T. Thorsen

Gene expression patterns of breast carcinomas distinguish tumor subclasses with clinical implications

The purpose of this study was to classify breast carcinomas based on variations in gene expression patterns derived from cDNA microarrays and to correlate tumor characteristics to clinical outcome. A total of 85 cDNA microarray experiments representing 78 cancers, three fibroadenomas, and four normal breast tissues were analyzed by hierarchical clustering. As reported previously, the cancers could be classified into a basal epithelial-like group, an ERBB2-overexpressing group and a normal breast-like group based on variations in gene expression. A novel finding was that the previously characterized luminal epithelial/estrogen receptor-positive group could be divided into at least two subgroups, each with a distinctive expression profile. These subtypes proved to be reasonably robust by clustering using two different gene sets: first, a set of 456 cDNA clones previously selected to reflect intrinsic properties of the tumors and, second, a gene set that highly correlated with patient outcome. Survival analyses on a subcohort of patients with locally advanced breast cancer uniformly treated in a prospective study showed significantly different outcomes for the patients belonging to the various groups, including a poor prognosis for the basal-like subtype and a significant difference in outcome for the two estrogen receptor-positive groups.

Premorbid body weight and its relations to primary tumour diameter in breast cancer patients; its dependence on estrogen and progesteron receptor status

Hormonal mechanisms have been offered as an explanation for the higher frequency of large tumours, lymph node metastases and poorer prognosis in obese breast cancer patients than in lean ones. If hormonal mechanisms are important for these relations, they should probably act more strongly in patients with hormonal receptor positive tumours than in those with negative ones. We have examined if the relations between premorbid body weight or Quetelets index (weight/height2) and tumour diameter are modified by estrogen receptor alpha (ER) and progesteron receptor (PgR) status. The analyses were based on 1,241 women with unilateral disease treated with modified radical mastectomy living in the geografic area of Haukeland Hospital. Their body weight and height have been measured as a mean 12.5years before presentation of the disease. Body weight and Quetelets index have been adjusted for age. The relations were studied using linear regression analyses adjusting the effect of body weight with height and mean nuclear area of the tumour cells and adjusting the effect of Quetelets index for mean nuclear area. The main findings showed that patients with high body weight or Quetelets index presented more often with PgR positive tumours than lean ones. Quetelets index was also positively related to ER. These relations were present in patients older than 50 years of age (older). Patients with large tumours (>2.0cm) had significantly higher body weight and Quetelets index than those with small ones. These differences were significantly present in older patients and in patients with PgR negative and ER negative – PgR negative tumours. Linear regression analyses confirmed that tumour diameter increases with body weight and Quetelets index. These relations were present in both lymph node groups and in older patients. Stratification according to hormonal receptor status showed these relations to be significant in patients with ER negative, with PgR negative and those with ER negative – PgR negative tumours only. Taking age and hormonal receptor status into consideration simultaneously, both body weight and Quetelets index were significantly related to tumour diameter in older patients with hormone receptor negative tumours. In conclusion body size was positively related to hormone receptor status and to diameter of the primary tumour. The relation to tumour diameter was present in older patients with hormone receptor negative tumours. Although hormonal mechanisms able to act on the tumour can not be excluded, mechanisms acting independent of hormonal receptors must be considered. Different mechanisms related to body fat cytokines are discussed.

Oestradiol treatment increases the sensitivity of MCF-7 cells for the growth stimulatory effect of IGF-I

MCF-7 cells were grown in serum free medium (Dulbecco MEM without phenol red, supplemented with Costar SF-1 without insulin). Insulin was added as required and gave dose dependent growth stimulation at concentrations between 5 and 10,000 nM. Identical growth response curves were obtained for thymidine uptake and cell number. Oestradiol and insulin-like growth factor I (IGF-I) added individually both gave a dose dependent stimulation of cell growth in serum free medium containing 50 nM insulin. The growth stimulatory effect of oestradiol was to a large extent inhibited with suramine, a general inhibitor of growth factors, indicating that the effect of oestradiol was mediated through stimulating autocrine secretion of a growth factor. To investigate a possible link between the effects of oestradiol and IGF-I, a specific IGF-I receptor antibody (alpha IR-3), 10 micrograms/ml was used. These experiments were carried out with 2.5 nM insulin in the medium, a concentration at which insulin had no growth stimulatory effect. Stimulation was carried out for 18 h before assay of thymidine uptake. The effect of oestradiol was not significantly reduced by alpha IR-3, indicating that IGF-I was not an autocrine mediator of oestradiol stimulation of cell growth under these conditions, whereas alpha IR-3 extensively reduced growth stimulation by IGF-I. On long term stimulation (5 days) oestradiol had a marked stimulatory effect on cell number and alpha IR-3 almost totally abrogated this effect. When oestradiol (1 nM) and IGF-I (2.5 nM) were added together, the combined effect on thymidine incorporation and cell number was significantly greater than additive. This synergistic effect on the IGF-I growth response was totally abolished by the IGF-I receptor antibody. The results suggest a cooperative interaction of oestradiol and IGF-I. It is concluded that growth stimulation of MCF-7 cells by long term treatment with oestradiol may be mediated through autocrine secretion of IGF-I. the effect of short term stimulation of thymidine incorporation suggest that the growth response of oestradiol is more complex, and indicate that a cooperative interaction with IGF-I is involved, which is unrelated to stimulated autocrine secretion.

Concentration of endogenous oestradiol as related to oestradiol receptor sites in breast tumor cytosol

Biopsies or mastectomy specimens from 69 malignant and 17 non-malignant human breast tumours have been examined with respect to cytoplasmic oestradiol receptors and endogenous oestradiol concentration. Of the malignant tumours, 45 (65%) had significant oestradiol receptor concentrations (136.7 fmol/mg protein +/- 38.3 S.E.M.). Oestradiol values in the cytosol were not correlated to receptor levels. Cytosol oestradiol concentrations in the receptor-negative tumours were normally distributed about a mean value of 7.4 fmol/mg protein +/- 0.9 (S.E.M.). Oestradiol levels were similar to the median concentration of receptor found in tumours from younger women, and consequently may influence receptor measurements in such tumours. In receptor-positive cytosols a much wider range (less than 1 to 69.7 fmol/mg protein) and a non-symmetrical distribution of oestradiol values were found which closely corresponded to the range of occupied receptor concentrations previously measured in tumour cytosol. When tumours having undetectable oestradiol values were excluded, receptor-positive cytosols had significantly higher oestradiol concentrations than those found in receptor-negative tumours (P less than 0.01). No significant difference in cytosol oestradiol concentration was found in receptor-positive and negative pre- and postmenopausal women. This would indicate that factors other than plasma levels influence tissue availability of oestradiol.

Alterations in the Metabolism of Oestrogens During Treatment with Aminoglutethimide in Breast Cancer Patients

SummaryIn this small study, the effect of aminoglutethimide on the disposition of oestrogens in women with advanced breast cancer was investigated using bolus injections of 4-[14C]-oestradiol and 6,7-[3H]-oestrone sulphate, alone or in combination.No alterations in oestrogen disposition were seen after short term (6 hours) aminoglutethimide administration. During long term (3 weeks to 8 months) aminoglutethimide treatment mean 4-[14C]-oestradiol clearance was not changed. 14C-Oestrone sulphate AUC was reduced by 43% at a low dose of aminoglutethimide (125mg twice daily) and by 65% at a high dose (250mg 4 times daily) with hydrocortisone acetate 25mg twice daily. The oestrone sulphate terminal elimination rate constant (λz) was concurrently increased (mean of 46 and 79%, respectively, with the 2 dosage regimens).A possible increase in oestrone sulphate clearance during long term treatment was tested for by injecting 6,7-[3H]-oestrone sulphate. These studies revealed a marked increase (mean 104%) in oestrone sulphate clearance in patients receiving the high dose aminoglutethimide schedule.Following injection of 4-[14C]-oestradiol plus 6,7-[3H]-oestrone sulphate, the fraction of 4-[14C]-oestradiol metabolised to oestrone sulphate was found to be reduced in all patients (mean 13%). A mean increase of 80% in the urinary excretion of 14C-oestriol was observed after 4-[14C]-oestradiol administration.Our results, although preliminary, suggest that aminoglutethimide is a potent inducer of aminoglutethimide metabolism, thereby producing a significant reduction in plasma bioavailability of oestrone sulphate. These effects may have a role in the action of aminoglutethimide, a finding which warrants further investigation.

Separation of urinary metabolites of radiolabelled estrogens in man by HPLC

A method to separate radiolabelled urinary estrogens by high performance liquid chromatography (HPLC) is described. Estrogen glucuronides were isolated from the urine of women receiving bolus injections of [4-14C]estrone or [4-14C]estradiol by adsorption on Sep-Pak C18 cartridges and subsequent DEAE Sephadex A25 column chromatography. Following enzyme hydrolysis, free estrogens were extracted and concentrated in methanol-water containing ascorbic acid. HPLC was performed either by C18 reversed phase chromatography using different concentrations of acetonitrile with or without tetrahydrofurane in phosphate buffer or methanol-water as mobile phases, or on a Diol column using chloroform-isooctane-n-hexane or isopropanol-isooctane-n-hexane as mobile phases. 3H-labelled estrogens were added as internal standards, and urinary [14C]estriol, [14C]estradiol and [14C]estrone concentrations could be measured with an interassay coefficient of variation less than 5%. Interassay coefficients of variation for [14C]2-hydroxyestriol, [14C]16 alpha-hydroxyestrone, [14C]2-hydroxyestradiol, [14C]2-hydroxyestrone and [14C]2-methoxyestrone were between 5 and 10%, while interassay coefficients of variation for [14C]4-hydroxyestrone was 14.6%. Recovery of the unstable catechol estrogen 2-hydroxyestrone was comparable to the recovery of the other estrogen metabolites, due to the addition of ascorbic acid throughout the different pre-chromatographic steps. Our method is suitable for the separation of the major labelled estrogen metabolites found in human urine following administration of radiolabelled estrone or estradiol.

The Effect of the Stimulant Drugs, Dextroamphetamine and Methylphenidate, on Secretion of Growth Hormone in Hyperactive Children.

The stimulant effect of L-dopa (125 to 500 mg) was compared to dextroamphetamine and methylphenidate, 15, and 20 mg, respectively, on growth hormone secretion in 20 hyperactive children. All three stimulants were responsible for peak GH concentration in serum at 60 minutes after drug ingestion; there was no significant difference between the mean GH level at any time of sampling. Seven of the children were retested with L-dopa and dextroamphetamine after six to eight months of treatment with methylphenidate. After treatment, there was a tendency to higher zero time levels of GH, and to delayed and/or paradoxical response to dextroamphetamine. The findings indicate an acute and a probably long-term effect of dextroamphetamine and methylphenidate on the homeostasis of growth hormone. The possible long-term adverse effects of these drugs on the growth of children indicates the need for caution to the widespread use of these agents.

The associations of obesity, lymph node status and prognosis in breast cancer patients: Dependence on estrogen and progesterone receptor status

Breast cancer patients who are obese have a higher risk of lymph node metastases and a poorer prognosis than those who are slim. It has been claimed that estrogens derived from fat are important for these associations. If estrogens are important, these relationships must be stronger in the hormone receptor‐positive than in the hormone receptor‐negative groups. Body mass index (BMI) was used as a measure of obesity. The second, third, and fourth quintiles of BMI were treated as one group and termed ‘medium’. Patients in the fifth quintile were termed ‘obese’ and those in the first quintile ‘slim’. The number of women with unilateral disease treated with modified radical mastectomy and included in the study was 1211. Of all patients included, obese patients had a 1.53 higher risk of lymph node metastases compared to slim patients (p=0.02). In the PgR‐negative group, obesity gave a 3.08 times higher risk of lymph node metastases (p=0.03). The risk of dying of breast cancer tended to be higher in obese than in slim patients when all patients in the study were compared (relative risk=1.38, p=0.06). BMI did not show a statistically significant relationship with prognosis if only hormone receptor status was considered. However, if lymph node status and hormone receptor status were taken together, the association was strong and reversed in the lymph node‐positive group with ER‐negative tumours. The adjusted relative risk was 0.33, showing that slim patients had a 3.03 (1.0/0.33) times higher risk of dying of breast cancer compared to obese patients (p=0.002). These results indicate that non‐hormonal mechanisms could be important.

Eicosapentaenoic acid and sulphur substituted fatty acid analogues inhibit the proliferation of human breast cancer cells in culture

Numerous studies have shown dietary fatty acids toinfluence the progression of several types of cancers.The purpose of the present investigation was toexamine the influence of various types of fattyacids, including ω-3 fatty acids and a newclass of hypolipidemic peroxisome proliferating fatty acid analogues,namely the 3-thia fatty acids, on MCF-7 humanbreast cancer cell growth. 3-thia fatty acids representnon-β-oxidizable fatty acid analogues in which a sulphuratom substitutes for the β-methylene group (3-position) inthe saturated and unsaturated fatty acids.The effects of increasing concentrations of palmitic acid,tetradecylthioacetic acid (a 3-thia fatty acid), eicosapentaenoic acid,docosahexaenoic acid, and two 3-thia polyunsaturated fatty acidson the proliferation of MCF-7 cells, maintained inserum-free culture, were studied. At the highest concentrationof fatty acid used (64 µM) tetradecylthioacetic acidwas found to be the most effective ofall fatty acids tested in inhibiting cell growth,whilst palmitic acid and docosahexaenoic acid had nosignificant effect on cell growth. Thus, of thetwo dietary polyunsaturated ω-3 fatty acids eicosapentaenoic acidand docosahexaenoic acid, only eicosapentaenoic acid possesses aninhibitory effect on the proliferation of MCF-7 cells.In all cases the inhibitory effect of thefatty acid was found to be reversible.Tetradecylthioacetic acid has been shown to be apotent peroxisome proliferator. It was, therefore, hypothesized thattetradecylthioacetic acid may inhibit the human MCF-7 cellgrowth by increasing the level of oxidative stresswithin the cell. However, use of agents whichmodify the cells protective apparatus against oxidative stresshad no influence on the inhibitory effect oftetradecylthioacetic acid.These experiments indicate that tetradecylthioacetic acid inhibits cellgrowth by mechanisms which may be independent ofoxidative status.

Effects of aminoglutethimide on plasma estrone sulfate not caused by aromatase inhibition

Plasma levels of estrone and estrone sulfate were measured in 16 postmenopausal women with advanced breast cancer before and during chronic aminoglutethimide therapy. Aminoglutethimide caused a significant reduction in plasma estrone (mean 36%, P less than 0.025) and estrone sulfate (mean 65%, P less than 0.001). The estrone/estrone sulfate ratio was increased by a mean of 84% (P less than 0.0025). These results suggest that aminoglutethimide influences plasma estrone sulfate by mechanisms unrelated to aromatase inhibition. The findings in this study are consistent with previous results suggesting that aminoglutethimide treatment enhances the rate of estrone sulfate metabolism. This biochemical effect of aminoglutethimide treatment could be a contributory factor to the drugs mechanism of action.