Increases in NMR-visible lipid and glycerophosphocholine during phenylbutyrate-induced apoptosis in human prostate cancer cells.

DU145 human prostatic carcinoma cells were treated with the differentiating agents phenylacetate (PA) and phenylbutyrate (PB) and examined in perfused cultures by diffusion-weighted 1H and 31P nuclear magnetic resonance spectroscopy (NMR). PA and PB (10 mM) induced significant (>3-fold) time-dependent increases in the level of NMR-visible lipids and total choline in 1H spectra, and glycerophosphocholine levels in the 31P spectra, with the increases being greater for PB. These effects were accompanied by significant increases in cytoplasmic lipid droplets and intracellular lipid volume fraction as observed by morphometric analysis of Oil Red O-stained cells.

Capecitabine plus paclitaxel as front-line combination therapy for metastatic breast cancer: a multicenter phase II study.

Purpose: The goal of this multicenter, open-label phase II study was the clinical evaluation of combination therapy with the oral fluoropyrimidine capecitabine and the taxane paclitaxel in patients with metastatic breast cancer (MBC).

Patients And Methods: Forty-seven patients with MBC received oral capecitabine at 1650 mg/m(2)/d (825 mg/m(2) twice daily) on days 1 through 14, and intravenous infusion of paclitaxel at 175 mg/m(2) on day 1 of each 21-day treatment cycle. Treatment continued until disease progression, intolerable toxicity, or patient' s decision to discontinue.

Phase II study of capecitabine in patients with fluorouracil-resistant metastatic colorectal carcinoma.

Purpose: Capecitabine is an oral fluoropyrimidine converted to fluourouracil (FU) preferentially in tumor tissue. It has proven clinical activity against colorectal cancer when used as first-line therapy. The objectives of this study were to assess the safety and efficacy of capecitabine in patients with metastatic colorectal carcinoma who progressed despite previous FU therapy.

Inhibition of estrogen-dependent breast cell responses with phenylacetate.

The aromatic fatty acid phenylacetate (PA) and its analogs have come under intense investigation due to their ability to cause the growth arrest of a variety of neoplasia, including human breast cancer. We have determined that PA and its halide derivative 4-chlorophenylacetate (4-CPA) showed marked antiproliferative activity on 3 of 6 human breast cancer cell lines tested. Interestingly, the 3 cell lines that were growth inhibited by PA and 4-CPA were estrogen receptor (ER) positive (T47-D, MCF-7 and ZR-75-1) whereas those that were little affected by these compounds were ER-negative (MDA-MB-157, MDA-MB-231 and SK-Br-3).

Peroxisome proliferator-activated receptor gamma as a novel target in cancer therapy: binding and activation by an aromatic fatty acid with clinical antitumor activity.

Aromatic fatty acids, of which phenylacetate is a prototype, constitute a class of low toxicity drugs with demonstrated antitumor activity in experimental models and in humans. Using in vitro models, we show here a tight correlation between tumor growth arrest by phenylacetate and activation of peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear receptor superfamily. In support are the following observations: (a) the efficacy of phenylacetate as a cytostatic agent was correlated with pre-treatment levels of PPARgamma, as documented using established tumor lines and forced expression models; (b) in responsive tumor cells, PPARgamma expression was up-regulated within 2-9 h of treatment preceding increases in p21waf1, a marker of cell cycle arrest; (c) inhibition of mitogen-activated protein kinase, a negative regulator of PPARgamma, enhanced drug activity; and (d) phenylacetate interacted directly with the ligand-binding site of PPARgamma and activated its transcriptional function.

Phenylbutyrate-induced G1 arrest and apoptosis in myeloid leukemia cells: structure-function analysis.

The aromatic fatty acid phenylbutyrate (PB) induces cytostasis, differentiation, and apoptosis in primary myeloid leukemic cells at clinically achievable concentrations. In the present study, we have investigated the structural and cellular basis for PB-induced cytostasis, using the ML-1 human myeloid leukemia cell line as a model system. PB induced a dose-dependent increase in cells in G1 with a corresponding decrease in cells in S-phase of the cell cycle.

Phenylbutyrate induces cell differentiation and modulates Epstein-Barr virus gene expression in Burkitt's lymphoma cells.

Although Burkitt's lymphoma (BL) is a readily treated malignancy, recurrences, as well as disease arising in immunosuppressed patients, are notoriously resistant to conventional therapeutic approaches. The EBV is associated with a significant proportion of these lymphomas that evade immune surveillance through decreased expression of both viral and cellular antigens. Increasing the immunogenicity of BL cells may, therefore, represent a potentially beneficial therapeutic maneuver.

Impact of the putative differentiating agents sodium phenylbutyrate and sodium phenylacetate on proliferation, differentiation, and apoptosis of primary neoplastic myeloid cells.

Sodium phenylacetate (PA) and sodium phenylbutyrate (PB) are aromatic fatty acids that can effect differentiation in a variety of cell lines at doses that may be clinically attainable. We have studied the impact of these two agents on lineage- and differentiation stage-specific antigen expression, proliferation, apoptosis, and clonogenic cell survival in primary cultures of bone marrow samples from patients with myeloid neoplasms at presentation and in remission and from normal volunteers. PB inhibited the proliferation of primary acute myeloid leukemia cells in suspension culture with an ID50 of 6.

A phase II study of 5-aza-2'deoxycytidine (decitabine) in hormone independent metastatic (D2) prostate cancer.

Aims And Background: Decitabine (5-aza-2'-deoxycytidine) is an S-phase-specific pyrimidine analog with hypomethylation properties. In laboratory models of prostate cancer (PC-3 and DU-145), decitabine induces cellular differentiation and enhanced expression of genes involved in tumor suppression, immunogenicity, and programmed cell death.

Methods: We conducted a phase II study of decitabine in 14 men with progressive, metastatic prostate cancer recurrent after total androgen blockade and flutamide withdrawal.

Modulation of radiation response of human tumour cells by the differentiation inducers, phenylacetate and phenylbutyrate.

The aromatic fatty acids phenylacetate (PA) and phenylbutyrate (PB) are novel antitumour agents currently under clinical evaluation. Their ability to induce tumour differentiation in laboratory models and their low clinical toxicity profile makes them promising candidates for combination with conventional therapies. In the present studies, we characterized the interactions between these aromatic fatty acids and radiation, using as a model cell lines derived from cancers of the prostate, breast, brain and colon.

Phenylacetate and phenylbutyrate as novel, nontoxic differentiation inducers.

Phenylacetate and analogs represent a new class of pleiotropic growth regulators that alter tumor cell biology by affecting gene expression at both the transcriptional and post transcriptional levels. Based on these findings, NaPA and NaPB entered clinical trials at the National Cancer Institute. Ongoing phase I studies with NaPA, involving adults with prostate and brain cancer, have confirmed that therapeutic levels can be achieved with no significant toxicities, and provide preliminary evidence for benefit to patients with advanced disease (Thibault et al.

Up-regulation and functional role of p21Waf1/Cip1 during growth arrest of human breast carcinoma MCF-7 cells by phenylacetate.

Phenylacetate (PA) and related aromatic fatty acids constitute a novel class of relatively nontoxic antineoplastic agents. These compounds induce tumor cytostasis and growth inhibition and differentiation of cancer cells, but little is known regarding the molecular events mediating these biological effects. Using human breast carcinoma MCF-7 cells as a model, we show here that PA-induced growth arrest is associated with enhanced expression of the cyclin-dependent kinase inhibitor p21Waf1/Cip1 and dephosphorylation of the retinoblastoma protein (pRB).

Plasma protein binding of phenylacetate and phenylbutyrate, two novel antineoplastic agents.

Phenylacetate and phenylbutyrate, two novel inducers of tumor cytostasis and differentiation, are currently in clinical trials for the treatment of cancer in adults. The purpose of our study was to evaluate the plasma protein-binding characteristics of phenylacetate and phenylbutyrate in the plasma of normal volunteers and that of patients with cancer. Drug plasma protein-binding analysis was examined using three separate devices: a micropartition system and two equilibrium dialysis systems, all of which exhibited similar results.

Transcriptional upregulation of gamma-globin by phenylbutyrate and analogous aromatic fatty acids.

Phenylbutyrate has been shown recently to induce fetal hemoglobin (HbF) production in patients with sickle cell anemia and beta thalassemia. We have now examined related aromatic fatty acids in order to define the range of active structures and identify plausible mechanisms of action. Structure-function analysis revealed that for effective stimulation of HbF in erythroid precursors: (1) the ideal length for the aliphatic side chain is four carbons; (2) oxygen or sulfur substitutions in the carboxylic chain are allowed, as evidenced by the equal or increased activity of phenoxypropionate, benzylthioglycolate, and benzyloxyacetate compared with phenylbutyrate; and (3) blocking the carboxylate group by conversion to the amide form greatly reduces potency.

The differentiating agent phenylacetate increases prostate-specific antigen production by prostate cancer cells.

The prostatic-specific antigen (PSA) is the tumor marker most widely relied upon for the monitoring of patients with prostate cancer. Recently, declines in the serum concentrations of PSA have been advocated as a surrogate marker of tumor response in clinical trials of investigational antitumor agents. We examined the hypothesis that this postulate may not apply to the evaluation of drugs such as phenylacetate, a differentiating agent endowed with mechanisms of action different from those of classic cytotoxic chemotherapy.

Activation of a human peroxisome proliferator-activated receptor by the antitumor agent phenylacetate and its analogs.

The aromatic fatty acid phenylacetate and its analogs induce tumor cytostasis and differentiation in experimental models. Although the underlying mechanisms of action are not clear, effects on lipid metabolism are evident. We have now examined whether these compounds, structurally similar to the peroxisome proliferator clofibrate, affect the human peroxisome proliferator-activated receptor (hPPAR), a homolog of the rodent PPAR alpha, a transcriptional factor regulating lipid metabolism and cell growth.

Phenylacetate inhibits protein isoprenylation and growth of the androgen-independent LNCaP prostate cancer cells transfected with the T24 Ha-ras oncogene.

The refractoriness of prostate cancer to androgen suppression is the landmark of clinically aggressive disease. In this study, the androgen-dependent LNCaP prostate cancer cells were transfected with the mutated c-Ha-ras gene from the T24 human bladder cancer. The derivative clone overexpressing T24-ras (LNCaP(T24-ras)) proliferated in androgen-depleted medium and showed increased growth.

Vulnerability of multidrug-resistant tumor cells to the aromatic fatty acids phenylacetate and phenylbutyrate.

Cytotoxic chemotherapies often give rise to multidrug resistance, which remains a major problem in cancer management. In pursuit of alternative treatments for chemoresistant tumor cells, we tested the response of multidrug-resistant (MDR) tumor cell lines to the aromatic fatty acids phenylacetate (PA) and phenylbutyrate (PB), two differentiation inducers currently in clinical trials. Both compounds induced cytostasis and maturation of multidrug-resistant breast, ovarian, and colon carcinoma cells with no significant effect on cell viability.

Phenylacetate is an inhibitor of prostatic growth and development in organ culture.

Purpose: Benign prostatic hyperplasia (BPH) is the most common proliferative disease affecting men, and the obstructive uropathy it causes results in serious morbidity and financial cost. Phenylacetate (PA) is a small molecule that is a product of phenylalanine metabolism and is normally present in the mammalian circulation at very low levels. It has long been safely used in humans to treat the hyperammonemia resulting from urea synthesis disorders and liver failure.

Phase I study of lovastatin, an inhibitor of the mevalonate pathway, in patients with cancer.

Lovastatin, an inhibitor of the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (the major regulatory enzyme of the mevalonate pathway of cholesterol synthesis), displays antitumor activity in experimental models. We therefore conducted a Phase I trial to characterize the tolerability of lovastatin administered at progressively higher doses to cancer patients. From January 1992 to July 1994, 88 patients with solid tumors (median age, 57 +/- 14 years) were treated p.

Lipid metabolism as a target for brain cancer therapy: synergistic activity of lovastatin and sodium phenylacetate against human glioma cells.

Malignant gliomas, the most common form of primary brain tumors, are highly dependent on the mevalonate (MVA) pathway for the synthesis of lipid moieties critical to cell replication. Human glioblastoma cells were found to be uniquely vulnerable to growth arrest by lovastatin, a competitive inhibitor of the enzyme regulating MVA synthesis, 3-hydroxy-3-methylglutaryl coenzyme A reductase. The sodium salt of phenylacetic acid (NaPA), an inhibitor of MVA-pyrophosphate decarboxylase, the enzyme that controls MVA use, acted synergistically with lovastatin to suppress malignant growth.

Functional analysis of the promoter and first intron of the human lysyl oxidase gene.

Alterations in the synthesis and activity of lysyl oxidase occur concomitant with developmental changes in collagen and elastin deposition and with the pathogenesis of several acquired and heritable connective tissue disorders. To begin to unravel the mechanisms that control lysyloxidase gene expression, we have previously reported the complete exon-intron structure of the human lysyl oxidase gene. We have now sequenced this entire gene, including all six introns and 4 kb of DNA 5' of exon 1.

Transcriptional activation of the Epstein-Barr virus latency C promoter after 5-azacytidine treatment: evidence that demethylation at a single CpG site is crucial.

The Epstein-Barr Virus (EBV) latency C promoter (Cp) is the origin of transcripts for six viral proteins. The promoter is active in lymphoblastoid B-cell lines but silent in many EBV-associated tumors and tumor cell lines. In these latter cell lines, the viral episome is hypermethylated in the vicinity of this promoter.