Deletion of leucine zipper tumor suppressor 2 (Lzts2) increases susceptibility to tumor development

Phosphorylation of LZTS2 by PLK1 activates the Wnt pathway

Lung adenocarcinoma (LUAD), responsible for nearly half of lung cancer cases, is one of the most prevalent and lethal malignant tumors globally. There is increasing evidence suggesting that the oncoprotein PLK1 plays a role in the onset and advancement of different types of cancer, including LUAD. Nonetheless, the precise mechanism by which PLK1 promotes tumorigenesis remains unclear. In this study, we demonstrate the upregulation of PLK1 in LUAD samples, which leads to a poor prognosis for LUAD patients. Intriguingly, PLK1 enables to bind to LZTS2 and promote its phosphorylation without affecting LZTS2 degradation. Furthermore, we identify that Ser451 is a key phosphorylation site in LZTS2 protein. LZTS2 exerts an anti-tumor effect by restricting the translocation of the transcription factor β-Catenin into the nucleus, thereby suppressing the Wnt pathway. PLK1 disrupts the interaction between LZTS2 and β-Catenin, resulting in the nuclear accumulation of β-Catenin and the activation of the Wnt pathway. Additionally, we reveal that LZTS2 inhibits the proliferation and migration of LUAD cells, which is rescued by PLK1. Finally, PLK1 inhibitors exhibit a dose-dependent suppression of LUAD cell proliferation and migration. Collectively, this study uncovers the pro-tumorigenic mechanism of PLK1, positioning it as a promising therapeutic target for Wnt-related LUAD.

Mechanistic insights into super-enhancer-related genes as prognostic signatures in colon cancer

BACKGROUND

Colon cancer (CC) is the most frequently occurring digestive system malignancy and is associated with a dismal prognosis. While super-enhancer (SE) genes have been identified as prognostic markers in several cancers, their potential as practical prognostic markers for CC patients remains unexplored.

METHODS

We obtained super-enhancer-related genes (SERGs) from the Human Super-Enhancer Database (SEdb). Transcriptome and relevant clinical data for colon cancer (CC) were sourced from the Gene Expression Omnibus (GEO) database. Subsequently, we identified up-regulated SERGs by the Weighted Gene Co-expression Network Analysis (WGCNA). Prognostic signatures were constructed via univariate and multivariate Cox regression analysis. We then delved into the mechanisms of these predictive genes by examining immune infiltration. We also assessed differential sensitivities to chemotherapeutic drugs between high- and low-SERGs risk patients. The critical gene was further validated using external datasets and finally confirmed by qRT PCR.

RESULTS

We established a ten-gene risk score prognostic model (S100A11, LZTS2, CYP2S1, ZNF552, PSMG1, GJC1, NXN, and DCBLD2), which can effectively predict patient survival rates. This model demonstrated effective prediction capabilities in survival rates at 1, 3, and 5 years and was successfully validated using external datasets. Furthermore, we detected significant differences in immune cell infiltration between high- and low-SERGs risk groups. Notably, high-risk patients exhibited heightened sensitivity to four chemotherapeutic agents, suggesting potential benefits for precision therapy in CC patients. Finally, qRT-PCR validation revealed a significant upregulation of LZTS2 mRNA expression in CC cells.

CONCLUSION

These findings reveal that the SERGs model could effectively predict the prognosis of CC.

α-catenin mechanosensitivity as a route to cytokinesis failure through sequestration of LZTS2

Epithelial cells can become polyploid upon tissue injury, but mechanosensitive cues that trigger this state are poorly understood. Using α-catenin (α-cat) knock-out Madin Darby Canine Kidney (MDCK) cells reconstituted with wild-type and mutant forms of α-cat as a model system, we find that an established α-cat actin-binding domain unfolding mutant designed to reduce force-sensitive binding to F-actin (α-cat-H0-FABD+) can promote cytokinesis failure, particularly along epithelial wound-fronts. Enhanced α-cat coupling to cortical actin is neither sufficient nor mitotic cell-autonomous for cytokinesis failure, but critically requires the mechanosensitive Middle-domain (M1-M2-M3) and neighboring cells. Disease relevant α-cat M-domain missense mutations known to cause a form of retinal pattern dystrophy (α-cat E307K or L436P) are associated with elevated binucleation rates via cytokinesis failure. Similar binucleation rates are seen in cells expressing an α-cat salt-bridge destabilizing mutant (R551A) designed to promote M2-M3 domain unfurling at lower force thresholds. Since binucleation is strongly enhanced by removal of the M1 as opposed to M2-M3 domains, cytokinetic fidelity is most sensitive to α-cat M2-M3 domain opening. To identify α-cat conformation-dependent proximity partners that contribute to cytokinesis, we used a biotin-ligase approach to distinguished proximity partners that show enhanced recruitment upon α-cat M-domain unfurling (R551A). We identified Leucine Zipper Tumor Suppressor 2 (LZTS2), an abscission factor previously implicated in cytokinesis. We confirm that LZTS2 enriches at the midbody, but discover it also localizes to tight and tricellular junctions. LZTS2 knock-down promotes binucleation in both MDCK and Retinal Pigmented Epithelial (RPE) cells. α-cat mutants with persistent M2-M3 domain opening showed elevated junctional enrichment of LZTS2 from the cytosol compared α-cat wild-type cells. These data implicate LZTS2 as a mechanosensitive effector of α-cat that is critical for cytokinetic fidelity. This model rationalizes how persistent mechano-activation of α-cat may drive tension-induced polyploidization of epithelia post-injury and suggests an underlying mechanism for how pathogenic α-cat mutations drive macular dystrophy.

Lipidomic and Membrane Mechanical Signatures in Triple-Negative Breast Cancer: Scope for Membrane-Based Theranostics

Triple-negative breast cancer (TNBC) is a highly aggressive form of breast cancer associated with poor prognosis, higher grade, and a high rate of metastatic occurrence. Limited therapeutic interventions and the compounding issue of drug resistance in triple-negative breast cancer warrants the discovery of novel therapeutic targets and diagnostic modules. To this view, in addition to proteins, lipids also regulate cellular functions via the formation of membranes that modulate membrane protein function, diffusion, and their localization; thus, orchestrating signaling hot spots enriched in specific lipids/proteins on cell membranes. Lipid deregulation in cancer leads to reprogramming of the membrane dynamics and functions impacting cell proliferation, metabolism, and metastasis, providing exciting starting points for developing lipid-based approaches for treating TNBC. In this review, we provide a detailed account of specific lipidic changes in breast cancer, link the altered lipidome with membrane structure and mechanical properties, and describe how these are linked to subsequent downstream functions implicit in cancer progression, metastasis, and chemoresistance. At the fundamental level, we discuss how the lipid-centric findings in TNBC are providing cues for developing lipid-inspired theranostic strategies while bridging existing gaps in our understanding of the functional involvement of lipid membranes in cancer.

Long non-coding RNA linc00921 suppresses tumorigenesis and epithelial-to-mesenchymal transition of triple-negative breast cancer via targeting miR-9-5p/LZTS2 axis

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Dysregulation of long non-coding RNAs (lncRNAs) plays crucial roles in the initiation and progression of TNBC. In this study, we analyzed public GEO profiles to verify the key lncRNAs in TNBC. Linc00921 was selected for further study. Low expression of linc00921 was observed in 49 of 95 TNBC tissues. Low expression of linc00921 was correlated with poor postoperative disease-free survival (DFS) and overall survival (OS) of TNBC patients. Overexpression of linc00921 with lentivirus suppressed the proliferation, migration and invasion of TNBC cells. A luciferase reporter assay showed that linc00921 could sponge miR-9-5p in TNBC. Moreover, linc00921 and miR-9-5p occupied the same Argonaute-2 (Ago2) protein in TNBC cells. Leucine zipper tumor suppressor 2 (LZTS2) was recognized as a target gene of miR-9-5p, and thereby a linc00921/miR-9-5p/LZTS2 axis was identified in TNBC cells. Overexpression of linc00921 promoted nuclear export of β-catenin, neutralized its function, and subsequently promoted epithelial-to-mesenchymal transition (EMT) in TNBC. A xenograft tumor mouse model showed that the miR-9-5p inhibitor upregulates LZTS2 expression and induce nuclear export of β-catenin in TNBC. Thus, linc00921 upregulates LZTS2 by sponging miR-9-5p to suppress tumorigenesis and EMT of TNBC. Linc00921/miR-9-5p/LZTS2 axis may be a novel biomarker and therapeutic target for TNBC patients.

Microglia in Alzheimer's Disease: An Unprecedented Opportunity as Prospective Drug Target

Alzheimer's disease (AD) is an ever more common neurodegenerative disease among the elderly, characterized by recurrent neuroinflammation and amyloid beta (Aβ) accumulation in the brain parenchyma. Recent genome-wide association studies (GWAS) have shown a distinct role for the innate immune system in AD, with microglia playing a key role. The function of microglial cells is stringently regulated by the neighboring microenvironment in the brain. Upon interruption in diseases, like AD, it demonstrates neurotoxic and neuroprotective action by M1 (neurotoxic) and M2 (neuroprotective) microglial phenotypes, respectively, in the brain. Microglial cells on activation by complement factors, toll-like receptors, and genetic variants result in Aβ' phagocytosis, synaptic pruning, and reactivation of complement pathway. Recent studies have demonstrated the presence of potential therapeutic targets in microglial cells. Immune receptors revealed on microglia as potential drug targets can be paired immunoglobulin-like type 2 receptor (PILR), CD3358, and triggering receptor expressed on myeloid cells 2 (TREM2), as they can have impact on late-onset AD occurrence and progression. Thus, targeting these receptors can accentuate the beneficial effects of microglial cells required to decelerate the progression of AD. This review emphasizes the microglial phenotypes, its function in AD brain, and potential immunological and therapeutic targets to fight this highly progressive neurodegenerative disorder.

β-Trcp and CK1δ-mediated degradation of LZTS2 activates PI3K/AKT signaling to drive tumorigenesis and metastasis in hepatocellular carcinoma

Distant metastasis is the leading cause of treatment failure in patients with hepatocellular carcinoma (HCC). However, the underlying mechanisms have not been fully elucidated. Here, we report that Leucine zipper tumor suppressor 2 (LZTS2) is downregulated and correlated with poor prognosis in HCC. Furthermore, we provide evidence that LZTS2 associates with p85 to inhibit the activation of PI3K/AKT signaling and impairs HCC tumorigenesis and metastasis in vitro and in vivo. Moreover, we identify LZTS2 as a bona fide substrate of the E3 ligase β-Trcp and protein kinase CK1δ, which are responsible for the ubiquitination and degradation of LZTS2. Importantly, we show that the β-Trcp and CK1δ-mediated degradation of LZTS2 promotes HCC progression and metastasis by activating PI3K/AKT signaling. Collectively, our study not only illustrates the roles of LZTS2 in regulating HCC tumorigenesis and metastasis but also reveals a novel posttranslational modification of LZTS2 by β-Trcp and CK1δ, indicating that the β-Trcp/CK1δ/LZTS2/PI3K axis may be a novel oncogenic driver involved in HCC progression and metastasis.

Loss of the tumor suppressor, Tp53, enhances the androgen receptor-mediated oncogenic transformation and tumor development in the mouse prostate

Recent genome analysis of human prostate cancers demonstrated that both AR gene amplification and TP53 mutation are among the most frequently observed alterations in advanced prostate cancer. However, the biological role of these dual genetic alterations in prostate tumorigenesis is largely unknown. In addition, there are no biologically relevant models that can be used to assess the molecular mechanisms for these genetic abnormalities. Here, we report a novel mouse model, in which elevated transgenic AR expression and Trp53 deletion occur simultaneously in mouse prostatic epithelium to mimic human prostate cancer cells. These compound mice developed an earlier onset of high-grade prostatic intraepithelial neoplasia and accelerated prostate tumors in comparison to mice harboring only the AR transgene. Histological analysis showed prostatic sarcomatoid and basaloid carcinomas with massive squamous differentiation in the above compound mice. RNA-sequencing analyses identified a robust enrichment of the signature genes for human prostatic basal cell carcinomas in the above prostate tumors. Master Regulator Analysis revealed SOX2 as a transcriptional regulator in prostatic basal cell tumors. Elevated expression of SOX2 and its downstream target genes were detected in prostatic tumors of the compound mice. Chromatin immunoprecipitation analyses implicate a co-regulatory role of AR and SOX2 in the expression of prostatic basal cell signature genes. Our data demonstrate a critical role of SOX2 in prostate tumorigenesis and provide mechanistic insight into prostate tumor aggressiveness and progression mediated by aberrant AR and p53 signaling pathways.

LZTS2 promoter hypermethylation: a potential biomarker for the diagnosis and prognosis of laryngeal squamous cell carcinoma

BACKGROUND

LZTS2 (leucine zipper tumor suppressor 2), a candidate tumor suppressor gene, suppresses cell growth and plays a vital role in the carcinogenesis and development of tumors. No studies to date have described methylation of the LZTS2 promoter in human cancers, including LSCC (laryngeal squamous cell carcinoma). Therefore, the aim of this study was to explore the relationship between LZTS2 promoter methylation and risk of LSCC.

METHODS

In our study, LZTS2 promoter methylation levels in LSCC tumor and adjacent normal tissues from 96 patients were measured using quantitative methylation-specific polymerase chain reaction (qMSP) assays.

RESULTS

The qMSP analyses revealed that LZTS2 promoter methylation levels in the LSCC tumor samples were significantly higher than those in paired adjacent healthy tissue samples. Furthermore, LZTS2 methylation levels were elevated in smokers, advanced T classified, and clinically staged patients, as well as in patients with lymph node metastases. In addition, Kaplan-Meier survival curves results showed that overall survival of LSCC patients with hypomethylated LZTS2 promoters was significantly higher than that in patients with hyper-methylated LZTS2 promoters (log-rank test P = 0.028). Meanwhile, the area under the receiver operating characteristic curve was 0.920. The diagnostic threshold value for LZTS2 methylation was 11.63% (94.7% sensitivity and 80.4% specificity).

CONCLUSIONS

LZTS2 promoter hypermethylation is associated with risk, progression, and prognosis of LSCC in a cohort of 96 human subjects; LZTS2 promoter hypermethylation is a candidate diagnostic and prognostic biomarker for LSCC.

An Indispensable Role of Androgen Receptor in Wnt Responsive Cells During Prostate Development, Maturation, and Regeneration

Androgen signaling is essential for prostate development, morphogenesis, and regeneration. Emerging evidence indicates that Wnt/β-catenin signaling also contributes to prostate development specifically through regulation of cell fate determination. Prostatic Axin2-expressing cells are able to respond to Wnt signals and possess the progenitor properties to regenerate prostatic epithelium. Despite critical roles of both signaling pathways, the biological significance of androgen receptor (AR) in Axin2-expressing/Wnt-responsive cells remains largely unexplored. In this study, we investigated this important question using a series of newly generated mouse models. Deletion of Ar in embryonic Axin2-expressing cells impaired early prostate development in both ex vivo and tissue implantation experiments. When Ar expression was deleted in prostatic Axin2-expressing cells at pre-puberty stages, it results in smaller and underdeveloped prostates. A subpopulation of Axin2 expressing cells in prostate epithelium is resistant to castration and, following androgen supplementation, is capable to expand to prostatic luminal cells. Deletion of Ar in these Axin2-expressing cells reduces their regenerative ability. These lines of evidence demonstrate an indispensable role for the Ar in Wnt-responsive cells during the course of prostate development, morphogenesis, and regeneration, which also imply an underlying interaction between the androgen and Wnt signaling pathways in the mouse prostate. Stem Cells 2018;36:891-902.

LZTS2 inhibits PI3K/AKT activation and radioresistance in nasopharyngeal carcinoma by interacting with p85

Phosphoinositide 3-kinase (PI3K) activity is aberrantly activated in nasopharyngeal carcinoma. However, the underlying mechanisms remain unclear. Here, we found that Leucine zipper tumor suppressor 2 (LZTS2) was downregulated and predicted poor prognosis in nasopharyngeal carcinoma patients. Furthermore, we identified the PI3K subunit p85 as a novel LZTS2-interacting protein using an unbiased proteomics approach. Moreover, we demonstrated that LZTS2 competes with p110 for p85 binding and inhibits activation of the PI3K/AKT signaling pathway. Functionally, we showed that LZTS2 suppresses tumorigenesis and radioresistance in nasopharyngeal carcinoma in a p85-dependent manner. Taken together, our results not only provide understanding of the molecular mechanisms by which PI3K/AKT signaling is activated but also suggest that targeting the LZTS2/PI3K/AKT signaling axis is a promising therapeutic strategy for radiosensitization of nasopharyngeal carcinoma.

Admixture mapping of uterine fibroid size and number in African American women

OBJECTIVE

To evaluate the relationship between genetic ancestry and uterine fibroid characteristics.

DESIGN

Cross-sectional study.

SETTING

Not applicable.

PATIENT(S)

A total of 609 African American participants with image- or surgery-confirmed fibroids in a biorepository at Vanderbilt University electronic health record biorepository and the Coronary Artery Risk Development in Young Adults studies were included.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Outcome measures include fibroid number (single vs. multiple), volume of largest fibroid, and largest fibroid dimension of all fibroid measurements.

RESULT(S)

Global ancestry meta-analyses revealed a significant inverse association between percentage of European ancestry and risk of multiple fibroids (odds ratio: 0.78; 95% confidence interval 0.66, 0.93; P=6.05 × 10-3). Local ancestry meta-analyses revealed five suggestive (P<4.80 × 10-3) admixture mapping peaks in 2q14.3-2q21.1, 3p14.2-3p14.1, 7q32.2-7q33, 10q21.1, 14q24.2-14q24.3, for number of fibroids and one suggestive admixture mapping peak (P<1.97 × 10-3) in 10q24.1-10q24.32 for volume of largest fibroid. Single variant association meta-analyses of the strongest associated region from admixture mapping of fibroid number (10q21.1) revealed a strong association at single nucleotide polymorphism variant rs12219990 (odds ratio: 0.41; 95% confidence interval 0.28, 0.60; P=3.82 × 10-6) that was significant after correction for multiple testing.

CONCLUSION(S)

Increasing African ancestry is associated with multiple fibroids but not with fibroid size. Local ancestry analyses identified several novel genomic regions not previously associated with fibroid number and increasing volume. Future studies are needed to explore the genetic impact that ancestry plays into the development of fibroid characteristics.

LZTS2 and PTEN collaboratively regulate ß-catenin in prostatic tumorigenesis

The leucine zipper tumor suppressor 2 (LZTS2) was identified as a tumor susceptibility gene within the 10q24.3 chromosomal region, and is approximately 15Mb from the PTEN locus. This region containing the both loci is frequently deleted in a variety of human malignancies, including prostate cancer. LZTS2 is a ß-catenin-binding protein and a negative regulator of Wnt signaling. Overexpression of PTEN in prostate cancer cell lines reduces ß-catenin-mediated transcriptional activity. In this study, we examined the collaborative effect of PTEN and LZTS2 using multiple in vitro and in vivo approaches. Co-expression of PTEN and LZTS2 in prostate cancer cells shows stronger repressive effect on ß-catenin mediated transcription. Using a newly generated mouse model, we further assessed the effect of simultaneous deletion of Pten and Lzts2 in the murine prostate. We observed that mice with both Lzts2 and Pten deletion have an earlier onset of prostate carcinomas as well as an accelerated tumor progression compared to mice with Pten or Lzts2 deletion alone. Immunohistochemical analyses show that atypical and tumor cells from compound mice with both Pten and Lzts2 deletion are mainly composed of prostate luminal epithelial cells and possess higher levels of cytoplasmic and nuclear β-catenin. These cells also exhibit a higher proliferative capacity than cells isolated from single deletion mice. These data demonstrate the significance of simultaneous Pten and Lzts2 deletion in oncogenic transformation in prostate cells and implicates a new mechanism for the dysregulation of Wnt/β-catenin signaling in prostate tumorigenesis.

Prognostic methylation markers for overall survival in cytogenetically normal patients with acute myeloid leukemia treated on SWOG trials

BACKGROUND

Aberrant DNA methylation is known to occur in patients with acute myeloid leukemia (AML), whereas methylation signatures and prognostic markers have been proposed. The objective of the current study was to evaluate all CpG sites of the genome and identify prognostic methylation markers for overall survival in patients with AML with normal karyotype (AML-NK).

METHODS

AML-NK samples from 7 SWOG trials were analyzed using a novel genome-wide approach called "CHARMcox" (comprehensive high-throughput array-based relative methylation analysis combined with the Cox proportional hazards model) controlling for known clinical covariates. CHARMcox was applied to a phase 1 discovery cohort (72 patients) to identify survival-associated methylation regions (SAMRs). Subsequently, using bisulfite pyrosequencing, SAMRs were studied in phase 2 model-building (65 patients) and phase 3 validation (65 patients) cohorts. An independent external cohort from The Cancer Genome Atlas (TCGA) AML study (LAML) was used for further validation (93 patients).

RESULTS

Two SAMRs, located at the CpG island shores of leucine zipper tumor suppressor 2 (LZTS2) and nuclear receptor subfamily 6 group a member 1 (NR6A1), respectively, were identified. Multivariable analyses demonstrated that hypomethylation of either LZTS2 or NR6A1 was associated with worse overall survival in the SWOG cohort (P<.001). The prognosis was validated in patients with AML-NK from the TCGA-LAML cohort. Methylation values below the median at both markers predicted worse overall survival (SWOG: hazard ratio, 1.89 [P<.001]; and TCGA-LAML: hazard ratio, 2.08 [P=.006]). The C-statistic was 0.71 for both cohorts, and the impact was independent of the Fms-related tyrosine kinase 3 internal tandem duplication (FLT3-ITD) status.

CONCLUSIONS

The 2 methylation markers, measurable by clinically applicable assays such as bisulfite pyrosequencing, are promising for risk stratification among patients with AML-NK. Cancer 2017;123:2472-81. © 2017 American Cancer Society.

Heterogeneity in readouts of canonical wnt pathway activity within intestinal crypts

BACKGROUND

Canonical Wnt pathway signaling is necessary for maintaining the proliferative capacity of mammalian intestinal crypt base columnar stem cells (CBCs). Furthermore, dysregulation of the Wnt pathway is a major contributor to disease, including oncogenic transformation of the intestinal epithelium. Given the critical importance of this pathway, numerous tools have been used as proxy measures for Wnt pathway activity, yet the relationship between Wnt target gene expression and reporter allele activity within individual cells at the crypt base remains unclear.

RESULTS

Here, we describe a novel Axin2-CreERT2-tdTomato allele that efficiently marks both Wnt(High) CBCs and radioresistant reserve intestinal stem cells. We analyze the molecular and functional identity of Axin2-CreERT2-tdTomato-marked cells using single cell gene expression profiling and tissue regeneration assays and find that Axin2 reporter activity does not necessarily correlate with expression of Wnt target genes and, furthermore, that Wnt target genes themselves vary in their expression patterns at the crypt base.

CONCLUSIONS

Wnt target genes and reporter alleles can vary greatly in their cell-type specificity, demonstrating that these proxies cannot be used interchangeably. Furthermore, Axin2-CreERT2-tdTomato is a robust marker of both active and reserve intestinal stem cells and is thus useful for understanding the intestinal stem cell compartment. Developmental Dynamics 245:822-833, 2016. © 2016 Wiley Periodicals, Inc.

Androgen signaling is a confounding factor for β-catenin-mediated prostate tumorigenesis

Emerging evidence has demonstrated the critical roles for both androgen and Wnt pathways in prostate tumorigenesis. A recent integrative genomic analysis of human prostate cancers has revealed a unique enrichment of androgen and Wnt signaling in early onset prostate cancers, implying their clinical significance in the disease. Additionally, interaction between the androgen receptor (AR) and β-catenin has long been detected in prostate cancer cells. However, the consequence of this interaction in prostate tumorigenesis is still unknown. Because mutations in adenomatous polyposis coli (APC), β-catenin, and other components of the destruction-complex are generally rare in prostate cancers, other mechanisms of aberrant Wnt signaling activation have been speculated. To address these critical questions, we developed Ctnnb1^L(ex3)/+/R26hAR^L/+:PB-Cre4 mice, in which transgenic AR and stabilized β-catenin are co-expressed in prostatic epithelial cells. We observed accelerated tumor development, aggressive tumor invasion, and a decreased survival rate in Ctnnb1^L(ex3)/+/R26hAR^L/+:PB-Cre4 compound mice compared to age-matched Ctnnb1^L(ex3)/+:PB-Cre4 littermate controls, which only have stabilized β-catenin expression in the prostate. Castration of the above transgenic mice resulted in significant tumor regression, implying an essential role of androgen signaling in tumor growth and maintenance. Implantation of the prostatic epithelial cells isolated from the transgenic mice regenerated PIN and prostatic adenocarcinoma lesions. Microarray analyses of transcriptional profiles showed more robust enrichment of known tumor and metastasis promoting genes: Spp1, Egr1, c-Myc, Sp5, and Sp6 genes in samples isolated from Ctnnb1^L(ex3)/+/R26hAR^L/+:PB-Cre4 compound mice than those from Ctnnb1^L(ex3)/+:PB-Cre4 and R26hAR^L/+:PB-Cre4 littermate controls. Together, these data demonstrate a confounding role of androgen signaling in β-catenin initiated oncogenic transformation in prostate tumorigenesis.

Crosstalking between androgen and PI3K/AKT signaling pathways in prostate cancer cells

Both androgen action and PI3K medicated signaling pathways have been implicated in prostate tumorigenesis. Our androgen receptor (AR) conditional transgenic mice developed murine prostatic intraepithelial neoplasia (mPIN) and prostatic adenocarcinoma lesions recapitulating human prostate cancer development and progression. Role of transgenic AR contributing to malignancy was demonstrated by high degree of transgenic AR expression in atypical and tumor cells in mPIN as well as prostatic adenocarcinoma lesions of the transgenic mice, but not in adjacent normal tissue. Interestingly, reduced PI3K/Akt activation also appeared in these mouse atypical and tumor cells, suggesting an interaction between androgen and PI3K/AKT pathways. In this study, we further investigated this interaction. We showed that the androgen depletion or knockdown of AR expression results in elevated levels of active phosphorylated AKT in prostate cancer cells. Castration of conditional Pten knock-out mice showed increased Akt, phosphorylated Akt, and pS6 expression in the mouse prostate. Using a series of newly generated Ar reporter and Pten knock-out compound mice, we showed that Pten loss directly represses endogenous Ar expression in prostatic epithelial cells. Moreover, Pten loss and PI3K/Akt activation reduced Ar-mediated transcription in purified Pten-null cells. This study provides novel evidence demonstrating interplay between androgen and PI3K pathways, as well as introduces unique and relevant mouse models for further studies of PI3K and AR pathways in the context of prostate tumorigenesis.

The H3K27me3 demethylase UTX is a gender-specific tumor suppressor in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive form of leukemia that is mainly diagnosed in children and shows a skewed gender distribution toward males. In this study, we report somatic loss-of-function mutations in the X-linked histone H3K27me3 demethylase ubiquitously transcribed X (UTX) chromosome, in human T-ALL. Interestingly, UTX mutations were exclusively present in male T-ALL patients and allelic expression analysis revealed that UTX escapes X-inactivation in female T-ALL lymphoblasts and normal T cells. Notably, we demonstrate in vitro and in vivo that the H3K27me3 demethylase UTX functions as a bona fide tumor suppressor in T-ALL. Moreover, T-ALL driven by UTX inactivation exhibits collateral sensitivity to pharmacologic H3K27me3 inhibition. All together, our results show how a gender-specific and therapeutically relevant defect in balancing H3K27 methylation contributes to T-cell leukemogenesis.