A serologically identified tumor antigen encoded by a homeobox gene promotes growth of ovarian epithelial cells

Integrated Bioinformatic Analysis of the Correlation of HOXA10 Expression with Survival and Immune Cell Infiltration in Lower Grade Glioma

Homeobox A10 (HOXA10) encodes a transcription factor that regulates developmental processes. Whether HOXA10 mRNA levels in lower grade glioma (LGG) correlate with survival and immune cell infiltration has not been evaluated. The differential expression of HOXA10 in different tumors and their corresponding normal tissues was evaluated by exploring public datasets. The correlations between HOXA10 and survival, tumor immune cell infiltration, diverse gene mutation characteristics, and tumor mutation burden in LGG were also investigated using several independent datasets. Pathway enrichment analysis was conducted to identify HOXA10-associated signaling pathways. We found that HOXA10 expression levels did not significantly differ between LGG tumors and normal tissues. Upon assessing the association between HOXA10 expression and immune cell infiltration in LGG, as expected, HOXA10 gene mRNA levels were positively associated with B-cell and dendritic cell infiltration levels in public online datasets. Different HOXA10 expression groups showed diverse gene mutation characteristics and TMB, and low HOXA10 expression was closely related to improved LGG patient survival. Pathway enrichment analysis of HOXA10-associated genes indicated that the cell cycle signaling pathway may participate in affecting the outcomes of LGG patients. Our findings showed that HOXA10 expression was associated with LGG prognosis and tumor immunity.

Cell Cycle-Related Gene SPC24: A Novel Potential Diagnostic and Prognostic Biomarker for Laryngeal Squamous Cell Cancer

Laryngeal squamous cell cancer (LSCC) is a common malignant tumor with a high degree of malignancy, and its etiology remains unclear. Therefore, screening potential biomarkers is necessary to facilitate the treatment and diagnosis of LSCC. Robust rank aggregation (RRA) analysis was used to integrate two gene expression datasets of LSCC patients from the Gene Expression Omnibus (GEO) database and identify differentially expressed genes (DEGs) between LSCC and nonneoplastic tissues. A gene coexpression network was constructed using weighted gene correlation network analysis (WGCNA) to explore potential associations between the module genes and clinical features of LSCC. Combining differential gene expression analysis and survival analysis, we screened potential hub genes, including CDK1, SPC24, HOXB7, and SELENBP1. Subsequently, western blotting and immunohistochemistry were used to test the protein levels in clinical specimens to verify our findings. Finally, four candidate diagnostic and prognostic biomarkers (CDK1, SPC24, HOXB7, and SELENBP1) were identified. We propose, for the first time, that SPC24 is a gene that may associate with LSCC malignancy and is a novel therapeutic target. These findings may provide important mechanistic insight of LSCC.

Mitogen-activated protein kinase inhibition augments the T cell response against HOXB7-expressing tumor through human leukocyte antigen upregulation

Homeobox B7 (HOXB7) is a master regulatory gene that regulates cell proliferation and activates oncogenic pathways. Overexpression of HOXB7 correlates with aggressive behavior and poor prognosis in patients with cancer. However, the expression and role of HOXB7 in head and neck squamous cell carcinoma (HNSCC) remain unclear. In this study, we observed that most samples from patients with oropharyngeal cancer and HNSCC expressed HOXB7. As no direct inhibitor has been reported, we identified a potent peptide epitope to target HOXB7-expressing tumors through immune cells. A novel HOXB7-derived peptide epitope (HOXB7_8-25 ) elicited antigen-specific and tumor-reactive promiscuous CD4⁺ T cell responses. These CD4⁺ T cells produced γ-interferon (IFN-γ) and had the direct ability to kill tumors through granzyme B. Notably, downregulation of HOXB7 using siRNA enhanced human leukocyte antigen class II expression on tumor cells by decreasing the phosphorylation of MAPK. Mitogen-activated protein kinase inhibition augmented IFN-γ production by HOXB7-reactive CD4⁺ T cell responses without decreasing the expression of HOXB7. These results suggest that combining HOXB7 peptide-based vaccine with MAPK inhibitors could be an effective immunological strategy for cancer treatment.

High expression of HOXB7 is an unfavorable prognostic factor for solid malignancies: A meta-analysis

BACKGROUND

HOXB7 is abnormally expressed in a variety of tumors, but its prognostic value remains unclear due to sample size limitation and outcome inconsistency in previous studies. This meta-analysis was performed to explore the effect of HOXB7 expression on prognoses and clinicopathological factors in range of the whole solid tumors.

METHODS

PubMed, EMBASE, and Web of Science databases were searched to identify included studies. Hazard ratios (HR) with its 95% confidence interval (CI) and clinicopathological factors were extracted. Subgroup analyses were performed according to histopathological type, tumor occurrence systems, and HOXB7 detection methods.

RESULTS

A total of 3430 solid tumors patients from 20 studies (21 cohorts) were included in the meta-analysis. The results showed that high HOXB7 expression was significantly associated with worse survival (overall survival: HR = 1.98, 95%CI: 1.74-2.26, P < .001 and disease-free survival: HR = 1.59, 95%CI: 1.21-2.09, P = .001), more advanced tumor-node-metastasis (TNM) stage (odds ratio [OR] = 2.14, 95%CI: 1.68-2.73, P < .001), positive lymph node metastasis (OR = 2.16, 95%CI: 1.74-2.70, P < .001), more distant metastasis (OR = 1.63, 95%CI: 1.01-2.63, P = .048), poorer differentiation (OR = 1.48, 95%CI: 1.14-1.91, P = .003), and higher Ki-67 expression (OR = 2.53, 95%CI: 1.68-3.84, P < .001). Subgroup analysis showed that survival of patients with HOXB7 high expression was worse in either squamous cell carcinomas or non-squamous cell carcinomas, digestive tumors or non-digestive tumors, and protein level or mRNA level.

CONCLUSION

High HOXB7 expression might be a valuable biomarker of poor prognosis for solid tumors. HOXB7 promotes tumor proliferation and metastasis, and is associated with poorer differentiation, more advanced stage, even the chemotherapy resistance, suggesting that HOXB7 is a potential therapeutic target for solid tumors.

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.

HOX Genes in High Grade Ovarian Cancer

HOX genes are highly conserved members of the homeobox superfamily that have a crucial role in determining cellular identity. High grade ovarian cancer is the most lethal gynaecological malignancy. Our understanding of the role of HOX genes in the oncogenesis of ovarian cancer is evolving, and here we review their dysregulated expression patterns, their function in cell survival and invasion, their potential uses as biomarkers, and ways in which HOX genes are being targeted with new and existing drugs.

HOXA10 expression profiling in prostate cancer

BACKGROUND

HOX genes encode transcription factors that play key roles in modulating normal tissue morphogenesis, differentiation and homeostasis. Disruption of normal HOX gene expression occurs frequently in human cancers and is associated with both tumor promoting and suppressing activities. Among these is, HOXA10, a pleiotropic gene that is critical for normal prostate development. In this study we characterized HOXA10 expression in human and mouse PCa to gain insights into its clinical significance.

METHODS

A meta-analysis of HOXA10 mRNA expression was carried out across several publicly available data sets. Expression of HOXA10 protein expression was assessed by immunohistochemistry (IHC) using human radical prostatectomy (RP) cases. We correlated HOXA10 expression to clinicopathological features and investigated its relationship to biochemical recurrence (BCR) after RP by the Kaplan-Meier method. HOXA10 mRNA and IHC protein expression was also examined in a mouse model of Pten-null PCa.

RESULTS

A meta-analysis of HOXA10 gene expression indicated dysregulated expression of HOXA10 in human PCa. IHC profiling of HOXA10 revealed inverse correlations between HOXA10 expression and Gleason pattern, Gleason score, and pathological stage (P < 0.01). Patients with low expression profiles of HOXA10 were associated with a higher risk of BCR, (OR, 3.54; 95%CI, 1.21-16.14; P = 0.049) whereas patients with high HOXA10 expression experienced longer times to BCR (P = 0.045). However, HOXA10 was not an independent predictor of BCR (OR, 1.52; 95%CI, 0.42-5.54; P = 0.52). Evaluation of expression patterns of HOXA10 in mouse prostate tumors mimicked that of humans.

CONCLUSIONS

Our findings show that HOXA10 expression is inversely associated with tumor differentiation and high HOXA10 expression is associated with improved BCR-free survival. This study provides human and mouse evidence to suggest tumor suppressive roles for HOXA10 in the context of prostate cancer.

Down-regulation of DKK1 and Wnt1/β-catenin pathway by increased homeobox B7 resulted in cell differentiation suppression of intrauterine fetal growth retardation in human placenta

OBJECTIVE

This study aimed to test the influence of homeobox B7 (HoxB7) on the proliferation, invasion, and migration of human trophoblast cells and to reveal the down-regulation of HoxB7 on the transcriptional suppression of Dick Kopf-related protein1 (DKK1) and of Cysteine-rich glycosylated wingless protein 1 (Wnt1)/β-catenin in intrauterine fetal growth retardation (FGR).

METHODS

Quantitative measurement of HoxB7, DKK1, Wnt1, and β-catenin was performed in human placentas collected from normal pregnancies and from FGR with quantitative real time PCR (qRT-PCR). Cultured HTR-8/SVneo cells, transfected with a lentiviral plasmid that in-frame expresses human HoxB7 gene, were applied to functional assessment to study the biological impact of HoxB7 gene on DKK1, Wnt1, and β-catenin. Counting Kit-8, Transwell invasion assays, and flow cytometry were applied for the functional measurements.

RESULTS

The expression of HoxB7 was significantly increased, and of DKK1, Wnt1, and β-catenin was decreased, in FGR placenta tissues and in HTR-8/SVneo cells. Function studies revealed that overexpression of HoxB7 inhibited proliferation, migration, and invasion in HTR-8/SVneo cells. DKK1, Wnt1, and β-catenin were down-regulated in HTR-8/SVneo cells, inversely correlated with HoxB7 expression. Overexpression of HoxB7 showed a suppressive effect on proliferation, migration, and invasion in the HTR-8/SVneo cells.

CONCLUSIONS

Our results indicate that HoxB7 inhibited human trophoblast cell differentiation by down-regulating DKK1 expression and that it may affect transcription of Wnt1/β-catenin. The activation of HoxB7 might suppress the cell differentiation in HTR-8/SVneo cell cultures. The Wnt/β-catenin signaling pathway may play a significant role in the pathogenesis of FGR by regulating the invasion and proliferation of trophoblasts.

DNA Vectors Generating Engineered Exosomes Potential CTL Vaccine Candidates Against AIDS, Hepatitis B, and Tumors

Eukaryotic cells constitutively produce nanovesicles of 50-150 nm of diameter, referred to as exosomes, upon release of the contents of multivesicular bodies (MVBs). We recently characterized a novel, exosome-based way to induce cytotoxic T lymphocyte (CTL) immunization against full-length antigens. It is based on DNA vectors expressing products of fusion between the exosome-anchoring protein Nef mutant (Nef^mut) with the antigen of interest. The strong efficiency of Nef^mut to accumulate in MVBs results in the production of exosomes incorporating huge amounts of the desired antigen. When translated in animals, the injection of Nef^mut-based DNA vectors generates engineered exosomes whose internalization in antigen-presenting cells induces cross-priming and antigen-specific CTL immunity. Here, we describe the molecular strategies we followed to produce DNA vectors aimed at generating immunogenic exosomes potentially useful to elicit a CTL immune response against antigens expressed by the etiologic agents of major chronic viral infections, i.e., HIV-1, HBV, and the novel tumor-associated antigen HOXB7. Unique methods intended to counteract intrinsic RNA instability and nuclear localization of the antigens have been developed. The success we met with the production of these engineered exosomes opens the way towards pre-clinic experimentations devoted to the optimization of new vaccine candidates against major infectious and tumor pathologies.

Elucidating the gene regulatory networks modulating cancer stem cells and non-stem cancer cells in high grade serous ovarian cancer

The origin and pathogenesis of epithelial ovarian cancer have perplexed investigators for decades. The most prevalent type of it is the high-grade serous ovarian carcinoma (HGSOv) which is a highly aggressive disease with high relapse rates and insurgence of chemo-resistance at later stages of treatment. These are driven by a rare population of stem cell like cancer cells called cancer stem cells (CSCs). We have taken up a systems approach to find out the common gene interaction paths between non-CSC tumor cells (CCs) and CSCs in HGSOv. Detailed investigation reveals a set of 17 Transcription Factors (named as pivot-TFs) which can govern changes in the mode of gene regulation along these paths. Overall, this work highlights a divergent road map of functional information relayed by these common key players in the two cell states, which might aid towards designing novel therapeutic measures to target the CSCs for ovarian cancer therapy.

The transcription factor HOXB7 regulates ERK kinase activity and thereby stimulates the motility and invasiveness of pancreatic cancer cells

HOX genes encode transcription factors that function as sequence-specific transcription factors that are involved in cellular proliferation, differentiation, and death. The aim of this study was to investigate the role of a HOX family protein, HOXB7, in the motility and invasiveness of pancreatic cancer cells. We previously identified a HOXB7 transcript that is one of a number of transcripts that are preferentially translated in membrane protrusions in pancreatic cancer cells. Immunocytochemistry showed that HOXB7 was localized to the cell protrusions of migrating pancreatic cancer cells. Knockdown of HOXB7 by transfection with HOXB7-specific siRNA decreased these protrusions and inhibited the motility and invasiveness of the cells. Transfection of a HOXB7-rescue construct into the HOXB7-knockdown cells restored peripheral actin structures in cell protrusions and abrogated the HOXB7 knockdown-induced decrease in cell protrusions. It is generally accepted that the Rho family of GTPases regulate the organization of actin filaments and contribute to the formation of cell protrusions. The levels of the active Rho GTPases were not influenced by HOXB7 in the cells; however, HOXB7 knockdown decreased the level of phosphorylated ERK1/2. This inactivation of ERK1/2 decreased cell protrusions, thereby inhibiting the invasiveness of pancreatic cancer cells. Further investigation showed that HOXB7/ERK1/2 signaling selectively stimulated JNK and HSP27 phosphorylation and thereby increased the motility and invasiveness of pancreatic cancer cells. These results suggested that HOXB7 stimulates ERK1/2 phosphorylation and provided evidence that HOXB7, besides its role in transcriptional regulation, also promotes cell motility and invasiveness.

Systematic review: Tumor-associated antigen autoantibodies and ovarian cancer early detection

OBJECTIVES

Tumor-associated autoantibodies (AAbs), produced as an immune response to tumor-associated antigens (TAAs), are a novel pathway of early detection markers.

METHODS

We conducted a systematic review on AAbs and ovarian cancer to summarize the diagnostic performance of individual AAbs and AAb panels. A total of 29 studies including 85 AAbs were included; 27 of the studies were conducted in prevalent cases and cancer-free controls and 2 investigations included pre-diagnosis samples. The majority of studies were hypothesis-driven, evaluating AAbs to target TAAs; 10 studies used screening approaches such as serological expression cloning (SEREX) and nucleic acid-programmable protein arrays (NAPPA).

RESULTS

The highest sensitivities for individual AAbs were reported for RhoGDI-AAbs (89.5%) and TUBA1C-AAbs (89%); however, specificity levels were relatively low (80% and 75%, respectively). High sensitivities at high specificities were reported for HOXA7-AAbs for detection of moderately differentiated ovarian tumors (66.7% sensitivity at 100% specificity) and IL8-AAbs in stage I-II ovarian cancer (65.5% sensitivity at 98% specificity). A panel of 11 AAbs (ICAM3, CTAG2, p53, STYXL1, PVR, POMC, NUDT11, TRIM39, UHMK1, KSR1, and NXF3) provided 45% sensitivity at 98% specificity for serous ovarian cancer, when at least 2 AAbs were above a threshold of 95% specificity. Twelve of the AAbs identified in this review were investigated in more than one study. Data on diagnostic discrimination by tumor histology and stage at diagnosis are sparse. Limited data suggest select AAb markers improve diagnostic discrimination when combined with markers such as CA125 and HE4.

CONCLUSIONS

AAbs for ovarian cancer early detection is an emerging area, and large-scale, prospective investigations considering histology and stage are required for discovery and validation. However, data to date suggests panels of AAbs may eventually reach sufficient diagnostic discrimination to allow earlier detection of disease as a complement to existing markers and transvaginal ultrasound.

Enrichment of putative PAX8 target genes at serous epithelial ovarian cancer susceptibility loci

BACKGROUND

Genome-wide association studies (GWAS) have identified 18 loci associated with serous ovarian cancer (SOC) susceptibility but the biological mechanisms driving these findings remain poorly characterised. Germline cancer risk loci may be enriched for target genes of transcription factors (TFs) critical to somatic tumorigenesis.

METHODS

All 615 TF-target sets from the Molecular Signatures Database were evaluated using gene set enrichment analysis (GSEA) and three GWAS for SOC risk: discovery (2196 cases/4396 controls), replication (7035 cases/21 693 controls; independent from discovery), and combined (9627 cases/30 845 controls; including additional individuals).

RESULTS

The PAX8-target gene set was ranked 1/615 in the discovery (PGSEA<0.001; FDR=0.21), 7/615 in the replication (PGSEA=0.004; FDR=0.37), and 1/615 in the combined (PGSEA<0.001; FDR=0.21) studies. Adding other genes reported to interact with PAX8 in the literature to the PAX8-target set and applying an alternative to GSEA, interval enrichment, further confirmed this association (P=0.006). Fifteen of the 157 genes from this expanded PAX8 pathway were near eight loci associated with SOC risk at P<10-5 (including six with P<5 × 10-8). The pathway was also associated with differential gene expression after shRNA-mediated silencing of PAX8 in HeyA8 (PGSEA=0.025) and IGROV1 (PGSEA=0.004) SOC cells and several PAX8 targets near SOC risk loci demonstrated in vitro transcriptomic perturbation.

CONCLUSIONS

Putative PAX8 target genes are enriched for common SOC risk variants. This finding from our agnostic evaluation is of particular interest given that PAX8 is well-established as a specific marker for the cell of origin of SOC.

Overexpression of HOXB7 protein reduces sensitivity of oral cancer cells to chemo-radiotherapy

The upregulation of homeobox-B7 (HOXB7) in cancers has been reported. However, its role in oral cancer progression remains to be investigated. In current study, our data revealed that reconstitution of HOXB7 expression by transient transfection resulted in increased cell growth, migration and invasion in vitro. In addition, apoptosis and clonogenic assay data showed that overexpression of HOXB7 decreased the sensitivity of oral cancer cells to vincristine-induced apoptosis of HSC-4 and KB/VCR cells. Furthermore, overexpression of HOXB7 promoted oral cancer cells' migration and invasion through activation of TGFβ2/SMAD3 signaling pathway. Moreover, forced expression of HOXB7 increased Bcl-2 to Bax ratio, which would promote cell survival and induce drug and radiotherapy resistance. Altogether, our findings support the role of HOXB7 in the progression of oral cancer. Therefore, HOXB7 potentially can be a therapeutic target for oral cancer.

mRNA expression of CDH3, IGF2BP3, and BIRC5 in biliary brush cytology specimens is a useful adjunctive tool of cytology for the diagnosis of malignant biliary stricture

Although advances have been made in diagnostic tools, the distinction between malignant and benign biliary strictures still remains challenging. Intraductal brush cytology is a convenient and safe method that is used for the diagnosis of biliary stricture, but, low sensitivity limits its usefulness. This study aimed to demonstrate the usefulness of mRNA expression levels of target genes in brush cytology specimens combined with cytology for the diagnosis of malignant biliary stricture. Immunohistochemistry for cadherin 3 (CDH3), p53, insulin-like growth factor II mRNA-binding protein 3 (IGF2BP3), homeobox B7 (HOXB7), and baculoviral inhibitor of apoptosis repeat containing 5 (BIRC5) was performed in 4 benign and 4 malignant bile duct tissues. Through endoscopic or interventional radiologic procedures, brush cytology specimens were prospectively obtained in 21 and 35 paitents with biliary strictures. In the brush cytology specimens, the mRNA expressions levels of 5 genes were determined by real-time polymerase chain reaction. Immunohistochemistry for CDH3, p53, IGF2BP3, HOXB7, and BIRC5 all showed positive staining in malignant tissues in contrast to benign tissues, which were negative. In the brush cytology specimens, the mRNA expression levels of CDH3, IGF2BP3, HOXB7, and BIRC5 were significantly higher in cases of malignant biliary stricture compared with cases of benign stricture (P = 0.006, P < 0.001, P < 0.001, and P = 0.001). The receiver-operating characteristic curves of these 4 mRNAs demonstrated that mRNA expression levels are useful for the prediction of malignant biliary stricture (P = 0.006, P < 0.001, P < 0.001, and P = 0.002). The sensitivity and specificity, respectively, for malignant biliary stricture were 57.1% and 100% for cytology, 57.1% and 64.3% for CDH3, 76.2% and 100% for IGF2BP3, 71.4% and 57.1% for HOXB7, and 76.2% and 64.3% for BIRC5. When cytology was combined with the mRNA levels of CDH3, IGF2BP3, or BIRC5, the sensitivity for malignant biliary stricture improved to 90.5%. The measurement of the mRNA expression levels of CDH3, IGF2BP3, and BIRC5 by real-time polymerase chain reaction combined with cytology was useful for the differentiation of malignant and benign biliary strictures in brush cytology specimens.

Network-Based Integration of GWAS and Gene Expression Identifies a HOX-Centric Network Associated with Serous Ovarian Cancer Risk

BACKGROUND

Genome-wide association studies (GWAS) have so far reported 12 loci associated with serous epithelial ovarian cancer (EOC) risk. We hypothesized that some of these loci function through nearby transcription factor (TF) genes and that putative target genes of these TFs as identified by coexpression may also be enriched for additional EOC risk associations.

METHODS

We selected TF genes within 1 Mb of the top signal at the 12 genome-wide significant risk loci. Mutual information, a form of correlation, was used to build networks of genes strongly coexpressed with each selected TF gene in the unified microarray dataset of 489 serous EOC tumors from The Cancer Genome Atlas. Genes represented in this dataset were subsequently ranked using a gene-level test based on results for germline SNPs from a serous EOC GWAS meta-analysis (2,196 cases/4,396 controls).

RESULTS

Gene set enrichment analysis identified six networks centered on TF genes (HOXB2, HOXB5, HOXB6, HOXB7 at 17q21.32 and HOXD1, HOXD3 at 2q31) that were significantly enriched for genes from the risk-associated end of the ranked list (P < 0.05 and FDR < 0.05). These results were replicated (P < 0.05) using an independent association study (7,035 cases/21,693 controls). Genes underlying enrichment in the six networks were pooled into a combined network.

CONCLUSION

We identified a HOX-centric network associated with serous EOC risk containing several genes with known or emerging roles in serous EOC development.

IMPACT

Network analysis integrating large, context-specific datasets has the potential to offer mechanistic insights into cancer susceptibility and prioritize genes for experimental characterization.

HOXB7-S3 inhibits the proliferation and invasion of MCF-7 human breast cancer cells

Homeobox B7 (HOXB7) has been found to be overexpressed in numerous types of human cancer. However, the role of HOXB7 in breast cancer remains to be elucidated. The aim of the present study was to investigate the effects of HOXB7 on the proliferation and invasion of breast cancer cells. Initially, reverse transcription quantitative polymerase chain reaction and western blotting were respectively employed to detect the mRNA and protein expression levels of the HOXB7 gene in the MDA-MB-231 and MCF-7 human breast cancer cell lines. Subsequently, small interfering RNAs designed to interfere with the expression of HOXB7 were used to knockdown the expression of HOXB7 in the MCF-7 cell line, the effects of which on cell proliferation, the apoptotic rate and invasion capacity were measured using a Cell Counting kit-8 assay, flow cytometry and transwell chambers, respectively. The results demonstrated that HOXB7 mRNA and protein were all overexpressed in MDA-MB-231 and MCF-7 breast cancer cell lines. Furthermore, HOXB7-S3 effectively inhibited the proliferation and invasion of MCF-7 breast cancer cells. In conclusion, these results demonstrated that HOXB7 may be a potential therapeutic target in human breast cancer.

Deregulated HOXB7 Expression Predicts Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma and Regulates Cancer Cell Proliferation In Vitro and In Vivo

Background

We observed abnormal HOXB7 expression in esophageal squamous cell carcinoma (ESCC) previously. This study was to evaluate the prognostic significance of HOXB7 and reveal the potential mechanism.

Methods

Immunohistochemistry was used to confirm the abnormal expression of HOXB7 in ESCC. The prognostic significance of HOXB7 expression was analyzed in two independent cohorts. RNAi was used to establish two stable HOXB7-knockdown cell strains. CCK8 assay, cell growth curve assay, colony formation assay, flow cycle analysis and tumorigenicity assay in nude mice were employed to investigate the effect of HOXB7 on proliferation in vitro and in vivo.

Results

Immunohistochemistry confirmed the abnormal expression of HOXB7 in ESCC compared with paracancerous mucosa (18/23 vs. 9/23, p=0.039). HOXB7 expression was positively correlated with the T stage, lymph node metastasis and TNM stage. The median survival of patients with high HOXB7 expression was significantly shorter than that with low expression (45 months vs. 137 months, p = 0.007 for cohort 1; 19 months vs. 34 months, p = 0.001 for cohort 2). Multivariate survival analysis showed that HOXB7 expression was another independent prognostic factor (HR [95% CI] = 0.573 [0.341–0.963], p = 0.036 for cohort 1; HR [95%CI] = 0.543 [0.350–0.844], p = 0.024 for cohort 2). Experiments in vitro and in vivo showed that after knockdown of HOXB7, the proliferation rate dropped, growth rate descended, colony-formation ability reduced, G1-phase arrest occurred and the tumorigenicity reduced remarkably.

Conclusions

HOXB7 could promote cancer cell proliferation and might be an independent prognostic factor for patients with ESCC.

HOXA10 controls proliferation, migration and invasion in oral squamous cell carcinoma

Although HOX genes are best known for acting in the regulation of important events during embryogenesis, including proliferation, differentiation and migration, alterations in their expression patterns have been frequently described in cancers. In previous studies we analyzed the expression profile of the members of the HOX family of homeobox genes in oral samples of normal mucosa and squamous cell carcinoma (OSCC) and identified differently expressed genes such as HOXA10. The present study aimed to validate the increased expression of HOXA10 in OSCCs, and to investigate the effects arising from its knockdown in OSCC cells. The levels of HOXA10 mRNA were determined in human OSCC samples and cell lines by quantitative PCR, and HOXA10-mediated effects on proliferation, apoptosis, adhesion, epithelial-mesenchymal transition (EMT), migration and invasion were studied in HSC-3 tongue carcinoma cells by using retrovirus-mediated RNA interference. Higher expression of HOXA10 mRNA was observed in OSCC cell lines and in tumor tissues compared to normal controls. HOXA10 knockdown significantly reduced the proliferation of the tumor cells which was accompanied by increased levels of p21. HOXA10 silencing also significantly induced the expression of EMT markers and enhanced the adhesion, migration and invasion of HSC-3 cells. No effects on cell death were observed after HOXA10 knockdown. The results of the current study confirm the overexpression of HOXA10 in OSCCs, and further demonstrate that its expression is functionally associated with several important biological processes related to oral tumorigenesis, such as proliferation, migration and invasion.

Transcriptional dynamics of homeobox C11 gene in water buffalo bubalus bubalis

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

RNA interference of Biot2 induces G1 phase arrest and apoptosis in mouse colorectal cancer cell line

Biot2 is a tumor-associated antigen, and it is a novel gene (GenBank EF100607) that was first identified with the SEREX technique and named by our laboratory. It is highly expressed in cancer cells and testis, with low or no expression in normal tissues. In our previous study, RNA interference of human Biot2 can inhibit tumor cell growth, and it is associated with poor prognosis of patients in clinical study; however, the mechanism of Biot2 that effects tumor growth is not yet clear. Here, in this study, we explore further the mechanism of Biot2 by silencing Biot2 in CT26 cells. It provides some theoretical basis for Biot2 as a new target for gene therapy. In CT26 cells, the expression of Biot2 was downregulated by Biot2-shRNA. It also promoted G₁ phase arrest, the expression of p16 and p21, and cell apoptosis. In the mouse model, the tumor volume and the expression of PCNA of the Biot2-shRNA group significantly decreased. These results suggest that silencing Biot2 in CT26 cells by RNA interference can inhibit cell growth in vitro and in vivo. It also induces cell cycle arrest in the G₁ phase and apoptosis throughout regulation of p16 and p21. Taken together, our data demonstrate that Biot2 can be a potential target of gene therapy.

HOXB7 promotes malignant progression by activating the TGFβ signaling pathway

Overexpression of HOXB7 in breast cancer cells induces an epithelial-mesenchymal transition and promotes tumor progression and lung metastasis. However, the underlying mechanisms for HOXB7-induced aggressive phenotypes in breast cancer remain largely unknown. Here, we report that phosphorylation of SMAD3 was detected in a higher percentage in primary mammary tumor tissues from double-transgenic MMTV-Hoxb7/Her2 mice than tumors from single-transgenic Her2/neu mice, suggesting activation of TGFβ/SMAD3 signaling by HOXB7 in breast tumor tissues. As predicted, TGFβ2 was high in four MMTV-Hoxb7/Her2 transgenic mouse tumor cell lines and two breast cancer cell lines transfected with HOXB7, whereas TGFβ2 was low in HOXB7-depleted cells. HOXB7 directly bound to and activated the TGFβ2 promoter in luciferase and chromatin immunoprecipitation assays. Increased migration and invasion as a result of HOXB7 overexpression in breast cancer cells were reversed by knockdown of TGFβ2 or pharmacologic inhibition of TGFβ signaling. Furthermore, knockdown of TGFβ2 in HOXB7-overexpressing MDA-MB-231 breast cancer cells dramatically inhibited metastasis to the lung. Interestingly, HOXB7 overexpression also induced tumor-associated macrophage (TAM) recruitment and acquisition of an M2 tumor-promoting phenotype. TGFβ2 mediated HOXB7-induced activation of macrophages, suggesting that TAMs may contribute to HOXB7-promoted tumor metastasis. Providing clinical relevance to these findings, by real-time PCR analysis, there was a strong correlation between HOXB7 and TGFβ2 expression in primary breast carcinomas. Taken together, our results suggest that HOXB7 promotes tumor progression in a cell-autonomous and non-cell-autonomous manner through activation of the TGFβ signaling pathway.

HOXA7 stimulates human hepatocellular carcinoma proliferation through cyclin E1/CDK2

HOX genes are transcription factors that control morphogenesis, organogenesis and differentiation. Increasing evidence suggests that HOX genes play a role in hepatocellular carcinoma (HCC) progression; however few studies have defined the functional roles and mechanisms of action. In the present study, we used siRNA and forced-expression in multiple cell lines to define the role of HOXA7 in the regulation of proliferation of HCC in vitro and in vivo. Knockdown of endogenous HOXA7 decreased the proliferation of HepG2 and QGY-7703 cells. These changes were not associated with significant changes in cyclin D1 and CDK4. However, downregulation of HOXA7 significantly reduced cyclin E1 and CDK2 protein levels. Conversely, overexpression of HOXA7 in QSG-7701 cells stimulated proliferation and increased cyclin E1 and CDK2 protein levels. Our results confirmed that HOXA7 promoted cell proliferation, and these changes were mediated by cyclin E1/CDK2. These observations contribute to our understanding of the important roles of HOXA7 in HCC development and progression and HOXA7 could be a promising molecular target for the development of new diagnostic and therapeutic strategies for HCC.

Homeobox Gene Deregulation: Impact on the Hallmarks of Cancer

Homeobox genes comprise a super-family of evolutionarily conserved genes that play essential roles in controlling body plan specification and cell fate determination. Substantial evidence indicates that leukemogenesis is driven by abnormal expression of homeobox genes that control hematopoiesis. In solid tumors, aberrant expression of homeobox genes has been increasingly found to modulate diverse processes such as cell proliferation, cell death, metastasis, angiogenesis and DNA repair. This review discusses how homeobox genes are deregulated in solid tumors and the functional significance of this deregulation in the hallmarks of cancer.

Prognostic value of HOXB7 mRNA expression in human oesophageal squamous cell cancer

OBJECTIVE

This study was to determine the role of HOXB7 in predicting outcomes of patients with oesophageal squamous cell cancer (OSCC).

METHODS

Samples were collected from 179 OSCC patients. HOXB7 mRNA expression was measured by quantitative real-time polymerase chain reaction.

RESULTS

HOXB7 mRNA expression was up-regulated in 85.1% of OSCC tumorous tissues, and correlated with age, pathological T and N category, as well as cancer-specific survival (CSS). However, subgroup analysis revealed its discernibility on CSS was only pronounced in early stage.

CONCLUSIONS

HOXB7 mRNA expression might serve as a novel prognostic biomarker for resected OSCC patients in early stage.

HOXB8 expression in ovarian serous carcinoma effusions is associated with shorter survival

OBJECTIVE

HOX proteins are key transcription factors in embryogenesis. HOXB5 and HOXB8 were previously shown to be overexpressed in ovarian/primary peritoneal serous carcinoma compared to breast carcinoma using gene expression arrays. The present study investigated the clinical role of HOXB5 and HOXB8 in advanced-stage (FIGO III-IV) ovarian serous carcinoma.

METHODS

HOXB5 and HOXB8 protein expression was analyzed in 286 effusions and 76 patient-matched solid lesions (27 primary carcinomas, 49 metastases) using immunohistochemistry. Expression was analyzed for association with clinicopathologic parameters, including survival.

RESULTS

Cytoplasmic HOXB5 protein was detected in 268/286 (94%) effusions. HOXB8 was expressed at both the cytoplasm (252/286; 88%) and nucleus (131/286; 46%) of carcinoma cells. Cytoplasmic HOXB5, cytoplasmic HOXB8 and nuclear HOXB8 were found in 56/76 (74%), 76/76 (100%) and 30/76 (39%) solid lesions, respectively, with significantly higher HOXB5 expression in effusions (p=0.002) and higher cytoplasmic HOXB8 in solid lesions (p<0.001). HOXB5 expression was higher in post-chemotherapy disease recurrence effusions compared to pre-chemotherapy effusions tapped at diagnosis (p=0.04). In univariate survival analysis of the effusion cohort, higher expression of cytoplasmic HOXB8 was associated with significantly shorter progression-free survival (p=0.033), whereas higher nuclear HOXB8 expression was associated with significantly shorter overall survival in analysis limited to patients with post-chemotherapy effusions (p=0.036). Neither finding was independent prognostic factor in Cox multivariate analysis.

CONCLUSIONS

HOXB5 and HOXB8 are frequently expressed in ovarian serous carcinoma, with anatomic site-related differences for cytoplasmic staining. HOXB5 may be affected by chemotherapy in effusions. HOXB8 expression is associated with shorter survival in metastatic serous carcinoma.

HOXB7 promotes invasion and predicts survival in pancreatic adenocarcinoma

BACKGROUND

The homeobox gene HOXB7 is overexpressed across a range of cancers and promotes tumorigenesis through varying effects on proliferation, survival, invasion, and angiogenesis. Although published microarray data suggest HOXB7 is overexpressed in pancreatic ductal adenocarcinoma (PDAC), its function in pancreatic cancer has not been studied.

METHODS

HOXB7 message and protein levels were examined in PDAC cell lines and patient samples, as well as in normal pancreas. HOXB7 protein expression in patient tumors was determined by immunohistochemistry and correlated with clinicopathologic factors and survival. The impact of HOXB7 on cell proliferation, growth, and invasion was assessed by knockdown and overexpression in PDAC cell lines. Candidate genes whose expression levels were altered following HOXB7 knockdown were determined by microarray analysis.

RESULTS

HOXB7 message and protein levels were significantly elevated in PDAC cell lines and patient tumor samples relative to normal pancreas. Evaluation of a tissue microarray of 145 resected PDACs found high HOXB7 protein expression was correlated with lymph node metastasis (P = .034) and an independent predictor of worse overall survival in multivariate analysis (hazard ratio = 1.56, 95% confidence interval = 1.02-2.39). HOXB7 knockdown or overexpression in PDAC cell lines resulted in decreased or increased invasion, respectively, without influencing proliferation or cell viability.

CONCLUSIONS

HOXB7 is frequently overexpressed in PDAC, specifically promotes invasive phenotype, and is associated with lymph node metastasis and worse survival outcome. HOXB7 and its downstream targets may represent novel clinical biomarkers or targets of therapy for inhibiting the invasive and metastatic capacity of PDAC.

Autoantibodies as biomarkers for ovarian cancer

Ovarian cancer (OVCA) has the highest mortality of all gynecologic cancers. The poor survival rate is due to the lack of diagnostic screening tests and high incidence of recurrence in OVCA patients resistant to chemotherapy that leads to a more aggressive form of the disease. Therefore, a search for biomarkers holds great promise not only for early detection of OVCA at presymptomatic stage and for monitoring the course of the disease during the first-line chemotherapy treatment but also for identifying those women whose disease is likely to recur. Research efforts have sought to unravel the complexity of the tumor specific proteome by profiling immune responses generated against tumor associated antigens (TAAs) using multianalyte-based analytical discovery platforms readily adaptable to clinical diagnostic screening tests. The occurrence of tumor-specific autoantibodies directed to respective TAAs can be observed before the development of clinical symptoms. Evaluation of the level of tumor autoantibodies during the time of tumor debulking followed by first-line chemotherapy for the prediction of early recurrence as well as their correlation with other clinical parameters to evaluate their prognostic value has been conducted in various clinical studies. The anti-tumor immune response against OVCA is the ultimate key to the development of multiple immune-based therapeutic strategies that have been proposed and tested in different clinical trials that may have beneficial impact on the disease outcome in OVCA patients.

Expression level of pre-B-cell leukemia transcription factor 2 (PBX2) as a prognostic marker for gingival squamous cell carcinoma

OBJECTIVE

In this study, we investigated the interrelationship between clinicopathologic findings and pre-B-cell leukemia transcription factor 2 (PBX2) expression in gingival squamous cell carcinoma (GSCC).

METHODS

Expression level of PBX2 was immunohistochemically examined in 66 GSCC subjects (30 men and 36 women) with ages ranging from 42 to 85 (median 64.5) years, in which staining intensity in tumor cells was categorized as either weaker (level 1) or equal to/stronger (level 2) than that in the endothelial cells.

RESULTS

PBX2 expression is correlated with valosin-containing protein (VCP) expression. Univariate and multivariate analyses revealed a high level of PBX2 expression to be a poor prognosticator for disease-free survival (DFS) and overall survival (OS), and PBX2 expression was an independent prognostic factor for both DFS and OS in GSCC.

CONCLUSIONS

PBX2 expression level in GSCC is prognostic. PBX2 may be a useful marker to identify the potential for progression in GSCC.

A novel cancer/testis antigen KP-OVA-52 identified by SEREX in human ovarian cancer is regulated by DNA methylation

SEREX has proven to be a powerful method that takes advantage of the presence of spontaneous humoral immune response in some cancer patients. In this study, immunoscreening of normal testis and two ovarian cancer cell line cDNA expression libraries with sera from ovarian cancer patients led to the isolation of 75 independent antigens, designated KP-OVA-1 through KP-OVA-75. Of these, RT-PCR showed KP-OVA-52 to be expressed strongly in normal testis, in ovarian cancer cell lines (3/9) and in ovarian cancer tissues (1/17). The expression of KP-OVA-52 in cancer cells is also induced by the demethylating agent 5-aza-2′-deoxycytidine (ADC). To test immunogenicity, we used the Serum Antibody Detection Assay (SADA) to analyze anti-IgG antibodies against the 75 antigens that were initially isolated by SEREX. Four of the 75 antigens (KP-OVA-25, KP-OVA-35, KP-OVA-68 and KP-OVA-73) reacted exclusively with sera from cancer patients. However, KP-OVA-52 reacted with 1 of 20 ovarian cancer sera. These data suggest that the KP-OVA-52 can be considered a novel CT antigen that is regulated by DNA methylation.

Downregulation of alpha-fetoprotein expression by LHX4: a critical role in hepatocarcinogenesis

LHX4 is a member of the LIM-homeobox family and plays a critical role in pituitary development and differentiation. Several lines of evidences have reported their aberrant expression in cancers. However, the exact roles of LHX4 in carcinogenesis remain unclear. In this study, LHX4 expression was analyzed in tumor and paired non-tumor tissues obtained from patients with hepatocellular carcinoma (HCC) using western blotting and immunohistochemistry. LHX4 was found to be downregulated in tumor tissues and negatively correlated with differentiation grade and alpha-fetoprotein (AFP) levels in 66 HCC patients. To clarify the biological functions of LHX4, transient or stable transfectants overexpressing LHX4 were generated in human hepatoma cells (Huh7 and HepG2). LHX4 overexpression in Huh7 and HepG2 cells induced a more differentiated phenotype by reducing AFP expression. Using in silico analysis, the evolutionary conserved region within the AFP promoter containing LHX4-binding site was identified, implying that AFP is a putative target for LHX4. Moreover, ectopic LHX4 overexpression attenuated Huh7 and HepG2 proliferation. Importantly, the growth-inhibitory effect of LHX4 was reversed by replenishing AFP to the LHX4-overexpressing cells, providing a functional relevance between LHX4 and AFP. Finally, we analyzed expressions of LHX4 and AFP during normal liver development. Hepatic LHX4 expression increased in adult liver in a manner that parallel AFP repression. In conclusion, these data indicate that LHX4 may act as a potential tumor suppressor in hepatocarcinogenesis, suggesting that targeting LHX4 to downregulate AFP might have therapeutic implications.

The relationship among PDX1, CDX2, and mucin profiles in gastric carcinomas; correlations with clinicopathologic parameters

PURPOSE

Several studies performed on pancreatic-duodenal homeobox 1 (PDX1) have demonstrated a loss of expression and negative tumor modulator effect in gastric carcinoma. Relations between PDX1 and gastric metaplasia, differentiated type of gastric carcinoma, and the early stage of the disease have been exhibited in previous reports. The aim of this study was to examine expressions of PDX1, caudal type homeobox 2 (CDX2) and mucin (MUC) profiles to address the role of PDX1 in gastric carcinogenesis and its relationship with CDX2.

METHODS

Seventy gastrectomy specimens were analyzed immunohistochemically for PDX1, CDX2, MUC2, MUC5AC, and MUC6 expressions. The sum of cytoplasmic and nuclear PDX1 immunostaining and PDX1 positivity were assessed. All of the antibodies were examined for a correlation with tumor type, clinicopathologic parameters, and metaplasias. The relation of Ki-67 proliferation index with the expression profiles was also investigated.

RESULTS

Neither PDX1 (66/70) nor CDX2 (37/70) and the mucin profiles (MUC2:11/70, MUC5AC:48/70, MUC6:41/70) showed a significant difference between differentiated and undifferentiated types of gastric carcinoma and clinicopathologic parameters. The PDX1 expression frequency was 94.3%, with an average PDX1 score of 8.8 ± 4.2. PDX1 and CDX2 expression showed a significant difference (P = 0.026 and P = 0.002, respectively) among the phenotypic classification of gastric carcinomas. All of the gastric and intestinal mixed-phenotype gastric carcinomas (GI-type) showed both PDX1 and CDX2 immunopositivity. Except for the relation of PDX1 score with MUC6 expression, no significant difference was detected between PDX1 and CDX2, MUC2, and MUC5AC expressions. A relationship between CDX2 and MUC2 and also between MUC5AC and MUC6 was found statistically. The Ki-67 proliferation index revealed a significant positive correlation with PDX1, CDX2, and MUC2 positivity.

CONCLUSIONS

PDX1 expression revealed a higher positivity in gastric carcinomas than the previous studies and showed no relation with tumor type, clinicopathologic parameters, CDX2 expression, or mucin profiles. However, a significant relation of PDX1 and CDX2 expressions among phenotypic classification of gastric carcinomas reveals an idea about similar functions for PDX1 and CDX2 in the evolution of gastric carcinoma.

HOX genes in ovarian cancer

The HOX genes are a family of homeodomain-containing transcription factors that determine cellular identity during development. Here we review a number of recent studies showing that HOX genes are strongly expressed in ovarian cancer, and that in some cases the expression of specific HOX genes is sufficient to confer a particular identity and phenotype upon cancer cells. We also review the recent advances in elucidating the different functions of HOX genes in ovarian cancer. A literature search was performed using the search terms HOX genes (including specific HOX genes), ovarian cancer and oncogenesis. Articles were accessed through searches performed in ISI Web of Knowledge, PubMed and ScienceDirect. Taken together, these studies have shown that HOX genes play a role in the oncogenesis of ovarian cancer and function in the inhibition of apoptosis, DNA repair and enhanced cell motility. The function of HOX genes in ovarian cancer oncogenesis supports their potential role as prognostic and diagnostic markers, and as therapeutic targets in this disease.

HOXB7 as a prognostic factor and mediator of colorectal cancer progression

PURPOSE

This study was to investigate the clinicopathologic significance and potential role of HOXB7 in the development and progression of colorectal cancer (CRC).

EXPERIMENTAL DESIGN

The relationship between HOXB7 expression and clinical characteristics of CRC was analyzed in 224 paraffin-embedded archived CRC specimens by immunohistochemistry (IHC). The effects of HOXB7 on cell growth and proliferation, as well as on tumorigenesis, were examined both in vitro and in vivo, using MTT assay, colony formation assay, cell cycle analysis, soft agar assay, and tumorigenesis in nude mice. Western blotting and real-time reverse transcriptase-PCR were performed to examine the impact of HOXB7 on the PI3K/Akt and MAPK signaling pathways.

RESULTS

HOXB7 protein level was significantly correlated with advanced Dukes stage (P < 0.001), T stage (P = 0.012), distant metastasis (P = 0.042), higher proliferation index (P = 0.007) and poor survival of patients (P = 0.005). Enforced expression of HOXB7 in CRC cell lines significantly enhanced cell growth, proliferation and tumorigenesis. Conversely, knockdown of HOXB7 caused an inhibition of cell growth, proliferation, and tumorigenesis. We also showed that HOXB7 accelerated G(0)-G(1) to S-phase transition concomitantly with upregulation of cyclin D1 and downregulation of p27Kip1. On the contrary, knockdown of HOXB7 caused G(1)-S-phase arrest, downregulation of cyclin D1 and upregulation of p27Kip1. Enforced expression of HOXB7 could enhance PI3K/AKT and MAPK pathway activity.

CONCLUSION

Our findings suggest that HOXB7 protein, as a valuable marker of CRC prognosis, plays an important role in the development and progression of human CRC.

Homeodomain protein DLX4 counteracts key transcriptional control mechanisms of the TGF-β cytostatic program and blocks the antiproliferative effect of TGF-β

The antiproliferative activity of transforming growth factor-β (TGF-β) is essential for maintaining normal tissue homeostasis and is lost in many types of tumors. Gene responses that are central to the TGF-β cytostatic program include activation of the cyclin-dependent kinase inhibitors, p15(Ink4B) and p21(WAF1/Cip1), and repression of c-myc. These gene responses are tightly regulated by a repertoire of transcription factors that include Smad proteins and Sp1. The DLX4 homeobox patterning gene encodes a transcription factor that is absent from most normal adult tissues, but is expressed in a wide variety of malignancies, including lung, breast, prostate and ovarian cancers. In this study, we demonstrate that DLX4 blocks the antiproliferative effect of TGF-β. DLX4 inhibited TGF-β-mediated induction of p15(Ink4B) and p21(WAF1/Cip1) expression. DLX4 bound and prevented Smad4 from forming complexes with Smad2 and Smad3, but not with Sp1. However, DLX4 also bound and inhibited DNA-binding activity of Sp1. In addition, DLX4 induced expression of c-myc independently of TGF-β/Smad signaling. The ability of DLX4 to counteract key transcriptional control mechanisms of the TGF-β cytostatic program could explain, in part, the resistance of tumors to the antiproliferative effect of TGF-β.

Upregulation of DLX5 promotes ovarian cancer cell proliferation by enhancing IRS-2-AKT signaling

The distal-less homeobox gene (dlx) 5 encodes a transcription factor that controls jaw formation and appendage differentiation during embryonic development. We had previously found that Dlx5 is overexpressed in an Akt2 transgenic model of T-cell lymphoma. To investigate if DLX5 is involved in human cancer, we screened its expression in the NCI 60 cancer cell line panel. DLX5 was frequently upregulated in cell lines derived from several tumor types, including ovarian cancer. We next validated its upregulation in primary ovarian cancer specimens. Stable knockdown of DLX5 by lentivirus-mediated transduction of short hairpin RNA (shRNA) resulted in reduced proliferation of ovarian cancer cells due to inhibition of cell cycle progression in connection with the downregulation of cyclins A, B1, D1, D2, and E, and decreased phosphorylation of AKT. Cell proliferation resumed following introduction of a DLX5 cDNA harboring wobbled mutations at the shRNA-targeting sites. Cell proliferation was also rescued by transduction of a constitutively active form of AKT. Intriguingly, downregulation of IRS-2 and MET contributed to the suppression of AKT signaling. Moreover, DLX5 was found to directly bind to the IRS-2 promoter and augmented its transcription. Knockdown of DLX5 in xenografts of human ovarian cancer cells resulted in markedly diminished tumor size. In addition, DLX5 was found to cooperate with HRAS in the transformation of human ovarian surface epithelial cells. Together, these data suggest that DLX5 plays a significant role in the pathogenesis of some ovarian cancers.

Peptide mimic isolated by autoantibody reveals human arrest defective 1 overexpression is associated with poor prognosis for colon cancer patients

Tumor-associated antigens, which induce the generation of autoantibodies, are useful as cancer biomarkers in early detection and prognostic prediction of cancer. To isolate a novel cancer marker, we used serum antibodies from colon cancer patients to screen a phage display peptide library. A positive peptide 249C (VPLYSNTLRYGF) that could specifically react with serum from colon cancer patients was isolated, and the corresponding antigen-human arrest defective 1 (ARD1A), which shares an identical LYSNTL motif with 249C, was identified. Both immunological assays and three-dimensional structure analysis showed that the LYSNTL region is an epitope of ARD1A. Using ELISA and immunohistochemistry, we found anti-ARD1A antibody levels in serum from patients with colon cancer were significantly higher than those in healthy volunteers (P < 0.001), and ARD1A expression was detected in 84.1% (227/270) of colon cancer tissues compared with 22.7% (55/242) of matched noncancerous tissues (P < 0.001) and 4.8% (2/42) of benign lesions (P < 0.001). Furthermore, multivariate analysis with Cox proportional hazards regression models revealed that ARD1A-positive patients had significantly shortened overall survival (OS) (HR, 1.91, P = 0.039) and borderline significantly shortened disease-free survival (DFS) (HR, 1.70; P = 0.068). Kaplan-Meier survival curves also showed that ARD1A expression was associated significantly with shortened DFS (P = 0.037) and OS (P = 0.019). These results indicate that ARD1A is a novel tumor-associated antigen and a potential prognostic factor for colon cancer.

Analysis of the expression of human tumor antigens in ovarian cancer tissues

Biomarkers for early detection of cancer have great clinical diagnostic potential. Numerous reports have documented the generation of humoral immune responses that are triggered in response to changes in protein expression patterns in tumor tissues and these biomarkers are referred to as tumor associated antigens (TAAs). Using a high-throughput technology, we previously identified 65 proteins as diagnostically useful TAAs by profiling the humoral immune responses in ovarian cancer (OVCA) patients. Here we determined the expression status of some of those TAAs in tissues from OVCA patients. The protein expression patterns of 4 of those 65 antigens, namely NASP, RCAS1, Nijmegen breakage syndrome1 (NBS1) and eIF5A, along with p53 and Her2 (known molecular prognosticators) and two proteins that interact with NBS1, MRE11 and RAD50, were assessed by immunohistochemistry (IHC). NASP and RCAS1 proteins were more frequently expressed in ovarian cancer tissues than with normal ovarian tissue and serous cystadenomas and MRE11 was less frequently expressed. When evaluated simultaneously, only NASP and MRE11 remained statistically significant with sensitivity of 66% and specificity of 89%. None of these proteins' expression levels were prognostic for survival. Together, our results indicate that occurrence of humoral immune responses against some of these TAAs in OVCA patients is triggered by antigen protein overexpression.

Expression pattern of the class I homeobox genes in ovarian carcinoma

OBJECTIVE

Although some sporadic reports reveal the link between the homeobox (HOX) genes and ovarian carcinoma, there is no comprehensive analysis of the expression pattern of the class I homeobox genes in ovarian carcinoma that determines the candidate genes involved in ovarian carcinogenesis.

METHODS

The different patterns of expression of 36 HOX genes were analyzed, including 4 ovarian cancer cell lines and 4 normal ovarian tissues. Using a reverse transcription-polymerase chain reaction (RT-PCR) and quantification analysis, the specific gene that showed a significantly higher expression in ovarian cancer cell lines than in normal ovaries was selected, and western blot analysis was performed adding 7 ovarian cancer tissue specimens. Finally, immunohistochemical and immunocytochemical analyses were performed to compare the pattern of expression of the specific HOX gene between ovarian cancer tissue and normal ovaries.

RESULTS

Among 36 genes, 11 genes had a different level of mRNA expression between the cancer cell lines and the normal ovarian tissues. Of the 11 genes, only HOXB4 had a significantly higher level of expression in ovarian cancer cell lines than in normal ovaries (p=0.029). Based on western blot, immunohistochemical, and immunocytochemical analyses, HOXB4 was expressed exclusively in the ovarian cancer cell lines or cancer tissue specimens, but not in the normal ovaries.

CONCLUSION

We suggest HOXB4 may be a novel candidate gene involved in ovarian carcinogenesis.

Autoantibodies to tumor-associated antigens in epithelial ovarian carcinoma

This review will focus on recent knowledge related to circulating autoantibodies (AAbs) to tumor-associated antigens (TAAs) in epithelial ovarian carcinoma. So far, the following TAAs have been identified to elicit circulating AAbs in epithelial ovarian carcinoma: p53, homeobox proteins (HOXA7, HOXB7), heat shock proteins (HSP-27, HSP-90), cathepsin D, cancer-testis antigens (NY-ESO-1/LAGE-1), MUC1, GIPC-1, IL-8, Ep-CAM, and S100A7. Since AAbs to TAAs have been identified in the circulation of patients with early-stage cancer, it has been speculated that the assessment of a panel of AAbs specific for epithelial ovarian carcinoma TAAs might hold great potential as a novel tool for early diagnosis of epithelial ovarian carcinoma.

Genomic and proteomic biomarkers for cancer: a multitude of opportunities

Biomarkers are molecular indicators of a biological status, and as biochemical species can be assayed to evaluate the presence of cancer and therapeutic interventions. Through a variety of mechanisms cancer cells provide the biomarker material for their own detection. Biomarkers may be detectable in the blood, other body fluids, or tissues. The expectation is that the level of an informative biomarker is related to the specific type of disease present in the body. Biomarkers have potential both as diagnostic indicators and monitors of the effectiveness of clinical interventions. Biomarkers are also able to stratify cancer patients to the most appropriate treatment. Effective biomarkers for the early detection of cancer should provide a patient with a better outcome which in turn will translate into more efficient delivery of healthcare. Technologies for the early detection of cancer have resulted in reductions in disease-associated mortalities from cancers that are otherwise deadly if allowed to progress. Such screening technologies have proven that early detection will decrease the morbidity and mortality from cancer. An emerging theme in biomarker research is the expectation that panels of biomarker analytes rather than single markers will be needed to have sufficient sensitivity and specificity for the presymptomatic detection of cancer. Biomarkers may provide prognostic information of disease enabling interventions using targeted therapeutic agents as well as course-corrections in cancer treatment. Novel genomic, proteomic and metabolomic technologies are being used to discover and validate tumor biomarkers individually and in panels.

Sperm-associated antigen 9: a novel diagnostic marker for thyroid cancer

CONTEXT

Cancer-testis antigens are the unique class of testis proteins expressed in tumor but not healthy tissue except testis and might represent ideal targets for the development of novel diagnostics and therapeutic methods in thyroid cancer, which is the most common malignancy of the endocrine system.

OBJECTIVE

Our objective was to investigate the clinical relevance of cancer-testis antigen sperm-associated antigen 9 (SPAG9) as early diagnostic and therapeutic target in thyroid cancer.

DESIGN, SETTING, AND SUBJECTS

SPAG9 gene and protein expression was determined in thyroid cancer cell lines in 138 thyroid tumor specimens, 60 adjacent noncancerous tissues (ANCT), 22 multinodular goiters (nonneoplastic hyperplasia), and 20 follicular adenoma tissue samples by RT-PCR, in situ RNA hybridization, and immunohistochemistry. Gene silencing approach was used to examine the effects of suppression of SPAG9 protein on cellular growth and colony formation. Humoral immune response against SPAG9 in thyroid cancer patients was analyzed using ELISA.

RESULTS

SPAG9 mRNA and protein expression was detected in 78% of the thyroid cancer patients but not multiple goiters and follicular adenoma disease patients. It is interesting to note that majority of early-stage (T1) thyroid cancer patients exhibited higher antibody response against SPAG9. Small interfering RNA-mediated knockdown of SPAG9 expression in thyroid cancer cell significantly reduced cellular growth and colony formation.

CONCLUSIONS

SPAG9 expression may play a role in cellular growth and thyroid carcinogenesis. These findings support a potential role for SPAG9 as diagnostic biomarker as well as a possible therapeutic target in thyroid cancer treatment.

Patient-derived tumor-reactive antibodies as diagnostic markers for ovarian cancer

OBJECTIVE

Most ovarian cancers are diagnosed at advanced stage (67%) and prospects for significant improvement in survival reside in early diagnosis. Our objective was to validate our array assay for the identification of ovarian cancer based on quantitation of tumor-reactive IgG.

METHODS

The diagnostic array utilizes specific exosome-derived antigens to detect reactive IgG in patients' sera. Specific protein targets were isolated by immunoaffinity from exosomes derived from ovarian tumor cell lines. Sera were obtained from age-matched female volunteers, women with benign ovarian disease and with ovarian cancer. Immunoreactivity was also compared between exosomal proteins and their recombinant counterparts.

RESULTS

Sera from ovarian cancer patients exhibited significantly greater immunoreactivities than either normal controls or women with benign disease (both considered negative to all antigens tested). Reactivities with nucleophosmin, cathepsin D, p53, and SSX common antigen for patients with all stages of ovarian cancer were significantly higher than for controls and women with benign ovarian disease. Reactivity with placental type alkaline phosphatase, TAG 72, survivin, NY-ESO-1, GRP78, and Muc16 (CA125) allowed the differentiation between Stage III/IV and early stage ovarian cancer.

CONCLUSIONS

The quantitation of circulating tumor-reactive IgG can be used to identify the presence of ovarian cancer. The analyses of IgG recognition of specific exosomal antigens allows for the differentiation of women with benign ovarian masses from ovarian cancer, as well as distinguishing early and late stage ovarian cancers. Thus, the quantitative assessment of IgG reactive with specific tumor-derived exosomal proteins can be used as diagnostic markers for ovarian cancer.

Cell motility and spreading are suppressed by HOXA4 in ovarian cancer cells: possible involvement of beta1 integrin

HOX genes are transcription factors that control morphogenesis, organogenesis and differentiation. Increasing evidence suggests that HOX genes play a role in ovarian cancer progression; however few studies have defined functional roles and mechanisms of action. We showed previously that HOXA4 expression is increased in invasive, compared to noninvasive, epithelial ovarian tumors. However, HOXA4 suppressed cell migration suggesting that elevated HOXA4 expression in invasive tumors constitutes a homeostatic response. In the present study, we used siRNA and forced-expression in multiple cell lines to define the role of HOXA4 in the regulation of transwell migration/invasion and cellular/colony morphology. Knockdown of endogenous HOXA4 increased migration, but not Matrigel invasion, of OVCAR-8 and OVCAR-3 cells. HOXA4 knockdown also increased cell spreading on plastic or fibronectin, reduced cell-cell adhesion, and increased filopodia in two- and three-dimensional cultures. These changes were not associated with significant changes in alphaV or beta3 integrin and E- or N-cadherin. However, down-regulation of HOXA4 significantly reduced beta1 integrin protein levels within cell colonies and cell aggregates, but not of single, nonadherent cells. It had no effect on beta1 integrin, alpha5 integrin, or fibronectin mRNA levels. Conversely, overexpression of HOXA4 in CaOV-3 cells suppressed transwell migration and increased beta1 integrin protein levels. Our results confirm that HOXA4 inhibits cell motility, show that it suppresses cell spreading and filopodia formation while enhancing cell-cell adhesion, and suggest a role for beta1 integrin in mediating these changes. These observations support the hypothesis that overexpression of HOXA4 in invasive ovarian tumors is a homeostatic, invasion-suppressive response.

HOXA13 promotes cancer cell growth and predicts poor survival of patients with esophageal squamous cell carcinoma

Homeobox genes are known to be classic examples of the intimate relationship between embryogenesis and tumorigenesis. Here, we investigated whether inhibition of HOXA13, a member of the homeobox genes, was sufficient to affect the proliferation of esophageal cancer cells in vitro and in vivo, and studied the association between HOXA13 expression and survival of patients with esophageal squamous cell carcinoma (ESCC). HOXA13 expression was permanently knocked down using an RNA interference technique, and cell strain with stable knockdown of HOXA13 protein was established. Colony formation assay showed that the number of colonies in HOXA13 protein-deficient cells was significantly less than that of control cells (P < 0.01). Tumor growth in nude mice showed that the weight and volume of tumors from the HOXA13 knockdown cells was significantly less than that from the control cells (P < 0.01). Then, HOXA13 expression in ESCC specimens and paired noncancerous mucosa was detected by immunohistochemistry, and overexpression of HOXA13 was found to be more pronounced in ESCCs than paired noncancerous mucosa (P < 0.05). Furthermore, the association of HOXA13 expression and disease-free survival time was analyzed in 155 ESCC cases. The median survival time of patients expressing HOXA13 was significantly shorter than HOXA13-negative patients (P = 0.0006). Multivariate analysis indicated that tumor-node-metastasis (TNM) stage and HOXA13 expression were independent predictors of disease-free survival time of patients with ESCC. Our results showed that HOXA13 expression enhanced tumor growth in vitro and in vivo, and was a negative independent predictor of disease-free survival of patients with ESCC.

Inhibition of cancer cell proliferation by designed peptide amphiphiles

HOX genes encode conserved transcription factors that control the morphological diversification along the anteroposterior body axis. HOX proteins bind to DNA through a highly conserved 60 amino acid sequence called the homeodomain, and greater DNA binding specificity and stability are achieved when it forms complexes with cofactors such as PBX and MEIS in humans. In particular, HOX proteins from paralog groups 1-8, interact with PBX proteins via a specific and highly conserved hydrophobic six amino acid sequence localized in the N-terminal region of HOX. In several oncogenic transformations, deregulated HOX gene expression has been observed, indicating an involvement of these transcriptional regulators in carcinogenesis and metastasis. Inhibition of the HOX-PBX interaction could be a strategy to control the abnormal proliferation of these cancer cells. In this study we describe a small designed peptide amphiphile (PA) which self-assembles into micelles and shows inhibition of T3M4 pancreatic cancer cells, K562 leukemia cells and MJT1 melanoma cells while non-cancerous fibroblast NIH 3T3 cells are less affected. This molecule contains three critical regions: a 9-amino-acid sequence designed to disrupt HOX/PBX/DNA complex formation, a 16-amino-acid sequence to deliver the peptide into the cell and a 16-carbon-acyl chain which we show leads to the molecule's self-assembly and significantly enhances the effectiveness of the molecule to slow cell proliferation.