Genotypic and allelic frequencies of SULT1A1 polymorphisms in women receiving adjuvant tamoxifen therapy

Human sulfotransferase 1A1 (SULT1A1) is involved in the metabolism of a number of substances including 4-hydroxytamoxifen. It has been shown that patients who are homozygous for the variant SULT1A1 *2/*2 have lower catalytic activity. Previous data has suggested that patients with this particular genotype may be at a greater risk of developing breast cancer or not responding to tamoxifen therapy. To date, there is no data within the Hispanic population on the genotypic and allelic frequencies of the SULT1A1 gene. Two hundred and ninety-six patients were genotyped by either restriction fragment length polymorphism (RFLP) or Pyrosequencing for the SULT1A1 exon 7 polymorphism. The genotypic frequency was 0.47 (*1/*1), 0.40 (*1/*2) and 0.13 (*2/*2) in Caucasians and 0.37 (*1/*1), 0.45 (*1/*2) and 0.18 (*2/*2) in Hispanics. Although Hispanics have a higher genotypic frequency of variant genotypes this difference was not statistically significant (p=0.26). SULT1A1 genotype did not correlate with any prognostic or predictive markers associated with breast cancer. Future evaluations will assess the functional significance of this polymorphism on survival.

Relationship between CYP2D6 and estrogen receptor alpha polymorphisms on tamoxifen metabolism in adjuvant breast cancer treatment

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Background: Tamoxifen (TAM) and its metabolites display large inter-individual variation with profound implications for breast cancer outcomes. Tamoxifen is hydroxylated to the potent metabolites, 4-hydroxytamoxifen (4-OH TAM) and endoxifen, by various cytochrome P450 (CYP450) genes including CYP2C9 and CYP2D6. The SULT1A1 gene is involved in the conjugation of 4-OH TAM. Tamoxifen’s binding site is the estrogen receptor (ER). Methods: Clinical data and blood samples were collected for 301 patients (299 female, 2 male) receiving at least 8 weeks of adjuvant tamoxifen therapy. HPLC analysis assessed TAM, N-desmethyltamoxifen (N-DMT), and 4-OH TAM levels. Genotyping of the CYP2C9 (*2,*3), CYP2D6 (*2, *3, *4, *6, *7, *8, *14) and SULT1A1 (*2) genes was determined by Pyrosequencing. CYP2D6 genotypes were subdivided into poor (PM), intermediate (IM), and extensive (EM) metabolizers. Genotyping of ER alpha polymorphisms, Pvu II and Xba I, utilized a Taqman Allelic Discrimination Assay. The Wilcoxon Rank Sum test was used to test associations of genotype and quantitative metabolite levels, within genotype associations, and ethnicity. Results: The majority of our patients were Caucasian (68%) and Hispanic (26%). The mean (± SD) levels for TAM, 4-OH TAM and N-DMT were 111.7 (± 58.4 ng/ml), 2.2 (± 1.5 ng/ml) and 204.7 (± 104.1 ng/ml), respectively. The CYP2D6 genotype was statistically associated with 4-OH TAM levels (p=0.0002). Differences were detected between EM and PM (p=0.0001) and IM and PM (p=0.0029). ER alpha Pvu II genotypes were shown to influence TAM levels (p=0.02). Significant differences were identified between the PP and Pp genotypes (p=0.0064) and between PP and pp genotypes (p=0.03). Hispanics had significantly higher levels of TAM (p=0.02) and 4-OH TAM (p=0.007) than Caucasians. Conclusions: Genotype and ethnicity are significantly associated with levels of TAM and 4-OH TAM and may explain clinical variation in response to TAM treatment.

No significant financial relationships to disclose.

Phase I and pharmacokinetic study of the differentiating agent vesnarinone in combination with gemcitabine in patients with advanced cancer

PURPOSE

To evaluate the maximum-tolerated dose, dose-limiting toxicities (DLTs), and pharmacokinetic profile of vesnarinone given once daily in combination with gemcitabine.

PATIENTS AND METHODS

Twenty-six patients were treated with oral vesnarinone once daily on a continuous schedule at doses of 60, 90, 120, 150, and 180 mg in combination with intravenous (IV) gemcitabine at a dose of 1,000 mg/m(2) on days 1, 8, and 15 every 4 weeks. To determine whether biologically relevant concentrations were being achieved, predose concentrations (C(min)) of vesnarinone were obtained weekly. Plasma gemcitabine and 2',2'-difluorodeoxyuridine concentrations were obtained during courses 1 and 2.

RESULTS

Twenty-six patients were treated with 92 courses of vesnarinone/gemcitabine. The principal toxicities of the regimen consisted of neutropenia and thrombocytopenia, which were dose-limiting in two of eight heavily pretreated new patients treated at the 90 mg/1,000 mg/m(2) dose level and one of 10 minimally pretreated new patients at the 120 mg/1,000 mg/m(2) dose level. None of three patients treated with 15 courses at the vesnarinone/gemcitabine dose levels of 60 mg/1,000 mg/m(2) experienced DLT. Pharmacokinetic studies of vesnarinone revealed significant interpatient variability at any given dose level. There was evidence of a linear relationship between vesnarinone dose and mean C(min) at dosages of vesnarinone less than 150 mg, with plateauing of mean C(min) values at higher dosages. There was no impact of vesnarinone on gemcitabine concentrations, and the vesnarinone pharmacokinetics did not change with gemcitabine between weeks 1 and 2. Two partial responses occurred in patients with refractory breast and non-small-cell lung carcinoma.

CONCLUSION

When combined with gemcitabine, the recommended dose of vesnarinone for phase II evaluations is 90 mg orally once daily with gemcitabine 1,000 mg/m(2) IV on days 1, 8, and 15 every 4 weeks. There is no evidence of pharmacokinetic interaction between vesnarinone and gemcitabine. Further studies of vesnarinone as a single agent or in combination with gemcitabine and other antineoplastic agents are warranted.

Phase I and pharmacologic study of PN401 and fluorouracil in patients with advanced solid malignancies

PURPOSE

To assess the feasibility of administering PN401, an oral uridine prodrug, as a rescue agent for the toxic effects of fluorouracil (5-FU), and to determine the maximum-tolerated dose of 5-FU when given with PN401, with an 8-hour treatment interval between these agents.

PATIENTS AND METHODS

Patients with advanced solid malignancies were treated with escalating doses of 5-FU, given as a rapid intravenous infusion weekly for 3 consecutive weeks every 4 weeks. PN401 was administered orally 8 hours after 5-FU administration, to achieve sustained plasma uridine concentrations of at least 50 micromol/L. Initially, patients received 6 g of PN401 orally every 8 hours for eight doses (schedule 1). When dose-limiting toxicity (DLT) was consistently noted, patients then received 6 g of PN401 every 2 hours for three doses and every 6 hours thereafter for 15 doses (schedule 2).

RESULTS

Twenty-three patients received 50 courses of 5-FU and PN401. Among patients on schedule 1, DLT (grade 4 neutropenia complicated by fever and diarrhea) occurred in those receiving 5-FU 1,250 mg/m(2)/wk. Among patients on schedule 2, 5-FU 1,250 mg/m(2)/wk was well tolerated, but grade 4, protracted (> 5 days) neutropenia was consistently noted in those treated with higher doses of the drugs. Nonhematologic effects were uncommon and rarely severe. The pharmacokinetics of 5-FU, assessed in 12 patients on schedule 2, were nonlinear, with the mean area under the time-versus-concentration curve (AUC) increasing from 298 +/- 44 to 962 +/- 23 micromol/L and mean clearance decreasing from 34 +/- 4 to 15.6 +/- 0.38 L/h/m(2) as the dose of 5-FU was increased from 1,250 to 1,950 mg/m(2)/wk. 5-FU AUCs achieved with 5-FU 1,250 mg/m(2)/wk for 6 weeks along with the intensified PN401 dose schedule were approximately five-fold higher than those achieved with 5-FU alone. Plasma uridine concentrations increased with each of the three PN401 doses given every 2 hours, and uridine steady-state concentrations were greater than 50 micromol/L.

CONCLUSION

Treatment with oral PN401 beginning 8 hours after 5-FU administration is well tolerated and results in sustained plasma uridine concentrations above therapeutic-relevant levels. The recommended 5-FU dosage for phase II evaluations is 1,250 mg/m(2)/wk for 3 weeks every 4 weeks with the intensified PN401 dose schedule (schedule 2). At this dose, systemic exposure to 5-FU as measured by AUC was five-fold higher than that observed after administration of a conventional 5-FU bolus.

Piccolo, a presynaptic zinc finger protein structurally related to bassoon

Piccolo is a novel component of the presynaptic cytoskeletal matrix (PCM) assembled at the active zone of neurotransmitter release. Analysis of its primary structure reveals that Piccolo is a multidomain zinc finger protein structurally related to Bassoon, another PCM protein. Both proteins were found to be shared components of glutamatergic and GABAergic CNS synapses but not of the cholinergic neuromuscular junction. The Piccolo zinc fingers were found to interact with the dual prenylated rab3A and VAMP2/Synaptobrevin II receptor PRA1. We show that PRA1 is a synaptic vesicle-associated protein that is colocalized with Piccolo in nerve terminals of hippocampal primary neurons. These data suggest that Piccolo plays a role in the trafficking of synaptic vesicles (SVs) at the active zone.

The effects of Escherichia coli S-fimbriae and outer membrane protein A on rat pial arterioles

Cerebral vascular injury is common in bacterial meningitis, but the role of microbial factors associated with this phenomenon is unclear. Escherichia coli S-fimbriae and outer membrane protein A (OmpA) have been shown to promote binding and invasion of E. coli to brain microvascular endothelial cells, respectively. Using the cranial window model, we compared the response of pial arterioles in experimental animals exposed to E. coli with and without S-fimbriae or OmpA after intracarotid injection to animals receiving saline (control). After 3 h, pial arteriolar diameter had progressively increased to 144 +/- 23 (SD)% of the baseline value in animals exposed to S-fimbriated E. coli and to 131 +/- 12% of the baseline value in animals exposed to nonfimbriated E. coli. Analysis of variance with Bonferroni post hoc comparisons revealed that at 2 h the pial arteriolar response to S-fimbriated E. coli was significantly different from control (p = 0.0142). After 3 h, the S-fimbriated E. coli group was significantly different from both the control and the nonfimbriated group (p = 0.0024 and 0.0163, respectively). The nonfimbriated group showed a trend of progressive vasodilation, which was not significantly different from the control. After 3 h, pial arteriolar diameter progressively increased to 156 +/- 14% of baseline in animals exposed to OmpA+ E. coli and 151 +/- 24% of baseline to OmpA- E. coli. The vasodilatory response to OmpA+ and OmpA- E. coli was statistically different from control (p = 0.0004 and 0.0010, respectively) but not different from each other. These data suggest that, although cerebral vasodilatory response to E. coli is multifactorial, binding plays an important role in initiating the vasodilation and bacterial invasion does not enhance the vasodilatory response in the cerebral microvasculature.

Piccolo, a novel 420 kDa protein associated with the presynaptic cytomatrix

In this study, we describe a novel 420 kDa protein, called Piccolo, found at a wide variety of adult rat brain synapses. High protein levels in the cerebellum, the olfactory bulb and the hippocampus were frequently observed to be associated with asymmetric type 1 synapses. Piccolo is selectively enriched in presynaptic terminals, but is not a component of synaptic vesicles (SVs). Immunogold electron microscopy revealed that Piccolo localizes to the amorphous material among SVs at the presynaptic plasma membrane. Biochemical studies showed that it is very tightly bound to this structure. Thus, we speculate that Piccolo is a structural component of the presynaptic cytomatrix which anchors SVs to the presynaptic plasmalemma.

SAP90, a rat presynaptic protein related to the product of the Drosophila tumor suppressor gene dlg-A

A novel synapse-associated protein, SAP90, accumulates around the axon hillock of Purkinje cells in rat cerebellum. By immuno-electron microscopy, SAP90 has been localized to the presynaptic termini of basket cells forming inhibitory, gamma-aminobutyric acid (GABA)ergic synapses onto Purkinje cell axon hillocks. The amino acid sequence for SAP90 has been deduced from the nucleotide sequence of a series of overlapping cDNA clones. SAP90 is related to the gene product encoded by the Drosophila tumor suppressor gene dlg-A. SAP90 and the dlg-A product share an overall sequence identity of 54%. Three distinct domains can be identified: (i) a potential cytoskeletal region consisting of three repeats of 90 amino acids in length, (ii) a domain with similarity to SH3, a putative regulatory motif found in the src family of non-receptor protein tyrosine kinases and several proteins associated with the cortical cytoskeleton, and (iii) a carboxyl-terminal domain homologous to yeast guanylate kinase. These features suggest a possible role for SAP90 in a guanine nucleotide-mediated signal transduction pathway at a subset of GABAergic synapses in the rat cerebellum.

Cytotoxic T lymphocytes against a soluble protein

Thymus-derived (T) lymphocytes recognize antigen in conjunction with surface glycoproteins encoded by major histocompatibility complex (MHC) genes. Whereas fragments of soluble antigens are presented to T helper lymphocytes (TH), which carry the CD4 antigen, in association with class II MHC molecules, CD8-bearing cytotoxic T lymphocytes (CTL) usually see cellular antigens (for instance virally-encoded proteins) in conjunction with MHC class I molecules. The different modes of antigen presentation may result from separate intracellular transport: vesicles containing class II molecules are thought to fuse with those carrying endocytosed soluble proteins. Class I molecules, in contrast, can only pick up degradation products of intracellular proteins (see refs 7 and 8). This makes biological sense; during an attack of a virus, class I-restricted CTL destroy infected cells and class II-restricted TH guide the humoural response to neutralize virus particles and toxins. But here we provide evidence that CTL specific for ovalbumin fragments can be induced with soluble protein, and that intracellular protein degradation provides epitopes recognized by these CTL. These findings suggest the existence of an antigen presenting cell that takes up soluble material and induces CTL.

Use of play materials in treating a severely handicapped child

A 4-year-old boy with a physical handicap severe enough to preclude his manipulating materials, participated in a play intervention designed to help him to deal with some of his limitations. His skill in communicating to the therapist and in utilizing vicarious experiences allowed him to participate fully and successfully in therapy, although several modifications had to be made in the usual play procedures. The basic techniques of play therapy may therefore be of use to other motorically handicapped children who are capable of verbalizing and fantasizing. During the course of the therapy, this child also evidenced some unusual perceptions of the world. The lack of opportunity to have the customary sensorimotor experiences had apparently delayed his development of object permanence. This finding is consistent with Piaget's theory, which emphasized early motoric behaviours as prerequisites to later intellectual operations.