The microtubule-destabilizing protein stathmin is highly expressed in several types of

The microtubule-destabilizing protein stathmin is highly expressed in several types of tumor, thus deserving the name of oncoprotein 18. 3-methylcholanthrylene (3MC) treatments, respectively, we shown that knock-out of stathmin has no impact on the onset of malignancy in mice. No significant difference was noticed either when the Ras oncogene was mutated (pores and skin carcinogenesis model) or when the p53 pathway was inactivated (bladder carcinomas and fibrosarcomas). Finally, we concomitantly impinged on p53 and Ras pathways, by generating WT and stathmin KO mouse embryo fibroblasts transformed with papilloma computer virus large T antigen (LgTAg) plus the K-RasG12V oncogene. growth of xenografts from these transformed fibroblasts did not highlight any significant difference depending on the presence or absence of stathmin. Overall, our work demonstrates that stathmin manifestation is definitely dispensable for tumor onset, at least in mice, therefore making stathmin a virtually unique marker of aggressive disease and a encouraging therapeutic target for advanced cancers. Intro The phosphoprotein stathmin 1 (hereafter referred as stathmin) was initially identified as a cytosolic protein phosphorylated in response to several extracellular signals [1]. Further studies shown that stathmin is definitely a microtubule-destabilizing protein that is able to induce microtubules catastrophe [2] and to sequester free ?-tubulin heterodimers [3]. Stathmin N-terminal website consists of four serine residues (Ser16, Ser25, Ser38 and Ser63), KW-2478 which symbolize common phosphorylation focuses on of an expanding list of kinases, such as PI3K [4], [5], MAPK [6]C[9], PKA [10], [11], Calcium/Calmodulin kinase [12] and CDKs [10], [13]. Phosphorylation converts off the microtubule destabilizing activity of stathmin [14], is absolutely necessary for cells to enter mitosis, examined in [15] and modulates several fundamental cellular functions, such as cell motility, proliferation and apoptosis KW-2478 [16]C[22]. These observations are consistent with the name given to stathmin, deriving KW-2478 from your Greek term stathmos for relay to reflect its part as important intermediate of transmission transduction. Stathmin is definitely overexpressed in several types of tumor, therefore deserving its second name of oncoprotein 18 (OP18) [23]. Rabbit polyclonal to ZNF167. In human being cancers stathmin overexpression is definitely associated with improved malignancy, metastasis formation and decreased patient overall survival [16], suggesting that stathmin could serve as a molecular marker to identify patients with more aggressive disease. This notion is in accord with the ability of stathmin to activate cell motility and invasion and metastasis formation in several models of human being malignancy [4], [20], [24]C[28]. Besides, high levels of stathmin has also been linked, both and and methods shown that in p53-depedent carcinogenesis stathmin is definitely dispensable for tumor onset in mice. KW-2478 Its absence somehow rather slightly improved the appearance of bladder carcinomas in the BBN model, but this increment was not significant and did not correlate with gene dose, being present in both stathmin heterozygous and KO mice. Stathmin does not Affect Ras-driven Tumorigenesis We next asked whether stathmin manifestation could be necessary for tumor onset in a model of tumorigenesis driven from the Ras oncogene. To this aim, we used the Ras-dependent pores and skin carcinogenesis model, induced by treatment with 7,12-dimethylbenz[]antracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) [43]. It is already known that stathmin manifestation is definitely induced by DMBA treatment in mice [44] and also that stathmin is definitely a downstream target of the Ras-MAPK pathway, assisting the hypothesis that it could play a role with this mouse model of carcinogenesis. Since C57BL/6 mouse strain is usually highly resistant to DMBA/TPA-induced carcinogenesis [43], we used for this experimentation the FVB mouse strain. Tumors started to appear after 7C8 weeks of TPA treatment with no significant difference in tumor latency among 10 WT, 12 heterozygous and 9 stathmin KO mice (Physique 4A). All mice developed tumors within 20 weeks (Physique 4A). Stathmin heterozygous and KO mice developed a slightly higher number of tumor/mouse respect to the WT ones, but the difference did not reach statistical significance (Physique 4B). The pathological and immunohistochemical analyses using loricrin and cytokeratins (CK) 1 and 8 as markers of tumor progression [43] revealed that all analyzed tumors were papillomas (loricrin and CK1 positive but CK8 unfavorable) (Physique 4C). Thus, the absence of stathmin did not induce any change in the rate of papilloma-carcinoma conversion. Physique 4 Stathmin is not required for tumor onset following DMBA/TPA treatment in mice. Tumors from WT and stathmin KO mice were also analyzed for their proliferative index, using Ki67 as marker of cell proliferation. As shown in Physique 5, tumors from stathmin KO animals showed a slight increase in the percentage of Ki67 positive cells, when compared to those from WT animals. However, also in this case the difference did not reach statistical significance (p?=?0.06). Physique KW-2478 5 Analysis of tumor proliferation.