Transducin-like Enhancer Of Split 3 Research Articles

TLE3 Is a Novel Fusion Partner of JAK2 in Myeloid/Lymphoid Neoplasm With Eosinophilia Responding to JAK2 Inhibition.

Chromosomal rearrangements involving Janus kinase 2 (JAK2) are rare but recurrent findings in lymphoid or myeloid neoplasia. Detection of JAK2 fusion genes is important as patients with aberrantly activated JAK2 may benefit from treatment with tyrosine kinase inhibitors such as ruxolitinib. Here, we report a novel fusion gene between the transcriptional co-repressor-encoding gene transducin-like enhancer of split 3 (TLE3) and JAK2 in a patient initially diagnosed with chronic eosinophilic leukemia with additional mutations in PTPN11 and NRAS. The patient was successfully treated with the JAK2 inhibitor ruxolitinib for 8 months before additional somatic mutations were acquired and the disease progressed into an acute lymphoblastic T-cell leukemia/lymphoma. The present case shows similarities to previously reported cases with PCM1::JAK2 and BCR::JAK2 with regard to disease phenotype and response to ruxolitinib, and importantly, provides an example that also patients harboring other JAK2 fusion genes may benefit from treatment with JAK2 inhibitors.

The impact of canonical Wnt transcriptional repressors TLE3 and TLE4 on postsynaptic transcription at the neuromuscular junction.

Here, we investigated the role of the canonical Wnt signaling pathway transcriptional regulators at the neuromuscular junction. Upon applying a denervation paradigm, the transcription levels of Ctnnb1, Tcf7l1, Tle1, Tle2, Tle3, and Tle4 were significantly downregulated. A significant decrease in canonical Wnt signaling activity was observed using the denervation paradigm in Axin2-lacZ reporter mice. Alterations in the transcriptional profile of the myogenic lineage in response to agrin (AGRN) suggested that TLE3 and TLE4, family members of groucho transducin-like enhancer of split 3 (TLE3), transcriptional repressors known to antagonize T cell factor/lymphoid enhancer factor (TCF)-mediated target gene activation, could be important regulators of canonical Wnt signaling activity at the postsynapse. Knockouts of these genes using CRISPR/Cas9 gene editing in primary skeletal muscle stem cells, called satellite cells, led to decreased AGRN-dependent acetylcholine receptor (CHRN) clustering and reduced synaptic gene transcription upon differentiation of these cells. Overall, our findings demonstrate that TLE3 and TLE4 participate in diminishing canonical Wnt signaling activity, supporting transcription of synaptic genes and CHRN clustering at the neuromuscular junction.

Sulfation of chondroitin and bile acids converges to antagonize Wnt/β-catenin signaling and inhibit APC deficiency-induced gut tumorigenesis

Sulfation is a crucial and prevalent conjugation reaction involved in cellular processes and mammalian physiology. 3′-Phosphoadenosine 5′-phosphosulfate (PAPS) synthase 2 (PAPSS2) is the primary enzyme to generate the universal sulfonate donor PAPS. The involvement of PAPSS2-mediated sulfation in adenomatous polyposis coli (APC) mutation-promoted colonic carcinogenesis has not been reported. Here, we showed that the expression of PAPSS2 was decreased in human colon tumors along with cancer stages, and the lower expression of PAPSS2 was correlated with poor prognosis in advanced colon cancer. Gut epithelial-specific heterozygous Apc deficient and Papss2-knockout (ApcΔgut-HetPapss2Δgut) mice were created, and the phenotypes were compared to the spontaneous intestinal tumorigenesis of ApcΔgut-Het mice. ApcΔgut-HetPapss2Δgut mice were more sensitive to gut tumorigenesis, which was mechanistically accounted for by the activation of Wnt/β-catenin signaling pathway due to the suppression of chondroitin sulfation and inhibition of the farnesoid X receptor (FXR)-transducin-like enhancer of split 3 (TLE3) gene regulatory axis. Chondroitin sulfate supplementation in ApcΔgut-HetPapss2Δgut mice alleviated intestinal tumorigenesis. In summary, we have uncovered the protective role of PAPSS2-mediated chondroitin sulfation and bile acids–FXR–TLE3 activation in the prevention of gut carcinogenesis via the antagonization of Wnt/β-catenin signaling. Chondroitin sulfate may be explored as a therapeutic agent for Papss2 deficiency-associated colonic carcinogenesis.

HHEX suppresses advanced thyroid cancer by interacting with TLE3

Haematopoietically Expressed Homeobox (HHEX) gene is highly expressed in the thyroid gland and plays critical roles in the development and differentiation of the thyroid gland. While it has been indicated to be downregulated in thyroid cancer, its function and the underlying mechanism remain unclear. Herein, we observed low expression and aberrant cytoplasmic localization of HHEX in thyroid cancer cell lines. Knockdown of HHEX significantly enhanced cell proliferation, migration and invasion, while overexpression of HHEX showed the opposite effects in vitro and in vivo. These data provide evidence that HHEX is a tumor suppressor in thyroid cancer. Additionally, our results showed that HHEX overexpression upregulated the expression of sodium iodine symporter (NIS) mRNA and also enhanced NIS promoter activity, suggesting a favorable effect of HHEX in promoting thyroid cancer differentiation. Mechanistically, HHEX exerted a regulatory effect on the expression of transducin-like enhancer of split 3 (TLE3) protein, which inhibited the Wnt/β-catenin signaling pathway. Nuclear localized HHEX bound to and upregulated TLE3 expression by preventing TLE3 protein from being distributed to the cytoplasm and being ubiquitinated. In conclusion, our study suggested that restoring HHEX expression has the potential to be a new strategy in the treatment of advanced thyroid cancer.

Pan-Cancer Analysis of TLE3 Revealed Its Value in Tumor Microenvironment and Prognosis.

Transducin-like enhancer of split 3 (TLE3), a member of the TLE gene family, is related to tumor genesis and progression. However, whether TLE3 played a crucial role in the whole pan-cancer remained unknown. Comprehensive analysis of TCGA, GEO, and GTEx data with an online tool, and R language was performed to explore the relationship of TLE3 expression between prognosis, gene mutation, protein phosphorylation, DNA methylation, tumor microenvironment, and related pathways in 33 tumors. TLE3 was high-expressed in most tumors, and TLE3 expression and the prognosis of some tumor types were significantly correlated. The level of TLE3 expression in 33 cancer types was closely associated with DNA methylation. High-level phosphorylation sites of Tle3, such as S267 and S217, may promote cancers. In terms of the tumor microenvironment, TLE3 affected a wide variety of cancers, especially PRAD and LIHC, and TLE3 may act on them via immune-related pathways. The current work provided the first comprehensive investigation of TLE3 in a pan-cancer study, highlighting the role of TLE3 in the tumor immune microenvironment, and also determined the potential of TLE3 as a prognostic, immunotherapy response, and diagnostic biomarker in many cancers. However, the present results were preliminary and required further validation as this study was based on bioinformatics analyses.

Retraction Note: TLE3 represses colorectal cancer proliferation by inhibiting MAPK and AKT signaling pathways

Transducin-like enhancer of Split3 (TLE3) serves as a transcriptional corepressor during cell differentiation and shows multiple roles in different kinds of cancers. Recently, TLE3 together with many other genes involved in Wnt/β-catenin pathway were detected hyper-methylated in colorectal cancer (CRC). However, the potential role and the underlying mechanism of TLE3 in CRC progression remain scarce. Gene expression profiles were analyzed in The Cancer Genome Atlas (TCGA) microarray dataset of 41 normal colorectal intestine tissues and 465 CRC tissues. Western blot and Real-time Quantitative PCR (RT-qPCR) were respectively performed to detect protein and mRNA expression in 8 pairs of CRC tissue and matched adjacent normal mucosa. Immunohistochemistry (IHC) was conducted to evaluate TLE3 protein expression in 105 paraffin-embedded, archived human CRC tissues from patients, whose survival data were analyzed with Kaplan-Meier method. In vitro experiments including MTT assay, colony formation assay, and soft agar formation assay were used to investigate the effects of TLE3 on CRC cell growth and proliferation. Additionally, subcutaneous tumorigenesis assay was performed in nude mice to confirm the effects of TLE3 in vivo. Furthermore, gene set enrichment analysis (GSEA) was run to explore potential mechanism of TLE3 in CRC, and then we measured the distribution of CRC cell cycle phases and apoptosis by flow cytometry, as well as the impacts of TLE3 on MAPK and AKT signaling pathways by Western blot and RT-qPCR. TLE3 was significantly down-regulated in 465 CRC tissues compared with 41 normal tissues. Both protein and mRNA expressions of TLE3 were down-regulated in CRC compared with matched adjacent normal mucosa. Lower expression of TLE3 was significantly associated with poorer survival of patients with CRC. Besides, knock down of TLE3 promoted CRC cell growth and proliferation, while overexpression of TLE3 showed suppressive effects. Furthermore, overexpression of TLE3 caused G1-S phase transition arrest, inhibition of MAPK and AKT pathways, and up-regulation of p21Cip1/WAF1 and p27Kip1. This study indicated that TLE3 repressed CRC proliferation partly through inhibition of MAPK and AKT signaling pathways, suggesting the possibility of TLE3 as a biomarker for CRC prognosis.

Targeting of TLE3 by miR-3677 in human breast cancer promotes cell proliferation, migration and invasion.

Numerous studies have indicated an important function of microRNAs (miRs) in breast cancer (BC) progression, oncogenesis and metastasis. However, the function of miR-3677, which has been revealed to be upregulated in BC [The Cancer Genome Atlas (TCGA) data], has not been investigated to date. In the present study, miR-3677 was revealed to be upregulated in BC as determined using TCGA. miR-3677 was significantly upregulated in BC tissues and cell lines compared with those noted in adjacent non-cancerous tissues and primary normal breast cells (P<0.05). The overexpression of miR-3677 promoted the cell proliferation, migration and invasion of BC cells. Using bioinformatics algorithms and luciferase assays, a novel target gene for miR-3677, namely transducin-like enhancer of Split3 (TLE3), was identified. Silencing of TLE3 in miR-3677-transfected BC cells suppressed their proliferation and migration. An inverse correlation was observed between miR-3677 and TLE3 expression levels in human BC tissues. In conclusion, the present study demonstrated that miR-3677 promoted BC cell proliferation, migration and invasion by inhibiting TLE3 expression, which provided a novel mechanism and a promising therapeutic target for patients with BC.

Loss of TLE3 promotes the mitochondrial program in beige adipocytes and improves glucose metabolism.

Prolonged cold exposure stimulates the recruitment of beige adipocytes within white adipose tissue. Beige adipocytes depend on mitochondrial oxidative phosphorylation to drive thermogenesis. The transcriptional mechanisms that promote remodeling in adipose tissue during the cold are not well understood. Here we demonstrate that the transcriptional coregulator transducin-like enhancer of split 3 (TLE3) inhibits mitochondrial gene expression in beige adipocytes. Conditional deletion of TLE3 in adipocytes promotes mitochondrial oxidative metabolism and increases energy expenditure, thereby improving glucose control. Using chromatin immunoprecipitation and deep sequencing, we found that TLE3 occupies distal enhancers in proximity to nuclear-encoded mitochondrial genes and that many of these binding sites are also enriched for early B-cell factor (EBF) transcription factors. TLE3 interacts with EBF2 and blocks its ability to promote the thermogenic transcriptional program. Collectively, these studies demonstrate that TLE3 regulates thermogenic gene expression in beige adipocytes through inhibition of EBF2 transcriptional activity. Inhibition of TLE3 may provide a novel therapeutic approach for obesity and diabetes.

Transducin-Like Enhancer of Split 3 (TLE3) Expression Is Associated with Taxane Sensitivity in Nonserous Ovarian Carcinoma in a Three-Cohort Study.

Background: Chemoresistance is a major challenge in ovarian cancer treatment, resulting in poor survival rates. Identifying markers of treatment response is imperative for improving outcome while minimizing unnecessary side effects. We have previously demonstrated that expression of transducin-like enhancer of split 3 (TLE3) is associated with favorable progression-free survival in taxane-treated ovarian cancer patients with nonserous histology. The purpose of this study was to perform an independent evaluation of the association of TLE3 expression with response to taxane-based chemotherapy in nonserous ovarian cancer, to validate its role as a potential therapeutic response marker for taxane-based chemotherapy.Methods: We performed immunohistochemical staining of TLE3 on ovarian cancer specimens from the Australian Ovarian Cancer Study, the Westmead Gynaecological Oncology Biobank, and Memorial Sloan Kettering Cancer Center. Progression-free survival and overall survival were assessed to validate an association between TLE3 expression and response to taxane therapy that we previously observed in a smaller study.Results: Expression of TLE3 was associated with favorable outcome only in patients who had received paclitaxel as part of their treatment regimen for both 3-year progression-free survival (n = 160; HR, 0.56; P = 0.03) and 5-year overall survival (HR, 0.53; P = 0.04). Further analysis revealed that the predictive association between TLE3 expression and outcome was strongest in tumors with clear cell histology.Conclusions: The association between high TLE3 expression and a favorable response to taxane-containing chemotherapy regimens was validated in patients with nonserous ovarian cancer.Impact: TLE3 expression may serve as a marker of chemosensitivity in taxane-treated patients with nonserous histologies. Cancer Epidemiol Biomarkers Prev; 27(6); 680-8. ©2018 AACR.

RNF6 Promotes Colorectal Cancer by Activating the Wnt/β-Catenin Pathway via Ubiquitination of TLE3.

Gene amplification is a hallmark of cancer and is frequently observed in colorectal cancer. Previous whole-genome sequencing of colorectal cancer clinical specimens identified amplification of Ring finger protein 6 (RNF6), a RING-domain E3 ubiquitin ligase. In this study, we showed that RNF6 is upregulated in 73.5% (147/200) of patients with colorectal cancer and was positively associated with RNF6 gene amplification. Furthermore, RNF6 expression and its gene amplification were independent prognostic factors for poor outcome of patients with colorectal cancer. RNF6 promoted cell growth, cell-cycle progression, and epithelial-to-mesenchymal transition in colorectal cancer cells; RNF6 also promoted colorectal tumor growth and lung metastasis in mouse models. Mechanistic investigations revealed that RNF6 bound and ubiquitylated transducin-like enhancer of split 3 (TLE3), a transcriptional repressor of the β-catenin/TCF4 complex. RNF6-mediated degradation of TLE3 significantly suppressed the association of TLE3 with TCF4/LEF, which in turn led to recruitment of β-catenin to TCF4/LEF, triggering Wnt/β-catenin activation. Restoration of TLE3 expression abolished the oncogenic effects of RNF6. Taken together, these results demonstrate that RNF6 plays a pivotal oncogenic role in colorectal tumorigenesis.Significance: RNF6-mediated ubiquitination and degradation of TLE3 activates the Wnt/β-catenin pathway in colorectal carcinogenesis. Cancer Res; 78(8); 1958-71. ©2018 AACR.

Generation of a TLE3 heterozygous knockout human embryonic stem cell line using CRISPR-Cas9

Here, we generated a monoallelic mutation in the TLE3 (Transducin Like Enhancer of Split 3) gene using CRISPR-Cas9 editing in the human embryonic stem cell (hESC) line WA01. The heterozygous knockout cell line, TLE3-447-D08-A01, displays partial loss of TLE3 protein expression while maintaining pluripotency, differentiation potential and genomic integrity.

Taxane sensitivity markers in prostate cancer.

285 Background: The results from the CHAARTED and STAMPEDE trials that docetaxel plus androgen-deprivation therapy (ADT) significantly improves survival over ADT alone among men with metastatic, hormone-sensitive and hormone-naïve prostate cancers, represents a potential practice-changing movement. Clinical data exist to support the role of various predictive markers for taxane response, including low or negative class III beta tubulin (TUBB3), positive transducin-like enhancer of split 3 (TLE3) and low or negative p-glycoprotein (PGP/ABCB1). We examined a database of molecularly-profiled prostate cancer patients for taxane sensitivity markers for insight into the mechanism behind the clinical effect of docetaxel. Methods: 348 patients with prostate cancer were included in the study and tested centrally at a CLIA laboratory (Caris Life Sciences, Phoenix, AZ). Tests included one or more of the following: gene sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]) and gene amplification (C/FISH). Results: In all prostate cases tested, protein levels for taxane markers are: TLE3+ 58.6% (174/297), TUBB3 - 76.8% (228/297) and PGP – 89.9% (267/297). Combined rate of expression (TLE3+/TUBB3-/PGP-) is 41% (121/297), representing a subgroup of patients that may have best responses to taxane therapy. Taxane sensitivity markers by stage and AR status are shown in the table below. Conclusions: Taxane sensitivity markers are observed at a statistically significant higher frequency in AR-positive prostate cancer patients, providing a potential molecular hypothesis for the increased effectiveness of chemo-hormonal therapy observed in hormone-sensitive prostate cancers. A substantial number of both AR positive and negative patients have sub-optimal biomarker profile for taxane responsiveness highlighting an unmet need for on-going drug development in this disease. [Table: see text]

Cell Fate and Differentiation of Bone Marrow Mesenchymal Stem Cells.

Osteoblasts and bone marrow adipocytes originate from bone marrow mesenchymal stem cells (BMMSCs) and there appears to be a reciprocal relationship between adipogenesis and osteoblastogenesis. Alterations in the balance between adipogenesis and osteoblastogenesis in BMMSCs wherein adipogenesis is increased relative to osteoblastogenesis are associated with decreased bone quality and quantity. Several proteins have been reported to regulate this reciprocal relationship but the exact nature of the signals regulating the balance between osteoblast and adipocyte formation within the bone marrow space remains to be determined. In this review, we focus on the role of Transducin-Like Enhancer of Split 3 (TLE3), which was recently reported to regulate the balance between osteoblast and adipocyte formation from BMMSCs. We also discuss evidence implicating canonical Wnt signalling, which plays important roles in both adipogenesis and osteoblastogenesis, in regulating TLE3 expression. Currently, there is demand for new effective therapies that target the stimulation of osteoblast differentiation to enhance bone formation. We speculate that reducing TLE3 expression or activity in BMMSCs could be a useful approach towards increasing osteoblast numbers and reducing adipogenesis in the bone marrow environment.

MiR-744 increases tumorigenicity of pancreatic cancer by activating Wnt/β-catenin pathway.

The Wnt/β-catenin signaling pathway, commonly hyperactivated in pancreatic cancer, has been reported to play an important role in the maintenance of stemness of cancer stem cells (CSCs), which is closely related to the progression of pancreatic cancer. Therefore, exploring the regulatory mechanism in Wnt/β-catenin signaling may provide valuable clinical targets for cancer therapy. In the current study, we demonstrated that upregulation of miR-744 in pancreatic cancer promoted Wnt/β-catenin signaling by directly targeting secreted frizzled-related protein 1 (SFRP1), glycogen synthase kinase 3β (GSK3β), and transducin-like enhancer of split 3 (TLE3), important negative modulators of Wnt/β-catenin signaling. Expression of miR-744 was markedly upregulated in pancreatic cancer and positively correlated with poor patient survival. Furthermore, we found that overexpressing miR-744 enhanced, while inhibiting miR-744 reduced, the stem cell-like phenotype of pancreatic cancer cells in vitro. Importantly, in vivo model of human-derived pancreatic xenografts showed that miR-744 upregulation enhanced the tumorigenicity of pancreatic cancer cells. These findings suggest that miR-744 plays a vital role in promoting the stem cell-like phenotype of pancreatic cancer cells, and may represent a novel prognostic biomarker and therapeutic target.

Topoisomerase II alpha and TLE3 as predictive markers of response to anthracycline and taxane-containing regimens for neoadjuvant chemotherapy in breast cancer.

PurposeAnthracyclines and taxanes are considered the standard for neoadjuvant chemotherapy of breast cancer, although they are often associated with serious side effects and wide variability of individual response. In this study, we analyzed the value of topoisomerase II alpha (TOP2A) and transducin-like enhancer of split 3 (TLE3) as predictive markers of response to therapy with anthracyclines and taxanes.Materials and methodsTOP2A and TLE3 protein expressions were evaluated using immunohistochemistry on 28 samples, obtained by core needle biopsy in patients with locally advanced breast carcinoma, subsequently subjected to epirubicin- and paclitaxel-based neoadjuvant chemotherapy. The immunohistochemical staining was correlated with the clinical response measured by the tumor size reduction evaluated by breast magnetic resonance imaging, prior and after chemotherapy, and by pathologic evaluation of the surgical specimen.ResultsNeoadjuvant chemotherapy achieved a size reduction in 26/28 tumors (92.9%), with an average percentage decrease of 45.6%. A downstaging was achieved in 71.4% of the cases of locally advanced carcinoma. TOP2A positivity was correlated with a greater reduction in tumor diameter (P=0.06); negative staining for TLE3 was predictive of a better response to neoadjuvant chemotherapy (P=0.07). A higher reduction in tumor diameter (P=0.03) was also found for tumors that were concurrently TLE3-negative and TOP2A-positive.ConclusionTOP2A and TLE3 showed a correlation with response to neoadjuvant chemotherapy. While TOP2A is a well-known marker of response to anthracyclines-based chemotherapy, TLE3 is a new putative predictor of response to taxanes. Data from the current study suggest that TOP2A and TLE3 warrant further investigation in a larger series as predictors of response to neoadjuvant chemotherapy for locally advanced breast carcinoma.

Transducin-like enhancer of split 3 (TLE3) in adipose tissue is increased in situations characterized by decreased PPARγ gene expression.

Transgenic overexpression of adipose tissue (AT) transducin-like enhancer of split 3 (TLE3) mimicked peroxisome proliferator-activated receptor gamma (PPARγ) agonists, improving insulin resistance in mice. This study aimed to investigate TLE3 gene expression (qRT-PCR) and protein (Western blot) in subjects with a wide spectrum of obesity and insulin sensitivity and in an independent cohort of obese subjects following surgery-induced weight loss. TLE3 was analyzed in human adipocytes and after treatment with rosiglitazone. Given the findings in humans, TLE3 was also investigated in mice after a high-fat diet (HFD) and in PPARγ knockout mice. Subcutaneous (SC) AT TLE3 was increased in subjects with type 2 diabetes (T2D). In fact, SC TLE3 was associated with increased fasting glucose (r = 0.25, p = 0.015) and S6K1 activity (r = 0.671, p = 0.003), and with decreased Glut4 (r = -0.426, p = 0.006) and IRS-1 expression (-31 %, p = 0.007) and activation (P-IRS-1/IRS-1, -17 %, p = 0.024). TLE3 was preferentially expressed in mature adipocytes and increased during in vitro differentiation in parallel to PPARγ. Weight loss led to improved insulin sensitivity, increased AT PPARγ and decreased TLE3 (-24 %, p = 0.0002), while rosiglitazone administration downregulated TLE3 gene expression in fully differentiated adipocytes (-45 %, p < 0.0001). The concept that TLE3 may act as a homeostatic linchpin in AT was also supported by its increased expression in HFD-fed mice (39 %, p = 0.013) and PPARγ knockout (74 %, p = 0.001). In summary, increased AT TLE3 in subjects with T2D and in AT from HFD-fed and PPARγ knockout mice suggest that TLE3 may play an adaptive regulatory role that improves AT function under decreased PPARγ expression. TLE3 is expressed in mature adipocytes concomitantly with PPARγ. Subcutaneous adipose TLE3 is increased in T2D patients. Adipose TLE3 is upregulated in genetically ablated PPARγ and HFD-fed mice. TLE3 may be a homeostatic linchpin in insulin resistance and defective PPARγ.

TLE3, transducing-like enhancer of split 3, suppresses osteoblast differentiation of bone marrow stromal cells

In senile osteoporosis the balance of adipogenesis and osteoblastogenesis in bone marrow stromal cells (BMSCs) is disrupted so that adipogenesis is increased with respect to osteoblastogenesis, and as a result, bone mass is decreased. While the molecular mechanisms controlling the balance between osteoblastogenesis and adipogenesis are of great interest, the exact nature of the signals regulating this process remains to be determined.In general, adipogenesis is a reciprocal relationship with osteoblastogenesis in BMSCs. Recently transducin-like enhancer of split 3 (TLE3), was reported to enhance adipogenesis in pre adipocytes. However, the effect of TLE3 on osteoblast differentiation of BMSCs is completely unknown. Here we report that TLE3 not only enhances adipocyte differentiation in BMSCs but also suppresses osteoblast differentiation.Firstly we examined the expression and localization of TLE3. We found that TLE3 is expressed in the nucleus of bone marrow stromal cells and that over-expression of TLE3 induced adipocyte differentiation and suppressed ALP activity induced by treatment with BMP2 in these cells. In contrast, adipocyte differentiation was decreased and ALP activity increased when endogenous TLE3 was knocked down by shRNA in BMSCs. To examine the mechanism by which TLE3 is able to suppress osteoblast differentiation, we focused on Runx2, a transcription factor essential for osteoblast differentiation. We found that TLE3 strongly suppressed ALP activity and OSE2-luciferase activity induced by Runx2 and this repression of Runx2 by TLE3 occurs via HDACs because treatment with TSA, a class I and II HDAC inhibitor, rescued this repression.In conclusion, we identify TLE3 as a suppressor of BMSC differentiation in osteoblast lineage cells in vitro. Our data suggest that TLE3 activity may be a key in balancing adipocyte and osteoblast differentiation in the adult bone marrow microenvironment.

Frequency of TLE3 overexpression in breast carcinoma subtypes including a large cohort of triple-negative patients.

1040 Background: The taxanes are an important class of agents for the treatment of a broad range of malignancies including breast cancer. They improve survival in patients with early stage and metastatic breast cancer. Transducin-like enhancer of split 3 (TLE3) is a transcriptional repressor which influences growth and microtubule stability and its expression has been implicated in response to taxane therapy in breast cancer. We investigated the tumor expression of TLE3 in breast cancer patients, including a large cohort of the triple negative subtype. Methods: We analyzed TLE3 (M-201), ER(1D5), PR(PgR636) and HER2/neu(Polyclonal) expression by immunohistochemistry in 978 breast cancer patients. Immunoreactivity was assessed by scoring the percentage of cells stained in each field and by the intensity of staining. Results: To sub-classify the 978 breast cancer patients, we utilized hormone receptors (ER and PR) and HER2 expression/amplification. Overall, 36% of the total breast cancer patients were hormone receptor positive, 15% were HER2 positive and 49% were triple negative. The percentage of triple negative patients was higher in our cohort, given the fact that molecular profiling services are used more frequently for this subtype. A total of 477 patients were triple negative of which 61% stained positive for TLE3 expression. Of the 150 HER2 positive patients, 73% stained positive for TLE3 expression as compared with 82% TLE3 positivity in the 351 hormone receptor positive patients. By pairwise comparison, the hormone receptor positive vs triple-negative subtype showed the highest statistical significance in ratios of TLE3 positives (p =2.5e-10). Conclusions: Our results show that TLE3 is over-expressed in the majority of HER2 positive and hormone receptor positive breast cancer patients. Interestingly, the frequency of over-expression of TLE3 was lowest in the triple negative subtype thereby making it more important to identify those patients in this group who are most likely to respond to taxanes prior to therapy. To our knowledge, this is the first study providing a comprehensive review of TLE expression in breast cancer subtypes.

TLE3 Expression Is Associated with Sensitivity to Taxane Treatment in Ovarian Carcinoma

We have previously shown that transducin-like enhancer of split 3 (TLE3) is associated with outcome specifically in patients with taxane-treated breast cancer and not in patients treated with anthracycline-based regimens without a taxane. The purpose of this study was to assess the association between TLE3 expression and recurrence in patients with ovarian carcinoma treated with a taxane containing regimen as opposed to those treated with a platinum-based agent alone. We carried out immunohistochemical staining of TLE3 in two series of ovarian cancer specimens from the University of Alabama at Birmingham, Birmingham, AL and the Royal Hospital for Women, Sydney, Australia. Local and distant recurrences within the first five years of follow-up were analyzed using Kaplan-Meier, Cox proportional hazard, and multivariate analysis to assess an association between TLE3 expression and response to therapy. TLE3 was expressed in approximately 30% of tumors and expression was associated with a favorable outcome only in patients who had received taxane as part of their treatment regimen (n = 173, HR = 0.62, P = 0.012; P(interaction) = 0.024). Further analysis revealed that the predictive association between TLE3 expression and outcome was strongest in patients with nonserous histology. High TLE3 expression predicts a favorable response to taxane containing chemotherapy regimens in ovarian carcinoma. Our findings warrant an independent evaluation of TLE3 as a potential therapeutic response marker for taxane-based chemotherapy in ovarian cancer.

Highlights of This Issue

Rare genetic variants could explain common disease if they are coupled with more common single-nucleotide peptide alleles, creating “synthetic” associations. To address this possibility, Dudbridge and colleagues analyzed 10 loci that have been consistently associated with breast cancer and estimated their allele frequencies and relative risk. Using Bayesian estimation, the authors infer that these causal variants are probably common, supporting the common disease–common variant hypothesis for these loci. Current efforts to resequence these causal variant regions will help validate these quantitative estimates.The expression of transducin-like enhancer of split 3 (TLE3) was shown to be associated with favorable outcomes in taxane-treated breast cancer patients. In this study, Samimi and colleagues looked at the association of TLE3 and recurrence in ovarian carcinoma patients treated with a taxane. TLE3 immunohistochemistry was performed on ovarian cancer specimens, and disease recurrence was monitored for 5 years. The authors report that TLE3 expression was associated with favorable outcome, but only in patients who had received a taxane as part of their treatment. These results encourage further evaluation of TLE3 as a potential therapeutic response marker for taxane-based chemotherapy in ovarian cancer.Use of the diabetes drug metformin has been linked to decreased risk of some cancers, but the association of metformin and colorectal cancer remains unclear. To explore this question, Bodmer and colleagues performed a case–control analysis using the UK General Practice Research Database. The authors report that extensive use of metformin in diabetic men was associated with a slightly increased risk of colorectal cancer, compared with the risk in men who did not use metformin. Extensive use of 2 other drugs for diabetes (sulfonylurea and insulin) was not associated with an increased risk of colorectal cancer. These results indicate that metformin is not associated with a decreased risk of colorectal cancer.The costs to prepare, store, and mail sera are high and not practical in many field environments with limited resources. The use of dried blood spot (DBS) biospecimens instead of sera could reduce costs, but the reliability of DBS is uncertain. To address this question, Waterboer and colleagues compared antibody reactivities of sera and DBS from the same donors. They report that quantitative antibody reactivities in DBS and serum were correlated with both high- and low-titer antibodies. The results of this study indicate that DBS can provide a reliable alternative to serum for the detection of antibodies against various pathogens.