PROTEOMIC CHANGES INDUCED BY KNOCKDOWN OF STATHMIN IN BT549 BREAST CANCER CELL LINES
Breast cancer incidence in women in the United States is 1 in 8 (about 13%). In the U.S., breast cancer death rates are higher than any other cancer besides lung cancer, and more than 25% cancers are classified as breast cancer. In 2008, an estimated 182,460 new cases of invasive, along with 67,770 of non-invasive (in situ), breast cancers were diagnosed in women in the U.S. About 40,480 women in the U.S. were projected to die in 2008 from breast cancer.
Paclitaxel (Taxol), a microtubule (MT) stabilizing agent, was originally noted to be useful against breast cancers. Yet, like with many other cancer therapeutic agents, resistance to paclitaxel remains a significant problem in treating malignancies. One potential mechanism for the resistance observed is alterations in microtubule dynamics and altered binding of paclitaxel to its cellular target, the microtubule. Stathmin is a highly conserved, 17kDa protein that functions as an important regulator of microtubule dynamics. Several studies have shown potential correlations between stathmin levels and resistance to paclitaxel.
The latest results from our collaborator Prof. Mary Ann Jordan at the University of California-Santa Barbara clearly show that reduction of the level of stathmin in BT549 cells increases their sensitivity to paclitaxel (vide infra). This reduction must obviously result in some changes in the affected cells' proteome, which delivers a signal of regulatory importance to the MT system; The goal of the project was to detect and characterize the earliest proteomic changes, using 2-D DiGE and MALDI-TOF-MS, of BT549 breast cancer cell lines engineered with constitutively lowered stathmin levels. Two proteins, Protein Kinase C epsilon and Microtubule-Associate Protein 6, were identified to be expressed at lower levels with statistical significance, and potential mechanisms exit for those two proteins to interact with stathmin and/or microtubules are discussed. Based on this information, it is proposed that stathmin may play a role in certain integrating as well as diverse intracellular regulatory pathways. It is expected that this more detailed understanding of protein profile changes in these cells will allow for more rational decision-making in further research of the mechanisms leading to paclitaxel resistance.
Advisor:Billy W. Day; Charles Sfeir; Song Li; Regis R. Vollmer
School:University of Pittsburgh
School Location:USA - Pennsylvania
Source Type:Master's Thesis
Date of Publication:04/27/2009