Effect of polymorphism of the beta(2)-adrenergic receptor on response to regular use of albuterol in asthma

BACKGROUND

Regular use of inhaled beta-adrenergic agonists may have adverse effects in some asthma patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect its regulation; however, results of smaller studies of the effects of such polymorphisms on response to beta-agonist therapy have been inconsistent.

METHODS

We examined the possible effects of polymorphisms at codons 16 (beta(2)-AR-16) and 27 (beta(2)-AR-27) on response to albuterol by genotyping 190 asthmatics who had participated in a trial of regular versus as-needed albuterol use.

RESULTS

During the 16-week treatment period, patients homozygous for arginine (Arg/Arg) at beta(2)-AR-16 who used albuterol regularly had a small decline in morning peak expiratory flow (AM PEF). This effect was magnified during a 4-week run-out period, when all patients returned to as-needed albuterol only. By the end of the study, Arg/Arg subjects who had used albuterol regularly had an AM PEF 30.5 +/- 12.1 liters/min lower (p = 0.012) than Arg/Arg patients who had used albuterol as needed only. Subjects homozygous for glycine at beta(2)-AR-16 showed no such decline. Evening PEF also declined in the Arg/Arg regular but not in as-need albuterol users. No significant differences between regular and as-needed treatment were associated with polymorphisms at beta(2)-AR-27.

CONCLUSIONS

Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

The effect of polymorphisms of the beta(2)-adrenergic receptor on the response to regular use of albuterol in asthma

Inhaled beta-adrenergic agonists are the most commonly used medications for the treatment of asthma although there is evidence that regular use may produce adverse effects in some patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect regulation of the receptor. Smaller studies examining the effects of such polymorphisms on the response to beta-agonist therapy have produced inconsistent results. We examined whether polymorphisms at codon 16 (beta(2)-AR-16) and codon 27 (beta(2)-AR-27) of the beta(2)-AR might affect the response to regular versus as-needed use of albuterol by genotyping the 190 asthmatics who had participated in a trial examining the effects of regular versus as needed albuterol use. During the 16-wk treatment period there was a small decline in morning peak expiratory flow in patients homozygous for arginine at B(2)-AR-16 (Arg/Arg) who used albuterol regularly. This effect was magnified during a 4-wk run out period, during which all patients returned to using as-needed albuterol, so that by the end of the study Arg Arg patients who had regularly used albuterol had a morning peak expiratory flow 30. 5 +/- 12.1 L/min lower (p = 0.012) than Arg/Arg patients who had used albuterol on an as needed basis. There was no decline in peak flow with regular use of albuterol in patients who were homozygous for glycine at beta(2)-AR-16. Evening peak expiratory flow also declined in the Arg/Arg patients who used albuterol regularly but not in those who used albuterol on an as-needed basis. No significant differences in outcomes between regular and as-needed treatment were associated with polymorphisms at position 27 of the beta(2)-AR. No other differences in asthma outcomes that we investigated occurred in relation to these beta(2)-AR polymorphisms. Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

A pilot trial of 13-cis-retinoic acid and alpha-tocopherol with recombinant human erythropoietin in myelodysplastic syndrome patients with progressive or transfusion-dependent anemias. The Central Pennsylvania Oncology Group

A pilot study was performed to determine the efficacy of 13-cis-retinoic acid (CRA) and alpha-tocopherol (AT) with increasing doses of recombinant human erythropoietin (rHuEPO) in anemic patients with primary myelodysplastic syndrome (MDS), to determine response rate and to determine the dose requirement and long-term effects of rHuEPO therapy on the transition to acute non-lymphocytic anemia and survival of these patients. Twenty-four consecutive MDS patients were entered into the study. Patients were stratified according to their FAB classification at study entry. Therapy consisted of a 6 month trial of CRA (100 mg m(-2) day(-1) and AT (800 mg day(-1)) with rHuEPO (150 units kg(-1) body weight subcutaneously three times a week). The rHuEPO dose was escalated to daily doses at 2 months, and 300 U kg(-1) body weight given three times a week for another 2 months and continuing therapy after 6 months in responsive patients. Response was measured by elimination of transfusions requirement (partial response, PR) and normal hemoglobin level and complete blood counts (complete response, CR). Observed responses for the 23 evaluable patients were 2 CR and 6 PR (34.8%). Odds ratio analysis showed that patients with anemia alone were 14 times more likely to respond than patients with pancytopenia (p = 0.06). In our study, two patients (8%) transformed to acute leukemia in CRA + AT + rHuEPO-treated patients. Median survival of 34 months with a median follow-up of 17 months (range 3-70 months) was observed. The response rates with the addition of rHuEPO to CRA and AT was similar but occurs earlier at 2 months compared to 6-10 months with CRA and AT alone and did not alter survival. There was no increase in the risk for leukemia in the group treated with rHuEPO. Response to either therapy appeared to be limited to patients in the early stages of MDS.

Diversity of pubertal testosterone changes in boys with constitutional delay in growth and/or adolescence

In a group of 22 boys with constitutional delay in growth and/or adolescence, intermittent testosterone enanthate treatment was employed in a randomized clinical trial at multiple doses ranging from 25-100 mg every two weeks for three month periods extending over 15-21 months. Twelve of the patients displayed a prompt increase in endogenous testosterone levels during the study period, reaching levels in the adult male range (> 250 ng/dl). The remaining 10 boys showed sluggish changes in endogenous testosterone during the investigation, ranging from 35-177 ng/dl. The bone ages and testicular sizes of the two groups at study initiation did not differ though urine LH was significantly less at study entry in the slowly maturing group. The data reveal a great diversity in the pace and pattern of endogenous testosterone changes in the study population. The results also suggest that exogenous sex steroid treatment of such patients does not speed up the central nervous system processes controlling the onset and progression of puberty. Boys with delayed puberty should be followed until endogenous testosterone levels reach the adult male range in order to rule out mild gonadotropin deficits.

Induction of a less aggressive breast cancer phenotype by protein kinase C-alpha and -beta overexpression

To address the isoenzyme-specific involvement of protein kinase C (PKC) in breast cancer biology, hormone-responsive MCF-7 breast cancer cells were infected with either PKC-alpha or -beta 1 cDNAs subcloned in the retroviral expression vector pMV7. Several stable clones of PKC-overexpressing cells were generated. Western analysis revealed cross-regulation between the alpha and beta isoforms, because induction of overexpression of one up-regulated the other. Overexpression of the alpha and beta isoenzymes, on the other hand, did not affect the already high endogenous expression of the novel delta, epsilon, eta, and zeta isoforms. Compared with control clones, PKC-alpha- and -beta-overexpressing MCF-7 cells exhibited more drastic morphological changes in response to phorbol 12-myristate 13-acetate administration characterized by cellular flattening and vacuolization. More importantly, induction of PKC-alpha and -beta overexpression induced a less aggressive biological behavior, which was characterized by reduced in vitro invasiveness and markedly diminished tumor formation and growth in nude mice. These in vivo findings can probably best be explained by the dramatic down-regulation of estrogen receptor levels observed in tumors derived from PKC-alpha-infected MCF-7 cells. Our data clearly show that it is possible to induce a less aggressive breast cancer phenotype by altering PKC isoenzyme expression.

Isolation and characterization of human breast cancer cells overexpressing S-adenosylmethionine decarboxylase

We report the first successful isolation and initial characterization of S-adenosylmethionine decarboxylase (SAMDC)-overexpressing cells using a transfection approach. Stably transfected MCF-7 breast cancer overproducing SAMDC (approximately 5-fold) manifested reduced ornithine decarboxylase while levels of N'-spermidine/spermine acetyltransferase were variably increased. Analysis of cellular polyamine profile showed that spermine was selectively increased (approximately 80%), while spermidine and putrescine levels were reduced (approximately 48% and approximately 15% of control, respectively). Since SAMDC-overexpressing clones exhibited increased clonogenicity in soft agar, our data suggest that spermine may be selectively involved in conferring a more invasive phenotype to breast cancer cells.

Biochemical and growth-modulatory effects of the new S-adenosylmethionine decarboxylase inhibitor CGP 48664 in malignant and immortalized normal human breast epithelial cells in culture

CGP 48664 [4-aminoindanon-1-(2'-amidino)hydrazone dihydrochloride monohydrate] is a newly introduced inhibitor of S-adenosylmethionine decarboxylase (SAMDC) with increased selectivity of action and reduced toxicity. We analyzed the biochemical and antiproliferative effects of this compound in a panel of hormone-dependent (3 clones of MCF-7, T47D) and -independent (MDA-MB-231, BT-20) human breast cancer cell lines in culture. For comparison, we also tested its effects in the spontaneously immortalized human breast epithelial cell line MCF-10A. All cell lines were highly sensitive to the growth-inhibitor effect of CGP 48664 with an IC50 between 0.1 and 0.5 microM. A dose-dependent bell-shaped increase in SAMDC was observed in normal and malignant breast cells resulting from enzyme stabilization by the inhibitor as supported by Western blot analysis. While ornithine decarboxylase (ODC) activity consistently increased, the effect of CGP 48664 on spermidine/spermine N'acetyltransferase (SSAT) was variable in the breast cancer cell lines. In contrast, the inhibitor consistently reduced SSAT activity level in the MCF-10A cell line and its derivative partially transformed by a mutated ras oncogene. As expected cellular putrescine levels were markedly increased by CGP 48664 administration, whereas spermidine and spermine contents were reduced. However, the degree of reduction was usually only moderate. Furthermore, exogenous polyamine administration was relatively ineffective in rescuing the antiproliferative effect of CGP 48664 in MCF-7 cells, while exerting a more complete rescue in the MDA-MB-231 cell line. We conclude that CGP 48664 exerts a potent growth-inhibitory effect on mammary cells in culture. However, its action may not always be entirely mediated through the polyamine pathway.

Involvement of the polyamine pathway in breast cancer progression

These experiments were designed to test the role of the polyamine pathway in breast cancer progression utilizing an experimental system based on the development of ovary-independent rat mammary tumors and their sequential transplantation into syngeneic hosts. Three key enzymes involved in the PA biosynthetic/catabolic pathway (ornithine-decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), and spermidine/spermine N'-acetyltransferase (SSAT)) were measured in tumors at different stages of progression. The most significant finding was the association between increased ODC activity and the acquisition of a hormone-independent, poorly differentiated phenotype. SSAT levels tended to be higher in hormone-independent tumors and, in this tumor category, they tended to be positively correlated with differentiation. However, significant interaction between hormone dependence and differentiation status on SSAT expression prevented reliable assessment of the possibly complex role of this enzyme in tumor progression. Neither hormone dependence nor differentiation status were correlated with SAMDC levels. We conclude that, among the three enzymes tested, ODC overexpression is the most significant alteration in the PA metabolic pathway associated with breast cancer progression in this experimental system.

Time until first significant difference in in vivo tumor growth experiments

In in vivo tumor growth experiments it is common to report the tumor measurement time at which the volume distributions of the treatment groups become significantly different. This method of analysis, as commonly practiced, is deficient in that its type I error rate exceeds the usual nominal rate of 5%, unless one specifically corrects for multiple comparisons. A second problem is that many investigators evidently interpret the time of first significance as a statistical parameter--i.e., a fixed but unknown property of the model that one can estimate by experimentation. In fact the time until first significance, like the power of the test, depends both on true model parameters (such as mean growth curves and experimental variability) and on features of the experimental design, such as the sample size and the spacing of the measurement times. We argue that investigators would do better to compare treatment groups by modeling tumor growth curves or estimating volume doubling times.

The management of patients with advanced carcinoid tumors and islet cell carcinomas

OBJECTIVE

To determine the effectiveness of hepatic artery occlusion alone and with sequenced chemotherapy for patients with hepatic-dominant metastases of islet cell carcinomas and carcinoid tumors.

DESIGN

Nonrandomized, observational study with follow-up from 2.5 to 10 years.

PATIENTS

111 ambulatory patients referred to a multidisciplinary tertiary care center who had histologically proven islet cell carcinoma or carcinoid tumor and symptomatic measurable metastatic lesions in the liver or hormonal abnormalities or both. The patients were ambulatory but were having substantial symptoms because of their endocrine syndromes or their tumors.

INTERVENTION

All patients had hepatic artery occlusion done surgically or by catheterization and embolization. After this procedure, 71 patients were selected for chemotherapy with alternating two-drug regimens of doxorubicin plus dacarbazine and streptozocin plus fluorouracil. Main outcome measures of response to therapy were rates of tumor regression, rates of improvement in endocrine abnormalities, symptomatic improvement, and duration of favorable response.

RESULTS

Objective regressions were observed in 60% of patients treated with occlusion alone and in 80% with chemotherapy added. Regressions were associated with substantial or complete relief from the endocrine syndromes. With occlusion alone, the median duration of regression was 4.0 months and with chemotherapy added, it was 18.0 months. Any comparative inferences about the two treatment regimens must be guarded, because this was not a randomized trial and marked differences occurred in the distribution of prognostic factors between the patient groups. Side effects of arterial occlusion included fever, nausea, pain, and abnormalities in liver function. Side effects of chemotherapy included nausea, vomiting, leukopenia, and alopecia.

CONCLUSIONS

Hepatic arterial occlusion can frequently produce major regression of neuroendocrine tumors with relief from the hormonal syndromes. Sequential chemotherapy may improve the rate and duration of the regression.