Abstract P6-05-02: Endocrine biomarkers in response to AR-inhibition with bicalutamide for the treatment of AR(+), ER/PR(−) metastatic breast cancer (MBC) (TBCRC011)

Background: Our group and others have identified a subset of ER/PR(−) breast cancers characterized by expression of the androgen receptor (AR) and androgen-dependent growth (Doane 2006). We conducted a proof-of-concept multicenter phase II study to test the efficacy of the AR-antagonist, bicalutamide for the treatment of AR(+) ER/PR(−) MBC (NCT00468715). Results of the primary endpoint, clinical benefit rate (CBR), were presented at ASCO (Gucalp 2012). Data for the impact of bicalutamide on circulating hormone levels in women are limited. Elevations in serum testosterone (T) and estradiol (E) have been observed for men treated with bicalutamide. We hypothesized comparable patterns of change in circulating endocrine markers in response to bicalutamide for women with MBC.

Methods: Patients (pts) with AR(+) (IHC ≥10%), ER/PR(−) (IHC <10%) MBC were eligible for treatment (tx) if ECOG performance status ≤2 and normal organ function regardless of menopausal status. There was no limit to prior tx except prior trastuzumab required if HER2(+). Tx consisted of bicalutamide 150mg orally daily in 28-day cycles (C). Toxicity assessed q4 weeks, response q12wks. Primary endpoint was CBR. Peripheral blood was collected for total and free T, E and sex hormone binding globulin (SHBG) at baseline, start of C2 (C2) and at end of study (EOS). Standard institutional assays were used. A Wilcoxon signed-rank test was done to compare baseline to C2 and EOS values.

Results: 26 patients with AR(+) ER/PR(−) MBC were treated on study. Evaluable number (n) of pts at baseline, C2 and EOS are 26, 26 and 19 respectively. Two pts remain on study. Menopausal status: pre=2, post=24. Baseline median total and free T and estradiol were consistent with expected norms, however a wide range was observed (Table). There were no significant differences observed for median free T, total T, E or SHBG between baseline and C2 or baseline and EOS. Changes in hormone levels could not be stratified by menopausal status or response to bicalutamide given small sample size. Given the wide range of baseline values, we examined the percent change for each endocrine biomarker from baseline to C2 and EOS. As shown in the Table, there was no difference in median percent change observed across time points for each biomarker.

Males absent on the first (MOF): from flies to humans

Histone modifications such as acetylation, methylation and phosphorylation have been implicated in fundamental cellular processes such as epigenetic regulation of gene expression, organization of chromatin structure, chromosome segregation, DNA replication and DNA repair. Males absent on the first (MOF) is responsible for acetylating histone H4 at lysine 16 (H4K16) and is a key component of the MSL complex required for dosage compensation in Drosophila. The human ortholog of MOF (hMOF) has the same substrate specificity and recent purification of the human and Drosophila MOF complexes showed that these complexes were also highly conserved through evolution. Several studies have shown that loss of hMOF in mammalian cells leads to a number of different phenotypes; a G2/M cell cycle arrest, nuclear morphological defects, spontaneous chromosomal aberrations, reduced transcription of certain genes and an impaired DNA repair response upon ionizing irradiation. Moreover, hMOF is involved in ATM activation in response to DNA damage and acetylation of p53 by hMOF influences the cell's decision to undergo apoptosis instead of a cell cycle arrest. These data, highlighting hMOF as an important component of many cellular processes, as well as links between hMOF and cancer will be discussed.

MSL proteins and the regulation of gene expression

Epigenetics describes changes in genome function that occur without a change in the DNA sequence. Dosage compensation is a prime example of the regulation of gene expression by an epigenetic mechanism. Dosage compensation has evolved to balance the expression of sex-linked genes in males and females, which possess different numbers of sex chromosomes. However, the genetic sequence of the chromosomes is the same in both sexes. This mechanism therefore needs (1) to function in a sex-specific manner, (2) to target the sex chromosome from amongst the autosomes and (3) to establish and maintain through development a precise, equalised level of gene expression in one sex compared to the other. The process by which dosage compensation is orchestrated has been well characterised in fruit flies and mammals. Although each has evolved a specific dosage-compensation mechanism, these systems share some underlying themes; the molecular components that mediate dosage compensation in both include non-coding RNA molecules, which act as nucleation points for the compensation process. Both systems utilise chromatin-modifying enzymes to remodel large domains of a chromosome. This review will discuss the mechanism of dosage compensation in Drosophila in light of recent developments that have brought into question the previous model of dosage compensation.

Symptomatic fibroid uterus in a 15-year-old girl

A 15 year-old gravida 1, abortus 1 black girl presented with chief complaints of menorrhagia, severe dysmenorrhea, and progressively worsening abdominal pain, which was caused by a very large uterine leiomyoma. The symptoms began 6 months earlier, shortly after a 10-week spontaneous abortion at age 14. A solitary 25-cm uterine leiomyoma was removed uneventfully with an abdominal laparotomy. In the English literature of the past 50 years, this case represents the sixth, and we believe, the largest, documented uterine fibroid among teenagers, which required corrective surgery.

The histone H4 acetyltransferase MOF uses a C2HC zinc finger for substrate recognition

Site-specific acetylation of histone H4 by MOF is central to establishing the hyperactive male X chromosome in Drosophila. MOF belongs to the MYST family of histone acetyltransferases (HATs) characterized by an unusual C2HC-type zinc finger close to their HAT domains. The function of these rare zinc fingers is unknown. We found that this domain is essential for HAT activity, in addition to the established catalytic domain. MOF uses its zinc finger to contact the globular part of the nucleosome as well as the histone H4 N-terminal tail substrate. Point mutations that leave the zinc-finger structure intact nevertheless abolish its interaction with the nucleosome. Our data document a novel role of the C2HC-type finger in nucleosome binding and HAT activity.

Chromodomains are protein-RNA interaction modules

In Drosophila, compensation for the reduced dosage of genes located on the single male X chromosome involves doubling their expression in relation to their counterparts on female X chromosomes. Dosage compensation is an epigenetic process involving the specific acetylation of histone H4 at lysine 16 by the histone acetyltransferase MOF. Although MOF is expressed in both sexes, it only associates with the X chromosome in males. Its absence causes male-specific lethality. MOF is part of a chromosome-associated complex comprising male-specific lethal (MSL) proteins and at least one non-coding roX RNA. How MOF is integrated into the dosage compensation complex is unknown. Here we show that association of MOF with the male X chromosome depends on its interaction with RNA. MOF specifically binds through its chromodomain to roX2 RNA in vivo. In vitro analyses of the MOF and MSL-3 chromodomains indicate that these chromodomains may function as RNA interaction modules. Their interaction with non-coding RNA may target regulators to specific chromosomal sites.

Activation of transcription through histone H4 acetylation by MOF, an acetyltransferase essential for dosage compensation in Drosophila

Dosage compensation in Drosophila involves a 2-fold increase in transcription from the single male X relative to the two female X chromosomes. Regulation at the level of the chromosome involves alterations in chromatin organization: male X chromosomes appear decondensed and are marked by acetylation of histone H4 at lysine 16. We demonstrate that MOF, a protein required for dosage compensation with significant sequence similarity to the MYST family of acetyltransferases, is a histone acetyltransferase that acetylates chromatin specifically at histone H4 lysine 16. This acetylation relieves chromatin-mediated repression of transcription in vitro and in vivo if MOF is targeted to a promoter by fusion to a DNA-binding domain. Acetylation of chromatin by MOF, therefore, appears to be causally involved in transcriptional activation during dosage compensation.

Use of V79 cells with stably transfected cytochrome P450 cDNAs in studying the metabolism and effects of cytotoxic drugs

PURPOSE

Studying the metabolism of cytotoxic drugs has become increasingly necessary to predict clinically significant drug-drug interactions and to understand the basis of interindividual variations in the pharmacokinetics of anticancer agents. The aim of this study was to determine the feasibility of using V79 Chinese hamster fibroblasts, which are stably transfected with cytochrome P450 (CYP) cDNAs, to study the metabolism of cytotoxic drugs in vitro.

METHODS

The 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine cell survival after incubation with drugs. Gas chromatography/mass spectroscopy was used for the quantitation of metabolites of cyclophosphamide and ifosfamide in culture medium. The coculture technique was used to study the generation of cytotoxic metabolites in culture medium.

RESULTS

After treatment with either cyclophosphamide or ifosfamide (100 microM to 1 mM) cytotoxicity was demonstrated in only cytochrome CYP2B1- and cytochrome CYP3A4-expressing cells. Treatment of parental nontransfected cells that were cocultured with CYP-expressing cells with cyclophosphamide resulted in increased sensitivity to this drug. All active and inactive metabolites of cyclophosphamide and ifosfamide were detected in the culture medium. Cyclophosphamide-induced cytotoxicity in CYP2B1- and CYP3A4-expressing cells was abrogated by metyrapone and midazolam/ troleandomycin, respectively. Paclitaxel showed greater cytotoxicity against parental V79 cells than against the CYP2BI-, 2E1-, or 3A4-expressing cells, which was also influenced by cotreatment with CYP inhibitors.

CONCLUSIONS

Stable expression of CYP cDNAs by V79 cells provided an in vitro system to study cytotoxic drug metabolism. Cell viability and metabolite assays were used to determine the differential metabolism and effects in different CYP-transfected cell lines treated with cytotoxic drugs. The potential use of this V79 cell expression system is in studying enzymes involved in the metabolism of cytotoxic drugs, especially early in drug development. In addition, this system may be used to determine drug interactions that may influence the outcome of therapy in patients with cancer.

Serum lipids : new biological markers in depression ?

Several studies suggest that a low cholesterol concentration is associated with depression. The authors sought to determine whether an association exists between serum lipid concentrations and depression. 28 drug-naive patients of major depression diagnosed according to DSMlll- R criteria were included in the study and severity of depression was measured on Hamilton Rating Scale for Depression. Suicidal intent was assessed on Suicidal Intent Questionnaire. 28 normal healthy controls were selected and matched for age, sex and body-mass index with the depressives. Serum lipid estimations were done in each subject after 12 hours overnight fasting. The main finding of the study is that total serum cholesterol, serum triglycerides and serum LDL cholesterol are decreased while serum HDL cholesterol is increased in depression and these changes were more marked in depressed subjects with definite suicidal intent. On regression analysis, total serum cholesterol was the most important predictive variable of the severity of depression.

Successful allogeneic bone marrow transplantation in selected patients over 50 years of age--a single institution's experience

As allogeneic bone marrow transplantation (BMT) is a procedure with a higher risk of morbidity and mortality in older patients, many institutions place a limit of 50 to 55 years for allogeneic BMT. Consequently, older patients may not be offered potentially curative treatment for otherwise poor prognosis diseases such as AML or myelodysplastic syndrome. We compared the outcome of 59 patients aged over 50, 124 aged 40-50, and 253 aged 18-39 years who underwent allogeneic BMT in our institution between August 1987 and April 1996. Our results show little influence of age on outcome when comparing patients over 50 years with patients 40-50 years. Apart from an initial higher transplant mortality rate, overall survival was not significantly different between the three age groups. The 1-year and 2-year overall survival rates were 57% and 48%, 57% and 48%, and 62% and 58% for the >50 years, 40-50 years, and <40 years patients, respectively. The incidence of GVHD was also comparable. We conclude that allogeneic BMT can be performed in selected patients over the age of 50 years with acceptable morbidity and mortality and that older patients should not be denied this treatment based on age alone.

Distinct activated and non-activated RNA polymerase II complexes in yeast

We used a transcriptional run-on assay in permeabilized yeast cells to study the distribution of RNA polymerase II (pol II) complexes before and after activation by Gal4. Polymerases were found engaged on the gene at the 5' end before activation, but only appeared at the 3' end after activation. Mutations of the pol II C-terminal domain (CTD), the CTD kinase Kin28 and the holoenzyme subunit Srb2 all inhibited the formation of 3' polymerases in response to activator. However, these mutations did not inhibit the establishment of polymerases at the 5' end. The differences between 3' and 5' ternary complexes suggest that they represent qualitatively distinct 'activated' and 'non-activated' forms of polymerase. The results implicate CTD phosphorylation in a switch from 'non-activated' transcription, which is confined to the 5' end, to an 'activated' mode that traverses the length of the gene.

Isolation and characterization of the human and mouse homologues (SUPT4H and Supt4h) of the yeast SPT4 gene

To study gene regulation mediated by chromatin in mammals, we isolated the human (SUPT4H) and murine (Supt4h) counterparts of the yeast gene encoding SPT4; the product of this gene presumably interacts with the products of the mammalian homologues (which we have also cloned) of yeast SPT5 and SPT6, thereby modulating chromatin formation and activity. We isolated two different sized human SUPT4H cDNA clones (1464 and 728 nt) and one murine Supt4h (688 nt) cDNA clone; all three encode the same 117-amino-acid protein with conservation of the zinc finger motif found in SPT4. Conservation of this zinc finger motif from yeast to mouse and human implies functional importance. Although the overall sequence homology at the DNA level between the human 728-nt transcript and the murine 688-nt transcript is only 78.4%, the DNA sequence homology is 97.7% within the coding region. At the protein level, the amino acid sequences of the translated murine Supt4h and the human SUPT4H gene products are identical. The likely functional copy of SUPT4H, which has at least two introns, maps to human chromosome 17, with candidate intronless pseudogenes on chromosomes 2, 12, and 20. Buttressing the hypothesis that this is a gene required constitutively, both the human SUPT4H transcripts and the murine Supt4h transcript are expressed widely, although not at equal levels (e.g., such as most histones), in all fetal and adult tissues that we examined.

Inhibition of spontaneous metastasis in a rat prostate cancer model by oral administration of modified citrus pectin

BACKGROUND

Prostate cancer is the most common cancer diagnosed in U.S. men and remains incurable once it has metastasized. Many stages of the metastatic cascade involve cellular interactions mediated by cell surface components, such as carbohydrate-binding proteins, including galactoside-binding lectins (galectins). Modified citrus pectin (pH-modified), a soluble component of plant fiber derived from citrus fruit, has been shown to interfere with cell-cell interactions mediated by cell surface carbohydrate-binding galectin-3 molecules.

PURPOSE

The aim of this study was to determine whether modified citrus pectin, a complex polysaccharide rich in galactosyl residues, could inhibit spontaneous metastasis of prostate adenocarcinoma cells in the rat.

METHODS

The ability of modified citrus pectin to inhibit the adhesion of Dunning rat prostate cancer MAT-LyLu cells to rat endothelial cells was measured by 51Cr-labeling. Modified citrus pectin inhibition of MAT-LyLu cell anchorage-independent growth was measured by colony formation in agarose. The presence of galectin-3 in rat MAT-LyLu cells and human prostate carcinoma was demonstrated by immunoblotting and immunohistochemistry. One million MAT-LyLu cells were injected subcutaneously into the hind limb of male Copenhagen rats on day 0. Rats were given 0.0%, 0.01%, 0.1%, or 1.0% (wt/vol) modified citrus pectin continuously in their drinking water (from day 4 until necropsy on day 30). The number of MAT-LyLu tumor colonies in the lungs were counted.

RESULTS

Compared with 15 or 16 control rats that had lung metastases on day 30, seven of 14 rats in the 0.1% and nine of 16 rats in the 1.0% modified citrus-pectin group had statistically significant (two-sided; P < .03 and P < .001, respectively) reductions in lung metastases. The lungs of the 1.0% modified citrus pectin-treated rats had significantly (two-sided; P < .05) fewer metastatic colonies than control groups (9 colonies +/- 4 [mean +/- SE] in the control group compared with 1 colony +/- 1 in the treated group). Modified citrus pectin had no effect on the growth of the primary tumors. In vitro, modified citrus pectin inhibited MAT-LyLu cell adhesion to rat endothelial cells in a time- and dose-dependent manner as well as their colony formation in semisolid medium.

CONCLUSIONS

We present a novel therapy in which oral intake of modified citrus pectin acts as a potent inhibitor of spontaneous prostate carcinoma metastasis in the Copenhagen rat.

IMPLICATIONS

Further investigations are warranted to determine the following: 1) the role of galectin-3 in normal and cancerous prostate tissues and 2) the ability of modified citrus pectin to inhibit human prostate metastasis in nude mice.

Factors that facilitate compliance to lower fat intake

The success of dietary interventions that are prescribed to reduce the risk of heart disease depends on the degree to which patients actually change their diets. A review of research trials using different diets and various means of fostering dietary change to reduce cardiac risk factors identified specific factors that are associated with a greater degree of dietary change. Contrary to the common conception that strict diets are unacceptable to patients, those research studies that set stricter limits on fat intake achieved a greater degree of dietary change than did studies with more modest goals. Additional factors used by studies that achieved a lower fat intake include monitoring dietary intake at least monthly, family involvement, group support, provision of food, initial residential treatment, the use of vegetarian diets, and symptomatic subjects. These factors may be useful to researchers and to clinicians seeking to improve dietary compliance in patients.

Preclinical studies of gossypol in prostate carcinoma

Hormone refractory prostate cancer remains an incurable disease and the discovery of newer agents with higher cytotoxic activity is required. Gossypol is a phenolic compound isolated from cottonseed oil which has been shown to have anti-spermatogenic effects. In in vitro studies, gossypol appears to inhibit the growth of rat prostate cancer cell line MAT-LyLu and human prostate adenocarcinoma cell lines PC-3, LNCaP and DU-145. In vive, gossypol appeared to inhibit tumor growth of subcutaneously implanted MAT-LyLu cells in Copenhagen rats. Gossypol may be an active agent for the treatment of hormone refractory metastatic prostate cancer.

Oral cyclophosphamide and oral hydroxyurea in the treatment of hormone refractory prostate cancer in rats

Hormone refractory prostate cancer is a fatal disease and currently no standard cytotoxic chemotherapy exists for prostate cancer. The recent use of prostate specific antigen as an endpoint for clinical trial has resulted in the ability to test the activity of chemotherapy agents in a quick manner. The aim of this study was to investigate the activity of the oral combination of two familiar agents, cyclophosphamide and hydroxyurea, against hormone refractory prostate cancer. In vitro studies demonstrated that hydroxyurea was more active than cyclophosphamide against the anaplastic Dunning rat prostate cancer cell line, Mat-LyLu. In vivo experiments, however, demonstrated cyclophosphamide to be superior to hydroxyurea. The combination of both agents failed to enhance inhibition of subcutaneously implanted Mat-LyLu cells. A human trial of oral cyclophosphamide using prostate specific antigen as an intermediate endpoint may be warranted.

Bryostatin 1-induced hairy cell features on chronic lymphocytic leukemia cells in vitro

The phorbol esters induce differentiation of chronic lymphocytic leukemia (CLL) cells. Clinical use of this observation has been hampered by the fact that phorbol esters are also tumor promoters. In this study we demonstrate that another protein kinase C activator, without tumor promoting activity, has similar effects on CLL cells. Fresh leukemic cells from the peripheral blood of 13 patients with CLL were isolated and cultured in the absence (control) or presence of Bryostatin 1 or 12-0-tetradecanoylphorbol 13-acetate (TPA). Aliquots of cells were then analyzed after 24, 72 and 120 hours for morphological changes, acid phosphatase (ACP) and the co-expression of two hairy cell-associated surface antigens, CD22 and CD11c, by flow cytometry. Bryostatin 1 induced changes in shape and morphology similar to TPA, with adherence and increase in cell size, abundant cytoplasm and irregular cytoplasmic membrane. Both agents induced a statistically significant increase in the expression of CD22 and CD11c compared with control (p < 0.0008). There was no significant difference between the two agents in the degree of expression of these two markers. Both agents also induced ACP that was tartrate resistant (TRAP). These changes indicate that Bryostatin is as effective as TPA in inducing further differentiation of CLL cells to a hairy cell stage.