Regression of spontaneous mammary tumors in rats by ergot drugs

[Changes in the morphological structure of giant prolactinoma during treatment with cabergoline]

Currently, cabergoline therapy is the main method of treatment with prolactin. The use of the drug in most cases leads to tumor regression, normalization of prolactin levels and restoration of gonadotropic function. The mechanism of its impact on tumor cells in vivo, which is dynamically traced in the same human tumor, is the case of considerable interest. We observed a 30-year-old patient who was operated on twice for a giant prolactinoma before and on treatment by cabergoline. The morphological study after the first surgery (before introducing of cabergoline therapy) revealed a prolactin-positive pituitary tumor with a Ki-67 labeling index of 8% and with strong expression of dopamine type 2 receptors (D2R), CD31 and CD34. After 4 months, during which the patient received cabergoline at a dose starting from 0.5 mg to 1.5 mg per week, a second transsphenoidal surgery was performed with subtotal removal of residual tumor tissue. During the morphological study of the second biopsy sample, the tumor retained a pronounced immunopositivity to prolactin and D2R, with a decrease in the labeling index Ki-67 to 2%, as well as a decrease in the expression of CD31 and CD34. Subsequent cabergoline therapyresulted in persistent normoprolactinemia, restoration of androgen (and reproductive) status, and no tumor recurrence over a 10-year period on cabergoline treatment. Thus, one of the mechanisms of effect of cabergoline that leads to tumor regression is a decrease in the proliferative index and angiogenesis of the tumor.

Decrease of Proliferative Potential and Vascular Density of Giant Prolactinoma in Patients Treated with Cabergoline

Introduction:

Currently, cabergoline therapy is the main treatment for prolactinomas. The use of the drug in most cases leads to regression of the tumor, normalization of prolactin (PRL) levels, and restoration of gonadotropic function. The mechanism of its action in tumor cells “in vivo” tracked in dynamics in the same human tumor is of considerable interest.

Materials and Methods:

A 30-year-old male was admitted to N.N. Burdenko National Medical Research Center of Neurosurgery. An magnetic resonance imaging (MRI) revealed a giant pituitary adenoma. The level of PRL was more than 5000 mU/l (30-360) (serum dilution was not used to determine PRL). Transcranial microsurgical removal of the tumor was performed. He was treated by cabergoline after surgery. Endoscopic transsphenoidal approach was repeated with subtotal removal of the rest of the tumor. Morphological and immunohistochemical studies of the tumor were done.

Results:

A morphological study revealed PRL-positive tumor with a Ki-67 LI of 8% with a distinctive expression of D2R, CD31, and CD34 markers. Control MRI in 3 months after surgery revealed remnants of a tumor of endoinfrasellar localization, the tumor remainders were found in endoinfrasellar localization. The tumor retained pronounced immunopositivity to PRL and D2R and a decrease in the Ki-67 to 2% and in the expression of CD31 and CD34. Subsequent therapy with cabergoline resulted in persistent normoprolactinemia, restoration of androgenic function, and absence of tumor recurrence during the 10-year follow-up period.

Conclusions:

Cabergoline is an effective treatment for prolactinoma, which leads to tumor regression. One of its mechanisms is the reduction of the proliferative index and tumor angiogenesis.

Role of prolactin in chloro-S-triazine rat mammary tumorigenesis

Chloro-S-triazine herbicides [cyanazine (CZ), atrazine (AZ), simazine (SZ)] increase mammary tumors in Crl:CD BR rats but not in F-344 rats or in mice. A nongenotoxic mechanism was investigated since the chloro-S-triazines are negative in short-term tests for genotoxicity. An in vivo battery was used to assess the chloro-S-triazines for estrogenic activity or for their ability to increase prolactin (PRL) levels, both of which play important roles in enhancing mammary gland tumorigenesis in rodents. Ovariectomized (OVX) female rats were treated with AZ, CZ, SZ, or three CZ metabolites for 4 days via intraperitoneal injection. The pattern of responses between the chloro-S-triazines and four controls (estradiol, estriol, haloperidol, reserpine) was compared. For the 6 end-points examined, the responses from rats treated with AZ, CZ, SZ, and the metabolites of CZ most closely matched the responses from the reserpine-treated rats (a PRL rather than estrogenic mechanism). In addition, AZ, CZ, and SZ were tested in several other in vitro models (estrogen/biogenic amine receptor competition assays and a yeast-expressed human estrogen receptor transcription assay) as well as an in vivo 24 h time-course experiment to characterize the CZ-induced increases in PRL levels. AZ, CZ, and SZ are not estrogen receptor (ER) activating compounds based on yeast transactivation and receptor competition data. CZ and AZ demonstrated marginal competition (at mM levels) to the D and alpha2 adrenergic receptors. Ligands to the D2 receptor, but not the alpha2 adrenergic receptor, are known to induce mammary tumors. CZ was also found to produce elevated PRL levels in a time-course similar to that seen with reserpine and haloperidol. Overall, the pattern of responses obtained with the chloro-S-triazines most closely matched the responses observed for reserpine. Taken together, these data suggest chloro-S-triazine-induced mammary tumors in rats are mediated through a PRL mechanism, which is thought to be of low relevance to humans.

Antitumor effect of L-deprenyl in rats with carcinogen-induced mammary tumors

Deprenyl, a monoamine oxidase-B (MAO-B) inhibitor, has a wide range of pharmacological properties that are beneficial therapeutically in the treatment of human neurodegenerative diseases. Recent studies have demonstrated that deprenyl possesses a neuroprotective function that is not dependent on its MAO-B inhibitory activity. The focus of the present study was to investigate whether prolonged treatment of young Sprague-Dawley female rats with deprenyl before and after 9,10-dimethyl-1,2-benzanthracene (DMBA) administration would inhibit the development of mammary tumors by exerting a neuroprotective effect on the tuberoinfundibular dopaminergic (TIDA) neurons in the medial basal hypothalamus (MBH). For this purpose, the concentrations of catecholamines, indoleamine and their metabolites were measured in the MBH by high-performance liquid chromatography (HPLC) at the end of the treatment period. Female Sprague-Dawley rats (28-29 days old) were treated intraperitoneally with saline, or 0.25 or 2.5 mg of deprenyl/kg b.w. daily for 4 weeks prior to the administration of DMBA. Following the administration of DMBA, the rats were treated with saline or deprenyl daily for 27 weeks. At the end of the treatment period, there was a significant reduction in the tumor incidence and tumor number in rats that received 2.5 mg/kg deprenyl before and after the administration of DMBA and also in rats that were treated with 2.5 mg/ kg deprenyl following DMBA. There also was a significant decrease in tumor number in rats that were treated with 0.25 mg/kg deprenyl during the entire treatment period of 31 weeks. Body weight increased throughout the treatment period with no significant differences between the groups. Treatment of rats with 2.5 mg of deprenyl following the administration of DMBA and also during the entire treatment period resulted in a significant decrease in the concentrations of the metabolites of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) in the MBH, but there were no significant alterations in the concentrations of NE, DA and 5-HT in the MBH. These results suggest that the administration of deprenyl blocked the development of mammary tumors in part by inhibiting the metabolism of catecholamines and indoleamine and possibly by conferring a neuroprotective effect on the TIDA neurons in the MBH, especially at 0.25 mg/kg of deprenyl.

Two case reports of breast carcinoma associated with prolactinoma

Two cases of breast carcinoma associated with prolactinoma are presented. Literature review reveals only five previous case reports of this association. Both of our cases occurred in women, aged 55 and 34. Both were typical of the reported cases in that they had long histories of amenorrhea before diagnosis of prolactinomas and breast carcinomas. One patient had a three and a half year history of atypical ductal hyperplasia and a prominent intraduct component in the invasive tumor. Both had axillary lymph node metastases. The significance of the association of breast carcinoma with prolactinoma is discussed. Whereas studies in animals have shown prolactin to be an initiator and promoter of breast carcinoma, studies in humans have been inconclusive. Some studies have shown raised levels of prolactin in patients with breast carcinoma and their daughters, while others have not. The paucity of case reports linking breast carcinoma and prolactinoma may indicate that the association is mere coincidence, but studies evaluating the relationship between breast carcinoma and all forms of hyperprolactinemia need to be conducted before a causal link is dismissed. Prolactin may act as a cofactor with, for example, estrogen or stress, to induce breast carcinoma.

Breast cancer in a male patient with prolactinoma

A 68-year-old man was diagnosed as having left primary breast cancer. Systemic bone roentgenography showed no evident metastasis, however, skull roentgenography revealed ballooning of the sella turcica, suggesting a pituitary tumor, which was subsequently confirmed by computed tomography. Because there was a high serum prolactin level, the pituitary tumor was diagnosed as a prolactinoma. A modified radical mastectomy was performed for the breast cancer, and bromocriptine therapy given for the prolactinoma. Prolactin is known to initiate and promote breast cancer in mice and rats but little is known about its role in human breast cancer. If hyperprolactinemia plays an important role in the tumorigenesis of human breast cancer as it does in mice and rats, the incidence of breast cancer in patients with hyperprolactinemia may be high. To our knowledge, however, only four such cases have been reported. The present rare case of male breast cancer with prolactinoma is discussed with reference to the literature.

Effect of bromocriptine on the ovarian cycle of two inbred strains of mice

Mice of the C3H/Sy (high incidence of spontaneous mammary cancer) and AKR/Sy (low incidence of spontaneous mammary cancer) inbred strains, which have different hormonal profiles, were injected daily with bromocriptine for 1 month. The treatment increased the duration of the ovarian cycle of the AKR/Sy mice, whereas that of the C3H/Sy mice was not affected. It is suggested that the effect of bromocriptine on the ovarian cycle depends on the concentrations of plasma progesterone reached in each strain of mouse.

Characteristics of 106 spontaneous mammary tumours appearing in Sprague-Dawley female rats

Pathological studies were undertaken on 106 mammary tumours (89 benign, 17 malignant) appearing spontaneously in 95 normal female Sprague-Dawley rats which were killed at Day 756. The benign tumours comprised those with a predominant acinar hyperplasia and those with adenomatous or fibroadenomatous pattern. No significant differences were found histochemically between the acinar cells of the benign tumours and of the lactating gland, except that the amount of fibrous interstitial connective tissue was larger in the former. 3H- or 35S-glycosaminoglycan synthesis by the benign tumours was found to be much higher. The prolactin value in the plasma of the benign-tumour-bearing rats was about 27 times that of 6-month-old virgin rats, and similar to that of rats on the 7th day post partum. Carcinomatous proliferation of tubuloacinar cells could be seen in 5 of the 89 benign tumours. The incidence of benign tumours increases with the age of the rats.

Suppression of puerperal lactation with an ergot alkaloid: a double-blind study

A double-blind trial was performed in 60 women to establish the effectiveness of an ergot alkaloid, 2-Br-alpha-ergocryptine (ergocryptine; CB 154), in suppressing puerperal lactation and to compare it with stilboestrol and a placebo. At the doses selected ergocryptine and stilboestrol were equally effective.

Ergot-induced inhibition of pituitary tumor growth in rats

Daily injections of ergocornine or ergonovine, for 3 weeks, into rats carrying a prolactin- and growth hormone-secreting pituitary tumor (MtW15) induced significant regression or inhibition of tumor growth, whereas ergocryptine had no significant effect. Ergocornine caused a decrease in cells and a disappearance or pycnosis of nuclei in the tumor tissue, and a reduced concentration of prolactin in blood.