Abstract
Multicellular contact has been shown to influence the in vitro sensitivity of cells to drug treatment. We investigated the use of macroporous gelatin microcarriers, CultiSpher-G, as a convenient laboratory system for the molecular analysis of this “contact effect”. We determined that human A549 cells can be grown in CultiSphers with growth and cell cycle parameters similar to those of monolayers. In addition, cells in CultiSphers express less p27/kip1, an indicator of cell cycle arrest, than equivalent cells in monolayers. When treated with drugs, A549 cells grown in CultiSphers or monolayers accumulate equivalent amounts of platinum-DNA adducts and similar amounts of doxorubicin. Moreover, A549 and KB-3-1 cells in CultiSphers have significantly decreased sensitivity tocis-platinum(II)diammine dichloride (cisplatin), 4-hydroperoxycyclophosphamide, doxorubicin, and paclitaxel (taxol) compared with cells in monolayers when assayed by clonogenic survival. Cisplatin treatment in monolayers or CultiSphers did not result in apoptotic cell death. In contrast, paclitaxel caused a significant amount of sub-G1 DNA, an indicator of apoptosis, which was diminished when cells were grown in CultiSphers compared with monolayers. When grown in CultiSphers, cells with abrogated p53 function (A549/16E6 and NCI-H1299) were less sensitive to cisplatin than the corresponding monolayer cells, indicating that the decrease in sensitivity is p53 independent. Taken together, the data suggest that CultiSpher-G microcarriers are a useful in vitro system to examine the effects of three-dimensional cell contact on drug sensitivity of human tumor cells.
Footnotes
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Send reprint requests to: Dr. Marilyn M. Cornwell, Fred Hutchinson Cancer Center, Mail Stop D2–100, 1100 Fairview Ave. N., Seattle, WA 98109. E-mail: mcornwel{at}fhcrc.org
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↵1 These authors contributed equally to this manuscript.
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↵2 Current address: Childrens Center for Cancer and Blood Diseases, Childrens Hospital Los Angeles Research Institute, MS 57, 4650 Sunset Blvd., Los Angeles, CA 90027.
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This work was supported by Public Health Service Grant RO1 CA63419 (to M.M. Cornwell). J. Rasey was supported by National Institutes of Health (NIH) Grant R37 CA34570. B. Maurer was supported by NIH training Grant T32 CA 09351. M. Ihnat was supported by NIH training Grant T32 DK07742–02 through the University of Washington School of Medicine, Department of Gastroenterology.
- Abbreviations:
- 4-HC
- 4-hydroperoxycyclophosphamide
- cisplatin
- cis-platinum(II)diammine dichloride
- Pt-DNA
- platinum-DNA
- TBST
- 10 mM Tris-HCl, pH 8, 150 mM NaCl, 0.5% Tween 20, p27, p27/kip1
- MTS
- 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy methyoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium
- Received August 27, 1998.
- Accepted February 12, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
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