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Biomedical subjects

S Koshika

Publications and source records attributed to S Koshika.

At least 19 recordsLinked to original sources
PubMed2001

Induction of SPARC by VEGF in human vascular endothelial cells.

SPARC/osteonectin/BM-40 is a matricellular protein that is thought to be involved in angiogenesis and endothelial barrier function. Previously, we have detected high levels of SPARC expression in endothelial cells (ECs) adjacent to carcinomas of kidney and tongue. Although SPARC-derived peptide showed an angiogenic effect, intact SPARC itself inhibited the mitogenic activity of vascular endothelial growth factor (VEGF) for ECs by the inhibiting phosphorylation of flt-1 (VEGF receptor 1) and subsequent ERK activation. Thus, the role of SPARC in tumor angiogenesis, stimulation or inhibition, is still unclear. To clarify the role of SPARC in tumor growth and progression, we determined the effect of VEGF on the expression of SPARC in human microvascular EC line, HMEC-1, and human umbilical vein ECs. VEGF increased the levels of SPARC protein and steady-state levels of SPARC mRNA in serum-starved HMEC-1 cells. Inhibitors (SB202190 and SB203580) of p38, a mitogen-activated protein (MAP) kinase, attenuated VEGF-stimulated SPARC production in ECs. Since intact SPARC inhibits phosphorylation ERK MAP kinase in VEGF signaling, it was suggested that SPARC plays a dual role in the VEGF functions, tumor angiogenesis, and extravasation of tumors mediated by the increased permeability of endothelial barrier function.

Cells, Cultured↗
PubMed2001

Cytostatic effect of inostamycin, an inhibitor of cytidine 5'-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG): inositol transferase, on oral squamous cell carcinoma cell lines.

Inostamycin, which was recently isolated from Streptomyces sp. MH816-AF15 as an inhibitor of cytidine 5'-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG): inositol transferase, caused a G1-phase accumulation in the cell cycle of small cell lung carcinomas. To investigate whether the cytostatic effect of inostamycin is restricted to lung carcinoma cell lines or applicable to other type of cells, we tested five oral squamous cell carcinoma (SCC) cell lines. Cell growth was suppressed in 62.5--125 ng/ml inostamycin in the culture medium in all oral cancer cell lines tested, with non-viable cells being <1%, indicating inostamycin is cytostatic on SCC cell lines. Decrease in cyclin D1 mRNA and protein expression due to the inostamycin treatment was accompanied by suppression of phosphorylated retinoblastoma susceptibility gene product (pRB-P) levels. Moreover, flow cytometric analysis showed that inostamycin induced an increase in G1/G0 cells (1.2--3.2 fold) over 24 h. These results suggest that inostamycin is a useful agent for tumour dormant cytostatic therapy for oral SCC.

Antineoplastic Agents↗
PubMed2001

Reduced expression of p16 and p27 proteins in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a malignant tumor with a high incidence in east Asian countries. Inactivation of cyclin-dependent kinase (CDK) inhibitors (CKIs) and overexpression of G1 cyclin has been thought to be important for tumor development. To determine whether reduction of CKI (p16 and p27) expression was associated with NPC development, we performed immunohistochemical staining of NPC specimens from 20 patients. We found that p16 and p27 proteins were negative in 8 of 20 and 16 of 20 cases, respectively; that either p16 or p27 proteins were negative in 17 of 20; and that both p16 and p27 were negative in 7 of 20. Excepting the cases in which both CKIs were negative, negativity of p27 alone was statistically higher than that of p16 (9/20 versus 1/20, P = .022), suggesting that the reduction of p27 protein is an important event for the multi-step process of NPC development.

Carcinoma, Squamous Cell↗
PubMed2000

High production of SPARC/osteonectin/BM-40 in mouse metastatic B16 melanoma cell lines.

Production of SPARC/osteonectin/BM-40 was determined in mouse B16 melanoma clones BL6 and F10 (high metastatic) and F1 (low metastatic). SPARC was produced greater amount in BL6 and F10 than in F1 cells, showing a good agreement with their metastatic potentials. Moreover, SPARC production was not influenced by culture pH, even in the acidic conditions (= pH 5.9). Although tumor tissues show often low pH due to excessive amount of acidic metabolites such as lactate, most studies have been done in neutral pH. High SPARC production in the acidic medium, therefore, is thought to be an important potential for tumor invasive behaviour.

Animals↗
PubMed2000

Inostamycin, an inhibitor of cytidine 5'-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG): inositol transferase, suppresses invasion ability by reducing productions of matrix metalloproteinase-2 and -9 and cell motility in HSC-4 tongue carcinoma cell line.

Inostamycin is an inhibitor of cytidine 5'-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG): inositol transferase. It significantly reduced epidermal growth factor (EGF)-induced in vitro invasion of the tongue carcinoma cell line, HSC-4, through reconstituted basement membrane Matrigel. Since phosphatidylinositol (PI) 4,5-biphosphate is important for signal transduction through protein kinase C and actin reorganisation, we further examined the effect of inostamycin on production of two matrix metalloproteinases (MMPs), MMP-2 and -9, and on cell motility. Zymographic analysis showed that inostamycin suppressed pro-MMP-2 and pro-MMP-9 levels at a dose-dependent fashion, while MMP-2 activity was not significantly affected. By reverse transcription-polymerase chain reaction, it was found that inostamycin diminished steady state levels of MMP-2 and -9 but not membrane type 1-MMP mRNA expressions. Inostamycin partially blocked both EGF- and phorbol 12-myristate 13-acetate-stimulated pro-MMP-9 production. A cytoplasmic calcium chelator (BAPTA-AM) dramatically elevated pro- MMP-9 and slightly elevated pro-MMP-2 secretions. EGF-stimulated motility of HSC-4 cells was suppressed by inostamycin treatment along with reduction of actin cytoskeletal reorganisation, filopodia formation and cdc42 expression. These results suggested that inostamycin would be useful for an anti-invasive agent in tongue cancer.

Base Sequence↗
PubMed1998

Inhibitory effects by a submandibular gland extract on luteinizing hormone-stimulated testosterone production by testicular cells.

In order to evaluate the role of the submandibular gland (SMG) on testosterone (T) production by the testis, primary cultured testicular cells were prepared from rats that had the submandibular gland surgically ablated (G-) and control (sham operated) rats (S.O.) respectively. The cells were incubated with or without 100 ng/ml luteinizing hormone (LH) and/or SMG extract. The same linear increase in T secretion was shown by both S.O. and G- cells on multi-stimulation with LH for up to 96 hrs. However, while an equivalent response was shown for S.O. cells after a single LH stimulation at 96 hrs, T secretion by the G- cells reached a plateau after 24 hrs. The level at 96 hrs was thus approximate 30% and 33% of those of S.O. cells with and without multi-stimulus by LH for 96 hrs, respectively. When S.O. cells were cultured with SMG extract, LH-stimulated T secretion was dose-dependently inhibited and there was no effect on basal T secretion. The inhibitory effect was abolished by treatment at 95 degrees C for 5 min. Ultra-filtration indicated that the molecular size of the inhibitory agent was greater than 30,000. It is proposed that SMG may contain a high molecular weight, heat labile soluble factor(s) which affects T secretion by inhibiting LH action in testicular cells.

Animals↗
PubMed1996

Testosterone metabolism in new squamous cell carcinoma cell line (RSS18) from 7,12-dimethylbenz[a]anthracene-induced submandibular gland of female rat.

We established a new squamous cell carcinoma cell line, designated RSS18, from a 7,12-dimethyl-benz[a]anthracene (DMBA)-induced submandibular gland of the female rat, and investigated a testosterone metabolism in the cells. During 6 h incubation of RSS18 cells with testosterone as a substrate, the cells produced a significant amount of 5alpha-dihydrotestosterone (DHT) and three kinds of minor metabolites, and their percentages metabolized against total metabolites were in descending order of DHT (89 %) > 5alpha-androstane-3alpha,17beta-diol (9.0 %) > 5alpha-androstanedione(1.6%) > 4-androstene-3,17-dione (0.69%). Therefore, testosterone in RSS18 cells was predominantly converted to DHT by 5alpha-reductase. Growth of RSS18 cells was stimulated by DHT (10(-11)-10(-9) M) to around 170%. By reverse transcription-polymerase chain reaction, the androgen receptor mRNA was significantly detected in RSS18 cells. As a result of these findings, DHT production from testosterone and expression of androgen receptor mRNA, we concluded that RSS18 proliferation may be stimulated by DHT through 5alpha-reductase from testosterone.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Inhibition of estradiol-17 beta secretion in ovarian granulosa cells by an extract from the submandibular gland of the rat.

The submandibular salivary gland (SMG) in the rodent is a rich source of growth factors. The estradiol-17 beta (E2) secretions were studied in the primary cultures of ovarian granulosa cells from sialoadenectomized (surgical removal of SMG, SDX) immature rats. The secretions of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were also studied in the primary cultures of anterior pituitary cells from SDX rats. E2 secretion from the ovarian granulosa cells of SDX rats was not affected by male and female SMG extracts. FSH-stimulated E2 secretion, however, was inhibited by the SMG extracts. Substances in the SMG extract, which inhibited FSH-stimulated E2 secretion in the cells, were heat and urea stable, and were not stripped by charcoal. SMG extracts did not affect the secretions of LH and FSH in the anterior pituitary cells, with or without luteinizing hormone-releasing hormone. The present findings suggest that male and female rat SMG contain the E2 modulating factor which affect ovarian granulosa cells.

Age Factors↗
PubMed1995

Evidence of gelatinase secretion by the submandibular gland in prepubescent rats.

The gelatin cleaving activities in secretions of cultured fragments of male rat submandibular glands were studied using zymography. Gelatinolytic activities of 88-, 64-, and 57-kDa proteins detected in the tissues from 22-28-day old animals were undetectable in 31-70-day old rats. The traces of gelatinolytic activity associated with 28-kDa protein were detectable from 22-day old rats in serum-free media, and this activity of the enzyme markedly increased with aging from 38-days old. At 52-days and the subsequent stages, in addition to 28-kDa, activities associated with 60-, 32-, and 29-kDa proteins were strong. When the conditioned media were treated with 1,10-phenanthroline and diisopropyl fluorophosphate (DFP), both products inhibited activity of 88-kDa enzyme, indicating that this enzyme is Cls-like enzyme. The 64- and 57-kDa activities were inhibited by 1,10-phemanthroline, but not by DFP; when the conditioned medium of the tissue from 24-day old rats was treated with p-aminophenylmercuric acetate, gelatinolytic activity associated with 64-kDa converted to 57-kDa. Therefore, 64- and 57-kDa activities were concluded to be progelatinase A and gelatinase A, respectively. On the other hand, the gelatinolytic activities associated with 60-, 32-, 29- and 28-kDa proteins were inhibited by DFP but not by 1,10-phenanthroline, indicating that these enzymes belong to the family of serine proteinase, most probably kallikrein-related enzymes. From these findings, it was suggested that gelatinase A, along with Cls-like enzyme, participates in the maturation of the submandibular gland before it becomes active as an exocrine organ.

Aging↗
PubMed1990

Androgenic actions of 5 alpha-androstane-3 alpha,17 beta-diol in rat submandibular gland.

To evaluate the action of 5 alpha-androstane-3 alpha,17 beta-diol(3 alpha-diol) in rat submandibular gland, 5 alpha-reductase, 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) and oxidative 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSDO) activities, and trypsin-like protease activities, were assayed in control, castrated and 3 alpha-diol injected rats. 3 alpha-Diol (1 mg/kg) was injected subcutaneously in castrated male rats daily for 7 days. A 47% decrease of 5 alpha-reductase activity in the nuclei and a 30% decrease of 3 alpha-HSD(O) activities in the cytosol were shown after castration. 3 alpha-Diol restored the 5 alpha-reductase and 3 alpha-HSD(O) activities to 82 and 140% of the control submandibular gland, respectively. 3 alpha-Diol raised the trypsin-like protease activity to near control values in the submandibular gland of castrated rats. Morphological observations also revealed a distinct effect of 3 alpha-diol on the number of granules of granular duct cells. It is concluded that 3 alpha-diol has an androgenic action in the rat submandibular gland. It stimulates the 3 alpha-HSD(O). The 3 alpha-HSD(O) in its turn may be responsible for DHT accumulation in the cells.

3-Hydroxysteroid Dehydrogenases↗
PubMed1990

3 alpha-hydroxysteroid dehydrogenase in the cytosol of rat submandibular gland.

We examined the in vitro shuttle metabolism between dihydrotestosterone (DHT) and 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) by 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD, E.C. 1.1.1.50) in rat submandibular gland (SMG) and ventral prostate (VP). The protein having molecular weight of 30 kDa, which was revealed by Sephacryl S-200 column chromatography, had 3 alpha-HSD activity to produce 3 alpha-diol from DHT, and also showed an oxidative 3 alpha-HSD (3 alpha-HSDO) ability to produce DHT from 3 alpha-diol. From the kinetic studies, the apparent Km and Vmax values of 3 alpha-HSD for DHT and NADPH were 6.4 microM, 1429 pmol/mg protein per min and 33.0 microM, 1205 pmol in SMG, and 9.3 microM, 377 pmol and 34.0 microM, 192 pmol in VP. The corresponding values of 3 alpha-HSDO for 3 alpha-diol and NADP+ were 18.0 microM, 714 pmol and 14.0 microM, 445 pmol in SMG, and 14.0 microM, 417 pmol and 36.0 microM, 77 pmol in VP. The affinities for DHT and 3 alpha-diol and the cosubstrate requirements of this enzyme in SMG were similar to those in VP. However, higher capacities of 3 alpha-HSD and 3 alpha-HSDO in SMG than in VP were shown. This suggests that there may be more 3 alpha-HSD in the SMG.

3-Hydroxysteroid Dehydrogenases↗
PubMed1990

Significance of 5 alpha-androstane-3 alpha, 17 beta-diol in submandibular gland.

5 alpha-Androstane-3 alpha, 17 beta-diol (3 alpha-diol) was measured in the submandibular gland (SMG) of male and female rats by radioimmunoassay (RIA) at 4 and 7 weeks of age. The raised and constant concentration of 3 alpha-diol was revealed in female SMG. The mean values of 3 alpha-diol in female SMG were found to be significantly higher than testosterone (T) and dihydrotestosterone (DHT). 3 alpha-diol in male SMG was similar to that of DHT and these two steroids decreased by the 7th week.

Androstane-3,17-diol↗
PubMed1987

Sexual difference in properties of 5 alpha-reductase in microsome of rat submandibular glands.

The properties of 5 alpha-reductase activity in the submandibular glands of rats were investigated using microsomal fraction in the presence of NADPH, and we found a sexual difference in these properties. The formation of 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 alpha, 17 beta-diol from testosterone demonstrated 5 alpha-reductase in the rat microsomal fraction of this tissue sample. Apparent michaelis constants (Km) of the 5 alpha-reductase activity for testosterone was 1.02 x 10(-6) M for the female tissue. Microsomal fraction of submandibular glands of male rats had two Kms and were determined as 1.12 x 10(-6) M and 1.01 x 10(-5) M. The lower Km of 5 alpha-reductase for male rats was similar to for the females.

Animals↗