CTIP2 expression in human head and neck squamous cell carcinoma is linked to poorly differentiated tumor status

The function of BCL11B in base excision repair contributes to its dual role as an oncogene and a haplo-insufficient tumor suppressor gene

Genetic studies in mice and human cancers established BCL11B as a haploinsufficient tumor suppressor gene. Paradoxically, BCL11B is overexpressed in some human cancers where its knockdown is synthetic lethal. We identified the BCL11B protein in a proximity-dependent biotinylation screen performed with the DNA glycosylase NTHL1. In vitro DNA repair assays demonstrated that both BCL11B and a small recombinant BCL11B213-560 protein lacking transcription regulation potential can stimulate the enzymatic activities of two base excision repair (BER) enzymes: NTHL1 and Pol β. In cells, BCL11B is rapidly recruited to sites of DNA damage caused by laser microirradiation. BCL11B knockdown delays, whereas ectopic expression of BCL11B213-560 accelerates, the repair of oxidative DNA damage. Inactivation of one BCL11B allele in TK6 lymphoblastoid cells causes an increase in spontaneous and radiation-induced mutation rates. In turn, ectopic expression of BCL11B213-560 cooperates with the RAS oncogene in cell transformation by reducing DNA damage and cellular senescence. These findings indicate that BCL11B functions as a BER accessory factor, safeguarding normal cells from acquiring mutations. Paradoxically, it also enables the survival of cancer cells that would otherwise undergo senescence or apoptosis due to oxidative DNA damage resulting from the elevated production of reactive oxygen species.

BCL11B expression in hepatocellular carcinoma relates to chemosensitivity and clinical prognosis

INTRODUCTION

B-cell lymphoma/leukemia 11B (BCL11B) is a subunit of SWI/SNF chromatin remodeling complexes and functions in cell cycle regulation and apoptosis upon DNA replication stress and damages via transcription. Many malignancies were reported to exhibit changes in BCL11B gene expression; however, no study has focused on the relationship between BCL11B and hepatocellular carcinoma, which potentially exhibits DNA replication stress and damages upon its oncogenesis. Thus, in this study, we examined the molecular characterization of BCL11B expression in hepatocellular carcinoma.

METHODS AND RESULTS

The cumulative progression-free survival and overall survival were significantly longer in the clinical cases of BCL11B-negative hepatocellular carcinoma than BCL11B-positve cases. Microarray and real-time PCR analyses in hepatocellular carcinoma cell lines indicated a correlation between BCL11B and GATA6, a gene reported to be correlated with oncogenic activities and resistance to anthracycline, which is often used for hepatocellular carcinoma chemotherapy. Consequently, BCL11B-overexpressing cell lines exhibited resistance to anthracycline in cell growth assays and the resistance has been evidenced by the increased expression of BCL-xL in cell lines. The results were supported by the analyses of human HCC samples showing the correlation between BCL11B and GATA6 expressions.

DISCUSSIONS AND CONCLUSION

Our results indicated that overexpression of BCL11B amplifies GATA6 expression in hepatocellular carcinoma in vitro and in vivo that leads to anti-apoptotic signal activation, and induces resistance to chemotherapy, which influenced the postoperative prognosis.

CTIP2 and lipid metabolism: regulation in skin development and associated diseases

INTRODUCTION

COUP-TF INTERACTING PROTEIN 2 (CTIP2) is a crucial transcription factor exhibiting its control through coupled modulation of epigenetic modification and transcriptional regulation of key genes related to skin, immune, and nervous system development. Previous studies have validated the essential role of CTIP2 in skin development and maintenance, propagating its effects in epidermal permeability barrier (EPB) homeostasis, wound healing, inflammatory diseases, and epithelial cancers. Lipid metabolism dysregulation, on the other hand, has also established its independent emerging role over the years in normal skin development and various skin-associated ailments. This review focuses on the relatively unexplored connections between CTIP2-mediated control of lipid metabolism and alteration of EPB homeostasis, delayed wound healing, inflammatory diseases exacerbation, and cancer promotion and progression.

AREAS COVERED

Here we have discussed the intricate interplay of various endogenous lipids and lipoproteins accompanying skin development and associated disease processes and the possible link to CTIP2-mediated regulation of lipid metabolism.

EXPERT OPINION

Establishing the link between CTIP2 and lipid metabolism alterations in the context of skin morphogenesis and diverse types of skin diseases including cancer can help us identify novel targets for effective therapeutic intervention.

Nuclear import of BCL11B is mediated by a classical nuclear localization signal and not the Krüppel-like zinc fingers

The Krüppel-like transcription factor BCL11B is characterized by wide tissue distribution and crucial functions in key developmental and cellular processes and various pathologies including cancer or HIV infection. Although basics of BCL11B activity and relevant interactions with other proteins were uncovered, how this exclusively nuclear protein localizes to its compartment remained unclear. Here, we demonstrate that unlike other KLFs, BCL11B does not require the C-terminal DNA-binding domain to pass through the nuclear envelope but encodes an independent, previously unidentified nuclear localization signal (NLS) which is located distantly from the zinc finger domains and fulfills the essential criteria of an autonomous NLS. First, it can redirect a heterologous cytoplasmic protein to the nucleus. Second, its mutations cause aberrant localization of the protein of origin. Finally, we provide experimental and in silico evidences of the direct interaction with importin alpha. The relative conservation of this motif allows formulating a consensus sequence (K/R)K-X13-14-KR+K++ which can be found in all BCL11B orthologues among vertebrates and in the closely related protein BCL11A.

Discrimination of Cancer Stem Cell Markers ALDH1A1, BCL11B, BMI-1, and CD44 in Different Tissues of HNSCC Patients

Cancer stem cells (CSCs) are accountable for the progress of head and neck squamous cell carcinoma (HNSCC). This exploratory study evaluated the expression of molecular CSC markers in different tissues of HNSCC patients. Tissue specimens of primary tumor, lymph node metastases and macroscopically healthy mucosa of 12 consecutive HNSCC patients, that were treated with surgery and adjuvant radio(chemo)therapy upon indication, were collected. Samples were assessed for the expression of p16 as a surrogate for HPV-related disease and different molecular stem cell markers (ALDH1A1, BCL11B, BMI-1, and CD44). In the cohort, seven patients had HPV-related HNSCC; six thereof were oropharyngeal squamous cell carcinoma. While expression of BMI-1 and BCL11B was significantly lower in healthy mucosa than both tumor and lymph node metastasis, there were no differences between tumor and lymph node metastasis. In the HPV-positive sub-cohort, these differences remained significant for BMI-1. However, no significant differences in these three tissues were found for ALDH1A1 and CD44. In conclusion, this exploratory study shows that CSC markers BMI-1 and BCL11B discriminate between healthy and cancerous tissue, whereas ALDH1A1 and CD44 were expressed to a comparable extent in healthy mucosa and cancerous tissues.

Unveiling the N-Terminal Homodimerization of BCL11B by Hybrid Solvent Replica-Exchange Simulations

Transcription factors play a crucial role in regulating biological processes such as cell growth, differentiation, organ development and cellular signaling. Within this group, proteins equipped with zinc finger motifs (ZFs) represent the largest family of sequence-specific DNA-binding transcription regulators. Numerous studies have proven the fundamental role of BCL11B for a variety of tissues and organs such as central nervous system, T cells, skin, teeth, and mammary glands. In a previous work we identified a novel atypical zinc finger domain (CCHC-ZF) which serves as a dimerization interface of BCL11B. This domain and formation of the dimer were shown to be critically important for efficient regulation of the BCL11B target genes and could therefore represent a promising target for novel drug therapies. Here, we report the structural basis for BCL11B-BCL11B interaction mediated by the N-terminal ZF domain. By combining structure prediction algorithms, enhanced sampling molecular dynamics and fluorescence resonance energy transfer (FRET) approaches, we identified amino acid residues indispensable for the formation of the single ZF domain and directly involved in forming the dimer interface. These findings not only provide deep insight into how BCL11B acquires its active structure but also represent an important step towards rational design or selection of potential inhibitors.

Bcl11b/Ctip2 in Skin, Tooth, and Craniofacial System

Ctip2/Bcl11b is a zinc finger transcription factor with dual action (repression/activation) that couples epigenetic regulation to gene transcription during the development of various tissues. It is involved in a variety of physiological responses under healthy and pathological conditions. Its role and mechanisms of action are best characterized in the immune and nervous systems. Furthermore, its implication in the development and homeostasis of other various tissues has also been reported. In the present review, we describe its role in skin development, adipogenesis, tooth formation and cranial suture ossification. Experimental data from several studies demonstrate the involvement of Bcl11b in the control of the balance between cell proliferation and differentiation during organ formation and repair, and more specifically in the context of stem cell self-renewal and fate determination. The impact of mutations in the coding sequences of Bcl11b on the development of diseases such as craniosynostosis is also presented. Finally, we discuss genome-wide association studies that suggest a potential influence of single nucleotide polymorphisms found in the 3’ regulatory region of Bcl11b on the homeostasis of the cardiovascular system.

Role of cancer stem cell markers ALDH1, BCL11B, BMI-1, and CD44 in the prognosis of advanced HNSCC

Purpose

Cancer stem cells (CSCs) are held accountable for the progress of head and neck squamous cell carcinoma (HNSCC). In the presented study, the authors evaluated the prognostic value of CSC markers in two particular HNSCC cohorts.

Methods

This two cohort study consisted of 85 patients with advanced stage HNSCC, treated with primary radio(chemo)therapy (pRCT), and 95 patients with HNSCC, treated with surgery and partially adjuvant radio(chemo)therapy. Overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS) were assessed. Samples were assessed for the expression of different molecular stem cell markers (ALDH1, BCL11B, BMI‑1, and CD44).

Results

In the pRCT cohort, none of the baseline patient and tumor features exhibited a statistically significant relation with survival in either the cohort or the human papillomavirus (HPV)-stratified subcohorts. High expression of BMI‑1 significantly decreased OS and DFS, while high expression of CD44 decreased all modes of survival. Multivariate analysis showed significant prognostic influence for all tested CSC markers, with high BMI‑1 and CD44 decreasing survival (BMI-1: OS, DFS, DSS; CD44: OS, DFS) and high ALDH1 and BCL11B showing a beneficial effect on survival (ALDH1: OS, DFS; BCL11B: OS, DSS). In the surgical cohort, classical prognosticators such as HPV status, R1 resection, and nodal status in HPV-negative HNSCC played a significant role, but the tested CSC markers showed no significant effect on prognosis.

Conclusion

Although validation in independent cohorts is still needed, testing for CSC markers in patients with advanced or late stage HNSCC might be beneficial, especially if many comorbidities exist or disease is irresectable. The findings might guide the development and earlier use of targeted therapies in the future.

Electronic supplementary material

The online version of this article (10.1007/s00066-020-01653-5) contains supplementary material, which is available to authorized users.

The N-Terminal CCHC Zinc Finger Motif Mediates Homodimerization of Transcription Factor BCL11B

The BCL11B gene encodes a Krüppel-like, sequence-specific zinc finger (ZF) transcription factor that acts as either a repressor or an activator, depending on its posttranslational modifications. The importance of BCL11B in numerous biological processes in multiple organs has been well established in mouse knockout models. The phenotype of the first de novo monoallelic germ line missense mutation in the BCL11B gene (encoding N441K) strongly implies that the mutant protein acts in a dominant-negative manner by neutralizing the unaffected protein through the formation of a nonfunctional dimer. Using a Förster resonance energy transfer-assisted fluorescence-activated cell sorting (FACS-FRET) assay and affinity purification followed by mass spectrometry (AP-MS), we show that the N-terminal CCHC zinc finger motif is necessary and sufficient for the formation of the BCL11B dimer. Mutation of the CCHC ZF in BCL11B abolishes its transcription-regulatory activity. In addition, unlike wild-type BCL11B, this mutant is incapable of inducing cell cycle arrest and protecting against DNA damage-driven apoptosis. Our results confirm the BCL11B dimerization hypothesis and prove its importance for BCL11B function. By mapping the relevant regions to the CCHC domain, we describe a previously unidentified mechanism of transcription factor homodimerization.

NOTCH Signaling Regulates Asymmetric Cell Fate of Fast- and Slow-Cycling Colon Cancer-Initiating Cells

Colorectal cancer cells with stem-like properties, referred to as colon cancer-initiating cells (CCIC), have high tumorigenic potential. While CCIC can differentiate to promote cellular heterogeneity, it remains unclear whether CCIC within a tumor contain distinct subpopulations. Here, we describe the co-existence of fast- and slow-cycling CCIC, which can undergo asymmetric division to generate each other, highlighting CCIC plasticity and interconvertibility. Fast-cycling CCIC express markers, such as LGR5 and CD133, rely on MYC for their proliferation, whereas slow-cycling CCIC express markers, such as BMI1 and hTERT, are independent of MYC. NOTCH signaling promotes asymmetric cell fate, regulating the balance between these two populations. Overall, our results illuminate the basis for CCIC heterogeneity and plasticity by defining a direct interconversion mechanism between slow- and fast-cycling CCIC. Cancer Res; 76(11); 3411-21. ©2016 AACR.

Kinetic analysis of BCL11B multisite phosphorylation-dephosphorylation and coupled sumoylation in primary thymocytes by multiple reaction monitoring mass spectroscopy

Transcription factors with multiple post-translational modifications (PTMs) are not uncommon, but comprehensive information on site-specific dynamics and interdependence is comparatively rare. Assessing dynamic changes in the extent of PTMs has the potential to link multiple sites both to each other and to biological effects observable on the same time scale. The transcription factor and tumor suppressor BCL11B is critical to three checkpoints in T-cell development and is a target of a T-cell receptor-mediated MAP kinase signaling. Multiple reaction monitoring (MRM) mass spectroscopy was used to assess changes in relative phosphorylation on 18 of 23 serine and threonine residues and sumoylation on one of two lysine resides in BCL11B. We have resolved the composite phosphorylation-dephosphorylation and sumoylation changes of BCL11B in response to MAP kinase activation into a complex pattern of site-specific PTM changes in primary mouse thymocytes. The site-specific resolution afforded by MRM analyses revealed four kinetic patterns of phosphorylation and one of sumoylation, including both rapid simultaneous site-specific increases and decreases at putative MAP kinase proline-directed phosphorylation sites, following stimulation. These data additionally revealed a novel spatiotemporal bisphosphorylation motif consisting of two kinetically divergent proline-directed phosphorylation sites spaced five residues apart.

SWI/SNF chromatin remodeling complexes and cancer

The identification of mutations and deletions in the SMARCB1 locus in chromosome band 22q11.2 in pediatric rhabdoid tumors provided the first evidence for the involvement of the SWI/SNF chromatin remodeling complex in cancer. Over the last 15 years, alterations in more than 20 members of the complex have been reported in a variety of human tumors. These include germline mutations and copy number alterations in SMARCB1, SMARCA4, SMARCE1, and PBRM1 that predispose carriers to both benign and malignant neoplasms. Somatic mutations, structural abnormalities, or epigenetic modifications that lead to reduced or aberrant expression of complex members have now been reported in more than 20% of malignancies, including both solid tumors and hematologic disorders in both children and adults. In this review, we will highlight the role of SMARCB1 in cancer as a paradigm for other tumors with alterations in SWI/SNF complex members and demonstrate the broad spectrum of mutations observed in complex members in different tumor types.

Expression of ABCG2 and Bmi-1 in oral potentially malignant lesions and oral squamous cell carcinoma

Early diagnosis is vital for effective treatment of oral squamous cell carcinoma (OSCC). The optimal time for clinical intervention is prior to malignancy when patients present with oral potentially malignant lesions such as leukoplakia or erythroplakia. Transformation rates for oral dysplasia vary greatly and more rigorous methods are needed to predict the malignant potential of oral lesions. We hypothesized that the expression of two putative stem cell markers, ABCG2 and Bmi-1, would correlate with disease severity for non diseased, potentially malignant and OSCC specimens and cell lines derived from an equivalent range of tissues. We compared immunoreactive protein and relative gene expression of ABCG2 and Bmi-1 in eight cell lines derived from source tissues ranging in disease severity from normal (OKF6-TERT2) through mild and moderate/severe dysplasia (DOK, POE-9n) to OSCC (PE/CA-PJ15, SCC04, SCC25, SCC09, SCC15). We also analyzed immunoreactive protein expression of ABCG2 and Bmi-1 in 189 tissue samples with the same range of disease severity. A trend between oral lesion severity to ABCG2 and Bmi-1 immunostain intensity was observed. Flow cytometry of oral cell lines confirmed this trend and gave good correlation with RT-PCR results for ABCG2 (r = 0.919, P = 0.001; Pearson) but not Bmi-1 (r = −0.311). The results provide evidence of increased density of ABCG2 and Bmi-1-positive populations in malignant and oral potentially malignant lesions and derived cell lines, but that intragroup variability within IHC, flow cytometry, and RT-PCR results compromise the diagnostic potential of these techniques for discriminating oral dysplasia from normal tissue or OSCC.

CTIP2 is a negative regulator of P-TEFb

The positive transcription elongation factor b (P-TEFb) is involved in physiological and pathological events including inflammation, cancer, AIDS, and cardiac hypertrophy. The balance between its active and inactive form is tightly controlled to ensure cellular integrity. We report that the transcriptional repressor CTIP2 is a major modulator of P-TEFb activity. CTIP2 copurifies and interacts with an inactive P-TEFb complex containing the 7SK snRNA and HEXIM1. CTIP2 associates directly with HEXIM1 and, via the loop 2 of the 7SK snRNA, with P-TEFb. In this nucleoprotein complex, CTIP2 significantly represses the Cdk9 kinase activity of P-TEFb. Accordingly, we show that CTIP2 inhibits large sets of P-TEFb- and 7SK snRNA-sensitive genes. In hearts of hypertrophic cardiomyopathic mice, CTIP2 controls P-TEFb-sensitive pathways involved in the establishment of this pathology. Overexpression of the β-myosin heavy chain protein contributes to the pathological cardiac wall thickening. The inactive P-TEFb complex associates with CTIP2 at the MYH7 gene promoter to repress its activity. Taken together, our results strongly suggest that CTIP2 controls P-TEFb function in physiological and pathological conditions.

COUP-TF-interacting protein-2 (Ctip2): driving the coupé of sphingolipid biosynthesis in the epidermis

Previous studies using chicken ovalbumin upstream promoter transcription factor (COUP-TF)-interacting protein 2 (Ctip2) knockout mice have demonstrated the importance of this transcription factor for the formation of the epidermal permeability barrier. Because sphingolipids are crucial in generating the barrier, in this issue Indra and colleagues show, perhaps not surprisingly, that Ctip2 has a key role in sphingolipid metabolism. Thus, Ctip2 gene ablation alters sphingolipid levels and expression of genes encoding sphingolipid-metabolizing enzymes, in some cases by direct binding to their promoters. Abnormalities in Ctip2 could therefore underlie skin disorders characterized by an aberrant epidermal permeability barrier.

Cancer stem cell markers in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the world's top ten most common cancers. Current survival rates are poor with only 50% of patients expected to survive five years after diagnosis. The poor survival rate of HNSCC is partly attributable to the tendency for diagnosis at the late stage of the disease. One of the reasons for treatment failure is thought to be related to the presence of a subpopulation of cells within the tumour called cancer stem cells (CSCs). CSCs display stem cell-like characteristics that impart resistance to conventional treatment modalities and promote tumour initiation, progression, and metastasis. Specific markers for this population have been investigated in the hope of developing a deeper understanding of their role in the pathogenesis of HNSCC and elucidating novel therapeutic strategies.

Reduced level of the BCL11B protein is associated with adult T-cell leukemia/lymphoma

Background

Adult T-cell leukemia/lymphoma (ATLL) develops in a small proportion of human T-cell leukemia virus type I (HTLV-I)-infected individuals. However, the mechanism by which HTLV-I causes ATLL has not been fully elucidated. To provide fundamental insights into the multistep process of leukemogenesis, we have mapped the chromosomal abnormalities in 50 ATLL cases to identify potential key regulators of ATLL.

Results

The analysis of breakpoints in one ATLL case with the translocations t(14;17)(q32;q22-23) resulted in the identification of a Kruppel zinc finger gene, BCL11B, which plays a crucial role in T-cell development. Among the 7 ATLL cases that we examined by immunofluorescence analysis, 4 displayed low and one displayed moderate BCL11B signal intensities. A dramatically reduced level of the BCL11B protein was also found in HTLV-I-positive T-cell lines. The ectopic expression of BCL11B resulted in significant growth suppression in ATLL-derived cell lines but not in Jurkat cells.

Conclusions

Our genetic and functional data provide the first evidence that a reduction in the level of the BCL11B protein is a key event in the multistep progression of ATLL leukemogenesis.

Cancer stem cells, microRNAs, and therapeutic strategies including natural products

Embryonic stem cells divide continuously and differentiate into organs through the expression of specific transcription factors at specific time periods. Differentiated adult stem cells on the other hand remain in quiescent state and divide by receiving cues from the environment (extracellular matrix or niche), as in the case of wound healing from tissue injury or inflammation. Similarly, it is believed that cancer stem cells (CSCs), forming a smaller fraction of the tumor bulk, also remain in a quiescent state. These cells are capable of initiating and propagating neoplastic growth upon receiving environmental cues, such as overexpression of growth factors, cytokines, and chemokines. Candidate CSCs express distinct biomarkers that can be utilized for their identification and isolation. This review focuses on the known and candidate cancer stem cell markers identified in various solid tumors and the promising future of disease management and therapy targeted at these markers. The review also provides details on the differential expression of microRNAs (miRNAs), and the miRNA- and natural product-based therapies that could be applied for the treatment of cancer stem cells.

A dual function of Bcl11b/Ctip2 in hippocampal neurogenesis

The transcription factor Bcl11b/Ctip2 promotes hippocampal progenitor proliferation and neural differentiation in a non-cell autonomous manner by regulating the expression of the cell adhesion molecule Desmoplakin. Forebrain-specific ablation causes defective spatial learning and memory.

The development of the dentate gyrus is characterized by distinct phases establishing a durable stem-cell pool required for postnatal and adult neurogenesis. Here, we report that Bcl11b/Ctip2, a zinc finger transcription factor expressed in postmitotic neurons, plays a critical role during postnatal development of the dentate gyrus. Forebrain-specific ablation of Bcl11b uncovers dual phase-specific functions of Bcl11b demonstrated by feedback control of the progenitor cell compartment as well as regulation of granule cell differentiation, leading to impaired spatial learning and memory in mutants. Surprisingly, we identified Desmoplakin as a direct transcriptional target of Bcl11b. Similarly to Bcl11b, postnatal neurogenesis and granule cell differentiation are impaired in Desmoplakin mutants. Re-expression of Desmoplakin in Bcl11b mutants rescues impaired neurogenesis, suggesting Desmoplakin to be an essential downstream effector of Bcl11b in hippocampal development. Together, our data define an important novel regulatory pathway in hippocampal development, by linking transcriptional functions of Bcl11b to Desmoplakin, a molecule known to act on cell adhesion.

The role of BCL11B in regulating the proliferation of human naive T cells

The effect of the B-cell chronic lymphocytic leukemia/lymphoma 11B gene (BCL11B) on human T-cell regulation remains unclear. To characterize the functions of BCL11B, recombinant BCL11B and BCL11B siRNA were transfected into human naive T cells to overexpress or knock down BCL11B expression, respectively. After BCL11B overexpression, the proliferation ability and the T-helper (Th) subset were increased, whereas no significant alteration in the expression pattern and clonality of the T-cell receptor Vβ subfamilies was observed. After BCL11B knockdown, a similar distribution of Vβ subfamilies was detected in the naive T cells; however, the proliferation capacity substantially decreased. Global gene expression profiling revealed that the dysregulated genes were mainly involved in T-cell activation and proliferation. BCL11B could selectively promote Th-cell differentiation because of increased CXCL10 and CXCL11 expression. BCL11B suppression may inhibit proliferation and induce apoptosis, which may relate to changes in the expression of CFLAR-CASP8-CASP10 in the mitochondrial pathways. In conclusion, BCL11B is required for T-cell survival; its overexpression could effectively increase the T-cell activation and proliferation abilities and Th-cell differentiation as well.

Delayed cutaneous wound healing and aberrant expression of hair follicle stem cell markers in mice selectively lacking Ctip2 in epidermis

BACKGROUND

COUP-TF interacting protein 2 [(Ctip2), also known as Bcl11b] is an important regulator of skin homeostasis, and is overexpressed in head and neck cancer. Ctip2(ep-/-) mice, selectively ablated for Ctip2 in epidermal keratinocytes, exhibited impaired terminal differentiation and delayed epidermal permeability barrier (EPB) establishment during development, similar to what was observed in Ctip2 null (Ctip2(-/-)) mice. Considering that as an important role of Ctip2, and the fact that molecular networks which underlie cancer progression partially overlap with those responsible for tissue remodeling, we sought to determine the role of Ctip2 during cutaneous wound healing.

METHODOLOGY/PRINCIPAL FINDINGS

Full thickness excisional wound healing experiments were performed on Ctip2(L2/L2) and Ctip2(ep-/-) animals per time point and used for harvesting samples for histology, immunohistochemistry (IHC) and immunoblotting. Results demonstrated inherent defects in proliferation and migration of Ctip2 lacking keratinocytes during re-epithelialization. Mutant mice exhibited reduced epidermal proliferation, delayed keratinocyte activation, altered cell-cell adhesion and impaired ECM development. Post wounding, Ctip2(ep-/-) mice wounds displayed lack of E-Cadherin suppression in the migratory tongue, insufficient expression of alpha smooth muscle actin (alpha SMA) in the dermis, and robust induction of K8. Importantly, dysregulated expression of several hair follicle (HF) stem cell markers such as K15, NFATc1, CD133, CD34 and Lrig1 was observed in mutant skin during wound repair.

CONCLUSIONS/SIGNIFICANCE

Results confirm a cell autonomous role of keratinocytic Ctip2 to modulate cell migration, proliferation and/or differentiation, and to maintain HF stem cells during cutaneous wounding. Furthermore, Ctip2 in a non-cell autonomous manner regulated granulation tissue formation and tissue contraction during wound closure.

Two stem cell markers, ATP-binding cassette, G2 subfamily (ABCG2) and BMI-1, predict the transformation of oral leukoplakia to cancer: a long-term follow-up study

BACKGROUND

Although oral leukoplakia (OL) is the best-known potentially malignant disorder, the risk of OL malignant transformation is difficult to assess. ATP-binding cassette, G2 subfamily (ABCG2) and BMI-1 are stem cell markers that have been found to be associated with head and neck tumorigenesis. The objective of the current study was to evaluate the usefulness of ABCG2 and BMI-1 in predicting OL transformation.

METHODS

In a retrospective cohort of 135 patients with OL from the study institution who had a mean follow-up of 5.5 years, 32 developed cancer between 1985 and 2008. The expression of ABCG2 and BMI-1 was determined using immunohistochemistry in samples from these patients, and included untransformed OL (n = 103) and malignant-transformed OL (n = 32). The association between protein expression and clinicopathological parameters and transformation was analyzed.

RESULTS

Expression of ABCG2 and BMI-1 was observed in 58 (43.0%) and 44 (32.6%) of 135 patients, respectively. The correlation between ABCG2 and BMI-1 expression was significant (P = .024). Kaplan-Meier analysis revealed that 37.9% of patients with ABCG2 positivity developed cancer compared with 13.0% of patients with ABCG2 negativity (P = .014, log-rank test). Approximately 40.9% of patients with BMI-1 positivity developed cancer compared with 15.4% of patients with BMI-1 negativity (P = .029, log-rank test). Multivariate analysis revealed that ABCG2 and BMI-1 expression was associated with a 3.24-fold (95% confidence interval [95% CI], 1.31-7.98; P = .011) and 4.03-fold (95% CI, 1.59-10.26; P = .003) increased the risk of transformation, respectively.

CONCLUSIONS

ABCG2 and BMI-1 expression was found to be associated with the development of oral cancer in a large cohort of patients with OL for whom long-term follow-up was available, which suggests that ABCG2 and BMI-1 may be used as predictors of OL transformation.

Local interstitial delivery of z-butylidenephthalide by polymer wafers against malignant human gliomas

We have shown that the natural compound z-butylidenephthalide (Bdph), isolated from the chloroform extract of Angelica sinensis, has antitumor effects. Because of the limitation of the blood-brain barrier, the Bdph dosage required for treatment of glioma is relatively high. To solve this problem, we developed a local-release system with Bdph incorporated into a biodegradable polyanhydride material, p(CPP-SA; Bdph-Wafer), and investigated its antitumor effects. On the basis of in vitro release kinetics, we demonstrated that the Bdph-Wafer released 50% of the available Bdph by the sixth day, and the release reached a plateau phase (90% of Bdph) by the 30th day. To investigate the in situ antitumor effects of the Bdph-Wafer on glioblastoma multiforme (GBM), we used 2 xenograft animal models-F344 rats (for rat GBM) and nude mice (for human GBM)-which were injected with RG2 and DBTRG-05MG cells, respectively, for tumor formation and subsequently treated subcutaneously with Bdph-Wafers. We observed a significant inhibitory effect on tumor growth, with no significant adverse effects on the rodents. Moreover, we demonstrated that the antitumor effect of Bdph on RG2 cells was via the PKC pathway, which upregulated Nurr77 and promoted its translocation from the nucleus to the cytoplasm. Finally, to study the effect of the interstitial administration of Bdph in cranial brain tumor, Bdph-Wafers were surgically placed in FGF-SV40 transgenic mice. Our Bdph-Wafer significantly reduced tumor size in a dose-dependent manner. In summary, our study showed that p(CPP-SA) containing Bdph delivered a sufficient concentration of Bdph to the tumor site and effectively inhibited the tumor growth in the glioma.

Proteome analysis reveals new mechanisms of Bcl11b-loss driven apoptosis

The Bcl11b protein was shown to be important for a variety of functions such as T cell differentiation, normal development of central nervous system, and DNA damage response. Malignant T cells undergo apoptotic cell death upon BCL11B down-regulation, however, the detailed mechanism of cell death is not fully understood yet. Here we employed two-dimensional difference in-gel electrophoresis (2D-DIGE), mass spectrometry and cell biological experiments to investigate the role of Bcl11b in malignant T cell lines such as Jurkat and huT78. We provide evidence for the involvement of the mitochondrial apoptotic pathway and observed cleavage and fragments of known caspase targets such as myosin, spectrin, and vimentin. Our findings suggest an involvement of ERM proteins, which were up-regulated and phosphorylated upon Bcl11b down-regulation. Moreover, the levels of several proteins implicated in cell cycle entry, including DUT-N, CDK6, MCM4, MCM6, and MAT1 were elevated. Thus, the proteome data presented here confirm previous findings concerning the consequences of BCL11B knock-down and provide new insight into the mechanisms of cell death and cell cycle disturbances induced by Bcl11b depletion.

Increased expression of bcl11b leads to chemoresistance accompanied by G1 accumulation

Background

The expression of BCL11B was reported in T-cells, neurons and keratinocytes. Aberrations of BCL11B locus leading to abnormal gene transcription were identified in human hematological disorders and corresponding animal models. Recently, the elevated levels of Bcl11b protein have been described in a subset of squameous cell carcinoma cases. Despite the rapidly accumulating knowledge concerning Bcl11b biology, the contribution of this protein to normal or transformed cell homeostasis remains open.

Methodology/Principal Findings

Here, by employing an overexpression strategy we revealed formerly unidentified features of Bcl11b. Two different T-cell lines were forced to express BCL11B at levels similar to those observed in primary T-cell leukemias. This resulted in markedly increased resistance to radiomimetic drugs while no influence on death-receptor apoptotic pathway was observed. Apoptosis resistance triggered by BCL11B overexpression was accompanied by a cell cycle delay caused by accumulation of cells at G1. This cell cycle restriction was associated with upregulation of CDKN1C (p57) and CDKN2C (p18) cyclin dependent kinase inhibitors. Moreover, p27 and p130 proteins accumulated and the SKP2 gene encoding a protein of the ubiquitin-binding complex responsible for their degradation was repressed. Furthermore, the expression of the MYCN oncogene was silenced which resulted in significant depletion of the protein in cells expressing high BCL11B levels. Both cell cycle restriction and resistance to DNA-damage-induced apoptosis coincided and required the histone deacetylase binding N-terminal domain of Bcl11b. The sensitivity to genotoxic stress could be restored by the histone deacetylase inhibitor trichostatine A.

Conclusions

The data presented here suggest a potential role of BCL11B in tumor survival and encourage developing Bcl11b-inhibitory approaches as a potential tool to specifically target chemoresistant tumor cells.