Coordinated Expression of Stathmin Family Members by Far Upstream Sequence Element-Binding Protein-1 Increases Motility in Non-Small Cell Lung Cancer

S. Singer, M. Malz, E. Herpel, A. Warth, M. Bissinger, M. Keith, T. Muley, M. Meister, H. Hoffmann, R. Penzel, G. Gdynia, V. Ehemann (+5 others)
2009 Cancer Research  
Dynamic instability of the microtubule network modulates processes such as cell division and motility, as well as cellular morphology. Overexpression of the microtubule-destabilizing phosphoprotein stathmin is frequent in human malignancies and represents a promising therapeutic target. Although stathmin inhibition gives rise to antineoplastic effects, additional and functionally redundant microtubule-interacting proteins may attenuate the efficiency of this therapeutic approach. We have
more » ... ach. We have systematically analyzed the expression and potential protumorigenic effects of stathmin family members in human non-small cell lung cancer (NSCLC). Both stathmin and stathmin-like 3 (SCLIP) were overexpressed in adenocarcinoma as well as squamous cell carcinoma (SCC) tissues and induced tumor cell proliferation, migration, and matrix invasion in respective cell lines. Accordingly, reduced stathmin and SCLIP levels affected cell morphology and were associated with a less malignant phenotype. Combined inhibition of both factors caused additive effects on tumor cell motility, indicating partial functional redundancy. Because stathmin and SCLIP expression significantly correlated in NSCLC tissues, we searched for common upstream regulators and identified the far upstream sequence element-binding protein-1 (FBP-1) as a pivotal inducer of several stathmin family members. Our results indicate that the coordinated overexpression of microtubule-destabilizing factors by FBP-1 is a critical step to facilitate microtubule dynamics and subsequently increases proliferation and motility of tumor cells. transient transfection of three independent gene-specific siRNA as compared with appropriate controls. B, reduction of stathmin and SCLIP expression as well as combined inhibition of both targets in Calu-6 cells at the protein level after transfection of three independent gene-specific siRNA. For further functional studies, siRNA no. 1 and siRNA no. 2 (alone and in combination) were used. The effects of efficient inhibition on tumor cell viability in Calu-1 cells after stathmin knockdown (C ) and Calu-6 cells after single as well as combined gene inhibition of stathmin and SCLIP (D ) were analyzed by MTT assays. The effect on Calu-1 proliferation after stathmin reduction (C) and Calu-6 cells after single as well as combined gene inhibition of stathmin and SCLIP (D) was examined by bromodeoxyuridine ELISA. Figure 4. Stathmin and SCLIP induce NSCLC cell migration and invasion. The effects on tumor cell migration of Calu-1 cells after stathmin inhibition (A) and Calu-6 cells after single as well as combined gene knockdown of stathmin and SCLIP (B) were analyzed using a two-dimensional scratch assay. Representative areas are shown for experimental conditions. The effects on tumor cell invasion of Calu-1 cells after stathmin reduction (C) and Calu-6 cells after single as well as combined gene inhibition of stathmin and SCLIP (D ) were examined using three-dimensional matrix invasion assays. Representative spheroids are shown for all conditions. # , value used for statistical calculation, single gene inhibition vs. combined inhibition (combi-1 ).
doi:10.1158/0008-5472.can-08-3338 pmid:19258502 fatcat:dms6ifvqwfeylku5ymeisgv5uy