Diane George

Proteomic Analysis of Waldenstrom Macroglobulinemia

To better understand the molecular changes that occur in Waldenstrom macroglobulinemia (WM), we employed antibody-based protein microarrays to compare patterns of protein expression between untreated WM and normal bone marrow controls. Protein expression was defined as a >2-fold or 1.3-fold change in at least 67% of the tumor samples. Proteins up-regulated by >2-fold included Ras family proteins, such as Rab-4 and p62DOK, and Rho family proteins, such as CDC42GAP and ROKalpha. Other proteins up-regulated by >1.3-fold included cyclin-dependent kinases, apoptosis regulators, and histone deacetylases (HDAC). We then compared the samples of patients with symptomatic and asymptomatic WM and showed similar protein expression signatures, indicating that the dysregulation of signaling pathways occurs early in the disease course. Three proteins were different by >2-fold in symptomatic versus asymptomatic, including the heat shock protein HSP90. Elevated protein expression was confirmed by immunohistochemistry and immunoblotting. Functional significance was validated by the induction of apoptosis and inhibition of proliferation using specific HDAC and HSP90 inhibitors. This study, therefore, identifies, for the first time, multiple novel proteins that are dysregulated in WM, which both enhance our understanding of disease pathogenesis and represent targets of novel therapeutics.

Clinical and pathological prognostic markers for survival in adult patients with post-transplant lymphoproliferative disorders in solid transplant.

We sought to determine the clinical and immunohistopathological prognostic factors for overall survival (OS) in adult patients with post-transplant lymphoproliferative disorders (PTLDs). Eighty-four patients diagnosed with PTLDs between 1980 and 2004 at the University of Pittsburgh Medical Center were identified. Immunohistochemical staining was performed on tumor tissue at the time of diagnosis for the following proteins: Bcl-2, Bcl-6, c-myc and p53. The median survival for all patients was 20.8 months, 95% CI: (7.4–77.6). On univariate analysis for OS, the following poor prognostic factors were identified: age at transplant >60 years (p = 0.024), multiorgan transplant (p = 0.019), ECOG > 2 (p < 0.0001), grafted organ involvement (p < 0.0001), extranodal disease (p = 0.011), early (<1 year) PTLDs (p < 0.0001), stage IV (p = 0.0017), EBV positive (p = 0.012) and elevated white blood count (p = 0.010). Good prognostic factors included ECOG<2 (p < 0.0001), late (>1 year) PTLDs (p = 0.002), early stage at diagnosis (stages I and II, p = 0.005), nodal disease (p = 0.0053), monomorphic disease (0.0034), initial immunosuppression reduction (p = 0.0015) and use of rituximab (p = 0.045). Bcl-2 but not Bcl-6, c-myc, or p53 correlated with poor survival, p = 0.0036. This study identifies new clinical and pathological markers for poor survival in PTLDs.

Proteomics analysis in post‐transplant lymphoproliferative disorders

Little is known about the biology of post‐transplant lymphoproliferative disorders (PTLDs). The objective of this study was to determine the molecular alterations that occur at the protein level in patients with PTLDs. Six tumor samples from adult patients with PTLD and four benign lymph nodes were studied using protein microrarray technique. Proteins that were dysregulated included proteins in the PI3K/mTOR, NFkB and HSP90 pathways. Inhibitors of these proteins induced cytotoxicity and apoptosis in EBV+ve and –ve cell lines. These results provide insight into pathways that are dysregulated in PTLD and can be targeted in future clinical trials.