Progression to androgen independence remains the main problem that impacts on survival and quality of life in prostate cancer patients. We have investigated the potency of tributyrin, an orally available prodrug of butyrate, to induce growth arrest, differentiation and apoptosis in LNCaP, PC-3 and TSU-PR1 human prostate cancer cell lines. Cells were treated with 0.1 to 5 mM tributyrin or sodium butyrate. Growth inhibition, cell cycle arrest and apoptosis induction was assessed using standard methods. Both agents induced a more differentiated, fibroblast-like phenotype in androgen-sensitive as well as androgen-resistant cell lines. Expression of prostate-specific antigen was increased in LNCaP cells by tributyrin as a indicator of differentiation. The IC(50) for sodium butyrate was 2.5 mM in PC-3 and TSU-PR1 cells. LNCaP cells exhibited <50% growth inhibition at 5 mM sodium butyrate. However, the IC(50) for tributyrin was 0.8 mM in PC-3 cells, 1.2 mM in TSU-PR1 cells and 3.1 mM in LNCaP cells. Flow cytometry revealed a strong G1-arrest after exposure to tributyrin or sodium butyrate. Both agents resulted in a strong increase of apoptosis rates compared with mock-treated cells. Overall, tributyrin had a 2.5- to 3-fold growth inhibitory and apoptosis-inducing potency compared with equimolar concentrations of sodium butyrate. Our results demonstrate that tributyrin is more potent than butyrate in regard to cell growth inhibition and apoptosis induction at pharmacologically relevant concentrations. Hence, tributyrin may be a promising candidate for clinical protocols in prostate cancer.

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Progression to androgen independence remains the main problem that impacts on survival and quality of life in prostate cancer patients. We have investigated the potency of tributyrin, an orally available prodrug of butyrate, to induce growth arrest, differentiation and apoptosis in LNCaP, PC‐3 and TSU‐PR1 human prostate cancer cell lines. Cells were treated with 0.1 to 5 mM tributyrin or sodium butyrate. Growth inhibition, cell cycle arrest and apoptosis induction was assessed using standard methods. Both agents induced a more differentiated, fibroblast‐like phenotype in androgen‐sensitive as well as androgen‐resistant cell lines. Expression of prostate‐specific antigen was increased in LNCaP cells by tributyrin as a indicator of differentiation. The IC50 for sodium butyrate was 2.5 mM in PC‐3 and TSU‐PR1 cells. LNCaP cells exhibited <50% growth inhibition at 5 mM sodium butyrate. However, the IC50 for tributyrin was 0.8 mM in PC‐3 cells, 1.2 mM in TSU‐PR1 cells and 3.1 mM in LNCaP cells. Flow cytometry revealed a strong G1‐arrest after exposure to tributyrin or sodium butyrate. Both agents resulted in a strong increase of apoptosis rates compared with mock‐treated cells. Overall, tributyrin had a 2.5‐ to 3‐fold growth inhibitory and apoptosis‐inducing potency compared with equimolar concentrations of sodium butyrate. Our results demonstrate that tributyrin is more potent than butyrate in regard to cell growth inhibition and apoptosis induction at pharmacologically relevant concentrations. Hence, tributyrin may be a promising candidate for clinical protocols in prostate cancer. Int. J. Cancer 88:245–251, 2000. © 2000 Wiley‐Liss, Inc.

In the present investigation we have sought for atrial natriuretic peptide (ANP)-like immunoreactivity in aorta, carotid artery, cultured aortic cells and cultured cardiac myocytes of the rat at the light-and electron-microscopic level using antibodies directed against atriopeptin II (5-27).Aortic and carotid aretery sections as well as cultured aortic cells did not show any ANP-specific immunoreactivity, preabsorbable by atriopeptin II or a-rat ANP (1-28).Cultured cardiac myocytes could be shown to contain ANP granules and secrete immunoreactive ANP.

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