Secretion of bioactive interleukin 1 by rat testicular macrophages in vitro

The relative capacities for testicular macrophages and resident peritoneal macrophages to secrete the pro-inflammatory cytokine, interleukin 1 (LL-1), in response to stimulation by bacterial lipopolysaccharide (LPS), were compared in vitro. Macrophages were isolated from adult male rat testicular interstitial cells or peritoneal lavage by adherence to glass coverslips or plastic culture dishes. The macrophages were immediately cultured, with or without a maximal dose of LPS (1 mu g/ml), over 24 hours at 32 degrees Celsius. Bioactive LL-1 production was measured by a sensitive thymocyte proliferation bioassay, employing recombinant human LL-1 beta as the reference standard. In comparison with the peritoneal macrophages, testicular macrophages displayed only a very small response to LPS, producing 2.8% of the amount of LL-1 per cell secreted by peritoneal macrophages cultured under identical conditions. Production of authentic LL-1 was confirmed by inhibition of the bioassay response in the presence of human recombinant LL-1 receptor antagonist. A small molecular mass (<10 kDa based on ultrafiltration) inhibitor of LL-1 bioactivity was also present in the medium collected from both cultures, but this inhibitory activity did not account for the differences in activity observed. In cultures of total peritoneal cells under similar conditions, addition of testosterone (10-1,000 ng/ml) did not affect LL-1 production in response to LPS. These data indicate that testicular macrophages have a reduced ability to secrete bioactive IL-1, and they provide further evidence for an altered capacity for immune responses within the testis.

Role of growth factors, steroid and peptide hormones in the regulation of human prostatic tumor growth

Previous work carried out in the authors' laboratory has shown that LHRH agonists directly inhibit the proliferation of hormone-responsive and hormone-independent human prostatic cancer cell lines (respectively LNCaP and DU145). In addition, the hormone-dependent LNCaP cells respond to a challenge with testosterone with an increase in growth rate. The following experiments have been performed to investigate whether the LHRH agonists might act by interfering with the stimulatory actions of either the EGF/TGF alpha system or androgens. The results obtained in LNCaP and DU145 cells show that LHRH agonists counteract the mitogenic action of the EGF/TGF alpha system. This effect is mediated by a decrease in the concentration of EGF receptors. In addition, in the hormone-dependent LNCaP cells, the treatment with LHRH agonists antagonizes the proliferation promoting effect of testosterone, which in turn appears to be mediated by the activation of the locally expressed EGF/TGF alpha system. Finally, the results suggest the presence in LNCaP cells of a soluble peptidase able to degrade LHRH. In conclusion, the present data suggest an intimate interplay among the actions of LHRH agonists, of androgens and of growth factors, thus, supporting the hypothesis that LHRH agonists may interfere with the EGF/TGF alpha stimulatory loop and with androgens in the control of the proliferation of human prostatic tumors.

Octreotide therapy in carcinoid disease

Octreotide therapy is expensive, but at present it and other somatostatin analogues appear to offer the best opportunity of controlling the symptoms of flushing and diarrhoea. It may also have other properties affecting general well-being. The question of whether it changes tumour growth remains unanswered and there is no convincing evidence that it alters survival. In all published studies the numbers of patients are small and there have been no control groups. However, since no other drug has yet proved effective against flushing, the somatostatin analogues, including octreotide, remain the treatment of choice for the symptomatic control of the carcinoid syndrome. Octreotide is of great therapeutic value pre-operatively and intra-operatively and it is essential that all operating theatres have this drug available for immediate use. Surgical debulking, if feasible, provides the best outcome potential in carcinoid disease. Present evidence suggests that the place of octreotide and other somatostatin analogues is in controlling the symptoms of the disease rather than its progress and in ensuring cardiovascular and respiratory stability during surgical procedures.

P450-dependent enzymes as targets for prostate cancer therapy

Metastatic prostate adenocarcinoma is a leading cause of cancer-related deaths among men. First line treatment is primarily aimed at blocking the synthesis and action of androgens. As primary endocrine treatment, androgen deprivation is usually achieved by orchidectomy or LHRH analogues, frequently combined with androgen receptor antagonists in order to block the residual adrenal androgens. However, nearly all the patients will eventually relapse. Available or potential second line therapies include, among others, alternative endocrine manipulations and chemotherapy. Cytochrome P450-dependent enzymes are involved in the synthesis and/or degradation of many endogenous compounds, such as steroids and retinoic acid. Some of these enzymes represent suitable targets for the treatment of prostate cancer. In first line therapy, inhibitors of the P450-dependent 17,20-lyase may achieve a maximal androgen ablation with a single drug treatment. Ketoconazole at high dose blocks both testicular and adrenal androgen biosynthesis but its side-effects, mainly gastric discomfort, limit its widespread use. A series of newly synthesized, more selective, steroidal 17,20-lyase inhibitors related to 17-(3-pyridyl)androsta-5,16-dien-3beta-ol, may open new perspectives in this field. In prostate cancer patients who relapse after surgical or medical castration, therapies aiming at suppressing the remaining adrenal androgen biosynthesis (ketoconazole) or producing a medical adrenalectomy (aminoglutethimide+hydrocortisone) have been used, but are becoming obsolete with the generalization of maximal androgen blockade in first line treatment. The role of inhibition of aromatase in prostate cancer therapy, which was postulated for aminoglutethimide, could not be confirmed by the use of more selective aromatase inhibitors, such as formestane. An alternative approach is represented by liarozole fumarate (LIA), a compound that blocks the P450-dependent catabolism of retinoic acid (RA). In vitro, it enhances the antiproliferative and differentiation effects of RA in cell lines that express RA metabolism, such as F9 teratocarcinoma and MCF-7 breast carcinoma cells. In vivo, monotherapy with LIA increases RA plasma levels and, to a greater extent, endogenous tissue RA levels leading to retinoid-mimetic effects. In the rat Dunning prostate cancer models, it inhibits the growth of androgen-independent as well as androgen-dependent carcinomas relapsing after castration. Concurrently, changes in the pattern of cytokeratins characteristic of increased differentiation were observed. Early clinical trials show that LIA, in second or third line therapy in metastatic prostate cancer, induces PSA responses in about 30% of unselected patients. In some patients regression of soft tissue metastasis ha been observed. In a subgroup of patients, an important relief of metastatic bone pain was also noted.

Novel endocrine therapies in breast cancer

Endocrine therapy of breast cancer consists of a variety of both medical and surgical ablative treatment modalities, but ablative therapy is increasingly replaced by medical treatment. Most endocrine therapies have more than one endocrine effect, frequently together with direct growth inhibitory actions via receptors. Endocrine therapy can be effective in all phases of the disease, but curative only in early disease while in advanced cancer it can only prolong survival. In the past decade the number of available endocrine agents has been drastically increased. Novel approaches in the endocrine therapy of breast cancer are application of new antiestrogens, antiprogestins, new potent aromatase inhibitors, analogues of luteinizing hormone-releasing hormone (LHRH-A) and somatostatin, inhibitors of prolactin secretion, vitamin A and D analogues, bisphosphonates, growth factor antagonists, tyrosine protein kinase inhibitors, protease inhibitors, inhibitors of angiogenesis, radiolabeled hormones and monoclonal antibodies. New cell biological factors such as oncogenes and suppressorgenes, secretory proteins and membrane receptors can be used not only as prognostic factors but also for prediction of type of response to endocrine and chemotherapy. Thus, these cell biological parameters can be used to select high and low risk patients, type of systemic treatment, and can also be used as targets for new treatment modalities. Future studies on treatment of all stages of disease will increasingly focus on promising combined treatment modalities.

Changes in radiation sensitivity and steroid receptor content induced by hormonal agents and ionizing radiation in breast cancer cells in vitro

Possible influences of tamoxifen and estradiol on in vitro radiation sensitivity and cellular receptor content after irradiation and/or tamoxifen treatment were studied in breast cancer cell lines; estrogen receptor (ER) and progesterone receptor (PgR) positive cell lines MCF-7 and MCF-7/TAM(R)-1 and the ER and PgR negative cell line MDA-MB-231. The tamoxifen resistant MCF-7/TAM(R)-1 cells were more resistant to ionizing radiation than the MCF-7 and MDA-MB-231 cells. Exposure to tamoxifen made the MCF-7 cells more radiation resistant, while estradiol made the MDA-MB-231 cells more radiation sensitive. A radiation dose of 6 Gy reduced the ER content in cytosol in both MCF-7 and MCF-7/TAM(R)-1 cells, but brought no alterations to the PgR content. In MCF-7/TAM(R)-1 cells tamoxifen exposure significantly increased the ER and reduced the PgR content, an effect not observed in the MCF-7 cells. To conclude, the present study indicates that irradiation and tamoxifen may modify the ER and PgR content in cytosol in breast cancer cells. Hormonal treatment may alter the radiation sensitivity, even in ER negative cells, suggesting that hormonal agents may act both via receptor and non-receptor binding mechanisms.

Angiogenic response of MCF7 human breast cancer to hormonal treatment: assessment by dynamic GdDTPA-enhanced MRI at high spatial resolution

Dynamic gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced MRI was followed during growth and regression of MCF7 human breast tumors implanted in nude mice in the presence of estrogen and tamoxifen, respectively. Gradient-echo and spin-echo sequences were applied at a temporal resolution of 12 and 100 seconds, respectively, and a spatial resolution of 195 x 390 x 1000 microns. Maps of initial rates of contrast enhancement demonstrated stimulation of local growth of permeable microcapillaries at regions bordering necrotic areas, resulting from tamoxifen treatment. This localized angiogenic stimulation was confirmed by immunohistochemical staining of endothelial cells. After 1 week of tamoxifen treatment, the fraction of tumor pixels exhibiting rapid initial rate of contrast enhancement increased significantly from .28 +/- .05 to .46 +/- .06. In parallel, the fraction of tumor area showing contrast enhancement 3 minutes after Gd-DTPA injection also increased significantly, from .42 +/- .06 to .58 +/- .06. On the basis of these changes, it was possible to assess the response to tamoxifen therapy at an early stage.

Octreotide in malignant intestinal obstruction

Octreotide has proved an effective agent in the palliation of refractory malignant intestinal obstruction. This may be achieved through a pro-absorptive effect on the small bowel mucosa, an effect on improving gastrointestinal motility, by a reduction in gastrointestinal hormone levels and by a direct anti-neoplastic effect on the obstructing tumour. The simple route of administration of octreotide and the paucity of side effects reported in two recent studies should make the physician consider its use in this particularly distressing complication of advanced cancer.

Therapeutic potential of octreotide in the treatment of liver metastases

Octreotide is a synthetic analogue of somatostatin that has clear inhibitory effects on the growth of many animal and human cell lines, including colorectal cell lines both in vitro and in vivo. Colorectal cancer metastatic to the liver is clinically important, both in terms of the number of patients affected and the lack of any effective treatment for the majority of patients. Octreotide inhibits the growth of colorectal liver tumour in a number of experimental models and, in at least three tumour types, inhibits the growth of established micro-metastases. The precise mechanism of action is not known. However, the drug is likely to be most beneficial in the treatment of liver metastases when the tumour burden is relatively small. The available evidence, although experimental, suggests that octreotide may also have a beneficial effect on the development of liver metastases when used as an adjuvant to surgery in colorectal cancer and this area warrants urgent clinical investigation. The cytotoxics which are currently used as an adjuvant to surgery for colorectal cancer have unpleasant side effects which can be life-threatening. There will also be a proportion of patients who have undergone a truly curative resection of their tumour and will thus be treated unnecessarily. The potential benefits of octreotide in the adjuvant setting, although promising, remain speculative, but octreotide has an acceptably low incidence of side effects and can be administered safely for a prolonged period of time.

Mechanisms of tamoxifen resistance in the treatment of advanced breast cancer

Multiple mechanisms may render breast cancer cells resistant to treatment with the antiestrogen tamoxifen. This review describes changes in the estrogen receptor (ER) signaling pathway which may lead to tamoxifen resistance: change in uptake or metabolism of tamoxifen, loss of expression of ER, decreased expression of ER, expression of mutant or variant forms of ER, intact ER but loss of cofactors, ligand-independent ER activation, modification of the estrogen response element, altered post-receptor events. Non-ER related alterations are also mentioned.

The nuclear channel system in endometrial adenocarcinoma exposed to medroxyprogesterone acetate

The nuclear channel system (NCS), giant mitochondria and subnuclear glycogen form a triad of ultrastructural features observed in normal human endometrial epithelium in response to progestational steroids. Both the giant mitochondria and subnuclear glycogen have been described in endometrial adenocarcinoma, but the NCS has not. This article reports the development of the NCS in adenocarcinoma treated with medroxyprogesterone acetate. Previous studies suggest that the NCS in normal tissue is a response to the acyl group in the 17-beta position of the D-ring of some progestational steroids, such as medroxyprogesterone acetate. Medroxyprogesterone acetate was administered to 12 postmenopausal women with endometrial adenocarcinoma. Hysterectomies were performed 8 to 20 days after treatment. Pretreatment specimens were also obtained on 8 of the 12 patients. Using standard electron microscopy procedures, light microscopy on plastic semithin sections was first used to confirm the presence of tumor. Thin sections of malignant endometrium were prepared and evaluated ultrastructurally for progestational alterations. Abnormal giant mitochondria and subnuclear glycogen were found both before and after treatment. The third element of the triad, the NCS, was not observed in any of the available pretreatment biopsies, but was seen in three of the treated specimens. Thus it appears that the NCS is a response to the given progesterone therapy.

Tamoxifen metabolic activation: comparison of DNA adducts formed by microsomal and chemical activation of tamoxifen and 4-hydroxytamoxifen with DNA adducts formed in vivo

One of our laboratories recently showed by 32P-postlabeling that administration of tamoxifen to mice induces two groups of hepatic DNA adducts comprising two major spots, nos. 3 and 5, respectively. 4-Hydroxytamoxifen and alpha-hydroxytamoxifen appear to be the proximate metabolites of groups I and II adducts, respectively. The relative significance of these two adduct groups for tamoxifen carcinogenicity remains to be established. To determine the activation mechanism(s) of tamoxifen and 4-hydroxytamoxifen, in vivo adducts were compared by 32P-postlabeling with adducts generated by microsomal or chemical activation in vitro. Microsomal activation of 4-hydroxytamoxifen and tamoxifen, respectively, in the presence of DNA and cumene hydroperoxide, induced two adducts, which mapped similarly to the corresponding in vivo adduct spots 3 and 5. Chemical oxidation of 4-hydroxytamoxifen with silver(II) oxide, followed by incubation of the product(s) with DNA, elicited the formation of a major spot (Q1), while tamoxifen itself did not react. Rechromatographic analyses revealed that in vitro fractions 3 and Q1 (from 4-hydroxytamoxifen) matched the major in vivo group I adduct fraction 3, consistent with the hypothesis that 4-hydroxytamoxifen is a precursor for adduct fraction 3 in vivo. The in vitro adduct fraction 5 (from tamoxifen) was identical to that formed in vivo, indicating that the metabolic pathway for the formation of group II adducts did not involve 4-hydroxytamoxifen. In conclusion, the results support a model where primary metabolites of tamoxifen undergo secondary metabolism to form DNA adducts, which are detected in vivo after treatment with tamoxifen or 4-hydroxytamoxifen.

Supportive care is not the only option in prostate cancer patients resistant to hormone therapy: the argument for

In multivariable analyses conducted by several groups, a post-therapy decline in prostate specific antigen was the most significant factor associated with survival of patients with relapsed prostate cancer. Contemporary combination regimens result in consistent declines in prostate-specific antigen in up to 40% of cases, along with objective tumour regression, and the improvement in cancer-related symptoms. It is, therefore, apparent that prostate cancers are not as resistant to treatment as previously believed.

Supportive care is not the only option in prostate cancer patients resistant to hormone therapy: the argument against

Hormone-resistant prostate cancer patients are elderly, frail and in pain. They have a median survival of 6 months. There is no convincing evidence from controlled trials that anything we do will increase life expectancy. Any attempt to do so with currently available agents may either kill them earlier or decrease the quality of the short life left to them. The alternatives for management include the simple, non-toxic, supportive measures of better analgesic use, antiandrogen withdrawal, external beam radiation and steroids, which can produce significant symptomatic improvement. There is little evidence that the benefits of more aggressive therapy exceed those achieved with supportive care.

Potentiation of the anti-proliferative effects of anti-cancer drugs by octreotide in vitro and in vivo

The somatostatin analogue octreotide (SMS 201-995) exerts potent anti-proliferative effects in a number of experimental cancer models. Here we report on the inhibitory effect of octreotide in combination with the chemotherapeutic agents mitomycin C, doxorubicin, 5-fluorouracil, or taxol on the growth of AR42J pancreatic cancer cells in vitro. The dose-dependent anti-proliferative effects of mitomycin C, doxorubicin and taxol were synergistically enhanced by octreotide. Combinations of octreotide and 5-fluorouracil resulted either in additive or, at high concentrations of the chemotherapeutic agent, in synergistic interactions. Combined treatment with doxorubicin and octreotide was also studied for time dependency and potential efficacy in tumour-bearing animals. Pretreatment (24 h) with doxorubicin resulted in clear synergy. However, pretreatment with octreotide 24 h prior to addition of doxorubicin resulted only in an additive interaction. It was shown in AR42J-tumour-bearing nude mice that the combination of doxorubicin and octreotide was well tolerated. Tumour growth was inhibited to 9% of controls, compared with 44% in the doxorubicin alone arm (day 14 of treatment). Our in vitro and in vivo interaction studies suggest that octreotide potentiates the effect of various chemotherapeutic agents in a synergistic or additive manner.

Enhancement of the anti-neoplastic effects of tamoxifen by somatostatin analogues

Tamoxifen is useful in the treatment of breast cancer, but its effects in metastatic disease are rarely long term, and development of resistance to the drug is common. In vitro and in vivo data demonstrate anti-neoplastic (anti-proliferative) effects of somatostatin analogues, which may occur via binding to somatostatin receptors on the neoplastic cells, and/or via reductions in insulin-like growth factor-1 bioactivity. Moreover, several lines of evidence from in vitro and in vivo studies indicate that the long-acting somatostatin analogue octreotide enhances the anti-neoplastic effects of anti-oestrogenic agents such as tamoxifen. The anti-oestrogen-somatostatin approach appears to have a favourable long-term toxicity profile. Large-scale clinical trials are currently being planned to investigate the efficacy of combined tamoxifen plus octreotide therapy compared to tamoxifen alone in patients with breast cancer.

[The reversing effect of HPV-16 E6E7 gene antisense plasmid on the HPV-16 positive human cervical carcinoma cells]

Antisense reconstruct, p16as E6E7Neo, harboring HPV-16E6E7 gene of which the expression is regulatable by dexamethasone was constructed. Calcium phosphate mediated transfection was employed to transduce this antisense reconstruct into HPV-16 positive CasKi cell line and HPV negative C-33A cell line (both derived from human cervical carcinoma) respectively. After dexamethasone was added into the culture medium to induce the expression of E6E7 antisense gene, the malignity of CasKi cells were reversed, while the growth characteristics and malignity of C-33A cells were unchanged. The results show that the reversing effect on CasKi cell is specific and mediated by inhibition of expression of E6E7 gene. It also demonstrated a more profound pathogenic role of HPV-16 E6E7 gene in the tumorogenesis of cervical carcinoma and provides a possibility for gene therapy of this tumor.

Relationship between tamoxifen-induced transforming growth factor beta 1 expression, cytostasis and apoptosis in human breast cancer cells

Previously we have shown that tamoxifen (TAM) induces morphological and biochemical changes typical of apoptosis in oestrogen receptor (ER)-positive MCF-7 or ER-negative MDA-231 human breast cancer cells. In this study the effects of TAM on expression of transforming growth factor beta 1 (TGF-beta 1) were correlated with the effects on cell cycle kinetics and apoptosis. TAM had similar biphasic effects on both cell lines. Short-term (< 6 h) TAM incubation resulted in a slight decrease in TGF-beta 1 protein despite an increase in TGF-beta 1 mRNA and was associated with an increase in cells in S-phase. No apoptotic effects were noted. Longer (> or = 12 h) TAM incubation induced TGF-beta 1 protein (about 3-fold) and mRNA expression (about 2-fold) in both cell lines, and was associated with G1/G0 blockade and induction of apoptosis. The accumulation of TAM-induced TGF-beta 1 mRNA was increased by cycloheximide, but was not affected by 17 beta-oestradiol. Long-term incubation with TAM had no significant effect on TGF-beta 1 gene copy number. TAM-induced internucleosomal DNA cleavage was inhibited in both cell lines by the addition of an anti-TGF-beta 1 antibody. TAM has dose- and time-dependent effects on TGF-beta 1 expression associated with changes in cell cycle kinetics. These effects are independent of ER status and may be the result of a direct regulatory effect of TAM on TGF-beta 1 transcription. It also appears that induction of TGF-beta 1 plays an important role in TAM-induced apoptosis in breast cancer cells.

Tamoxifen inhibits hepatoma cell growth through an estrogen receptor independent mechanism

BACKGROUND/AIMS

Tamoxifen has previously been shown to prolong the survival of patients with advanced stages of hepatocellular carcinoma and it has been suggested that it inhibits the growth of hepatoma cells through an estrogen receptor-dependent mechanism. We have studied the effects of the synthetic estrogen, mestranol, and the antiestrogen, tamoxifen, on the growth regulation of hepatoma cells in vitro.

METHODS

Cells were maintained under fully estrogenized conditions and were deprived of estrogen shortly before conducting experiments.

RESULTS

In the human hepatoma cell line Hep 3B, tamoxifen inhibited cell growth in a concentration and time-dependent manner with effective concentrations ranging from 0.1 microM to 10 microM. Mestranol inhibited cell growth at a concentration of 10 microM and had an additive effect with tamoxifen on growth inhibition. Expression of estrogen receptors in hepatoma cells was not detected by enzyme immunoassay, Northern blot analysis or reporter gene expression assay. Furthermore, the introduction of estrogen receptors into Hep 3B cells did not alter the effect of tamoxifen and mestranol on cell growth.

CONCLUSIONS

This study suggests that tamoxifen inhibits the growth of Hep 3B hepatoma cells through an estrogen receptor-independent mechanism.

Evaluation of prostate-specific antigen as a surrogate marker for response of hormone-refractory prostate cancer to suramin therapy

PURPOSE

We evaluated the surrogate role of serum prostate-specific antigen (PSA) using prospectively collected information from patients with hormone-refractory prostate cancer (HRPC) treated with suramin.

MATERIALS AND METHODS

Data from 103 patients were analyzed using survival analysis, exploratory analysis, and regression analysis.

RESULTS

There was a significant survival difference between groups of patients with a PSA decrease of < or = 0% or greater than 0% (P = .018). There were no significant overall survival differences between groups of patients with PSA decreases less than 50% or > or = 50% and less than 75% or > or = 75%. Tree-based modeling did not define a specific threshold percentage PSA change as a response criterion. For a response of 1-year survival, sensitivity increased (0.91 v 0.69), but specificity decreased (0.37 v 0.62), with a 75% versus 50% PSA decrease used as classification criterion. Differences between the area under the receiver-operating curves (ROCs) with 50% and 75% PSA decreases as threshold values were small. For a response of 1-year survival, attributable proportions were 0.38 and 0.68, respectively, with 50% and 75% PSA decreases as threshold values. When pretreatment variables were assessed by Cox proportional hazards model, hemoglobin level was the most significant predictor of survival. When percentage PSA change was included in the model, hemoglobin level remained the most significant factor, but percentage PSA change was also a weak, but statistically significant, factor. PSA was a weak, but statistically significant, predictor of survival in Cox proportional hazards model with PSA as a time-variant covariate.

CONCLUSION

Reduction in PSA level has weak prognostic significance with respect to survival in HRPC patients, but, currently, PSA reduction cannot be used as a reliable response criterion to evaluate treatment efficacy in individual patients. Prospective, randomized studies, including prospective measurement of other indices related to symptomatic clinical benefits, are required.

Comparison between the effects of tamoxifen and toremifene on the uterus in postmenopausal breast cancer patients

Antiestrogens have been widely used in the treatment of breast cancer patients. We wanted to compare the uteral and vaginal effects of tamoxifen to those of toremifene. Thirty-one gynecologically asymptomatic postmenopausal breast cancer patients with an intact uterus were randomized to receive 20 mg of tamoxifen (N = 16) or 60 mg of toremifene (N = 15) as an adjuvant treatment. Gynecological examination with vaginal ultrasonography, Pap smear, endometrial biopsy, hysteroscopy, and curettage was performed before the treatment, and at 6 and 12 months of treatment. Endometrial thickness was found to increase significantly during the treatment to the same extent in both groups. Proliferation or other estrogenic effects in the endometrium were observed in 8 of 14 patients in the tamoxifen group and in 3 of 10 patients in the toremifene group. Three polyps occurred and previously present uterine fibroids increased in size in 3 of 10 patients during the study. Estrogenic changes in Pap smear were observed in all patients. There was no significant difference between tamoxifen and toremifene in any of the parameters investigated. Our results suggest that tamoxifen and toremifene produce comparable estrogenic effects in the uterus and vagina.

The myometrium of postmenopausal women produces prolactin in response to human chorionic gonadotropin and alpha-subunit in vitro

OBJECTIVES

To examine the effect of equimolar concentrations of hCG and dissociated alpha-subunit on PRL production by leiomyoma and myometrial tissue obtained from different hormonal states and to examine changes in PRL messenger RNA levels as PRL protein levels increased.

DESIGN

Explant cultures of leiomyomas and myometrium were established and cultured for 96 hours. Tissue was studied from normal cycling women, postmenopausal women, pregnant women, and women undergoing GnRH agonist (GnRH-a) therapy. Cultured medium was collected at 24, 48, and 96 hours and assayed for PRL. In selected experiments, tissue was processed at 0 and 96 hours to analyze messenger RNA (mRNA) levels.

RESULTS

Human chorionic gonadotropin and alpha-subunit stimulated PRL secretion in [1] explant cultures of leiomyoma and myometrium from premenopausal women, [2] cultures of tissue treated in vivo with leuprolide acetate for both leiomyoma and myometrium, and [3] myometrium obtained from postmenopausal women. Postmenopausal myometrium was significantly more responsive to stimulation. Prolactin mRNA levels were documented to increase after hormone treatment in postmenopausal myometrium.

CONCLUSION

Myometrium from postmenopausal women is very responsive to hCG and alpha-subunit. There is a difference in response between tissue obtained from menopausal women and that from women undergoing GnRH-a therapy to achieve a "medical menopause" and reproductive age women. The level of endogenous gonadotropins as well as the steroid milieu may modulate myometrial PRL secretion.

Influence of cyclopropyl antiestrogens on the cell cycle kinetics of MCF-7 human breast cancer cells

Five cyclopropyl compounds, previously shown to exhibit pure antiestrogenic activity in the mouse uterotropic assay and antiproliferative activity of MCF-7 human breast cancer cells in culture, were examined for their influence on the cell cycle kinetics of MCF-7 cells. The DNA-histogram of a single cell suspension was obtained on Coulter Epics V after fixing the cells in 70 % ethyl alcohol and staining in propidium iodide. Tamoxifen increased the percentage of cells in G1-phase with a concomitant decrease in percentage of cells in S-phase, in an estradiol reversible manner. Cyclopropyl compound 7a increased the percentage of cells in G1-phase, in an estradiol-irreversible manner. Further, compounds 5a, 5c, 7a and 7b decreased the percentage of cells in S-phase and increased percentage of cells in the G2M-phase, in an estradiol-irreversible manner. Of the five cyclopropyl compounds tested, only 4d had no influence on the cytokinetic parameters, even though this compound was found to exhibit antiproliferative activity on MCF-7 cells equal to that of tamoxifen. In conclusion, all of the cyclopropyl compounds, except 4d, altered cell cycle parameters of MCF-7 cells in a manner different than that of tamoxifen. Thus, the results of this study indicate that, although these cyclopropyl compounds are antiestrogenic, they produce antiproliferative activity by a distinct mechanism of action in estrogen receptor positive breast cancer cells.

Dihydrotestosterone affects the growth of hormone-unresponsive breast cancer cells: an indirect action

Cell to cell interaction, which plays a crucial role in breast cancer growth, may be regulated by steroid hormones. This study examined dihydrotestosterone (DHT) effects on the interaction between the steroid receptor positive MCF-7 and the steroid receptor negative MDA-MB-231 breast cancer cell lines. The growth of MDA-MB-231 cells was inhibited by medium conditioned by MCF-7 cells grown in presence of DHT but not by medium conditioned by MCF-7 cells grown in presence of both DHT and the antiandrogen hydroxyflutamide. Trypsin pretreatment of conditioned medium abolished its growth-inhibitory effect on hormone-unresponsive cells. DHT itself did not affect the growth of MDA-MB-231 cells when directly added to their culture medium. Data suggest that DHT stimulates, via the androgen receptor, the androgen-responsive breast cancer cells to produce a peptide factor(s) capable of inhibiting the growth of hormone-unresponsive cells.

Assessment of response to carboplatin in patients with hormone-refractory prostate cancer: a critical analysis of drug activity

The clinical presentation of prostate-hormone refractory tumours in 90% of patients is characterised by sclerotic bone metastasis which is not assessable by classic phase II response criteria. Restriction of investigational study of new agents to the minority of patients, with bidimensionally measurable lesions, assessable by conventional WHO response criteria, has been criticised because such cases may represent a highly selected tumour cell population. To circumvent this problem, a variety of response criteria have been proposed. However, prostate specific antigen (PSA) levels have become an integral component, used singly or in combination with other markers of response evaluation. As a result, different response proportions could also be reported using the same single agent in this category of patients. This study repors a different evaluation of carboplatin activity by using WHO, NPCP modified criteria and PSA post-therapy decline as measures of carboplatin activity. It is suggested that treatment efficacy in this category of patients wold be more correctly measured by the proportion of patients who "fail treatment" after a reasonable number of therapy courses, rather than those achieving a conflicting definition of "objective response". Finally, in hormone refractory prostate cancer PSA post therapy declines may represent a measure of treatment efficacy and can be used as a surrogate end point for clinical phase II trials.

Induction of urinary plasminogen activator by retinoic acid results in increased invasiveness of human prostate cancer cells PC-3

Overproduction of uPA by prostate cancer cells in vivo results in tumor invasiveness and osteoblastic skeletal metastasis due to its mitogenic actions in osteoblasts. In the present study we have examined the effect of several growth factors and steroid hormones on regulating uPA gene expression in the human prostate cancer cell line (PC-3). Treatment of these cells with dexamethasone (Dex) caused a decrease, whereas epidermal growth factor (EGF) and fetal bovine serum (FBS) increased uPA expression in a dose-dependent manner. Trans retinoic acid (RA) also induced uPA mRNA and protein production in a dose-dependent manner (10(-6) to 10(-9) M). This increase was seen as early as 2 hr of treatment until 48 hr. Dex treatment resulted in decreased tumor cells invasiveness, whereas exposure to EGF and RA caused an increase in the invasive capacity of PC-3 cells. These studies should help to better understand the control mechanism of uPA expression in prostate cancer, where uPA has been implicated as a major pathogenetic factor.

Plasma lipids and lipoprotein alterations in tamoxifen-treated breast cancer women in relation to the menopausal status

Plasma lipids and lipoprotein profiles were monitored in 72 postmenopausal and 29 premenopausal breast cancer women who were treated with tamoxifen (20 mg twice a day) for 6 months. The levels of total and free cholesterol and LDL cholesterol were markedly (P < 0.001 for each) decreased in 3 and 6 month tamoxifen-treated postmenopausal women than the baseline values of untreated breast cancer patients. On the contrary, plasma ester cholesterol, triglycerides, VLDL and HDL cholesterol levels were increased significantly in these patients. In the case of premenopausal women the lipid lowering potential of tamoxifen was markedly retarded. These results indicated that tamoxifen - treatment was more beneficial and estrogenic in postmenopausal women's lipids. In premenopausal breast cancer women, tamoxifen was antiestrogenic and less beneficial. Hence, the difference in plasma lipids and lipoprotein content was no greater among those receiving tamoxifen and baseline values of premeno - pausal women. These results indicate that tamoxifen-treatment has a more beneficial effect in postmenopausal women, with a likely reduction in cardiovascular disease, than in premenopausal subjects.

Effect of progestin treatment on estradiol-and growth factor-stimulated breast cancer cell lines

BACKGROUND

Reports about the effects of progestins on cell proliferation are contradictory. We investigated the effect of progesterone, medroxyprogesterone acetate, megestrol acetate, ORG 2058 and the antiprogestin RU 486 on two hormone-dependent cell lines, T47D and MCF-7 (characterized by a different content of PgR). The aim of the study was to understand the eventual ability of progestins to interfere with cell proliferation stimulated by estradiol and various growth factors (TGF-a, IGF-I, IGF-II).

MATERIAL AND METHODS

MCF-7 and T47D cells were maintained in DMEM/F12 medium supplemented with 2% FCS while experiments were carried out in the same culture medium using DCC-stripped FCS.

RESULTS

In the absence of estradiol, all tested progestins generally tended to stimulate cell growth in the T47D cell line, but in the MCF-7 cell line only the highest concentrations (10(-6) M and 10(-7) M) were found to be stimulatory. In contrast, in the presence of 10(-8) M estradiol, progestins tended to inhibit cell growth stimulation in MCF-7 and T47D cell lines. The antiprogestin RU 486 exerted a stimulatory effect similar to that promoted by estradiol itself in MCF-7 cells. Instead, in T47D cells, RU 486 did not modify cell growth in the absence of estradiol, but tended to counteract the estradiol-promoted cell proliferation. In MCF-7 cells, medroxyprogesterone acetate and megestrol acetate were also able to effectively counteract the cell growth induced by TGF-alpha. However, none of these progestins was able to abolish cell proliferation promoted by IGF-I or IGF-II.

CONCLUSION

We therefore concluded that failure to respond to progestin treatment may be due to the very heterogeneous nature of human breast tumors and to the inability of these molecules to interfere with the IGF-R pathway.

The effect of ICI 164384 and beta-interferon on the growth and steroid receptor profile of breast cancer cell lines

We investigated the effect of a concomitant treatment of ICI 164384 and B-interferon (beta-IFN) on the growth of estrogen-receptor-positive (ER+) and estrogen-receptor-negative (ER-) breast cancer cell lines and on their steroid receptor profiles. ICI 164384 reduced cell proliferation not only in ER+ but also in ER- cell lines and completely suppressed the stimulation induced by estradiol (E2) in hormone-sensitive cell lines, MCF7 and T47D. When associated with beta-IFN, ICI 164384 increased the inhibitory effect exerted by the low concentration of beta-IFN. Moreover, ICI 164384, singly or in association with beta-IFN, did not affect ER and PgR concentration in ER- cell lines, whereas in ER+ cell lines we observed an almost total disappearance of ER and PgR. In conclusion, our study seems to indicate that, although beta-IFN is able to control the proliferation of hormone-sensitive and hormone-independent subclones, it does not further improve the antiproliferative activity of ICI 164384. In contrast, the presence of ICI 164384, which does not induce the selection of resistant subclones under the same experimental conditions in which TAM does, may improve the efficacy of low concentration of beta-IFN and prevent the development of a secondary TAM-induced resistance.

Mechanisms of action of endocrine treatment in breast cancer

Endocrine treatment plays an important role in the therapy of breast cancer. While the basic mechanisms are understood, additional mechanisms may be of importance to their action and they may also contribute to the mechanism(s) of acquired resistance. Currently, several novel drugs are entering into clinical trials. Observations of the absence or presence of cross resistance to novel 'pure' steroidal antiestrogens and the non-steroidal tamoxifen may add important information to our understanding of the mechanisms of action of both classes of drugs. Similarly, exploration of different aromatase inhibitors in sequence or concert, as well as the combining of different endocrine treatment options may be warranted. Additionally, alterations in different biochemical parameters such as growth factors should not only be carefully explored in relation to treatment options but should also be followed during the course of treatment to asess alterations over time and in relation to the development of drug resistance.

Glucocorticoid receptors and growth inhibitory effects of dexamethasone in human lung cancer cell lines

Expression of glucocorticoid receptors (GR) and growth effects of dexamethasone and the antiglucocorticoid RU-486 were investigated in six cell lines originating from small cell lung cancer (SCLC) and 13 cell lines from non-small cell lung cancer (NSCLC; four adenocarcinoma, four squamous cell carcinoma, four large cell carcinoma and one mesothelioma). All cell lines contained specific and saturable binding sites for the synthetic glucocorticoid dexamethasone, as determined by whole cell assays and by cytosolic receptor assays. The presence of GRs in the carcinoma cells was confirmed by immunocytochemistry. In NSCLC cell lines, GRs were present in large amounts (37-638 fmol/mg cytosolic protein). In SCLC cell lines, GRs were also detectable but in considerably lower concentrations. Growth inhibitory effects of dexamethasone were seen in the cultures of two squamous cell carcinoma lines (EPLC-32M1 and NCI-H157), one adenocarcinoma line (A-549), one large cell carcinoma cell line (LCLC-97TM1) and the cell line of a mesothelioma (MSTO-211H). All cell lines responsive to dexamethasone had high GR concentrations (> or = 164 fmol/mg cytosolic protein). The antiglucocorticoid RU-486 was virtually inactive when administered alone but was able to block the growth-inhibitory effect of dexamethasone. The results indicate that glucocorticoids may inhibit the progression of individual non-small cell lung carcinoma.

Somatostatin and its cyclic octapeptide analog SMS 201-995 as inhibitors of proliferation of human acute lymphoblastic and acute myeloid leukemia

Somatostatin (SS) is a 14 amino acid peptide which is secreted by the hypothalamus and the pancreatic islets. It expresses antiproliferative activity in various organ systems, experiments have suggested effects of SS on hematopoietic cells. Here we present investigations regarding the effect of SS and its analog SMS 201-995 (SMS) on the in vitro proliferation of acute lymphoblastic leukemia (ALL; n = 7 cases), acute myeloid leukemia (AML; n = 21 cases) and chronic lymphocytic leukemia (CLL; n = 2 cases). Both SS and SMS inhibited spontaneous leukemic cell growth in approximately 1/3 of cases (i.e. 7/19). G-CSF stimulated AML cells were inhibited by SMS in 11/21 cases. AML cell proliferation induced by IL-3 or GM-CSF was suppressed in only 3/21 and 6/21 cases, respectively. In ALL cells, IL-7-induced proliferation was suppressed by SMS in 3/7 cases. The effect of SMS seemed to depend on the type of the hematopoietic growth factor, and on their concentrations. In fact, high concentrations of G-CSF could override SMS blocking completely. Colony formation by normal marrow progenitors and DNA synthesis by HL-60 and T11/65 leukemic cell lines were not affected by SMS. In conclusion, somatostatin may act as a negative regulator of the proliferative activity of human leukemia.

Successful in vitro purging of leukemic blasts from marrow by cortivazol, a pyrazolosteroid: a preclinical study for autologous transplantation in acute lymphoblastic leukemia and non-Hodgkin's lymphoma

An important new approach to curative treatment of leukemia is vigorous treatment of autologous marrow to remove residual abnormal cells in vitro prior to reinfusion. This in vitro 'purging' must destroy the malignant cells while preserving sufficient normal precursors to allow re-establishment of normal in vivo function. We have confirmed that cortivazol (CVZ), a glucocorticoid with an unusual structure, can kill dexamethasone (DEX)-resistant leukemic cells and have examined its ability to purge DEX-sensitive (CEM-C7) and -resistant (ICR-27) human leukemic blasts artificially mixed with normal marrow mononuclear cells in vitro. By carefully defining time and dose, we established a 'therapeutic window' that allowed 'cure' of the artificial remission marrow. A sufficient number of viable normal myeloid precursor cells (CFU-GM) remained to suggest that normal marrow precursors adequate for successful marrow transplantation could survive such treatment. CVZ could be a useful drug for in vitro purging of bone marrow for autologous transplantation in patients with acute lymphoblastic leukemia or non-Hodgkin's lymphoma, sensitive or resistant to standard glucocorticoid.

Tissue-selective actions of estrogen analogs

The biological actions of estrogen analogs have frequently confounded prevailing views regarding the mechanism of estrogen action. Agents originally intended as antifertility drugs are now used clinically to promote ovulation. The early work with antiestrogens as antifertility agents lead to the realization that triphenylethylene antiestrogens suppressed the growth of breast tumors. The subsequent ubiquitous clinical use of tamoxifen for adjuvant breast cancer therapy is a direct result of this research. Basic studies using tamoxifen and related antiestrogens revealed the previously unsuspected tissue selective actions of these compounds. This peculiar property is being taken advantage of to gain new insight into the molecular mechanisms of estrogen action. This property also forms the basis for an exciting new approach to hormone replacement therapy to prevent postmenopausal osteoporosis and cardiovascular disease. The laboratory rat played an integral and essential part in each of these developments. The success of the ovariectomized rat model in predicting the tissue selective effects of tamoxifen in women greatly increases confidence that this animal model will be useful in development of a new generation of estrogen analogs designed specifically for postmenopausal hormone replacement.

[Effect of GnRH analogues on bone density in the vertebral column and the femur]

The objective of this study was to evaluate the effect on vertebral and femural bone density of the gonadotropin-releasing hormone (GnRH) analog administration. The changes in mineral bone density after 6 months discontinuation of the GnRH analog treatment were also measured. Forty-three premenopausal women with regular cycles and suffering from uterine myomatosis have been selected for the study. Twenty-eight women (group A) were treated with Goserelin 3.2 mg given as a depot every 28 days for 6 months. Fifteen women were treated with 10 mg of medroxyprogesterone acetate (MPA) from day 16 to day 25 of each month for 6 months. Vertebral and femural bone density was measured (by Hologic QDR-X 1000) just before the start of the study, at 6 months of treatment and at 12 months (after 6 months of discontinuation treatment). Significant loss of vertebral bone density was demonstrated in women treated with GnRH analog. After six months of treatment discontinuation bone mineral density did not recover the pretreatment values. Bone femural density showed a not significant decrease in the GnRH analog group. In our experience, the treatment with GnRH analog in premenopausal women induces a reduction in lumbar bone density that is not reversible after the treatment withdrawal; for this reason it would be safe to add at the GnRH analog a therapy which can prevent the bone loss.

p53 mutation and tamoxifen resistance in breast cancer

A substantial portion of patients with estrogen receptor-positive breast cancer fail to respond to estrogen depletion or to the antiestrogen tamoxifen. The molecular changes that lead to tamoxifen resistance and estrogen-independent growth are unknown. To test the hypothesis that a p53 mutation could result in tamoxifen resistance and estrogen-independent growth, the MCF-7 cell line was transfected with p53 cDNA which was mutated at codon 179 (histidine to glutamine). MCF-7 is an estrogen receptor-positive, estrogen-dependent, tamoxifen-sensitive cell line with only wild-type p53. The presence of transfected mutant p53 cDNA was verified by the PCR, and overexpression of p53 protein was assessed by Western blotting. Five separate mutant-transfected clones were selected and tested in subsequent growth experiments. In monolayer culture, there was no consistent evidence of estrogen-independent growth or tamoxifen resistance in the mutant transfectants compared with vector-only controls or the parental cell line. In soft agar growth experiments, four of five mutant transfectants remained sensitive to tamoxifen in a dose-dependent manner. In the presence of wild-type p53, mutant 179 p53 protein does not result in estrogen-independent growth or tamoxifen resistance. These results do not exclude the possibility that other p53 mutational types could result in tamoxifen resistance, or that loss of the remaining wild-type allele may be necessary to result in this phenotype.

Effect of octreotide infusion on hepatic and tumour blood flow in two experimental models of liver metastases

OBJECTIVE

To investigate the effects of octreotide infusion on hepatic and tumour blood flow in rats with experimentally induced liver tumours.

DESIGN

Blood flow was determined in tumour-bearing rats using a dual reference microsphere technique before and after intravenous infusion of octreotide.

METHODS

Tumours were induced in syngeneic rats by intraportal injection of K12-Tr and WB2054-M adenocarcinoma cells. Hepatic arterial and portal venous inflow, tumour blood flow and systemic arterial pressure were determined before and after octreotide infusion (0.05 microgram/min).

RESULTS

In rats with K12-Tr tumours there was no change in tumour blood flow, hepatic arterial flow or portal venous inflow after octreotide infusion. In contrast, in rats with WB2054-M tumours, octreotide infusion resulted in a significant reduction in the blood flow to the hepatic tumour (from 0.37 to 0.135 ml/min/g) but had no effect on hepatic artery or portal venous inflow.

CONCLUSION

The reduction in blood flow to tumours derived from WB2054-M cells could, at least in part, explain the inhibitory effect of octreotide on the growth and development of these tumours. However, octreotide had no effect on blood flow to tumours derived from K12-Tr cells, suggesting that the analogue must inhibit tumour growth by other mechanisms.

Corticosteroid resistance is increased in lymphoblasts from adults compared with children: preliminary results of in vitro drug sensitivity study in adults with acute lymphoblastic leukaemia

The prognosis of acute lymphoblastic leukaemia (ALL) in adults is poor compared with children in terms of complete remission (CR) and leukaemia-free survival. In children in vitro resistance of leukaemic cells to various cytotoxic agents is an independent poor prognostic marker, but the relevance of in vitro drug resistance in adults to poor prognosis has not been described. Lymphoblasts from 16 adults and 32 children with ALL at initial presentation were assayed for in vitro drug sensitivity in a short-term culture system using the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) as an indicator of cell viability. The following drugs were tested: prednisolone, daunorubicin, mitozantrone, etoposide, melphalan and 6-thioguanine. At initial presentation, lymphoblasts from adults demonstrated a significantly higher degree of in vitro resistance to prednisolone than those from children (P < 0.01). Glucocorticoid resistance may be a fundamental difference between adult and childhood ALL which may underlie different biological aspects and also explain the difference in prognosis. Lymphoblasts from adults who achieved CR were more sensitive in vitro to prednisolone (P = 0.07), daunorubicin (P < 0.05), mitozantrone (P < 0.01) and melphalan (P < 0.05) than cells from those who did not. The MTT assay can predict response to induction chemotherapy in adults and therefore discriminate between standard- and high-risk patients. The assay, however, is not suitable for selection of the most effective agent for treatment because of in vitro cross-resistance of lymphoblasts to various drugs tested.

1,25 dihydroxyvitamin D and dexamethasone decrease in vivo Walker carcinoma growth, but not parathyroid hormone related protein secretion

Parathyroid hormone related protein (PTHrP) is produced by several breast cancers. 1,25 dihydroxyvitamin D (1,25[OH]2D) and Dexamethasone (DEX) have been shown to decrease PTHrP mRNA expression in several cell lines. We therefore tested the in vivo effect of both steroids on PTHrP secretion and tumor development of the Walker carcinoma (WC). WC cells were injected subcutaneously in Fisher rats which were simultaneously treated with either vehicle, or 1,25(OH)2D (0.5 micrograms/kg/d) or DEX (2 mg/kg/d). After 7 days, tumor weight was significantly decreased in the 2 treated-groups as compared to the control group. Vehicle treated-rats developed hypercalcemia, which was also observed in rats treated with 1,25(OH)2D; by contrast, the plasma calcium was significantly decreased in the DEX-treated group compared to vehicle-treated rats. In a dose-effect experiment, this dose of 1,25(OH)2D induced marked hypercalcemia in rats not implanted with WC, but was required to decrease the tumor weight in implanted rats. In both 1,25(OH)2D and DEX-treated groups, plasma PTHrP levels were significantly decreased, but there was a similar correlation between PTHrP plasma level and tumor weight in the three groups. Indeed, the cytosolic PTHrP content/mg tumor was identical in the 3 groups. By contrast, the PTHrP/Actin mRNA in the tumor was significantly decreased in the 1,25(OH)2D group, comparatively to the vehicle and DEX groups. Our results show that Dexamethasone and 1,25(OH)2D decrease WC tumor development in vivo, but do not change the PTHrP secretion by the remaining tumor although steady state PTHrP mRNA content level is decreased by 1,25(OH)2D.

Inhibitory effect of the somatostatin analogue SMS 201-995 and cytokines on the proliferation of human colon adenocarcinoma cell lines

The activity of the synthetic somatostatin analogue SMS 201-995 was investigated in vitro on the growth of SW480 and SW620 human colon adenocarcinoma cell lines. The inhibition of cell proliferation was significant in SW480 cells (-19.6 +/- 1.4% at SMS 201-995 10-9 M, P < 0.05), but not in SW620 cells (-5.5 +/- 0.8% at SMS 201-995 10-8 M) as compared to untreated cultures. Moreover, SMS 201-995 10-8 M decreased the mitogenic effect of epidermal growth factor (EGF) on the SW480 cell line (-26.6 +/- 3.4% vs. cells exposed to EGF 10 ng ml-1 alone, P < 0.05). The effect of combining SMS 201-995 plus the cytokines interleukin-2 (IL-2) or gamma-interferon (gamma-IFN) on SW480 and SW620 cancer cell growth was also evaluated. The treatment produced a synergistic antiproliferative effect against SW620 cells as compared to untreated cultures, with growth inhibition being -20.2 +/- 1.2 and -19.3 +/- 1.3%, at SMS 201-995 10-8 M plus IL-2 or gamma-IFN 100 IU ml-1, respectively, but did not increase the activity of SMS 201-995 against the SW480 cells. In conclusion, the effect of SMS 201-995 on colon cancer cell growth can be enhanced by its combination with cytokines in SW620 but not in SW480 colon adenocarcinoma cells.

Effect of dietary fat or tamoxifen on the expansion of cells harboring Ha-ras oncogenes in mammary glands from methylnitrosourea-treated rats

Diets containing high levels of fat enhance the formation of methylnitrosourea (MNU)-induced mammary gland adenocarcinomas in rats, while administration of the antiestrogen tamoxifen decreases the incidence of these tumors. It is not known, however, at what stage during tumor development the fat or tamoxifen exert their effects. Here we have used a PCR/liquid hybridization and gel retardation assay to determine the effects of dietary fat and tamoxifen on the growth rate of cells harboring an Ha-ras oncogene in the mammary glands of rats at various times following MNU administration. Glands from animals on a high-fat diet had significantly higher mutant cell fractions than those on a low-fat diet at both 30 and 75 days following MNU treatment. In contrast, there was no difference between the mutant cell fractions of tamoxifen-treated animals and controls at either 30 or 70 days. These results suggest that dietary fat promotes tumor formation early in carcinogenesis by stimulating the growth of cells harboring Ha-ras mutations, while tamoxifen delays the appearance of tumors either by acting as a tumoristatic or tumoricidal agent, or by acting to eliminate or retard the growth of preneoplastic cells just prior to the emergence of tumors.

Octreotide reduces the kinetic index, proliferating cell nuclear antigen-maximum proliferative index, in patients with colorectal cancer

BACKGROUND

Somatostatin has been shown to inhibit in vitro and xenograft growth of human colon cancer. The kinetic index, proliferating cell nuclear antigen (PCNA), has previously been used to measure the effects of manipulation of growth of normal rectal epithelium.

METHODS

Twenty-five patients with distal colorectal cancer were considered for entry in a presurgical study of Sandostatin (Sandoz, East Hanover, NJ) 1 mg every 8 hours. Biopsies were performed pretreatment, during treatment (14 days), and day of surgical resection (2 days off treatment). A control series of 16 patients underwent endoscopic and subsequent surgical biopsy. A kinetic index was created called PCNA-maximum proliferative index (PCNA-MPI), which was reproducible within one biopsy and between two separate biopsies. Multiple biopsies were taken from the growing edge of tumors, the most cellular and best-stained fields selected, and the highest 6 of 10 separate counted fields were used to produce PCNA-MPI.

RESULTS

A significant decline in PCNA-MPI was observed in 6 of the 10 treated patients for whom all three biopsies were available, followed by a significant elevation on withdrawal of treatment. Changes in PCNA-MPI in the control group were less frequent and smaller.

CONCLUSIONS

Sandostatin causes a reduction in PCNA-MPI in patients with human colorectal cancer.

Inhibition of breast and ovarian carcinoma cell growth by 1,25-dihydroxyvitamin D3 combined with retinoic acid or dexamethasone

This study examined the growth inhibitory effects of combining 1,25-dihydroxyvitamin D3 (calcitriol) with retinoic acid or dexamethasone against cultured breast and ovarian carcinoma cells. Retinoic acid (12.5-50 nM) increased the effectiveness of calcitriol (12.5-50 nM) against MCF-7 and NIH:OVCAR3 cells, with synergistic interactions at two of the three ratios tested. Dexamethasone augmented calcitriol effects, with synergism at 0.05 and 0.1 nM dexamethasone in MCF-7 cells and 5 nM in Caov-4 ovarian cells. This study showed favorable interactions for calcitriol-retinoic acid and calcitriol-dexamethasone combinations in breast and ovarian cancer cell lines.

Possible mechanisms in the emergence of tamoxifen-resistant breast cancer

Tamoxifen (TAM), a non-steroidal antiestrogen, is the endocrine treatment of choice for all stages of breast cancer. However, despite a favorable initial response to therapy, most tumors will eventually exhibit TAM resistance resulting in disease recurrence. Several mechanisms of TAM resistance have been proposed, yet a single distinct mechanism has not been identified. We will systematically consider the following steps of the estrogen receptor (ER)-mediated signal transduction pathway to identify possible sites of alteration leading to tamoxifen-resistance: (1) ligand metabolism and availability, (2) loss or mutation of the ER, (3) defects in ER post-translational modification, and (4) alteration of the estrogen response element (ERE). In particular, the ERE will be discussed as a position in the signal transduction pathway with considerable potential, if altered, to confer TAM resistance.

Endometrial blood flow response to estrogen replacement therapy and tamoxifen in asymptomatic, postmenopausal women: a transvaginal Doppler study

This study was conducted to evaluate endometrial blood flow characteristics in response to estrogen replacement therapy (ERT) and tamoxifen in asymptomatic postmenopausal women, and to correlate the resistance index (RI) with plasma estradiol levels. Transvaginal color Doppler ultrasound examinations were performed in 30 asymptomatic, postmenopausal women who demonstrated thin endometria (< 0.5 cm). Ten healthy women receiving ERT and ten women with breast cancer receiving tamoxifen comprised the study groups. Ten postmenopausal women free of any hormonal treatment comprised the control group. Blood flow response was assessed by visualization of arterial waveforms in the endometrial region. Resistance indices were calculated for analysis and correlated with peripheral blood levels of estradiol. All postmenopausal women treated with tamoxifen or ERT showed continuous forward end-diastolic flow velocities, while the menopausal women without treatment demonstrated partial forward end-diastolic flow. Resistance index values of non-treated women were invariably higher (mean 0.89, range 0.85-0.91) than in those on tamoxifen (mean 0.79, range 0.54-0.90; p < 0.05), while the lowest RI was obtained in women taking ERT (mean 0.66, range 0.54-0.90; p < 0.05). The plasma concentrations of estradiol in women on ERT were found to be significantly higher than those of the tamoxifen and control groups. The observed data suggest that ERT and tamoxifen modify normal postmenopausal endometrial perfusion. Tamoxifen had a weaker estrogenic effect on the endometrial blood flow resistance, and ERT enhanced endometrial blood perfusion through vasodilatation.

Atypical androgen receptor in the human melanoma cell line IIB-MEL-J

To evaluate the presence of androgen receptors in the human melanoma cell line IIB-MEL-J, a Scatchard plot analysis was performed. Cells in culture revealed a single binding component with an apparent dissociation constant (KD) at 37 degrees C of 11 nM and a binding capacity of 326 fmol/mg protein when measured with [3H]-R1881. Competition analysis revealed an atypical relaxation of specificity, since not only androgen (testosterone, dihydrotestosterone [DHT], R1881) and antiandrogen (hydroxy-flutamide [OH-FLU]) competed for [3H]-R1881 binding, but also estradiol, progesterone, and cortisol at 500-fold excess concentration. Binding of [3H]-estradiol and [3H]-R5020 in the absence of unlabeled DHT were completely suppressed in its presence. Immunohistochemistry of androgen receptor with a monoclonal antibody showed that nuclei were vigorously stained. Different doses of flutamide (FLU) and OH-FLU tested on cultured IIB-MEL-J cells in the presence of serum inhibited significantly cell proliferation in a dose-dependent manner. When cells were incubated with 10 nM DHT and 1% charcoal-adsorbed serum, a significant stimulation of growth that was observed was inhibited by 4 microM OH-FLU. DHT stimulation was completely reversed by the antiestrogen tamoxifen. In addition, male nude mice transplanted with IIB-MEL-J tumor were treated with FLU when tumors were palpable. FLU was effective in diminishing tumor growth and increasing survival rate of the animals. As a conclusion, the presence of functional androgen receptors in these cells has been demonstrated by growth inhibition in vitro and in vivo with antiandrogens, and their atypical nature is suggested by binding cross-reactivity and competition studies.

Gynaecologic effects of tamoxifen

Tamoxifen, an estrogen antagonist, is widely used as adjuvant therapy in patients with breast cancer. Its efficacy in increasing survival and reducing recurrence rates has been demonstrated in several European and American studies. However, its effects appear to be tissue specific. Tamoxifen exerts an estrogen effect (agonist) on the endometrium, myometrium and vagina. An increase in uterine cancer has been confirmed in several placebo-controlled clinical trials. Due to the widespread use of this drug, it is timely to review the gynecologic effects of tamoxifen.

Androgen-controlled specific gene expression in neuroblastoma cells

In Kennedy's syndrome, a mutation in the androgen receptor (AR) gene leads to sensory and lower motor neurone degeneration, therefore genes that are regulated by androgens in neurones may be important in the process of motor neurone cell death. The aim of this study was to identify androgen-inducible genes in the human neuroblastoma cell line SH-SY5Y. We have shown that SH-SY5Y cells expressed the AR by Northern blot analysis using a 32P-labelled probe derived from a human AR cDNA. Differential display of mRNAs has been used to identify and clone putative genes that are regulated by androgens in SH-SY5Y cells. Nine cDNA fragments, ranging in size from 180 bp to 480 bp, corresponding to mRNA species which appear to be differentially expressed in response to 5 alpha dihydrotestosterone (DHT), have been successfully cloned. These are now being sequenced and used as hybridisation probes for Northern blot analysis in order to confirm their induction by DHT. Characterisation of these genes may provide clues to the mechanisms of motor neurone degeneration.

The effect of Toremifene on the expression of some genes in human mononuclear cells

Toremifene exerts multiple and varied effects on the gene expression of human peripheral mononuclear cells. After short-term, in vitro exposure to therapeutical levels, distinct changes in P-glycoprotein, steroid receptors, p53 and Bcl-2 expression take place. In view of the increasing use of antiestrogens in cancer therapy and prevention, there is obvious merit in long-term in vivo studies to be conducted.

The effects of dexamethasone on experimental brain tumors: I. Transcapillary transport and blood flow in RG-2 rat gliomas

Dexamethasone dramatically improves cerebral edema associated with malignant gliomas. Although the pathophysiology of this effect is not clearly understood, many investigators have postulated that tumor capillary permeability is reduced by dexamethasone. We studied blood-to-tissue transport and blood flow in 178 RG-2 transplanted gliomas in a control group and four groups given dexamethasone at doses of 3, 6, 9, and 12 mg/kg for four days. 14C-alpha aminoisobutyric acid (AIB) was used to study blood-to-tissue transport in 31 animals; in an additional 27 animals 14C-AIB and 131I-iodoantipyrine (IAP) were used in double label experiments to study blood-to-tissue transport and blood flow. Regional measurements of the transfer constant (K) of AIB and blood flow (F) were made with quantitative autoradiography. There were significant differences between the control and dexamethasone-treated groups with regard to weight loss and plasma glucose. However, there was no significant effect of dexamethasone on values of K or F, regardless of the tumor or brain region examined, and regardless of the dose of dexamethasone administered. Analysis of the profiles of the transfer constant of AIB in the brain around tumor showed that the K of AIB decreased within 0.5 mm of the tumor edge in direct relationship to the dexamethasone dose. These results do not support the hypothesis that dexamethasone reduces brain tumor capillary permeability, and suggest that dexamethasone may decrease tumor-associated cerebral edema by effects on bulk flow away from the tumor margin.