Phenylbutyrate and Phenylacetate Induce Differentiation and Inhibit Proliferation of Human Medulloblastoma Cells

Abstract

Purpose: Phenylbutyrate (PB) and phenylacetate (PA) have antiproliferative and differentiation-inducing effects in malignant tumors, and had been evaluated in Phase I/II clinical trials. This study was undertaken to evaluate their antitumor activities in medulloblastomas.Experimental Design: The biological effects of PB and PA, ranging from 0.1 mM to 3 mM, on two medulloblastoma cell lines (DAOY and D283-MED) were examined using various long-term in vitro and in vivo assays for morphology, proliferation, differentiation, anchorageindependent growth, apoptosis, and tumorigenicity.Results: PB and PA can both induce morphological changes and suppress proliferation in a time-and dosedependent manner. These effects were more pronounced with PB and became irreversible in D283-MED cells after continuous exposure to 3 mM PB for 28 days. Both PB and PA were able to increase expression of glial marker glial fibriliary acidic protein and neuronal marker synaptophysin in two cell lines. For anchorage-independent growth, PB showed a more significant suppression than PA in D283-MED cells. PB caused more pronounced cell cycle arrest and remarkably reduced tumorigenicity in D283-MED cells than in DAOY cells. Apoptosis was readily induced in D283-MED cells with either low dose of PB or short-term treatment. In contrast, much higher concentrations of PB or longer treatment were required to achieve similar effect with DAOY cells. PB induced increased histones H3 acetylation in both cell lines, but histone H4 acetylation was only observed in D283-MED cells.Conclusions: PB, through induction of hyperacetylation of histone H3 and H4, is a much more potent antitumor agent than PA. 283-MED cells are more responsive to PB than DAOY cells, which may be dependent on their original state of differentiation as well as the changes of histone H4 acetylation status.

Complementary effects of HDAC inhibitor 4-PB on gap junction communication and cellular export mechanisms support restoration of chemosensitivity of PDAC cells

“…An induction of apoptosis upon 4-PB treatment is in agreement with studies showing this in cancer cell lines derived from other tumour entities like prostate cancer (Carducci et al, 1996), medulloblastoma (Li et al, 2004) or colon cancer (Feinman et al, 2002). Furthermore, in a rat model system 4-PB caused regression of tumours derived from hepatocarcinoma (Hep3B) or hepatoblastoma (HepT1) cells (Svechnikova et al, 2003).…”

“…like in stem cells) (Islam et al, 2005a, b), the decrease in cellular export caused by 4-PB might be due to induction of differentiation. This would be supported by other reports describing the potential of 4-PB to induce differentiation in tumour cells (Samid et al, 1997;Bar-Ner et al, 1999;Li et al, 2004). Thus, our findings that 4-PB increases the susceptibility of pancreatic carcinoma cells to apoptosis, that it increases intercellular communications and reduces cellular export makes 4-PB a promising drug for a combinatorial treatment with a 'classical' chemotherapeutical drug like gemcitabine or 5-FU, because higher differentiations grades are also associated with increased sensitivity to chemotherapy.…”

Histone deacetylase inhibitors induce cell death and enhance the susceptibility to ionizing radiation, etoposide, and TRAIL in medulloblastoma cells

“…However, the effects of these compounds on medulloblastoma have not been fully investigated. Recent studies have shown that the benzamide derivative, MS-275, inhibits DNA synthesis in DAOY and D283-Med medulloblastoma cells (23), and that the carboxylic acids, phenylbutyrate and phenylacetate, induce differentiation and inhibit proliferation in these cell lines in vitro and in vivo (24). Here, we demonstrate that the HDIs SAHA, NaB, and TSA were effective in inducing cell death in DAOY and UW228-2 medulloblastoma cells.…”

“…The clinical potential of these agents has been documented by several Phase I trials of different HDIs in patients with solid tumors or leukemias (12)(13)(14)(15)(16)(17). Various HDIs have been evaluated in brain tumors in a few studies (18)(19)(20)(21)(22) but, with the exception of MS-275 (23) and phenylbutyrate and phenylacetate (24), not in pediatric medulloblastoma.…”

Overexpression of Separase induces aneuploidy and mammary tumorigenesis

“…As a control, five mice were injected with empty vector clone (FSK3#64EV). Mice ages 6 -8 weeks were transplanted by s.c. injection of 5 ϫ 10 6 live cells into mammary gland, as described (28). Xenograft growth was measured weekly, and at the end of 1 month after injection, tumor-bearing mice were killed, and tumors specimens (1979, 1980, 1981, 1982, and 1983) were subjected to cytogenetic, histological, and Western blot analysis.…”