Doxorubicin is considered to be the most effective agent in the treatment of breast cancer patients. Unfortunately, resistance to this agent is common, representing a major obstacle to successful treatment. The identification of novel biomarkers that are able to predict treatment response may allow therapy to be tailored to individual patients. Antibody microarrays provide a powerful new technique, enabling the global comparative analysis of many proteins simultaneously. This technology may identify a panel of proteins to discriminate between drug-resistant and drug-sensitive samples. The Panorama Cell Signaling Antibody Microarray was exploited to analyze the MDA-MB-231 breast cancer cell line and a novel derivative, which displays significant resistance to doxorubicin at clinically relevant concentrations. The microarray comprised 224 antibodies selected from a variety of pathways, including apoptotic and cell signaling pathways. A standard z2.0-fold cutoff value was used to determine differentially expressed proteins. A decrease in the expression of mitogen-activated protein kinaseactivated monophosphotyrosine (phosphorylated extracellular signal-regulated kinase; 2.8-fold decrease), cyclin D2 (2.5-fold decrease), cytokeratin 18 (2.5-fold decrease), cyclin B1 (2.4-fold decrease), and heterogeneous nuclear ribonucleoprotein m3-m4 (2.0-fold decrease) was associated with doxorubicin resistance. Western blotting was exploited to confirm results from the antibody microarray experiment. These results suggest that antibody microarrays can be used to identify novel biomarkers and further validation may reveal mechanisms of chemotherapy resistance and identify potential therapeutic targets.

Calmodulin is an essential regulator of intracellular processes in response to extracellular stimuli mediated by a rise in Ca 2؉ ion concentration. To profile protein-protein interactions of calmodulin in human brain, we probed a high content human protein array with fluorophore-labeled calmodulin in the presence of Ca

Little is known about the Bcl-2 family members in mesothelioma. These proteins are involved in the control of apoptosis, carrying out both pro- and anti- apoptotic functions. Immunohistochemistry was used to examine the expression of p53 and Bcl-2 family members in 54 archival mesothelioma samples (39 epithelial, 15 sarcomatoid tumours). Overexpression of p53 was observed in 81% (44/54). For anti-apoptotic proteins, overexpression was recorded as follows: Bcl-2 40% (22/54), Bcl-XL 24% (13/54), Mcl-1 92% (50/54). For pro-apoptotic proteins, loss of expression was recorded as follows: Bad 25% (14/54), Bak 24% (13/54), Bax 42% (23/54), Bid 37% (20/54), Bim 18% (10/54). Statistically significant differences between epithelial and sarcomatoid tumours were observed for Bid (p < 0.001), Bad (p = 0.012) and Bcl-XL (p = 0.03). Significant differences in abnormal expression of apoptosis proteins were found between epithelial and sarcomatoid subtypes but histological subtype was the only factor with significant association to patient prognosis.