A sensitive radioimmunoassay (RIA) for the determination of inhibin in peripheral plasma and tissue homogenates of different species has been developed using antisera to partially purified bovine follicular fluid (bFF) inhibin and 125I-labelled bFF 32 kDa inhibin. Antisera were produced by immunization of rabbits with partially purified bFF inhibin prepared by immunoaffinity chromatography. Increasing doses of a high titre antiserum could neutralize the suppressing effect of bFF, porcine follicular fluid and rat ovarian homogenate on FSH secretion from rat anterior pituitary cells in culture. Sensitivity of the assay was 3.1 ng International Research Standard of porcine inhibin per tube. Parallel inhibition curves were obtained for inhibin preparations from female and male animals of ten species, i.e. cattle, goats, sheep, cats, dogs, monkeys, pigs, horses, rats and man. Inhibin subunits and related proteins cross-reacted minimally with the antiserum used in the study. Plasma concentrations of inhibin in adult male and female rats were measured by the RIA before and at various times after gonadectomy. Inhibin levels in peripheral plasma before gonadectomy were significantly higher in adult female than in adult male rats. Inhibin levels decreased abruptly after gonadectomy in both sexes and they correlated negatively with plasma concentrations of FSH. This inhibin RIA will facilitate studies of the physiology of inhibin in various species of animals.

Novel methotrexate (MTX) derivatives bearing dihydro-2H-1,4-benzothiazine or dihydro-2H-1,4-benzoxazine were synthesized and tested for in vitro antiproliferative activities against human synovial cells (hSC) and human peripheral blood mononuclear cells (hPBMC) obtained from patients with rheumatoid arthritis and healthy volunteers, respectively. In vivo antiarthritic activities of these derivatives were also evaluated in a rat adjuvant arthritis model. N-[[4-[(2,4-Diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzothiazin-7-yl]carbonyl]-L-glutamic acid (3c) exhibited more potent antiproliferative activities in hSC and hPBMC than MTX in vitro. Antiproliferative activities of N-[[4-[(2,4-diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzoxazin-7-yl]carbonyl]-L-homoglutamic acid (3b) and N-[[4-[(2,4-diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzothiazin-7-yl]carbonyl]-L-homoglutamic acid (3d) (MX-68) were comparable to that of MTX in these in vitro assays. Compounds 3b,d (MX-68) significantly suppressed progression of the adjuvant arthritis in a dose-dependent manner ranging from 0.5 to 2.5 mg/kg (po). In addition, 3d (MX-68) completely suppressed this progression at the dose of 2.5 mg/kg (po). Importantly, 3d (MX-68) having benzothiazine and homoglutamate, as expected, did not undergo polyglutamation, a process which may be responsible for the associated side effects of MTX. These results suggest that 3d (MX-68) is a potent and safe candidate antirheumatic agent, absent of the side effects of MTX.

Inhibitor of growth 2 (ING2) is associated with chromatin remodeling and regulation of gene expression by binding to a methylated histone H3K4 residue and recruiting HDAC complexes to the region. The aim of our study is to investigate the regulation of ING2 expression and the clinical significance of upregulated ING2 in colon cancer. Here, we show that the ING2 mRNA level in colon cancer tissue increased to more than twice than that in normal mucosa in the 45% of colorectal cancer cases that we examined. A putative NF-jB binding site was found in the ING2 promoter region. We confirmed that NF-jB could bind to the ING2 promoter by EMSA and luciferase assays. Subsequent microarray analyses revealed that ING2 upregulates expression of matrix metalloproteinase 13 (MMP13), which enhances cancer invasion and metastasis. Inhibitor of growth 2 (ING2), which is a member of ING gene family, was identified by searching EST databases for any similarity to the ING1 gene. A previous report has shown that the ING2 mRNA is expressed in testis at the highest level among normal tissues, and also emphasizes that ING2 mRNA expression is remarkably increased in colon cancer tissue compared to nonmalignant tissue.2 ING2 as well as ING1b are considered to be candidate tumor suppressor genes, which cooperate with p53 and share many biological functions, such as apoptosis, cell cycle regulation and senescence.3-7 Our recent report has shown that ING2 expression is suppressed by nutlin-3a-induced p53, resulting in the induction of senescence in normal human fibroblasts and a cancer cell line.8 ING family proteins functionally form complexes with several factors possessing intrinsic histone acetyltransferase (HAT) and histone deacetylase complex (HDAC) activities, thus, linking the function of ING genes to chromatin remodeling and transcriptional regulation through histone modifications.9-15 Among ING proteins, ING2 especially has a potential ability to bind to the trimethylated histone H3 at lysine 4 (H3K4me3). H3K4me3 correlates with transcriptional activation, while methylations occurred at many other histone residues are associated with transcriptional suppression. [16][17][18] Previous reports suggest that ING2 only induces gene expression and does not repress expression of any known genes in normal fibroblasts. 19ING2 also interacts with phosphatidylinositol 5-phosphate (PtdIns5P). 20,21 PtdIns5P, which may function in a nuclear signaling pathway, has been implicated as a critical regulator of nuclear signaling events during cell-cycle progression.22,23 Cellular stress, such as UV irradiation or oxidative stress, causes the accumulation of nuclear PtdIns5P, resulting in the activation of ING2. 24,25 Oxidative and nitrosative stress are linked with inflammation-associated cancer including colon carcinoma. 26 We report here evidence that pathophysiological expression of ING2 may enhance invasion and metastasis of colon cancer by increasing the expression of MMP13. Material and methods Clinical samples and RNA extractionFive colorectal...

Ubiquitin-like with PHD and ring-finger domain 1 (UHRF1) binds to methylated promoters of a number of tumor-suppressor genes, including p16INK4A and p14ARF, by forming complexes with DNA methyltransferases and HDAC1, resulting in the induction of carcinogenesis. Altered UHRF1 expression has been demonstrated in various types of cancers. Previous reports indicate that UHRF1 expression is regulated by E2F-1 expression. We investigated UHRF1 expression using immunohistochemical staining in 231 colorectal cancer and 40 adenoma specimens, analyzed the relationship between UHRF1 expression and clinicopathological findings and the association between UHRF1 and E2F-1 expression. To better understand the biological function of UHRF1 in colorectal cancer, knockdown of UHRF1 expression was performed using siRNA methods. High UHRF1 expression was observed in 152 of 231 (65.8%) colorectal cancer patients, and was detected in 35 of 40 adenoma specimens samples (87.5%). UHRF1 staining was detected in the nucleus of cancer cells, while it was not detected in colonic normal mucosa. High UHRF1 expression was significantly observed in right compared with left hemicolon cancer (p=0.008). Moreover, high UHRF1 expression tended to be associated with depth of invasion (p=0.051). UHRF1 expression was significantly associated with E2F-1 expression (p<0.0001). Knockdown of UHRF1 expression suppressed cellular growth in colon cancer cell lines, HCT116 and SW620. In conclusion, we demonstrated that UHRF1 expression was upregulated in approximately two-thirds of colorectal cancer specimens and was particularly expressed in right compared with left hemicolon cancer. Moreover, knockdown of UHRF1 expression induced growth inhibition in colon cancer cell lines. UHRF1 may be involved in cellular proliferation and molecular pathogenesis of colorectal cancer in the right hemicolon.

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