DNA Damage Promotes TMPRSS2-ERG Oncoprotein Destruction and Prostate Cancer Suppression via Signaling Converged by GSK3ß and WEE1.

TMPRSS2-ERG gene fusion occurs in approximately 50% of cases of prostate cancer (PCa), and the fusion product is a key driver of prostate oncogenesis. However, how to leverage cellular signaling to ablate TMPRSS2-ERG oncoprotein for PCa treatment remains elusive. Here, we demonstrate that DNA damage induces proteasomal degradation of wild-type ERG and TMPRSS2-ERG oncoprotein through ERG threonine-187 and tyrosine-190 phosphorylation mediated by GSK3ß and WEE1, respectively. The dual phosphorylation triggers ERG recognition and degradation by the E3 ubiquitin ligase FBW7 in a manner independent of a canonical degron. DNA damage-induced TMPRSS2-ERG degradation was abolished by cancer-associated PTEN deletion or GSK3ß inactivation. Blockade of DNA damage-induced TMPRSS2-ERG oncoprotein degradation causes chemotherapy-resistant growth of fusion-positive PCa cells in culture and in mice. Our findings uncover a previously unrecognized TMPRSS2-ERG protein destruction mechanism and demonstrate that intact PTEN and GSK3ß signaling are essential for effective targeting of ERG protein by genotoxic therapeutics in fusion-positive PCa.

EZH2 cooperates with gain-of-function p53 mutants to promote cancer growth and metastasis.

In light of the increasing number of identified cancer-driven gain-of-function (GOF) mutants of p53, it is important to define a common mechanism to systematically target several mutants, rather than developing strategies tailored to inhibit each mutant individually. Here, using RNA immunoprecipitation-sequencing (RIP-seq), we identified the Polycomb-group histone methyltransferase EZH2 as a p53 mRNA-binding protein. EZH2 bound to an internal ribosome entry site (IRES) in the 5'UTR of p53 mRNA and enhanced p53 protein translation in a methyltransferase-independent manner. EZH2 augmented p53 GOF mutant-mediated cancer growth and metastasis by increasing protein levels of mutant p53. EZH2 overexpression was associated with worsened outcome selectively in patients with p53-mutated cancer. Depletion of EZH2 by antisense oligonucleotides inhibited p53 GOF mutant-mediated cancer growth. Our findings reveal a non-methyltransferase function of EZH2 that controls protein translation of p53 GOF mutants, inhibition of which causes synthetic lethality in cancer cells expressing p53 GOF mutants.

Generating real-world evidence from unstructured clinical notes to examine clinical utility of genetic tests: use case in BRCAness.

BACKGROUND: Next-generation sequencing provides comprehensive information about individuals' genetic makeup and is commonplace in oncology clinical practice. However, the utility of genetic information in the clinical decision-making process has not been examined extensively from a real-world, data-driven perspective. Through mining real-world data (RWD) from clinical notes, we could extract patients' genetic information and further associate treatment decisions with genetic information. METHODS: We proposed a real-world evidence (RWE) study framework that incorporates context-based natural language processing (NLP) methods and data quality examination before final association analysis. The framework was demonstrated in a Foundation-tested women cancer cohort (N = 196). Upon retrieval of patients' genetic information using NLP system, we assessed the completeness of genetic data captured in unstructured clinical notes according to a genetic data-model. We examined the distribution of different topics regarding BRCA1/2 throughout patients' treatment process, and then analyzed the association between BRCA1/2 mutation status and the discussion/prescription of targeted therapy. RESULTS: We identified seven topics in the clinical context of genetic mentions including: Information, Evaluation, Insurance, Order, Negative, Positive, and Variants of unknown significance. Our rule-based system achieved a precision of 0.87, recall of 0.93 and F-measure of 0.91. Our machine learning system achieved a precision of 0.901, recall of 0.899 and F-measure of 0.9 for four-topic classification and a precision of 0.833, recall of 0.823 and F-measure of 0.82 for seven-topic classification. We found in result-containing sentences, the capture of BRCA1/2 mutation information was 75%, but detailed variant information (e.g. variant types) is largely missing. Using cleaned RWD, significant associations were found between BRCA1/2 positive mutation and targeted therapies. CONCLUSIONS: In conclusion, we demonstrated a framework to generate RWE using RWD from different clinical sources. Rule-based NLP system achieved the best performance for resolving contextual variability when extracting RWD from unstructured clinical notes. Data quality issues such as incompleteness and discrepancies exist thus manual data cleaning is needed before further analysis can be performed. Finally, we were able to use cleaned RWD to evaluate the real-world utility of genetic information to initiate a prescription of targeted therapy.

Genes associated with bowel metastases in ovarian cancer.

OBJECTIVE: This study is designed to identify genes and pathways that could promote metastasis to the bowel in high-grade serous ovarian cancer (OC) and evaluate their associations with clinical outcomes. METHODS: We performed RNA sequencing of OC primary tumors (PTs) and their corresponding bowel metastases (n = 21 discovery set; n = 18 replication set). Differentially expressed genes (DEGs) were those expressed at least 2-fold higher in bowel metastases (BMets) than PTs in at least 30% of patients (P < .05) with no increased expression in paired benign bowel tissue and were validated with quantitative reverse transcription PCR. Using an independent OC cohort (n = 333), associations between DEGs in PTs and surgical and clinical outcomes were performed. Immunohistochemistry and mouse xenograft studies were performed to confirm the role of LRRC15 in promoting metastasis. RESULTS: Among 27 DEGs in the discovery set, 21 were confirmed in the replication set: SFRP2, Col11A1, LRRC15, ADAM12, ADAMTS12, MFAP5, LUM, PLPP4, FAP, POSTN, GRP, MMP11, MMP13, C1QTNF3, EPYC, DIO2, KCNA1, NETO1, NTM, MYH13, and PVALB. Higher expression of more than half of the genes in the PT was associated with an increased requirement for bowel resection at primary surgery and an inability to achieve complete cytoreduction. Increased expression of LRRC15 in BMets was confirmed by immunohistochemistry and knockdown of LRRC15 significantly inhibited tumor progression in mice. CONCLUSIONS: We identified 21 genes that are overexpressed in bowel metastases among patients with OC. Our findings will help select potential molecular targets for the prevention and treatment of malignant bowel obstruction in OC.

Uterine serous carcinoma: Reassessing effectiveness of platinum-based adjuvant therapy.

OBJECTIVE: Two randomized trials failed to demonstrate efficacy of platinum-based chemotherapy (PbCT) for uterine serous carcinoma (USC). Our objective was to reassess the value of PbCT for patients with microscopic residuum (R0). METHODS: Progression-free survival (PFS) after surgery was analyzed for 409 patients and correlated with adjuvant therapies: vaginal brachytherapy (VBRT), external beam radiotherapy (EBRT), PbCT, or combinations. RESULTS: The estimated 5-year PFS for stage I (n=209) USC was 65.1% for observation only; 90.7%, VBRT only; and 91.1%, PbCT±VBRT (85% received VBRT); VBRT significantly (P=.004) impacted PFS, but the added value of PbCT remains uncertain. Of 58 stage IIIC, PbCT-treated patients (±EBRT), 5-year PFS was 33.9%; most failures had a vascular disseminated component. Median PFS for 72 stage IV, PbCT-treated patients was 18.6months for R0; 8.0, R1≤1cm residual disease; and 4.6, R2>1cm (P=.008). The progression rate (PR) during 1 to 2year follow-up for R0 was similar to PR during 0-1year follow-up for R1 (P=.31), suggesting recurrences in patients with R0 disease before 2years are likely platinum resistant. PRs during follow-up were nearly identical for R0≥2years and R1≥1year (P=.95), presumably showing limited numbers of platinum-sensitive tumors. CONCLUSIONS: A comparison of PR for patients treated with PbCT for stage IV R0 and R1 disease suggested that a 1-year lag interval precedes clinical recognition of PbCT refractory/resistant R0 disease. Most patients treated with PbCT who had microscopic residuum had recurrences within 2years (across stages), emphasizing the need for more effective therapy.

Epigenomics may begin to explain in vitro differential response to hypomethylating agents in MMR-D hypermethylated endometrial cancer.

This work examines differences in chromatin accessibility, methylation, and response to DNA hypomethylating agents between mismatch repair-deficient and non-mismatch repair-deficient endometrial cancer. Next-generation sequencing of a stage 1B, grade 2 endometrioid endometrial cancer tumor revealed microsatellite instability and a variant of unknown significance in POLE along with global and MLH1 hypermethylation. Inhibition of viability by decitabine in the study and comparison tumors was minimal, as shown by an inhibitory effect of 0 and 17.9, respectively. Conversely, the inhibitory effect of azacitidine on the study tumor was more pronounced, at 72.8 versus 41.2. In vitro, mismatch repair-deficient endometrial cancer with MLH1 hypermethylation respond better to DNA methyltransferase inhibition by azacytidine (DNA/RNA inhibition), than to decitabine (DNA-only inhibition). Additional large studies are needed to substantiate our findings.

Retinoblastoma protein as an intrinsic BRD4 inhibitor modulates small molecule BET inhibitor sensitivity in cancer.

Bromodomain and extraterminal (BET) proteins including BRD4 play important roles in oncogenesis and immune inflammation. Here we demonstrate that cancer cells with loss of the retinoblastoma (RB) tumor suppressor became resistant to small molecule bromodomain inhibitors of BET proteins. We find that RB binds to bromodomain-1 (BD1) of BRD4, but binding is impeded by CDK4/6-mediated RB phosphorylation at serine-249/threonine-252 (S249/T252). ChIP-seq analysis shows RB knockdown increases BRD4 occupancy at genomic loci of genes enriched in cancer-related pathways including the GPCR-GNBIL-CREB axis. S249/T252-phosphorylated RB positively correlates with GNBIL protein level in prostate cancer patient samples. BET inhibitor resistance in RB-deficient cells is abolished by co-administration of CREB inhibitor. Our study identifies RB protein as a bona fide intrinsic inhibitor of BRD4 and demonstrates that RB inactivation confers resistance to small molecule BET inhibitors, thereby revealing a regulatory hub that converges RB upstream signaling onto BRD4 functions in diseases such as cancer.

Constitutive BAK/MCL1 complexes predict paclitaxel and S63845 sensitivity of ovarian cancer.

We previously found that preformed complexes of BAK with antiapoptotic BCL2 proteins predict BH3 mimetic sensitivities in lymphohematopoietic cells. These complexes have not previously been examined in solid tumors or in the context of conventional anticancer drugs. Here we show the relative amount of BAK found in preformed complexes with MCL1 or BCLXL varies across ovarian cancer cell lines and patient-derived xenografts (PDXs). Cells bearing BAK/MCL1 complexes were more sensitive to paclitaxel and the MCL1 antagonist S63845. Likewise, PDX models with BAK/MCL1 complexes were more likely to respond to paclitaxel. Mechanistically, BIM induced by low paclitaxel concentrations interacted preferentially with MCL1 and displaced MCL1-bound BAK. Further studies indicated that cells with preformed BAK/MCL1 complexes were sensitive to the paclitaxel/S63845 combination, while cells without BAK/MCL1 complexes were not. Our study suggested that the assessment of BAK/MCL1 complexes might be useful for predicting response to paclitaxel alone or in combination with BH3 mimetics.

SPOP mutation induces DNA methylation via stabilizing GLP/G9a.

Mutations in SPOP E3 ligase gene are reportedly associated with genome-wide DNA hypermethylation in prostate cancer (PCa) although the underlying mechanisms remain elusive. Here, we demonstrate that SPOP binds and promotes polyubiquitination and degradation of histone methyltransferase and DNMT interactor GLP. SPOP mutation induces stabilization of GLP and its partner protein G9a and aberrant upregulation of global DNA hypermethylation in cultured PCa cells and primary PCa specimens. Genome-wide DNA methylome analysis shows that a subset of tumor suppressor genes (TSGs) including FOXO3, GATA5, and NDRG1, are hypermethylated and downregulated in SPOP-mutated PCa cells. DNA methylation inhibitor 5-azacytidine effectively reverses expression of the TSGs examined, inhibits SPOP-mutated PCa cell growth in vitro and in mice, and enhances docetaxel anti-cancer efficacy. Our findings reveal the GLP/G9a-DNMT module as a mediator of DNA hypermethylation in SPOP-mutated PCa. They suggest that SPOP mutation could be a biomarker for effective treatment of PCa with DNA methylation inhibitor alone or in combination with taxane chemotherapeutics.

FOXA1 overexpression suppresses interferon signaling and immune response in cancer.

Androgen receptor-positive prostate cancer (PCa) and estrogen receptor-positive luminal breast cancer (BCa) are generally less responsive to immunotherapy compared with certain tumor types such as melanoma. However, the underlying mechanisms are not fully elucidated. In this study, we found that FOXA1 overexpression inversely correlated with interferon (IFN) signature and antigen presentation gene expression in PCa and BCa patients. FOXA1 bound the STAT2 DNA-binding domain and suppressed STAT2 DNA-binding activity, IFN signaling gene expression, and cancer immune response independently of the transactivation activity of FOXA1 and its mutations detected in PCa and BCa. Increased FOXA1 expression promoted cancer immuno- and chemotherapy resistance in mice and PCa and BCa patients. These findings were also validated in bladder cancer expressing high levels of FOXA1. FOXA1 overexpression could be a prognostic factor to predict therapy resistance and a viable target to sensitize luminal PCa, BCa, and bladder cancer to immuno- and chemotherapy.

Targeting HER2 in patient-derived xenograft ovarian cancer models sensitizes tumors to chemotherapy.

Ovarian cancer is the most lethal gynecologic malignancy. About 75% of ovarian cancer patients relapse and/or develop chemo-resistant disease after initial response to standard-of-care treatment with platinum-based therapies. HER2 amplifications and overexpression in ovarian cancer are reported to vary, and responses to HER2 inhibitors have been poor. Next generation sequencing technologies in conjunction with testing using patient-derived xenografts (PDX) allow validation of personalized treatments. Using a whole-genome mate-pair next generation sequencing (MPseq) protocol, we identified several high grade serous ovarian cancers (HGS-OC) with DNA alterations in genes encoding members of the ERBB2 pathway. The efficiency of anti-HER2 therapy was tested in three different PDX lines with the identified alterations and high levels of HER2 protein expression. Treatment responses to pertuzumab or pertuzumab/trastuzumab were compared in each PDX line WITH standard carboplatin and paclitaxel combination treatment. In all three PDX models, HER2-targeted therapy resulted in significant inhibition of tumor growth compared with untreated controls. However, the responses in each case were inferior to those to chemotherapy, even for chemo-resistant lines. When chemotherapy and HER2-targeted therapy were administered together, a significant regression of tumor was observed after 6 weeks of treatment compared with chemotherapy alone. Post-treatment analysis of these tissues revealed that inhibition of the ERBB2 pathway occurred at the level of phosphorylation and expression of downstream targets. In conclusion, while targeting of presumably activated ERBB2 pathway alone in HGS-OC results in a modest treatment benefit, a combination therapy including both chemotherapy drugs and HER2 inhibitors provides a far better response. Further studies are needed to address development of recurrence and sensitivity of recurrent disease to HER2-targeted therapy.

LY2157299 Monohydrate, a TGF-ßR1 Inhibitor, Suppresses Tumor Growth and Ascites Development in Ovarian Cancer.

Transforming growth factor beta (TGF-ß) signaling has pleiotropic functions regulating cancer initiation, development, and metastasis, and also plays important roles in the interaction between stromal and cancer cells, making the pathway a potential therapeutic target. LY2157299 monohydrate (LY), an inhibitor of TGF-ß receptor I (TGFBRI), was examined for its ability to inhibit ovarian cancer (OC) growth both in high-grade serous ovarian cancer (HGSOC) cell lines and xenograft models. Immunohistochemistry, qRT-PCR, and Western blot were performed to study the effect of LY treatment on expression of cancer- and fibroblast-derived genes. Results showed that exposure to TGF-ß1 induced phosphorylation of SMAD2 and SMAD3 in all tested OC cell lines, but this induction was suppressed by pretreatment with LY. LY alone inhibited the proliferation, migration, and invasion of HGSOC cells in vitro. TGF-ß1-induced fibroblast activation was blocked by LY. LY also delayed tumor growth and suppressed ascites formation in vivo. In addition, independent of tumor inhibition, LY reduces ascites formation in vivo. Using OVCAR8 xenograft specimens we confirmed the inhibitory effect of LY on TGF-ß signaling and tumor stromal expression of collagen type XI chain 1 (COL11A1) and versican (VCAN). These observations suggest a role for anti-TGF-ß signaling-directed therapy in ovarian cancer.

Oncogenic pathways, molecularly targeted therapies, and highlighted clinical trials in non-small-cell lung cancer (NSCLC).

Non-small-cell lung cancer (NSCLC) has recently been associated with interesting molecular characteristics that have important implications in carcinogenesis and response to targeted therapies. The unsatisfactory treatment outcomes in advanced NSCLC with respect to long-term survival rates may be improved through a better understanding of the molecular etiology of this disease. For instance, several molecular alterations have been defined as "driver mutations," such as mutations in epidermal growth factor receptor (EGFR), Kirsten-rous avian sarcoma (KRAS), and a chromosome 2p inversion producing an EML4-ALK fusion gene (echinoderm microtubule-associated protein-like 4 fused with the anaplastic lymphoma kinase). Other key signaling pathways such as RAS/RAF/MEK, PI3K/AKT/mTOR (mammalian target of rapamycin), mesenchymal-epithelial transition (MET) kinase, LKB1, and insulin-like growth factor 1 (IGF-1) receptor (IGF-1R) have also been identified as novel targets for lung cancer treatment. In this review we focus on the molecular discoveries that have led to the clinical applications and trials of novel targeted agents, including the clinical trials that selectively studied patients who were predicted to achieve the greatest benefit based on the expression of correlative biomarkers.