The use of protein BioMarkers for identifying and analyzing primary tumors and metastasis is gaining credibility in both the research and clinical arenas. Expression patterns in normal compared to tumor cells may include up- or down-regulation of different proteins as well as post-translational modifications like increased phosphorylation. For example, S100A7/HID5/Psoriasin is a putative Breast cancer BioMarker because it is up-regulated in Ductal Carcinoma in situ relative to normal or invasive cancerous breast tissue. Analogously, up-regulation of Phosphorylated Androgen Receptor (Ser213/210) (IMG-561) has been associated with prostate cancer, and is a putative BioMarker target for chemotherapeutic intervention.

Intimately related to tumors is the cellular environment in which they co-exist. It is likely that protein BioMarkers will become increasingly useful tools for elucidating the interplay between tumor cells and their microenviroment. Recently putative inflammatory BioMarkers of the “tumor microenvironment” have gained recognition for elucidating the biology of cancer, and may provide additional diagnostic, monitoring and therapeutic opportunities. For example, DeltaRb-p70, a novel form of the retinoblastoma protein, has been shown to be associated with tumor-associated macrophages (TAMs) in primary human breast tumors but not the tumor cells themselves.

Additionally, the inflammatory Caspase-1 (IMG-5028) is present in a subset of colon carcinoma cases, and localized to the TAMs in others. Caspase-1 also localizes to the macrophages of reactive lymph node (IMG-5025). These results suggest that Caspase-1 may be a BioMarker of a subset of colon cancers, whereas it may be a TAM BioMarker in others