Ou WB, Hubert C, Corson JM, Bueno R, Flynn DL, Sugarbaker DJ, Fletcher JA.

Department of Pathology, Brigham and Women’s Hospital, Boston, MA, USA.

Abstract

The receptor tyrosine kinases (RTKs) epidermal growth factor receptor (EGFR) and MET are activated in subsets of mesothelioma, suggesting that these kinases might represent novel therapeutic targets in this notoriously chemotherapy-resistant cancer. However, clinical trials have shown little activity for EGFR inhibitors in mesothelioma. Despite the evidence for RTK activation in mesothelioma pathogenesis, it is unclear whether transforming activity is dependent on an individual kinase oncoprotein or the coordinated activity of multiple kinases. Using phospho-RTK and immunoblot assays, we herein demonstrate activation of multiple RTKs (EGFR, MET, AXL, and ERBB3) in individual mesothelioma cell lines but not in normal mesothelioma cells. Inhibition of mesothelioma multi-RTK signaling was accomplished using combinations of RTK direct inhibitors or by inhibition of the RTK chaperone, heat shock protein 90 (HSP90). Multi-RTK inhibition by the HSP90 inhibitor 17-allyloamino-17-demethoxygeldanamycin (17-AAG) had a substantially greater effect on mesothelioma proliferation and survival compared with inhibition of individual activated RTKs. HSP90 inhibition also suppressed phosphorylation of downstream signaling intermediates (AKT, mitogen-activated protein kinase, and S6); upregulated the p53, p21, and p27 cell cycle checkpoints; induced G(2) phase arrest; induced caspase 3/7 activity; and led to an increase in the sub-G(1) apoptotic population. These compelling proapoptotic and antiproliferative responses indicate that HSP90 inhibition warrants clinical evaluation as a novel therapeutic strategy in mesothelioma.

Li T, Li H, Wang Y, Harvard C, Tan JL, Au A, Xu Z, Jablons DM, You L.

Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California, San Francisco, CA 94143, USA.

Abstract

The chemokine CXCL12 and its receptors, CXCR4 and CXCR7, are involved in tumour progression, metastasis, and survival. We investigated the expression of CXCR4, CXCL12, and CXCR7 in malignant pleural mesothelioma to determine if they are possible biomarkers and potential therapeutic targets. Forty-one mesothelioma tumour tissues, ten normal human pleural tissues, and two mesothelioma cell lines were stained with anti-CXCR4, anti-CXCL12, anti-CXCR7, and anti-p-Akt antibodies. RT-PCR was performed to determine the expression of CXCR4, CXCL12, and CXCR7 in six human mesothelioma cell lines (H28, 211H, H2052, ms-1, H290, and H513) and one human normal mesothelial cell line, LP9. These seven cell lines were also stained with anti-CXCR7. We found that CXCR4 and CXCL12 were expressed in 97.6% and 78.0% mesothelioma tissue samples, concurrently with strong expression of p-Akt (R2 = 0.739 and 0.620, respectively). In addition, CXCR7 expression was weaker than CXCR4 expression in mesothelioma tissues. Furthermore, RT-PCR showed that CXCR4 and CXCL12 were overexpressed in 5/6 mesothelioma cell lines (211H, H2052, ms-1, H290, and H513), whereas CXCR7 was overexpressed in only 2/6 (H513 and H2052). Moreover, we found that the CXCR4 antagonist AMD3100 inhibited the growth of all five mesothelioma cell lines that overexpress CXCR4 and CXCL12. Our results suggest that the Akt–mTOR pathway is involved during the interruption of the CXCL12/CXCR4 axis in these five mesothelioma cell lines. In conclusion, CXCR4 and CXCL12 are highly expressed in most mesothelioma cell lines and tumour tissues, suggesting that CXCR4 and CXCL12 may be used as biomarkers for patients with mesothelioma. The CXCL12–CXCR4 interaction may be a potential therapeutic target for mesothelioma.

Keywords: mesothelioma; CXCL12; CXCR4; CXCR7; Akt

KaoSubramanian J, Corrales L, Soulieres D, Morgensztern D, Govindan R.

*Division of Oncology, Department of Medicine, Washington University School of Medicine; †Department of Medicine, Alvin J Siteman Cancer Center at Washington University School of Medicine, St Louis, Missouri; and ‡Department of Medicine, Centre Hospitalier de l’Université de Montréal, Montreal, Canada.

Abstract

Globally, lung cancer remains the most common cause of cancer-related death. In recent years, it has become clear that development of rational molecular targeted therapies is critical to improve the outcomes of patients with lung cancer. A better understanding of the tumor biology is crucial to achieve this goal. Several new findings in the field of tumor biology were presented at the 46th Annual Meeting of the American Society of Clinical Oncology. Novel genetic mutations were identified in pleural mesothelioma using array-based technologies. Several studies on the development and testing of new molecular diagnostic tests to detect epidermal growth factor receptor tyrosine kinase mutations and EML4-ALK (Echinoderm Microtubule-associated Protein like 4 Anaplastic Lymphoma Receptor Tyrosine Kinase) fusion gene were presented as well.

Yano S, Li Q, Wang W, Yamada T, Takeuchi S, Nakataki E, Ogino H, Goto H, Nishioka Y, Sone S.

Division of Medical Oncology, Cancer Research Institute, Kanazawa University. Kanazawa, Ishikawa 920-0934.

Abstract

Malignant pleural mesothelioma (MPM), arises from the mesothelial cells, is difficult to be diagnosed at an early stage, and is refractory to conventional chemotherapy and radiotherapy. Therefore, the establishment of novel effective therapies is necessary to improve the prognosis for many patients with this disease. Recent studies have demonstrated that angiogenesis plays a significant role in MPM progression, suggesting the importance of tumor vessels as therapeutic targets. To explore molecular pathogenesis and evaluate the efficacy of vascular targeting therapy in MPM, we developed orthotopic implantation SCID mouse models of MPM. We found that selective VEGF inhibitors were effective only in the treatment of high-VEGF-producing MPM models. On the other hand, multiple kinase inhibitor E7080, with inhibitory activity against various angiogenic cytokine receptors, suppressed the progression and prolonged survival of both high-VEGF-producing and low-VEGF-producing MPM models. Further understanding of the functional characteristics of tumor angiogenesis may be essential to improve targeting therapies in MPM. In this review, we introduce current status of clinical strategies and novel therapeutic approaches against angiogenesis in MPM.

Ramalingam SS, Belani CP, Ruel C, Frankel P, Gitlitz B, Koczywas M, Espinoza-Delgado I, Gandara D.

Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, Georgia, USA. suresh.ramalingam@emory.edu

Abstract

Background: Belinostat (PXD 101) is a novel inhibitor of class I and II histone deacetylases. This class of compounds has demonstrated anticancer activity in malignant mesothelioma. We conducted a phase II study of belinostat in patients with relapsed malignant pleural mesothelioma.

Methods: Patients with advanced mesothelioma, progression with one prior chemotherapy regimen and Eastern Cooperative Oncology Group performance status 0-2 were eligible. Belinostat was administered at 1000 mg/m intravenously over 30 minutes on days 1-5 of every 3 week cycle. The primary end point was response rate. The Simon two-stage design was used. Disease assessments were performed every two cycles.

Results: Thirteen patients were enrolled. Baseline characteristics were: median age of 73 years; Eastern Cooperative Oncology Group performance status 0 (n = 4), 1 (8) and 2 (1). A median of two cycles of therapy were administered. Disease stabilization was seen in two patients. No objective responses were noted and the study did not meet criteria to proceed to the second stage of accrual. Median survival was 5 months with a median progression-free survival of 1 month. Salient toxicities included nausea, emesis, fatigue, and constipation. One patient died as a consequence of cardiac arrhythmia which was deemed ‘possibly’ related to therapy.

Conclusions: Belinostat is not active as monotherapy against recurrent malignant pleural mesothelioma. Evaluation of combination strategies or alternate dosing schedules may be necessary for further development of this novel agent in mesothelioma.

Kim S, Buchlis G, Fridlender ZG, Sun J, Kapoor V, Cheng G, Haas A, Cheung HK, Zhang X, Corbley M, Kaiser LR, Ling L, Albelda SM.

Thoracic Oncology Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA.

Abstract

Locally produced transforming growth factor-beta (TGF-beta) promotes tumor-induced immunosuppression and contributes to resistance to immunotherapy. This article explores the potential for increased efficacy when combining immunotherapies with TGF-beta suppression using the TGF-beta type I receptor kinase inhibitor SM16. Adenovirus expressing IFN-beta (Ad.IFN-beta) was injected intratumorally once in established s.c. AB12 (mesothelioma) and LKR (lung cancer) tumors or intratracheally in a Kras orthotopic lung tumor model. Mice bearing TC1 (lung cancer) tumors were vaccinated with two injections of adenovirus expressing human papillomavirus-E7 (HPV-E7; Ad.E7). SM16 was administered orally in formulated chow. Tumor growth was assessed and cytokine expression and cell populations were measured in tumors and spleens by real-time PCR and flow cytometry. SM16 potentiated the efficacy of both immunotherapies in each of the models and caused changes in the tumor microenvironment. The combination of SM16 and Ad.IFN-beta increased the number of intratumoral leukocytes (including macrophages, natural killer cells, and CD8(+) cells) and increased the percentage of T cells expressing the activation marker CD25. SM16 also augmented the antitumor effects of Ad.E7 in the TC1 flank tumor model. The combination did not increase HPV-E7 tetramer-positive CD8(+) T cells in the spleens but did induce a marked increase in the tumors. Tumors from SM16-treated mice showed increased mRNA and protein for immunostimulatory cytokines and chemokines, as well as endothelial adhesion molecules, suggesting a mechanism for the increased intratumoral leukocyte trafficking. Blockade of the TGF-beta signaling pathway augments the antitumor effects of Ad.IFN-beta immune-activating or Ad.E7 vaccination therapy. The addition of TGF-beta blocking agents in clinical trials of immunotherapies may increase efficacy.

Kaneko O, Gong L, Zhang J, Hansen JK, Hassan R, Lee B, Ho M.

Laboratory of Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.

Abstract

Ovarian cancer and malignant mesothelioma frequently express both mesothelin and CA125 (also known as MUC16) at high levels on the cell surface. The interaction between mesothelin and CA125 may facilitate the implantation and peritoneal spread of tumors by cell adhesion, whereas the detailed nature of this interaction is still unknown. Here, we used truncated mutagenesis and alanine replacement techniques to identify a binding site on mesothelin for CA125. We examined the molecular interaction by Western blot overlay assays and further quantitatively analyzed by enzyme-linked immunosorbent assay. We also evaluated the binding on cancer cells by flow cytometry. We identified the region (296-359) consisting of 64 amino acids at the N-terminal of cell surface mesothelin as the minimum fragment for complete binding activity to CA125. We found that substitution of tyrosine 318 with an alanine abolished CA125 binding. Replacement of tryptophan 321 and glutamic acid 324 with alanine could partially decrease binding to CA125, whereas mutation of histidine 354 had no effect. These results indicate that a conformation-sensitive structure of the region (296-359) is required and sufficient for the binding of mesothelin to CA125. In addition, we have shown that a single chain monoclonal antibody (SS1) recognizes this CA125-binding domain and blocks the mesothelin-CA125 interaction on cancer cells. The identified CA125-binding domain significantly inhibits cancer cell adhesion and merits evaluation as a new therapeutic agent for preventing or treating peritoneal malignant tumors.

Akay OM, Ustuner Z, Canturk Z, Mutlu FS, Gulbas Z.

Department of Hematology, Eskisehir Osmangazi University Medical School, 26480, Eskisehir, Turkey, olga.akay@hotmail.com.

Abstract

The goal of this study was laboratory testing for hypercoagulability in patients with solid tumors using rotation thrombelastogram (ROTEM®) and correlate ROTEM® parameters with routine coagulation tests. A total of 78 untreated patients with cancer were included: 28 gastrointestinal system tumors (group 1), 27 respiratory system tumors (group 2), and 23 miscellaneus group of ovarian, renal, nasopharyngeal, mesothelioma, and unknown origin (group 3). Platelet count was significantly increased in group 2 in respect to group 3 (P < 0.05) and fibrinogen level was significantly increased in group 2 in respect to group 1 (P < 0.05). There was no statistically significant difference between subgroups in respect to TEG parameters. Tumor-node-metastasis (TNM) stages of patients was not also associated with either of TEG parameters. Correlation analysis revealed significant correlation between laboratory parameters and ROTEM® parameters. Fibrinogen showed the strongest correlation with MCF (r > 0.7) and CFT in all assays (INTEM, EXTEM, FIBTEM, APTEM). There were also statistically significant correlations between platelet number and other ROTEM® parameters (INTEM-CFT, -MCF, EXTEM-CFT, -MCF, FIBTEM-MCF, APTEM-CFT, -MCF). In conclusions, our data demonstrates thromboelastographic signs of hypercoagulability in patients with solid tumors. ROTEM® is able to identify the contribution of fibrinogen and platelets to clot strength in this patient population.

Keywords: Thrombelastography, Thrombosis, Cancer

Turcotte RF, Raines RT.

Medical Scientist Training Program and Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI 53706, USA.

Abstract

One of the tightest known protein–protein interactions in biology is that between members of the ribonuclease A superfamily and the ribonuclease inhibitor protein (RI). Some members of this superfamily are able to kill cancer cells, and the ability to evade RI is a major determinant of whether a ribonuclease will be cytotoxic. The archetypal cytotoxic ribonuclease, onconase (ONC), is in late-stage clinical trials for the treatment of malignant mesothelioma. We present here the first measurement of the inhibition of the ribonucleolytic activity of ONC by RI. This inhibition occurs with K_i = 0.15 μM in a solution of low salt concentration.

Keywords: Cancer; Cytotoxin; Enzyme inhibition; Onconase; Ribonuclease; Salt concentration

Abbreviations: RNase A, bovine pancreatic ribonuclease; RI, ribonuclease inhibitor protein; PBS, phosphate-buffered saline; RNase 1, human pancreatic ribonuclease; ONC, onconase

Stoppoloni D, Cardillo I, Verdina A, Vincenzi B, Menegozzo S, Santini M, Sacchi A, Baldi A, Galati R.

Laboratory D, Department for the Development of Therapeutic Programs, Centro Ricerca Sperimentale, Regina Elena Cancer Institute, Rome, Italy.

Abstract

Background:
The human embryonic lethal abnormal vision (ELAV)-like protein HuR is a messenger RNA (mRNA)-binding protein that controls the stability of certain transcripts, including cyclooxygenase2 (COX-2).

Methods:
To investigate a possible contribution of dysregulation of mRNA stability to the progression of cancer and to COX-2 over expression in mesothelioma, the authors studied expression of COX-2 and HuR in 5 mesothelioma cell lines (MSTO, NCI, Ist-Mes1, Ist-Mes2, and MPP89) and in a group of 29 human mesothelioma specimens that were characterized previously for COX-2 expression.

Results:
All 5 cell lines expressed HuR, whereas COX-2 was not detectable in MSTO or NCI cells. Treatment with cytokines induced a shift in systolic HuR protein levels in MPP89 and Ist-Mes2 cells that was accompanied by an increase in the expression of COX-2 mRNA and protein. In Ist-Mes1 cells, cytokine stimulation did not cause the passage of HuR from nucleus to cytoplasm, and the synthesis of COX-2 did not increase. In tumor tissues, immunohistochemistry revealed a positive, statistically significant correlation between high COX-2 expression and cytoplasmic localization of HuR (P = .016). Moreover, on univariate analysis, overall survival was found to be influenced strongly by cytoplasmic HuR localization (P = .004).

Conclusions:
The current results suggested that HuR plays a role in tumor progression in mesothelioma and that COX-2 may be a target of its activity in neoplastic cells. Together, these observations indicate that strategies aiming toward the modulation of HuR may have a potential clinical benefit in mesothelioma.

Keywords: human embryonic lethal abnormal vision-like protein, cyclooxygenase-2, mesothelioma, prognosis, immunohistochemistry