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The natural tetrapeptide acetyl-ser-asp-lys-pro (AcSDKP) is formed in vivo by enzymatic cleavage of the N terminus of thymosin beta4 by prolyl oligopeptidase (POP). Recently, AcSDKP was shown to promote angiogenesis. Because of the critical role of neovascularization in cancer development, the levels of AcSDKP and POP activity in a number of different malignant tissues were investigated. Our studies revealed that AcSDKP levels were markedly elevated in neoplastic diseases including hematologic malignancies and solid neoplasms. Consistent with this finding, the enhanced activity of POP was also detected in all analyzed specimens of cancer tissues. Both these novel findings are in concert with the previously reported overexpression of thymosin beta4 in a large variety of malignant tumors and with its potential role in cancerogenesis. The physiological relevance of these findings awaits further studies; however, our first results strongly suggest a key role for AcSDKP in the pathogenesis of cancer.

Background: The putative pharmacophore of a naturally cytotoxic limonoid haperforin B1, E-5-iodomethylene-6,6-dimethyl-5,6-dihydropyran-2-one (IDDP) was synthesized and its biological activity was investigated., Materials and Methods: The cytotoxicity of IDDP was assessed using human breast, lung, colorectal and epidermal carcinomas, chronic myeloid leukemia and glioblastoma cell lines. Cell cycle analysis was performed by flow cytometry. The induction of apoptosis was studied by a caspase assay and by annexin V-propidium iodide double staining. The organization of actin and tubulin microfilaments was analysed by immunocytochemical labeling., Results: IDDP was shown to inhibit the growth of a panel of human cancer cell lines independently of their p53 status with IC(50) ranging from 0.07 to 0.50 microM. All the treated cells were arrested in the G(2)/M phase in a time-dependent manner before cell death occurred through an apoptotic pathway. Immunocytochemical studies revealed that the normal organization of microfilaments and microtubules was disrupted in IDDP exposed cells., Conclusion: IDDP can be considered as a promising anticancer agent.

Background: The natural tetrapeptide acetyl-Ser-Asp-Lys-Pro (AcSDKP), generated from thymosin beta4 following its cleavage by prolyl oligopeptidase (POP), is a physiological stimulator of angiogenesis. Because of the critical role of neovascularisation in tumor development, the expression of AcSDKP and the activity of POP were examined in different human solid malignancies., Materials and Methods: The expression of AcSDKP and the activity of POP were evaluated in human blood samples and tissue specimens of thyroid goiter and thyroid papillary carcinoma as well as in commercial cancer tissue microarray., Results: A significantly increased concentration of AcSDKP in intratumoral blood and enhanced tissular activity of POP were detected in cancer patients. The expression of AcSDKP in human breast, colon, head and neck, kidney, lung, skin, ovary and prostate cancer tissues was shown to be greater than that in normal tissues., Conclusion: AcSDKP and POP contribute to the malignant phenotype and these molecules are potentiel markers of cancer.