion promotes growth of immortalized human embryonic kidney epithelial cells independently of the CDKN2A/B pathway inactivation. The 9p21 locus has a highly accessible chromatin structure, suggesting that 9p21 loss might contribute to kidney cancer progression by dysregulating genes distal to the 9p21 locus. We identified several 9p21 regulatory hubs by assessing which of the 9p21-interacting genes are dysregulated in 9p21-deleted kidney cells and ccRCCs. By focusing on the analysis of the homeobox gene 13 (HOXB13) locus, we found that 9p21 loss relieves the HOXB13 locus, decreasing HOXB13 methylation and promoting its expression. Upregulation of HOXB13 facilitates cell growth and is associated with poorer survival of patients with ccRCC. IMPLICATIONS: The results of our study propose a novel tumor suppressive mechanism on the basis of coordinated expression of physically associated genes, providing a better understanding of the role of chromosomal deletions in cancer.

Multiple roles of HOX proteins in Metastasis: Let me count the ways

Knowledge of the role of HOX proteins in cancer has been steadily accumulating in the last 25 years. They are encoded by 39 HOX genes arranged in 4 distinct clusters, and have unique and redundant function in all types of cancers. Many HOX genes behave as oncogenic transcriptional factors regulating multiple pathways that are critical to malignant progression in a variety of tumors. Some HOX proteins have dual roles that are tumor-site specific, displaying both oncogenic and tumor suppressor function. The focus of this review is on how HOX proteins contribute to growth or suppression of metastasis. The review will cover HOX protein function in the critical aspects of epithelial-mesenchymal transition, in cancer stem cell sustenance and in therapy resistance, manifested as distant metastasis. The emerging role of adiposity in both initiation and progression of metastasis is described. Defining the role of HOX genes in the metastatic process has identified candidates for targeted cancer therapies that may combat the metastatic process. We will discuss potential therapeutic opportunities, particularly in pathways influenced by HOX proteins.

Comprehensive analysis of the homeobox family genes in breast cancer demonstrates their similar roles in cancer and development

BACKGROUND

The homeobox (HOX) family consists of 39 genes whose expressions are tightly controlled and coordinated within the family, during development. We performed a comprehensive analysis of this gene family in cancer settings.

METHODS

Gene correlation analysis was performed using breast cancer data available in The Cancer Genome Atlas (TCGA) and data from the patients admitted to our hospital. We also analyzed the data of normal breast tissue (GSE20437). We next collected gene expression and prognosis data of breast cancer patients (GSE11121, GSE7390, GSE3494, and GSE2990) and performed unsupervised hierarchal clustering by the HOX gene expression pattern and compared prognosis. We additionally performed this analysis to leukemia (available in TCGA) and sarcoma (GSE20196) data.

RESULTS

Gene correlation analysis showed that the proximal HOX genes exhibit strong interactions and are expressed together in breast cancer, similar to the expression observed during development. However, in normal breast tissue, less interactions were observed. Breast cancer microarray meta-data classified by the HOX gene expression pattern predicted the prognosis of luminal B breast cancer patients (p = 0.016). Leukemia (p = 0.00016) and sarcoma (p = 0.018) presented similar results. The Wnt signaling pathway, one of the major upstream signals of HOX genes in development, was activated in the poor prognostic group. Interestingly, poor prognostic cancer presented stronger correlation in the gene family compared to favorable prognostic cancer.

CONCLUSION

Comprehensive analysis of the HOX family demonstrated their similar roles in cancer and development, and indicated that the strong interaction of HOX genes might be specific to malignancies, especially in the case of poor prognostic cancer.

A novel isoform of ATOH8 promotes the metastasis of breast cancer by regulating RhoC

Metastases are the main cause of cancer-related mortality in breast cancer. Although significant progress has been made in the field of tumor metastasis, the exact molecular mechanisms involved in tumor metastasis are still unclear. Here, we report that ATOH8-V1, a novel isoform of ATOH8, is highly expressed in breast cancer and is a negative prognostic indicator of survival for patients. Forced expression of ATOH8-V1 dramatically enhances, while silencing of ATOH8-V1 decreases the metastasis of breast cancer cell lines. Moreover, ATOH8-V1 directly binds to the RhoC promoter and stimulates the expression of RhoC, which in turn enhances the metastasis of breast cancer. Altogether, our data demonstrate that ATOH8-V1 is a novel pro-metastatic factor that enhances cancer metastasis, suggesting that ATOH8-V1 is a potential therapeutic target for treatment of metastatic cancers.

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.

ACK1-AR and AR-HOXB13 signaling axes: epigenetic regulation of lethal prostate cancers

The androgen receptor (AR) is a critical transcription factor in prostate cancer (PC) pathogenesis. Its activity in malignant cells is dependent on interactions with a diverse set of co-regulators. These interactions fluctuate depending on androgen availability. For example, the androgen depletion increases the dependence of castration-resistant PCs (CRPCs) on the ACK1 and HOXB13 cell survival pathways. Activated ACK1, an oncogenic tyrosine kinase, phosphorylates cytosolic and nuclear proteins, thereby avoiding the inhibitory growth consequences of androgen depletion. Notably, ACK1-mediated phosphorylation of histone H4, which leads to epigenetic upregulation of AR expression, has emerged as a critical mechanism of CRPC resistance to anti-androgens. This resistance can be targeted using the ACK1-selective small-molecule kinase inhibitor (R)- 9b. CRPCs also deploy the bromodomain and extra-terminal domain protein BRD4 to epigenetically increase HOXB13 gene expression, which in turn activates the MYC target genes AURKA/AURKB. HOXB13 also facilitates ligand-independent recruitment of the AR splice variant AR-V7 to chromatin, compensating for the loss of the chromatin remodeling protein, CHD1, and restricting expression of the mitosis control gene HSPB8. These studies highlight the crosstalk between AR-ACK1 and AR-HOXB13 pathways as key mediators of CRPC recurrence.

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.

Germline HOXB13 mutations p.G84E and p.R217C do not confer an increased breast cancer risk

In breast cancer, high levels of homeobox protein Hox-B13 (HOXB13) have been associated with disease progression of ER-positive breast cancer patients and resistance to tamoxifen treatment. Since HOXB13 p.G84E is a prostate cancer risk allele, we evaluated the association between HOXB13 germline mutations and breast cancer risk in a previous study consisting of 3,270 familial non-BRCA1/2 breast cancer cases and 2,327 controls from the Netherlands. Although both recurrent HOXB13 mutations p.G84E and p.R217C were not associated with breast cancer risk, the risk estimation for p.R217C was not very precise. To provide more conclusive evidence regarding the role of HOXB13 in breast cancer susceptibility, we here evaluated the association between HOXB13 mutations and increased breast cancer risk within 81 studies of the international Breast Cancer Association Consortium containing 68,521 invasive breast cancer patients and 54,865 controls. Both HOXB13 p.G84E and p.R217C did not associate with the development of breast cancer in European women, neither in the overall analysis (OR = 1.035, 95% CI = 0.859-1.246, P = 0.718 and OR = 0.798, 95% CI = 0.482-1.322, P = 0.381 respectively), nor in specific high-risk subgroups or breast cancer subtypes. Thus, although involved in breast cancer progression, HOXB13 is not a material breast cancer susceptibility gene.

Quantitative Analysis of Differential Expression of HOX Genes in Multiple Cancers

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

HOX genes function in Breast Cancer development

Breast cancer develops in the mammary glands during mammalian adulthood and is considered the second most common type of human carcinoma and the most incident and mortal in the female population. In contrast to other human structures, the female mammary glands continue to develop after birth, undergoing various modifications during pregnancy, lactation and involution under the regulation of hormones and transcription factors, including those encoded by the HOX clusters (A, B, C, and D). Interestingly, HOX gene deregulation is often associated to breast cancer development. Within the HOXB cluster, 8 out of the 10 genes present altered expression levels in breast cancer with an impact in its aggressiveness and resistance to hormone therapy, which highlights the importance of HOXB genes as potential therapeutic targets used to overcome the limitations of tamoxifen-resistant cancer treatments. Here, we review the current state of knowledge on the role of HOX genes in breast cancer, specially focus on HOXB, discussing the causes and consequences of HOXB gene deregulation and their relevance as prognostic factors and therapeutic targets.

The Nuclear Protein HOXB13 Enhances Methylmercury Toxicity by Inducing Oncostatin M and Promoting Its Binding to TNFR3 in Cultured Cells

Homeobox protein B13 (HOXB13), a transcription factor, is related to methylmercury toxicity; however, the downstream factors involved in enhancing methylmercury toxicity remain unknown. We performed microarray analysis to search for downstream factors whose expression is induced by methylmercury via HOXB13 in human embryonic kidney cells (HEK293), which are useful model cells for analyzing molecular mechanisms. Methylmercury induced the expression of oncostatin M (OSM), a cytokine of the interleukin-6 family, and this was markedly suppressed by HOXB13 knockdown. OSM knockdown also conferred resistance to methylmercury in HEK293 cells, and no added methylmercury resistance was observed when both HOXB13 and OSM were knocked down. Binding of HOXB13 to the OSM gene promoter was increased by methylmercury, indicating the involvement of HOXB13 in the enhancement of its toxicity. Because addition of recombinant OSM to the medium enhanced methylmercury toxicity in OSM-knockdown cells, extracellularly released OSM was believed to enhance methylmercury toxicity via membrane receptors. We discovered tumor necrosis factor receptor (TNF) receptor 3 (TNFR3) to be a potential candidate involved in the enhancement of methylmercury toxicity by OSM. This toxicity mechanism was also confirmed in mouse neuronal stem cells. We report, for the first time, that HOXB13 is involved in enhancement of methylmercury toxicity via OSM-expression induction and that the synthesized OSM causes cell death by binding to TNFR3 extracellularly.

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.

HOXB7 mediates cisplatin resistance in esophageal squamous cell carcinoma through involvement of DNA damage repair

Background

DNA damage repair is an important mechanism of platinum resistance. HOXB7 is one member of HOX family genes, which are essential developmental regulators and frequently dysregulated in cancer. Recently, its relevance in chemotherapy resistance and DNA damage repair has also been addressed. However, little is known regarding the association between HOXB7 and chemotherapy resistance in esophageal squamous cell carcinoma (ESCC).

Methods

The association between HOXB7 expression detected by immunohistochemisty and tumor regression grade (TRG) and long‐term survival was analyzed in 143 ESCC patients who underwent neoadjuvant chemotherapy. CCK8 assay was used to examine the effect of cisplatin in a panel of four ESCC cell lines. A stable cell strain with HOXB7 knockdown of KYSE150 and KYSE450 was established to explore the effect on cisplatin sensitivity. The interaction of HOXB7 with Ku70, Ku80 and DNA‐PKcs was determined by GST‐pull down, coimmunoprecipitation and immunofluorescent colocalization. Finally, we investigated whether disrupting HOXB7 function by a synthetic peptide HXR9 blocking the formation of HOXB7/PBX could enhance cisplatin sensitivity in vitro and in vivo.

Results

High expression of HOXB7 was associated with cisplatin resistance and worse chemotherapy efficacy. HOXB7 knockdown reinforced cisplatin sensitivity. It was identified that HOXB7 interacts with Ku70, Ku80 and DNA‐PKcs. HOXB7 knockdown was related to the downregulation of Ku70, Ku80 and DNA‐PKcs as well as arrested cell cycle in S phase. HOXB7 inhibition by HXR9 had a synergistic effect to improve cisplatin sensitivity.

Conclusion

HOXB7 may be a biomarker for the prediction of chemoresistance of ESCC and serves as a promising therapeutic target.

A Single MicroRNA-Hox Gene Module Controls Equivalent Movements in Biomechanically Distinct Forms of Drosophila

Movement is the main output of the nervous system. It emerges during development to become a highly coordinated physiological process essential to survival and adaptation of the organism to the environment. Similar movements can be observed in morphologically distinct developmental stages of an organism, but it is currently unclear whether or not these movements have a common molecular cellular basis. Here we explore this problem in Drosophila, focusing on the roles played by the microRNA (miRNA) locus miR-iab4/8, which we previously showed to be essential for the normal corrective response displayed by the fruit fly larva when turned upside down (self-righting). Our study shows that miR-iab4 is required for normal self-righting across all three Drosophila larval stages. Unexpectedly, we also discover that this miRNA is essential for normal self-righting behavior in the adult fly, an organism with different morphology, neural constitution, and biomechanics. Through the combination of gene expression, optical imaging, and quantitative behavioral approaches, we provide evidence that miR-iab4 exerts its effects on adult self-righting behavior in part through repression of the Hox gene Ultrabithorax (Ubx) in a specific set of adult motor neurons, the NB2-3/lin15 neurons. Our results show that miRNA controls the function, rather than the morphology, of these neurons and demonstrate that post-developmental changes in Hox gene expression can modulate behavior in the adult. Our work reveals that a common miRNA-Hox genetic module can be re-deployed in different neurons to control functionally equivalent movements in biomechanically distinct organisms and describes a novel post-developmental role of the Hox genes in adult neural function.

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The fruit fly miRNA gene miR-iab4 controls the same behavior in the larva and adult

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miR-iab4 exerts its behavioral roles via repression of the Hox gene Ultrabithorax

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miRNA/Hox inputs affect the physiology and not the anatomy of specific motor neurons

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Conditional expression shows a novel role of the Hox genes in adult neural function

Targeting the circBMPR2/miR-553/USP4 Axis as a Potent Therapeutic Approach for Breast Cancer

Emerging evidence suggests that circular RNAs (circRNAs) have crucial roles in various processes, including cancer development and progression. However, the functional roles of circRNAs in breast cancer remain to be elucidated. In this study, we identified a novel circRNA (named circBMPR2) whose expression was lower in breast cancer tissues with metastasis. Moreover, circBMPR2 expression was negatively associated with the motility of breast cancer cells and significantly downregulated in human breast cancer tissues. Functionally, we found that circBMPR2 knockdown effectively enhanced cell proliferation, migration, and invasion. Moreover, circBMPR2 knockdown promoted tamoxifen resistance of breast cancer cells through inhibiting tamoxifen-induced apoptosis, whereas circBMPR2 overexpression led to decreased tamoxifen resistance. Mechanistically, we demonstrated that circBMPR2 could abundantly sponge miR-553 and that miR-553 overexpression could attenuate the inhibitory effects caused by circBMPR2 overexpression. We also found that ubiquitin-specific protease 4 (USP4) was a direct target of miR-553, which functions as a tumor suppressor in breast cancer. Our findings demonstrated that circBMPR2 might function as a miR-553 sponge and then relieve the suppression of USP4 to inhibit the progression and tamoxifen resistance of breast cancer. Targeting this newly identified circRNA may help us to develop potential novel therapies for breast cancer patients.

Paralogous HOX13 Genes in Human Cancers

Hox genes (HOX in humans), an evolutionary preserved gene family, are key determinants of embryonic development and cell memory gene program. Hox genes are organized in four clusters on four chromosomal loci aligned in 13 paralogous groups based on sequence homology (Hox gene network). During development Hox genes are transcribed, according to the rule of “spatio-temporal collinearity”, with early regulators of anterior body regions located at the 3’ end of each Hox cluster and the later regulators of posterior body regions placed at the distal 5’ end. The onset of 3’ Hox gene activation is determined by Wingless-type MMTV integration site family (Wnt) signaling, whereas 5’ Hox activation is due to paralogous group 13 genes, which act as posterior-inhibitors of more anterior Hox proteins (posterior prevalence). Deregulation of HOX genes is associated with developmental abnormalities and different human diseases. Paralogous HOX13 genes (HOX A13, HOX B13, HOX C13 and HOX D13) also play a relevant role in tumor development and progression. In this review, we will discuss the role of paralogous HOX13 genes regarding their regulatory mechanisms during carcinogenesis and tumor progression and their use as biomarkers for cancer diagnosis and treatment.

HOXB13 promotes proliferation, migration, and invasion of glioblastoma through transcriptional upregulation of lncRNA HOXC-AS3

HOXB13 exerts a close relation in several human cancers. This study explored the role of HOXB13 in glioblastoma (GBM), a brain tissue with the highest aggressive rate and mortality in adults. Through microarray and immunohistochemistry analyses, HOXB13 was highly expressed in GBM tissues. Furthermore, we showed that high-level expression of HOXB13 in GBM was associated with worse survival, suggesting that HOXB13 could be a prognostic marker for patients with GBM. GBM cells U87 and U251 overexpressing HOXB13 showed enhanced proliferation, migration, and invasion relative to the control cells, while knockdown of HOXB13 led to decreased cell proliferation, migration, and invasion abilities. In addition, dual-luciferase report assay, chromatin immunoprecipitation assay, and quantitative real-time polymerase chain reaction data showed that HOXB13 directly bound to HOXC-AS3 promoter. HOXC-AS3 was involved in HOXB13-induced proliferation, migration, and invasion of GBM cells. In summary, this study revealed the prognostic potential of HOXB13 in GBM. We believed that HOXB13/HOXC-AS3 signaling axis can be served as therapeutic targets for this highly aggressive cancer.

HOXB13 networking with ABCG1/EZH2/Slug mediates metastasis and confers resistance to cisplatin in lung adenocarcinoma patients

Rationale: Distant metastasis and chemoresistance are the major causes of short survival after initial chemotherapy in lung adenocarcinoma patients. However, the underlying mechanisms remain elusive. Our pilot study identified high expression of the homeodomain transcription factor HOXB13 in chemoresistant lung adenocarcinomas. We aimed to investigate the role of HOXB13 in mediating lung adenocarcinoma chemoresistance.

Methods: Immunohistochemistry assays were employed to assess HOXB13 protein levels in 148 non-small cell lung cancer patients. The role of HOXB13 in lung adenocarcinoma progression and resistance to cisplatin therapy was analyzed in cells, xenografted mice, and patient-derived xenografts. Needle biopsies from 15 lung adenocarcinoma patients who were resistant to cisplatin and paclitaxel therapies were analyzed for HOXB13 and EZH2 protein levels using immunohistochemistry.

Results: High expression of HOXB13 observed in 17.8% of the lung adenocarcinoma patients in this study promoted cancer progression and predicted poor prognosis. HOXB13 upregulated an array of metastasis- and drug-resistance-related genes, including ABCG1, EZH2, and Slug, by directly binding to their promoters. Cisplatin induced HOXB13 expression in lung adenocarcinoma cells, and patient-derived xenografts and depletion of ABCG1 enhanced the sensitivity of lung adenocarcinoma cells to cisplatin therapy. Our results suggest that determining the combined expression of HOXB13 and its target genes can predict patient outcomes.

Conclusions: A cisplatin-HOXB13-ABCG1/EZH2/Slug network may account for a novel mechanism underlying cisplatin resistance and metastasis after chemotherapy. Determining the levels of HOXB13 and its target genes from needle biopsy specimens may help predict the sensitivity of lung adenocarcinoma patients to platinum-based chemotherapy and patient outcomes.

Up-regulation of HOXB cluster genes are epigenetically regulated in tamoxifen-resistant MCF7 breast cancer cells

Tamoxifen (TAM) is commonly used to treat estrogen receptor (ER)-positive breast cancer. Despite the remarkable benefits, resistance to TAM presents a serious therapeutic challenge. Since several HOX transcription factors have been proposed as strong candidates in the development of resistance to TAM therapy in breast cancer, we generated an in vitro model of acquired TAM resistance using ER-positive MCF7 breast cancer cells (MCF7-TAMR), and analyzed the expression pattern and epigenetic states of HOX genes. HOXB cluster genes were uniquely up-regulated in MCF7-TAMR cells. Survival analysis of in slico data showed the correlation of high expression of HOXB genes with poor response to TAM in ER-positive breast cancer patients treated with TAM. Gain- and loss-of-function experiments showed that the overexpression of multi HOXB genes in MCF7 renders cancer cells more resistant to TAM, whereas the knockdown restores TAM sensitivity. Furthermore, activation of HOXB genes in MCF7-TAMR was associated with histone modifications, particularly the gain of H3K9ac. These findings imply that the activation of HOXB genes mediate the development of TAM resistance, and represent a target for development of new strategies to prevent or reverse TAM resistance.

Roles of Small GTPases in Acquired Tamoxifen Resistance in MCF-7 Cells Revealed by Targeted, Quantitative Proteomic Analysis

Development of tamoxifen resistance remains a tremendous challenge for the treatment of estrogen-receptor (ER)-positive breast cancer. Small GTPases of the Ras superfamily play crucial roles in intracellular trafficking and cell signaling, and aberrant small-GTPase signaling is implicated in many types of cancer. In this study, we employed a targeted, quantitative proteomic approach that relies on stable-isotope labeling by amino acids in cell culture (SILAC), gel fractionation, and scheduled multiple-reaction-monitoring (MRM) analysis, to assess the differential expression of small GTPases in MCF-7 and the paired tamoxifen-resistant breast cancer cells. The method displayed superior sensitivity and reproducibility over the shotgun-proteomic approach, and it facilitated the quantification of 96 small GTPases. Among them, 13 and 10 proteins were significantly down- and up-regulated (with >1.5-fold change), respectively, in the tamoxifen-resistant line relative to in the parental line. In particular, we observed a significant down-regulation of RAB31 in tamoxifen-resistant cells, which, in combination with bioinformatic analysis and downstream validation experiments, supported a role for RAB31 in tamoxifen resistance in ER-positive breast-cancer cells. Together, our results demonstrated that the targeted proteomic method constituted a powerful approach for revealing the role of small GTPases in therapeutic resistance.

Targeting the BRD4-HOXB13 Coregulated Transcriptional Networks with Bromodomain-Kinase Inhibitors to Suppress Metastatic Castration-Resistant Prostate Cancer

Resistance to androgen receptor (AR) antagonists is a significant problem in the treatment of castration-resistant prostate cancers (CRPC). Identification of the mechanisms by which CRPCs evade androgen deprivation therapies (ADT) is critical to develop novel therapeutics. We uncovered that CRPCs rely on BRD4-HOXB13 epigenetic reprogramming for androgen-independent cell proliferation. Mechanistically, BRD4, a member of the BET bromodomain family, epigenetically promotes HOXB13 expression. Consistently, genetic disruption of HOXB13 or pharmacological suppression of its mRNA and protein expression by the novel dual-activity BET bromodomain-kinase inhibitors directly correlates with rapid induction of apoptosis, potent inhibition of tumor cell proliferation and cell migration, and suppression of CRPC growth. Integrative analysis revealed that the BRD4-HOXB13 transcriptome comprises a proliferative gene network implicated in cell-cycle progression, nucleotide metabolism, and chromatin assembly. Notably, although the core HOXB13 target genes responsive to BET inhibitors (HOTBIN10) are overexpressed in metastatic cases, in ADT-treated CRPC cell lines and patient-derived circulating tumor cells (CTC) they are insensitive to AR depletion or blockade. Among the HOTBIN10 genes, AURKB and MELK expression correlates with HOXB13 expression in CTCs of mCRPC patients who did not respond to abiraterone (ABR), suggesting that AURKB inhibitors could be used additionally against high-risk HOXB13-positive metastatic prostate cancers. Combined, our study demonstrates that BRD4-HOXB13-HOTBIN10 regulatory circuit maintains the malignant state of CRPCs and identifies a core proproliferative network driving ADT resistance that is targetable with potent dual-activity bromodomain-kinase inhibitors.

BP1, a potential biomarker for breast cancer prognosis

Homeobox genes are critical in tumor development. An isoform protein of DLX4 called BP1 is expressed in 80% of invasive ductal breast carcinomas. BP1 overexpression is implicated in an aggressive phenotype and poor prognosis. BP1 upregulation is associated with estrogen receptor negativity so those tumors do not respond to antiestrogens. Breast cancer is the second leading cause of death in women. BP1 could serve as both a novel prognostic biomarker for breast cancer and a therapeutic target. In this review, we address the role of BP1 protein in tumorigenesis of breast cancer and four other malignancies. A number of functions of BP1 in cancer are also discussed.

Cytokine-mediated therapeutic resistance in breast cancer

Therapeutic resistance leading to tumor relapse is a major challenge in breast cancer (BCa) treatment. Numerous factors involved in multiple mechanisms promote the development of tumor chemo/radio-resistance. Cytokines/chemokines are important inflammatory factors and highly related to tumorigenesis, metastasis and tumors responses to treatment. A large number of studies have demonstrated that the network of cytokines activates multiple cell signaling pathways to promote tumor cell survival, proliferation, invasion, and migration. Particularly in BCa, cytokines-enhanced the epithelial-mesenchymal transition (EMT) process plays a pivotal role in the progression of metastatic phenotypes and resistance to the traditional chemo/radio-therapy. Virtually, therapeutic resistance is not entirely determined by tumor cell intrinsic characteristics but also dependent upon synchronized effects by numerous of local microenvironmental factors. Emerging evidence highlighted that exosomes secreted from various types of cells promote intercellular communication by transferring bioactive molecules including miRNAs and cytokines, suggesting that exosomes are essential for sustentation of tumor progression and therapeutic resistance within the tumor microenvironment. In this review, we discuss the mechanisms by which cytokines promote therapeutic resistance of BCa and suggest a potential approach for improving BCa therapeutics by inhibition of exosome function.

Expression signatures of HOX cluster genes in cervical cancer pathogenesis: Impact of human papillomavirus type 16 oncoprotein E7

The Homeobox (HOX) genes encode important transcription factors showing deregulated expression in several cancers. However, their role in cervical cancer pathogenesis, remains largely unexplored. Herein, we studied their association with Human Papillomavirus type 16 (HPV16) mediated cervical cancers. Our previously published gene expression microarray data revealed a significant alteration of 12 out of 39 HOX cluster members among cervical cancer cases, in comparison to the histopathologically normal controls. Of these, we validated seven (HOXA10, HOXA13, HOXB13, HOXC8, HOXC9, HOXC11 and HOXD10) by quantitative real-time PCR. We identified decreased HOXA10 expression as opposed to the increased expression of the rest. Such decrease was independent of the integration status of HPV16 genome, but correlated negatively with E7 expression in clinical samples, that was confirmed in vitro. HOXA10 and HOXB13 revealed association with Epithelial-Mesenchymal Transition (EMT). While HOXA10 expression correlated positively with E-Cadherin and negatively with Vimentin expression, HOXB13 showed the reverse trend. Chromatin immunoprecipitation study in vitro revealed the ability of E7 to increase HOX gene expression by epigenetic regulation, affecting the H3K4me3 and H3K27me3 status of their promoters, resulting from a loss of PRC2-LSD1 complex activity. Thus, besides identifying the deregulated expression of HOX cluster members in HPV16 positive cervical cancer and their association with EMT, our study highlighted the mechanism of HPV16 E7-mediated epigenetic regulation of HOX genes in such cancers, potentially serving as bedrock for functional studies in the future.

Oncoprotein HBXIP enhances HOXB13 acetylation and co-activates HOXB13 to confer tamoxifen resistance in breast cancer

Background

Resistance to tamoxifen (TAM) frequently occurs in the treatment of estrogen receptor positive (ER+) breast cancer. Accumulating evidences indicate that transcription factor HOXB13 is of great significance in TAM resistance. However, the regulation of HOXB13 in TAM-resistant breast cancer remains largely unexplored. Here, we were interested in the potential effect of HBXIP, an oncoprotein involved in the acceleration of cancer progression, on the modulation of HOXB13 in TAM resistance of breast cancer.

Methods

The Kaplan-Meier plotter cancer database and GEO dataset were used to analyze the association between HBXIP expression and relapse-free survival. The correlation of HBXIP and HOXB13 in ER+ breast cancer was assessed by human tissue microarray. Immunoblotting analysis, qRT-PCR assay, immunofluorescence staining, Co-IP assay, ChIP assay, luciferase reporter gene assay, cell viability assay, and colony formation assay were performed to explore the possible molecular mechanism by which HBXIP modulates HOXB13. Cell viability assay, xenograft assay, and immunohistochemistry staining analysis were utilized to evaluate the effect of the HBXIP/HOXB13 axis on the facilitation of TAM resistance in vitro and in vivo.

Results

The analysis of the Kaplan-Meier plotter and the GEO dataset showed that mono-TAM-treated breast cancer patients with higher HBXIP expression levels had shorter relapse-free survivals than patients with lower HBXIP expression levels. Overexpression of HBXIP induced TAM resistance in ER+ breast cancer cells. The tissue microarray analysis revealed a positive association between the expression levels of HBXIP and HOXB13 in ER+ breast cancer patients. HBXIP elevated HOXB13 protein level in breast cancer cells. Mechanistically, HBXIP prevented chaperone-mediated autophagy (CMA)-dependent degradation of HOXB13 via enhancement of HOXB13 acetylation at the lysine 277 residue, causing the accumulation of HOXB13. Moreover, HBXIP was able to act as a co-activator of HOXB13 to stimulate interleukin (IL)-6 transcription in the promotion of TAM resistance. Interestingly, aspirin (ASA) suppressed the HBXIP/HOXB13 axis by decreasing HBXIP expression, overcoming TAM resistance in vitro and in vivo.

Conclusions

Our study highlights that HBXIP enhances HOXB13 acetylation to prevent HOXB13 degradation and co-activates HOXB13 in the promotion of TAM resistance of breast cancer. Therapeutically, ASA can serve as a potential candidate for reversing TAM resistance by inhibiting HBXIP expression.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0577-5) contains supplementary material, which is available to authorized users.

The effect of lncRNA HOTAIR on chemoresistance of ovarian cancer through regulation of HOXA7

This study aimed at investigating the biological functions of long non-coding RNAs (lncRNAs) hox transcript antisense intergenic RNA (HOTAIR) in resistant ovarian cancer cells, exploring the regulation effect of HOTAIR on HOXA7, and investigating their influence on the chemosensitivity of ovarian cancer cells. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied for the verification of HOTAIR expression in resistant and sensitive groups. How HOTAIR downregulation affected cell proliferation, migration and invasion, and apoptosis were determined using the MTT assay and the colony formation assay, the Transwell assay and flow cytometry analysis, respectively. Immunohistochemistry was used to inspect the protein expression of HOXA7 in resistant and sensitive ovarian cancer tissues. The regulation relationship between HOTAIR and HOXA7 was investigated by qRT-PCR and Western blot. The effect of HOTAIR and HOXA7 on tumor growth was confirmed by the tumor xenograft model of nude mice. By knocking down HOXA7, HOTAIR downregulation restrained the ovarian cancer deterioration in functional experiments. Silencing of HOTAIR and HOXA7 could effectively inhibit tumor growth and increase chemosensitivity of ovarian tumors in nude mice. Downregulation of HOTAIR negatively affected the survival and activity of resistant ovarian cancer cells, and suppressed the expression of HOXA7. Silencing of HOTAIR and HOXA7 could increase the chemosensitivity of ovarian cancer cells, thus suppressing tumor development.

The posterior HOXD locus: Its contribution to phenotype and malignancy of Ewing sarcoma

Microarray analysis revealed genes of the posterior HOXD locus normally involved in bone formation to be over-expressed in primary Ewing sarcoma (ES). The expression of posterior HOXD genes was not influenced via ES pathognomonic EWS/ETS translocations. However, knock down of the dickkopf WNT signaling pathway inhibitor 2 (DKK2) resulted in a significant suppression of HOXD10, HOXD11 and HOXD13 while over-expression of DKK2 and stimulation with factors of the WNT signaling pathway such as WNT3a, WNT5a or WNT11 increased their expression. RNA interference demonstrated that individual HOXD genes promoted chondrogenic differentiation potential, and enhanced expression of the bone-associated gene RUNX2. Furthermore, HOXD genes increased the level of the osteoblast- and osteoclast-specific genes, osteocalcin (BGLAP) and platelet-derived growth factor beta polypeptide (PDGFB), and may further regulate endochondral bone development via induction of parathyroid hormone-like hormone (PTHLH). Additionally, HOXD11 and HOXD13 promoted contact independent growth of ES, while in vitro invasiveness of ES lines was enhanced by all 3 HOXD genes investigated and seemed mediated via matrix metallopeptidase 1 (MMP1). Consequently, knock down of HOXD11 or HOXD13 significantly suppressed lung metastasis in a xeno-transplant model in immune deficient mice, providing overall evidence that posterior HOXD genes promote clonogenicity and metastatic potential of ES.

Potential therapeutic implications of IL-6/IL-6R/gp130-targeting agents in breast cancer

Interleukin-6 (IL-6) is a pleiotropic cytokine with known multiple functions in immune regulation, inflammation, and oncogenesis. Binding of IL-6 to the IL-6 receptor (IL-6R) induces homodimerization and recruitment of glycoprotein 130 (gp130), which leads to activation of downstream signaling. Emerging evidence suggests that high levels of IL-6 are correlated with poor prognosis in breast cancer patients. IL-6 appears to play a critical role in the growth and metastasis of breast cancer cells, renewal of breast cancer stem cells (BCSCs), and drug resistance of BCSCs, making anti-IL-6/IL-6R/gp130 therapies promising options for the treatment and prevention of breast cancers. However, preclinical and clinical studies of the applications of anti-IL-6/IL-6R/gp130 therapy in breast cancers are limited. In this review, we summarize the structures, preclinical and clinical studies, mechanisms of action of chemical and biological blockers that directly bind to IL-6, IL-6R, or gp130, and the potential clinical applications of these pharmacological agents as breast cancer therapies.

Hox-Mediated Spatial and Temporal Coding of Stem Cells in Homeostasis and Neoplasia

Hox genes are fundamental components of embryonic patterning and morphogenesis with expression persisting into adulthood. They are also implicated in the development of diseases, particularly neoplastic transformations. The tight spatio-temporal regulation of Hox genes in concordance with embryonic patterning is an outstanding feature of these genes. In this review we have systematically analyzed Hox functions within the stem/progenitor cell compartments and asked whether their temporo-spatial topography is retained within the stem cell domain throughout development and adulthood. In brief, evidence support involvement of Hox genes at several levels along the stem cell hierarchy, including positional identity, stem cell self-renewal, and differentiation. There is also strong evidence to suggest a role for Hox genes during neoplasia. Although fundamental questions are yet to be addressed through more targeted and high- throughput approaches, existing evidence suggests a central role for Hox genes within a continuum along the developmental axes persisting into adult homeostasis and disease.

Increased HOXC6 expression predicts chemotherapy sensitivity in patients with esophageal squamous cell carcinoma

Increased expression of homeobox C6 (HOXC6) predicts poor prognosis of patients with esophageal squamous cell carcinoma (ESCC) and promotes ESCC cell proliferation. Additionally, the expression of HOXC6 was upregulated in chemosensitive ESCC cell lines. Therefore, it was hypothesized that HOXC6 may be associated with chemosensitivity of ESCC. Patients with ESCC who underwent neoadjuvant chemotherapy followed by surgery by a single-surgeon team between January 2000 and December 2012 were enrolled in the present study. Pretreatment biopsy specimens and postoperative resection samples were collected. Immunohistochemistry was performed to examine HOXC6 expression, and the association between HOXC6 expression and tumor regression grade (TRG) was analyzed. In cell lines exhibiting stable knockdown of HOXC6, Cell Counting Kit-8 assays were used to evaluate the chemosensitivity of cells to various concentrations of cisplatin and paclitaxel. A total of 51 pretreatment biopsy specimens were assessed, and patients with increased expression of HOXC6 in pretreatment biopsy specimens exhibited higher TRGs. A total of 186 surgical samples were evaluated; HOXC6 was expressed at a decreased level in patients with higher TRG and at a high level in patients with lower TRG. In addition, downregulation of HOXC6 decreased the sensitivity of ESCC cell lines to cisplatin and paclitaxel, resulting in an increased half-maximal inhibitory concentration. Increased expression of HOXC6 prior to treatment was associated with chemosensitivity in ESCC tissues.