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ras oncoproteins and ras-related proteins constitute a large family of the small GTP-binding protein family. The rab branch of the ras superfamily is involved in the intracellular transport along the secretory and endocytic pathway in eukaryotic cells. We here demonstrate that a member of the rab branch, the rab2 protein, is frequently overexpressed in peripheral blood mononuclear cells from patients with solid neoplasms. Moreover, this expression is shown to be greatly modified during the course of therapy. Our results provide strong evidence for the implication of a small GTP-binding protein in immunological events associated with neoplastic diseases. The precise cellular population involved as well as the potential prognostic value of this process remains to be determined.

Immunosuppressive acidic protein (IAP) is a non-specific immunoreactive protein arising from inflammatory or malignant conditions in the human body. We determined the IAP levels in 65 cases with urological malignancies and in 31 cases with benign diseases as a control group during a 9-month period. There were significantly higher serum levels of IAP in cases of bladder transitional cell carcinoma (p = 0.025), prostate adenocarcinoma (p less than 0.00001) and upper urinary tract urothelial cancer (kidney and/or ureter, p = 0.013) as compared with those of the control group. Significant differences in IAP between different tumor stages were found in the bladder cancer group with high stage cases having higher IAP levels (p less than 0.0005). However, no significant differences were found between different tumor gradings. Most of the prostate cancer patients had extremely high IAP values (1,029 +/- 490 micrograms/ml) in this study. Renal cell carcinoma and testicular tumors showed no statistical differences from the control group (p = 0.89 and 0.37, respectively). No differences could be found in the different age groups (by decades) or sexes. The serum IAP level can be a good non-specific tumor marker for bladder cancer staging and probably a good follow-up tool for most urological malignancy patients.

It was previously shown (Am J Clin Pathol 55: 65-67, 1971) that sera from patients with chronic lymphocytic leukemia (CLL) produce a characteristic pattern on disk-acrylamide gels. Other observations indicating the presence of immunosuppressive proteins in the sera of patients with cancer suggested the search for characteristic protein patterns employing the same technic. Utilizing sera from patients with various types of malignancies and appropriate controls, the results appear to indicate that there is a consistent and distinctive pattern to the gels. The nature of the (different) protein(s) remains to be elucidated.