Date of Award

Winter 2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program/Concentration

Biomedical Sciences

Committee Director

O. John Semmes

Committee Member

Richard R. Drake

Committee Member

Julie A. Kerry

Committee Member

Ann E. Campbell

Abstract

The elucidation of new biological markers of prostate cancer (PCa) should aid in the detection, and prognosis of this disease. Diagnostic decision making by pathologists in prostate cancer is highly dependent on tissue morphology. The ability to localize disease-specific molecular changes in tissue would help improve this critical pathology decision making process. Direct profiling of proteins in tissue sections using MALDI imaging mass spectrometry (MALDI-IMS) has the power to link molecular detail to morphological and pathological changes, enhancing the ability to identify candidates for new specific biomarkers. However, critical questions remain regarding the integration of this technique with clinical decision making. To address these questions, and to investigate the potential of MALDI-IMS for the diagnosis of prostate cancer, we have used this approach to analyze prostate tissue for the determination of the cellular origins of different protein signals to improve cancer detection and to identify specific protein markers of PCa. We found that specific protein/peptide expression changes correlated with the presence or absence of prostate cancer as well as the presence of micro-metastatic disease. Additionally, the over-expression of a single peptide (m/z = 4355) was able to accurately define primary cancer tissue from adjacent normal tissue. Tandem mass spectrometry analysis identified this peptide as a fragment of MEKK2, a member of the MAP kinase signaling pathway. Validation of MEKK2 overexpression in moderately differentiated PCa and prostate cancer cell lines was performed using immunohistochemistry and Western Blot analysis. Classification algorithms using specific ions differentially expressed in PCa tissue and a ROC cut-off value for the normalized intensity of the MEKK2 fragment at m/z 4355 were used to classify a blinded validation set. Finally, the optimization of sample processing in a new fixative which preserves macromolecules has led to improved through-put of samples making MALDI-IMS more compatible with current histological applications, facilitating its implementation in a clinical setting. This study highlights the potential of MALDI-IMS to define the molecular events involved in prostate tumorigenesis and demonstrates the applicability of this approach to clinical diagnostics as an aid to pathological decision making in prostate cancer.

Comments

Dissertation submitted to the Faculty of Eastern Virginia Medical School and Old Dominion University in Partial Fulfillment of the Requirement for the Degree of Doctor of Philosophy in Biomedical Sciences.

DOI

10.25777/3wv0-w128

ISBN

9781109079388

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