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Malignant Mesothelioma multicellular spheroids: mechanism of multicellular resistance
Author(s) -
Barbone Dario,
Abayasiriwardana Keith,
Arcega Ramir,
Wilson Shan,
Broaddus V. Courtney
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a227-a
Subject(s) - mesothelioma , pi3k/akt/mtor pathway , apoptosis , spheroid , cancer research , protein kinase b , microbiology and biotechnology , paclitaxel , cell , chemistry , multicellular organism , biology , cancer , in vitro , medicine , pathology , biochemistry , genetics
Malignant mesothelioma is an aggressive cancer resistant to standard chemotherapies. Clinically relevant models to study the apoptotic resistance of this tumor are needed. Three‐dimensional cell structures are emerging as a critical model of apoptotic resistance because cells in a three‐dimensional architecture gain a high level of resistance to a variety of insults. Therefore, we investigated the apoptotic resistance of mesothelioma cells in three‐dimensional cell structures called multicellular spheroids. Mesothelioma cells (M28 and REN, 10,000/well) were allowed to grow on non‐adherent 96‐well round bottomed plates, where they attached to each other to form multicellular spheroids. Mesothelioma cells, grown as spheroids, were highly resistant to death receptor ligands and to chemotherapy compared to their monolayer counterpart, acquiring the resistance as early as 6 h after plating. Interestingly we found that survival pathways like PI3K/Akt/mTOR were substantially downregulated in cells during spheroid formation over 24 h. And yet, despite the low activity of these pathways, inhibitors of these survival pathways, like LY294002 and rapamycin, were still able to block apoptotic resistance. We found that these pathways, while downregulated in the spheroids at baseline, were rapidly and significantly induced by the treatments. Thus, resistance in three‐dimensional structures may depend on survival pathways that are constitutively downregulated but rapidly activated by external stresses. This research was supported by an NIH RO1 NCI‐095671 to VCB and a Buzzi Foundation grant to DB.