Multicellular layers (MCL) of cancer cells is an in vitro 3-dimensional (3D) model that mimics avascular microregions of human solid tumors and has been shown to be useful in pharmacokinetic-pharmacodynamic studies of anticancer agents. We investigated whether Ki-67, which is widely used as a proliferation marker, can be used to evaluate changes in proliferative fractions following drug exposure in MCL of HT-29 human colorectal cancer cells. Ki-67 expression was monitored and compared between cancer cells cultured as monolayers or MCL. Drug distribution and Ki-67 expression were evaluated within MCL following exposure to doxorubicin and paclitaxel. Ki-67 expression was observed in the nuclei of proliferating cells in monolayers, tumor xenograft, and multicellular spheroids. In MCL, however, Ki-67 expression was detected in the membrane/cytoplasm as well as in the nucleus throughout MCL. Neither the location nor the level of expression changed following drug exposure, whereas drug-induced apoptosis increased. Our data show that membranous/cytoplasmic Ki-67 may not be valid as a marker for the proliferative activity of cells grown as MCL. Studies for non-nuclear localization and its mechanism in 3D in vitro models of other cell lines are warranted.
Bibliographical noteFunding Information:
Acknowledgments This work was supported by Mid-career Researcher Program through NRF Grant funded by the MEST (No. 2012R1A2A2A01003361) and the Nano-Biotechnology Project (Regenomics, 2011-0007745) of the Korean Science and Engineering Foundation (KOSEF). Yu-Jin Kim was sponsored by the Ministry of Knowledge Economy (MKE) and Korea Industrial Technology Foundation (KOTEF) through the Human Resource Training Project for Strategic Technology
Copyright 2013 Elsevier B.V., All rights reserved.
- HT-29 human colorectal cancer cells
- Multicellular layer
- Multicellular spheroid
- Proliferation marker
- Three-dimensional culture
ASJC Scopus subject areas
- Molecular Medicine
- Drug Discovery
- Organic Chemistry