title: Non-nuclear localization of Ki-67 in human colorectal cancer cells grown as multicellular layers.
abstract: 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.
authors.affiliation: Department of Biomedical Sciences, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul, 137-701, South Korea.
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Jaehwi
authors.initials: J
authors.lastname: Lee
authors.forename: Hyo-Jeong
authors.initials: HJ
authors.lastname: Kuh
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D018929:Cell Culture Techniques; D002453:Cell Cycle / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D015179:Colorectal Neoplasms / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004317:Doxorubicin / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D019073:HT29 Cells; D006801:Humans; D019394:Ki-67 Antigen / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D017239:Paclitaxel / Q000493:pharmacokinetics / Q000494:pharmacology; D018874:Spheroids, Cellular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D004317:Doxorubicin; D017239:Paclitaxel