Aberrantly Expressed OTX Homeobox Genes Deregulate B-Cell Differentiation in Hodgkin Lymphoma

OTX Genes in Adult Tissues

OTX homeobox genes have been extensively studied for their role in development, especially in neuroectoderm formation. Recently, their expression has also been reported in adult physiological and pathological tissues, including retina, mammary and pituitary glands, sinonasal mucosa, in several types of cancer, and in response to inflammatory, ischemic, and hypoxic stimuli. Reactivation of OTX genes in adult tissues supports the notion of the evolutionary amplification of functions of genes by varying their temporal expression, with the selection of homeobox genes from the "toolbox" to drive or contribute to different processes at different stages of life. OTX involvement in pathologies points toward these genes as potential diagnostic and/or prognostic markers as well as possible therapeutic targets.

Transcription factor Zhx2 is a checkpoint that programs macrophage polarization and antitumor response

Macrophages are usually educated to tumor-associated macrophages (TAMs) in cancer with pro-tumor functions by tumor microenvironment (TME) and TAM reprogramming has been proposed as a potential tumor immunotherapy strategy. We recently demonstrated the critical role of Zinc-fingers and homeoboxes 2 (Zhx2) in macrophages' metabolic programming. However, whether Zhx2 is responsible for macrophage polarization and TAMs reprogramming is largely unknown. Here, we show that Zhx2 controls macrophage polarization under the inflammatory stimulus and TME. Myeloid-specific deletion of Zhx2 suppresses LPS-induced proinflammatory polarization but promotes IL-4 and TME-induced anti-inflammatory and pro-tumoral phenotypes in murine liver tumor models. Factors in TME, especially lactate, markedly decrease the expression of Zhx2 in TAMs, leading to the switch of TAMs to pro-tumor phenotype and consequent cancer progression. Notably, reduced ZHX2 expression in TAM correlates with poor survival of HCC patients. Mechanistic studies reveal that Zhx2 associates with NF-κB p65 and binds to the Irf1 promoter, leading to transcriptional activation of Irf1 in macrophages. Zhx2 functions in maintaining macrophage polarization by regulating Irf1 transcription, which may be a potential target for macrophage-based cancer immunotherapy.

ZHX2 in health and disease

As a transcriptional factor and the negative regulator of alpha fetal protein (AFP), Zinc fingers and homeoboxes 2 (ZHX2) has a well-established role in protection against hepatocellular carcinoma (HCC). However, recent studies have suggested ZHX2 as an oncogene in clear cell renal cell carcinoma (ccRCC) and triple-negative breast cancer (TNBC). Moreover, mounting evidence has illustrated a much broader role of ZHX2 in multiple cellular processes, including cell proliferation, cell differentiation, lipid metabolism, and immunoregulation. This comprehensive review emphasizes the role of ZHX2 in health and diseases which have been more recently uncovered.

Zinc Fingers and Homeobox Family in Cancer: A Double-Edged Sword

The zinc fingers and homeobox (ZHX) family includes ZHX1, ZHX2, and ZHX3, and their proteins have similar unique structures, containing two C2H2-type zinc finger motifs and four or five HOX-like homeodomains. The members of the ZHX family can form homodimers or heterodimers with each other or with a subunit of nuclear factor Y. Previous studies have suggested that ZHXs can function as positive or negative transcriptional regulators. Recent studies have further revealed their biological functions and underlying mechanisms in cancers. This review summarized the advances of ZHX-mediated functions, including tumor-suppressive and oncogenic functions in cancer formation and progression, the molecular mechanisms, and regulatory functions, such as cancer cell proliferation, migration, invasion, and metastasis. Moreover, the differential expression levels and their association with good or poor outcomes in patients with various malignancies and differential responses to chemotherapy exert opposite functions of oncogene or tumor suppressors. Therefore, the ZHXs act as a double-edged sword in cancers.

Attenuated ZHX3 expression is predictive of poor outcome for liver cancer: Indication for personalized therapy

The zinc-fingers and homeoboxes (ZHX) family members have been characterized as master regulators in cancer initiation and development. The present study performed in silico data-mining with publicly available datasets and immunohistochemistry to assess the expression status of ZHX factors and the corresponding prognostic implications in liver cancer. Increased ZHX3 mRNA expression was associated with favorable overall survival in patients with liver cancer. Subgroups analyses revealed a significant association between the expression of ZHX factors and outcomes in select patient cohorts. Immunohistochemical analysis supported that ZHX3 expression was an independent prognostic indicator for patient survival. These results suggested that dysregulation of ZHX factors is involved in disease progression and ZHX3 expression may serve as a prognostic biomarker for liver cancer.

Genetic Regulation of Vertebrate Forebrain Development by Homeobox Genes

Forebrain development in vertebrates is regulated by transcription factors encoded by homeobox, bHLH and forkhead gene families throughout the progressive and overlapping stages of neural induction and patterning, regional specification and generation of neurons and glia from central nervous system (CNS) progenitor cells. Moreover, cell fate decisions, differentiation and migration of these committed CNS progenitors are controlled by the gene regulatory networks that are regulated by various homeodomain-containing transcription factors, including but not limited to those of the Pax (paired), Nkx, Otx (orthodenticle), Gsx/Gsh (genetic screened), and Dlx (distal-less) homeobox gene families. This comprehensive review outlines the integral role of key homeobox transcription factors and their target genes on forebrain development, focused primarily on the telencephalon. Furthermore, links of these transcription factors to human diseases, such as neurodevelopmental disorders and brain tumors are provided.

Therapeutically Targeting Cancers That Overexpress FOXC1: A Transcriptional Driver of Cell Plasticity, Partial EMT, and Cancer Metastasis

Metastasis accounts for more than 90% of cancer related mortality, thus the most pressing need in the field of oncology today is the ability to accurately predict future onset of metastatic disease, ideally at the time of initial diagnosis. As opposed to current practice, what would be desirable is that prognostic, biomarker-based detection of metastatic propensity and heightened risk of cancer recurrence be performed long before overt metastasis has set in. Without such timely information it will be impossible to formulate a rational therapeutic treatment plan to favorably alter the trajectory of disease progression. In order to help inform rational selection of targeted therapeutics, any recurrence/metastasis risk prediction strategy must occur with the paired identification of novel prognostic biomarkers and their underlying molecular regulatory mechanisms that help drive cancer recurrence/metastasis (i.e. recurrence biomarkers). Traditional clinical factors alone (such as TNM staging criteria) are no longer adequately prognostic for this purpose in the current molecular era. FOXC1 is a pivotal transcription factor that has been functionally implicated to drive cancer metastasis and has been demonstrated to be an independent predictor of heightened metastatic risk, at the time of initial diagnosis. In this review, we present our viewpoints on the master regulatory role that FOXC1 plays in mediating cancer stem cell traits that include cellular plasticity, partial EMT, treatment resistance, cancer invasion and cancer migration during cancer progression and metastasis. We also highlight potential therapeutic strategies to target cancers that are, or have evolved to become, “transcriptionally addicted” to FOXC1. The potential role of FOXC1 expression status in predicting the efficacy of these identified therapeutic approaches merits evaluation in clinical trials.

Transcription factor Zhx2 restricts NK cell maturation and suppresses their antitumor immunity

The maturation and functional competence of natural killer (NK) cells is a tightly controlled process that relies on transcription factors (TFs). Here, we identify transcriptional repressor zinc fingers and homeoboxes 2 (Zhx2) as a novel regulator that restricts NK cell maturation and function. Mice with Zhx2 conditional deletion in NK cells (Zhx2Δ/Δ) showed accumulation of matured NK cells. Loss of Zhx2 enhanced NK cell survival and NK cell response to IL-15. Transcriptomic analysis revealed Zeb2, a key TF in NK cell terminal maturation, as a direct downstream target of Zhx2. Therapeutically, transfer of Zhx2-deficient NK cells resulted in inhibition of tumor growth and metastasis in different murine models. Our findings collectively unmask a previously unrecognized role of Zhx2 as a novel negative regulator in NK cell maturation and highlight its therapeutic potential as a promising strategy to enhance NK cell-mediated tumor surveillance.

Long non-coding RNA SNHG17 promotes proliferation, migration and invasion of glioma cells by regulating the miR-23b-3p/ZHX1 axis

BACKGROUND

Long non-coding RNA (lncRNA) small nucleolar RNA host gene 17 (SNHG17) is a carcinogenic lncRNA in diverse cancers. The expression pattern and mechanisms of SNHG17 in glioma still await verification.

METHODS

Paired glioma samples were enrolled. SNHG17, miR-23b-3p, and zinc-fingers and homeoboxes 1 (ZHX1) mRNA expression were examined by a quantitative real-time polymerase chain reaction (qRT-PCR). SNHG17 short hairpin RNA (shRNA) and miR-23b-3p mimics were transfected into LN229 and U251 cell lines to repress SNHG17 and up-regulate miR-23b-3p expression, respectively. Proliferation, migration and invasion of LN229 and U251 cells were probed by a cell counting kit-8 assay and a Transwell assay. Bioinformatics prediction, dual-luciferase reporter assay, RNA immunoprecipitation assay, qRT-PCR and western blotting were applied to determine the regulatory relationships among SNHG17, miR-23b-3p and ZHX1.

RESULTS

SNHG17 expression was markedly raised in glioma tissues, which was positively correlated with ZHX1 expression and negatively associated with the expression of miR-23b-3p. After transfection of SNHG17 shRNAs into glioma cells, the proliferation, migration and invasion of cancer cells was markedly restrained. miR-23b-3p mimics the function of SHNG17 knockdown. Furthermore, miR-23b-3p was shown to be negatively modulated by SNHG17, and ZHX1 was identified as a target of miR-23b-3p.

CONCLUSIONS

SNHG17 is a "competing endogenous RNA" with respect to modulating ZHX1 expression by adsorbing miR-23b-3p and thereby promoting glioma progression.

Prognostic value and therapeutic implications of ZHX family member expression in human gastric cancer

Despite significant advances in the early diagnosis and effective treatment of gastric cancer, it remains the fourth most common cancer and the second leading cause of cancer-related deaths worldwide. The zinc-fingers and homeoboxes (ZHX) family of transcriptional repressors has been shown to play a role in multiple types of cancer. However, the prognostic significance of ZHX expression in patients with gastric cancer remains unclear. This work studied the association between differential expression of ZHX mRNA and outcomes in patients with gastric cancer using data from the Oncomine, CCLE, Kaplan-Meier-plotter, and cBioPortal databases. Expression of ZHX3 protein was also measured by immunohistochemistry (IHC) in gastric cancer tissues. We found that increased expression of ZHX1 mRNA and decreased expression of ZHX2 and ZHX3 were correlated with better overall survival (OS) in patients with gastric cancer. Further subgroup analyses identified significant associations between ZHX1 expression and survival in select gastric cancer patients. IHC staining confirmed that the over-expression of ZHX3 was associated with worse OS, and multivariate analyses identified ZHX3 expression as an independent prognostic factor. These results suggest that the ZHX family members may serve as distinct biomarkers and prognostic factors for patients with gastric cancer.

Deregulated expression of NKL homeobox genes in T-cell lymphomas

Recently, we have presented a scheme, termed "NKL-code", which describes physiological expression patterns of NKL homeobox genes in early hematopoiesis and in lymphopoiesis including main stages of T-, B- and NK-cell development. Aberrant activity of these genes underlies the generation of hematological malignancies notably T-cell leukemia. Here, we searched for deregulated NKL homeobox genes in main entities of T-cell lymphomas comprising angioimmunoblastic T-cell lymphoma (AITL), anaplastic large cell lymphoma (ALCL), adult T-cell leukemia/lymphoma (ATLL), hepatosplenic T-cell lymphoma (HSTL), NK/T-cell lymphoma (NKTL) and peripheral T-cell lymphoma (PTCL). Our data revealed altogether 19 aberrantly overexpressed genes in these types, demonstrating deregulated NKL homeobox genes involvement in T-cell lymphomas as well. For detailed analysis we focused on NKL homeobox gene MSX1 which is normally expressed in NK-cells. MSX1 was overexpressed in subsets of HSTL patients and HSTL-derived sister cell lines DERL-2 and DERL-7 which served as models to characterize mechanisms of deregulation. We performed karyotyping, genomic and expression profiling, and whole genome sequencing to reveal mutated and deregulated gene candidates, including the fusion gene CD53-PDGFRB. Subsequent knockdown experiments allowed the reconstruction of an aberrant network involved in MSX1 deregulation, including chromatin factors AUTS2 and mutated histone HIST1H3B(K27M). The gene encoding AUTS2 is located at chromosome 7q11 and may represent a basic target of the HSTL hallmark aberration i(7q). Taken together, our findings highlight an oncogenic role for deregulated NKL homeobox genes in T-cell lymphoma and identify MSX1 as a novel player in HSTL, implicated in aberrant NK- and T-cell differentiation.

Attenuated ZHX3 expression serves as a potential biomarker that predicts poor clinical outcomes in breast cancer patients

Background

The ZHX family has recently been in the spotlight as an integrator and an indispensable node in carcinogenesis, whose expression is frequently dysregulated in multiple cancers. The current study provides a novel investigation of the expression profiles of ZHX factors in breast cancer.

Materials and methods

The mRNA levels of ZHXs and follow-up periods in breast cancer patients were mined through the Oncomine, Cancer Cell Line Encyclopedia, bc-GenExMiner, cBioPortal and Kaplan–Meier plotter databases. In addition, ZHX3 protein expression was examined in 98 primary tumor samples by immunohistochemistry to investigate its association with clinicopathological parameters and patient outcomes.

Results

We found that the transcriptional levels of ZHX1, ZHX2 and ZHX3 were not significantly altered in tumor tissues compared with those in nontumor tissues. ZHX2 and ZHX3 mRNA levels were observed to be positively correlated with estrogen receptor and progesterone receptor expression, while ZHX2 mRNA levels were negatively associated with HER2 expression. Survival analyses revealed that high mRNA levels of ZHX2 and ZHX3 correlated with better overall survival in patients with breast cancer. Immunohistochemical analysis revealed that patients with decreased ZHX3 protein levels had poorer outcomes. Multivariate analysis exhibited that ZHX3 expression may serve as an independent high-risk prognostic predictor.

Conclusion

Dysregulated expression of ZHXs may be involved in the progression of breast cancer and could serve as a novel biomarker and potential target for breast cancer.

Use of flow cytometry in the phenotypic diagnosis of hodgkin's lymphoma

Hodgkin's lymphoma (HL) has a unique immunophenotype derived from immunohistochemistry (positive for CD15, CD30, and Pax-5; negative for CD3, CD20 in most cases, and CD45). The knowledge gained over recent years enables better diagnosis, prognosis, and treatment of HL. Flow cytometry as a tool for the diagnosis of classic HL has not been useful in the past due to the difficulty in isolating Reed-Sternberg cells as they are admixed in a rich inflammatory background which consists mainly of T cells, B cells, eosinophils, histiocytes, and plasma cells. However, in the recent past, several studies have tried to identify Reed-Sternberg cells using flow cytometry on fine needle aspiration or tissue biopsy of lymph nodes to confirm or supplement immunohistochemistry staining in diagnosis. Newer and more sensitive tools such as flow cytometry can be used for diagnosis, technology that may have been difficult in the past for diagnosis of this lymphoma subtype. Using flow cytometry, diagnosis is faster and could lead to point-of-care technology especially where we have typical immunophenotype signatures. © 2018 International Clinical Cytometry Society.

Aberrant expression of NKL homeobox gene HLX in Hodgkin lymphoma

NKL homeobox genes are basic regulators of cell and tissue differentiation, many acting as oncogenes in T-cell leukemia. Recently, we described an hematopoietic NKL-code comprising six particular NKL homeobox genes expressed in hematopoietic stem cells and lymphoid progenitors, unmasking their physiological roles in the development of these cell types. Hodgkin lymphoma (HL) is a B-cell malignancy showing aberrant activity of several developmental genes resulting in disturbed B-cell differentiation. To examine potential concordances in abnormal lymphoid differentiation of T- and B-cell malignancies we analyzed the expression of the hematopoietic NKL-code associated genes in HL, comprising HHEX, HLX, MSX1, NKX2-3, NKX3-1 and NKX6-3. Our approach revealed aberrant HLX activity in 8 % of classical HL patients and additionally in HL cell line L-540. Accordingly, to identify upstream regulators and downstream target genes of HLX we used L-540 cells as a model and performed chromosome and genome analyses, comparative expression profiling and functional assays via knockdown and overexpression experiments therein. These investigations excluded chromosomal rearrangements of the HLX locus at 1q41 and demonstrated that STAT3 operated directly as transcriptional activator of the HLX gene. Moreover, subcellular analyses showed highly enriched STAT3 protein in the nucleus of L-540 cells which underwent cytoplasmic translocation by repressing deacetylation. Finally, HLX inhibited transcription of B-cell differentiation factors MSX1, BCL11A and SPIB and of pro-apoptotic factor BCL2L11/BIM, thereby suppressing Etoposide-induced cell death. Collectively, we propose that aberrantly expressed NKL homeobox gene HLX is part of a pathological gene network in HL, driving deregulated B-cell differentiation and survival.

FOXC1, the new player in the cancer sandbox

In recent years, rapidly accumulating evidence implicates forkhead box C1 (FOXC1) in cancer, especially in studies of basal-like breast cancer (BLBC). Other studies have followed suit, demonstrating that FOXC1 is not only a major player in this breast cancer subtype, but also in hepatocellular carcinoma (HCC), endometrial cancer, Hodgkin's lymphoma (HL), and non-Hodgkin's lymphoma (NHL). The FOXC1 gene encodes a transcription factor that is crucial to mesodermal, neural crest, and ocular development, and mutations found in FOXC1 have been found to cause dominantly inherited Axenfeld-Rieger Syndrome (ARS). Interestingly, while FOXC1 missense mutations that are associated with ARS usually reduce gene activity, increased FOXC1 function now appears to be often linked to more aggressive cancer phenotypes in BLBC, HCC, HL, and NHL. This review discusses not only the role of FOXC1 in cancer cell progression, proliferation, differentiation, and metastasis, but also the underlying mechanisms of how FOXC1 can contribute to aggressive cancer phenotypes.

Learning to see again: biological constraints on cortical plasticity and the implications for sight restoration technologies

The 'bionic eye'-so long a dream of the future-is finally becoming a reality with retinal prostheses available to patients in both the US and Europe. However, clinical experience with these implants has made it apparent that the visual information provided by these devices differs substantially from normal sight. Consequently, the ability of patients to learn to make use of this abnormal retinal input plays a critical role in whether or not some functional vision is successfully regained. The goal of the present review is to summarize the vast basic science literature on developmental and adult cortical plasticity with an emphasis on how this literature might relate to the field of prosthetic vision. We begin with describing the distortion and information loss likely to be experienced by visual prosthesis users. We then define cortical plasticity and perceptual learning, and describe what is known, and what is unknown, about visual plasticity across the hierarchy of brain regions involved in visual processing, and across different stages of life. We close by discussing what is known about brain plasticity in sight restoration patients and discuss biological mechanisms that might eventually be harnessed to improve visual learning in these patients.

Roles of zinc-fingers and homeoboxes 1 during the proliferation, migration, and invasion of glioblastoma cells

Zinc-fingers and homeoboxes 1 (ZHX1) is a nuclear transcription repressor and known to be involved in cell differentiation and tumorigenesis. However, the pathophysiological roles of ZHX1 have not been characterized in glioblastoma. We examined ZHX1 expression in glioblastoma patients' tissues and analyzed overall survival of the patients based on expression level of ZHX1. We also examined the effects of ZHX1 on proliferation and motility of glioblastoma cells. In silico analysis and immunohistochemical studies showed that the messenger RNA and protein expressions of ZHX1 were higher in the tissues of glioblastoma patients than in normal brain tissues, and that its overexpression was associated with reduced survival. In vitro, the downregulation of ZHX1 decreased the proliferation, migration, and invasion of glioblastoma cells, whereas its upregulation had the opposite effects. In addition, we showed ZHX1 could contribute to glioblastoma progression via the regulations of TWIST1 and SNAI2. Taken together, this study demonstrates that ZHX1 plays crucial roles in the progression of glioblastoma, and its findings suggest that ZHX1 be viewed as a potential prognostic maker and therapeutic target of glioblastoma.

OTX2 expression contributes to proliferation and progression in Myc-amplified medulloblastoma

Medulloblastoma is one of the most prevalent pediatric brain malignancies, accounting for approximately 20% of all primary CNS tumors in children under the age of 19. OTX2 is the member of a highly conserved family of bicoid-like homeodomain transcription factors responsible for the regulation of cerebellar development and of current investigational interest in the tumorigenesis of medulloblastoma. Recent studies have revealed that Group 3 and Group 4 medulloblastomas show marked overexpression of OTX2 with a concurrent amplification of the MYC and MYCN oncogenes, respectively, correlating with anaplasticity and unfavorable patient outcomes. More recent attempts at elucidating the mechanism of OTX2-driven oncogenesis at the cellular level has also revealed that OTX2 may confer stem-cell like properties to tumor cells via epigenetic regulation. The review seeks to define the interaction pathways and binding partners involved in OTX2 function, its usefulness as a molecular marker for risk stratification and prognosis, and the mechanism by which it drives tumor maintenance. Additionally, it will preview unpublished data by our group highlighting the unanticipated involvement of OTX2 in the control of cellular metabolism.

Identification of a tumor suppressor network in T-cell leukemia

To identify novel cancer-related genes targeted by copy number alterations, we performed genomic profiling of T-cell acute lymphoblastic leukemia (T-ALL) cell lines. In 3/8, we identified a shared deletion at chromosomal position 2p16.3-p21. Within the minimally deleted region, we recognized several candidate tumor suppressor (TS) genes, including FBXO11 and FOXN2. An additional deletion at chromosome 14q23.2-q32.11 included FOXN3, highlighting this class of FOX genes as potential TS. Quantitative expression analyses of FBXO11, FOXN2, and FOXN3 confirmed reduced transcript levels in the identified cell lines. Moreover, reduced expression of these genes was also observed in about 7% of T-ALL patients, showing their clinical relevance in this malignancy. Bioinformatic analyses revealed concurrent reduction of FOXN2 and/or FOXN3 together with homeobox gene ZHX1. Consistently, experiments demonstrated that both FOXN2 and FOXN3 directly activated transcription of ZHX1. Taken together, we identified novel TS genes forming a regulatory network in T-cell development and leukemogenesis.

ZHX1 Promotes the Proliferation, Migration and Invasion of Cholangiocarcinoma Cells

Zinc-fingers and homeoboxes 1 (ZHX1) is a transcription repressor that has been associated with the progressions of hepatocellular carcinoma, gastric cancer, and breast cancer. However, the functional roles of ZHX1 in cholangiocarcinoma (CCA) have not been determined. We investigated the expression and roles of ZHX1 during the proliferation, migration, and invasion of CCA cells. In silico analysis and immunohistochemical studies showed amplification and overexpression of ZHX1 in CCA tissues. Furthermore, ZHX1 knockdown using specific siRNAs decreased CCA cell proliferation, migration, and invasion, whereas ZHX1 overexpression promoted all three characteristics. In addition, results suggested EGR1 might partially mediate the effect of ZHX1 on the proliferation of CCA cells. Taken together, these results show ZHX1 promotes CCA cell proliferation, migration, and invasion, and present ZHX1 as a potential target for the treatment of CCA.

Aberrant expression of homeobox gene SIX1 in Hodgkin lymphoma

In Hodgkin lymphoma (HL) we recently identified deregulated expression of homeobox genes MSX1 and OTX2 which are physiologically involved in development of the embryonal neural plate border region. Here, we examined in HL homeobox gene SIX1 an additional regulator of this embryonal region mediating differentiation of placodal precursors. SIX1 was aberrantly activated in 12 % of HL patient samples in silico, indicating a pathological role in a subset of this B-cell malignancy. In addition, SIX1 expression was detected in HL cell lines which were used as models to reveal upstream factors and target genes of this basic developmental regulator. We detected increased copy numbers of the SIX1 locus at chromosome 14q23 correlating with enhanced expression while chromosomal translocations were absent. Moreover, comparative expression profiling data and pertinent gene modulation experiments indicated that the WNT-signalling pathway and transcription factor MEF2C regulate SIX1 expression. Genes encoding the transcription factors GATA2, GATA3, MSX1 and SPIB – all basic lymphoid regulators - were identified as targets of SIX1 in HL. In addition, cofactors EYA1 and TLE4, respectively, contrastingly mediated activation and suppression of SIX1 target gene expression. Thus, the protein domain interfaces may represent therapeutic targets in SIX1-positive HL subsets. Collectively, our data reveal a gene regulatory network with SIX1 centrally deregulating lymphoid differentiation and support concordance of lymphopoiesis/lymphomagenesis and developmental processes in the neural plate border region.