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Overexpression of the dynein light chain km23‐1 in human ovarian carcinoma cells inhibits tumor formation in vivo and causes mitotic delay at prometaphase/metaphase
Author(s) -
Pulipati Nageswara R.,
Jin Qunyan,
Liu Xin,
Sun Baodong,
Zhao Yan,
Pandey Manoj K.,
Huber Jonathan P.,
Ding Wei,
Mulder Kathleen M.
Publication year - 2011
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.25954
Subject(s) - prometaphase , metaphase , biology , mitosis , microbiology and biotechnology , ovarian carcinoma , mitotic index , cancer research , cell cycle , ovarian cancer , cell , anaphase , cancer , genetics , gene , chromosome
Abstract km23‐1 is a dynein light chain that was identified as a TGFβ receptor‐interacting protein. To investigate whether km23‐1 controls human ovarian carcinoma cell (HOCC) growth, we established a tet‐off inducible expression system in SKOV‐3 cells in which the expression of km23‐1 is induced upon doxycycline removal. We found that forced expression of km23‐1 inhibited both anchorage‐dependent and anchorage‐independent growth of SKOV‐3 cells. More importantly, induction of km23‐1 expression substantially reduced the tumorigenicity of SKOV‐3 cells in a xenograft model in vivo . Fluorescence‐activated cell sorting analysis of SKOV‐3 and IGROV‐1 HOCCs demonstrated that the cells were accumulating at G2/M. Phospho‐MEK, phospho‐ERK and cyclin B1 were elevated, as was the mitotic index, suggesting that km23‐1 suppresses HOCCs growth by inducing a mitotic delay. Immunofluorescence analyses demonstrated that the cells were accumulating at prometaphase/metaphase with increases in multipolar and multinucleated cells. Further, although the mitotic spindle assembly checkpoint protein BubR1 was present at the prometaphase kinetochore in Dox+/− cells, it was inappropriately retained at the metaphase kinetochore in Dox− cells. Thus, the mechanism by which high levels of km23‐1 suppress ovarian carcinoma growth in vitro and inhibit ovary tumor formation in vivo appears to involve a BubR1‐related mitotic delay.