A role of interferon-gamma (IFN-gamma) in tumor immunity: T cells with the capacity to reject tumor cells are generated but fail to migrate to tumor sites in IFN-gamma-deficient mice

IFN-gamma-deficient (IFN-gamma-/-) mice induce potent in vitro immune responses such as anti-allo mixed lymphocyte reaction and CTL responses, whereas they often fail to exhibit in vivo immunity. Here, we investigated whether there exists a defect in tumor rejection responses and if so, which process of responses is impaired. IFN-gamma-/- and wild-type (WT) BALB/c mice were immunized with attenuated syngeneic CSA1M tumor cells. The capacity of T cells to mediate tumor protection was examined in Winn assays to assess the growth of tumor cells admixed with tumor-sensitized T cells. Splenic T cells from both groups of mice exhibited comparable levels of tumor-neutralizing activity. When portions of immunized mice were directly challenged with viable tumor cells, tumor rejection was induced only in WT mice. CD4(+) and CD8(+) T-cell infiltration were observed at the site of tumor challenge in WT mice, whereas such a T-cell infiltration did not occur in IFN-gamma-/- mice. Similarly, splenic T cells from interleukin 12-treated CSA1M-bearing IFN-gamma-/- and WT mice neutralized tumor cells at comparable efficacies in Winn assays. However, the migration of these T cells to tumor masses and the resultant interleukin 12-induced tumor regression took place in WT mice, but neither intratumoral T-cell infiltration nor tumor regression occurred in IFN-gamma-/- mice. These results indicate a critical requirement for IFN-gamma in the process of inducing T-cell migration to tumor sites rather than of generating antitumor protective T cells.

Anorexia nervosa with ischemic necrosis of the segmental ileum and cecum

A 41-year-old woman with long-standing anorexia nervosa showed paralytic ileus and serum creatine kinase elevation. Surgical treatment showed necrosis of the segmental ileum and cecum with perforation. She died of septic shock 3 days after the operation. Postmortem examination revealed no occlusion of the superior mesenteric artery or its main branches, and no arteriosclerotic changes. Histological examinations confirmed non-occlusive mesenteric infarction. This case suggested that necrosis of bowels might have been caused by poor blood supply due to severe malnutrition and dehydration for many years, which could be one of the fatal complications of anorexia nervosa.

Expression of osteopontin by exudate macrophages in inflammatory tissues of the middle ear: a possible association with development of tympanosclerosis

Tympanosclerosis is a condition leading to a calcification process in the middle ear, and often develops after chronic inflammation of the middle ear. Since osteopontin (OPN) has been shown to participate in the pathological calcification, we here investigated whether OPN is involved in the process of calcification in tympanosclerosis. The tympanic membrane and middle ear mucosa, obtained from patients of tympanosclerosis and chronic otitis media, were histologically classified depending on the calcification degree. In hyalinized tissues with macroscopic calcification and fibrous tissues with microscopic calcification, OPN was immunohistochemically found in the calcification sites. In inflammatory tissues with microscopic calcification, OPN was also found in the calcifying foci, and many OPN mRNA-expressing cells, determined by in situ hybridization, located around their foci. Moreover, immunohistochemical double staining of OPN and CD68 showed that the OPN-expressing cells were CD68-positive, indicating these cells were macrophages. In inflammatory tissues without calcification, immunohistochemistry of CD68 and in situ hybridization of OPN mRNA revealed that most OPN mRNA-expressing cells were CD68-positive. The expression of OPN mRNA in inflammatory tissues was also shown by reverse transcriptase polymerase chain reaction. These results suggest that OPN secreted by exudate macrophages might be an important regulator in the calcification of tympanosclerosis.

Interleukin-18 up-regulates osteoprotegerin expression in stromal/osteoblastic cells

Osteoprotegerin (OPG) and osteoclast differentiation factor (ODF) are crucial regulators of osteoclastogenesis. To determine the biological role of interleukin (IL)-18 produced by stromal/osteoblastic cells in osteoclastogenesis, we examined the effects of IL-18 on the OPG and ODF mRNA levels in these cells. When bone marrow stromal ST2 cells, osteoblastic MC3T3-E1 cells, and mouse calvarial osteoblasts were stimulated with IL-18, the expression of OPG mRNA, but not ODF mRNA, was transiently increased, its expression reaching a maximal level at 3 h after the beginning of the culture. In accordance with this observation, all these cells expressed the mRNAs of two IL-18 receptor components and MyD88, an adapter molecule involved in IL-18 signaling. Moreover, in these cells, mitogen-activated protein kinase was phosphorylated after stimulation with IL-18. These results suggest that stromal/osteoblastic cells are IL-18-responsive cells and that IL-18 may inhibit osteoclastogenesis by up-regulating OPG expression, without stimulation of ODF production, in stromal/osteoblastic cells.

Syk protein-tyrosine kinase is involved in neuron-like differentiation of embryonal carcinoma P19 cells

Syk has been implicated in activated immunoreceptors to downstream signaling events in hematopoietic cells. Here we report that Syk is expressed in neuron-like cells and involved in neuron-like differentiation of embryonal carcinoma P19 cells. Immunoblot, RT-PCR, and Northern analysis indicated that Syk is expressed in mouse brain, PC12 and P19 cells. In addition, Syk was found to be tyrosine phosphorylated during neuron-like differentiation of P19 cells. Furthermore, adenovirus-mediated overexpression of Syk induced supernumerary neurite formation and extracellular signal-regulated kinase (ERK) activation in P19 cells. These results suggest that Syk plays an important role in signaling steps leading to ERK activation in P19 cells.

Guinea pig histamine N-methyltransferase: cDNA cloning and mRNA distribution

We report here the isolation of histamine N-methyltransferase (HMT) cDNA from the guinea pig brain by the polymerase chain reaction on the basis of nucleotide sequences of rat and human counterparts. Guinea pig HMT consists of 292 amino acids, with homologies of 75.6% and 79.1% to rat and human HMT, respectively. Northern blotting analysis indicated that the 1.6-kb guinea pig HMT transcript was expressed at various levels in different tissues at the following relative abundance: jejunum, brain > lung, spleen, stomach > liver, kidney. HMT mRNA localized throughout the jejunum, and it was mainly expressed in epithelial cells and in Auerbach's plexus.

Tumor vaccination that enhances antitumor T-cell responses does not inhibit the growth of established tumors even in combination with interleukin-12 treatment: the importance of inducing intratumoral T-cell migration

Interleukin-12 (IL-12) treatment is effective in the CSA1M but not in the Meth A and CSA1M-variant tumor models. The authors investigated the cause by which IL-12 treatment fails to induce tumor regression in these two tumor models. T cells from CSA1M-bearing mice have high levels of IL-12 responsiveness, whereas cells from Meth A-bearing mice display marginal levels of responsiveness. Because IL-12 responsiveness in T cells is induced after T-cell receptor stimulation, the lack of IL-12 responsiveness suggests that T cells in Meth A-bearing mice are not sensitized to Meth A tumor antigen. Immunization of normal mice with attenuated Meth A tumor cells resulted in a protective immunity, as shown by the rejection of challenged viable Meth A cells. Such an immunization, when performed in Meth A-bearing mice, induced potent IL-12 responsiveness in T cells. Nevertheless, IL-12 treatment in these mice did not inhibit tumor growth. In another IL-12-incurable (CSA1M-variant) model, IL-12 responsiveness was observed before tumor cell immunization. However, IL-12 treatment was ineffective regardless of whether tumor cell immunization was performed. In these two models, the failure of IL-12 treatment to induce tumor regression was associated with the lack of T-cell migration to tumor sites. These results indicate that the sensitization of T cells to tumor antigens and generation of IL-12 responsiveness are insufficient to induce tumor regression when these sensitized T cells are not allowed to migrate to tumor sites.

Identification of CRAM, a novel unc-33 gene family protein that associates with CRMP3 and protein-tyrosine kinase(s) in the developing rat brain

Four members of collapsin response mediator proteins (CRMPs) are thought to be involved in the semaphorin-induced growth cone collapse during neural development. Here we report the identification of a novel CRMP3-associated protein, designated CRAM for CRMP3-associated molecule, that belongs to the unc-33 gene family. The deduced amino acid sequence reveals that the CRAM gene encodes a protein of 563 amino acids, shows 57% identity with dihydropyrimidinase, and shows 50-51% identity with CRMPs. CRAM appears to form a large complex composed of CRMP3 and other unidentified proteins in vivo. Indeed, CRAM physically associates with CRMP3 when co-expressed in COS-7 cells. The expression of CRAM is brain-specific, is high in fetal and neonatal rat brain, and decreases to very low levels in adult brain. Moreover, CRAM expression is up-regulated during neuronal differentiation of embryonal carcinoma P19 and PC12 cells. Finally, immunoprecipitation analysis of rat brain extracts shows that CRAM is co-immunoprecipitated with proteins that contain protein-tyrosine kinase activity. Taken together, our results suggest that CRAM, which interacts with CRMP3 and protein-tyrosine kinase(s), is a new member of an emerging family of molecules that potentially mediate signals involved in the guidance and outgrowth of axons.

Molecular analysis of zebrafish photolyase/cryptochrome family: two types of cryptochromes present in zebrafish

BACKGROUND

Cryptochromes (CRY), members of the DNA photolyase/cryptochrome protein family, regulate the circadian clock in animals and plants. Two types of animal CRYs are known, mammalian CRY and Drosophila CRY. Both CRYs participate in the regulation of circadian rhythm, but they have different light dependencies for their reactions and have different effects on the negative feedback loop which generates a circadian oscillation of gene expression. Mammalian CRYs act as a potent inhibitor of transcriptional activator whose reactions do not depend on light, but Drosophila CRY functions as a light-dependent suppressor of transcriptional inhibitor.

RESULTS

We cloned seven zebrafish genes that carry members of the DNA photolyase/cryptochrome protein family; one (6-4)photolyase and six cry genes. A sequence analysis and determination of their in vitro functions showed that these zebrafish cry genes constitute two groups. One has a high sequence similarity to mammalian cry genes and inhibits CLOCK:BMAL1 mediated transcription. The other, which has a higher sequence similarity to the Drosophila cry gene rather than the mammalian cry genes, does not carry transcription inhibitor activity. The expressions of these cry genes oscillate in a circadian manner, but their patterns differ.

CONCLUSIONS

These findings suggest that functionally diverse cry genes are present in zebrafish and each gene has different role in the molecular clock.

The role of oval cells in rat hepatocyte transplantation

BACKGROUND

Oval cells are liver cells capable of differentiating into either hepatocytes or biliary epithelial cells. We compared growth of hepatocytes and biliary epithelial cells between spleens transplanted with oval cell-free and oval cell-enriched rat liver cells.

METHODS

Oval cell-enriched liver cells were obtained from livers of adult rats that had undergone treatment with acetylaminofluorene and partial hepatectomy, although oval cell-free liver cells were obtained from livers of untreated rats. Hepatocyte and biliary epithelial cell growth in the spleen was evaluated by counting periodic acid-Schiff-positive cells and cytokeratin 19-positive cells respectively in sections from transplanted spleens.

RESULTS

Spleens transplanted with oval cell-free liver cells and spleens transplanted with oval cell-enriched liver cells contained similar numbers of hepatocytes after 2 weeks. Numbers of hepatocytes in spleens transplanted with oval cell-free liver cells decreased markedly at 4 and 8 weeks, then increasing slightly until 32 weeks. In spleens transplanted with oval cell-enriched liver cells, numbers of hepatocytes decreased only slightly at 4 weeks and then increased markedly. At 4, 8, 12, 16, 24, and 32 weeks, numbers of hepatocytes in spleens transplanted with oval cell-enriched liver cells respectively were 2.3, 3.5, 4.5, 6.7, 6.3, and 15.1 times hepatocyte numbers in spleens transplanted with oval cell-free liver cells. Numbers of biliary epithelial cells in spleens receiving oval cell-enriched liver cells showed changes similar to those in spleens transplanted with oval cell-free liver cells, increasing markedly at 4 weeks and then markedly and rapidly decreasing.

CONCLUSIONS

Intrasplenic transplantation of oval cell-enriched liver cells enhanced growth of hepatocytes compared with transplantation of oval cell-free liver cells; this was not true for biliary epithelial cells.

Inhibition by an angiogenesis inhibitor, TNP-470, of the growth of a human hepatoblastoma heterotransplanted into nude mice

BACKGROUND/PURPOSE

The effect of TNP-470, an angiogenesis inhibitor, on the growth of a hepatoblastoma transplanted into nude mice was examined.

METHODS

A hepatoblastoma obtained from a 3-year-old girl was serially transplanted into nude mice subcutaneously, and the transplant tumors of the seventh and eighth generations were used for experiments. Expression of various markers in the tumors was examined immunohistochemically. TNP-470 was injected subcutaneously every other day into tumor-bearing mice from 3 weeks after tumor transplantation. The proliferation of tumor cells and endothelial cells was estimated by means of the bromodeoxyuridine labeling index.

RESULTS

The original hepatoblastoma showed the histology of the epithelial type, consisting of both the fetal and embryonal subtypes and was positively stained with anti-alpha-fetoprotein (AFP), anti-cytokeratin-19 and polyclonal anticarcinoembryonic antigen antibodies, and an antihuman hepatocyte antibody (hepatocyte paraffin 1). The transplant tumors consisted of solid nests of tumor cells with numerous vascular lakes of various sizes, and showed positive staining with all antibodies that reacted positively with the original hepatoblastoma. Injections of TNP-470 at the doses of 15 mg and 30 mg/kg body weight suppressed the tumor growth and the increase in the serum level of AFP dose dependently. Injections of TNP-470 also suppressed the proliferation of tumor cells and endothelial cells in the tumors.

CONCLUSIONS

Hepatoblastomas maintained in nude mice retained the immunohistochemical characteristics of the original hepatoblastoma, and TNP-470 suppressed the growth of hepatoblastomas transplanted into nude mice. TNP-470 may be worth investigating further as to its usefulness as a therapy for hepatoblastomas.

The development of peritumoral stroma required for IL-12 induced tumor regression depends on the T cell/IFN-gamma-involving host-tumor interaction

T cell migration into tumor masses is a critical process in the scenario of IL-12-induced tumor regression. Our previous study showed that this depends on the development of peritumoral stroma prior to IL-12 therapy. The present study investigated the regulation of the development of peritumoral stroma in comparison with tumor-parenchymal stroma. In the OV-HM and CSA1M tumor models, tumor regression associated with T cell migration was induced following IL-12 treatment. Both OV-HM and CSA1M tumor masses growing in syngeneic mice developed peritumoral stroma before IL-12 treatment. However, peritumoral stroma was not observed in these two types of tumor masses generated in nude mice, T cell-depleted syngeneic mice, anti-IFN-gamma mAb-treated mice or IFN-gamma-deficient mice. In contrast, parenchymal stroma formation did not appear to be affected because tumors generated in these groups of mice exhibited rather higher growth rates than those of tumors in normal syngeneic mice. Importantly, the lack of peritumoral stroma in tumor masses was associated with the failure of T cells to migrate to these tumor masses: splenic T cells prepared from IL-12-treated tumor-bearing mice migrated into the corresponding tumor mass growing in untreated syngeneic recipient mice, whereas portions of the same donor cells failed to migrate into the above stroma-negative tumor masses. These results indicate that the development of peritumoral and parenchymal stroma is differentially regulated; there exist functional differences in the two types of stroma; and the formation of peritumoral stroma requires components of the host's immune system such as IFN-gamma and T cells.

Purification of a 72-kDa protein-tyrosine kinase from rat liver and its identification as Syk: involvement of Syk in signaling events of hepatocytes

Syk protein-tyrosine kinase (PTK) has been implicated in a variety of hematopoietic cell responses including immunoreceptor signaling. However, so far, there has been no evidence of the expression of Syk or Syk-related PTK in non-hematopoietic tissues. In this study, we have purified from blood cell-depleted rat liver a 72-kDa cytoplasmic PTK which shows cross-reactivity with anti-Syk antibody. Partial amino acid sequence analysis revealed that this 72-kDa PTK is identical to Syk. Immunohistochemical and RT-PCR analyses demonstrated that Syk is expressed in human hepatocytes and two rat liver-derived cell lines, JTC-27 and RLC-16. Furthermore, Syk is significantly tyrosine-phosphorylated in response to angiotensin II in JTC-27 cells, and angiotensin II-induced MAP kinase activation is blocked by the treatment of cells with a Syk-selective inhibitor, piceatannol. These results suggest that Syk plays an important role in signaling events of hepatocytes, such as signaling steps leading to MAP kinase activation by G-protein-coupled receptors. This is the first report of the expression of Syk in non-hematopoietic tissue.

Comparison of sensitivities of uterine cells in their proliferation responding to epidermal growth factor and estrogen between neonatal and postneonatal mice

The uteri of mice up to 20 days after birth show estrogen-independent growth, although their growth is accelerated by estrogen, while the growth of the uteri of mice after 20 days completely depends on estrogen. In the present study, we compared the sensitivities of uterine cells in their proliferation responding to epidermal growth factor (EGF) and diethylstilbestrol (DES) between 5-day-old and 25-day-old ovariectomized mice. A single subcutaneous injection of EGF at doses of 0.25 and over 0.25 microgram/g body weight (BW) increased 3H-thymidine uptake by the whole uterus dose-dependently in both 25-day-old and 5-day-old mice, and a maximal increase in the 3H-thymidine uptake was attained at a dose of 1 microgram/g BW of EGF in both mice. A single subcutaneous injection of DES at 0.001 and over 0.001 microgram/g BW increased 3H-thymidine uptake by the whole uterus dose-dependently in both 25-day-old and 5-day-old mice, and a maximal increase was attained at 0.004 microgram/g BW of DES in both mice. EGF and DES increased labeling indices of both the epithelium and stroma in both 25-day-old and 5-day-old mice. The present results suggest that sensitivities of uterine cells of neonatal mice in their proliferation responding to EGF and DES are similar to those of postneonatal mice.

Inhibition by interleukin 18 of osteolytic bone metastasis by human breast cancer cells

Effects of interleukin (IL)-18 on experimental bone metastasis of human breast cancer cells, MDA-231 cells, in nude mice were investigated. In addition, effects of IL-18 on subcutaneous growth of MDA-231 cells were examined. Bone metastasis was produced by an intracardiac injection of MDA-231 cells. Twenty eight days after the cell injection, severe osteolytic bone metastasis was examined by X-ray radiography, and both non-osteolytic and osteolytic bone metastases were examined microscopically. IL-18 (1 microgram/mouse) was injected intraperitoneally according to protocols A and B. In protocol A, IL-18 was injected daily from day 7 after an intracardiac or subcutaneous injection of cells, and in protocol B, it was injected daily for 7 days each before and after the cell injection. In protocol A, IL-18 injections significantly suppressed both the incidence of osteolytic bone metastasis detected by X-ray radiography (about 80% vs. about 20% for the control group vs. the treatment group) and the number of its foci/mouse (1.6 vs. 1 for the control group vs. the treatment group). However, they did not cause significant effects on either the incidence of bone metastasis detected microscopically or the number of its foci/mouse. In protocol B, IL-18 injections caused no significant effects on either the incidence of osteolytic bone metastasis detected by X-ray radiography or the number of its foci/mouse. They caused no significant effects on the incidence of bone metastasis detected microscopically, but significantly decreased the number of its foci/mouse (about 2.0 vs. about 1 for the control group vs. the treatment group). In both protocols A and B, IL-18 injections produced no significant effect on the tumor take and subsequent growth of tumors after a subcutaneous injection of the cancer cells. Since in protocol A, IL-18 appears to have exerted its action after establishment of metastasis by cancer cells to the bone marrow, the effects of IL-18 found in Protocol A indicate that IL-18 inhibited osteolytic growth at bone metastatic sites of breast cancers. On the other hand, since in protocol B IL-18 is likely to have functioned around the time when lodging of cancer cells and early development of metastasis occur in the bone marrow, the effects of IL-18 found in Protocol B indicate that the cytokine also suppresses an early stage of bone metastasis of breast cancers, although, this effect was less apparent than the effect on osteolytic growth. Therefore, IL-18 may be useful for suppression of osteolytic bone metastasis which is a serious problem in patients of advanced breast cancers.

[A patient with meningeal carcinomatosis accompanied by a small pituitary metastatic lesion from gastric cancer who developed cerebral salt wasting syndrome]

A 68-year-old man with disturbed consciousness had repeatedly developed light-headedness and dizziness since the summer of 1996 and was admitted to a hospital for detailed examinations on October 8, 1996. On admission, he weighed 49 kg and showed subclinical hypothyroidism with low T3 syndrome. The adrenal function and serum electrolytes were normal. Since the stool samples were positive for occult blood, gastroscopy was performed. Examination of the biopsy specimens demonstrated gastric cancer. On October 21, blood examination showed hyponatremia (127 mEq/l). On October 22, marked disturbance of consciousness developed. On October 24, the serum Na level further decreased to 116 mEq/l. On November 8, he was referred to our hospital. On admission, his skin and tongue showed marked dehydration, and severe disturbance of consciousness and neck stiffness were observed. The central venous pressure was 4 cmH2O. In the cerebrospinal fluid, atypical cells were observed, and a diagnosis of meningeal carcinomatosis was made. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was excluded because of marked dehydration, a normal blood ADH level, and because plasma osmotic pressure was greater than urinary osmotic pressure. Considering the possibility of cerebral salt wasting syndrome (CSWS) or hypoadrenocorticism, Na supplementation and drip infusion of prednisolone (20 mg/day) were performed. The serum Na has normalized (140.1 mEq/l), and his consciousness improved. He died of aggravation of the general condition on December 16. Pathological examination demonstrated a small metastatic lesion in the infundibular part of the pituitary gland and a small metastatic lesion in the parenchyma of the bilateral adrenal glands. However, since neither hypotension nor hypoglycemia was observed before treatment, and the blood cortisol level and the serum K level were normal, hypoadrenocorticism was excluded. Hypoaldosteronism was also excluded because of a normal serum K level. CSWS has been reported to be caused by head trauma, subarachnoid hemorrhage, or trans-sphenoidal pituitary operation. This patient is a rare case of CSWS developed in the presence of meningeal carcinomatosis accompanied by a small pituitary metastatic lesion from gastric cancer. The aged with decreased ability to retain water and sodium in the body are more susceptible to CSWS than the young. In the aged with central hyponatremia, the possibility of CSWS should be considered, and early diagnosis and treatment are necessary.

Expression of vascular endothelial growth factor in normal pituitary cells and pituitary adenomas producing adrenocorticotropic hormone

Vascular endothelial growth factor (VEGF) induces endothelial cell proliferation and an increase in capillary permeability. Because the anterior pituitary gland and pituitary adenomas are highly vascular, expression of VEGF was examined immunohistochemically. Some normal pituitary cells stained positively for VEGF, and restaining for ACTH, prolactin, TSH, LH, FSH, and S-100 protein after VEGF staining revealed that almost all cells staining positively for ACTH also stained for VEGF. Only adenomas staining positively for ACTH stained for VEGF. These results suggest that VEGF is produced by normal pituitary cells and adenomas producing ACTH.

Why couldn't an accurate diagnosis be made? An analysis of 1044 consecutive autopsy cases

The protocols of 1044 consecutive patients autopsied between 1983 and 1997 at Sumitomo Hospital (Osaka, Japan) were retrospectively analyzed and the findings were compared with clinical diagnoses. In 73 cases, the clinical diagnosis apparently differed from the autopsy findings, and in six cases the origin of a malignant neoplasm remained unsolved even at autopsy. Of the 73 discrepant cases, 24 were a result of clinician misjudgment and a neglect to conduct further examinations. Missed diagnosis due to an erroneous pathological report, technical error of endoscopy, and misleading results obtained by new non-invasive technologies accounted for seven, nine, and 11 cases, respectively. Twenty-two cases were missed because the clinician could not carry out precise examination. It is concluded that advances in diagnostic technology and medical knowledge have not reduced the value of an autopsy.

Phlebosclerosis of the colon with positive anti-centromere antibody

A 56-year-old woman with symptoms of chronic bowel disease presented a peculiar calcification of the mesenteric vein of the ascending to transverse colon on barium enema study. The resected colon was hard and black. Histo-pathologic examinations demonstrated fibrous change of the colon with a calcified and hyaline-deposited mesenteric vein. No cell infiltration was observed. These findings were compatible with phlebosclerosis and also with systemic sclerosis. Positive anti-centromere antibody and Raynaud's phenomenon, hallmarks of a variant systemic sclerosis, the CREST syndrome were observed. We therefore speculated that the pathogenesis of the phlebosclerosis of the colon is related to the CREST syndrome.

Evaluation of role of mast cells in the development of liver fibrosis using mast cell-deficient rats and mice

BACKGROUND/AIMS

Several studies have suggested that mast cells participate in the development of liver fibrosis in rodent models. In this study mast cell-deficient mutant Ws/Ws rats and W/Wv mice were used to examine whether mast cells are involved in the development of liver fibrosis.

METHODS

Liver fibrosis was induced in rats by bile duct resection (BDR), and by intraperitoneal injections of carbon tetrachloride (CCl4) or porcine serum, and in mice by intragastric administrations of CCl4, and BDR. The degree of fibrosis was evaluated by measuring the hydroxyproline content (microg/mg tissue) of the liver as an index of the collagen content. The density of mast cells (number/cm2 liver section) was determined by counting mast cells in liver sections stained with alcian blue.

RESULTS

In the liver of control non-mutant (+/+) rats, mast cells were found principally in portal areas, and their average density was 200-300/cm2 liver section. BDR, and treatments with CCl4 and porcine serum increased the density of mast cells in the liver of +/+ rats several-fold, and induced liver fibrosis, increasing the liver hydroxyproline content markedly. BDR, and treatments with CCl4 and porcine serum also induced liver fibrosis in Ws/Ws rats, increasing the liver hydroxyproline content to a similar or higher level than that in +/+ rats. However, the average densities of mast cells in the liver of Ws/Ws rats after BDR and treatment with CCl4 and porcine serum were at most 10.2/cm2 liver section. The density of mast cells in the liver of control +/+ mice was extremely low (average, less than 2), and neither BDR nor treatment with CCl4 caused any significant increase in their density, whereas these treatments induced liver fibrosis and markedly increased the liver hydroxyproline content. Furthermore, treatment with CCl4 induced fibrosis in the liver of W/Wv mice similarly to that in +/+ mice, but the density of mast cells in the liver of W/Wv mice was very low (average, less than 1), and was not increased by treatment with CCl4.

CONCLUSIONS

The present results indicate that mast cells play no role in the development of liver fibrosis in rats and mice.

Limb and skin abnormalities in mice lacking IKKalpha

The gene encoding inhibitor of kappa B (IkappaB) kinase alpha (IKKalpha; also called IKK1) was disrupted by gene targeting. IKKalpha-deficient mice died perinatally. In IKKalpha-deficient fetuses, limb outgrowth was severely impaired despite unaffected skeletal development. The epidermal cells in IKKalpha-deficient fetuses were highly proliferative with dysregulated epidermal differentiation. In the basal layer, degradation of IkappaB and nuclear localization of nuclear factor kappa B (NF-kappaB) were not observed. Thus, IKKalpha is essential for NF-kappaB activation in the limb and skin during embryogenesis. In contrast, there was no impairment of NF-kappaB activation induced by either interleukin-1 or tumor necrosis factor-alpha in IKKalpha-deficient embryonic fibroblasts and thymocytes, indicating that IKKalpha is not essential for cytokine-induced activation of NF-kappaB.

A critical role for a peritumoral stromal reaction in the induction of T-cell migration responsible for interleukin-12-induced tumor regression

Interleukin (IL) 12 has been shown to elicit tumor regression when this cytokine induces the migration of T cells to tumor sites. The present study investigates the role of a peritumoral stromal reaction in IL-12-induced T-cell migration. In the CSA1M and OV-HM tumor models, IL-12 treatment induced tumor regression that is associated with T-cell migration. Neither T-cell migration nor tumor regression was observed in the Meth A and MCH-1-A1 models. Stromal tissue containing neovascular blood vessels developed at the peritumoral area of the former two IL-12-responsive tumors but not at the peritumoral area of the latter two IL-12-unresponsive tumors. The significance of stroma development was investigated using a pair of tumor models (CSA1M and a subline derived from CSA1M designated the CSA1M variant), both of which exhibit the same tumor immunogenicity. In contrast to the parental CSA1M cell line, the variant cell line was not responsive to IL-12, and neither stroma development nor T-cell migration was observed, even after IL-12 treatment. Histological analyses revealed that the parental cell line had peritumoral stroma with intrastromal vessels but only a few vessels in tumor parenchyma, whereas the variant cell line showed no stroma but had abundant vasculature in the tumor parenchyma. Most importantly, only stromal vessels in the parental tumors expressed detectable and enhanced levels of vascular cell adhesion molecule 1 (VCAM-1)/ intercellular adhesion molecule 1 (ICAM-1) before and after IL-12 treatment, respectively. In contrast, parenchymal vasculature in the variant cell line failed to express VCAM-1/ICAM-1 even after IL-12 treatment. When transferred into recipient tumor-bearing mice, IL-12-stimulated T cells from the parental CSA1M-bearing or the variant CSA1M-bearing mice migrated into the parental but not into the variant tumor mass. Together with our previous finding that T-cell migration depends on the VCAM-1/ICAM-1 adhesive interactions, the present results indicate a critical role for peritumoral stroma/stromal vasculature in the acceptance of tumor-infiltrating T cells that is a prerequisite for IL-12-induced tumor regression.

Role of c-kit receptor tyrosine kinase in development of oval cells in the rat 2-acetylaminofluorene/partial hepatectomy model

Oval cells that develop in the rat 2-acetylaminofluorene/partial hepatectomy (AAF/PH) model express the c-kit receptor tyrosine kinase (KIT) and its ligand, stem cell factor (SCF). We investigated the role of the SCF/KIT system in the development of oval cells using Ws/Ws rats, whose c-kit kinase activity was severely impaired owing to a small deletion in the kinase domain. On days 7, 9, and 13 after PH in the AAF/PH model, the development of oval cells was remarkably suppressed in Ws/Ws rats when compared with that of the control normal (+/+) rats. However, oval cells that developed in Ws/Ws rats expressed marker proteins of oval cells, such as alpha-fetoprotein (AFP), cytokeratin-19 (CK-19), and flt-3 receptor tyrosine kinase, similar to those of +/+ rats. Furthermore, labeling with [3H]-thymidine and immunostaining of Ki-67 showed that the proliferative activity of oval cells that developed in Ws/Ws rats was comparable with that of +/+ rats. The present results indicate that the signal transduction of the SCF/KIT system plays a crucial role in the development of oval cells, at least, in the rat AAF/PH model, and suggest that KIT-mediated signal transduction plays only a small role in determining the phenotype and in the proliferative activity of oval cells.

Activating mutation in the catalytic domain of c-kit elicits hematopoietic transformation by receptor self-association not at the ligand-induced dimerization site

The c-kit receptor tyrosine kinase (KIT) is constitutively activated by naturally occurring mutations in either the juxtamembrane domain or the kinase domain. Although the juxtamembrane domain mutations led to ligand-independent KIT dimerization, the kinase domain mutations (Asp814 --> Val or Tyr) did not. In an effort to determine if the kinase domain mutant could transfer oncogenic signaling without receptor dimerization, we have constructed the truncated types of c-kitWild and c-kitTyr814 cDNAs (c-kitDel-Wild and c-kitDel-Tyr814 cDNAs, respectively), in which ligand-binding and ligand-induced dimerization domains were deleted. When c-kitDel-Wild and c-kitDel-Tyr814 genes were introduced into a murine interleukin-3 (IL-3)-dependent cell line Ba/F3, KITDel-Tyr814 was constitutively phosphorylated on tyrosine and activated, whereas KITDel-Wild was not. In addition, Ba/F3 cells expressing KITDel-Tyr814 (Ba/F3(Del-Tyr814)) grew in suspension culture without the addition of exogenous growth factor, whereas Ba/F3 cells expressing KITDel-Wild (Ba/F3(Del-Wild)) required IL-3 for growth. The factor-independent growth of Ba/F3(Del-Tyr814) cells was virtually abrogated by coexpression of KITW42 that is a dominant-negative form of KIT, but not by that of KITWild, suggesting that KITDel-Tyr814 may not function as a monomer but may require receptor dimerization for inducing factor-independent growth. Furthermore, KITDel-Tyr814 was found to be coimmunoprecipitated with KITWild or KITW42 by an ACK2 monoclonal antibody directed against the extracellular domain of KIT. Moreover, KITW42 was constitutively associated with a chimeric FMS/KITTyr814 receptor containing the ligand-binding and receptor dimerization domain of c-fms receptor (FMS) fused to the transmembrane and cytoplasmic domain of KITTyr814, but not with a chimeric FMS/KITWild receptor even after stimulation with FMS-ligand. These results suggest that constitutively activating mutation of c-kit at the Asp814 codon may cause a conformation change that leads to receptor self-association not in the extracellular domain and that the receptor self-association of the Asp814 mutant may be important for activation of downstream effectors that are required for factor-independent growth and tumorigenicity.

Peritoneal serous papillary carcinoma: radiological appearance

BACKGROUND

The radiological appearance of peritoneal serous papillary carcinoma (PSPC) is described.

METHODS

Three cases of PSPC were analyzed retrospectively with regard to the radiological appearance and histopathological features.

RESULTS

All three patients were women, aged 44-71 years. Massive ascites and a greater omentum tumor were observed on computed tomography in all patients. Double-contrast enema performed in one patient showed irregularity on the upper aspect of the transverse colon. Radiological examinations excluded primary tumors in both gastrointestinal and genital organs in all patients. Histological diagnosis was made from the surgical specimen in two patients and from an autopsy specimen in one patient. All patients had a large omental tumor involving the transverse colon, but the ovaries were not involved or only minimally involved on the surface. Serum CA125 was markedly elevated, and immunohistochemical staining for CA125 was positive within the tumor cell cytoplasm in all three patients.

CONCLUSION

PSPC cannot be diagnosed from radiological findings alone because of its similarity to metastatic peritoneal carcinomatosis and peritoneal mesothelioma. Marked elevation of serum CA125 may help with PSPC diagnosis. Response to treatment is promising, and exploratory laparotomy is thus justified when a patient shows characteristic radiological findings and high CA125 level.

Enhanced Th1 activity and development of chronic enterocolitis in mice devoid of Stat3 in macrophages and neutrophils

We have generated mice with a cell type-specific disruption of the Stat3 gene in macrophages and neutrophils. The mutant mice are highly susceptible to endotoxin shock with increased production of inflammatory cytokines such as TNF alpha, IL-1, IFN gamma, and IL-6. Endotoxin-induced production of inflammatory cytokines is augmented because the suppressive effects of IL-10 on inflammatory cytokine production from macrophages and neutrophils are completely abolished. The mice show a polarized immune response toward the Th1 type and develop chronic enterocolitis with age. Taken together, Stat3 plays a critical role in deactivation of macrophages and neutrophils mainly exerted by IL-10.

Targeted disruption of ATF4 discloses its essential role in the formation of eye lens fibres

BACKGROUND

Activating transcription factor-4 (ATF4)--also termed CREB2, C/ATF, and TAXREB67--is a basic-leucine zipper (bZip) transcription factor that belongs to the ATF/CREB family. In addition to its own family members, ATF4 can also form heterodimers with other related but distinct bZIP proteins such as the C/EBP, AP-1 and Maf families, which may give rise to a variety of combinatorial diversity in gene regulation. In order to assess the in vivo essential role of ATF4, we have generated mice lacking ATF4 by gene targeting.

RESULTS

ATF4-deficient mice exhibited severe microphthalmia. Although ATF4-deficient eyes revealed a normal gross lens structure up to embryonic day 14.5, later on the ATF4-deficient lens, degenerated due to apoptosis without the formation of lens secondary fibre cells. Retinal development was normal in the mutant mice. The lens-specific expression of ATF4 in the mutant mice led not only to the recovery of lens secondary fibres but also to the induction of hyperplasia of these fibres.

CONCLUSION

These results demonstrated that ATF4 is essential for the later stages of lens fibre cell differentiation.

Ovarian fibroma of high signal intensity on T2-weighted MR image

It has been reported that ovarian fibromas display low signal intensity on both T1- and T2-weighted magnetic resonance images. We report an ovarian fibroma exhibiting low signal intensity on a T1-weighted image and high signal intensity on a T2-weighted image. Microscopically pronounced myxomatous changes were shown in the fibroma. The signal intensity of ovarian fibromas differs with the degree of myxomatous change.

Expression of cytokines enhancing the osteoclast activity, and parathyroid hormone-related protein in prostatic cancers before and after endocrine therapy: an immunohistochemical study

Cytokines, interleukin (IL)-1alpha, IL-1beta, IL-3, IL-6, macrophage colony stimulating factor (M-CSF) and tumor necrosis factor-alpha (TNF-alpha) as well as parathyroid hormone-related protein (PTHrP) have been shown to enhance the osteoclast activity. To investigate mechanisms of the development of bone metastasis of prostatic cancers, expression of these cytokines and PTHrP was examined immunohistochemically in prostatic cancers of patients administered no prior therapy or endocrine therapy. All cytokines and PTHrP were stained in the cytoplasm of the epithelium of non-cancerous prostatic glands, and IL-3 and IL-6 were stained in the cytoplasm of smooth muscle cells besides epithelial cells of non-cancerous prostatic glands. Incidences of positivity of staining in prostate cancers of patients administered no prior therapy were 100% for IL-1alpha, IL-1beta, IL-6, M-CSF and TNF-alpha, 20% for IL-3, and 80% for PTHrP. Incidence of prostatic cancers stained positively for IL-1alpha and IL-1beta decreased significantly in patients administered endocrine therapy, but those for IL-3, IL-6, M-CSF, TNF-alpha and PTHrP did not change significantly. The present results suggest that prostatic cancers produce various cytokines, IL-1alpha, IL-1beta, IL-3, IL-6, M-CSF and TNF-alpha, as well as PTHrP, and that expression of these cytokines and PTHrP except IL-1alpha and IL-1beta is not under androgen control. Cytokines and PTHrP produced by prostatic cancers may play a role in the development of bone metastasis of prostatic cancers.

Later onset of apoptosis in the bulbourethral glands after castration compared to that in the seminal vesicles

Androgens affect many different target organs within the male reproductive tract to stimulate their development and secretory cytodifferentiation, and to maintain structure and function in adulthood. Castration causes regression of these organs via apoptosis. However, not all organs of the reproductive tract are equally sensitive to androgen withdrawal. The effects of castration on the mouse seminal vesicles (SVs) and bulbourethral glands (BUGs) were compared in terms of protein and DNA contents, epithelial apoptosis, and proliferative response of epithelial cells to androgen. Castration induced similar, marked decreases in protein contents in the SV and BUG by 2 days after castration which reached a minimum at 16 days post castration. Both organs underwent a decrease in DNA content, but the kinetics of this decline differed. In the SV, DNA content was significantly decreased by 4 days whereas in the BUG this did not occur until 16 days post castration. By day 16 both organs had regressed to roughly the same degree. The apoptotic index in the epithelium reflected this difference in timing as well. Apoptotic index of the SV epithelium was highest on day 3 after castration and declined thereafter. On the other hand, the apoptotic index in the BUG didn't begin to increase until 7 days after castration and became maximal on day 12. Daily injections of testosterone propionate (TP) from day 8, 16, or 30 after castration all increased epithelial labelling index in the SVs to a similar degree. However, the TP-induced increase in the epithelial labelling index in the BUG beginning on day 8 after castration was considerably less than that in BUGs receiving TP treatment from day 16 or 30 after castration. Thus, the proliferative response of the epithelium depended upon prior apoptosis in the gland, with the timing being delayed in the BUG as compared with the SV. The present results indicate that castration induces epithelial apoptosis and reduction in glandular DNA content considerably later in the BUG than in the SV though reduction in protein content in the BUG fell simultaneously with that in the SV.

A case of acute interstitial pneumonia indistinguishable from bronchiolitis obliterans organizing pneumonia/cryptogenic organizing pneumonia: high-resolution CT findings and pathologic correlation

We report a case of histologically proved acute interstitial pneumonia (AIP) with subacute onset whose high-resolution CT (HRCT) findings were indistinguishable from those of bronchiolitis obliterans organizing pneumonia (BOOP)/cryptogenic organizing pneumonia (COP). The HRCT findings were air-space consolidation with air-bronchiologram associated with little ground-glass attenuation, and nodules. Some cases of AIP present HRCT findings indistinguishable from those of BOOP/COP.

Multiple roles of interferon-gamma in the mediation of interleukin 12-induced tumor regression

Administration of recombinant interleukin 12 (IL-12) induces tumor regression that is associated with T-cell infiltration in the OV-HM ovarian carcinoma and CSA1M fibrosarcoma models. After confirming the blocking of regression by injection of anti-IFN-gamma monoclonal antibody (mAb), we investigated the mechanisms underlying the requirement of IFN-gamma in T-cell migration and tumor regression. T-cell migration was inhibited by injection of anti-IFN-gamma mAb to OV-HM tumor-bearing mice prior to IL-12 treatment. We examined, using the lymphoid cell migration assay, whether IFN-gamma is required for enhancing the migratory capacity of T cells or the T cell-accepting potential of tumor masses during IL-12 treatment. Spleen cells from IL-12-treated or untreated OV-HM-bearing mice were stained in vitro with a fluorescein chemical and transferred i.v. into OV-HM-bearing mice that were not treated with IL-12. Migration of donor cells was quantitated by counting the number of fluorescent cells on cryostat sections of tumor masses from recipient mice. Compared to spleen cells from OV-HM-bearing mice that were not treated with IL-12, enhanced migration was observed for cells from IL-12-treated OV-HM-bearing mice. Anti-IFN-gamma pretreatment of donor mice before IL-12 treatment did not reduce the migratory capacity of T cells, whereas migration was markedly inhibited in recipient mice injected with anti-IFN-gamma. Anti-IFN-gamma pretreatment decreased vascular cell adhesion molecule-1 (VCAM-1)-/intercellular adhesion molecule-1 (ICAM-1)-positive blood vessels at tumor sites. Consistent with this, migration was also inhibited by treatment of recipient mice with either anti-VCAM-1 or anti-ICAM-1 mAb. In contrast to the OV-HM model, T-cell migration was not affected in the CSA1M model following preinjection of anti-IFN-gamma mAb. In this model, VCAM-1-/ICAM-1-positive blood vessels existed even after anti-IFN-gamma treatment, although tumor regression was completely inhibited. These results indicate that IFN-gamma plays two distinct roles in expressing the antitumor efficacy of IL-12: one is to support the T-cell acceptability of tumor masses, and the other is to mediate the antitumor effects of migrated T cells.

Expression of c-kit and stem cell factor mRNA in liver specimens from healthy adult dogs

OBJECTIVE

To determine expression of c-kit and stem cell factor (SCF) mRNA in liver specimens from healthy adult dogs and to investigate whether differentiation of mast cells in the liver of dogs is supported by the c-kit receptor tyrosine kinase/SCF system.

ANIMALS

3 healthy adult Beagles.

PROCEDURE

The nucleic acid sequence of the canine c-kit fragment of the intracellular tyrosine kinase domain was determined. Magnitudes of c-kit and SCF mRNA expression in liver samples was determined by means of northern blot analysis, using probes based on canine sequences. To determine which cells were expressing c-kit and SCF mRNA, in situ hybridization was performed.

RESULTS

Expression of c-kit and SCF mRNA in liver samples was weak but appreciable. In situ hybridization revealed that c-kit and SCF mRNA expression was restricted to mast cells and plasma cells, respectively.

CONCLUSION

Expression of SCF mRNA was detected in liver from healthy adult dogs. The c-kit receptor tyrosine kinase/SCF system may, possibly in combination with other growth factor and receptor systems, be involved in proliferation and differentiation of liver mast cells in dogs.

Incidence of prostatic intra-epithelial neoplasia in Osaka, Japan

High-grade prostatic intra-epithelial neoplasia (HGPIN) is the most likely precancerous lesion for prostatic carcinoma. A high incidence of its association with cancer has been reported in Western countries. On the other hand, information regarding its incidence is limited in Japan, where the mortality due to prostate cancer is much lower. We reviewed 53 clinical stage T2 or T3 prostatic cancers of Japanese patients living in Osaka, Japan (mean age, 67.2 years). These cases were subdivided into a pre-operatively non-castrated group (34 cases) and a medically or surgically castrated group (19 cases). HGPIN was found in 27 cases. The incidence of HGPIN was significantly lower in the castrated group (21.0%) compared with the non-castrated group (67.6%). In the non-castrated group, patient age, pathological stage, Gleason score, tumor size and serum prostate-specific antigen showed no significant correlation with HGPIN. Advanced pathological stage and tumor size tended to decrease the incidence of HGPIN, although this was not statistically significant. When the study group was limited to stage T2 tumors of the non-castrated group, the incidence of HGPIN was 81.0%. HGPIN in Japan may also be clinically and etiologically significant as a precursor of clinical cancer.

Alterations of the p53 gene in occupational bladder cancer in workers exposed to aromatic amines

Epidemiologic studies have revealed an increased risk for development of transitional cell carcinoma (TCC) among dye workers/painters occupationally exposed to aromatic amines such as benzidine, beta-naphthylamine, orthotoluidine, and aniline. In the present study, p53 gene mutations in 26 patients with bladder lesions occupationally exposed to aromatic amines were examined by single-strand conformation polymorphism analysis of PCR-amplified DNA segments, followed by direct sequencing. All were male, and age at admission ranged from 43 to 75 (median 66) years. Twenty-nine biopsy specimens were from primary lesions; 17 (61%) of these lesions were from TCC including one carcinoma in situ (CIS); 11 were from dysplasia; and 1 was taken from normal-looking transitional epithelium adjoining TCC. TCC lesions included 12 with low-grade (Grade 1 or 2) and 5 with high-grade (Grade 3 or CIS) changes. Twenty-four recurrent lesions were biopsied in 16 patients: TCC was found in 12 lesions (50%), CIS in 1 (4%), and dysplasia in 11 (46%). All lesions were localized within the submucosa except for two, which invaded into the muscle layers. PCR-single-strand conformation polymorphism analysis demonstrated that mutations (a) occurred in both dysplasia and in normal-looking epithelium, in addition to TCC lesions; (b) were at different sites in the p53 gene in concurrent or metachronous lesions; and (c) occurred in exon 5 in approximately 70% of lesions, especially at codons 151 and 152. C to T transitions were predominantly seen. These findings clearly show differences in the pattern of p53 mutation in occupational versus nonoccupational bladder lesions. Because both common and unique point mutations were found in p53 in concurrent and metachronous lesions, our results suggest that the multifocality of occupational bladder cancer arises both from multiple clonal lesions (field change) and from the dissemination of a single clone.

The Relation between Superoxide Dismutase in Cancer Tissue and Clinico-pathological Features in Breast Cancer

The localization of Cu/Zn- and Mn-superoxide dismutase (SOD) in breast cancer tissue (12 papillotubular carcinomas, 21 solid-tubular carcinomas, 16 scirrhous carcinomas, 1 medullary carcinoma, 1 secreting carcinoma, 1 lobular carcinoma, 1 Paget's disease) was investigated via an immunohistochemical technique using antihuman Cu/Zn- and Mn-SOD antibodies in 10%formalin fixed-paraffin embedded thin sections. Both SODs stained strongly in the normal breast gland, but not clearly in many cancer tissues. Furthermore, Cu/Zn-SOD stained more strongly in well differentiated tubular carcinomas than in poorly differentiated tubular carcinomas. It tended to stain less in tumors which recurred or had a poor outcome, and in tumors with a diploid pattern on DNA flow cytometry. Mn-SOD staining was similar to that of Cu/Zn-SOD, but no significant differences among subgroups was found, since the incidence of positively staining tumors was too small in all groups. The intensity of SOD staining seems to change in relation to cell proliferation and differentiation in breast carcinoma, and may be a prognostic indicator, since SOD decreased in poorly differentiated carcinoma and in tumors which developed distant metastasis. Thus, the localization of SOD in breast cancer tissue can provide useful information for cancer treatment.

Abnormal expression of mouse mast cell protease 5 gene in cultured mast cells derived from mutant mi/mi mice

Mast cells contain a lot of mast cell-specific proteases. We have reported that the expression of mouse mast cell protease 6 (MMCP-6) is remarkably reduced in both cultured mast cells (CMCs) and skin mast cells of mi/mi mutant mice. In the present study, we found that the expression of MMCP-5 was reduced in CMCs but not in skin mast cells of mi/mi mice, and we compared the regulation mechanisms of MMCP-5 with those of MMCP-6. The mi locus encodes a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors (hereafter called MITF). The consensus sequence recognized and bound by bHLH-Zip transcription factors is CANNTG. The overexpression of the normal (+) MITF but not of mi-MITF normalized the poor expression of the MMCP-5 gene in mi/mi CMCs, indicating the involvement of +-MITF in transactivation of the MMCP-5 gene. Although +-MITF directly bound CANNTG motifs in the promoter region of the MMCP-6 gene and transactivated it, the binding of +-MITF to the CAGTTG motif in the promoter region of the MMCP-5 gene was not detectable. The +-MITF appeared to regulate the transactivation of the MMCP-5 gene indirectly. Moreover, addition of stem cell factor to the medium normalized the expression of the MMCP-5 but not of the MMCP-6 gene in mi/mi CMCs. Despite the significant reduction of both MMCP-5 and MMCP-6 expressions in mi/mi CMCs, their regulation mechanisms appeared to be different.

IL-12-induced tumor regression correlates with in situ activity of IFN-gamma produced by tumor-infiltrating cells and its secondary induction of anti-tumor pathways

Administration of recombinant interleukin-12 (rIL-12) into CSA1M fibrosarcoma-bearing mice results in complete regression of growing tumors. This tumor regression is associated with massive lymphoid cell infiltration to tumor sites and is completely blocked by injection of anti-interferon-gamma (IFN-gamma) monoclonal antibody (mAb). We investigated whether anti-IFN-gamma mAb exerts its suppressive effect on tumor regression by blocking the IL-12-induced lymphoid cell migration to tumor sites or by inhibiting the secondary effects of IFN-gamma produced by infiltrating cells. Injection of anti-IFN-gamma mAb to CSA1M-bearing mice before IL-12 treatment prevented the induction of tumor regression, whereas this treatment affected only marginally the infiltration of lymphoid cells to tumor masses. In accordance with this, IFN-gamma mRNA was expressed inside tumor masses by infiltrating cells after IL-12 therapy irrespective of whether anti-IFN-gamma mAb was injected. However, anti-IFN-gamma mAb treatment almost completely abrogated the in situ expression of inducible nitric oxide synthase (iNOS) as well as IFN-inducible protein-10 (IP-10) genes as examples of IFN-gamma-inducible genes. Immunohistochemical analyses also revealed that the expression of iNOS protein was completely inhibited by anti-IFN-gamma injection. These results suggest that the implementation of in situ IFN-gamma activity and its secondary induction of anti-tumor pathways such as iNOS and IP-10 expression are important processes in the IL-12-induced tumor regression.

Involvement of transcription factor encoded by the mouse mi locus (MITF) in expression of p75 receptor of nerve growth factor in cultured mast cells of mice

The mi locus of mice encodes a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors (hereafter called MITF). Cultured mast cells (CMCs) of mi/mi genotype showed a poor response to nerve growth factor (NGF). Addition of NGF to the suboptimal dose of interleukin-3 (IL-3) increased the plating efficiency of normal (+/+) CMCs but not mi/mi CMCs. Although +/+ CMCs were berberine sulfate-negative when cultured with IL-3, +/+ CMCs became berberine sulfate-positive when cultured in the presence of both IL-3 and NGF, which suggested increased heparin content. In contrast, NGF did not influence the phenotype of mi/mi CMCs. The poor response of mi/mi CMCs to NGF was attributed to the deficient expression of p75 NGF receptor. The purpose of the present study is to examine the effect of MITF on p75 gene transcription. Overexpression of +-MITF or mi-MITF was observed in mi/mi CMCs to which cDNA encoding each type of MITF had been introduced using the retroviral vector. Overexpression of +-MITF but not of mi-MITF normalized the expression of p75 and the above-mentioned poor responses of mi/mi CMCs to NGF, indicating the involvement of +-MITF in p75 gene transactivation. Then, we analyzed the promoter of the p75 gene. Two CANNTG motifs recognized by bHLH-Zip-type transcription factors were conserved between the mouse and rat p75 promoters. One of these two CANNTG motifs was specifically bound by +-MITF. When the luciferase gene under the control of the p75 promoter was cotransfected into NIH/3T3 fibroblasts with cDNA encoding +-MITF or mi-MITF, luciferase activity increased significantly only when +-MITF cDNA was cotransfected. The mutation of this CANNTG motif abolished the transactivation effect of +-MITF, indicating that +-MITF transactivated the p75 gene, at least in part, through direct binding.

Involvement of transcription factor encoded by the mouse mi locus (MITF) in apoptosis of cultured mast cells induced by removal of interleukin-3

Mast cells develop when spleen cells of mice are cultured in the medium containing interleukin (IL)-3. Cultured mast cells (CMCs) show apoptosis when they are incubated in the medium without IL-3. We obtained CMCs from tg/tg mice that did not express the transcription factor encoded by the mi gene (MITF) due to the integration of a transgene at its 5' flanking region. MITF is a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors. We investigated the effect of MITF on the apoptosis of CMCs after removal of IL-3. When cDNA encoding normal MITF ((+)-MITF) was introduced into tg/tg CMCs with the retroviral vector, the apoptosis of tg/tg CMCs was significantly accelerated. The mutant mi allele represents a deletion of an arginine at the basic domain of MITF. The apoptosis of tg/tg CMCs was not accelerated by the introduction of cDNA encoding mi-MITF. The overexpression of (+)-MITF was not prerequisite to the acceleration of the apoptosis, as the apoptotic process proceeded faster in +/+ CMCs than in mi/mi CMCs. The Ba/F3 lymphoid cell line is also dependent on IL-3, and Ba/F3 cells show apoptosis after removal of IL-3. The c-myc gene encodes another transcription factor of the bHLH-Zip family, and the overexpression of the c-myc gene accelerated the apoptosis of Ba/F3 cells. However, the overexpression of (+)-MITF did not accelerate the apoptosis of Ba/F3 cells. The (+)-MITF appeared to play some roles for the acceleration of the apoptosis specifically in the mast cell lineage.

Expression of Fas and Fas ligand in the testes and testicular germ cell tumors: an immunohistochemical study

The Fas-Fas ligand system plays a crucial role in the production of a signal for apoptosis in the immune system. In the present study, expression of Fas and Fas ligand in the testes and testicular germ cell tumors was examined immunohistochemically. Expression of both Fas and Fas ligand was found on Leydig cells, Sertoli cells, and germ cells in the testis, and on epithelial cells in the epidydimal duct. Expression of both Fas and Fas ligand was also found in all 23 seminomas, 8 embryonal carcinomas, and 3 yolk sac tumors which were examined in this study. Western blot analysis after sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis under a reducing condition with tissues of the thymus, the testis, and a seminoma showed a single major band bound to the antibody for Fas or Fas ligand at the position of molecular weight slightly more than 47.5 kilodalton. Since both Fas and Fas ligand are expressed on normal testicular cells, and on cells of testicular germ cell tumors, the Fas-Fas ligand system in these cells seems to play a role other than producing a signal for apoptosis.

Effects of prolactin and estrogen on cell proliferation of the mouse liver induced by partial hepatectomy

Estrogen or prolactin suppresses mouse hepatocellular tumorigenesis induced by carcinogens through inhibition of the growth of preneoplastic hepatocytes. In the present study, we investigated whether estrogen or prolactin inhibits proliferation of normal hepatocytes as well as preneoplastic hepatocytes in mice. The proliferation of mouse hepatocytes was induced by partial hepatectomy, and DNA synthesis of the liver was evaluated by measurement of 5-[125I]iododeoxyuridine ([125I]IdUrd) uptake/mg liver DNA after an injection of [125I]IdUrd into mice. For acute treatment with estrogen or prolactin, estradiol-17 beta (E2) (1 micrograms) or ovine prolactin (140 micrograms) was injected into ovariectomized mice twice a day from the day of partial hepatectomy. For chronic treatment with estrogen, ovariectomized mice received implants of E2 pellets containing 100 micrograms E2 40 days before partial hepatectomy, and for chronic treatment with prolactin, hyperprolactinemia was induced by pituitary graft under the renal capsule of ovariectomized mice 40 days before partial hepatectomy or by daily injections of perphenazine (150 micrograms/day) beginning 40 days before partial hepatectomy. The acute treatment with either estrogen or prolactin did not affect the hepatocyte proliferation induced by partial hepatectomy. Chronic hyperprolactinemia induced by the pituitary graft or by injections of perphenazine, and the chronic treatment with E2 pellets did not suppress either basal or partial hepatectomy-induced proliferation of hepatocytes. The present results show that acute and chronic treatments with estrogen or prolactin do not inhibit proliferation of mouse normal hepatocytes, and suggest that the effects of estrogen and prolactin on proliferation of mouse hepatocytes are different from those on proliferation of preneoplastic hepatocytes.

Preclinical Cushing's syndrome due to adrenocorticotropin-independent bilateral adrenocortical macronodular hyperplasia with concurrent excess of gluco- and mineralocorticoids

A 48-year-old with bilateral adrenal incidentalomas was studied. Although the serum cortisol level was normal, autonomous cortisol secretion was shown by the loss of diurnal rhythm, no suppressibility by dexamethasone, and complete suppression of plasma adrenocorticotropin levels. Imaging analyses revealed bilateral adrenal masses, showing isotope uptake. He was diagnosed as preclinical Cushing's syndrome due to adrenocorticotropin-independent bilateral adrenocortical macronodular hyperplasia, confirmed histologically. Despite the undetectable plasma adrenocorticotropin level and renin activity, serum mineralocorticoids levels were not suppressed, which were decreased after subtotal adrenalectomy. It was suggested that hyperplastic adrenal glands could produce both gluco- and mineralocorticoids concomitantly.

Molecular cloning of cDNA encoding the c-kit receptor of Shiba goats and a novel alanine insertion specific to goats and sheep in the kinase insert region

The complete open reading frame (ORF) of the c-kit cDNA was cloned from a cerebellar cDNA library of the Shiba goat (Capra hircus var Shiba) with the dominant black-eyed white phenotype. The analysis of the deduced amino acid sequence revealed the presence of a single amino acid insertion (alanine) in the kinase insert (KI) region. While the newly found alanine insertion is not correlated with the coat color phenotype of goats, it appears to be characteristic of the c-kit genes in goats and sheep. Although the biological significance of the insert remains to be investigated, its phylogenetically limited distribution will provide us with a useful and interesting tool to analyze the problems of evolution of sheep and goats in bovidae.

Mechanisms of constitutive activation of c-kit receptor tyrosine kinase

We investigated the mechanism of constitutive activation of c-kit receptor tyrosine kinase (KIT) found in the FMA3 murine mastocytoma cell line, and compared it with the mechanisms observed in other tumor mast cell lines (the HMC-1 human mast cell leukemia cell line, the RBL-2H3 rat mast cell leukemia cell line, and the P-815 murine mastocytoma cell line). The c-kit gene obtained from FMA3 cells was found to have 21-base deletion at the juxtamembrane domain of KIT, thereby leading to the constitutive activation of KIT. The deletion at the juxtamembrane domain resulted in constitutive dimerization of c-kit proteins, whereas the point mutation that were detected at the kinase domain of KIT in HMC-1, RBL-2H3, and P-815 cells caused constitutive activation of KIT without dimerization. These constitutively activating mutations of c-kit may play a role in development of mast cell tumors.

Role of c-kit receptor tyrosine kinase in the development, survival and neoplastic transformation of mast cells

The c-kit gene is allelic with the dominant spotting (W) locus on mouse chromosome 5 and encodes a receptor tyrosine kinase. The ligand for c-kit receptor is stem cell factor (SCF), which is the principal growth factor for mast cells. The loss-of-function mutations of c-kit receptor affect the development of mast cells, thereby resulting in a depletion of mast cells. The abundant expression of c-kit receptor is indispensable for the survival of mast cells. In addition, the gain-of-function mutations of c-kit receptor were found in several tumor mast cell lines. When these gain-of-function mutations were introduced to cells of murine interleukin (IL)-3-dependent cell lines, the expression of c-kit receptor with constitutive tyrosine kinase activity not only abrogated the IL-3 requirement of the cells, but also caused them to become tumorigenic in nude athymic mice. The gain-of-function mutations of c-kit receptor appear to result in the malignant transformation of mast cells. Taken together, the signals from the c-kit receptor are essential for the development, survival, and malignant transformation of mast cells.