Malignant Peritoneal Mesothelioma Cell Research Articles

Abstract 1329: Aging increases malignant peritoneal mesothelioma metastasis

Abstract Mesothelioma is a rare cancer with approximately 3,000 new cases each year. There are three types of mesotheliomas including pleural (75%), pericardial (>1%) and peritoneal (20%). Mesothelioma occurs in the mesothelial cells, which form a protective barrier to multiple organs. Malignant peritoneal mesothelioma (MPM) is initiated in the peritoneum, a serous membrane that lines the inner walls of the abdominal cavity and the outside of the visceral organs and is a very receptive environment for malignancy and metastasis. MPM metastasizes to the abdominal cavity, affecting the omentum, liver, stomach, intestines, and kidneys. MPM is extremely difficult to diagnose due to its vague symptoms, such as abdominal distension, abdominal pain, weight loss, and nausea. Due to difficulty in diagnosis, most patients are diagnosed at an advanced disease (stage III or IV) with a very poor prognosis with a 9% 5-year survival rate. Asbestos exposure is a major risk factor for MPM with symptoms taking 20-50 years post- exposure to appear, making MPM prominent in aged adults. Mesothelin (MSLN), a 40 kDa protein, is normally expressed on the surface of mesothelial cells and manifests at abnormally high levels in several carcinomas including malignant peritoneal mesothelioma. The exact role of mesothelin is not yet fully understood as mesothelin knockout mice do not display an abnormal phenotype. However, there is some evidence to suggest that mesothelin is involved in tumor cell adhesion by binding to the tumor antigen MUC16. Mesothelin wild-type (WT) and knockout (KO) mice were used to investigate the role of host mesothelin expression on MPM metastasis. A MPM cell line was tagged with nuclear red fluorescence protein (RFP) and injected into the abdomen of female C57Bl/6, young (3-6 months) and aged (18-23 months), MSLN WT or KO mice. Disease progression was evaluated post injection of tumor cells by fluorescent in vivo imaging prior to end point dissection. The abdominal cavity was imaged in situ and tumor burden was evaluated using Image J. Overall, aged mice had increased abdominal tumor burden regardless of host MSLN expression. Aged MSLN KO mice displayed an increase in abdominal tumor burden compared to aged MSLN WT mice, however this difference was not significant. Interestingly, the immune profile of the abdominal cavity of tumor naive mice displays a decrease in natural killer (NK) cells and peritoneal macrophages in aged mice suggesting a role in regulating metastatic peritoneal mesothelioma and could possibly be targets for new immunotherapies. This study demonstrates host age increases tumor growth and metastatic success in peritoneal mesothelioma. Citation Format: Mykayla Miller. Aging increases malignant peritoneal mesothelioma metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1329.

Establishment and characterization of a new malignant peritoneal mesothelioma cell line, KOG-1, from the ascitic fluid of a patient with pemetrexed chemotherapy resistance.

Malignant peritoneal mesothelioma (MPeM) is a rare and aggressive form of malignant mesothelioma. Sufficient biological tools for studying the functional characteristics of this cancer have not been developed. Therefore, in this study, a novel human cancer cell line, KOG-1, was established from ascites fluids isolated from a 39-year-old Japanese woman with pemetrexed-resistant MPeM. Cells were dendritic or linear immediately after thawing, showed a jigsaw puzzle-like and spindle arrangement during growth, and formed monolayers without contact inhibition in two-dimensional (2D) culture. The population doubling time was 13.7h. Karyotypic and molecular genetic analyses showed that chromosome numbers ranged from 62 to 142, with a peak of 73 with complicated copy number alterations. No germline BAP1 pathogenic variant was detected. Cells expressed various tumor markers of mesothelioma, such as calretinin, podoplanin, and Wilms tumor 1 (WT-1). Drug sensitivity and resistance testing with a set of 36 drugs using 2D and three-dimensional (3D) culture models demonstrated that KOG-1 cells showed high and low sensitivity to pemetrexed under 2D and 3D culture conditions, respectively, whereas control ovarian cancer cell lines showed low sensitivity to pemetrexed under both culture conditions. This newly established cell line will be a valuable biological resource to expand the feasibility of functional studies as well as drug testing for potential therapeutic purposes in MPeM.

MiR-380-5p-mediated repression of TEP1 and TSPYL5 interferes with telomerase activity and favours the emergence of an \u201cALT-like\u201d phenotype in diffuse malignant peritoneal mesothelioma cells

BackgroundUnderstanding the molecular/cellular underpinnings of diffuse malignant peritoneal mesothelioma (DMPM), a fatal malignancy with limited therapeutic options, is of utmost importance for the fruitful management of the disease. In this context, we previously found that telomerase activity (TA), which accounts for the limitless proliferative potential of cancer cells, is prognostic for disease relapse and cancer-related death in DMPM patients. Consequently, the identification of factors involved in telomerase activation/regulation may pave the way towards the development of novel therapeutic interventions for the disease. Here, the capability of miR-380-5p, a microRNA negligibly expressed in telomerase-positive DMPM clinical specimens, to interfere with telomerase-mediated telomere maintenance and, hence, with cancer cell growth was assessed on preclinical models of DMPM.MethodsDMPM cells were transfected with a miR-380-5p synthetic precursor, and the effects of miRNA replacement were evaluated in terms of growing capability, induction of apoptosis and interference with TA. Reiterated weekly transfections were also performed in order to analyse the phenotype arising upon prolonged miR-380-5p reconstitution in DMPM cells.ResultsThe ectopic expression of miR-380-5p elicited a remarkable inhibition of TA and resulted in DMPM cell growth impairment and apoptosis induction. In particular, we demonstrated for the first time that these effects were the result of a molecular circuitry converging on telomerase associated protein 1 (TEP1), where the miRNA was able to target the gene both directly in unconventional targeting modality and indirectly via p53 accumulation consequent to miRNA-mediated downregulation of testis-specific protein, Y-encoded-like 5 gene. Moreover, miR-380-5p did not cause telomere attrition and cell growth arrest in long-term DMPM transfectants, which in turn showed slightly elongated telomeres and molecular features (e.g. c-circle DNA and reduced expression levels of chromatin remodeler ATRX) resembling an alternative lengthening of telomeres (ALT) phenotype.ConclusionsmiR-380-5p interferes with TA in DMPM cells by targeting TEP1. Notably, in the long-term setting, miR-380-5p-mediated impairment of TA did not result in telomere attrition. Instead, a phenotype reminiscent of ALT emerged in DMPM cells as possible compensatory pathway that safeguards DMPM cell growth, an event that may be regarded as a potential resistance mechanism to anticancer therapies based on telomerase inhibitors.

Abstract 643: Establishment and mutation analysis of a novel malignant peritoneal mesothelioma cell line, TU-MM-1

Abstract Malignant peritoneal mesothelioma (MPM) is a rare aggressive neoplasm of the peritoneum, and its molecular biological characteristics and mechanisms of development are poorly understood. We, therefore, established a new cell line of human MPM, TU-MM-1, to elucidate its biological properties and to develop novel therapeutic strategies. The cells showed polygonal morphology, grew in monolayers without contact inhibition and were arranged like a jigsaw puzzle. The chromosome numbers ranged from 41 to 44. A low rate of proliferation was observed and the doubling time was 67.9 h. Genomic DNA sequencing revealed that TU-MM-1 cells harbored missense mutations in APC, LATS2, BRCA1/2, and TP53, and mutation of a splice donor site in BAP1 and loss of CDKN2A gene. We observed the absence of BAP1 and p16INK4a proteins, underexpression of LATS2 protein, and overexpression of p53 protein in TU-MM-1 cells in western blot analysis. Heterotransplantation to nude mice produced tumors that had the characteristics of the original tumor. This cell line may be useful for studying biological properties and contribute to novel treatment strategies. Citation Format: Seiya Sato, Nao Oumi, Hiroaki Itamochi, Tetsuro Oishi, Tasuku Harada, Toru Sugiyama. Establishment and mutation analysis of a novel malignant peritoneal mesothelioma cell line, TU-MM-1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 643.

Establishment and mutation analysis of a novel malignant peritoneal mesothelioma cell line, TU-MM-1, using whole genome sequencing.

A new cell line of human malignant peritoneal mesothelioma (MPM), TU-MM-1, was established and characterized. The cells showed polygonal morphology, grew in monolayers without contact inhibition and were arranged like a jigsaw puzzle. The chromosome numbers ranged from 41 to 44. A low rate of proliferation was observed and the doubling time was 67.9 h. Genomic DNA sequencing revealed that TU-MM-1 cells harbored missense mutations in APC, LATS2, BRCA1/2, and TP53, and mutation of a splice donor site in BAP1 and loss of CDKN2A gene. We observed the absence of BAP1 and p16(INK4a) proteins, underexpression of LATS2 protein, and overexpression of p53 protein in TU-MM-1 cells in western blot analysis. Heterotransplantation to nude mice produced tumors that had the characteristics of the original tumor. This cell line may be useful for studying biological properties and contribute to novel treatment strategies.

Oncolytic Vaccinia Virus as an Adjuvant Treatment to Cytoreductive Surgery for Malignant Peritoneal Mesothelioma

Malignant peritoneal mesothelioma (MPM) is an aggressive cancer with a dismal prognosis. Oncolytic viruses are a promising new therapy for cancer because of their ability to kill tumor cells with minimal toxicity to normal tissues. This experimental study aimed to examine the potential of modified vaccinia virus (VV) to treat MPM when administered alone or as an adjuvant treatment to surgery. Two aggressive murine mesothelioma cell lines (AC29, AB12), were used. Cell viability and viral cytopathic effects were assessed using MTS and crystal violet assays. Immunocompetent mice were injected intraperitoneally with MPM cells and treated with intraperitoneal VV. Tumor-bearing mice also underwent cytoreductive surgery (CRS) followed by VV (or control) therapy. The cytotoxic effects of VV on MPM cell lines was significantly increased compared with the control non-cancer cell line. In both orthotopic models, VV induced tumor regression, prolonging median and long-term survival. VV treatment after incomplete CRS was not superior to VV alone; however, when mice with microscopic disease were treated with VV, further prolongation of median and long-term survivals was observed. VV selectively kills MPM cells in vitro and leads to improved survival and cures in immunocompetent murine models. Higher efficacy of the virus in the microscopic disease context suggests the use of the virus as an adjuvant treatment to complete surgical resection. These promising results justify further studies of VV in humans as a novel treatment for MPM.

Anticancer effect of bromelain with and without cisplatin or 5-FU on malignant peritoneal mesothelioma cells

Malignant peritoneal mesothelioma (MPM) is a rare neoplasm of the peritoneum, causally related to asbestos exposure. Nonspecific symptoms with a late diagnosis results in poor survival (<1 year). Treatment with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy has improved survival in some patients (median 3-5 years). Hence, new therapies are urgently needed. MUC1 is a glycosylation-dependent protein that confers tumours with invasiveness, metastasis and chemoresistance. Bromelain (cysteine proteinase) hydrolyses glycosidic bonds. Therefore, we investigated the antitumour effect of bromelain on MUC1-expressing MPM cell lines. MUC1 expressions in cells were assessed using immunofluorescent probes with cells grown on cover slips and western blot analysis on cell lysates. The cell lines were treated with various concentrations of bromelain and after 4 and 72 h, their viability was assessed using standard sulforhodamine assays. The cells were also treated with combinations of bromelain and cytotoxic drugs (cisplatin or 5-FU) and their viability was assessed at 72 h. Finally, with western blotting, the effects of bromelain on cellular survival proteins were investigated. PET cells expressed more MUC1 compared with YOU cells. The cell viability of both PET and YOU cells was adversely affected by bromelain, with PET cells being slightly resistant. The addition of bromelain increased the cytotoxicity of cisplatin significantly in both cell lines. However, 5-FU with bromelain did not show any significant increase in cytotoxicity. Bromelain-induced cell death is by apoptosis and autophagy. Bromelain has the potential of being developed as a therapeutic agent in MPM.

Anticancer Property of Bromelain With Therapeutic Potential in Malignant Peritoneal Mesothelioma

Bromelain is a mixture of proteolytic enzymes that is capable of hydrolyzing glycosidic linkages in glycoprotein. Glycoprotein's are ubiquitously distributed throughout the body and serve a variety of physiologic functions. Faulty glycosylation of proteins may lead to cancer. Antitumor properties of bromelain have been demonstrated in both, in vitro and in vivo studies, along with scanty anecdotal human studies. Various mechanistic pathways have been proposed to explain the anticancer properties of bromelain. However, proteolysis by bromelain has been suggested as a main pathway by some researchers. MUC1 is a glycoprotein that provides tumor cells with invasive, metastatic, and chemo-resistant properties. To date, there is no study that examines the effect of bromelain on MUC1. However, the viability of MUC1 expressing pancreatic and breast cancer cells are adversely affected by bromelain. Further, the efficacy of cisplatin and 5-FU are enhanced by adjuvant treatment with bromelain, indicating that the barrier function of MUC1 may be affected. Other studies have also indicated that there is a greater accumulation of 5-FU in the cell compartment on treatment with 5-FU and bromelain. Malignant peritoneal mesothelioma (MPM) expresses MUC1 and initial studies have shown that the viability of MPM cells is adversely affected by exposure to bromelain. Further, bromelain in combination with either 5-FU or cisplatin, the efficacy of the chemotherapeutic drug is enhanced. Hence, current evidence indicates that bromelain may have the potential of being developed into an effective anticancer agent for MPM.

Activation of the phosphoinositide‐3‐kinase and mammalian target of rapamycin signaling pathways are associated with shortened survival in patients with malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma (MPM) is a rare malignancy of the serosal membranes of the abdominal cavity. This cancer is ultimately fatal in almost all afflicted individuals; however, there is marked variability in its clinical behavior: Some patients die rapidly, and others survive for many years. In the current study, the authors investigated the molecular nature of MPM to obtain insights into the heterogeneity of its clinical behavior and to identify new therapeutic targets for intervention. Fresh pretreatment tumor samples were collected from 41 patients with MPM who underwent surgical cytoreduction and received regional intraoperative chemotherapy perfusion. From those samples, gene expression analyses were performed. The major cellular pathways that were identified in this cancer were inhibited using a pathway-specific inhibitor. Unsupervised clustering of genes identified 2 distinct groups of patients with significantly different survivals (Group A: median survival, 24 months; Group B: median survival, 69.5 months; P = .035). Phosphoinositide-3-kinase (PI3K) and the closely interacting mammalian target of rapamycin (mTOR) signaling pathways were overexpressed predominantly in the poor survival group; and the genes of these pathways, phosphoinositide-3-kinase, catalytic, α polypeptide (PIK3CA) and rapamycin-insensitive companion of mammalian target of rapamycin (RICTOR), were highly significantly predictive of shortened patient survival in Group A. The role of these pathways in MPM tumor progression was also investigated by treating 2 MPM cell lines with BEZ235, a dual-class PI3K and mTOR inhibitor, and the authors observed significant inhibition of downstream cell signaling and cell proliferation. Taken together, the results from this study revealed that, based on gene expression profiles, there were 2 distinct patient groups with significantly different survival and that targeting the PI3K and mTOR signaling pathways may have significant therapeutic value in patients with MPM.

Survivin is Highly Expressed and Promotes Cell Survival in Malignant Peritoneal Mesothelioma

Background: The biology of malignant peritoneal mesothelioma (MPM) is largely unknown. In the present study, we assessed the expression of survivin and other members of the inhibitors of apoptosis proteins (IAP) family (IAP-1, IAP-2 and X-IAP) in a series of 32 MPM surgical specimens and investigated the effects of survivin knockdown in an established MPM cell line. Methods: Expression of different IAPs was measured by immunohistochemistry. MPM cells were transfected with a small-interfering RNA (siRNA) targeting survivin mRNA and analyzed for survivin expression, growth rate, and ability to undergo spontaneous and drug (cisplatin, doxorubicin)-induced apoptosis. Results: Survivin expression was observed in 29 (91%) surgical MPM specimens, whereas the positivity rate for the other IAPs ranged from 69% to 100%. Transfection of MPM cells with the survivin siRNA induced a marked inhibition of survivin protein expression, a time-dependent decline in cell growth and an enhanced rate of spontaneous and drug-induced apoptosis, with a concomitant increase in the catalytic activity of caspase-9. Conclusion: Our results show for the first time that survivin, as well as other IAPs, is largely expressed in clinical MPMs and suggest that strategies aimed at down-regulating survivin may provide a novel approach for the treatment of the malignancy.

Potentiation of cisplatin and carboplatin cytotoxicity by amphotericin B in different human ovarian carcinoma and malignant peritoneal mesothelioma cells.

An in vitro study of the combined cytotoxicity of either cisplatin (CDDP) or carboplatin and amphotericin B (AmB) was undertaken on a set of different ovarian carcinoma (IGROVI, IGROVI-C10, OAW42) and peritoneal malignant mesothelioma (CFB-CARP1) cell lines and ascitic cells freshly obtained from ovarian cancer patients so as to investigate the possibility of overcoming their resistance to platinum compounds. Growth-inhibition curves obtained 6 days after a 2-h period of exposure to the drugs showed that AmB at 5-10 mg/l allowed a 5- to 10-fold decrease in the 50% growth-inhibitory concentrations (IC50) of CDDP and carboplatin on either sensitive or resistant cells. Intracellular platinum assays with IGROVI cells showed that AmB acted by increasing dramatically the platinum uptake at a proportion that accounted for the increase in cytotoxicity. In the subline IGROVI-C10, a 10-fold resistant subline of IGROVI, AmB at 10 mg/l allowed recovery to the level of sensitivity seen in the parental cell line in the absence of AmB but not to the level observed in the presence of AmB. Acquisition of resistance mechanisms that are independent of the regulation of platinum uptake might be involved in this cell line. Thus, AmB might act by increasing the intracellular concentration of platinum without modifying the resistance mechanism involved downstream. However, in our models an increase in the intracellular level of platinum was always sufficient for the recovery of chemosensitivity in vitro. We also show that the phosphodiesterase inhibiting methylxanthines act synergistically with AmB. The latter drugs are weakly toxic and could also attenuate the nephrotoxicity of AmB.