Defining and targeting tumor-associated macrophages in malignant mesothelioma.

Defining the ontogeny of tumor-associated macrophages (TAM) is important to develop therapeutic targets for mesothelioma. We identified two distinct macrophage populations in mouse peritoneal and pleural cavities, the monocyte-derived, small peritoneal/pleural macrophages (SPM), and the tissue-resident large peritoneal/pleural macrophages (LPM). SPM rapidly increased in tumor microenvironment after tumor challenge and contributed to the vast majority of M2-like TAM. The selective depletion of M2-like TAM by conditional deletion of the Dicer1 gene in myeloid cells (D-/-) promoted tumor rejection. Sorted SPM M2-like TAM initiated tumorigenesis in vivo and in vitro, confirming their capacity to support tumor development. The transcriptomic and single-cell RNA sequencing analysis demonstrated that both SPM and LPM contributed to the tumor microenvironment by promoting the IL-2-STAT5 signaling pathway, inflammation, and epithelial-mesenchymal transition. However, while SPM preferentially activated the KRAS and TNF-α/NFkB signaling pathways, LPM activated the IFN-γ response. The importance of LPM in the immune response was confirmed by depleting LPM with intrapleural clodronate liposomes, which abrogated the antitumoral memory immunity. SPM gene signature could be identified in pleural effusion and tumor from patients with untreated mesothelioma. Five genes, TREM2, STAB1, LAIR1, GPNMB, and MARCO, could potentially be specific therapeutic targets. Accordingly, Trem2 gene deletion led to reduced SPM M2-like TAM with compensatory increase in LPM and slower tumor growth. Overall, these experiments demonstrate that SPM M2-like TAM play a key role in mesothelioma development, while LPM more specifically contribute to the immune response. Therefore, selective targeting of monocyte-derived TAM may enhance antitumor immunity through compensatory expansion of tissue-resident TAM.

JSI-124 inhibits cell proliferation and tumor growth by inducing autophagy and apoptosis in murine malignant mesothelioma.

Malignant pleural mesothelioma (MPM), mainly caused by asbestos exposure, has a poor prognosis and lacks effective treatment compared with other cancer types. The intracellular transcription factor signal transducer and activator of transcription 3 (STAT3) is overexpressed and hyperactivated in most human cancers. In this study, the role of STAT3 in murine MPM was examined. Inhibition of the Janus kinase 2 (JAK2)/STAT3 pathway with the selective inhibitor JSI-124 has an antitumor effect in murine MPM. Specifically, we demonstrated that JSI-124 inhibits murine MPM cell growth and induces apoptotic and autophagic cell death. Exposure of RN5 and AB12 cells to JSI-124 resulted in apoptosis via the Bcl-2 family of proteins. JSI-124 triggered autophagosome formation, accumulation, and conversion of LC3I to LC3II. Autophagy inhibitors, Chloroquine (CQ) and Bafilomycin A1 (Baf-A1), inhibited autophagy and sensitized RN5 and AB12 cells to JSI-124-induced apoptosis. Our data indicate that JSI-124 is a promising therapeutic agent for MPM treatment.

Prognostic Value of EMT Gene Signature in Malignant Mesothelioma.

Malignant mesothelioma (MESO) consists of epithelioid, biphasic, and sarcomatoid subtypes with different epithelial-mesenchymal transition (EMT) phenotypes. We previously identified a panel of four MESO EMT genes correlating with an immunosuppressive tumor microenvironment and poor survival. In this study, we investigated the correlation between these MESO EMT genes, the immune profile, and the genomic and epigenomic alterations to identify potential therapeutic targets to prevent or reverse the EMT process. Using multiomic analysis, we observed that the MESO EMT genes were positively correlated with hypermethylation of epigenetic genes and loss of CDKN2A/B expression. MESO EMT genes such as COL5A2, ITGAV, SERPINH1, CALD1, SPARC, and ACTA2 were associated with upregulation of TGF-ß signaling, hedgehog signaling, and IL-2-STAT5 signaling and downregulation of the IFN-α and IFN-γ response. Immune checkpoints such as CTLA4, CD274 (PD-L1), PDCD1LG2 (PD-L2), PDCD1 (PD-1), and TIGIT were upregulated, while LAG3, LGALS9, and VTCN1 were downregulated with the expression of MESO EMT genes. CD160, KIR2DL1, and KIR2DL3 were also broadly downregulated with the expression of MESO EMT genes. In conclusion, we observed that the expression of a panel of MESO EMT genes was associated with hypermethylation of epigenetic genes and loss of expression of CDKN2A and CDKN2B. Expression of MESO EMT genes was associated with downregulation of the type I and type II IFN response, loss of cytotoxicity and NK cell activity, and upregulation of specific immune checkpoints, as well as upregulation of the TGF-ß1/TGFBR1 pathway.

Foxp3+ Regulatory T Cell Depletion after Nonablative Oligofractionated Irradiation Boosts the Abscopal Effects in Murine Malignant Mesothelioma.

Increasing evidence indicates that local hypofractionated radiotherapy (LRT) can elicit both immunogenic and immunosuppressive local and systemic immune responses. We thus hypothesized that blockade of LRT-induced immunosuppressive responses could augment the antitumor effects and induce an abscopal response. In this study, we found that the upregulation of Foxp3+ regulatory T cells (Tregs) in the mesothelioma tumor microenvironment after nonablative oligofractionated irradiation significantly limited the success of irradiation. Using DEREG mice, which allow conditional and efficient depletion of Foxp3+ Tregs by diphtheria toxin injection, we observed that transient Foxp3+ Treg depletion immediately after nonablative oligofractionated irradiation provided synergistic local control and biased the T cell repertoire toward central and effector memory T cells, resulting in long-term cure. Furthermore, this combination therapy showed significant abscopal effect on the nonirradiated tumors in a concomitant model of mesothelioma through systemic activation of cytotoxic T cells and enhanced production of IFN-γ and granzyme B. Although local control was preserved with one fraction of nonablative irradiation, three fractions were required to generate the abscopal effect. PD-1 and CTLA-4 were upregulated on tumor-infiltrating CD4+ and CD8+ T cells in irradiated and nonirradiated tumors, suggesting that immune checkpoint inhibitors could be beneficial after LRT and Foxp3+ Treg depletion. Our findings are applicable to the strategy of immuno-radiotherapy for generating optimal antitumor immune responses in the clinical setting. Targeting Tregs immediately after a short course of irradiation could have a major impact on the local response to irradiation and its abscopal effect.

Putative cancer stem cells may be the key target to inhibit cancer cell repopulation between the intervals of chemoradiation in murine mesothelioma.

BACKGROUND: Cancer cell repopulation during chemotherapy or radiotherapy is a major factor limiting the efficacy of treatment. Cancer stem cells (CSC) may play critical roles during this process. We aim to demonstrate the role of mesothelioma stem cells (MSC) in treatment failure and eventually to design specific target therapies against MSC to improve the efficacy of treatment in malignant mesothelioma. METHODS: Murine mesothelioma AB12 and RN5 cells were used to compare tumorigenicity in mice. The expression of CSC-associated genes was evaluated by quantitative real-time PCR in both cell lines treated with chemo-radiation. Stemness properties of MSC-enriched RN5-EOS-Puro2 cells were characterized with flow cytometry and immunostaining. A MSC-specific gene profile was screened by microarray assay and confirmed thereafter. Gene Ontology analysis of the selected genes was performed by GOMiner. RESULTS: Tumor growth delay of murine mesothelioma AB12 cells was achieved after each cycle of cisplatin treatment, however, tumors grew back rapidly due to cancer cell repopulation between courses of chemotherapy. Strikingly, a 10-times lower number of irradiated cells in both cell lines led to a similar tumor incidence and growth rate as with untreated cells. The expression of CSC-associated genes such as CD24, CD133, CD90 and uPAR was dramatically up-regulated, while others did not change significantly after chemoradiation. Highly enriched MSC after selection with puromycin displayed an increasing GFP-positive population and showed typical properties of stemness. Comparatively, the proportion of MSC significantly increased after RN5-EOS parental cells were treated with either chemotherapy, γ-ray radiation, or a combination of the two, while MSC showed more resistance to the above treatments. A group of identified genes are most likely MSC-specific, and major pathways related to regulation of cell growth or apoptosis are involved. Upregulation of the gene transcripts Tnfsf18, Serpinb9b, Ly6a, and Nppb were confirmed. CONCLUSION: Putative MSC possess the property of stemness showing more resistance to chemoradiation, suggesting that MSC may play critical roles in cancer cell repopulation. Further identification of selected genes may be used to design novel target therapies against MSC, so as to eliminate cancer cell repopulation in mesothelioma.

Radiotherapy for the treatment of malignant pleural mesothelioma.

Malignant pleural mesothelioma is an aggressive disease that continues to be associated with poor outcomes. Although, traditionally this disease is considered to be resistant to radiotherapy, more recent evidence suggests that radiotherapy can produce positive outcomes. Over the past 15 years, the development of new, highly conformal radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), has enabled investigators to optimise the delivery of high-dose radiotherapy to the whole of the hemithorax. Prospective single-arm trials have shown that the median survival of patients who have completed high-dose hemithoracic radiotherapy after extrapleural pneumonectomy could reach 23·9-39·4 months independent of the chemotherapeutic response, suggesting that IMRT could potentially have an intrinsic benefit to this subset of patients. These observations have led to a change in practice, with the introduction of adjuvant pleural IMRT after pleurectomy-decortication and the development of induction-accelerated hemithoracic IMRT followed by extrapleural pneumonectomy. This Review focuses on recent observations on the role of radiotherapy in the treatment of malignant pleural mesothelioma, with particular emphasis on the results of clinical trials that evaluate the role of high-dose hemithoracic radiotherapy.

Prognostic value of several biomarkers for the patients with malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor of the pleura closely related to asbestos exposure. Rare as it is, the incidence of MPM is predicted to increase mainly as a result of a lengthy latency period from the initial asbestos exposure, making it a public health concern for the next decades. Moreover, the patients with MPM have an extremely poor prognosis due to its high resistance to conventional oncologic treatments and delayed diagnosis. Although the result of current therapeutic modalities based on patient features and clinical stages is very frustrating, great advances have been shown in the knowledge of molecular biology of MPM in recent years. This is accompanied by dozens of putative prognostic biomarkers that are actively involved in tumor biological activities. These prognostic candidates can offer us a new insight into the biological characteristics of MPM, contributing to development of individualized therapeutic strategies directed against oncogenesis and tumor progression. Thus, personalized approaches based on the molecular biology of the patient's tissue or body fluid will potentially improve the present disappointing outcome, bringing new hope for patients with MPM. This article reviews the principal and several novel biomarkers that can have an influence on prognosis, in the hope that they can provide us with a more profound understanding of the biology of this lethal disease.

[Mechanism of Polypeptide Extract from Scorpion Venom Combined Rapamycin in Enhancing Autophagy of H22 Hepatoma Cells: an Experimental Study].

OBJECTIVE: To observe enhanced effects of polypeptide extract from scorpion venom (PESV) combined Rapamycin on autophagy of H22 hepatoma cells in mice and to explore its possible mechanism. METHODS: The H22 hepatocarcinoma cell suspension was subcutaneously inoculated into 40 Kunming mice. Then tumor-bearing mice were randomly divided into four groups, i.e., the control group,the high dose PESV group, the low dose PESV group, and the combination group (high dose PESV + Rapamycin), 10 in each group. Mice in high and dose PESV groups were administered with 20 mg/kg and 10 mg/kg PESV respectively by gastrogavage. Mice in the combination group were administered with 2 mg/kg rapamycin and 20 mg/kg PESV by gastrogavage. The intervention lasted for 14 successive days. The tumor volume was measured once every other day, the tumor growth curve was drawn, and then the tumor inhibitory rate calculated. Pathological changes of the tumor tissue were observed by HE staining. Protein expression levels of mammal target of rapamycin (mTOR), UNC-51-like kinase-1 (ULK1), microtubule-associated protein1 light chain3 (MAPILC3A), and Beclin1 were detected by immunohistochemical assay. RESULTS: The growth of H22 hepatoma transplantation tumor was inhibited in high and low dose PESV groups and the combination group (P < 0.05). And there was statistical difference in tumor weight and tumor volume between the combination group and high and low dose PESV groups (P < 0.05). There was no statistical difference in tumor weight or tumor volume between the high dose PESV group and the low dose PESV group (P > 0.05). lmmunohistochemical assay showed that the protein expression of mTOR was higher, but protein expressions of ULK1, MAP1LC3A, Beclin1 were lower in the control group than in the rest 3 groups (P < 0.05, P < 0.01). Compared with the high dose PESV group, protein expressions of ULK1, MAP1LC3A, and Beclin1 were obviously lower (P < 0.05). CONCLUSION: PESV combined Rapamycin might inhibit the development of H22 hepatoma transplantation tumor in mice possibly through inhibiting the activity of mTOR, enhancing expressions of ULK1, MAP1LC3A, and Beclin1.

Activation of CD1d-restricted natural killer T cells can inhibit cancer cell proliferation during chemotherapy by promoting the immune responses in murine mesothelioma.

We studied the impact of natural killer T (NKT) cell activation by alpha-galactocysylceramide (α-GalCer, α-GC) on cancer cell repopulation during chemotherapy in murine mesothelioma. The number of NKT cells was found to be increased during the development of murine mesothelioma. NKT cells specifically recognize α-GC through CD1d resulting in their activation and expansion. Tumor-bearing mice were treated with chemotherapy once weekly, and α-GC was followed after each cycle of chemotherapy. Anti-tumor effect was evaluated on wild-type (WT) and CD1d knockout (CD1dKO) mice. Cancer cell proliferation and apoptosis were evaluated by Ki67 and TUNEL immunohistochemistry. CD4(+) and CD8(+) T cell proportion and activation in tumor, spleen, draining lymph node and peripheral blood were determined by flow cytometry, and gene expression of activated T cell-related cytokines was quantified by reverse transcription PCR. NKT cells were identified by CD1d-α-GC-tetramer staining. In WT mice, tumor growth delay was achieved by cisplatin (Cis), and this effect was improved in combination with α-GC, but α-GC alone had little effect. Cancer cell proliferation during chemotherapy was significantly inhibited by α-GC, while cancer cell death was significantly upregulated. α-GC following chemotherapy resulted in NKT cell expansion and an increase of interferon-γ production in the draining lymph node, blood and spleen. Gene expression of immune-associated cytokines was upregulated. Strikingly, the percentage of inducible T cell co-stimulator(+)CD4 T cells, Th17/Tc17 cells increased in splenocytes. In CD1d KO mice, however, Cis alone was less effective and Cis + α-GC provided no additional benefit over Cis alone. α-GC alone had minimal effect in both mice. NKT activation between cycles of chemotherapy could improve the outcome of mesothelioma treatment.

[Study on the mechanism of polypeptide extract from scorpion venom on inhibition of angiogenesis of H 22 hepatoma].

OBJECTIVE: To explore the mechanism of polypeptide extract from scorpion venom (PESV) on inhibiting angiogenesis. METHODS: The H22 hepatoma tumor model was established by subcutaneously implanting H22 hepatoma cells into mice. The tumor-bearing mice were randomly divided into 4 groups, i.e., the control group, the high dose PESV group, the low dose PESV group, and the 5-fluorouracil (5-Fu) group, 10 mice in each group. The intervention was lasted for 14 days. The growth curve of the tumor volume was drawn and the inhibition rate calculated. Pathological changes of the tumors were observed by HE staining. The microvessel density (MVD) was detected using SP method. The protein expression levels of phosphatidylinositol 3-kinase (P13K), phosphoprotein kinase B (P-Akt), hypoxia-inducible factor-1 alpha (HIF-1 )alpha, and vascular endothelial growth factor-A (VEGF-A) were detected by immunohistochemical assay and Western blot. RESULTS: The tumor inhibitory rate was 64.8%, 43.7%, and 32.4% in the 5-Fu group, the high dose PESV group, and the low dose PESV group. Compared with the control group, the protein expression of PI3K, P-Akt, HIF-1alpha, and VEGF-A were obviously inhibited by PESV and 5-Fu (P <0. 05,P <0. 01). The MVD also decreased in the high and low dose PESV groups (P < 0.05). CONCLUSIONS: PESV could inhibit the angiogenesis of H22 hepatoma. The mechanisms might be associated with suppressing the expression of PI3K, P-Akt, HIF-1 alpha, and VEGF-A.

Liquid crystalline phase behavior and sol-gel transition in aqueous halloysite nanotube dispersions.

The liquid crystalline phase behavior and sol-gel transition in halloysite nanotubes (HNTs) aqueous dispersions have been investigated by applying polarized optical microscopy (POM), macroscopic observation, rheometer, small-angle X-ray scattering, scanning electron microscopy, and transmission electron microscopy. The liquid crystalline phase starts to form at the HNT concentration of 1 wt %, and a full liquid crystalline phase forms at the HNT concentration of 25 wt % as observed by POM and macroscopic observation. Rheological measurements indicate a typical shear flow behavior for the HNT aqueous dispersions with concentrations above 20 wt % and further confirm that the sol-gel transition occurs at the HNT concentration of 37 wt %. Furthermore, the HNT aqueous dispersions exhibit pH-induced gelation with more intense birefringence when hydrochloric acid (HCl) is added. The above findings shed light on the phase behaviors of diversely topological HNTs and lay the foundation for fabrication of the long-range ordered nano-objects.

[Research on the effect and mechanism of polypeptide extract from scorpion venom combined with 5-fluorouracil on vasculogenic mimicry of H22 hepatoma].

OBJECTIVE: To observe the inhibition effects of polypeptide extract from scorpion venom (PESV) combined 5-fluorouracil (5-Fu) on vasculogenic mimicry (VM) of H2 hepatoma carcinoma cells in mice and its possible mechanisms. METHODS: The H22 carcinoma cell suspension was subcutaneously inoculated into 60 Kunming mice. Then tumor-bearing mice were randomly divided into three groups, i.e., the control group, the 5-Fu group, and the combination group (PESV +5-Fu), 20 in each group. The tumor volume was measured once every other day after 14 successive days of intervention. Then the tumor volume growth curve was drawn, and the tumor inhibitory rate was calculated. The morphological changes of the tumor tissue were observed by HE staining. The VM density of each tumor tissue were detected by immunohistochemical assay and periodic acid-schiff stain (PAS). The protein expression levels of hypoxia inducible factor-la (HIF-la) and matrix metalloproteinase-2 (MMP-2) were detected using immunohistochemical assay. The gray value was semi-quantitatively analyzed using LeicaQwinV3 Image Analysis Software. RESULTS: The growth of H22 hepatoma transplantation tumor was inhibited more obviously in the combination group and the 5-Fu group than in the control group (P <0.05). There was statistical difference in the tumor weight and the tumor volume between the combination group and the 5-Fu group (P <0.05). Immunohistochemical assay and PAS showed that the VM density was obviously lower in the combination group than in the control group and the 5-Fu group (P <0.01). Compared with the control group, the protein expressions of HIF-la and MMP-2 significantly decreased in the combination group (P <0.01). CONCLUSIONS: PESV combined 5-Fu could inhibit the generation of VM of H22 hepatoma transplantation tumor in mice. Its mechanisms might be associated with inhibiting the expressions of HIF-lalpha and MMP-2 in the microenvironment of tumors.

Omics Overview of the SPARC Gene in Mesothelioma.

The SPARC gene plays multiple roles in extracellular matrix synthesis and cell shaping, associated with tumor cell migration, invasion, and metastasis. The SPARC gene is also involved in the epithelial-mesenchymal transition (EMT) process, which is a critical phenomenon leading to a more aggressive cancer cell phenotype. SPARC gene overexpression has shown to be associated with poor survival in the mesothelioma (MESO) cohort from the TCGA database, indicating that this gene may be a powerful prognostic factor in MESO. Its overexpression is correlated with the immunosuppressive tumor microenvironment. Here, we summarize the omics advances of the SPARC gene, including the summary of SPARC gene expression associated with prognosis in pancancer and MESO, the immunosuppressive microenvironment, and cancer cell stemness. In addition, SPARC might be targeted by microRNAs. Notably, despite the controversial functions on angiogenesis, SPARC may directly or indirectly contribute to tumor angiogenesis in MESO. In conclusion, SPARC is involved in tumor invasion, metastasis, immunosuppression, cancer cell stemness, and tumor angiogenesis, eventually impacting patient survival. Strategies targeting this gene may provide novel therapeutic approaches to the treatment of MESO.

Unlocking the potential of RNA-based therapeutics in the lung: current status and future directions.

Awareness of RNA-based therapies has increased after the widespread adoption of mRNA vaccines against SARS-CoV-2 during the COVID-19 pandemic. These mRNA vaccines had a significant impact on reducing lung disease and mortality. They highlighted the potential for rapid development of RNA-based therapies and advances in nanoparticle delivery systems. Along with the rapid advancement in RNA biology, including the description of noncoding RNAs as major products of the genome, this success presents an opportunity to highlight the potential of RNA as a therapeutic modality. Here, we review the expanding compendium of RNA-based therapies, their mechanisms of action and examples of application in the lung. The airways provide a convenient conduit for drug delivery to the lungs with decreased systemic exposure. This review will also describe other delivery methods, including local delivery to the pleura and delivery vehicles that can target the lung after systemic administration, each providing access options that are advantageous for a specific application. We present clinical trials of RNA-based therapy in lung disease and potential areas for future directions. This review aims to provide an overview that will bring together researchers and clinicians to advance this burgeoning field.

Impact of sex on outcome after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.

BACKGROUND: The impact of sex on long-term outcomes after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (PH) remains unclear. We therefore examined the early and long-term outcome after PEA to determine whether sex had an impact on the risk of residual PH and need for targeted PH medical therapy. METHODS: Retrospective study of 401 consecutive patients undergoing PEA at our institution between August 2005 and March 2020 was performed. Primary outcome was the need for targeted PH medical therapy postoperatively. Secondary outcomes included survival and measures of hemodynamic improvement. RESULTS: Females (N = 203, 51%) were more likely to have preoperative home oxygen therapy (29.6% vs 11.6%, p < 0.01), and to present with segmental and subsegmental disease compared to males (49.2% vs 21.2%, p < 0.01). Despite similar preoperative values, females had higher postoperative pulmonary vascular resistance (final total pulmonary vascular resistance after PEA, 437 Dynes∙s∙cm-5 vs 324 Dynes∙s∙cm-5 in males, p < 0.01). Although survival at 10 years was not significantly different between sexes (73% in females vs 84% in males, p = 0.08), freedom from targeted PH medical therapy was lower in females (72.9% vs 89.9% in males at 5 years, p < 0.001). Female sex remained an independent factor affecting the need for targeted PH medical therapy after PEA in multivariate analysis (HR 2.03, 95%CI 1.03-3.98, p = 0.04). CONCLUSIONS: Although outcomes are excellent for both sexes, females had greater need for targeted PH medical therapy in the long-term. Early reassessment and long-term follow-up of these patients are important. Further investigations into possible mechanisms to explain the differences are warranted.

Isolation of tumour-reactive lymphocytes from peripheral blood via microfluidic immunomagnetic cell sorting.

The clinical use of tumour-infiltrating lymphocytes for the treatment of solid tumours is hindered by the need to obtain large and fresh tumour fractions, which is often not feasible in patients with unresectable tumours or recurrent metastases. Here we show that circulating tumour-reactive lymphocytes (cTRLs) can be isolated from peripheral blood at high yield and purity via microfluidic immunomagnetic cell sorting, allowing for comprehensive downstream analyses of these rare cells. We observed that CD103 is strongly expressed by the isolated cTRLs, and that in mice with subcutaneous tumours, tumour-infiltrating lymphocytes isolated from the tumours and rapidly expanded CD8+CD103+ cTRLs isolated from blood are comparably potent and respond similarly to immune checkpoint blockade. We also show that CD8+CD103+ cTRLs isolated from the peripheral blood of patients and co-cultured with tumour cells dissociated from their resected tumours resulted in the enrichment of interferon-γ-secreting cell populations with T-cell-receptor clonotypes substantially overlapping those of the patients' tumour-infiltrating lymphocytes. Therapeutically potent cTRLs isolated from peripheral blood may advance the clinical development of adoptive cell therapies.

Synergistic antitumor effects of regulatory T cell blockade combined with pemetrexed in murine malignant mesothelioma.

CD4(+)CD25(+) regulatory T cells (Tregs) can promote the growth of some tumors, but it is unknown whether this is true for all tumors, including malignant pleural mesothelioma. We have previously shown that the existence of Tregs was associated with poor survival in patients with malignant pleural mesothelioma. In this study, using an intrathoracic murine model of malignant mesothelioma (MM), we provide evidence suggesting that Treg blockade could enhance survival when combined with pemetrexed in established tumor. AC29 murine MM cells were injected into the right pleural cavity of CBA mice for tumor development. Four days after the tumor injection, tumor-bearing mice were then treated with pemetrexed alone, Treg blockade alone, or a combination of pemetrexed and Treg blockade. We observed a synergistic antitumor effect of Treg blockade combined with pemetrexed resulting in prolonged survival. The combination of Treg blockade and pemetrexed was associated with decreased tumor-infiltrating Tregs, increased IL-2 production, dendritic cell maturation, and increased CD3(+)CD8(+)IFN-gamma(+) tumor-infiltrating T cells when compared with mice treated with pemetrexed alone or Treg blockade alone. The survival benefit was abrogated if anti-CD8 mAb was administered simultaneously. Likewise, the survival benefit resulting from the combined Treg blockade with pemetrexed was not observed when immunodeficient mice were used. Therefore, this study suggests that Treg blockade combined with pemetrexed can suppress mesothelioma growth in established tumor in vivo through an immune-mediated process. This study also validates a new intrathoracic tumor model of pleural effusion to explore the role of antitumor immunity in murine MM.

[Study on the mechanism of polypeptide extract from scorpion venom to promote the restraint of cyclophosphamide on Lewis lung cancer].

OBJECTIVE: To explore the mechanism of polypeptide extract from scorpion venom (PESV) on promoting anti-tumor effects of cyclophosphamide (CTX). METHODS: The Lewis lung tumor model was established by subcutaneously implanting Lewis lung cells into C57BL/6 mice. The tumor-bearing mice were randomly divided into 4 groups, i. e., the model group, the cyclophosphamide (CTX) group, the polypeptide extract from scorpion venom (PESV) group, and the combination group (CTX + PESV), 10 mice in each group. The tumor growth curve was recorded. Changes of vascular endothelial growth factor-A (VEGF-A) and transforming growth factor-beta1 (TGF-beta1) expressions in the tumor microenvironment were detected using reverse transcription PCR and immunohistochemical assay. Changes of dendritic cells (DCs) phenotype CD80 and CD86 expressions in the tumor tissue were detected using immunofluorescence chemical assay. RESULTS: After 21 successive days of treatment, the growth of Lewis lung cancer transplantation tumor in the combination group was obviously inhibited (P<0.05). Compared with the model group,the expressions of CD80 and CD86 in the PESV group was somewhat enhanced, while those in the CTX group was somewhat lowered. Compared with the CTX group, the fluorescent signal strength and expressions in the combination group somewhat increased. Compared with the model group, the expressions of TGF-beta1 and VEGF-A mRNA decreased in the PESV group and the CTX group (both P<0.05). Compared with the PESV group and the CTX group, the expressions of TGF-beta1 and VEGF-A in the combination group both decreased (both P<0.05). CONCLUSION: PESV could inhibit the expressions of VEGF and TGF-beta1, promote the maturation of DCs, recover its antigen uptake presentation function, and reverse the immune injury to the body by CTX, thus playing a role in inducing the tumor cell apoptosis.

A panel of emerging EMT genes identified in malignant mesothelioma.

Malignant mesothelioma (MESO) is a highly aggressive cancer with poor prognosis. Epithelial-mesenchymal transition (EMT) is a critical process in malignancies involved in tumor angiogenesis, progression, invasion and metastasis, immunosuppressive microenvironment and therapy resistance. However, there is a lack of specific biomarkers to identify EMT in MESO. Biphasic MESO with dual phenotypes could be an optimal model to study EMT process. Using a powerful EMTome to investigate EMT gene signature, we identified a panel of EMT genes COL5A2, ITGAV, SPARC and ACTA2 in MESO. In combination with TCGA database, Timer2.0 and other resources, we observed that overexpression of these emerging genes is positively correlated with immunosuppressive infiltration, and an unfavorable factor to patient survival in MESO. The expression of these genes was confirmed in our patients and human cell lines. Our findings suggest that these genes may be novel targets for therapeutics and prognosis in MESO and other types of cancers.

Heterogeneous RNA editing and influence of ADAR2 on mesothelioma chemoresistance and the tumor microenvironment.

We previously observed increased levels of adenosine-deaminase-acting-on-dsRNA (Adar)-dependent RNA editing during mesothelioma development in mice exposed to asbestos. The aim of this study was to characterize and assess the role of ADAR-dependent RNA editing in mesothelioma. We found that tumors and mesothelioma primary cultures have higher ADAR-mediated RNA editing compared to mesothelial cells. Unsupervised clustering of editing in different genomic regions revealed heterogeneity between tumor samples as well as mesothelioma primary cultures. ADAR2 expression levels are higher in BRCA1-associated protein 1 wild-type tumors, with corresponding changes in RNA editing in transcripts and 3'UTR. ADAR2 knockdown and rescue models indicated a role in cell proliferation, altered cell cycle, increased sensitivity to antifolate treatment, and type-1 interferon signaling upregulation, leading to changes in the microenvironment in vivo. Our data indicate that RNA editing contributes to mesothelioma heterogeneity and highlights an important role of ADAR2 not only in growth regulation in mesothelioma but also in chemotherapy response, in addition to regulating inflammatory response downstream of sensing nucleic acid structures.