Pleural Mesothelial Cell (PMC) Defense Mechanisms Against Malignancy

Abstract

Tumors such as ovarian, lung, and breast have been found to have a predilection for the pleura. Pleural mesothelial cells (PMCs) play an active role in pleural inflammation via release of cytokines. However, mechanisms whereby PMCs defend themselves against invading malignant cells are unknown. In the present study, we hypothesized that PMCs release the antiangiogenic factor endostatin and inhibit malignant cell invasion. We evaluated the endostatin levels in malignant (MAL) and congestive heart failure (CHF) pleural fluids (PF). Endostatin expression by PMC was also demonstrated by Western analysis and confocal microscopy. Our results demonstrate that CHF PF contained significantly higher levels of endostatin when compared with MAL PF. PMCs alone released a significantly greater amount of endostatin when compared with ovarian cancer cells (OCCs). When the PMC were cocultured with OCCs without contact, there was an increase in the endostatin production. However, when the PMCs were cocultured in direct contact with OCCs the endostatin levels significantly decreased. Endostatin production was upregulated in the presence of tumor cells but not when OCCs were adherent to underlying PMC monolayer. Immunofluorescent staining of PMCs for endostatin correlated with endostatin release. These findings suggest that PMCs play a key role in the antiangiogenesis process by producing endostatin in the pleural space, and thus preventing tumor spread and metastasis in the pleura.

Talc mediates angiostasis in malignant pleural effusionsviaendostatin induction

“…The present authors have previously demonstrated that cancer cells induce PMC to release VEGF [32]. However, a normal mesothelium is critical in maintaining the dynamic balance of angiogenic versus antiangiogenic factors [19,32]. The present authors' model clearly demonstrate that malignant cells growing on the pleural surface gain metastatic potential by inducing the production of VEGF, thus creating a pro-angiogenic milieu in the pleural space [32].…”

“…Endostatin is a 20-kDa fragment of collagen XVIII that specifically inhibits endothelial cell migration, and induces cell cycle arrest, apoptosis, and reduces tumour growth [18]. The present authors recently reported that PMC release endostatin and invading tumour cells enhance the production of endostatin in PMCs [19]. In the present study, the authors hypothesise that talc induces PMC to release the anti-angiogenic factor, endostatin, and that this may modulate malignant growth on the pleura by tilting the pro-angiogenic environment of the pleural space to an anti-angiogenic milieu.…”

Talc mediates angiostasis in malignant pleural effusionsviaendostatin induction

“…The present authors have previously demonstrated that cancer cells induce PMC to release VEGF [32]. However, a normal mesothelium is critical in maintaining the dynamic balance of angiogenic versus antiangiogenic factors [19,32]. The present authors' model clearly demonstrate that malignant cells growing on the pleural surface gain metastatic potential by inducing the production of VEGF, thus creating a pro-angiogenic milieu in the pleural space [32].…”

“…Endostatin is a 20-kDa fragment of collagen XVIII that specifically inhibits endothelial cell migration, and induces cell cycle arrest, apoptosis, and reduces tumour growth [18]. The present authors recently reported that PMC release endostatin and invading tumour cells enhance the production of endostatin in PMCs [19]. In the present study, the authors hypothesise that talc induces PMC to release the anti-angiogenic factor, endostatin, and that this may modulate malignant growth on the pleura by tilting the pro-angiogenic environment of the pleural space to an anti-angiogenic milieu.…”

Ephrin-A1 inhibits NSCLC tumor growth via induction of Cdx-2 a tumor suppressor gene

“…NSCLC cells were cultured in 60 mm size cell culture dishes (Fisher Scientific, Pittsburgh, VA) to confluence and the cells were lysed in lysis buffer with the method reported earlier [26]. Protein was estimated by BCA method (PIERCE, Rockford, IL) and equal amount of protein (20 μg/lane) were loaded.…”

Targeting the early steps of Aβ16–22 protofibril disassembly by N‐methylated inhibitors: A numerical study

“…The medium was changed on alternate days. The mesothelial cells were characterized by the presence of classic cobblestone morphology, the absence of factor VIII antigen, and the presence of cytokeratin, as reported previously 18. When the cells were confluent, they were trypsinized and seeded into culture flasks/transwell chambers as required for different assays.…”

“…To evaluate EphA2 receptor expression in MMCs and PMCs, the cells were analyzed by using confocal laser‐scanning microscopy (Zeiss LSM 510, Axiovert 100M; Zeiss, Thornwood, NY), as reported previously 18. In brief, the cells were cultured to confluence on gelatinized glass coverslips and fixed in 5% paraformaldehyde (with 50 mM phosphate buffer) in 50% Tris wash buffer (TWB).…”

Talc mediates angiostasis in malignant pleural effusionsviaendostatin induction

“…The present authors have previously demonstrated that cancer cells induce PMC to release VEGF [32]. However, a normal mesothelium is critical in maintaining the dynamic balance of angiogenic versus antiangiogenic factors [19,32]. The present authors' model clearly demonstrate that malignant cells growing on the pleural surface gain metastatic potential by inducing the production of VEGF, thus creating a pro-angiogenic milieu in the pleural space [32].…”

“…Endostatin is a 20-kDa fragment of collagen XVIII that specifically inhibits endothelial cell migration, and induces cell cycle arrest, apoptosis, and reduces tumour growth [18]. The present authors recently reported that PMC release endostatin and invading tumour cells enhance the production of endostatin in PMCs [19]. In the present study, the authors hypothesise that talc induces PMC to release the anti-angiogenic factor, endostatin, and that this may modulate malignant growth on the pleura by tilting the pro-angiogenic environment of the pleural space to an anti-angiogenic milieu.…”

Ephrin-A1 inhibits NSCLC tumor growth via induction of Cdx-2 a tumor suppressor gene

“…NSCLC cells were cultured in 60 mm size cell culture dishes (Fisher Scientific, Pittsburgh, VA) to confluence and the cells were lysed in lysis buffer with the method reported earlier [26]. Protein was estimated by BCA method (PIERCE, Rockford, IL) and equal amount of protein (20 μg/lane) were loaded.…”

Targeting the early steps of Aβ16–22 protofibril disassembly by N‐methylated inhibitors: A numerical study

“…The medium was changed on alternate days. The mesothelial cells were characterized by the presence of classic cobblestone morphology, the absence of factor VIII antigen, and the presence of cytokeratin, as reported previously 18. When the cells were confluent, they were trypsinized and seeded into culture flasks/transwell chambers as required for different assays.…”

“…To evaluate EphA2 receptor expression in MMCs and PMCs, the cells were analyzed by using confocal laser‐scanning microscopy (Zeiss LSM 510, Axiovert 100M; Zeiss, Thornwood, NY), as reported previously 18. In brief, the cells were cultured to confluence on gelatinized glass coverslips and fixed in 5% paraformaldehyde (with 50 mM phosphate buffer) in 50% Tris wash buffer (TWB).…”

Talc mediates angiostasis in malignant pleural effusionsviaendostatin induction

“…The present authors have previously demonstrated that cancer cells induce PMC to release VEGF [32]. However, a normal mesothelium is critical in maintaining the dynamic balance of angiogenic versus antiangiogenic factors [19,32]. The present authors' model clearly demonstrate that malignant cells growing on the pleural surface gain metastatic potential by inducing the production of VEGF, thus creating a pro-angiogenic milieu in the pleural space [32].…”

“…Endostatin is a 20-kDa fragment of collagen XVIII that specifically inhibits endothelial cell migration, and induces cell cycle arrest, apoptosis, and reduces tumour growth [18]. The present authors recently reported that PMC release endostatin and invading tumour cells enhance the production of endostatin in PMCs [19]. In the present study, the authors hypothesise that talc induces PMC to release the anti-angiogenic factor, endostatin, and that this may modulate malignant growth on the pleura by tilting the pro-angiogenic environment of the pleural space to an anti-angiogenic milieu.…”

Ephrin-A1 inhibits NSCLC tumor growth via induction of Cdx-2 a tumor suppressor gene

“…NSCLC cells were cultured in 60 mm size cell culture dishes (Fisher Scientific, Pittsburgh, VA) to confluence and the cells were lysed in lysis buffer with the method reported earlier [26]. Protein was estimated by BCA method (PIERCE, Rockford, IL) and equal amount of protein (20 μg/lane) were loaded.…”

Targeting the early steps of Aβ16–22 protofibril disassembly by N‐methylated inhibitors: A numerical study

“…The medium was changed on alternate days. The mesothelial cells were characterized by the presence of classic cobblestone morphology, the absence of factor VIII antigen, and the presence of cytokeratin, as reported previously 18. When the cells were confluent, they were trypsinized and seeded into culture flasks/transwell chambers as required for different assays.…”

“…To evaluate EphA2 receptor expression in MMCs and PMCs, the cells were analyzed by using confocal laser‐scanning microscopy (Zeiss LSM 510, Axiovert 100M; Zeiss, Thornwood, NY), as reported previously 18. In brief, the cells were cultured to confluence on gelatinized glass coverslips and fixed in 5% paraformaldehyde (with 50 mM phosphate buffer) in 50% Tris wash buffer (TWB).…”