Gli1+-PDL Cells Contribute to Alveolar Bone Homeostasis and Regeneration

The periodontal ligament (PDL) contains mesenchymal stem cells (MSCs) that can differentiate into osteoblasts, cementoblasts, and fibroblasts. Nevertheless, the distribution and characteristics of these cells remain uncertain. Gli1, an essential hedgehog signaling transcription factor, functions in undifferentiated cells during embryogenesis. Therefore, in the present study, the differentiation ability of Gli1⁺ cells was examined using Gli1-CreERT2/ROSA26-loxP-stop-loxP-tdTomato (iGli1/Tomato) mice. In 4-wk-old iGli1/Tomato mice, Gli1/Tomato⁺ cells were only slightly detected in the PDL, around endomucin-expressing blood vessels. These cells had proliferated over time, localizing in the PDL as well as on the bone and cementum surfaces at day 28. However, in 8-wk-old iGli1/Tomato mice, Gli1/Tomato⁺ cells were quiescent, as most cells were not immunoreactive for Ki-67. These cells in 8-wk-old mice exhibited high colony-forming unit fibroblast activity and were capable of osteogenic, chondrogenic, and adipogenic differentiation in vitro. In addition, after transplantation of teeth of iGli1/Tomato mice into the hypodermis of wild-type mice, Tomato fluorescence indicating the progeny of Gli1⁺ cells was detected in the osteoblasts and osteocytes of the regenerated bone. These results demonstrate that Gli1⁺ cells in the PDL were MSCs and could contribute to the alveolar bone regeneration.

Abstract P6-11-17: Nanoparticle albumin-bound paclitaxel-induced peripheral neuropathy in patients receiving neoadjuvant or adjuvant chemotherapy for breast cancer

A brief background discussion.

Nanoparticle albumin-bound paclitaxel (nab-PTX) has been developed under the concept of improved drug delivery. nab-PTX has been shown to significantly increase progression-free survival compared with solvent-based paclitaxel (PTX) in metastatic breast cancer. However, the long-term outcomes of nab-PTX induced peripheral neuropathy (nPIPN) have not yet been fully elucidated.

Trial design: observational cohort study (UMIN20852)

Primary objective: The long-term outcome of nPIPN

Secondary objectives

(1)The validity of the Neuropathic Pain Screening Questionnaire (Japan–Q, Ishikawa et al. Pain Research 2016 )

(2) To evaluate the effect of frozen gloves and elastic stockings for nPIPN

nPIPN was assessed by the Japan-Q (J-Q) and Common Toxicity Criteria for Adverse Events ver 4.0 (CTC). The J-Q is an assessment tool for patient-reported pain severity, which consists of seven items, each rated on a five-point scale 0-4; grade 0 (no symptoms) to grade 4 (verysevere symptoms). Pricking pain, electric shock pain, burn like pain, tingling pain with numbness, allodynia, reduced or hyper sensitivity and hand-foot syndrome. Assessment was performed every day during chemotherapy, six months and one year after completion of nab-PTX therapy. Total of 28 points for each day and 588 points for each cycle, higher point correlates with severity. Frozen gloves during administration of nab-PTX and/or elastic stockings were optionally used.

Statistical methods

Kruskal Wallis test was used and p<0.05 was considered as significant.

RESULTS:

Between May 2013, and April 2016, 105 patients were enrolled from 7 hospitals. In 73 patients (69.5%) nab-PTX was administered as primary and in 32 patients (30.5%) as adjuvant therapy. Forty three (41.0%) patients received nab-PTX as first line and 62 (59.0%) received after anthracycline contained regimen. Trastuzumab was administered as combination therapy with nab-PTX for Her2 positive patients. Both frozen gloves and stockings were used in 21 patients (20.0%) and frozen gloves only were used in 21 patients (20.0%) according to patient preference.

One hundred patients (95.2%) completed four courses, and overall relative dose intensity was 91.4%.

During chemotherapy, J-Q scores go elevated from day 1 to day 5 and gradually declined throughout the rest of the cycle. Without using frozen gloves, there was a significant increase according to courses (1st: 45.0 ± 5.7, 2nd: 76.7 ± 8.6, 3rd: 94.3 ± 11.8, 4th: 95.4 ± 11.8). Using frozen gloves, there was a significant increase from 1st course to 2nd, but no further increase was observed(1st: 37.4 ± 8.1, 2nd: 61.9 ± 12.4, 3rd: 62.9 ± 10.4, 4th: 55.3 ± 10.6). After six month and one year, the scores were significantly lower compared with the last day of the fourth cycle (4.28 ± 0.50, 2.53 ± 0.25, 2.85 ± 0.39, respectively). CTC, grade 2 or more sensory disturbance was observed in 57.9% after four cycles, but improved to 9.5% and 5.4% after six month and one year respectively.

CONCLUSIONS:

Patient-reported nPIPN was significantly getting worse without frozen gloves during chemotherapy, however be largely reversible within 1 year of PST or adjuvant treatment. The J-Q findings support that nab-PTX treatment is tolerable.

Citation Format: Yoshidome K, Morimoto T, Matsunami N, Tsunashima R, Tsukamoto F, Ryo T, Nishida Y, Shimo T, Anno K, Shimada M, Udo M, Kagawa M, Morishima H, Oda N. Nanoparticle albumin-bound paclitaxel-induced peripheral neuropathy in patients receiving neoadjuvant or adjuvant chemotherapy for breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-11-17.

Stimulation of liver regeneration after hepatectomy in mice by injection of bone marrow mesenchymal stem cells via the portal vein

AIM

To investigate whether mouse bone marrow mesenchymal stem cells (BMC) stimulate liver regeneration after partial hepatectomy.

METHODS

Isolated BMCs were purified by density gradient centrifugation. We performed a 70% hepatectomy in male BALB/c mice followed by injection of BMCs into the portal vein (PV-BMC group), or the tail vein (IV-BMC group), or of saline into the portal vein (control group).

RESULTS

The wet weight of the liver remnant increased significantly in the PV-BMC group at 3 and 5 days after hepatectomy compared with the IV-BMC and control groups. The Ki-67 labeling index revealed that the increase to result from stimulation of DNA synthesis. The constitutive interleukin-6 and hepatocyte growth factor mRNAs in the remnant liver tended to increase in the PV-BMC group at 3 days after hepatectomy.

CONCLUSIONS

These results demonstrated that BMC injection into the portal vein enhanced liver growth after partial hepatectomy in mice.

Dehydroxymethylepoxyquinomicin (DHMEQ) can suppress tumour necrosis factor-α production in lipopolysaccharide-injected mice, resulting in rescuing mice from death in vivo

Dehydroxymethylepoxyquinomicin (DHMEQ), a new nuclear factor (NF)-κB inhibitor, has several beneficial effects, including the suppression of tumour growth and anti-inflammatory effects. DHMEQ can also suppress the production of tumour necrosis factor (TNF)-α induced by lipopolysaccharide (LPS) in vitro. In the present study, we examine the effects of DHMEQ on TNF-α production in vivo and on the survival of mice injected with LPS. When DHMEQ was injected into mice 2 h before LPS injection, the survival of the LPS-injected mice was prolonged. When DHMEQ was injected twice (2 h before LPS injection and the day after LPS injection), all the mice were rescued. The injection of DHMEQ 1 h after LPS injection and the day after LPS injection also resulted in the rescue of all mice. The serum levels of TNF-α in the mice that received both LPS and DHMEQ were suppressed compared to the mice that received only LPS. These results suggest that DHMEQ can be utilized for the prevention and treatment of endotoxin shock.

Different hepatic vascular response to noradrenaline and histamine between guinea-pig and rat

AIM

Hepatic xenotransplantation from guinea-pig to rat has not been established. This failure is partly ascribed to differences in hepatic vascular characteristics between two species. However, the differences in hepatic vascular resistance distribution and responses to vasoconstrictors are not known. The present study was designed to determine basal levels of segmental vascular resistances and the responses to histamine and noradrenaline in isolated guinea-pig and rat livers.

METHODS

The livers were haemoperfused (Hct 8.3%) via the portal vein at a constant flow. The sinusoidal pressure was measured by the double occlusion pressure, and was used to determine the pre- (Rpre) and post-sinusoidal (Rpost) resistances.

RESULTS

There was no significant difference in basal total hepatic vascular resistance (Rt) between two species, whereas Rpre in rat (69% of Rt) was significantly greater than that in guinea-pig (61% of Rt). The responses to noradrenaline were similar; Rpre increased in a greater magnitude than Rpost, and liver weight was reduced. However, the noradrenaline-induced increase in Rt was greater in rats than in guinea-pigs. In contrast, histamine increased predominantly Rpost over Rpre, and increased liver weight in guinea-pig, while it affected no haemodynamic variables in rat.

CONCLUSION

There exist species differences in the hepatic vasculature between rat and guinea-pig. Basal pre-sinusoidal resistance in rat is greater than that in guinea-pig. Although noradrenaline predominantly contracts pre-sinusoidal vessels in both species, histamine causes predominant post-sinusoidal vasoconstriction in guinea-pig liver, while it has no vasoactive effects on rat liver.

Involvement of CTGF, a hypertrophic chondrocyte-specific gene product, in tumor angiogenesis

Connective tissue growth factor (CTGF) is a potent secreted signaling factor which functions in multiple stages of angiogenesis. In the present study, we examined the role of CTGF in tumor angiogenesis and made the following observations: (1) Histological analysis of human breast cancer (MDA231) cell and human fibrosarcoma (HT1080) cell xenografts in BALB/c nude mice showed a high level of neovascularization. Human squamous cell carcinoma (A431) xenografts induced only a low level of neovascularization. (2) CTGF mRNA was strongly expressed in MDA231 and in HT1080 cells in vivo and in vitro, but not in A431 cells. (3) CTGF protein was markedly produced in MDA231 cells and HT1080 cells and secreted into culture medium, and its production was greater during phases of growth rather than confluency. (4) Production of CTGF in bovine aorta endothelial cells was induced by CTGF, VEGF, bFGF and TGF-beta. (5) Neovascularization induced by HT1080 cells or MDA231 cells on chicken chorioallantoic membrane was suppressed in the presence of neutralizing CTGF-specific polyclonal antibody. These results suggest that CTGF regulates progression in tumor angiogenesis and the release or secretion of CTGF from tumor cells is essential for the angiogenesis.

Connective tissue growth factor as a major angiogenic agent that is induced by hypoxia in a human breast cancer cell line

Connective tissue growth factor (CTGF) is known to be a potent angiogenic factor. Here, we present the evidence that the hypoxic induction of angiogenesis by human breast cancer cells (MDA-231) can be ascribed at least in part to CTGF. Our results indicate that (i) CTGF is abundantly present in MDA-231 cells in vitro and in vivo, (ii) its secretion is up-regulated by hypoxia, and (iii) its gene expression is enhanced in MDA-231 cells cultured under hypoxic conditions. These data suggest CTGF may stimulate angiogenesis by paracrine mechanisms, thereby contributing to the invasion of breast cancer cells. This is the first evidence that human cancer cells differentially express CTGF protein and mRNA under the control of hypoxic conditions.

Development of stratum intermedium and its role as a Sonic hedgehog-signaling structure during odontogenesis

Stratum intermedium is a transient and subtle epithelial structure closely associated with inner dental epithelium in tooth germs. Little is known about its development and roles. To facilitate analysis, we used bovine tooth germs, predicting that they may contain a more conspicuous stratum intermedium. Indeed, early bell stage bovine tooth germs already displayed an obvious stratum intermedium with a typical multilayered organization and flanking the enamel knot. Strikingly, with further development, the cuspally located stratum intermedium underwent thinning and involution, whereas a multilayered stratum intermedium formed at successive sites along the cusp-to-cervix axis of odontogenesis. In situ hybridization and immunohistochemistry showed that stratum intermedium produces the signaling molecule Sonic hedgehog (Shh). Maximal Shh expression was invariably seen in its thickest multilayered portions. Shh was also produced by inner dental epithelium; expression was not constant but varied with development and cytodifferentiation of ameloblasts along the cusp-to-cervix axis. Interestingly, maximal Shh expression in inner dental epithelium did not coincide with that in stratum intermedium. Both stratum intermedium and inner dental epithelium expressed the Shh receptor Patched2 (Ptch2), an indication of autocrine signaling loops. Shh protein, but not RNA, was present in underlying dental mesenchyme, probably resulting from gradual diffusion from epithelial layers and reflecting paracrine loops of action. To analyze the regulation of Shh expression, epithelial and mesenchymal layers were separated and maintained in organ culture. Shh expression decreased over time, but was maintained in unoperated specimens. Our data show for the first time that stratum intermedium is a highly regulated and Shh-expressing structure. Given its dynamic and apparently interactive properties, stratum intermedium may help orchestrate progression of odontogenesis from cusp to cervix.

Novel mode of processing and secretion of connective tissue growth factor/ecogenin (CTGF/Hcs24) in chondrocytic HCS-2/8 cells

The synthesis, processing, and secretion of human connective tissue growth factor (CTGF/Hcs24) in a human chondrocytic cell line, HCS-2/8, were analyzed immunochemically. By metabolic pulse-labeling, chasing, and subsequent immunoprecipitation analyses, active synthesis of CTGF was observed not only in growing HCS-2/8 cells, but also in confluent cells. However, secretion and processing of CTGF were found to be regulated differentially, depending upon the growth status. During phases of growth, HCS-2/8 cells released CTGF molecules immediately without sequestering them within the cell layer. In contrast, after the cells reached confluence, the secretion slowed, resulting in an accumulation of CTGF in the cells or extracellular matrices (ECMs). Also, in confluent cell layers, a 10 kDa protein that was reactive to an anti-CTGF serum was observed. This CTGF-related small protein was not detected immediately after labeling, but gradually appeared within 6 h after chase, which suggests its entity as a processed subfragment of CTGF. Surprisingly, the 10 kDa protein was stable even 48 h after synthesis, and was not released by ECM digestion, suggesting an intracellular maintenance and function. Taken together, the behavior of CTGF in HCS-2/8 cells is remarkably different from that reported in fibroblasts, which may represent unique roles for CTGF in the growth and differentiation of chondrocytes.

Regulatory mechanism of human connective tissue growth factor (CTGF/Hcs24) gene expression in a human chondrocytic cell line, HCS-2/8

CTGF/Hcs24 is a multi-functional growth factor that potentiates either the growth or differentiation of mesenchymal cells, according to the biological conditions. Among various functional aspects of CTGF/Hcs24, it is especially notable that CTGF/Hcs24 may promote endochondral ossification in growth cartilage through all stages, and it is highly expressed in a human chondrosarcoma-derived chondrocytic cell line (HCS-2/8). In this study, to clarify the regulatory mechanism of CTGF/Hcs24 gene expression in chondrocytes, we analyzed the transcriptional activity of the CTGF/Hcs24 promoter and the effect of the CTGF/Hcs24 3'-untranslated region (3'-UTR) on gene expression in HCS-2/8 by means of an established DNA transfection and luciferase reporter gene assay system. As a result, the luciferase activity of the CTGF/Hcs24 promoter was found to be remarkably high in HCS-2/8. The 3'-UTR of the CTGF/Hcs24 gene strongly repressed the luciferase activity in HCS-2/8, when it was linked to the downstream of the luciferase reporter gene, suggesting its functionality also in chondrocytic cells. Deletion analysis of the CTGF/Hcs24 promoter clarified a major segment responsible for the enhanced CTGF/Hcs24 promoter activity in HCS-2/8. The TGF-beta response element in the DNA segment was active in HCS-2/8, and point mutations in the element moderately decreased the highly maintained promoter activity with total loss of TGF-beta responsiveness. These results indicate that the strong expression of the CTGF/Hcs24 gene in HCS-2/8 was mainly caused by high transcriptional activity of the CTGF/Hcs24 promoter, and that the TGF-beta response element is one of the critical elements that support the high transcription activity.

Modifying effects of ethinylestradiol but not methoxychlor on N-ethyl-N-nitrosourea-induced uterine carcinogenesis in heterozygous p53-deficient CBA mice

It is unknown whether endocrine-disrupting chemicals (EDCs) with estrogenic activities have any modifying effects on uterine carcinogenesis. In our previous study, we established a uterine-carcinogenesis model that is useful for detecting tumor-modifying effects of EDCs by the administration of N-ethyl-N-nitrosourea (ENU) to female heterozygous p53-deficient CBA mice [p53 (+/-) mice]. To investigate the effects of ethinylestradiol (EE) and methoxychlor (MXC) on development of ENU-induced uterine tumors, female p53 (+/-) mice and their wild-type littermates [p53 (+/+) mice] received an intraperitoneal injection of 120 mg/kg body weight (bw) of ENU, followed, in Group 1, by no further treatment; in Group 2, by a diet containing 1 ppm EE; in Group 3, by a diet containing 5 ppm EE for 4 weeks and 2.5 ppm EE thereafter; and in Group 4, by a diet containing 2000 ppm MXC for 26 weeks. Uterine proliferative lesions that were induced were composed of both endometrial-stromal and epithelial-cell types. Endometrial stromal sarcomas were induced in p53 (+/-) mice of Groups 1 to 4, and the incidence (87%) in Group 3 was significantly increased compared to Group 1 (47%). Atypical hyperplasias (clear-cell type) of the endometrial gland in p53 (+/-) mice were seen at incidences of 0, 14, 60, and 0% in Groups 1, 2, 3, and 4, respectively, while their incidence in p53 (+/+) mice was 0, 7, 53, and 0%, respectively, with a significant difference between Groups 1 and 3 in both cases. One p53 (+/-) mouse in Group 3 also had an adenocarcinoma consisting of clear cells, and the PCNA labeling indices of the clear-cell atypical hyperplasias, and this endometrial adenocarcinoma, were higher than those of glandular hyperplasias. The present study suggests that 2.5 ppm EE, but not MXC, exerts tumor-promoting effects on stromal and epithelial proliferative lesions of the uteri in p53 (+/-) mice initiated with ENU.

Studies on the carcinogenicity of potassium iodide in F344 rats

A chronic toxicity and carcinogenicity study, in which male and female F344/DuCrj rats were given potassium iodide (KI) in the drinking water at concentrations of 0, 10, 100 or 1000 ppm for 104 weeks, and a two-stage carcinogenicity study of application at 0 or 1000 ppm for 83 weeks following a single injection of N-bis(2-hydroxypropyl)nitrosamine (DHPN), were conducted. In the former, squamous cell carcinomas were induced in the salivary glands of the 1000 ppm group, but no tumors were observed in the thyroid. In the two-stage carcinogenicity study, thyroidal weights and the incidence of thyroid tumors derived from the follicular epithelium were significantly increased in the DHPN+KI as compared with the DHPN alone group. The results of our studies suggest that excess KI has a thyroid tumor-promoting effect, but KI per se does not induce thyroid tumors in rats. In the salivary gland, KI was suggested to have carcinogenic potential via an epigenetic mechanism, only active at a high dose.

Effects of CTGF/Hcs24, a hypertrophic chondrocyte-specific gene product, on the proliferation and differentiation of osteoblastic cells in vitro

Connective tissue growth factor/hypertrophic chondrocyte-specific gene product Hcs24 (CTGF/Hcs24) promotes the proliferation and differentiation of chondrocytes and endothelial cells which are involved in endochondral ossification (Shimo et al., 1998, J Biochem 124:130-140; Shimo et al., 1999, J Biochem 126:137-145; Nakanishi et al., 2000, Endocrinology 141:264-273). To further clarify the role of CTGF/Hcs24 in endochondral ossification, here we investigated the effects of CTGF/Hcs24 on the proliferation and differentiation of osteoblastic cell lines in vitro. A binding study using (125)I-labeled recombinant CTGF/Hcs24 (rCTGF/Hcs24) disclosed two classes of specific binding sites on a human osteosarcoma cell line, Saos-2. The apparent dissociation constant (Kd) value of each binding site was 17.2 and 391 nM, respectively. A cross-linking study revealed the formation of (125)I-rCTGF/Hcs24-receptor complex with an apparent molecular weight of 280 kDa. The intensity of (125)I-rCTGF/Hcs24-receptor complex decreased on the addition of increasing concentrations of unlabeled rCTGF/Hcs24, but not platelet-derived growth factor-BB homodimer or basic fibroblast growth factor. These findings suggest that osteoblastic cells have specific receptor molecules for CTGF/Hcs24. rCTGF/Hcs24 promoted the proliferation of Saos-2 cells and a mouse osteoblast cell line MC3T3-E1 in a dose- and time-dependent manner. rCTGF/Hcs24 also increased mRNA expression of type I collagen, alkaline phosphatase, osteopontin, and osteocalcin in both Saos-2 cells and MC3T3-E1 cells. Moreover, rCTGF/Hcs24 increased alkaline phosphatase activity in both cells. It also stimulated collagen synthesis in MC3T3-E1 cells. Furthermore, rCTGF/Hcs24 stimulated the matrix mineralization on MC3T3-E1 cells and its stimulatory effect was comparable to that of bone morphogenetic protein-2. These findings indicate that CTGF/Hcs24 is a novel, potent stimulator for the proliferation and differentiation of osteoblasts in addition to chondrocytes and endothelial cells. Because of these functions, we are re-defining CTGF/Hcs24 as a major factor to promote endochondral ossification to be called "ecogenin: endochondral ossification genetic factor."

Novel intracellular effects of human connective tissue growth factor expressed in Cos-7 cells

To clarify the multiple functionality of connective tissue growth factor (CTGF), we examined the effects of nascent CTGF within the cell by transient expression. In Cos-7 cells, expression of human CTGF induced an altered cell morphology. It was associated with an increased cellular DNA content and loose attachment, indicating the cells were in G2/M phase. Overexpression of CTGF did not induce cell growth, whereas recombinant CTGF efficiently stimulated the proliferation extracellularly. These results indicate that intracellular CTGF may act as an antimitotic agent, thus it should also be noted that nascent CTGF was found to accumulate around the central mitotic machinery.

Rapid induction of uterine tumors with p53 point mutations in heterozygous p53-deficient CBA mice given a single intraperitoneal administration of N-ethyl-N-nitrosourea

To investigate the sensitivity of heterozygous p53-deficient CBA mice to carcinogens, 20 female mice [p53(+/-)] and 20 wild-type littermates [p53(+/+)] were given an intraperitoneal injection of 120 mg/kg body wt of N-ethyl-N-nitrosourea (ENU) and were maintained without any other treatment for a further 26 weeks. Histopathology showed that uterine tumors (endometrial polyps and stromal sarcomas) and lung adenomas were induced in both p53(+/-) and p53(+/+) mice. The incidence of uterine tumors and lung adenomas (94% and 81%, respectively) in p53(+/-) mice was significantly greater than that in p53 (+/+) mice (37% and 42%, respectively). Malignant lymphomas were only induced in p53(+/-) mice, at an incidence of 31%. Concerning uterine tumors and preneoplastic lesions, there were endometrial stromal sarcomas and atypical hyperplasias of the endometrial gland in 90% and 63%, respectively, of p53(+/-) mice, with significantly greater incidences than in p53(+/+) mice. Gene analysis revealed GCG-->GTG point mutations in codon 135 of exon 5 of the p53 allele in all of the uterine endometrial stromal sarcomas examined. Our results suggest that female p53(+/-) CBA mice are very susceptible to uterine carcinogenesis, providing a useful model for ENU-induced uterine tumors.

Effects of CTGF/Hcs24, a product of a hypertrophic chondrocyte-specific gene, on the proliferation and differentiation of chondrocytes in culture

Recently, we cloned a messenger RNA (mRNA) predominantly expressed in chondrocytes from a human chondrosarcoma-derived chondrocytic cell line, HCS-2/8, by differential display PCR and found that its gene, named hcs24, was identical with that of connective tissue growth factor (CTGF). Here we investigated CTGF/Hcs24 function in the chondrocytic cell line HCS-2/8 and rabbit growth cartilage (RGC) cells. HCS-2/8 cells transfected with recombinant adenoviruses that generate CTGF/Hcs24 sense RNA (mRNA) proliferated more rapidly than HCS-2/8 cells transfected with control adenoviruses. HCS-2/8 cells transfected with recombinant adenoviruses that generate CTGF/Hcs24 sense RNA expressed more mRNA of aggrecan and type X collagen than the control cells. To elucidate the direct action of CTGF/Hcs24 on the cells, we transfected HeLa cells with CTGF/Hcs24 expression vectors, obtained stable transfectants, and purified recombinant CTGF/Hcs24 protein from conditioned medium of the transfectants. The recombinant CTGF/Hcs24 effectively promoted the proliferation of HCS-2/8 cells and RGC cells in a dose-dependent manner and also dose dependently increased proteoglycan synthesis in these cells. In addition, these stimulatory effects of CTGF/Hcs24 were neutralized by the addition of anti-CTGF antibodies. Furthermore, the recombinant CTGF/Hcs24 effectively increased alkaline phosphatase activity in RGC cells in culture. Moreover, RT-PCR analysis revealed that the recombinant CTGF/Hcs24 stimulated gene expression of aggrecan and collagen types II and X in RGC cells in culture. These results indicate that CTGF/Hcs24 directly promotes the proliferation and differentiation of chondrocytes.

Connective tissue growth factor induces the proliferation, migration, and tube formation of vascular endothelial cells in vitro, and angiogenesis in vivo

Connective tissue growth factor (CTGF) is a novel cysteine-rich, secreted protein. Recently, we found that inhibition of the endogenous expression of CTGF by its antisense oligonucleotide and antisense RNA suppresses the proliferation and migration of vascular endothelial cells. In the present study, the following observations demonstrated the angiogenic function of CTGF in vitro and in vivo: (i) purified recombinant CTGF (rCTGF) promoted the adhesion, proliferation and migration of vascular endothelial cells in a dose-dependent manner under serum-free conditions, and these effects were inhibited by anti-CTGF antibodies; (ii) rCTGF markedly induced the tube formation of vascular endothelial cells, and this effect was stronger than that of basic fibroblast growth factor or vascular endothelial growth factor; (iii) application of rCTGF to the chicken chorioallantoic membrane resulted in a gross angiogenic response, and this effect was also inhibited by anti-CTGF antibodies. (iv) rCTGF injected with collagen gel into the backs of mice induced strong angiogenesis in vivo. These findings indicate that CTGF is a novel, potent angiogenesis factor which functions in multi-stages in this process.

Pulmonary fibrosis caused by N-methyl-N-nitrosourethane inhibits lung tumorigenesis by urethane in transgenic mice carrying the human prototype c-Ha-ras gene

Male and female transgenic mice carrying the human prototype c-Ha-ras gene (rasH2 mice) and their wild littermates (non-Tg mice) received three subcutaneous injections of 0.3 mg N-methyl-N-nitrosourethane (MNUR) once every 2 weeks for the first 4 weeks followed by a single intraperitoneal injection of 1000 or 0 mg/kg urethane (UR) 2 weeks later. They were then maintained without any other treatment for a further 13 weeks and sacrificed for assessment of pulmonary pathology. Inflammatory lesions, such as macrophage infiltration, alveolar bronchiolization and/or fibrosis, were induced in both rasH2 and non-Tg mice treated with MNUR or MNUR + UR. Lung proliferative lesions were induced in 100% of the UR-treated rasH2 mice but to a significantly lesser extent in the MNUR + UR case. The incidences of lung tumors in non-Tg mice treated with UR or MNUR + UR were relatively low. Point mutations of the transgene were detected in approximately 80% of lung tumors in rasH2 mice treated with UR and MNUR + UR, but murine Ki-ras mutations were rare. No marked difference in the mutation pattern was found between the UR-treated and the MNUR + UR-treated rasH2 mice. In non-Tg mice treated with UR or MNUR + UR, point mutations of the murine c-Ki-ras gene were observed in about 50% of the lung tumors examined. The present study confirmed that rasH2 mice are very sensitive to lung tumor induction by UR and suggested that alveolar epithelial cells in the reparative stage during pulmonary fibrosis are resistant to DNA damage by this carcinogen.

Inhibition of endogenous expression of connective tissue growth factor by its antisense oligonucleotide and antisense RNA suppresses proliferation and migration of vascular endothelial cells

Previously, we cloned an mRNA predominantly expressed in hypertrophic chondrocytes by differential display-PCR from a human chondrosarcoma-derived chondrocytic cell line (HCS-2/8) that is identical to that of connective tissue growth factor (CTGF). In the present study, we investigated the roles of CTGF in the proliferation and migration of vascular endothelial cells using its antisense oligonucleotide and antisense RNA, because angiogenesis into the hypertrophic zone of cartilage occurs at the final step of endochondral ossification. Immunohistochemical and immunofluorescence techniques revealed that not only hypertrophic chondrocytes but also endothelial cells in the cost-chondral junctions of mouse ribs were stained with an anti-CTGF antibody in vivo. Northern blot analysis revealed that CTGF was strongly expressed in chondrocytic cells as well as bovine aorta endothelial (BAE) cells in culture, but not in other types of cells such as osteoblastic cells. Its expression in BAE cells was greater in the growing phase than in the confluent phase. When one-half of a monolayer of a confluent culture of BAE cells had been peeled off, only the cells proliferating and extending into the vacant area were stained with the anti-CTGF antibody. The addition of an antisense oligonucleotide inhibited the proliferation and extension of the BAE cells into the vacant area. The antisense oligonucleotide also inhibited the proliferation of BAE cells in the rapidly proliferating phase. In a Boyden chamber assay, pretreatment with the antisense oligonucleotide markedly inhibited the migration of BAE cells. Furthermore, the abilities to proliferate and migrate of BAE cells, which were stably transfected with expression vectors that generate the antisense RNA of CTGF cDNA, were markedly lower than those of the control. These findings suggest that endogenous CTGF expression is involved in the proliferation and migration of BAE cells.

Demonstration of receptors specific for connective tissue growth factor on a human chondrocytic cell line (HCS-2/8)

The presence of receptors specific for connective tissue growth factor (CTGF) was demonstrated on a human chondrosarcoma-derived chondrocytic cell line, HCS-2/8. The binding of 125I-labeled recombinant CTGF to HCS-2/8 cells was inhibited by unlabeled CTGF but not by PDGF-BB or bFGF. Scatchard analysis revealed the presence of two classes of binding sites with Kd values of 18.6 and 259 nM on cells. A cross-linking study revealed the formation of 125I-CTGF-receptor complex with an apparent molecular weight of 280 kDa. The 125I-CTGF-receptor complex disappeared almost completely on the addition of unlabeled CTGF but not PDGF-BB or bFGF. In addition, the 125I-CTGF-receptor complex was immunoprecipitated with anti-CTGF antiserum but not with anti-PDGF receptor antiserum. These findings suggest that CTGF directly binds to specific receptor molecules on HCS-2/8 cells.

Induction of squamous cell carcinomas in the salivary glands of rats by potassium iodide

In a 2-year carcinogenicity study of potassium iodide (KI) in F344/DuCrj rats, squamous cell carcinomas (SCCs) were observed in the salivary glands of 4/40 males and 3/40 females receiving 1000 ppm KI in the drinking water. Ductular proliferation with lobular atrophy was observed at high incidence in the submandibular glands of the high-dose animals, and squamous metaplasia was frequently evident within the proliferative ductules and the larger interlobular ducts. A transition from metaplasia to SCC was apparent. The results suggest that squamous metaplasia in proliferative ductules, occurring secondarily to lobular impairment induced by KI, may develop into SCCs via a non-genotoxic, proliferation-dependent mechanism.

Mice with focal pulmonary fibrosis caused by monocrotaline are insensitive to urethane induction of lung tumorigenesis

To establish the characteristics of an optimized pulmonary fibrosis model, male ICR mice were given 4 weekly sc injections of 150 or 0 mg/kg monocrotaline (MCT) and maintained without further treatment for 33 wk (Experiment 1). The final mortality in the MCT group was 64%. Epithelial cells with large bizarre nuclei and an increased incidence of alveolar/bronchiolar hyperplasias were typically observed. In areas of pulmonary fibrosis, the PCNA labeling index (LI) in the alveolar/airway epithelium was significantly elevated. DNA content analysis demonstrated a larger range (4-8C) for the ploidy pattern of alveolar epithelium with large bizarre nuclei than in the normal epithelium (2C). In Experiment 2, the relationship between pulmonary fibrosis development and lung tumorigenesis was investigated. Mice were given 4 weekly sc injections of 150 and 0 mg/kg MCT, followed by a single i.p. injection of 1,000 or 500 mg/kg urethane (UR) on week 7, then maintained without further treatment for an additional 15 wk. UR following MCT-induced inflammatory changes, fibrosis, and epithelia with large bizarre nuclei but no tumorous lesions, in spite of the fact that treatment with UR alone caused a high incidence of pulmonary tumors. Hyperplasias were seen in all groups, but the multiplicity in the combined groups tended to be decreased by the MCT pretreatment. The present study demonstrated that this new protocol is more suitable than previous one for the experimental production of pulmonary fibrosis. Furthermore, the induction of lung tumors by UR was completely depressed in mice with MCT-induced pulmonary fibrosis, suggesting that alveolar epithelial cells are resistant to this lung carcinogen under these conditions.

Lack of carcinogenicity of cyanoguanidine in F344 rats

The carcinogenicity of cyanoguanidine, a compound used in the production of melamine, guanidine salts and guanamine derivatives, was examined in male and female Fischer 344 rats fed CRF-1 pulverized diets containing 0, 2.5 and 5% cyanoguanidine for up to 2 yr. The rats were randomly allocated to three groups, each consisting of 50 males and 50 females. The mean body weight gains in both sexes of the 5% group and in females of the 2.5% group were significantly lower than the control values after wk 1 of treatment. No other signs of toxicity were seen in any of the rats throughout the treatment period. Histopathologically, various tumours developed in all groups, including the control group, but these were all similar to those known to occur spontaneously in this strain of rats, and no toxicologically significant increase was found for any lesion type in the treated groups. On the basis of these results, it is concluded that cyanoguanidine exerts no carcinogenic potential in F344 rats when administered for up to 2 yr under the conditions of the present study.

Comparison of ultrastructural changes in thyrotrophs of the rat pituitary between intermittent and continuous treatments with sulfadimethoxine

To clarify relationships between serum thyroid-stimulating hormone (TSH) levels and ultrastructural changes in thyrotrophs caused by intermittent or continuous treatments with antithyroid compound, male Fischer-344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN) were given water containing 0.1% sulfadimethoxine (SM) for 8 wk and then sacrificed (Group 1). Additional groups were examined 2 wk after withdrawal (Group 2), after 4 wk retreatment following a 2-wk withdrawal period (Group 3), and after 14 wk continuous exposure (Group 4). Control rats (Group 5) remained untreated for 8 wk after the DHPN initiation. Microscopic examination revealed hypertrophy of thyrotrophs and depletion of TSH-positive material in Groups 1, 3, and 4 but a return to normal in Group 2. Electron microscopic examination of thyrotrophs in the anterior pituitary in Groups 1, 3, and 4 revealed dilated rough endoplasmic reticulum (ER) cisternae with intracisternal dense granules as well as diminished numbers of intracytoplasmic secretory granules, these changes being most marked in Group 1 and least pronounced in Group 4. The number of intracytoplasmic secretory granules in Group 3 was much lower than in Group 4, as demonstrated by morphometric analysis. In Group 2, thyrotrophs showed dilated rough ER cisternae without intracisternal dense granules and essentially the same component of intracytoplasmic secretory granules as Group 5. The present study suggest that while prolonged continuous treatment with SM results in gradual acclimation to an increased demand for TSH, intermittent treatment elicits a persistent state of reduced TSH storage in thyrotrophs due to a continued strong feedback through the hypothalamus-pituitary-thyroid axis.

Morphometric and immunohistochemical studies on atrophic changes in lympho-hematopoietic organs of rats treated with piperonyl butoxide or subjected to dietary restriction

Changes observed in lympho-hematopoietic organs in rats given piperonyl butoxide may be attributable either to direct toxic effects or to undernutrition. Male F344 rats were therefore fed diet containing 2.5% piperonyl butoxide or subjected to a 64% restriction of food intake for 2 weeks. Marked inhibition of body weight gain, decreased white blood cell count, depletion of T/B lymphocytes in lymphoid tissues, hypoplasia of the bone marrow, and decreased proliferating cell nuclear antigen (PCNA) labeling indices in these tissues were seen in both dietary restriction and 2.5% piperonyl butoxide groups. The depletion of T lymphocytes in the thymus and spleen was stronger in the 2.5% piperonyl butoxide group, as indicated by PCNA labeling indices and image analysis of T lymphocyte areas of the spleen, however, the toxicological profile observed for the chemically treated group was essentially the same as for animals on the restricted diet. These results suggest that the lympho-hematopoietic findings in rats receiving 2.5% piperonyl butoxide are probably due to undernutrition resulting from a reduced food intake.

Promoting effect of large amounts of vitamin A on cell proliferation of thyroid proliferative lesions induced by simultaneous treatment with thiourea

In order to examine modifying effects of simultaneous treatment with large amounts of vitamin A (VA) and thiourea (TU) on the thyroid tumorigenesis in rats, male F344 rats were initiated with N-bis(2-hydroxypropyl)nitrosamine (2800 mg/kg body weight, single s.c. injection), and starting 1 week later received diet containing 0.1% VA (VA group), drinking water containing 0.2% TU (TU group), 0.2% TU + 0.1% VA (TU + VA group) or tap water/basal diet (control group) for 19 weeks. Serum T3 and T4 in the TU and TU + VA groups were significantly decreased as compared to the control group, while serum TSH levels were remarkably increased. The ratios of T3 and T4 decrease and TSH increase in the TU + VA group were remarkably more pronounced than in the TU group. Thyroid neoplastic lesions were only induced in the TU and TU + VA groups. The multiplicity of intracapsular follicular cell proliferative foci in the TU + VA group was significantly increased as compared to the TU group value. Cell proliferation of hypertrophic and subcapsular follicular cells, as well as in hyperplasias, and neoplasias with adenomatous growth pattern was significantly higher in the combined treatment case than after TU alone. In the liver, centrilobular hypertrophy of hepatocytes was seen in the TU and TU + VA groups, this being especially marked in the latter group. In the combined group case the affected cells were strongly positive for GST-P antibody binding. The results of the present study suggest that cell proliferation of thyroid follicular cell proliferative lesions in rats is enhanced by strong TSH stimulation with simultaneous treatment of TU and large amounts of VA.

[Modifying effects of goitrogens on the tumor development in the liver and lung of rats]

In order to investigate whether goitrogens and liver enzyme-inducers modify the tumorigenesis in the liver or lung, 6-week old male F344 rats were given single subcutaneous injection of DHPN, and starting one week later received water containing goitrogens, namely sulfadimethoxine (SDM), propylthiouracil (PTU) and potassium thiocyanate (KSCN), or an enzyme-inducer, phenobarbital (PB), for 19 weeks ad libitum. Although the number of GST-P positive foci in the liver was significantly increased in the PB group as compared to the control group, there were no significant fluctuations in the SDM, PTU and PB groups. With respect to the lung, it is suggested that SDM, KSCN and PB may enhance the lung tumorigenesis, since the multiplicities of hyperplasias of alveolar epithelia were increased in groups treated with these compounds.

Effect of rat thyroid proliferative lesion development by intermittent treatment with sulfadimethoxine

To determine whether production of thyroid proliferative lesions would be enhanced by intermittent rather than continuous treatment with a goitrogen, male F344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN, 2800 mg/kg body weight, single s.c. injection) were given water containing 0.1% sulfadimethoxine (SM) for 20 weeks (group 1) or 0.1% SM for the first 8 weeks followed by 2 cycles consisting of 2 weeks withdrawal and 4 weeks retreatment with 0.1% SM (group 2). Control rats (group 3) were untreated for 20 weeks after the DHPN initiation. Serum T3 and T4 levels were significantly decreased in groups 1 and 2 compared to group 3. Serum thyroid stimulating hormone level was significantly increased in all treated groups compared to group 3. The numbers of follicular cell hyperplasias were significantly increased in group 2 compared to group 1. BrdU labeling indices for follicular cells and hyperplasias were also significantly elevated in group 2 compared to group 1. Electron microscopic examination of thyrotrophs in the anterior pituitary in groups 1 and 2 revealed dilated rough ER cisternae with intracisternal dense granules. The number of intracytoplasmic secretory granules in group 2 was moderately decreased compared to group 1. Therefore, the results of the present study suggest that it may be possible to enhance production of thyroid neoplastic lesions by intermittent treatment.

Morphological evaluation of cyclophosphamide testicular toxicity in rats using quantitative morphometry of spermatogenic cycle stages

The testicular toxicity of cyclophosphamide (Cp) in rats was evaluated by quantitative morphometry of spermatogenic cycle stages. Nine-week-old male Sprague-Dawley rats in Group 1 were given a single oral administration of 100 mg/kg of Cp, and were sacrificed at 1, 7, 14 and 21 days thereafter. Rats in Group 2 were orally given 100 mg/kg/day of Cp for 2 days, followed by 50 mg/kg/day for the next 3 days, and were sacrificed at 1 and 4 days after the last administration. The numbers of seminiferous epithelia were counted in the seminiferous tubules of stages II, V, VII and XII of the spermatogenic cycle. The data were expressed as numbers of spermatogenic cells per Sertoli cells per seminiferous tubule cross section. Animals in Group 1 showed decreased preleptotene spermatocytes at Day 7, decreased zygotene spermatocytes at Day 14, and decreased pachytene spermatocytes at Day 21. In group 2, testicular toxicity could also be clearly detected by this morphometric approach. The present morphometric study thus indicates that testicular toxicity can be detected from Day 7 even after a single administration of Cp.

Effect of thyroid stimulating hormone on the development and progression of rat thyroid follicular cell tumors

Time course changes in cell proliferative activity of thyroid focal hyperplastic and tumorous lesions as well as blood thyroid-related hormones in male F344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN: 2800 mg/kg body weight, single s.c. injection) were examined following chronic administration of 0.1% sulfadimethoxine (SM) in the drinking water for 1, 4, 8, 12 and 16 weeks and at the end of a subsequent 4-week recovery period. Serum thyroid stimulating hormone (TSH) levels increased rapidly from week 1 of SM treatment, reaching a peak at week 8, and then decreased gradually with prolongation of treatment period, although remaining significantly elevated as compared with the corresponding controls at all time points up to week 16. Follicular cell hyperplasias and adenomas of the thyroid occurred from week 4 and carcinomas from week 8. All of these lesions showed high cell proliferative activities corresponding to high serum TSH levels during the early stage, but the levels in hyperplasias and adenomas decreased rapidly with prolongation of SM treatment. After the recovery period, serum TSH levels had returned to below the normal range and cell proliferation in follicular hyperplasias and adenomas had stopped or was very low. Some carcinomas demonstrating invasive growth also showed remarkable decreases in the cell proliferative activity. The results of our study strongly suggest that a high serum TSH level plays an important role in the early stage of thyroid tumorigenesis and that some tumors exhibiting invasive growth are still dependent on TSH stimulation.

Study on the carcinogenicity of tannic acid in F344 rats

The carcinogenicity of tannic acid, a compound that is used as a food additive, a clarifying agent and a refining agent, was examined in F344 rats of both sexes. Tannic acid was dissolved in distilled water at concentrations of 0.25 and 0.5%. The doses were selected on the basis of results from a 13-wk subchronic study. Groups of 50 male and 50 female rats were given one of these solutions ad lib. as their drinking water for up to 2 yr. The mean body weights of the treated males were essentially comparable with those of the controls, whereas treated females had lower mean body weights than the control group. A variety of tumours developed in all groups, including the control group, but all the neoplasms were histologically similar to those known to occur spontaneously in this strain of rats, and no statistically significant increase in the incidence of any tumour was found in the treated groups of either sex. Thus, it is concluded that, under the conditions of the experiment, tannic acid has neither carcinogenic potential in F344 rats nor modifying effects on spontaneous tumour development.