Safety and Efficacy of CT041 in Patients With Refractory Metastatic Pancreatic Cancer: A Pooled Analysis of Two Early-Phase Trials

PURPOSE

CT041 is a chimeric antigen receptor (CAR)-modified T-cell therapy that specifically targets claudin18.2 in solid tumors. Here, we report the pooled analysis results of two exploratory clinical trials to evaluate CT041 in patients with previously treated pancreatic cancer (PC).

PATIENTS AND METHODS

These two multicenter, open-label phase I/Ib trials (CT041-CG4006, CT041-ST-01) have a similar target population and evaluation schedule. The primary objective was to assess the safety and tolerability of CT041, whereas secondary objectives included efficacy, pharmacokinetics, and immunogenicity.

RESULTS

The combined cohort comprised 24 patients with advanced PC. Among them, five patients (20.8%) had previously received one line of therapy, whereas 19 (79.2%) received ≥2 lines of therapy. The most common treatment-emergent adverse events of grade 3 or more were preconditioning-related hematologic toxicities. Cytokine release syndrome (CRS) and GI disorders were most reported grade 1 or 2 adverse events. The overall response rate and disease control rate were 16.7% and 70.8%. The median progression-free survival (mPFS) after infusion was 3.3 months (95% CI, 1.8 to 6.2), and the median overall survival (mOS) was 10.0 months (95% CI, 5.5 to 17.6). The median duration of response (mDoR)was 9.5 months (95% CI, 2.6 to Not reached), with a DoR rate at 12 months of 50% (95% CI, 5.8 to 84.5). The mPFS (6.0 v 1.0 months, P < .001) and mOS (17.6 v 4.0 months, P < .001) were prolonged in patients achieving partial response/stable disease than the progressive disease group. CA19-9 levels had reduced by at least 30% in 17 (70.8%) patients.

CONCLUSION

In patients with metastatic PC after progression on previous therapy, CT041 demonstrated a tolerable safety profile and encouraging anticancer efficacy signals. Response benefit observed here needs to be ascertained in the future.

First-in-human phase 1/2 study of autologous T cells engineered using the Sleeping Beauty System transposon/transposase to express T-cell receptors (TCRs) reactive against cancer-specific mutations in patients with advanced solid tumors

TPS2679

Background: In 2022 approximately 1.7 million Americans will die from solid cancers. Recently there have been significant advances in the genetic engineering of T lymphocytes to recognize neoantigens on tumors in vivo, resulting in remarkable cases of tumor regression and remission. Cancer cells frequently harbor KRAS, TP53, and EGFR somatic hotspot mutations that can be processed and presented by tumor HLA as neoantigens to T cells through their T-cell receptor (TCR). These neoantigens are not present in the normal tissues; thus, they are attractive targets for adoptive T cell therapy. Given the number and complexity of different neoantigen/HLA combinations on solid tumors, a TCR library approach is warranted. Therefore, we have developed a library of TCR-T cell therapies including those targeting shared KRAS, TP53 and EGFR mutations. Methods: Patients for whom a TCR matching the subject’s somatic mutation(s) and HLA type is available in our TCR library, and have progressive or recurrent disease following standard therapy are eligible for enrollment on this protocol. Patients with the following tumor types will be enrolled: ovarian, endometrial, colorectal, pancreatic, cholangiocarcinoma, and non-small cell lung cancer. This first-in-human study includes Screening, Pre-Treatment, Treatment and Follow-up Periods. During the Pre-Treatment Period, subjects will undergo apheresis for PBMCs isolation. The PBMCs will be transposed using the Sleeping Beauty system to express the subject’s mutation specific TCR. Bridging therapy after apheresis is allowed once the apheresis product has been accepted. During the Treatment Period, patients will undergo lymphodepletion with cyclophosphamide and fludarabine. After which, the TCR-T cell drug product will be administered to the subject by infusion at the assigned dose level. The starting dose level of Arm A (monotherapy) will be DL1 (5 x10 9 TCR+ Cells) administered on Day 0. Dose escalation will continue utilizing the accelerated BOIN design (planned escalation dose levels: 5 x10 9, 4 x10 10 and 1 x10 11 TCR+ Cells). In Arm B, if initiated by protocol, subjects will also receive aldesleukin (interleukin-2) infusion starting on Day 0 (within 24 hours of TCR-T cell product infusion) at 720K IU/kg, every eight hours for up to 4 days. The Follow-up Period will begin after the subject completes their Day 28 visit. Clinical and radiologic response will be assessed at 6 and 12 weeks after TCR-T cell drug product infusion and every 12 weeks thereafter until up to 2 years or study discontinuation (e.g., disease progression, initiation of new anti-cancer therapy, consent withdrawn), whichever occurs first. All subjects will continue to be followed in the Long-Term Follow-up Protocol for up to 15 years post-TCR-T cell drug product infusion. Clinical trial information: NCT05194735.

226 Neoantigen-specific TCR-T cells targeting shared hotspot mutations for adoptive cell therapy in common epithelial cancers

Background

EGFR, KRAS and TP53 have frequent somatic hotspot mutations giving rise to biologically relevant amino acid substitutions in EGFR, KRAS and p53 proteins, respectively, that can be processed and presented on the cell surface by human leukocyte antigen (HLA) molecules as neoantigens to T cells through their T-cell receptor (TCR). These mutations are critical for the cancer cell and are absent in normal tissue; thus, these shared neoantigens are attractive and likely safe targets. Given the complexity of different neoantigen/HLA combinations needed to effectively target a large patient population, a TCR library approach is warranted and can be used ”off-the-shelf” for any patient with matching somatic hotspot mutation and HLA restriction. Sleeping Beauty transposition is the most advanced non-viral gene transfer technology for TCR-T cells and is appealing for TCR libraries given its low cost, speed, and flexibility.

Methods

In this study, Sleeping Beauty transposons were constructed with TCRs targeting EGFR, KRAS and p53 neoantigens restricted by either or both HLA Class-I and HLA Class-II molecules. Donor T cells from peripheral blood were co-electroporated with TCR transposon and Sleeping Beauty transposase and grown in vitro to clinical scale quantities (>109 TCR-T cells) with high expression (>60%) of the introduced neoantigen-specific TCRs.

Results

The specificity of TCRs to neoantigens was confirmed in TCR-T cell co-cultures with antigen-presenting cells pulsed with peptides, which demonstrated interferon-γ secretion and/or up-regulation of 41BB on the TCR-T cell surface in response to the neoantigen with high avidity (<1 ng/mL for some TCRs) and negligible recognition of wild type peptides. Furthermore, TCR-T cells lysed tumor cells with endogenous expression of the somatic mutation and HLA restriction element but did not recognize tumor cells lacking either somatic mutation or HLA restriction element, indicating that the targeted neoantigens are normally displayed on the tumor cell at sufficient levels for elimination by TCR-T cells. Ziopharm has a cleared corporate-sponsored IND for a Phase 1/2 clinical trial, being conducted in collaboration with MD Anderson Cancer Center, in which patients with matching somatic hotspot mutation and HLA restriction will be identified, genes encoding suitable neoantigen-specific TCR will be inserted into their autologous T cells from peripheral blood by Sleeping Beauty transposition, and TCR-T cells will be adoptively transferred for the treatment of bile duct, colon, lung, pancreas and gynecological cancers.

Conclusions

Ziopharm’s library TCR-T cell program has the potential to result in safe, durable, objective clinical regressions of cancer at a commercial scale.

An Antibody-Drug Conjugate Targeting MUC1-Associated Carbohydrate CA6 Shows Promising Antitumor Activities

Glycosylation is a complex multienzyme-related process that is frequently deregulated in cancer. Aberrant glycosylation can lead to the generation of novel tumor surface-specific glycotopes that can be targeted by antibodies. Murine DS6 mAb (muDS6) was generated from serous ovary adenocarcinoma immunization. It recognizes CA6, a Mucin-1 (MUC1)-associated sialoglycotope that is highly detected in breast, ovarian, lung, and bladder carcinomas. SAR566658 antibody-drug conjugate (ADC) is a humanized DS6 (huDS6) antibody conjugated through a cleavable linker to the cytotoxic maytansinoid derivative drug, DM4. SAR566658 binds to tumor cells with subnanomolar affinity, allowing good ADC internalization and intracellular delivery of DM4, resulting in tumor cell death (IC₅₀ from 1 to 7.3 nmol/L). SAR566658 showed in vivo antitumor efficacy against CA6-positive human pancreas, cervix, bladder, and ovary tumor xenografts and against three breast patient-derived xenografts. Tumor regression was observed in all tumor models with minimal effective dose correlating with CA6 expression. SAR566658 displayed better efficacy than standard-of-care nontargeted tubulin binders. These data support the development of SAR566658 in patients with CA6-expressing tumors.

Tumor mutation burden: from comprehensive mutational screening to the clinic

The recent advent of immunomodulatory therapies into the clinic has demanded the identification of innovative predictive biomarkers to identify patients most likely to respond to immunotherapy and support the design of tailored clinical trials. Current molecular testing for selection of patients with gastrointestinal or pulmonary carcinomas relies on the prevalence of PD-L1 expression in tumor as well as immune cells by immunohistochemistry and/or on the evaluation of the microsatellite status. Tumor Mutational Burden (TMB) has emerged as a promising novel biomarker in this setting to further aid in patient selection. This has been facilitated by the increasing implementation of molecular pathology laboratories with comprehensive next generation sequencing (NGS) technologies. However, the significant overall costs and expertise required for the interpretation of NGS data has limited TMB evaluation in routine diagnostics, so far. This review focuses on the current use of TMB analysis in the clinical setting in the context of immune checkpoint inhibitor therapies.

Abstract 235: Preclinical activity of an antibody drug conjugate targeting tumor specificmuc1 structural peptide-glycotope

SAR566658 antibody drug conjugate (ADC) is a humanized DS6 (huDS6) antibody conjugated through a cleavable linker to the cytotoxic maytansinoid derivative DM4 that has been evaluated in the clinical setting. The purpose of our work was; 1) characterize the epitope targeted by anti DS6 on mucin1, 2) determine the prevalence of antigen expression in a patient population and 3) further explore preclinical activities of the ADC. Murine DS6 monoclonal antibody (muDS6) was generated from serous ovary adenocarcinoma immunization of immunocompetent mice. It specifically recognizes a MUC-1 tandem repeat domain in the context of cancer associated glycosylation. CA6-positive MUC-1 carries mucin-type O-linked glycans with α2,3-sialylated and β1,4-galactosylated termini, and antibody binding was abrogated by treating MUC-1 with specific glycosidases that remove either one of these glycan structures. However, the antibody did not bind to synthetic glycans modeled according to the major O-glycans of MUC-1. Our characterization of the peptide-glycotope leads us to conclude that tumor associated glycosylation is essential for the formation of the epitope on the peptide sequence of the MUC-1 tandem repeat domain. CA6 expression was evaluated by immunohistochemistry in paraffin embedded tumor tissue samples: 35.2% of breast cancer patients, 70,1% of ovarian cancer patients and 58,5% of bladder cancer patients have at least 30% of CA6 positive cells with an intensity of 2+/3+ in a multinational population-based study. In pre-clinical in vivo models, SAR566658 induced anti-tumor activity against CA6 positive tumor models of human pancreas, cervix and bladder cancer as well as and 3 Breast Patient-Derived Xenografts (PDX). Efficacy was correlated with MUC1-CA6 expression levels. In 3 additional models, SAR566658 showed anti-tumor activity that was more potent when compared to 3 conventional tubulin cytotoxic agents, docetaxel, vinorelbine and vinblastine.

Citation Format: Marc Trombe, Anne Caron, Alexia Tellier, Chantal Carrez, Stephane Guérif, Severine Clavier, Nathalie Karst, Juhani Saarinen, Tero Satomaa, Virve Pitkänen, Olli Aitio, Annamari Heiskanen, Matteo Fassan, Jan Pinkas, Raffaele Baffa, Veronique Blanc, Celine Nicolazzi. Preclinical activity of an antibody drug conjugate targeting tumor specificmuc1 structural peptide-glycotope [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 235.

First-in-human, phase I study of PF-06647263, an anti-EFNA4 calicheamicin antibody-drug conjugate, in patients with advanced solid tumors

PF-06647263, a novel antibody-drug conjugate consisting of an anti-EFNA4 antibody linked to a calicheamicin payload, has shown potent antitumor activity in human xenograft tumor models, including triple-negative breast cancer (TNBC). In the dose-escalation part 1 of this multicenter, open-label, phase I study (NCT02078752), successive cohorts of patients (n, 48) with advanced solid tumors and no available standard therapy received PF-06647263 every 3 weeks (Q3W) or every week (QW), following a modified toxicity probability interval (mTPI) method (initial dosing: 0.015 mg/kg Q3W). Primary objective in part 1 was to estimate the maximum tolerated dose (MTD) and select the recommended phase 2 dose (RP2D). In part 2 (dose-expansion cohort), 12 patients with pretreated, metastatic TNBC received PF-06647263 at the RP2D to further evaluate tumor response and overall safety. PF-06647263 QW administration (n, 23) was better tolerated than the Q3W regimen (n, 25) with only 1 DLT reported (thrombocytopenia). The most common AEs with the QW regimen (fatigue, nausea, vomiting, mucosal inflammation, thrombocytopenia, and diarrhea) were mostly mild to moderate in severity. The MTD was not estimated. PF-06647263 exposures increased in a dose-related manner across the doses evaluated. The RP2D was determined to be 0.015 mg/kg QW. Six (10%) patients achieved a confirmed partial response and 22 (36.7%) patients had stable disease. No correlations were observed between tumor responses and EFNA4 expression levels. Study findings showed manageable safety and favorable PK for PF-06647263 administered QW at the RP2D, with preliminary evidence of limited antitumor activity in patients with TNBC and ovarian cancer.

A phase I study of PF-06647263, a novel EFNA4-ADC, in patients with metastatic triple negative breast cancer

2511

Background: PF-06647263 is an anti-Ephrin-A4 (EFNA4) antibody drug conjugate (ADC) composed of a humanized mAb, a hydrazone cleavable linker, and calicheamicin, a potent DNA damaging agent. Higher levels of EFNA4 expression have been shown in tumor versus normal tissue, including in two thirds of triple negative breast cancers (TNBC). In vivo preclinical studies demonstrate PF-06647263 induced tumor regression in TNBC models. Methods: In Part 1 of a dose escalation, cohorts of 2-12 patient (pts) with solid tumors that were unselected for EFNA4 expression received escalating doses of PF-06647263 once every 3 weeks (Q3W, Cohort A) or weekly (QW, Cohort B). Escalations were based on mTPI design. An expansion cohort enrolled TNBC patients (n=12) unselected for EFNA4 expression. Efficacy, safety, EFNA4 RNA expression, pharmacokinetic (PK) and anti-drug antibody development were assessed. Results: Part 1 (dose escalation):A total of 48 pts (25 in A and 23 in B) wereenrolled. The most common treatment related adverse events (AE) were fatigue (65%), and nausea (60%), thrombocytopenia (40%), and decreased appetite (38%). DLTs were observed in 6 and 2 pts in the Q3W and QW regimens, respectively. One confirmed VOD and one suspected VOD were observed in two patients in the Q3W schedule. The maximum tolerated dose (and RP2D) was determined to be 0.015 mg/kg QW. Confirmed partial responses (PR) were observed in 5 pts (3 Ovarian Ca and 2 TNBC). Part 2 (TNBC dose expansion at RP2D)data are available on 10 of 12 pts treated (2 ongoing). The most common adverse events (AE) were nausea (40%), asthenia (30%), vomiting (30%) and mucosal inflammation (30%). No objective RECIST response was observed; there was no dependency with duration of treatment relative to EFNA4 expression. Conclusions: In Part 1 of this study, PF-06647263 was generally well-tolerated in the QW schedule and some anti-tumor activity was observed in heavily pretreated pts with EFNA4 unselected advanced malignancies. However, in the expansion cohort (Part 2) at RP2D in TNBC no objective responses were observed regardless of EFNA4 expression. Final safety, efficacy, expression and PK data will be reported at the meeting. Clinical trial information: NCT02078752.

Anti-miR-21 Suppresses Hepatocellular Carcinoma Growth via Broad Transcriptional Network Deregulation

Hepatocellular carcinoma (HCC) remains a significant clinical challenge with few therapeutic options available to cancer patients. MicroRNA 21-5p (miR-21) has been shown to be upregulated in HCC, but the contribution of this oncomiR to the maintenance of tumorigenic phenotype in liver cancer remains poorly understood. We have developed potent and specific single-stranded oligonucleotide inhibitors of miR-21 (anti-miRNAs) and used them to interrogate dependency on miR-21 in a panel of liver cancer cell lines. Treatment with anti-miR-21, but not with a mismatch control anti-miRNA, resulted in significant derepression of direct targets of miR-21 and led to loss of viability in the majority of HCC cell lines tested. Robust induction of caspase activity, apoptosis, and necrosis was noted in anti-miR-21-treated HCC cells. Furthermore, ablation of miR-21 activity resulted in inhibition of HCC cell migration and suppression of clonogenic growth. To better understand the consequences of miR-21 suppression, global gene expression profiling was performed on anti-miR-21-treated liver cancer cells, which revealed striking enrichment in miR-21 target genes and deregulation of multiple growth-promoting pathways. Finally, in vivo dependency on miR-21 was observed in two separate HCC tumor xenograft models. In summary, these data establish a clear role for miR-21 in the maintenance of tumorigenic phenotype in HCC in vitro and in vivo.

IMPLICATIONS

miR-21 is important for the maintenance of the tumorigenic phenotype of HCC and represents a target for pharmacologic intervention.

Pluripotent stem cell miRNAs and metastasis in invasive breast cancer

BACKGROUND

The purpose of this study is to determine whether microRNA for pluripotent stem cells are also expressed in breast cancer and are associated with metastasis and outcome.

METHODS

We studied global microRNA profiles during differentiation of human embryonic stem cells (n =26) and in breast cancer patients (n = 33) and human cell lines (n = 35). Using in situ hybridization, we then investigated MIR302 expression in 318 untreated breast cancer patients (test cohort, n = 22 and validation cohort, n = 296). In parallel, using next-generation sequencing data from breast cancer patients (n = 684), we assessed microRNA association with stem cell markers. All statistical tests were two-sided.

RESULTS

In healthy tissues, the MIR302 (high)/MIR203 (low) asymmetry was exclusive for pluripotent stem cells. MIR302 was expressed in a small population of cancer cells within invasive ductal carcinoma, but not in normal breast (P < .001). Furthermore, MIR302 was expressed in the tumor cells together with stem cell markers, such as CD44 and BMI1. Conversely, MIR203 expression in 684 breast tumors negatively correlated with CD44 (Spearman correlation, Rho = -0.08, P = .04) and BMI1 (Rho = -0.11, P = .004), but positively correlated with differentiation marker CD24 (Rho = 0.15, P < .001). Primary tumors with lymph node metastasis had cancer cells showing scattered expression of MIR302 and widespread repression of MIR203. Finally, overall survival was statistically significantly shorter in patients with MIR302-positive cancer cells (P = .03).

CONCLUSIONS

In healthy tissues the MIR302(high)/MIR203(low) asymmetry was characteristic of embryonic and induced pluripotency. In invasive ductal carcinoma, the MIR302/MIR203 asymmetry was associated with stem cell markers, metastasis, and shorter survival.

Abstract 4787: Targeting miR-21 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains a significant unmet medical need with few therapeutic options available. Micro RNA 21 (miR-21) has been shown to be upregulated in HCC, however, contribution of this onco-miR to the maintenance of tumorigenic phenotype in liver cancer remains poorly understood. We have developed potent and specific single-stranded oligonucleotide inhibitors of miR-21 (anti-miR-21) and used them to interrogate dependency on miR-21 in a panel of 20 commercially available HCC cell lines in vitro. Upon lipid-mediated transfection, anti-miR-21, but not its mismatched (MM) control, caused significant de-repression of known direct targets of miR-21 (ANKRD46, DDAH1, RECK1) and inhibited survival of a large subset of HCC cell lines. Treatment of these sensitive HCC cell lines with anti-miR-21 resulted in dose- and time-dependent induction of caspase 3/7 activity. In contrast, non-responder HCC cell lines failed to significantly upregulate caspase activity and maintained viability in the presence of anti-miR compound. Further analysis of responder cell lines revealed robust induction of cell death, inhibition of cell migration and suppression of clonogenic growth upon treatment with miR-21 inhibitor. To better understand the consequences of miR-21 suppression in HCC, we carried out global gene expression profiling of anti-miR-21 treated sensitive liver cancer cells. Striking enrichment in miR-21 targets was noted among upregulated transcripts. Gene ontology analysis identified key cellular processes affected by miR-21 inhibition, including deregulation of metabolic pathways. In addition to the induction of direct miR-21 targets, cyclin H was found to be significantly downregulated upon miR-21 inhibition in the majority of responder cell lines. We hypothesize that inhibition of cyclin H expression, while an indirect effect of miR-21 suppression, could contribute to the activity of anti-miR-21 compounds. In summary, our data suggest that inhibition of miR-21 merits further investigation in the treatment of hepatocellular carcinoma.

Citation Format: Sonya Zabludoff, Timothy Wagenaar, Francisco Adrian, Charles Allerson, Heike Arlt, Raffaele Baffa, Bal Bhat, Hui Cao, Scott Davis, Carlos Garcia-Echeverria, Kathrin Heermeier, Shih-Min Huang, Lan Jiang, Eric Marcusson, Christiane Metz-Weidmann, Adam Pavlicek, Jack Pollard, Jennifer Rocnik, Sabine Scheidler, Chaomei Shi, Fangxian Sun, Tatiana Tolstykh, Qunyan Yu, Gang Zheng, Dmitri Wiederschain. Targeting miR-21 in hepatocellular carcinoma. [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 4787. doi:10.1158/1538-7445.AM2014-4787

Abstract 5448: PTK7 as a potential therapeutic target in ovarian cancer

The identification of proteins that selectively discriminate between tumor cells and normal adult cells allows for the specific targeting of diseased cells with antibody therapeutics. One such recently identified protein, PTK7, is an onco-fetal membrane protein which exhibits limited expression and function in adults. PTK7 was identified as a member of the RTK super family but lacks a functional kinase domain. Normally, PTK7 is expressed early in development and its loss is associated with severe defects in neural tube closure and sensory hair cell bundle formation. Functionally, little is known about the signaling involving PTK7, but it has been linked to both the canonical and noncanonical WNT pathways. Recently, PTK7 expression has been shown to be upregulated in a number of cancers including: ovarian, melanoma, leukemia, lung, pancreatic, colon, renal and breast. In vitro and in vivo studies support a role in regulating angiogenesis, invasion & survival. To further validate PTK7 as a potential cancer target that may be required for tumor maintenance and progression, we analyzed the expression of PTK7 in normal and tumor samples, and validated an in vitro and in vivo role of PTK7 on cell growth in ovarian cancer cell lines using both genetic tools and polyclonal antibodies. Silencing PTK7 with stably expressed inducible shRNAs is shown to inhibit the growth of ovarian cancer cell lines in vitro and to lead to delayed tumor growth upon PTK7 knockdown in murine tumor xenograft models. Further supporting the role of PTK7 as a potential antibody target, polyclonal antibodies to PTK7 are shown to inhibit the growth of SKOV3 and OVCAR8 cells in vitro. Although 4 human antibodies derived from phage display failed to inhibit in vitro cell growth, these results suggest that functionally blocking PTK7 may lead to the inhibition of ovarian tumor growth and is a potential target for antibody therapies.

Citation Format: Zhihu Ding, Amanda Lennon, Keli Perron, David Harper, Hui Su, Meredith Wolfram, Joshua Murtie, Stuart Licht, Jason Pinckney, Helene Simonds-Mannes, Kimberly Bishop, Julie-Ann Gavigan, Dinesh Bangari, Maureen Magnay, William Weber, David Reczek, William Brondyk, Vicky Drewett, Marc Trombe, Dietmar Hoffmann, Raffaele Baffa, Serena Silver, Victoria Richon, Christopher Winter, Venkat Reddy, Richard C. Gregory. PTK7 as a potential therapeutic target in ovarian cancer. [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 5448. doi:10.1158/1538-7445.AM2014-5448

Transcribed ultraconserved noncoding RNAs (T-UCR) are involved in Barrett's esophagus carcinogenesis

Barrett's esophagus (BE) involves a metaplastic replacement of native esophageal squamous epithelium (Sq) by columnar-intestinalized mucosa, and it is the main risk factor for Barrett-related adenocarcinoma (BAc). Ultra-conserved regions (UCRs) are a class non-coding sequences that are conserved in humans, mice and rats. More than 90% of UCRs are transcribed (T-UCRs) in normal tissues, and are altered at transcriptional level in tumorigenesis. To identify the T-UCR profiles that are dysregulated in Barrett's mucosa transformation, microarray analysis was performed on a discovery set of 51 macro-dissected samples obtained from 14 long-segment BE patients. Results were validated in an independent series of esophageal biopsy/surgery specimens and in two murine models of Barrett's esophagus (i.e. esophagogastric-duodenal anastomosis). Progression from normal to BE to adenocarcinoma was each associated with specific and mutually exclusive T-UCR signatures that included up-regulation of uc.58-, uc.202-, uc.207-, and uc.223- and down-regulation of uc.214+. A 9 T-UCR signature characterized BE versus Sq (with the down-regulation of uc.161-, uc.165-, and uc.327-, and the up-regulation of uc.153-, uc.158-, uc.206-, uc.274-, uc.472-, and uc.473-). Analogous BE-specific T-UCR profiles were shared by human and murine lesions. This study is the first demonstration of a role for T-UCRs in the transformation of Barrett's mucosa.

Decorin induces mitophagy in breast carcinoma cells via peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitostatin

Tumor cell mitochondria are key biosynthetic hubs that provide macromolecules for cancer progression and angiogenesis. Soluble decorin protein core, hereafter referred to as decorin, potently attenuated mitochondrial respiratory complexes and mitochondrial DNA (mtDNA) in MDA-MB-231 breast carcinoma cells. We found a rapid and dynamic interplay between peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and the decorin-induced tumor suppressor gene, mitostatin. This interaction stabilized mitostatin mRNA with concurrent accumulation of mitostatin protein. In contrast, siRNA-mediated abrogation of PGC-1α-blocked decorin-evoked stabilization of mitostatin. Mechanistically, PGC-1α bound MITOSTATIN mRNA to achieve rapid stabilization. These processes were orchestrated by the decorin/Met axis, as blocking the Met-tyrosine kinase or knockdown of Met abrogated these responses. Furthermore, depletion of mitostatin blocked decorin- or rapamycin-evoked mitophagy, increased vascular endothelial growth factor A (VEGFA) production, and compromised decorin-evoked VEGFA suppression. Collectively, our findings underscore the complexity of PGC-1α-mediated mitochondrial homeostasis and establish mitostatin as a key regulator of tumor cell mitophagy and angiostasis.

Abstract C242: A phase 1/1b dose escalation study of iniparib as a single agent and in combination with gemcitabine/carboplatin in patients with advanced solid tumors

Background: Iniparib (I) is a novel anticancer agent initially thought to be a poly (ADP-ribose) polymerase (PARP) inhibitor. Recent preclinical data suggest that iniparib does not inhibit PARP at pharmacologically-relevant concentrations. The initial Phase 1 did not identify any dose limiting toxicity (DLT) and the dose of 5.6 mg/kg used in further development was based on a PK/PD model for PARP inhibition. This new Phase 1 study was designed to determine a maximum tolerated dose (MTD) based on DLT occurrence for single agent iniparib and in combination with gemcitabine and carboplatin (GC).

Patients and Methods: Patients with advanced cancer and ECOG performance status (PS) 0-2 with no standard therapeutic option or for whom GC could be considered an adequate treatment were enrolled in this trial. In the Phase 1 portion, patients received escalating doses of single agent iniparib starting at 15 mg/kg in a 3+3 design. In the Phase 1b, two different regimens of GC and iniparib were evaluated (GC2+I: carboplatin AUC2, gemcitabine 1,000 mg/m2 and iniparib on Days 1 and 8 every 21 days; and GC5+I: carboplatin AUC5 on Day 1, gemcitabine at 1,000 mg/m2 and iniparib both on Days 1 and 8 in a 21-day cycle). At the MTD, the cohort was expanded by 12 patients. Safety, pharmacokinetics, pharmacodynamics, and antitumor effects were also evaluated.

Results: Of the 59 patients (M/F= 18/41; ECOG 0/1-2=21/38) enrolled in this study, 29 received single agent iniparib (15 mg/kg=3; 20 mg/kg=16; 26 mg/kg=10); 23 received GC2+I (15 mg/kg=3; 20 mg/kg=20) and 7 were treated in the GC5+I arm at 15 mg/kg. DLT in the phase 1 was G3 transient increase in blood pressure during the iniparib infusion in 4 patients treated at 26 mg/kg. Nine patients at 20 mg/kg (5 in Phase 1 and 4 in Phase 1b) experienced also transient non-DLT hypertension. In most cases HTN was managed by interrupting the infusion; infusions were completed after blood pressure normalization. No patient was discontinued due to it. DLT for GC2+I was G4 thrombocytopenia in 3 patients. GC5+I at 15 mg/kg was considered non-tolerable due to G4 hematological toxicity in 2/5 patients. One ovarian cancer patient treated with iniparib single agent at 26 mg/kg for longer than 18 months had a durable (9 months) partial response (PR). Ten PRs were recorded in combination with GC.

Conclusions: The MTD of iniparib single agent and in combination with GC2 is 20 mg/kg weekly. Hypertension during the infusion has been identified as a characteristic DLT. The MTD of GC5+I is below 15mg/kg of iniparib weekly due to hematological toxicity. The GC2+I regimen demonstrated manageable tolerability.

ClinicalTrials.gov identifier: NCT01455532

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C242.

Citation Format: Monica Mita, Raffaele Baffa, Eric Charpentier, Craig A. Lockhart, John C. Morris, Olivier Rixe, John Sarantopoulos, Ramesh Ramanathan. A phase 1/1b dose escalation study of iniparib as a single agent and in combination with gemcitabine/carboplatin in patients with advanced solid tumors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C242.

MicroRNA dysregulation in esophageal neoplasia: the biological rationale for novel therapeutic options

While the phenotypic changes involved in the esophageal oncogenic "cascade" are now well established, the molecular profiling of this pathway remains unreliable. Our understanding of the molecular dysregulations underlying the development/progression of cancer has recently been expanded by the characterization of a new class of small, noncoding RNA gene products, the microRNAs (or miRNAs). These "endogenous silencers" target a large number of genes, functioning as tumor suppressors or tumor promoters, depending on the activity of the targeted genes. In esophageal cancer, miRNA dysregulation plays a significant part in the molecular oncogenic pathway, in cancer prognosis, and in patients' responsiveness to neo-adjuvant and adjuvant therapies. In addition to these valuable features, miRNAs have been proposed as innovative therapeutics per se and as plausible biological targets in new treatment strategies.

Advanced precancerous lesions within the GI tract: the molecular background

The mainstream carcinogenic processes involved within the gastrointestinal tract are characterized by phenotypic multistep progression cascades that eventually result in full-blown cancers. In this scenario, the understanding of the molecular dysregulations underlying the precancerous lesions is increasing but still remains incomplete. However, in recent years, the enthusiastic rise of innovative technologies (i.e., next-generation sequencing, high-throughput microarray analysis, mass spectrometry based proteomics) and the unexpected discovery of new classes of biomarkers (i.e., miRNA, long-noncoding RNAs) prompted new strength in the exploration of the accurate and comprehensive molecular characterization of premalignant and malignant neoplastic lesions. The challenge ahead lies in the reliable identification of disease progression-specific targets to enable molecular testing in the clinical management of the secondary prevention of gastrointestinal cancers.

Role of miRNA in distinguishing primary brain tumors from secondary tumors metastatic to the brain

Cancer is the result of complex processes that involve multiple molecular alterations. The understanding of such complexity has been improved by the advent of a new class of small, noncoding RNA gene products known as microRNAs (or miRNAs). miRNAs play an essential role in cancer development and progression by modulating gene expression binding to target mRNA, causing either mRNA degradation or translation inhibition. Several studies have shown that miRNAs can act either as tumor suppressors or as oncogenes, and that measurement of miRNA expression in malignancies may have diagnostic and prognostic implications. Beyond these valuable features, miRNAs could be potentially used in the future as innovative and targeted therapeutics. Recent in vitro and expression profiling studies have identified that specific miRNAs are directly involved in brain carcinogenesis and in the metastatic process. This review focuses on metastasis-related miRNAs and on the role of miRNAs in distinguishing between primary and metastatic brain tumors. In clinical practice, miRNAs could represent a promising new class of cancer biomarkers in the diagnosis and management of brain neoplastic lesions.

Mitostatin is down-regulated in human prostate cancer and suppresses the invasive phenotype of prostate cancer cells

MITOSTATIN, a novel putative tumor suppressor gene induced by decorin overexpression, is expressed in most normal human tissues but is markedly down-regulated in advanced stages of mammary and bladder carcinomas. Mitostatin negatively affects cell growth, induces cell death and regulates the expression and activation levels of Hsp27. In this study, we demonstrated that ectopic expression of Mitostatin in PC3, DU145, and LNCaP prostate cancer cells not only induced a significant reduction in cell growth, but also inhibited migration and invasion. Moreover, Mitostatin inhibited colony formation in soft-agar of PC3 and LNCaP cells as well as tumorigenicity of LNCaP cells in nude mice. Conversely, targeting endogenous Mitostatin by siRNA and anti-sense strategies in PC3 and DU145 prostate cancer cells enhanced the malignant phenotype in both cell lines. In agreement of these anti-oncogenic roles, we discovered that Mitostatin was absent in ∼35% (n = 124) of prostate tumor samples and its overall reduction was associated with advanced cancer stages. Collectively, our findings indicate that MITOSTATIN may acts as a tumor suppressor gene in prostate cancer and provide a novel cellular and molecular mechanism to be further exploited and deciphered in our understanding of prostate cancer progression.

MicroRNA expression profiling in human Barrett's carcinogenesis

Barrett's esophagus (BE) is characterized by the native stratified squamous epithelium (N) lining the esophagus being replaced by a columnar epithelium with intestinal differentiation (Barrett's mucosa; BM). BM is considered as the main risk factor for esophageal adenocarcinoma (Barrett's adenocarcinoma; BAc). MicroRNAs (miRNAs) are a class of small noncoding RNAs that control gene expression by targeting messenger RNAs and they are reportedly dysregulated in BM. To test the hypothesis that a specific miRNA expression signature characterizes BM development and progression, we performed miRNA microarray analysis comparing native esophageal mucosa with all the phenotypic lesions seen in the Barrett's carcinogenic process. Specimens were collected from 14 BE patients who had undergone esophagectomy, including: 14 with N, 14 with BM, 7 with low-grade intraepithelial neoplasia, 5 with high-grade intra-epithelial neoplasia and 11 with BAc. Microarray findings were further validated by quantitive real-time polymerase chain reaction and in situ hybridization analyses using a different series of consecutive cases (162 biopsy samples and 5 esophagectomies) of histologically proven, long-segment BE. We identified a miRNA signature of Barrett's carcinogenesis consisting of an increased expression of 6 miRNAs and a reduced expression of 7 miRNAs. To further support these results, we investigated target gene expression using the Oncomine database and/or immunohistochemical analysis. We found that target gene expression correlated significantly with miRNA dysregulation. Specific miRNAs are directly involved in BE progression to cancer. miRNA profiling significantly expands current knowledge on the molecular history of Barrett's carcinogenesis, also identifying molecular markers of cancer progression.

Trichoplein/mitostatin regulates endoplasmic reticulum-mitochondria juxtaposition

Trichoplein/mitostatin (TpMs) is a keratin-binding protein that partly colocalizes with mitochondria and is often downregulated in epithelial cancers, but its function remains unclear. In this study, we report that TpMs regulates the tethering between mitochondria and endoplasmic reticulum (ER) in a Mitofusin 2 (Mfn2)-dependent manner. Subcellular fractionation and immunostaining show that TpMs is present at the interface between mitochondria and ER. The expression of TpMs leads to mitochondrial fragmentation and loosens tethering with ER, whereas its silencing has opposite effects. Functionally, the reduced tethering by TpMs inhibits apoptosis by Ca(2+)-dependent stimuli that require ER-mitochondria juxtaposition. Biochemical and genetic evidence support a model in which TpMs requires Mfn2 to modulate mitochondrial shape and tethering. Thus, TpMs is a new regulator of mitochondria-ER juxtaposition.

Reprogramming of miRNA networks in cancer and leukemia

We studied miRNA profiles in 4419 human samples (3312 neoplastic, 1107 nonmalignant), corresponding to 50 normal tissues and 51 cancer types. The complexity of our database enabled us to perform a detailed analysis of microRNA (miRNA) activities. We inferred genetic networks from miRNA expression in normal tissues and cancer. We also built, for the first time, specialized miRNA networks for solid tumors and leukemias. Nonmalignant tissues and cancer networks displayed a change in hubs, the most connected miRNAs. hsa-miR-103/106 were downgraded in cancer, whereas hsa-miR-30 became most prominent. Cancer networks appeared as built from disjointed subnetworks, as opposed to normal tissues. A comparison of these nets allowed us to identify key miRNA cliques in cancer. We also investigated miRNA copy number alterations in 744 cancer samples, at a resolution of 150 kb. Members of miRNA families should be similarly deleted or amplified, since they repress the same cellular targets and are thus expected to have similar impacts on oncogenesis. We correctly identified hsa-miR-17/92 family as amplified and the hsa-miR-143/145 cluster as deleted. Other miRNAs, such as hsa-miR-30 and hsa-miR-204, were found to be physically altered at the DNA copy number level as well. By combining differential expression, genetic networks, and DNA copy number alterations, we confirmed, or discovered, miRNAs with comprehensive roles in cancer. Finally, we experimentally validated the miRNA network with acute lymphocytic leukemia originated in Mir155 transgenic mice. Most of miRNAs deregulated in these transgenic mice were located close to hsa-miR-155 in the cancer network.

The insulin-like growth factor receptor I promotes motility and invasion of bladder cancer cells through Akt- and mitogen-activated protein kinase-dependent activation of paxillin

The insulin-like growth factor receptor I (IGF-IR) plays an essential role in transformation by promoting cell growth and protecting cancer cells from apoptosis. Aberrant IGF-IR signaling is implicated in several types of tumors, including carcinomas of the lung, breast, prostate, pancreas, liver, and colon. However, the contribution of the IGF-IR to the development of the transformed phenotype in urothelial cells has not been clearly established. In this study we demonstrated that the IGF-IR is overexpressed in invasive bladder cancer tissues compared with nonmalignant controls. We have investigated the role of the IGF-IR in bladder cancer by using urothelial carcinoma-derived 5637 and T24 cells. Although activation of the IGF-IR did not appreciably affect their growth, it did promote migration and stimulate in vitro wound closure and invasion. These effects required the activation of the Akt and Mitogen-activated protein kinase (MAPK) pathways as well as IGF-I-induced Akt- and MAPK-dependent phosphorylation of paxillin, which relocated at dynamic focal adhesions and was necessary for promoting motility in bladder cancer cells. Our results provide the first evidence for a role of the IGF-IR in motility and invasion of bladder cancer cells and support the hypothesis that the IGF-IR may play a critical role in the establishment of the invasive phenotype in urothelial neoplasia. Thus, the IGF-IR may also serve as a novel biomarker for bladder cancer.

Abstract 5057: The insulin-like growth factor receptor I promotes motility and invasion of bladder cancer cells through Akt- and MAPK-dependent activation of paxillin

The insulin-like growth factor receptor I (IGF-IR) plays an essential role in transformation by promoting cell growth and protecting cancer cells from apoptosis. Aberrant IGF-IR signaling is implicated in several types of tumors, including carcinomas of the lung, breast, prostate, pancreas, liver and colon. However, whether the IGF-IR contributes to the transforming phenotype of urothelial cells has not been clearly established but recent data suggest that the IGF-IR is over-expressed in bladder cancer.

In this study we demonstrated by immunohistochemical analysis that the IGF-IR is over-expressed in invasive bladder cancer (T3/T4) tissues compared to non-malignant controls. We have also characterized the mechanism of action of the IGF-IR in cancer urothelial cells using urothelial carcinoma-derived 5637 and T24 cells. Although activation of the IGF-IR did not appreciably affect their growth, it did promote migration and stimulate in vitro wound closure and invasion through extracellular matrix. These effects required the activation of the Akt and MAPK pathways and IGF-I induced Akt- and MAPK-dependent phosphorylation of paxillin, which relocated at dynamic focal adhesions at the protruding edge of migrating urothelial cancer cells. Using siRNA strategies we also demonstrated that paxillin was necessary for promoting IGF-I-mediated motility and invasion in bladder cancer cells.

In conclusion, our results provide the first evidence for a role of the IGF-IR in motility and invasion of bladder cancer cells, and support the hypothesis that the IGF-IR may play a critical role in the establishment of the invasive phenotype in urothelial neoplasia. The IGF-IR could represent a novel molecular target in bladder cancer and could also serve as a novel tumor biomarker for diagnosis and possibly prognosis of bladder tumors.

This work has been supported by the Benjamin Perkins Bladder Cancer Fund, the Martin Greitzer Fund and National Institutes of Health Grants RO1 DK068419 (A.M.) and RO1 CA39481 and RO1 CA047282 (R.V.I.).

§Present address: Medimmune, One Medimmune Way, Gaithersburg, MD 20878

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5057.

MicroRNA expression profiling of human metastatic cancers identifies cancer gene targets

Small non-coding microRNAs (miRNAs) contribute to cancer development and progression, and are differentially expressed in normal tissues and cancers. However, the specific role of miRNAs in the metastatic process is still unknown. To seek a specific miRNA expression signature characterizing the metastatic phenotype of solid tumours, we performed a miRNA microarray analysis on 43 paired primary tumours (ten colon, ten bladder, 13 breast, and ten lung cancers) and one of their related metastatic lymph nodes. We identified a metastatic cancer miRNA signature comprising 15 overexpressed and 17 underexpressed miRNAs. Our results were confirmed by qRT-PCR analysis. Among the miRNAs identified, some have a well-characterized association with cancer progression, eg miR-10b, miR-21, miR-30a, miR-30e, miR-125b, miR-141, miR-200b, miR-200c, and miR-205. To further support our data, we performed an immunohistochemical analysis for three well-defined miRNA gene targets (PDCD4, DHFR, and HOXD10 genes) on a small series of paired colon, breast, and bladder cancers, and one of their metastatic lymph nodes. We found that the immunohistochemical expression of these targets significantly follows the corresponding miRNA deregulation. Our results suggest that specific miRNAs may be directly involved in cancer metastasis and that they may represent a novel diagnostic tool in the characterization of metastatic cancer gene targets.

Cyclin D1 splice variants: polymorphism, risk, and isoform-specific regulation in prostate cancer

PURPOSE

Alternative CCND1 splicing results in cyclin D1b, which has specialized, protumorigenic functions in prostate not shared by the cyclin D1a (full length) isoform. Here, the frequency, tumor relevance, and mechanisms controlling cyclin D1b were challenged.

EXPERIMENTAL DESIGN

First, relative expression of both cyclin D1 isoforms was determined in prostate adenocarcinomas. Second, relevance of the androgen axis was determined. Third, minigenes were created to interrogate the role of the G/A870 polymorphism (within the splice site), and findings were validated in primary tissue. Fourth, the effect of G/A870 on cancer risk was assessed in two large case-control studies.

RESULTS

Cyclin D1b is induced in tumors, and a significant subset expressed this isoform in the absence of detectable cyclin D1a. Accordingly, the isoforms showed noncorrelated expression patterns, and hormone status did not alter splicing. Whereas G/A870 was not independently predictive of cancer risk, A870 predisposed for transcript-b production in cells and in normal prostate. The influence of A870 on overall transcript-b levels was relieved in tumors, indicating that aberrations in tumorigenesis likely alter the influence of the polymorphism.

CONCLUSIONS

These studies reveal that cyclin D1b is specifically elevated in prostate tumorigenesis. Cyclin D1b expression patterns are distinct from that observed with cyclin D1a. The A870 allele predisposes for transcript-b production in a context-specific manner. Although A870 does not independently predict cancer risk, tumor cells can bypass the influence of the polymorphism. These findings have major implications for the analyses of D-cyclin function in the prostate and provide the foundation for future studies directed at identifying potential modifiers of the G/A870 polymorphism.

MicroRNA expression profiling of male breast cancer

Introduction

MicroRNAs (miRNAs) are a class of small noncoding RNAs that control gene expression by targeting mRNAs and triggering either translation repression or RNA degradation. Their aberrant expression may be involved in human diseases, including cancer. To test the hypothesis that there is a specific miRNA expression signature which characterizes male breast cancers, we performed miRNA microarray analysis in a series of male breast cancers and compared them with cases of male gynecomastia and female breast cancers.

Methods

Paraffin blocks were obtained at the Department of Pathology of Thomas Jefferson University from 28 male patients including 23 breast cancers and five cases of male gynecomastia, and from 10 female ductal breast carcinomas. The RNA harvested was hybridized to miRNA microarrays (~1,100 miRNA probes, including 326 human and 249 mouse miRNA genes, spotted in duplicate). To further support the microarray data, an immunohistochemical analysis for two specific miRNA gene targets (HOXD10 and VEGF) was performed in a small series of male breast carcinoma and gynecomastia samples.

Results

We identified a male breast cancer miRNA signature composed of a large portion of underexpressed miRNAs. In particular, 17 miRNAs with increased expression and 26 miRNAs with decreased expression were identified in male breast cancer compared with gynecomastia. Among these miRNAs, some had well-characterized cancer development association and some showed a deregulation in cancer specimens similar to the one previously observed in the published signatures of female breast cancer. Comparing male with female breast cancer miRNA expression signatures, 17 significantly deregulated miRNAs were observed (four overexpressed and 13 underexpressed in male breast cancers). The HOXD10 and VEGF gene immunohistochemical expression significantly follows the corresponding miRNA deregulation.

Conclusions

Our results suggest that specific miRNAs may be directly involved in male breast cancer development and that they may represent a novel diagnostic tool in the characterization of specific cancer gene targets.

Proepithelin is an autocrine growth factor for bladder cancer

The growth factor proepithelin functions as an important regulator of proliferation and motility. Proepithelin is overexpressed in a great variety of cancer cell lines and clinical specimens of breast, ovarian and renal cancer, as well as glioblastomas. Using recombinant proepithelin on 5637 transitional cell carcinoma-derived cells, we have shown previously that proepithelin plays a critical role in bladder cancer by promoting motility of bladder cancer cells. In this study, we used the ONCOMINE database and gene microarray analysis tool to analyze proepithelin expression in several bladder cancer microarray studies. We found a statistically significant increase in proepithelin messenger RNA expression in bladder cancers vis-à-vis non-neoplastic tissues, and this was associated with pathologic and prognostic parameters. Targeted downregulation of proepithelin in T24 transitional carcinoma cells with small hairpin RNA inhibited both Akt and mitogen-activated protein kinase pathways, severely reduced the ability of T24 cells to proliferate in the absence of serum and inhibited migration, invasion and wound healing. In support of these in vitro results, we discovered that proepithelin expression was significantly upregulated in invasive bladder cancer tissues compared with normal urothelium. In addition, proepithelin was secreted in the urine, where it was detectable by immunoblotting and enzyme-linked immunosorbent assay. Collectively, these results support the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and progression of bladder cancer and suggest that proepithelin may prove a novel biomarker for the diagnosis and prognosis of bladder neoplasms.

Proepithelin regulates prostate cancer cell biology by promoting cell growth, migration, and anchorage-independent growth

The growth factor proepithelin has recently emerged as an important regulator of transformation in several physiological and pathological systems. In this study, we determined the biological roles of proepithelin in prostate cancer cells using purified human recombinant proepithelin as well as proepithelin-depletion strategies. Proepithelin promoted the migration of androgen-dependent and -independent human prostate cancer cells; androgen-independent DU145 cells were the more responsive. In these cells, proepithelin additionally stimulated wound closure, invasion, and promotion of cell growth in vitro. These effects required the activation of both the Akt and mitogen-activated protein kinase pathways. We have analyzed proepithelin expression levels in different available prostate cancer microarray studies using the Oncomine database and found a statistically significant increase in proepithelin mRNA expression levels in prostate cancers compared with nonneoplastic controls. Notably, depletion of endogenous proepithelin by siRNA and antisense strategies impaired the ability of DU145 cells to grow and migrate after serum withdrawal and inhibited anchorage-independent growth. Our results provide the first evidence for a role of proepithelin in stimulating the migration, invasion, proliferation, and anchorage-independent growth of prostate cancer cells. This study supports the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and initial progression of prostate cancer. Furthermore, proepithelin may prove to be a useful clinical marker for the diagnosis of prostate tumors.

MITOSTATIN, a putative tumor suppressor on chromosome 12q24.1, is downregulated in human bladder and breast cancer

Allelic deletions on human chromosome 12q24 are frequently reported in a variety of malignant neoplasms, indicating the presence of a tumor suppressor gene(s) in this chromosomal region. However, no reasonable candidate has been identified so far. In this study, we report the cloning and functional characterization of a novel mitochondrial protein with tumor suppressor activity, henceforth designated MITOSTATIN. Human MITOSTATIN was found within a 3.2-kb transcript which encoded a ~62 kDa, ubiquitously-expressed protein with little homology to any known protein. We found homozygous deletions and mutations of MITOSTATIN gene in ~5% and ~11% of various cancer-derived cells and solid tumors, respectively. When transiently over-expressed, MITOSTATIN inhibited colony formation, tumor cell growth and was pro-apoptotic, all features shared by established tumor suppressor genes. We discovered a specific link between MITOSTATIN over-expression and down-regulation of Hsp27. Conversely MITOSTATIN knock-down cells showed an increase in cell growth and cell survival rates. Finally, MITOSTATIN expression was significantly reduced in primary bladder and breast tumors, and its reduction was associated with advanced tumor stages. Our findings support the hypothesis that MITOSTATIN has many hallmarks of a classical tumor suppressor in solid tumors and may play an important role in cancer development and progression.

An antimetastatic role for decorin in breast cancer

Decorin, a member of the small leucine-rich proteoglycan gene family, down-regulates members of the ErbB receptor tyrosine kinase family and attenuates their signaling, leading to growth inhibition. We investigated the effects of decorin on the growth of ErbB2-overexpressing mammary carcinoma cells in comparison with AG879, an established ErbB2 kinase inhibitor. Cell proliferation and anchorage-independent growth assays showed that decorin was a potent inhibitor of breast cancer cell growth and a pro-apoptotic agent. When decorin and AG879 were used in combination, the inhibitory effect was synergistic in proliferation assays but only additive in both colony formation and apoptosis assays. Active recombinant human decorin protein core, AG879, or a combination of both was administered systemically to mice bearing orthotopic mammary carcinoma xenografts. Primary tumor growth and metabolism were reduced by approximately 50% by both decorin and AG879. However, no synergism was observed in vivo. Decorin specifically targeted the tumor cells and caused a significant reduction of ErbB2 levels in the tumor xenografts. Most importantly, systemic delivery of decorin prevented metastatic spreading to the lungs, as detected by novel species-specific DNA detection and quantitative assays. In contrast, AG879 failed to have any effect. Our data support a role for decorin as a powerful and effective therapeutic agent against breast cancer due to its inhibition of both primary tumor growth and metastatic spreading.

Fez1/Lzts1-deficient mice are more susceptible to N-butyl-N-(4-hydroxybutil) nitrosamine (BBN) carcinogenesis

FEZ1/LZTS1 is a tumor suppressor gene that is frequently altered in human cancers of different histotypes. We have reported previously that LZTS1 is downregulated in high-grade bladder cancer and that its restoration suppresses tumorigenicity in urothelial carcinoma cells. To further investigate the role of LZTS1 in the development of bladder cancer, we utilized heterozygous and nullizygous Lzts1 mice in a chemically induced carcinogenesis model. Fifty-eight mice consisting of 25 Lzts1(+/+), 17 Lzts1(+/-) and 16 Lzts1(-/-) were treated with N-butyl-N-(4-hydroxybutil) nitrosamine (BBN). Results showed that there was a significant increase in neoplastic lesions in the Lzts1(+/-) (82.3%) and Lzts1(-/-) (93.8%) versus Lzts1(+/+) (8.0%) mice after BBN treatment. No difference in cancer incidence between Lzts1(+/-) and Lzts1(-/-) was observed. Collectively, these findings indicate that loss of one or both LZTS1 alleles hampers the normal defenses of urothelial cells against carcinogens, favoring bladder cancer development. Therefore, LZTS1 may become an excellent target for gene therapy in advanced bladder carcinoma.

Micro-RNA profiling in kidney and bladder cancers

OBJECTIVES

Micro-RNAs are a group of small noncoding RNAs with modulator activity of gene expression. Recently, micro-RNA genes were found abnormally expressed in several types of cancers. To study the role of the micro-RNAs in human kidney and bladder cancer, we analyzed the expression profile of 245 micro-RNAs in kidney and bladder primary tumors.

METHODS AND MATERIALS

A total of 27 kidney specimens (20 carcinomas, 4 benign renal tumors, and 3 normal parenchyma) and 27 bladder specimens (25 urothelial carcinomas and 2 normal mucosa) were included in the study. Total RNA was used for hybridization on an oligonucleotide microchip for micro-RNA profiling developed in our laboratories. This microchip contains 368 probes in triplicate, corresponding to 245 human and mouse micro-RNA genes.

RESULTS

A set of 4 human micro-RNAs (miR-28, miR-185, miR-27, and let-7f-2) were found significantly up-regulated in renal cell carcinoma (P < 0.05) compared to normal kidney. Human micro-RNAs miR-223, miR-26b, miR-221, miR-103-1, miR-185, miR-23b, miR-203, miR-17-5p, miR-23a, and miR-205 were significantly up-regulated in bladder cancers (P < 0.05) compared to normal bladder mucosa. Of the kidney cancers studied, there was no differential micro-RNA expression across various stages, whereas with increasing tumor-nodes-metastasis staging in bladder cancer, miR-26b showed a moderate decreasing trend (P = 0.082).

CONCLUSIONS

Our results show that different micro-RNAs are deregulated in kidney and bladder cancer, suggesting the involvement of these genes in the development and progression of these malignancies. Further studies are needed to clarify the role of micro-RNAs in neoplastic transformation and to test the potential clinical usefulness of micro-RNAs microarrays as diagnostic and prognostic tool.

Targeted therapies in the management of metastatic bladder cancer

The management of metastatic urothelial carcinoma (UC) of the bladder is a common and complex clinical challenge. Despite the fact that UC is one of the most frequent tumors in the population, long term survival for metastatic disease remains low, and chemotherapy is curative for only a small minority of patients. UC is genetically heterogeneous, and it is surrounded by a complex tissue microenvironment. The problems of clinical practice in the field of metastatic bladder cancer have begun to stimulate translational research. Advances in the understanding of the molecular biology of urothelial cancer continue to contribute to the identification of molecular pathways upon which new therapeutic approaches can be targeted. New agents and strategies have recently been developed which can direct the most appropriate choice of treatment for advanced disease. A review of literature published on the targeted therapy for metastatic bladder cancer is presented, focusing on the molecular pathways shut down by the new therapeutic agents.

Fez1/Lzts1 absence impairs Cdk1/Cdc25C interaction during mitosis and predisposes mice to cancer development

The FEZ1/LZTS1 (LZTS1) protein is frequently downregulated in human cancers of different histotypes. LZTS1 is expressed in normal tissues, and its introduction in cancer cells inhibits cell growth and suppresses tumorigenicity, owing to an accumulation of cells in G2/M. Here, we define its role in cell cycle regulation and tumor progression by generating Lzts1 knockout mice. In Lzts1(-/-) mouse embryo fibroblasts (MEFs), Cdc25C degradation was increased during M phase, resulting in decreased Cdk1 activity. As a consequence, Lzts1(-/-) MEFs showed accelerated mitotic progression, resistance to taxol- and nocodazole-induced M phase arrest, and improper chromosome segregation. Accordingly, Lzts1 deficiency was associated with an increased incidence of both spontaneous and carcinogen-induced cancers in mice.

Molecular genetics of prostate cancer: clinical translational opportunities

Prostate cancer (PC) development reflects a complex sequence of biologic and molecular events. Several inheritable and somatic genetic changes have been identified. The knowledge of the molecular basis of PC can improve our understanding of the causes of this common cancer and provide information on prognosis and treatment. To date, however, no molecular studies have yet yielded consistent information that is ready to be incorporated into clinical practice. We reviewed the current literature on the molecular biology of prostate cancer and analyzed different potential tumor markers according to the classical concepts of oncogenes, suppressor genes, and the more modern concepts of genes involved in detoxification or inflammatory pathways of cancer progression. This review aims to identify trends in PC research and suggests potential clinical applications for diagnosis, prognosis, prevention and treatment.

Chromosomal deletions in bladder cancer: shutting down pathways

Bladder cancer is one of the most common cancers in the world, leading to approximately 145,000 deaths annually. Bladder cancer is typically managed by surgical removal of the tumor; however, the recurrence rate is disappointingly very high, often requiring systemic chemotherapy. Improvement in the diagnosis and prognosis of bladder cancer will only come from a comprehensive understanding of the genetic factors that lead to its development. In this review, we focus on the chromosomal deletions that contribute to the downregulation of tumor suppressor pathways in bladder cancer. Chromosomal deletions are not a random event, since bladder cancer progression has been associated with specific chromosomal deletions and this progression correlates with specific stages of tumor development. The most commonly found chromosomal deletion in all stages of bladder cancer involves deletions in chromosome 9, resulting in the loss of three genes encoding proteins that activate the Rb and p53 tumor suppressors. Additionally, chromosome 9 harbors the TSC1 tumor suppressor which downregulates the well-known anti-apoptotic Akt/mTOR pathway. Hence, deletions on one chromosome may have a crucial influence on the initial steps in tumor development. Other deletions targeting the tumor suppressors Rb, p53, FHIT and LZTS1 occur at later stages of tumor development. Considering the central importance of these tumor suppressor pathways in the formation and evolution of tumors, the time has come to evaluate available drugs in bladder cancer that target the positive regulators of these pathways.

Proepithelin promotes migration and invasion of 5637 bladder cancer cells through the activation of ERK1/2 and the formation of a paxillin/FAK/ERK complex

The growth factor proepithelin (also known as progranulin, acrogranin, PC-derived growth factor, or granulin-epithelin precursor) is a secreted glycoprotein that functions as an important regulator of cell growth, migration, and transformation. Proepithelin is overexpressed in a great variety of cancer cell lines and clinical specimens of breast, ovarian, and renal cancer as well as glioblastomas. In this study, we have investigated the effects of proepithelin on bladder cancer cells using human recombinant proepithelin purified to homogeneity from 293-EBNA cells. Although proepithelin did not appreciably affect cell growth, it did promote migration of 5637 bladder cancer cells and stimulate in vitro wound closure and invasion. These effects required the activation of the mitogen-activated protein kinase pathway and paxillin, which upon proepithelin stimulation formed a complex with focal adhesion kinase and active extracellular signal-regulated kinase. Our results provide the first evidence for a role of proepithelin in stimulating migration and invasion of bladder cancer cells, and support the hypothesis that this growth factor may play a critical role in the establishment of the invasive phenotype.

Molecular genetics of bladder cancer: targets for diagnosis and therapy

Transitional cell carcinoma of the bladder is a common tumor. While most patients presenting superficial disease can be expected to do well following treatment, still many patients will return to our office with muscle invasive and metastatic disease. Survival in advanced bladder cancer is less than 50%. Tumors of similar histologic grade and stage have variable behavior, suggesting that genetic alterations must be present to explain the diverse behavior of bladder cancer. It is hoped that through the study of the subtle genetic alterations in bladder cancer, important prognostic and therapeutic targets can be exploited. Many new diagnostic tests and gene therapy approaches rely on the identification and targeting of these unique genetic alterations. A review of literature published on the molecular genetics of bladder cancer from 1970 to the present was conducted. A variety of molecular genetic alterations have been identified in bladder cancer. Oncogenes (H-ras, erbB-2, EGFR, MDM2, C-MYC, CCND1), tumor suppressor genes (p53, Rb, p21, p27/KIP1, p16, PTEN, STK15, FHIT, FEZ1/LZTS1, bc10), telomerase, and methylation have all been studied in bladder cancer. Several have proven to be potentially useful clinical targets in the prognosis and therapy of bladder cancer such as staining for p53 and gene therapy strategies such as p53 and fez1. Clinical trials targeting HER2/neu and the EGFR pathways are underway. The UroVysion bladder cancer assay relies on FISH to detect genetic alterations in this disease. Continuing identification of the molecular genetic alterations in bladder cancer will enhance future diagnostic and therapeutic approaches to bladder cancer. Capitalizing on these alterations will allow early detection, providing important prognostic information and unique targets for gene therapy and other therapeutic approaches.

Loss of Fhit expression is associated with poorer survival in gastric cancer but is not an independent prognostic marker

Several studies have reported conflicting results regarding correlations of the loss of Fhit expression with clinicopathological parameters in gastric cancer. We investigated the immunohistochemical expression of Fhit in 362 cases of sporadic advanced gastric adenocarcinoma. The series included 64 cases with microsatellite instability associated with defective mismatch repair genes. Fhit expression resulted absent in 72% of the tumors analyzed. Absence of Fhit expression was more frequent in cases with diffuse and mixed histotype compared to the intestinal histotype (P=0.009). Absence of Fhit expression also correlated with tumor stage (P<0.001), lymph node involvement (P<0.001), presence of distant metastasis (P=0.033), and increasing histological grade (P=0.005). Retained Fhit expression also correlated with microsatellite instability as 61% of instable tumors had lost Fhit expression compared to 74% of microsatellite stable cancers (P=0.050). While loss of Fhit correlates with poorer survival in univariate analysis, it is not an independent prognostic factor in multivariate analysis and is thus not of clinical utility.

Inactivation of the FHIT gene favors bladder cancer development

The fragile histidine triad (FHIT) gene located on chromosome 3p14.2 is frequently deleted in human tumors. We have previously reported deletions at the FHIT locus in 50% of bladder carcinoma derived cell lines and reduced expression in 61% of primary transitional carcinomas of the urinary bladder. To additionally investigate the role of FHIT alterations in the development of bladder cancer, we used heterozygous and nullizygous Fhit-deficient mice in a chemically induced carcinogenesis model. Results showed that 8 of 28 (28%) and 6 of 13 (46%) of the Fhit -/- and +/-, respectively, versus 2 of 25 (8%) Fhit +/+ mice developed invasive carcinoma after treatment with N-butyl-N-(4-hydroxybutyl) nitrosamine. To explore the possibility of a FHIT-based gene therapy for bladder cancer, we studied the effects of restored Fhit protein expression on cell proliferation, cell kinetics, and tumorigenicity in BALB/c nude mice, with human SW780 Fhit-null transitional carcinoma derived cells. In vitro transduction of SW780 Fhit-negative cells with adenoviral-FHIT inhibited cell growth, increased apoptotic cell population, and suppressed s.c. tumor growth in nude mice. These findings suggest the important role of Fhit in bladder cancer development and support the effort to additionally investigate a FHIT-based gene therapy.