Phagocytosis of dying tumor cells by human peritoneal mesothelial cells

Abstract

SummaryPeritoneal carcinomatosis is an advanced form of metastatic disease characterized by cancer cell dissemination onto the peritoneum. It is commonly observed in ovarian and colorectal cancers and is associated with poor patient survival. Novel therapies consist of cytoreductive surgery in combination with intraperitoneal chemotherapy, aiming at tumor cell death induction. The resulting dying tumor cells are considered to be eliminated by professional as well as semi-professional phagocytes. In the present study, we have identified a hitherto unknown type of 'amateur' phagocyte in this environment: human peritoneal mesothelial cells (HMCs). We demonstrate that HMCs engulf corpses of dying ovarian and colorectal cancer cells, as well as other types of apoptotic cells. Flow cytometric, confocal and electron microscopical analyses revealed that HMCs ingest dying cell fragments in a dose-and timedependent manner and the internalized material subsequently traffics into late phagolysosomes. Regarding the mechanisms of prey cell recognition, our results show that HMCs engulf apoptotic corpses in a serum-dependent and -independent fashion and quantitative real-time PCR (qRT-PCR) analyses revealed that diverse opsonin receptor systems orchestrating dying cell clearance are expressed in HMCs at high levels. Our data strongly suggest that HMCs contribute to dying cell removal in the peritoneum, and future studies will elucidate in what manner this influences tumor cell dissemination and the antitumor immune response.

HSP90 inhibition as a means of radiosensitizing resistant, aggressive soft tissue sarcomas

“…Transcriptomic profiling of crucial DNA damage response regulators was performed by quantitative realtime RT-PCR (qRT-PCR) analyses as described previously [13,14]. Briefly, total RNA was extracted with the NucleoSpin RNA II Kit (Macherey & Nagel, Dueren, Germany).…”

Milk fat globule-EGF factor 8 mediates the enhancement of apoptotic cell clearance by glucocorticoids

“…QRT-PCR analysis was performed using the ABI Prism 7000 Sequence Detection System (Applied Biosystems, Foster City, CA, USA) and Maxima qPCR Mastermix (Fermentas, St. Leon-Rot, Germany) as described. [49][50][51] The following primers and probes were used (MWG Biotech, Ebersberg, Germany): human MFG-E8 forward 5 0 -GCACTCTGCGCTTTGAGC TA-3 0 , human MFG-E8 reverse 5 0 -TTGTCAGGGATGCTGTTATTCTTC-3 0 ; human Anx A1 forward 5 0 -GCCCCTATCCTACCTTCAATCC-3 0 , human Anx A1 reverse 5 0 -CATCCACACCTTTAACCATTATGG-3 0 ; human Del-1 forward 5 0 -CAGGCGAAT TTATGGGAAGAAA-3 0 , human Del-1 reverse 5 0 -TGCTGGTTTGATATAATTCCAC CTT-3 0 ; mouse MFG-E8 forward 5 0 -AAAGCTGTACCCTGTTTCGTGC-3 0 , mouse MFG-E8 reverse 5 0 -GGAGGCTGACATCTGGCTGT-3 0 ; human/mouse 18 S rRNA forward 5 0 -CGGCTACCACATCCAAGGAA-3 0 , human/mouse 18 S rRNA reverse 5 0 -GCTGGAATTACCGCGGCT-3 0 , human/mouse 18 S rRNA probe JOE-5 0 -TGCT GGCACCAGACTTGCCCTC-3 0 -TAMRA. Total RNA from B2 Â 10 6 cells was extracted with the NucleoSpin RNA II-Kit (Macherey and Nagel, Dueren, Germany).…”

Serum-Derived Plasminogen Is Activated by Apoptotic Cells and Promotes Their Phagocytic Clearance

“…Phagocytosis was measured, as described previously (7,11). Briefly, 1 3 10 7 prey cells/ml were labeled with 2 mM PKH26 in diluent C (Sigma-Aldrich) for 5 min at room temperature, according to the manufacturer's instructions.…”