Frequent Overexpression Research Articles

PKCiota promotes ovarian tumor progression through deregulation of cyclin E.

The high frequency of relapse of epithelial ovarian tumors treated with standard chemotherapy has highlighted the necessity to identify targeted therapies that can improve patient outcomes. The dynamic relationship between Cyclin E and PKCiota frequent overexpression in high-grade ovarian tumors poses a novel pathway for therapeutic investigation. We hypothesized that a PI3K dependent signaling pathway activating PKCiota perpetuates cyclin E deregulation during ovarian tumorigenesis. We observed a positive correlation between PKCiota and cyclin E in a panel of 19 ovarian cancer cell lines. Modulation of cyclin E had no effect on PKCiota knockdown/overexpression however PKCiota differentially regulated cyclin E expression. In the serous ovarian cancer cells (IGROV, OVCAR-3), shPKCiota decreased proliferation, caused a G1 arrest, and significantly prolonged overall survival in xenograft mouse models. In vitro shPKCiota decreased the ability of IGROV cells to grow under anchorage independent conditions and form aberrant acini, which was dependent upon Ad-cyclin E or Ad-LMW-E expression. RPPA analysis of PKCiota wild-type, catalytic active, dominant negative protein isoforms strengthened the association between phospho-PKCiota levels and PI3K pathway activation. Inhibitors of PI3K coordinately decreased phospho-PKCiota and Cyclin E protein levels. In conclusion, we have identified a PI3K/PKCiota/Cyclin E signaling pathway as a therapeutic target during ovarian tumorigenesis.

Abstract 2835: MDM2 antagonist-based therapeutic response is discriminated by a 4-gene signature in acute myeloid leukemia patients

Abstract The activity of p53, a key tumor suppressor is tightly controlled by MDM2-mediated ubiquination and degradation. Nutlins, a class of small-molecule MDM2 antagonists, have been characterized as drivers of p53 re-activation. Acute myeloid leukemia (AML) is uniquely sensitive to p53 re-activation as ∼90% of cases have wild-type TP53 and frequent MDM2 overexpression to overcome mechanisms of oncogene addiction. Personalized theranostic strategies may distinguish patients likely to clinically benefit from MDM2-antagonist therapy. Association between MDM2 antagonist (RG7112) growth inhibition (IC50s) in 287 human cancer cell lines (Cell Lines for Oncology/Chugai Accumulative Tumor Encyclopedia), and pretreatment RNAseq profiling established a classifier comprising MDM2, XPC, BBC3, and CDKN2A. This signature significantly associated with cell-line efficacy to MDM2 antagonist (odds ratio = 2.53; P<0.001) and discriminated MDM2 antagonist-sensitive (IC50 10 uM) better than MDM2 mRNA or TP53 mutation status alone (AUC = 0.92). Multivariate logistic regression indicated signature scores were significant (odds ratio = 1.84; P<0.001) when adjusted for TP53 mutation status. RG7112 treatment was assessed in a phase 1 dose escalation trial in relapsed/refractory AML patients (NO21279). Signature scores of AML patient blood specimens at baseline significantly associated with clinical response (PD<HI<MLFS<CR; Spearman correlation coefficient 0.58; P<0.001); and with pharmacodynamic biomarker response, defined as change in MDM2 mRNA expression in blood (Spearman correlation coefficient 0.41; P = 0.02). Patient response was discriminated by the signature with 100% sensitivity/71% specificity (Wilcoxon p = .0007, AUC = 0.72). Monitoring of signature with clinical response in a second AML Phase 1/1b clinical trial NP28679 with a next generation nutlin-class MDM2 Antagonist RG7388 validated this panel as significantly discriminating MDM2 antagonist therapeutic responders and non-responders in AML patients (Wilcoxon Rank Sum Test P = 0.008; AUC = .75). In summary, we demonstrate that a biological classifier discriminates response broadly to MDM2-antagonist therapy. The level of evidence attained by cell line efficacy modeling and response assessments in trial NO21279 (with MDM2 antagonist RG7112) and now in trial NP28679 (with MDM2 antagonist RG7388) adds substantial weight to the validity of this panel. Citation Format: Hua Zhong, Gong Chen, Lori Jukofsky, David Geho, Sung Won Han, Fabian Birzele, Sabine Bader, Lucia Himmelein, James Cai, Zayed Albertyn, Mark Rothe, Laurent Essioux, Helmut Burtscher, Steven A. Middleton, Lin-Chi Chen, Markus Dangl, William E. Pierceall, Gwen Nichols. MDM2 antagonist-based therapeutic response is discriminated by a 4-gene signature in acute myeloid leukemia patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2835. doi:10.1158/1538-7445.AM2015-2835

Sequencing of 279 cancer genes in ampullary carcinoma reveals trends relating to histologic subtypes and frequent amplification and overexpression of ERBB2 (HER2)

The biological relevance of histological subtyping of ampullary carcinoma into intestinal vs pancreaticobiliary types remains to be determined. In an effort to molecularly profile these subtypes of ampullary carcinomas, we conducted a two-phase study. In the discovery phase, we identified 18 pancreatobiliary-type ampullary carcinomas and 14 intestinal-type ampullary carcinomas using stringent pathologic criteria and performed next-generation sequencing targeting 279 cancer-associated genes on these tumors. Although the results showed overlapping of genomic alterations between the two subtypes, trends including more frequent KRAS alterations in pancreatobiliary-type ampullary carcinoma (61 vs 29%) and more frequent mutations in APC in intestinal-type ampullary carcinoma (43 vs 17%) were observed. Of the entire cohort of 32 tumors, the most frequently mutated gene was TP53 (n=17); the most frequently amplified gene was ERBB2 (n=5); and the most frequently deleted gene was CDKN2A (n=6). In the second phase of the study, we aimed at validating our observation on ERBB2 and assessed ERBB2 amplification and protein overexpression in a series of 100 ampullary carcinomas. We found that (1) gene amplification and immunohistochemical overexpression of ERBB2 occurred in 13% of all ampullary carcinomas, therefore providing a potential target for anti-HER2 therapy in these tumors; (2) amplification and immunohistochemical expression correlated in all cases, thus indicating that immunohistochemistry could be used to screen tumors; and (3) none of the 14 ERBB2-amplified tumors harbored any downstream driver mutations in KRAS/NRAS, whereas 56% of the cases negative for ERBB2 amplification did, an observation clinically pertinent as downstream mutations may cause primary resistance to inhibition of EGFR family members.

Abstract 2252: Overexpression of APOBEC3B enhances invasiveness of hepatocellular carcinoma

Abstract This study aims at revealing the roles of APOBEC3B (A3B) in human hepatocellular carcinoma (HCC). HCC is a leading cancer worldwide and specifically prevalent in Southeast Asia, due to prevalent hepatitis B virus (HBV) infection. Recent evidence has implicated A3B, a DNA deaminase, as a source of mutations in breast, cervical and bladder cancers. For example, A3B was found upregulated and active in the majority of breast cancer cell lines, and its upregulation in tumors correlated with increased C-to-T transition and overall base substitution mutations. A3B is one of seven APOBEC3 deaminases, which is responsible for providing innate immunity to a large number of DNA-based viruses. All these enzymes exhibit DNA deaminase activity. Transgenic expression of APOBEC1 and AID can induce tumor formation in mice which suggests links between mutagenesis, immunity and viral infection in cancer development. However, their roles in HCC remains largely undiscovered. We sequenced 16 pairs of HCC and corresponding non-tumorous livers using whole transcriptome sequencing (RNA-seq) and exome sequencing. We found that A3B expression was significantly overexpressed in HCC as compared to the corresponding non-tumorous liver for 13 of the 16 samples (81.3%) (p < 0.001). Moreover, the frequency of C-to-U and G-to-A mutations was associated with the metastasis status and significant association was detected at RNA level (p = 0.015) while a similar trend was also observed at the DNA level (p = 0.059 for C>T plus G>A events). To validate the expression in a larger cohort of human HCCs, we performed real-time quantitative PCR (qPCR) on 55 pairs of human HCCs. We consistently observed a frequent (70.9%) and significant overexpression (p<0.001) of A3B in HCCs. The result was also confirmed at the protein level by immunohistochemistry and western blotting. Clinical-pathological analysis revealed that A3B overexpression in HCCs was significantly associated with more aggressive tumor behavior including the presence of tumor microsatellite formation (p = 0.009), venous invasion (p = 0.021), direct invasion into the adjacent liver tissue (p = 0.033) and more advanced tumor stages (p = 0.017). In addition, overexpression of A3B in HCCs positively correlated with the presence of HBX truncation (P = 0.017). We also examined the A3B expression in a panel of HCC cell lines and found that the A3B mRNA levels were higher in the HCC cell lines with higher metastatic potential. In vitro cell migration and invasion assays also showed that the HCC cells which had higher expression levels of A3B had higher migratory and invasive abilities. In conclusion, we demonstrated that A3B was overexpressed in HCC and its overexpression was associated with more aggressive tumor behavior. A3B overexpression might enhance the metastatic potential of HCC cells. Citation Format: Wei Ma, Daniel Wai Hung Ho, Irene Oi Lin Ng. Overexpression of APOBEC3B enhances invasiveness of hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2252. doi:10.1158/1538-7445.AM2015-2252

Abstract 4324: Predictive biomarker signatures for IAP inhibitor CUDC-427

Abstract The Inhibitors of Apoptosis (IAP) are a family of functionally related proteins that serve as endogenous regulators of apoptosis. The frequent overexpression of IAP proteins allows cancer cells to evade apoptosis and develop drug resistance, making them attractive targets for cancer therapies. CUDC-427 is a potent small molecule IAP antagonist currently tested in a Phase 1 clinical trial for solid tumors and lymphomas. Although only 10% of the cancer cell lines are sensitive to single-agent CUDC-427 in vitro, significant anti-tumor activity has been observed in xenograft models. These observations highlight the importance of identifying patients with sensitive tumors to better target CUDC-427 for specific patient populations. Previously, we have reported TNF family ligand induction and decrease in XIAP levels as potential predictive biomarkers for response to CUDC-427. However, this prediction method requires the detection of biomarker levels in post-treatment samples, which may not always be feasible in clinical setting. Therefore, we sought to assess predictive genetic markers of response to CUDC-427 treatment for patient stratification. Using an in vitro cell viability assay, single-agent activity of CUDC-427 was assessed against a panel of 90 hematological and solid tumor cell lines from the Cancer Cell Line Encyclopedia (CCLE) collection. These results and genomic data available from the CCLE database including gene expression, DNA copy number and mutation status were used in the elastic net analysis to identify predictors associated with drug response. A set of gene signatures containing about 10 significant predictors identified by this approach was further validated and refined in an independent set of 61 CCLE cell lines. The clinical relevance of these gene signatures was validated by searching the cBioPortal Cancer Genomics database. The results indicate that these signatures frequently occur in several solid and hematologic cancers. To further validate this set of gene signatures, single-agent activity of CUDC-427 was evaluated in 30 patient-derived xenograft tumor models and 12 cell-line-derived xenograft models including breast and ovarian cancers as well as lymphomas. Daily treatment with CUDC-427 induced 60% or greater tumor growth inhibition in 20 of the 42 models tested, including 4 highly sensitive models that demonstrated tumor regression. Whole genome data including mutation status, DNA copy number and mRNA expression profiles of these xenograft tumors were assessed to provide independent in vivo validation and to further refine the gene signatures generated in vitro. In conclusion, a set of gene signatures identified through this work can potentially be used as biomarkers to predict in vivo activity of CUDC-427 across multiple tumor types. These results will provide a basis for the development of predictive assays to aid selection of patients whose tumors may be sensitive to CUDC-427 treatment. Citation Format: Kaiming Sun, Ze Tian, Qi Zhang, Maria Samson, Ruzanna Atoyan, Mylissa Borek, Steven Dellarocca, Brian Zifcak, Troy Patterson, Anna W. Ma, Guangxin Xu, Michael J. Wick, Richard Rickles, Jing Wang. Predictive biomarker signatures for IAP inhibitor CUDC-427. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4324. doi:10.1158/1538-7445.AM2015-4324

Abstract A89: Targeting the MYC activation and degradation pathway for the treatment of pancreatic cancer

Abstract Pancreatic cancer is a disease with a high rate of mortality, as it is generally diagnosed in the advanced stages when few effective treatments are available. Given the clinical aggressivity of this disease and lack of good treatment options, the development of new therapeutic agents is of the upmost importance. The c-MYC (MYC) oncoprotein is a critical transcription factor that regulates many diverse cellular functions by either activating or suppressing downstream target genes. High levels of MYC expression occur in a wide variety of human tumors, and animal models demonstrate MYC-induced tumorigenesis in many tissues. It has been shown that the MYC gene is frequently amplified in human pancreatic cancer and that MYC mRNA and/or protein are often overexpressed. However, what pathways contribute to this overexpression or whether MYC can be therapeutically targeted in pancreatic cancer is yet not known. Work in our laboratory has elucidated a complex signaling pathway that regulates MYC protein stability and transcriptional activity. RAS activation in early G1 leads to ERK-dependent phosphorylation of MYC at Serine62 (pS62-MYC), which stabilizes MYC. pS62-MYC is then recognized by the phosphorylation-directed Pin1 prolyl isomerase, which isomerizes Proline63 (P63) to cis, enhancing MYC’s recruitment to, and transactivation of, pro-growth target genes. Later in G1, when RAS activation decreases, GSK3β phosphorylates MYC at T58 (pT58-MYC). Following a second isomerization by Pin1, the trans-specific phosphatase PP2A-B56α removes the stabilizing S62 phosphate. pT58-MYC is then recognized by the E3 ubiquitin ligase SCFFbw7 and degraded by the proteasome. We have found that this pathway is frequently deregulated in human cancer leading to elevated pS62, decreased pT58, and increased c-Myc stability and activity. Here, we show that MYC is overexpressed and stabilized in pancreatic cancer cells. Additionally, we find aberrant MYC phosphorylation in primary human pancreatic cancer tissue, suggesting that the pathway that controls MYC phosphorylation is deregulated in human pancreatic cancer. Therefore, we hypothesized that the pathways regulating MYC phosphorylation and activation might represent new therapeutic targets. We are pursuing two different approaches to target MYC in pancreatic cancer: 1) inhibiting Pin1, the prolyl isomerase that co-activates pS62-MYC, and 2) activation of PP2A, the phosphatase that destabilizes MYC protein. We have observed decreased PP2A activity in pancreatic cancer cells, and have found that two endogenous inhibitors of PP2A, SET and CIP2A, are frequently overexpressed in pancreatic cancer cells and primary patient samples. This overexpression correlates with aberrant phosphorylation and stabilization of MYC. Furthermore, knockdown of SET or CIP2A, or inhibition of SET using a peptide mimetic (OP449), increases PP2A activity and reduces the tumorigenic potential of pancreatic cancer cells both in vitro and in vivo. In addition to increased SET and CIP2A expression in pancreatic cancer, we also observe frequent overexpression of Pin1 in human pancreatic cancer cell lines and primary patient tumor tissue and find that Pin1 knockdown or inhibition reduces the oncogenic potential of pancreatic cancer cells both in vitro and in vivo. Together, these findings suggest that MYC may play an important role in pancreatic cancer, and that targeting the pathway that regulates MYC activity and protein stability may be a viable therapeutic approach for human pancreatic cancer. Citation Format: Amy S. Farrell, Brittany Allen-Petersen, Colin J. Daniel, Xiaoyan Wang, Zhiping Wang, Dale J. Christensen, Brett Sheppard, Rosalie C. Sears. Targeting the MYC activation and degradation pathway for the treatment of pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A89.

A phase II study of alisertib (MLN8237) in recurrent or persistent uterine leiomyosarcoma: An NRG Oncology/Gynecologic Oncology Group Study (GOG-0231D).

e16512 Background: uLMS is an aggressive disease with limited therapeutic options. Genome wide transcriptional profiling of uterine leiomyosarcoma (uLMS) has identified frequent overexpression of g...

Photochemical activation of MH3-B1/rGel: a HER2-targeted treatment approach for ovarian cancer.

HER2-targeted therapy has been shown to have limited efficacy in ovarian cancer despite frequent overexpression of this receptor. Photochemical internalization (PCI) is a modality for cytosolic drug delivery, currently undergoing clinical evaluation. In the present project we studied the application of PCI in combination with the HER2-targeted recombinant fusion toxin, MH3-B1/rGel, for the treatment of ovarian cancer. The SKOV-3 cell line, resistant to trastuzumab- and MH3-B1/rGel- monotherapy, was shown to respond strongly to PCI of MH3-B1/rGel to a similar extent as observed for the treatment-sensitive SK-BR-3 breast cancer cells. Extensive hydrolytic degradation of MH3-B1/rGel in acidic endocytic vesicles was indicated as the mechanism of MH3-B1/rGel resistance in SKOV-3 cells. This was shown by the positive Pearson's correlation coefficient between Alexa488-labeled MH3-B1/rGel and Lysotracker in SKOV-3 cells in contrast to the negative Pearson's correlation coefficient in SK-BR-3 cells. The application of PCI to induce the release of MH3-B1/rGel was also demonstrated to be effective on SKOV-3 xenografts. Application of PCI with MH3-B1/rGel was further found highly effective in the HER2 expressing HOC-7 and NuTu-19 ovarian cancer cell lines. The presented results warrant future development of PCI in combination with MH3-B1/rGel as a novel therapeutic approach in preclinical models of ovarian cancer.

P35 Genomic profiling of intestinal-type sinonasal adenocarcinoma reveals a subgroup of patients with favourable clinical outcome

Intestinal-type sinonasal adenocarcinomas (ITAC) are rare tumors, related to occupational exposure to wood and leather dust. Patients with ITAC carry a poor prognosis and recurrent disease is the main cause of mortality. The purpose of this study was to analyse genome-wide copy number alterations (CNAs) in a large series of cases, aiming to identify genetic events involved in ITAC development and progression. DNA was isolated from 61 frozen ITAC tissue samples including all histological subtypes and analysed by high-resolution microarray CGH. Results were correlated to previously obtained genetic and immunohistochemical data and to clinico-pathological characteristics and follow-up data. All but three cases showed CNAs. Most frequent gains were found at chromosomal loci 5p, 7p, 8q, 12p and 20, whereas recurrent deletions were observed at 4q, 5q, 8p, 10q, 17p and 18q. High level amplifications included 7p12, 8q24, 11q13 and 19q11. Cluster analysis revealed a subgroup of cases characterized by carrying few CNAs (mean 8 versus 45). In addition, these cases showed absence of TP53 mutation and more frequent overexpression of COX2 and NFkB compared to the other cases. Overall survival was significantly better in this subgroup (p = 0.012). Genomic profiling revealed a subset of patients with ITAC with favourable clinical outcome, independent from established prognostic clinico-pathological parameters such as tumor stage and histological subtype. It may be speculated that this subset of tumors arises through a process of tumorigenesis that does not involved gross chromosomal instability as in the majority of epithelial tumors.

Retrospective review using targeted deep sequencing reveals mutational differences between gastroesophageal junction and gastric carcinomas.

BackgroundAdenocarcinomas of both the gastroesophageal junction and stomach are molecularly complex, but differ with respect to epidemiology, etiology and survival. There are few data directly comparing the frequencies of single nucleotide mutations in cancer-related genes between the two sites. Sequencing of targeted gene panels may be useful in uncovering multiple genomic aberrations using a single test.MethodsDNA from 92 gastroesophageal junction and 75 gastric adenocarcinoma resection specimens was extracted from formalin-fixed paraffin-embedded tissue. Targeted deep sequencing of 46 cancer-related genes was performed through emulsion PCR followed by semiconductor-based sequencing. Gastroesophageal junction and gastric carcinomas were contrasted with respect to mutational profiles, immunohistochemistry and in situ hybridization, as well as corresponding clinicopathologic data.ResultsGastroesophageal junction carcinomas were associated with younger age, more frequent intestinal-type histology, more frequent p53 overexpression, and worse disease-free survival on multivariable analysis. Among all cases, 145 mutations were detected in 31 genes. TP53 mutations were the most common abnormality detected, and were more common in gastroesophageal junction carcinomas (42% vs. 27%, p = 0.036). Mutations in the Wnt pathway components APC and CTNNB1 were more common among gastric carcinomas (16% vs. 3%, p = 0.006), and gastric carcinomas were more likely to have ≥3 driver mutations detected (11% vs. 2%, p = 0.044). Twenty percent of cases had potentially actionable mutations identified. R132H and R132C missense mutations in the IDH1 gene were observed, and are the first reported mutations of their kind in gastric carcinoma.ConclusionsPanel sequencing of routine pathology material can yield mutational information on several driver genes, including some for which targeted therapies are available. Differing rates of mutations and clinicopathologic differences support a distinction between adenocarcinomas that arise in the gastroesophageal junction and those that arise in the stomach proper.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1021-7) contains supplementary material, which is available to authorized users.

Selective inhibition of EZH2 and EZH1 enzymatic activity by a small molecule suppresses MLL-rearranged leukemia

AbstractEnhancer of zeste homolog 2 (EZH2) and related EZH1 control gene expression and promote tumorigenesis via methylating histone H3 at lysine 27 (H3K27). These methyltransferases are ideal therapeutic targets due to their frequent hyperactive mutations and overexpression found in cancer, including hematopoietic malignancies. Here, we characterized a set of small molecules that allow pharmacologic manipulation of EZH2 and EZH1, which include UNC1999, a selective inhibitor of both enzymes, and UNC2400, an inactive analog compound useful for assessment of off-target effect. UNC1999 suppresses global H3K27 trimethylation/dimethylation (H3K27me3/2) and inhibits growth of mixed lineage leukemia (MLL)–rearranged leukemia cells. UNC1999-induced transcriptome alterations overlap those following knockdown of embryonic ectoderm development, a common cofactor of EZH2 and EZH1, demonstrating UNC1999's on-target inhibition. Mechanistically, UNC1999 preferentially affects distal regulatory elements such as enhancers, leading to derepression of polycomb targets including Cdkn2a. Gene derepression correlates with a decrease in H3K27me3 and concurrent gain in H3K27 acetylation. UNC2400 does not induce such effects. Oral administration of UNC1999 prolongs survival of a well-defined murine leukemia model bearing MLL-AF9. Collectively, our study provides the detailed profiling for a set of chemicals to manipulate EZH2 and EZH1 and establishes specific enzymatic inhibition of polycomb repressive complex 2 (PRC2)–EZH2 and PRC2-EZH1 by small-molecule compounds as a novel therapeutics for MLL-rearranged leukemia.

HOTAIR enhanced aggressive biological behaviors and induced radio-resistance via inhibiting p21 in cervical cancer

We previously reported the frequent overexpression of HOX Antisense Intergenic RNA (HOTAIR) in human cervical cancer, which was significantly correlated with tumor progression and poor prognosis. In the present study, we investigated the detailed biological functions of HOTAIR in cervical cancer. In vitro, upregulation of HOTAIR inhibited apoptosis and promoted cellular proliferation, cell cycle progression, migration, and invasion; on the contrast, downregulation of HOTAIR induced more apoptosis, suppressed cellular proliferation, cell cycle, migration, and invasion. Moreover, a high level of HOTAIR was notably associated with radio-resistance and downregulation of p21 in the primary cultured cervical cancer cells. Further, we demonstrated that elevated HOTAIR could induce radio-resistance via inhibiting p21 in HeLa cells, while knockdown of HOTAIR upregulated p21 and consequentially increased the radio-sensitivity of C33A cells. Consistently, stable knockdown of HOTAIR significantly suppressed tumor growth and sensitized cervical cancer to radiotherapy in vivo. In conclusion, HOTAIR served as an onco-lncRNA in cervical cancer which could enhance various aggressive biological behaviors. Moreover, we proved that HOTAIR execute its functions mainly through inhibiting the p21 expression. These results proposed that targeting HOTAIR might be a potent therapeutic strategy in cervical cancer, especially for those patients who accepted radiotherapy.

FRα : une cible pour la thérapie photodynamique prophylactique des métastases péritonéales ovariennes ?

Partly due to delays in its diagnosis, ovarian cancer's prognosis remains dire after primary therapy. Treatment consists in complete cytoreductive surgery and platinum-based chemotherapy. Recurrence rates are disappointingly high, as 60 % of women with advanced epithelial ovarian cancer considered in remission will develop recurrent disease within five years. Special attention to undetected peritoneal metastasis and residual tumorous cells during surgery is necessary as they are the main predictors of recurrences. Targeted therapies aim to bring chemotherapy, radiotherapy and selective tumor photosensitizer (PS) agents to the targeted cell and its tumoral microenvironment. Folate receptor α (FRα) shows promising prospects in targeting ovarian cancerous cells. Indeed, with good specificity and frequent overexpression in ovarian cancer, FRα is a recurrent topic in recent publications. The aim of this review is to present FRα and the reasons that make it an ideal targeting ligand for ovarian carcinoma therapy. Prophylactic photodynamic therapy (PPDT) using new generation FRα-coupled agents combined with complete cytoreductive surgery could allow for a significant decrease in recurrence rates. Preclinical trials are being run in order to allow for human clinical applications.

Traitements systémiques des cancers du sein inflammatoires : un état des lieux

The poor prognosis of inflammatory breast cancer (IBC) is due to its strong metastatic potential. During the last three decades, the introduction of neoadjuvant chemotherapy (CT), and its improvement with successive additions of anthracyclines and then taxanes, allowed to double the survival. However, the 5-year survival still remains lower than 50%, with the pathological complete response (pCR) to neoadjuvant CT being a major prognostic factor. Since 1995, several innovative approaches have been evaluated. Initially, the trials of high-dose CT with hematopoietic stem cell transplantation have generated promising results, but ultimately failed to change standards of treatment, in particular because of its toxicity. More recently, a few targeted therapies, combined to conventional CT, have been assessed, due to the frequent overexpression of HER2 and EGFR and the important vascularization of IBC. Trastuzumab, a monoclonal antibody targeting HER2, has shown a clear advantage in terms of pCR and survival in studies dedicated to, HER2-positive locally advanced breast cancers, including IBC. Lapatinib, a dual tyrosine kinase inhibitor anti-HER2 and EGFR, has shown significant activity in two phase II studies dedicated to HER2-positive IBC. The interest of HER2-double blockade by the combination of trastuzumab-pertuzumab combined to docetaxel has been demonstrated in term of pCR in the NEOSPHERE study which also included HER2-positive IBC. Among the anti-angiogenic drugs tested in studies dedicated to IBC, bevacizumab has given the most interesting results in term of efficacy/toxicity ratio. In the Beverly 2 study HER2-positive IBC patients were treated by the combination chemotherapy, trastuzumab and bevacizumab: the rate of pCR was 64%, and the 3-year disease-free and overall survivals were 68% and 90%, respectively; the increase of endothelial cells circulating was inversely correlated to the probability of pCR. All those treatments have been extrapolated from standard breast cancers. Thus, a deep molecular knowledge of IBC appears to be critical in order to develop specific treatments effectively targeting its particular aggressiveness.

WWP2 is overexpressed in human oral cancer, determining tumor size and poor prognosis in patients: downregulation of WWP2 inhibits the AKT signaling and tumor growth in mice.

The WW domain containing E3 ubiquitin protein ligase 2 (WWP2) encodes a member of the Nedd4 family of E3 ligases, which catalyzes the final step of the ubiquitination cascade. WWP2 is involved in tumoral growth with degradation of the tumor suppressor phosphatase and tensin homologue deleted on chromosome TEN (PTEN). However, little is known about the mechanisms and roles of WWP2 in human malignancies including oral squamous cell carcinomas (OSCCs). We found frequent WWP2 overexpression in all OSCC-derived cell lines examined that was associated with cellular growth by accelerating the cell cycle in the G1 phase via degradation of PTEN and activation of the PI3K/AKT signaling pathway. Our in vivo data of WWP2 silencing showed dramatic inhibition of tumoral growth with increased expression of PTEN. Our 104 primary OSCCs had significantly higher expression of WWP2 than their normal counterparts. Moreover, among the clinical variables analyzed, enhanced WWP2 expression was correlated with primary tumoral size and poor prognosis. These data suggested that WWP2 overexpression contributes to neoplastic promotion via the PTEN/PI3K/AKT pathway in OSCCs. WWP2 is likely to be a biomarker of tumoral progression and prognosis and a potential therapeutic target for development of anticancer drugs in OSCCs.

Model Assembly for Estimating Cell Surviving Fraction for Both Targeted and Nontargeted Effects Based on Microdosimetric Probability Densities

We here propose a new model assembly for estimating the surviving fraction of cells irradiated with various types of ionizing radiation, considering both targeted and nontargeted effects in the same framework. The probability densities of specific energies in two scales, which are the cell nucleus and its substructure called a domain, were employed as the physical index for characterizing the radiation fields. In the model assembly, our previously established double stochastic microdosimetric kinetic (DSMK) model was used to express the targeted effect, whereas a newly developed model was used to express the nontargeted effect. The radioresistance caused by overexpression of anti-apoptotic protein Bcl-2 known to frequently occur in human cancer was also considered by introducing the concept of the adaptive response in the DSMK model. The accuracy of the model assembly was examined by comparing the computationally and experimentally determined surviving fraction of Bcl-2 cells (Bcl-2 overexpressing HeLa cells) and Neo cells (neomycin resistant gene-expressing HeLa cells) irradiated with microbeam or broadbeam of energetic heavy ions, as well as the WI-38 normal human fibroblasts irradiated with X-ray microbeam. The model assembly reproduced very well the experimentally determined surviving fraction over a wide range of dose and linear energy transfer (LET) values. Our newly established model assembly will be worth being incorporated into treatment planning systems for heavy-ion therapy, brachytherapy, and boron neutron capture therapy, given critical roles of the frequent Bcl-2 overexpression and the nontargeted effect in estimating therapeutic outcomes and harmful effects of such advanced therapeutic modalities.

Stathmin mediates hepatocyte resistance to death from oxidative stress by down regulating JNK.

Stathmin 1 performs a critical function in cell proliferation by regulating microtubule polymerization. This proliferative function is thought to explain the frequent overexpression of stathmin in human cancer and its correlation with a bad prognosis. Whether stathmin also functions in cell death pathways is unclear. Stathmin regulates microtubules in part by binding free tubulin, a process inhibited by stathmin phosphorylation from kinases including c-Jun N-terminal kinase (JNK). The involvement of JNK activation both in stathmin phosphorylation, and in hepatocellular resistance to oxidative stress, led to an examination of the role of stathmin/JNK crosstalk in oxidant-induced hepatocyte death. Oxidative stress from menadione-generated superoxide induced JNK-dependent stathmin phosphorylation at Ser-16, Ser-25 and Ser-38 in hepatocytes. A stathmin knockdown sensitized hepatocytes to both apoptotic and necrotic cell death from menadione without altering levels of oxidant generation. The absence of stathmin during oxidative stress led to JNK overactivation that was the mechanism of cell death as a concomitant knockdown of JNK1 or JNK2 blocked death. Hepatocyte death from JNK overactivation was mediated by the effects of JNK on mitochondria. Mitochondrial outer membrane permeabilization occurred in stathmin knockdown cells at low concentrations of menadione that triggered apoptosis, whereas mitochondrial β-oxidation and ATP homeostasis were compromised at higher, necrotic menadione concentrations. Stathmin therefore mediates hepatocyte resistance to death from oxidative stress by down regulating JNK and maintaining mitochondrial integrity. These findings demonstrate a new mechanism by which stathmin promotes cell survival and potentially tumor growth.

A fusogenic dengue virus-derived peptide enhances antitumor efficacy of an antibody-ribonuclease fusion protein targeting the EGF receptor.

Due to its frequent overexpression in a variety of solid tumors the epidermal growth factor receptor (EGFR) is a well-established target for therapeutic interventions in epithelial cancers. In order to target EGFR in head and neck cancer, we have generated a ribonuclease (RNase) fusion protein comprising a humanized anti-EGFR antibody single-chain Fv fragment (scFv) and Ranpirnase, an RNase from Rana pipiens. Fusion of Ranpirnase to the N-terminus of the scFv via a flexible glycine-serine linker (G4S)3 resulted in very poor cytotoxicity of the fusion protein. As endosomal accumulation and lysosomal degradation have been reported to diminish the antitumor efficacy of ribonuclease or toxin-based immunoagents, we explored a fusion peptide from dengue virus that has been reported to be involved in the endosomal escape of the virus. This peptide was introduced as a linker between Ranpirnase and the scFv moiety. The modified immunoRNase exhibited exceptionally high cytotoxicity toward EGFR-expressing head and neck cell lines without affecting specificity. These results indicate that endosomal entrapment needs to be considered for Ranpirnase-based immunoagents and might be overcome by the use of tailored transduction domains from viral proteins.

Abstract 1689: Synergistic effect of JQ1 and rapamycin for treatment of human osteosarcoma

Abstract Bromodomain and extra terminal domain (BET) proteins are important epigenetic regulators facillitating the transcription of genes in chromatin areas linked to acetylated histones. JQ1, a BET protein inhibitor, has antiproliferative activity againts many hematological and solid cancers, mainly through inhibition of c-myc and upregulation of p21. In this research, we investigated the use of JQ1 for human osteosarcoma (OS) treatment, due to the frequent copy number gain and overexpression of c-myc in OS cells. JQ1 significantly inhibited the proliferation and survival of seven OS cells (U2OS, G292, MG-63, HT-161, MNNG/HOS, SAOS-2, SJSA), at a relatively higher dose than other cancers (median IC50 = 7.35 μM). JQ1 induced G1 cell cycle arrest and premature senescence of OS cells, but produced little apoptosis. Interestingly, c-myc protein levels in JQ1-treated cells remained unchanged, whereas the upregulation of p21 protein was still observable, as noted by Western blots. Although effective in vitro, JQ1 failed to reduce the size of the MNNG/HOS xenografts in immunocompromised mice in vivo. To overcome the resistance of OS cells to JQ1 treatment, we tested JQ1 in combination with rapamycin. Rapamycin inhibits the assembly of mTOR complexes which is one of the important growth signaling pathways in many cancers including OS. JQ1 and rapamycin synergistically inhibited the growth and survival of OS cells in vitro. The drug combination nearly abrogated expression of c-myc protein, enhanced levels of p21, and induced apoptosis in OS cells in vitro. After 24 days of treatment in vivo, JQ1 (50mg/kg body weight) or rapamycin (1.5 mg/kg body weight) alone showed little effect on the size of human OS xenografts in nude mice. However, combination of both drugs significantly inhibited tumor growth by 85% and 73% (p<0.05 for both) compared to either JQ1 or rapamycin alone, respectively. In conclusion, JQ1 inhibited proliferation and survival of OS cells in vitro but failed to reduce growth of OS xenografts in immunodeficient mice. When combined with rapamycin, JQ1 synergistically inhibited proliferation of OS cells both in vitro and in vivo. Citation Format: Dhong Hyun Tony Lee, Jun Qi, James Bradner, Jonathan Said, Ngan Doan, Charles Forscher, H Phillip Koeffler. Synergistic effect of JQ1 and rapamycin for treatment of human osteosarcoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1689. doi:10.1158/1538-7445.AM2014-1689

TRIB1 supports prostate tumorigenesis and tumor-propagating cell survival by regulation of endoplasmic reticulum chaperone expression.

Endocrine therapy is the standard treatment for advanced prostate cancer; however, relapse occurs in most patients with few treatment options available after recurrence. To overcome this therapeutic hurdle, the identification of new molecular targets is a critical issue. The capability to proliferate in three-dimensional (3D) conditions is a characteristic property of cancer cells. Therefore, factors that regulate 3D growth are considered rational targets for cancer therapy. Here, we applied a functional genomic approach to the 3D spheroid cell culture model and identified TRIB1, a member of the Trib family of serine/threonine kinase-like proteins, as an essential factor for prostate cancer cell growth and survival. RNAi-mediated silencing of TRIB1 suppressed prostate cancer cell growth selectively under the 3D conditions. This effect was rescued by ectopic expression of an RNAi-resistant TRIB1 exogene. Gene signature-based analysis revealed that TRIB1 was related to endoplasmic reticulum (ER) pathways in prostate cancer and was required for expression of the ER chaperone GRP78, which is critical for prostate tumorigenesis. Of note, GRP78 was expressed preferentially in a subpopulation of prostate cancer cells that possess tumor-propagating potential, and these tumor-propagating cells were highly sensitive to TRIB1 and GRP78 depletion. In a xenograft model of human prostate cancer, TRIB1 depletion strongly inhibited tumor formation. Supporting these observations, we documented frequent overexpression of TRIB1 in clinical specimens of prostate cancer. Overall, our results indicated that the TRIB1-ER chaperone axis drives prostate tumorigenesis and the survival of the tumor-propagating cells.