title: Overexpression of centrosomal protein Nlp confers breast carcinoma resistance to paclitaxel.
abstract: Nlp (ninein-like protein), an important molecule involved in centrosome maturation and spindle formation, plays an important role in tumorigenesis and its abnormal expression was recently observed in human breast and lung cancers. In this study, the correlation between overexpression of Nlp and paclitaxel chemosensitivity was investigated to explore the mechanisms of resistance to paclitaxel and to understand the effect of Nlp upon apoptosis induced by chemotherapeutic agents. Nlp expression vector was stably transfected into breast cancer MCF-7 cells. With Nlp overexpression, the survival rates, cell cycle distributions and apoptosis were analyzed in transfected MCF-7 cells by MTT test and FCM approach. The immunofluorescent assay was employed to detect the changes of microtubule after paclitaxel treatment. Immunoblotting analysis was used to examine expression of centrosomal proteins and apoptosis associated proteins. Subsequently, Nlp expression was retrospectively examined with 55 breast cancer samples derived from paclitaxel treated patients. Interestingly, the survival rates of MCF-7 cells with Nlp overexpressing were higher than that of control after paclitaxel treatment. Nlp overexpression promoted G2-M arrest and attenuated apoptosis induced by paclitaxel, which was coupled with elevated Bcl-2 protein. Nlp expression significantly lessened the microtubule polymerization and bundling elicited by paclitaxel attributing to alteration on the structure or dynamics of β-tubulin but not on its expression. The breast cancer patients with high expression of Nlp were likely resistant to the treatment of paclitaxel, as the response rate in Nlp negative patients was 62.5%, whereas was 58.3 and 15.8% in Nlp (+) and Nlp (++) patients respectively (p = 0.015). Nlp expression was positive correlated with those of Plk1 and PCNA. These findings provide insights into more rational chemotherapeutic regimens in clinical practice, and more effective approaches might be developed through targeting Nlp to increase chemotherapeutic sensitivity.
authors.affiliation: Department of Medical Oncology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Weihong
authors.initials: W
authors.lastname: Zhao
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Song
authors.forename: Binghe
authors.initials: B
authors.lastname: Xu
authors.forename: Qimin
authors.initials: Q
authors.lastname: Zhan
mesh_terms: D000328:Adult; D000368:Aged; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival; D019008:Drug Resistance, Neoplasm; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology* / Q000627:therapeutic use; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D055815:Young Adult; D000097869:Polo-Like Kinase 1
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D017239:Paclitaxel; D018809:Proliferating Cell Nuclear Antigen; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1; C476755:NINL protein, human