The inhibitory effect of diarylpropionitrile,a selective agonist of estrogen receptor beta,on the growth of MC38 colon cancer line

The protective role of estrogens in the colon carcinogenesis has been suggested for many years and attributed mainly to estrogen receptor beta (ERβ). However, the direct effect of estrogens and their action through ERβ on the growth of colon cancer have been rarely studied.     

CYP1B1 gene polymorphisms have higher risk for endometrial cancer,and positive correlations with estrogen receptor alpha and estrogen receptor beta expressions

The estradiol metabolites by CYP1B1 received particular attention because of their causative role in malignant transformation of endometrium. We hypothesize that polymorphisms of CYP1B1 gene can predict higher incidence of endometrial cancer. To test this hypothesis, the genetic distributions of six different CYP1B1 gene polymorphisms were investigated, by sequence-specific PCR and direct DNA sequencing, in 113 Japanese endometrial cancer patients and 202 healthy controls. We also investigated whether the expression of estrogen receptors (ERalpha and ERbeta), progesterone receptor, and androgen receptor genes are influenced by the CYP1B1 genotypes in endometrial cancer. The results of our study demonstrated that the distributions of CYP1B1 genotypes at codons 119 and 432 were significantly different between endometrial cancer patients and healthy normal controls. The relative risks of 119T/T and 432G/G in endometrial cancer were calculated as 3.32 and 2.49 compared with wild-types. The 119T/T showed significant correlation for positivities of ERalpha and ERbeta. The 432G/G also showed weak correlations for ERalpha positivity. Other loci, intron 1, codon 48, and codon 449 were not different between endometrial cancer patients and healthy normal control. This is the first report that demonstrates that the rare polymorphisms at codons 119 and 432 of CYP1B1 gene have higher risk for endometrial cancer, and positive correlations with ERalpha and ERbeta expressions in endometrial cancer.     

Inhibition of angiogenesis and tumor growth by SCH221153, a dual alpha(v)beta3 and alpha(v)beta5 integrin receptor antagonist

New blood vessel formation is essential for tumor growth and metastatic spread. Integrins alpha(v)beta3 and alpha(v)beta5 are arginine-glycine-aspartic acid-dependent adhesion receptors that play a critical role in angiogenesis. Hence, selective dual alpha(v)beta3 and alpha(v)beta5 antagonists may represent a novel class of angiogenesis and tumor-growth inhibitors. Here, an arginine-glycine-aspartic acid-based peptidomimetic library was screened to identify alpha(v)beta3 antagonists. Selected compounds were then modified to generate potent and selective dual inhibitors of alpha(v)beta3 and alpha(v)beta5 receptors. One of these compounds, SCH 221153, inhibited the binding of echistatin to alpha(v)beta3 (IC50 = 3.2 nM) and alpha(v)beta5 (IC50 = 1.7 nM) with similar potency. Its IC50 values for related alpha(IIb)beta3 and alpha5beta1 receptors were 1294 nM and 421 nM, respectively, indicating that SCH 221153 is highly selective for alpha(v)beta3 and alpha(v)beta5 receptors. In cell-based assays, SCH 221153 inhibited the binding of echistatin to alpha(v)beta3- and alpha(v)beta5-expressing 293 cells and blocked the adhesion of endothelial cells to immobilized vitronectin and fibroblast growth factor 2 (FGF2). SCH 221153, but not the inactive analogue SCH 216687, was effective in inhibiting FGF2 and vascular endothelial growth factor-induced endothelial cell proliferation in vitro with an IC50 equal to 3-10 microM. Angiogenesis induced by FGF2 in the chick chorioallantoic membrane assay was also inhibited by SCH 221153. Finally, SCH 221153 exerted a significant inhibition on tumor growth induced by intradermal or s.c. injection of human melanoma LOX cells in severe combined immunodeficient mice.     

Assessment of the biological and pharmacological effects of the alpha nu beta3 and alpha nu beta5 integrin receptor antagonist, cilengitide (EMD 121974), in patients with advanced solid tumors.

BACKGROUND: Cilengitide, an antiangiogenic agent that inhibits the binding of integrins alpha(nu)beta(3) and alpha(nu)beta(5) to the extracellular matrix, was studied at two dose levels in cancer patients to determine the optimal biological dose. PATIENTS AND METHODS: The doses of cilengitide were 600 or 1200 mg/m(2) as a 1-h infusion twice weekly every 28 days. A novel dose escalation scheme was utilized that relied upon the biological activity rate. RESULTS: Twenty patients received 50 courses of cilengitide with no dose-limiting toxic effects. The pharmacokinetic (PK) profile revealed a short elimination half-life of 4 h, supporting twice weekly dosing. Of the six soluble angiogenic molecules assessed, only E-selectin increased significantly from baseline. Analysis of tumor microvessel density and gene expression was not informative due to intrapatient tumor heterogeneity. Although several patients with evaluable tumor biopsy pairs did reveal posttreatment increases in tumor and endothelial cell apoptosis, these results did not reach statistical significance due to the aforementioned heterogeneity. CONCLUSIONS: Cilengitide is a well-tolerated antiangiogenic agent. The biomarkers chosen in this study underscore the difficulty in assessing the biological activity of antiangiogenic agents in the absence of validated biological assays.     

In vitro and in vivo clinical pharmacology of dimethyl benzoylphenylurea, a novel oral tubulin-interactive agent.

Dimethyl benzoylphenylurea (BPU) is a novel tubulin-interactive agent with poor and highly variable oral bioavailability. In a phase I clinical trial of BPU, higher plasma exposure to BPU and metabolites was observed in patients who experienced dose-limiting toxicity. The elucidation of the clinical pharmacology of BPU was sought. BPU, monomethylBPU, and aminoBPU were metabolized by human liver microsomes. Studies with cDNA-expressed human cytochrome P450 enzymes revealed that BPU was metabolized predominantly by CYP3A4 and CYP1A1 but was also a substrate for CYP2C8, CYP2D6, CYP3A5, and CYP3A7. BPU was not a substrate for the efflux transporter ABCG2. Using simultaneous high-performance liquid chromatography/diode array and tandem mass spectrometry detection, we identified six metabolites in human liver microsomes, plasma, or urine: monomethylBPU, aminoBPU, G280, G308, G322, and G373. In patient urine, aminoBPU, G280, G308, and G322 collectively represented <2% of the given BPU dose. G280, G308, G322, and G373 showed minimal cytotoxicity. When BPU was given p.o. to mice in the presence and absence of the CYP3A and ABCG2 inhibitor, ritonavir, there was an increase in BPU plasma exposure and decrease in metabolite exposure but no overall change in cumulative exposure to BPU and the cytotoxic metabolites. Thus, we conclude that (a) CYP3A4 and CYP1A1 are the predominant cytochrome P450 enzymes that catalyze BPU metabolism, (b) BPU is metabolized to two cytotoxic and four noncytotoxic metabolites, and (c) ritonavir inhibits BPU metabolism to improve the systemic exposure to BPU without altering cumulative exposure to BPU and the cytotoxic metabolites.     

alpha, beta Mannitone, a new industrial material with unknown benefits and risks.

The example is given of a new, incompletely characterized material about which information is currently incomplete. alpha, beta-Mannitone is made from old automobile tires by a secret process; it is not known whether worker exposure will occur during its production; and it is proposed for use as a substitute for petrol. The risks and benefits of this hypothetical substance must be weighed. The problems associated with such an evaluation are listed in the form of questions.     

Antineoplastic action of 5-aza-2'-deoxycytidine and histone deacetylase inhibitor and their effect on the expression of retinoic acid receptor beta and estrogen receptor alpha genes in breast carcinoma cells

PURPOSE: During tumorigenesis several cancer-related genes can be silenced by aberrant methylation. In many cases these silenced genes can be reactivated by exposure to the DNA methylation inhibitor, 5-aza-2'-deoxycytidine (5-AZA-CdR). Histone acetylation also plays a role in the control of expression of some genes. The aim of this study was to determine the antineoplastic activities of 5-AZA-CdR and trichostatin A (TSA), either administered alone or in combination. in MDA-MB-231 breast carcinoma cells. The effects of these drugs (alone and in combination) on the expression of the tumor suppressor gene, retinoic acid receptor (RAR beta) and of the estrogen receptor alpha gene (ER alpha), whose expression is lost in the cell line used in the study, were also investigated. METHODS: MDA-MB-231 cells were treated with 5-AZA-CdR and TSA and the antitumor activity of these drugs was determined by clonogenic assay. Total RNA was extracted from the treated cells and RT-PCR was used to determine the effect of the treatment on the expression of RAR beta and ER alpha. Methylation-sensitive PCR analysis was used to confirm that lack of expression of both genes was due to hypermethylation of their promoter regions. A single nucleotide primer extension assay was also used to quantify the reduction in DNA methylation following drug treatment. RESULTS: Both 5-AZA-CdR and TSA alone showed significant antineoplastic activity. The combination of the two drugs was synergistic with respect to MDA-MB-231 cell kill. 5-AZA-CdR alone weakly activated the expression of both RAR beta and ER alpha. TSA alone only activated RAR beta, but not ER alpha. The combination of these agents appeared to produce a greater activation of both genes. CONCLUSIONS: The interesting interaction between 5-AZA-CdR and TSA in both cell kill and cancer-related gene reactivation provides a rationale for the use of inhibitors of DNA methylation and histone deacetylation in combination for the chemotherapy of breast cancer.     

Differences in protein kinase C and estrogen receptor alpha, beta expression and signaling correlate with apoptotic sensitivity of MCF-7 breast cancer cell variants

Widespread use of MCF-7 human breast cancer cells as a model system for breast cancer has lead to variations in these cells between different laboratories. Although several reports have addressed these differences in terms of proliferation and estrogenic response, differences in sensitivity to apoptosis have just begun to be described. Based on the possible differences in apoptotic sensitivity that may arise due to the existence of MCF-7 cell variants, we determined the relative sensitivity of MCF-7 cell variants from three established laboratories (designated M, L and N) to known inducers of apoptosis. Consistent with our previous studies we demonstrate that differences exist among these variants in regards to tumor necrosis factor alpha (TNF)-induced cell death and inhibition of proliferation in a dose-dependent manner. To establish if the difference in apoptotic susceptibility was specific to TNF, the three MCF-7 cell variants were tested for their response to other known inducers of apoptosis: okadaic acid, staurosporine and 4-hydroxy-tamoxifen. Viability and DNA fragmentation analysis revealed a similar pattern of resistance to apoptosis by all agents in the MCF-7 M variant. The MCF-7 L variant was resistant to okadaic acid and 4-hydroxy-tamoxifen but not staurosporine. In contrast, MCF-7 N cells were sensitive to induction of apoptosis by all agents. The role of both protein kinase C (PKC) and estrogen signaling in the regulation of cell survival prompted investigation of these pathways as a mechanism for differential sensitivity of MCF-7 cell variants to apoptosis. While both estrogen receptor alpha (ERalpha) and ERbeta were expressed in MCF-7 M and N cells, the absence of ERbeta in MCF-7 L cells correlated with decreased estrogen responsiveness of the L variant. Variations in estrogenic responsiveness and PKC isoform expression may account for the enhanced susceptibility of both the L and N variants to staurosporine.     

Effective treatment of adult T cell leukemia/lymphoma with a novel oral antitumor agent, MST-16.

Adult T cell leukemia/lymphoma (ATLL) induced by human T cell leukemia virus I is resistant to conventional therapy. Six patients with ATLL were treated with a new antitumor agent, MST-16, which is a derivative of bis(2,6-dioxopiperazine). Two patients achieved complete remission, lasting 12 months and more than 8 months, and 2 others partial remission, lasting 2 months and 6 weeks, respectively. The major toxicity was myelosuppression. Other toxicities were not severe and were well tolerable. Orally administered MST-16 is a promising agent for the treatment of ATLL.     

LAS, a novel selective estrogen receptor modulator with chemopreventive and therapeutic activity in the N-nitroso-N-methylurea-induced rat mammary tumor model.

The N-nitroso-N-methylurea-induced rat mammary tumor model was used to conduct two types of studies: a prevention study designed to test the ability of the novel selective estrogen receptor modulator lasofoxifene (LAS) to inhibit the development of mammary tumors, and a treatment study designed to test the inhibitory effect of LAS on the growth of established tumors. The prevention study indicated that LAS markedly delayed the emergence of N-nitroso-N-methylurea-induced tumors to an extent similar to that obtained by the established antiestrogen tamoxifen (TAM). At the highest dose administered, both TAM and LAS reduced tumor incidence by 75% and total tumor number by 90% relative to the controls. LAS also reduced the multiplicity of tumors, i.e., the mean number of tumors per rat, and resulted in substantially smaller total tumor burden. In the treatment study, LAS significantly inhibited tumor growth compared with the controls. In addition, whereas none of the untreated tumors regressed completely over the experimental period, 40% of LAS-treated tumors regressed by >50% at the highest dose (10 mg/kg daily). The results of this study in a rat mammary tumor model indicate that LAS has both chemopreventive and chemotherapeutic effects quantitatively comparable with those of TAM.     

A Phase I and pharmacological study with imidazolium-trans-DMSO-imidazole-tetrachlororuthenate, a novel ruthenium anticancer agent.

PURPOSE: NAMI-A [H(2)Im[trans-RuCl(4)(DMSO)HIm] or imidazolium-trans-DMSO-imidazole-tetrachlororuthenate] is a novel ruthenium-containing compound that has demonstrated antimetastatic activity in preclinical studies. This Phase I study was designed to determine the maximum-tolerated dose (MTD), profile of adverse events, and dose-limiting toxicity of NAMI-A in patients with solid tumors. Furthermore, the ruthenium pharmacokinetics (PK) after NAMI-A administration and preliminary antitumor activity were evaluated. PATIENTS AND METHODS: Adult patients with solid tumors received NAMI-A as an i.v. infusion over 3 h daily for 5 days every 3 weeks. PK of total and unbound ruthenium was determined during the first and second treatment using noncompartmental pharmacokinetic analysis. The total accumulation of ruthenium in WBCs was also quantified. RESULTS: Twenty-four patients were treated at 12 dose levels (2.4-500 mg/m(2)/day). At 400 mg/m(2)/day, blisters developed on the hands, fingers, and toes. At 500 mg/m(2)/day, blisters persisted from weeks to months and slowly regressed. Although no formal common toxicity criteria (CTC) grade 3 developed, painful blister formation was considered dose limiting. Because the first signs developed at 400 mg/m(2)/day, the advised dose for further testing of NAMI-A was determined to be 300 mg/m(2)/day on this schedule. PK analysis revealed a linear relationship between dose and area under the concentration-time curve (AUC) of total and unbound ruthenium (R(2) = 0.75 and 0.96, respectively) over the whole dose range. Plasma clearance of total ruthenium was 0.17 +/- 0.09 liter/h, and terminal half-life was 50 +/- 19 h. The volume of distribution at steady state of total ruthenium was 10.1 +/- 2.8 liters. The accumulation of ruthenium in WBC was not directly proportional to the increasing total exposure to ruthenium. One patient with pretreated and progressive nonsmall cell lung cancer had stable disease for 21 weeks. CONCLUSION: NAMI-A can be administered safely as a 3-h i.v. infusion at a dose of 300 mg/m(2)/day for 5 days, every 3 weeks.     

Mitotic arrest induced by XK469, a novel antitumor agent, is correlated with the inhibition of cyclin B1 ubiquitination.

XK469 (NSC 697887) is a novel antitumor agent with broad activity against a variety of tumors. Previous studies suggest that XK469 is a topoisomerase II beta poison with functional activity similar to that of 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA). The goal of our study was to investigate its mechanism of action further using a human HCT-116 (H116) colon tumor cell model. Concentration-survival curves with continuous exposure indicated that XK469 had low cytotoxic activity against H116 cells. Cell cycle analysis revealed that XK469 is a phase-specific cell cycle blocker that is associated with increased levels of cyclin B1, cyclin A and p53 but not CDK1 (cdc2) or cyclin E. In contrast, treatment of H116 cells with m-AMSA caused a total degradation of both cyclin A and B1 but enhanced expression of cyclin E and p53. Accumulation of cyclin B1 in XK469-treated cells was correlated with the inhibition of cyclin B1 ubiquitination, a metabolic process mandatory for proteasome-mediated protein turnover. However, no inhibition of cyclin B1 ubiquitination was detected in cells treated with m-AMSA or colchicine, a known mitotic inhibitor. Furthermore, unlike m-AMSA, XK469 did not induce caspase activation or apoptotic cell death in H116 cells. Our results suggest that XK469 is a phase-specific cell cycle inhibitor with a unique mechanism of action that is correlated with the inhibition of cyclin B1 ubiquitination and its accumulation at early M phase.