The 5D4 antibody (anti-cyclin D1/D2) related antigen: cytoplasmic staining is correlated to the progression of gastric cancer

Immunolocalization of Keratan Sulfate in Rat Spinal Tissues Using the Keratanase Generated BKS-1(+) Neoepitope: Correlation of Expression Patterns with the Class II SLRPs, Lumican and Keratocan

This study has identified keratan sulfate in fetal and adult rat spinal cord and vertebral connective tissues using the antibody BKS-1(+) which recognizes a reducing terminal N-acetyl glucosamine-6-sulfate neo-epitope exposed by keratanase-I digestion. Labeling patterns were correlated with those of lumican and keratocan using core protein antibodies to these small leucine rich proteoglycan species. BKS-1(+) was not immunolocalized in fetal spinal cord but was apparent in adult cord and was also prominently immunolocalized to the nucleus pulposus and inner annulus fibrosus of the intervertebral disc. Interestingly, BKS-1(+) was also strongly associated with vertebral body ossification centers of the fetal spine. Immunolocalization of lumican and keratocan was faint within the vertebral body rudiments of the fetus and did not correlate with the BKS-1(+) localization indicating that this reactivity was due to another KS-proteoglycan, possibly osteoadherin (osteomodulin) which has known roles in endochondral ossification. Western blotting of adult rat spinal cord and intervertebral discs to identify proteoglycan core protein species decorated with the BKS-1(+) motif confirmed the identity of 37 and 51 kDa BKS-1(+) positive core protein species. Lumican and keratocan contain low sulfation KS-I glycoforms which have neuroregulatory and matrix organizational properties through their growth factor and morphogen interactive profiles and ability to influence neural cell migration. Furthermore, KS has interactive capability with a diverse range of neuroregulatory proteins that promote neural proliferation and direct neural pathway development, illustrating key roles for keratocan and lumican in spinal cord development.

Keratan Sulphate in the Tumour Environment

Keratan sulphate (KS) is a bioactive glycosaminoglycan (GAG) of some complexity composed of the repeat disaccharide D-galactose β1→4 glycosidically linked to N-acetyl glucosamine. During the biosynthesis of KS, a family of glycosyltransferase and sulphotransferase enzymes act sequentially and in a coordinated fashion to add D-galactose (D-Gal) then N-acetyl glucosamine (GlcNAc) to a GlcNAc acceptor residue at the reducing terminus of a nascent KS chain to effect chain elongation. D-Gal and GlcNAc can both undergo sulphation at C6 but this occurs more frequently on GlcNAc than D-Gal. Sulphation along the developing KS chain is not uniform and contains regions of variable length where no sulphation occurs, regions which are monosulphated mainly on GlcNAc and further regions of high sulphation where both of the repeat disaccharides are sulphated. Each of these respective regions in the KS chain can be of variable length leading to KS complexity in terms of chain length and charge localization along the KS chain. Like other GAGs, it is these variably sulphated regions in KS which define its interactive properties with ligands such as growth factors, morphogens and cytokines and which determine the functional properties of tissues containing KS. Further adding to KS complexity is the identification of three different linkage structures in KS to asparagine (N-linked) or to threonine or serine residues (O-linked) in proteoglycan core proteins which has allowed the categorization of KS into three types, namely KS-I (corneal KS, N-linked), KS-II (skeletal KS, O-linked) or KS-III (brain KS, O-linked). KS-I to -III are also subject to variable addition of L-fucose and sialic acid groups. Furthermore, the GlcNAc residues of some members of the mucin-like glycoprotein family can also act as acceptor molecules for the addition of D-Gal and GlcNAc residues which can also be sulphated leading to small low sulphation glycoforms of KS. These differ from the more heavily sulphated KS chains found on proteoglycans. Like other GAGs, KS has evolved molecular recognition and information transfer properties over hundreds of millions of years of vertebrate and invertebrate evolution which equips them with cell mediatory properties in normal cellular processes and in aberrant pathological situations such as in tumourogenesis. Two KS-proteoglycans in particular, podocalyxin and lumican, are cell membrane, intracellular or stromal tissue-associated components with roles in the promotion or regulation of tumour development, mucin-like KS glycoproteins may also contribute to tumourogenesis. A greater understanding of the biology of KS may allow better methodology to be developed to more effectively combat tumourogenic processes.

Effect of retinoic acid on cell proliferation and differentiation as well as on lipid synthesis, lipoprotein secretion, and apolipoprotein biogenesis

Dietary vitamin A and its active metabolites are essential nutrients for many functions as well as potent regulators of gene transcription and growth. Although the epithelium of the small intestine is characterized by rapid and constant renewal and enterocytes play a central role in the absorption and metabolism of alimentary retinol, very little is known about the function of retinoids in the human gastrointestinal epithelium and mechanisms by which programs engage the cell cycle are poorly understood. We have assessed the effects of 10 microM 9- and 13-cis-retinoic acid (RA) on proliferation and differentiation processes, lipid esterification, apolipoprotein (apo) biogenesis and lipoprotein secretion along with nuclear factor gene transcription. Treatment of Caco-2 cells with RA at different concentrations and incubation periods revealed the reduction of thymidine incorporation in 60% preconfluent or 100% confluent cells. Concomitantly, RA 1) modulated D-type cyclins by reducing the mitogen-sensitive cyclin D1 and upregulating cyclin D3 expressions and 2) caused a trend of increase in p38 MAPK, which triggers CDX2, a central protein in cell differentiation. RA remained without effect on lipoprotein output and apo synthesis, even for apo A-I that possesses RARE in its promoter. RA, in combination with 22-hydroxycholesterol, could induce apo A-I gene expression without any impact on apo A-I mass. Only the gene expression of peroxisome proliferator-activated receptor (PPAR)beta, retinoic receptor (RAR)beta, and RARgamma was augmented and no alteration was noted in PPARalpha, PPARgamma, liver X receptor (LXR)alpha, LXRbeta, and retinoid X receptors. Taken together, these data highlight RA-induced cell differentiation via specific signaling without a significant impact on apo A-I synthesis.

Alterations of the CCND1 and HER-2/neu (ERBB2) proteins in esophageal and gastric cancers

We evaluated the relationship of amplification and polysomy of both the CCND1 and the ERBB2 (alias HER-2/NEU) genes to the overexpression of their proteins in esophageal and gastric cancers and also their association with clinicopathological features. CCND1 gene amplification (45%) was more prevalent than polysomy (25%) in esophageal carcinoma, but the pattern observed was similar in gastric adenocarcinoma (10% amplification, 15% polysomy). For ERBB2, polysomy was a more frequent mechanism than amplification in both esophageal (32.5 vs. 7.5%) and gastric (15 vs. 5%) cancers. Overexpression of cyclin D1 protein was identified in 37.5% of the specimens of esophageal tumors and 35% of gastric tumors, and overexpression of Her-2/neu protein in 12.5 and 7.5%, respectively. The kappa-statistics revealed a fair agreement in both types of tumors only in overexpression and amplification of the CCND1 gene; the ERBB2 gene showed a fair agreement in amplification and polysomy and the level of protein expression in gastric adenocarcinoma. Thus, polysomy 17 could contribute to a high Her-2/neu protein level, at least in gastric cancer. Our data indicated an association with alcohol consumption and the CCND1 gene or protein levels, in both esophageal and gastric cancers.

Expression of D-type cyclins in colon cancer and in cell lines from colon carcinomas

Cyclins D1, D2 and D3 play important roles in cell proliferation and differentiation. Although their abnormal expression has been linked to cancer development and progression in a number of tissues, the expression of cyclin D2 and D3 proteins in colon cancer has not yet been characterised. In this study, we examined cyclin D1, D2 and D3 protein expression by Western blot analysis in tumour and adjacent normal colon tissues of 57 patients. In addition, we examined D-type cyclins protein expression in HT29 and LoVo39 cell lines from colon carcinomas, as a function of induced proliferation and differentiation. In both cell lines, the expression of the three D-type cyclins increased as a result of induced proliferation, whereas the expression of cyclin D3 increased as a result of induced differentiation. In colon tumours, cyclin D1 was overexpressed in 44%, cyclin D2 was overexpressed in 53% and cyclin D3 was overexpressed in 35% of the cases. We also found that in 16% of the cases, cyclin D3 protein expression was reduced in the tumour, as compared to the adjacent normal tissue. Examination of D-type cyclin protein overexpression in relation to the TNM stage of the tumours revealed that overexpression of cyclins D1 and/or D2, but not cyclin D3, is linked to colon carcinogenesis and that overexpression of cyclin D2 may be related to a higher TNM stage of the tumour.

Absence of cyclin D2 expression is associated with promoter hypermethylation in gastric cancer

Expression of cyclin D2 is absent in 30-70% of gastric cancers. We investigated the role of promoter hypermethylation in the transcriptional silencing of cyclin D2 in five gastric cell lines and 47 primary gastric carcinomas. CpG island methylation status of the cyclin D2 gene was studied by methylation-specific polymerase chain reaction and bisulphite sequencing. RNA and protein expression was analysed by reverse transcription-PCR and Western blot, respectively. Dense methylation of cyclin D2 was detected in three cell lines (KATOIII, AGS and NCI-N87), which also lacked cyclin D2 mRNA and protein expression. Bisulphite DNA sequencing revealed that loss of cyclin D2 expression was closely associated with the density of methylation in the promoter region. Treatment with DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, restored the cyclin D2 expression level in methylated gastric cells. Among the 47 primary gastric cancers, cyclin D2 hypermethylation was detected in 23 (48.9%) cases. None of the 23 normal gastric biopsies from noncancer patients showed hypermethylation. Hypermethylation was associated with loss of mRNA (P&<0.001) and protein (P=0.006) expressions. Our study showed that cyclin D2 hypermethylation is associated with loss of cyclin D2 expression in a subset of gastric cancers, which may suggest an alternative gastric carcinogenesis pathway in the absence of cyclin D2 expression.

Cdk4 deficiency inhibits skin tumor development but does not affect normal keratinocyte proliferation

Most human tumors have mutations that result in deregulation of the cdk4/cyclin-Ink4-Rb pathway. Overexpression of D-type cyclins or cdk4 and inactivation of Ink4 inhibitors are common in human tumors. Conversely, lack of cyclin D1 expression results in significant reduction in mouse skin and mammary tumor development. However, complete elimination of tumor development was not observed in these models, suggesting that other cyclin/cdk complexes play an important role in tumorigenesis. Here we described the effects of cdk4 deficiency on mouse skin proliferation and tumor development. Cdk4 deficiency resulted in a 98% reduction in the number of tumors generated through the two-stage carcinogenesis model. The absence of cdk4 did not affect normal keratinocyte proliferation and both wild-type and cdk4 knockout epidermis are equally affected after topical treatment with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), resulting in epidermal hyperplasia. In similar fashion, cdk4 knockout keratinocytes proliferated well in an in vivo model of wound-induced proliferation. Biochemical studies in mouse epidermis showed that cdk6 activity increased twofold in cdk4-deficient mice compared to wild-type siblings. These results suggest that therapeutic approaches to inhibit cdk4 activity could provide a target to inhibit tumor development with minimal or no effect in normal tissue.

Cyclin D2 overexpression in transgenic mice induces thymic and epidermal hyperplasia whereas cyclin D3 expression results only in epidermal hyperplasia

In a previous report, we described the effects of cyclin D1 expression in epithelial tissues of transgenic mice. To study the involvement of D-type cyclins (D1, D2, and D3) in epithelial growth and differentiation and their putative role as oncogenes in skin, transgenic mice were developed which carry cyclin D2 or D3 genes driven by a keratin 5 promoter. As expected, both transgenic lines showed expression of these proteins in most of the squamous tissues analyzed. Epidermal proliferation increased in transgenic animals and basal cell hyperplasia was observed. All of the animals also had a minor thickening of the epidermis. The pattern of expression of keratin 1 and keratin 5 indicated that epidermal differentiation was not affected. Transgenic K5D2 mice developed mild thymic hyperplasia that reversed at 4 months of age. On the other hand, high expression of cyclin D3 in the thymus did not produce hyperplasia. This model provides in vivo evidence of the action of cyclin D2 and cyclin D3 as mediators of proliferation in squamous epithelial cells. A direct comparison among the three D-type cyclin transgenic mice suggests that cyclin D1 and cyclin D2 have similar roles in epithelial thymus cells. However, overexpression of each D-type cyclin produces a distinct phenotype in thymic epithelial cells.