N-methyl-N-nitrosourea-induced mammary carcinogenesis is promoted by short-term treatment with estrogen and progesterone mimicking pregnancy in aged female Lewis rats.

We examined the effects of short-term estrogen and progesterone treatment mimicking pregnancy in aged female Lewis rats on the development of N-methyl-N-nitrosourea (MNU)-induced mammary carcinoma. Rats were administered a single intraperitoneal injection of 20 mg/kg MNU at 7 weeks of age and half of those rats were administered a subcutaneously implanted 21-day release pellet containing 0.5 mg 17beta-estradiol and 32.5 mg progesterone (E/P) at 24 weeks of age. The rats were then monitored for the occurrence of mammary tumors. Rats were sacrificed when the largest mammary tumor became > or = 1 cm in diameter, or when the rat reached 48 weeks of age. Development of MNU-induced mammary carcinomas was accelerated after short-term E/P treatment, compared with E/P-untreated rats: the incidence of > or = 1-cm mammary carcinomas tended to increase (60 vs. 44%); the latency tended to shorten (28.7 vs. 34.6 weeks); and cancer multiplicity (number of all-sized carcinomas per rat) significantly increased (1.8 vs. 0.8). In E/P-treated rats, comedo necrosis was frequently seen and the incidence of estrogen receptor and/or progesterone receptor-negative mammary carcinomas was significantly increased. Early age at full-term pregnancy or short-term hormone treatment mimicking pregnancy may suppress the risk of breast cancer, but the age of hormone exposure is a crucial factor, because hormone exposure mimicking pregnancy in aged individuals may exert effects opposite of those exerted in younger individuals.

Autopsy case of desminopathy involving skeletal and cardiac muscle.

Desminopathy is a familial or sporadic skeletal and cardiac muscular dystrophy caused by mutation in the desmin gene. Desmin-reactive deposits in the affected muscles are the morphological hallmarks of this disease. Herein is reported an autopsy case of a 57-year-old Japanese man with adult-onset skeletal muscle weakness and atrioventricular (A-V) conducting block, with a missense A337P mutation in exon 5 of the desmin gene. Disease onset occurred when the patient was 45 years old. The initial presentation was lower limb weakness, and the weakness progressed to the upper limbs. When the patient was 51 years old, a cardiac pacemaker was implanted due to complete A-V block. When the patient was 53 years old, respiratory insufficiency occurred due to weakness of respiratory muscles, and the patient died at the age of 57 years. On autopsy, intrasarcoplasmic desmin-immunoreactive deposits were identified in the skeletal and cardiac muscle, and abnormal accumulations of granulofilamentous material were identified at the ultrastructural level. In the cardiac conducting system, calcification was observed at the bundle of His, and sporadic calcium deposits were observed at the left and right bundle branches.

Biphasic effects of zeranol on the growth of estrogen receptor-positive human breast carcinoma cells.

Zeranol (alpha-zearalanol) is a metabolite of the mycoestrogen zearalenone, and is used as a growth promoter of livestock due to its strong estrogenic activity. In the present study, we investigated the effects of zeranol on the growth of estrogen receptor (ER)-positive and -negative human breast carcinoma cells in vitro, and the molecules involved. At low concentrations, zeranol accelerated the growth of ER-positive MCF-7 and KPL-1 human breast carcinoma cells, but did not affect the growth of ER-negative MDA-MB-231 cells. At high concentrations, zeranol suppressed the growth of both ER-positive and -negative human breast carcinoma cells. The acceleration of ER-positive cell growth by low-dose zeranol involved the down-regulation of p21Cip1 (a cyclin-dependent kinase inhibitor), which resulted in cell cycle progression. High-dose zeranol induced the formation of a sub-G1 fraction and the up-regulation of the apoptosis stimulator p53, suggesting the induction of apoptosis. Thus, zeranol exerted dose-dependent biphasic effects on ER-positive human breast carcinoma cells, accelerating cell growth at low concentrations and inducing apoptosis at high concentrations.

An autopsy case of primary mixed choriocarcinoma and mature teratoma located in the thymic region associated with elevated human chorionic gonadotropin levels and characteristic testicular changes.

An autopsy case of a 19-year-old male Japanese student with a primary mixed choriocarcinoma and mature teratoma in the thymic region is reported. The patient died 7 days after he first noticed fever and dyspnea. On autopsy, an anterior mediastinal mass was found to be in contact with the thymic gland. The mass weighed 270 g and measured 12.5 cm x 10 cm x 5 cm. The left thoracic cavity contained 2200 ml bloody pleural effusion and 200 g coagula due to hemorrhage from the tumor. Metastasized choriocarcinoma was seen in both lungs and the liver. High serum levels of human chorionic gonadotropin (HCG, 1 634 000 mIU/ml) and a decreased weight of the testes (2.0 g each) with Leydig cell hyperplasia/hypertrophy and the seminiferous tubules with hyaline ghost tubules or Sertoli cell only tubules were seen; other male reproductive organs were histologically normal. Although the serum testosterone level was within the normal range (5.75 ng/ml), luteinizing hormone (LH, 0.1 mIU/ml) and follicle-stimulating hormone (FSH, 0.3 mIU/ml) levels were decreased. High serum levels of HCG and characteristic testicular changes are drscribed.

Nicotinamide blocks N-methyl-N-nitrosourea-induced photoreceptor cell apoptosis in rats through poly (ADP-ribose) polymerase activity and Jun N-terminal kinase/activator protein-1 pathway inhibition.

Nicotinamide (NAM) blocks N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell apoptosis in rats, though the underlying molecular mechanisms remain unclear. Activation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP) in response to DNA damage plays a pivotal role in apoptosis. Thus, the role of NAM in the regulation of PARP and Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) was investigated by Western blot analyses. During 7 days after the intraperitoneal injection of MNU (60 mg/kg), rat retinas exhibited DNA fragmentation characteristic of apoptosis and activation of PARP, phosphorylation of JNK and c-Jun, induction of AP-1 (c-Jun and c-Fos) and Bax, as well as photoreceptor cell loss. However, when NAM (1000 mg/kg, subcutaneously) was given immediately after MNU, it was found that PARP activation was diminished, the phosphorylation of JNK and c-Jun was suppressed, and the induction of c-Jun, c-Fos and Bax was suppressed. This resulted in the retinal structure being protected. Therefore, NAM blocked MNU-induced photoreceptor cell apoptosis by inhibiting both PARP activity and the JNK/AP-1 signalling pathway.

Effects of different durations of estrogen and progesterone treatment on development of N-methyl-N-nitrosourea-induced mammary carcinomas in female Lewis rats.

BACKGROUND: There have been no precise evaluations of the effects of different durations of exposure to estrogen and progesterone pregnancy levels on mammary carcinogenesis risk. We examined such effects on the development of N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinoma. MATERIALS AND METHODS: Female Lewis rats were administered a single intraperitoneal injection of 50 mg/kg MNU at 28 days of age, and then were either left hormone-untreated (control group), or underwent subcutaneous implantation of a 21-day release pellet containing 0.5 mg 17beta-estradiol and 32.5 mg progesterone (E/P pellet) at 42 days of age. The pellet was either replaced every 3 to 4 weeks throughout the experimental period (long-term E/P group), or was implanted only once (short-term E/P group). Circulating 17beta-estradiol and progesterone levels in the serum, and expression of estrogen receptor (ER) a and progesterone receptor (PgR) in the normal mammary gland were measured. The rats were sacrificed when they developed a mammary tumor with a diameter of > or =1 cm, or when they reached the age of 29 weeks. RESULTS: In rats implanted with a single E/P pellet, circulating 17beta-estradiol and progesterone levels were significantly elevated 2 weeks after implantation, but returned to control levels 8 weeks after implantation; 17beta-estradiol transiently reached pregnancy levels. In normal mammary glands of rats sacrificed at 29 weeks of age, both long- and short-term E/P treatment decreased the percentage of ERalpha- and PgR-positive cells. Rats that received long- or short-term E/P treatment had a decreased incidence of mammary carcinoma with a diameter of > or =1 cm, compared to control rats. However, when histologically detected microcarcinomas (diameter <1 cm) were included for comparison, the E/P-treated groups exhibited an abrupt increase in the number of microcarcinomas from 22 to 25 weeks after MNU injection. Although short-term E/P treatment significantly suppressed mammary carcinomas of all sizes, long-term E/P treatment had no cancer-suppressing effect. CONCLUSION: The duration of E/P treatment is an essential factor for the suppression of mammary carcinogenesis.

Enterolactone induces apoptosis and inhibits growth of Colo 201 human colon cancer cells both in vitro and in vivo.

BACKGROUND: The mammalian lignan enterolactone (ENL) is produced from plant lignans which are present in large amounts in flaxseed (linseed). The effect of ENL on colon cancer cell growth in vitro and in vivo, and its mechanisms of action, have not been studied in detail. MATERIALS AND METHODS: The growth of the colo 201 human colon cancer cell line was examined by colorimetric 3-(4,5-dimethylthiazol-2-yl)-5- (3-carboxymethoxyphenyl)-2- (4-sulphophenyl)-2H-tetrazolium (MTS) assay, while the expression of apoptosis- and proliferation-related proteins (p53, Bax, Bcl-xL and S, Bcl-2, Caspase-8, Caspase-3 and proliferating cell nuclear antigen (PCNA)) were examined by Western blotting. In vivo tumor growth was examined by transplanting colo 201 cells into ENL-treated and placebo-treated athymic mice. RESULTS: The MTS assay showed that ENL suppressed colo 201 cell growth (IC50 for 72 h: 118.4 microM) in vitro. On flow cytometry, induction of apoptosis was confirmed by the appearance of subG1 populations, while cell cycle progression was not affected. The expression of an apoptosis-suppressing protein (Bcl-2) was down-regulated, an apoptosis-enhancing protein (cleaved form of Caspase-3) was up-regulated, proliferation-related PCNA protein was down-regulated and p53, Bax, Bcl-xL and S and Caspase-8 levels were unchanged. ENL, at a dose of 10 mg/kg given 3 times per week by subcutaneous injection, significantly inhibited the growth of colo 201 cells transplanted into athymic mice without any adverse effects. CONCLUSION: ENL suppressed colo 201 human colon cancer cell growth both in vitro and in vivo. The tumor-suppressing mechanisms included apoptosis and decreased cell proliferation.

Influence of cure of Helicobacter pylori infection on gastric acidity and gastroesophageal reflux: study by 24-h pH monitoring in patients with gastric or duodenal ulcer.

BACKGROUND: Whether or not the eradication of Helicobacter pylori is a risk factor for reflux esophagitis (RE) is a question at issue. To find an answer, it is necessary to clarify the influence of H. pylori eradication on the mechanism of RE. METHODS: The authors investigated the influence of H. pylori eradication on gastric acidity and gastroesophageal reflux in ten gastric ulcer (GU) patients and ten duodenal ulcer (DU) patients by 24-h simultaneous determination of pH in the stomach and esophagus. RESULTS: Though the results indicated enhanced gastric acidity in GU patients at night after H. pylori eradication, no such influence was observed in DU patients. No significant changes in gastroesophageal reflux occurred in GU or DU patients before and after H. pylori eradication. RE after H. pylori eradication occurred in only one patient, with GU. This patient had several risk factors for RE, such as obesity, male sex, and dietary habits to add to the increase in gastric acidity at night that occurred after H. pylori eradication. No increase in gastroesophageal reflux occurred in any DU patients or in the other GU patients that demonstrated enhanced gastric acidity at night after H. pylori eradication. CONCLUSIONS: The cure of H. pylori infection does not, by itself, cause RE in patients who have few other risk factors for RE.