Malamati Vreka

Mast cells mediate malignant pleural effusion formation

Mast cells (MCs) have been identified in various tumors; however, the role of these cells in tumorigenesis remains controversial. Here, we quantified MCs in human and murine malignant pleural effusions (MPEs) and evaluated the fate and function of these cells in MPE development. Evaluation of murine MPE-competent lung and colon adenocarcinomas revealed that these tumors actively attract and subsequently degranulate MCs in the pleural space by elaborating CCL2 and osteopontin. MCs were required for effusion development, as MPEs did not form in mice lacking MCs, and pleural infusion of MCs with MPE-incompetent cells promoted MPE formation. Once homed to the pleural space, MCs released tryptase AB1 and IL-1β, which in turn induced pleural vasculature leakiness and triggered NF-κB activation in pleural tumor cells, thereby fostering pleural fluid accumulation and tumor growth. Evaluation of human effusions revealed that MCs are elevated in MPEs compared with benign effusions. Moreover, MC abundance correlated with MPE formation in a human cancer cell-induced effusion model. Treatment of mice with the c-KIT inhibitor imatinib mesylate limited effusion precipitation by mouse and human adenocarcinoma cells. Together, the results of this study indicate that MCs are required for MPE formation and suggest that MC-dependent effusion formation is therapeutically addressable.

Comprehensive Evaluation of Nuclear Factor-κΒ Expression Patterns in Non-Small Cell Lung Cancer.

Nuclear factor (NF)-κB signalling is required for lung adenocarcinoma development in mice, and both of its subunits RelA and RelB were independently reported to be highly expressed in human non-small cell lung cancer (NSCLC). To comprehensively examine NF-κB expression in NSCLC, we analyzed serial sections of primary tumor samples from 77 well-documented patients (36 adenocarcinomas, 40 squamous cell carcinomas and 3 large cell carcinomas) for immunoreactivity of RelA, RelB, P50, and P52/P100. Tumor and intratumoral stroma areas were discriminated based on proliferating cell nuclear antigen immunoreactivity and inflammatory infiltration was assessed in intratumoral stroma areas. NF-κB immunoreactivity was quantified by intensity, extent, and nuclear localization and was cross-examined with tumor cell proliferation, inflammatory infiltration, and clinical-pathologic data. We found that the expression of the different NF-κB subunits was not concordant, warranting our integral approach. Overall, RelA, RelB, and P50 were expressed at higher levels compared with P52/P100. However, RelA and P50 were predominantly expressed in intratumoral stroma, but RelB in tumor cells. Importantly, tumor area RelA expression was correlated with the intensity of inflammatory infiltration, whereas RelB expression was identified in proliferating tumor cells. Using multiple logistic regression, we identified that tumor RelB expression was an independent predictor of lymph node metastasis, and tumor P50 was an independent predictor of TNM6 stage IIB or higher, whereas tumor RelA was an independent predictor of inflammatory infiltration. We conclude that pathologic studies of NF-κB expression in cancer should include multiple pathway components. Utilizing such an approach, we identified intriguing associations between distinct NF-κB subunits and clinical and pathologic features of NSCLC.

Mutant KRAS promotes malignant pleural effusion formation

Malignant pleural effusion (MPE) is the lethal consequence of various human cancers metastatic to the pleural cavity. However, the mechanisms responsible for the development of MPE are still obscure. Here we show that mutant KRAS is important for MPE induction in mice. Pleural disseminated, mutant KRAS bearing tumour cells upregulate and systemically release chemokine ligand 2 (CCL2) into the bloodstream to mobilize myeloid cells from the host bone marrow to the pleural space via the spleen. These cells promote MPE formation, as indicated by splenectomy and splenocyte restoration experiments. In addition, KRAS mutations are frequently detected in human MPE and cell lines isolated thereof, but are often lost during automated analyses, as indicated by manual versus automated examination of Sanger sequencing traces. Finally, the novel KRAS inhibitor deltarasin and a monoclonal antibody directed against CCL2 are equally effective against an experimental mouse model of MPE, a result that holds promise for future efficient therapies against the human condition.

ΙκΒ kinase α is required for development and progression of KRAS-mutant lung adenocarcinoma.

Although oncogenic activation of NFκB has been identified in various tumors, the NFκB-activating kinases (inhibitor of NFκB kinases, IKK) responsible for this are elusive. In this study, we determined the role of IKKα and IKKβ in KRAS-mutant lung adenocarcinomas induced by the carcinogen urethane and by respiratory epithelial expression of oncogenic KRASG12D Using NFκB reporter mice and conditional deletions of IKKα and IKKβ, we identified two distinct early and late activation phases of NFκB during chemical and genetic lung adenocarcinoma development, which were characterized by nuclear translocation of RelB, IκBβ, and IKKα in tumor-initiated cells. IKKα was a cardinal tumor promoter in chemical and genetic KRAS-mutant lung adenocarcinoma, and respiratory epithelial IKKα-deficient mice were markedly protected from the disease. IKKα specifically cooperated with mutant KRAS for tumor induction in a cell-autonomous fashion, providing mutant cells with a survival advantage in vitro and in vivo IKKα was highly expressed in human lung adenocarcinoma, and a heat shock protein 90 inhibitor that blocks IKK function delivered superior effects against KRAS-mutant lung adenocarcinoma compared with a specific IKKβ inhibitor. These results demonstrate an actionable requirement for IKKα in KRAS-mutant lung adenocarcinoma, marking the kinase as a therapeutic target against this disease.Significance: These findings report a novel requirement for IKKα in mutant KRAS lung tumor formation, with potential therapeutic applications. Cancer Res; 78(11); 2939-51. ©2018 AACR.

LSC - 2017 - KRAS & TP53 mutations cause malignant mesothelioma

Background: Malignant pleural mesothelioma (MPM) is a highly aggressive tumor linked to loss of tumor suppressorsBAP1, NF2, andTRP53and accompanied by malignant pleural effusion (MPE). Aim: To develop novel mouse models of MPM with MPE. Methods: Intercrosses of conditional mutantKRAS (LoxP-STOP-LoxP.KRASG12D; K) andTRP53-deleted (LoxP.Trp53.LoxP; P) mice received intrapleural adenovirus-Cre. Pleural tumors were molecularly phenotyped and cultured to isolate cell lines, which were inoculated into the pleurae of naive mice. Results: K mice developed lethal epithelioid MPM (median, 95%CI survival: 339, 285-379 days). KP mice succumbed to sarcomatoid MPM (median, 95%CI survival 40, 38-72 days) accompanied by MPE (mean±SD volume 349±269 µL). KP mice also developed peritoneal mesothelioma upon intraperitoneal adenovirus-Cre. Mouse MPMs expressed calretinin, podoplanin, and osteopontin, but not surfactant protein C. MPM cell lines were isolated from KP MPM, which transplanted MPM to naiveC57BL/6mice causing their death (median, 95%CI survival 26, 25-28 days) by MPE induction (mean±SD volume 387±180 µL). The models harbored secondary BAP1, NF2 and CDKN2 mutations. Treatment of KP mice with a KRAS inhibitor resulted in increased survival and halted MPM growth and MPE formation. Conclusions: We developed multiple models of primary and transplantable MPM that show thatKRASandTP53mutations can initiate the disease and cause secondaryBAP1andNF2loss. Funding ERC Grants #260524 and #679345.

New insights on pleural fluid formation: potential translational targets

Pleural effusion is a very common clinical problem associated with a multitude of different underlying conditions, including infection, heart failure, and cancer. Current treatments for pleural effusion often aim at symptom relief rather than at treating its underlying cause. Recent investigations have provided new insights into the mechanisms of fluid accumulation in the pleural space and hence hope for clinical translation of the novel therapy to stop fluid formation. Here, we discuss the major mechanistic findings of recent basic, translational, and clinical studies that have aimed at tackling the management and the pathobiology of the most common types of pleural effusions. In addition, we analyze the current and potential future uses of these novel data in the management of patients with pleural effusion.