Galactosyl receptor, a cell surface C-type lectin of normal and tumoral prostate epithelial cells with binding affinity to endothelial cells

Prostate Cancer Progression and Surrounding Microenvironment

Bidirectional cellular interactions between prostate cancer and prostate or bone stroma are needed for local tumor growth and distant metastasis. The genetics of cancer cells is affected by the host microenvironment and, reciprocally, permanent gene expression changes occur in the stroma surrounding epithelial cancer cells. The immune-mediated micromilieu also affects the progression of prostate cancer; the role of the immune system in controlling the growth of prostate cancer cells is complex, with immune escape mechanisms prevailing over effective antitumor response. Moreover, tumor stem cell models to explain the origin and progression of prostate cancer require appropriate environmental conditions. On the basis of a review of the literature, this article aims to outline the recent advances in the elucidation of the molecular mechanisms underlying the interactions between prostate cancer and its microenvironment.

Influence of beta-galactose-specific mitochondrial lectins from prostate hyperplasic tissue on mitochondrial properties

Galactose-specific lectins (Gal-lectins) were isolated from the mitochondrial fraction of prostate post-operational hyperplasic tissue of two diagnoses: benign prostate hyperplasic tissue with low-grade intraepithelial neoplasia (LGPIN) and benign prostate hyperplasic tissue with atypical adenomatous hyperplasia (AAH). They had similar molecular weight and other properties. Effects of these lectins were investigated in vitro model experiments on bovine liver cells mitochondrial properties. Time-dependent changes: (i) in the amount of H(2)O(2); (ii) redox state of Cu in cytochrome oxidase and (iii) redox state of heme in cytochrome a+a(3) (cyt a+a(3)) of cytochrome c oxidase complex were studied. Gal-lectins from both sources increase the amount of H(2)O(2) and decrease the redox state of Cu in cytochrome oxidase and heme in cyt a+a(3). However the Gal-lectin from tissue with more severed transformation (AAH) expresses significantly more strong and long-lasting influence. These effects are mediated by galactose binding domain of the lectins as are completely abolished by the inclusion of galactose in reaction medium. Accumulation of H(2)O(2) and long-lasting decrease in the redox state of key enzymes of mitochondrial respiration chain could induce defective functioning of these organelles and whole cells. Obtained data point the possible way, which enhances further transformation of prostate tissue by release of Gal-lectins from damaged mitochondria.

Novel surface expression of reticulocalbin 1 on bone endothelial cells and human prostate cancer cells is regulated by TNF-alpha

An unbiased cDNA expression phage library derived from bone-marrow endothelial cells was used to identify novel surface adhesion molecules that might participate in metastasis. Herein we report that reticulocalbin 1 (RCN1) is a cell surface-associated protein on both endothelial (EC) and prostate cancer (PCa) cell lines. RCN1 is an H/KDEL protein with six EF-hand, calcium-binding motifs, found in the endoplasmic reticulum. Our data indicate that RCN1 also is expressed on the cell surface of several endothelial cell lines, including human dermal microvascular endothelial cells (HDMVECs), bone marrow endothelial cells (BMEC), and transformed human bone marrow endothelial cells (TrHBMEC). While RCN1 protein levels were highest in lysates from HDMVEC, this difference was not statistically significant compared BMEC and TrHBMEC. Given preferential adhesion of PCa to bone-marrow EC, these data suggest that RCN1 is unlikely to account for the preferential metastasis of PCa to bone. In addition, there was not a statistically significant difference in total RCN1 protein expression among the PCa cell lines. RCN1 also was expressed on the surface of several PCa cell lines, including those of the LNCaP human PCa progression model and the highly metastatic PC-3 cell line. Interestingly, RCN1 expression on the cell surface was upregulated by tumor necrosis factor alpha treatment of bone-marrow endothelial cells. Taken together, we show cell surface localization of RCN1 that has not been described previously for either PCa or BMEC and that the surface expression on BMEC is regulated by pro-inflammatory TNF-alpha.

The metastatic cascade in prostate cancer

Morbidity and mortality due to prostate cancer are mainly a result of prostate cancer metastases. After the initial neoplastic transformation of cells, the process of metastasis involves a series of sequential steps, which involve neoangiogenesis and lymphangiogenesis, loss of adhesion with migration away from the primary tumour and entry into the systemic vasculature or lymphatics. Metastatic growth in sites such as lymph nodes and bone marrow then involves the specific non-random homing of prostate cancer cells. An appreciation and understanding of this metastatic cascade in relation to prostate cancer is clinically important in order to stratify men with prostate cancer into prognostic groups. Moreover, it is crucial in the future development of therapies that can prevent metastases.

Stromal factors involved in prostate carcinoma metastasis to bone

BACKGROUND

Prostate carcinoma (PC) frequently metastasizes to bone, where it causes significant morbidity and mortality. Stromal elements in the primary and metastatic target organs are important mediators of tumor cell intravasation, chemoattraction, adhesion to target organ microvascular endothelium, extravasation, and growth at the metastatic site.

METHODS

The role of stromal factors in bone metastasis was determined with a cyclic DNA microarray comparison of a bone-derived cell PC cell line with a soft tissue-derived cell PC cell line and by evaluating the effects of selected stromal components on PC cell chemotaxis, cell adhesion to human bone marrow endothelium (HBME), and PC cell growth.

RESULTS

The authors demonstrate that PC cells express protease-activated receptor 1 (PAR1; thrombin receptor), and its expression is up-regulated in PC compared with normal prostate tissue. In addition, this overexpression was very pronounced in bone-derived PC cell lines (VCaP and PC-3) compared with soft tissue PC cell lines (DUCaP, DU145, and LNCaP). The authors report that bone stromal factors, including stromal cell-derived factor 1 (SDF-1) and collagen Type I peptides, are chemoattractants for PC cells, and they demonstrate that some of these factors (e.g., extracellular matrix components, transforming growth factor beta, bone morphogenic proteins [BMPs], and SDF-1) significantly alter PC-HBME interaction in vitro. Finally, stromal factors, such as BMPs, can regulate the proliferation of PC cells in vitro.

CONCLUSIONS

Soluble and insoluble elements of the stroma are involved in multiple steps of PC metastasis to bone. The authors hypothesize that PAR1 may play a central role in prostate tumorigenesis.

Molecular characterization of the murine SIGNR1 gene encoding a C-type lectin homologous to human DC-SIGN and DC-SIGNR

The C-type lectin human dendritic cell (DC)-specific intercellular adhesion molecule (ICAM)-3-grabbing non-integrin (DC-SIGN) plays important roles in pattern recognition by dendritic cells in the immune system. In addition to binding human immunodeficiency virus (HIV), this type II membrane protein binds with high affinity to the adhesion molecules ICAM-3 and -2 to promote important dendritic cell interactions with naive T cells and endothelial cells, respectively. DC-SIGNR, a human DC-SIGN homologue expressed on sinusoidal endothelial cells in liver and lymph node, also binds and transmits HIV virus. We describe the cloning and characterization of a family of murine complementary DNAs (cDNAs) called SIGNR1, expressed in skin and spleen, that encode C-type lectins highly related to human DC-SIGN and DC-SIGNR. We also report the genomic structure of the SIGNR1 gene and compare it to that of human DC-SIGN and DC-SIGNR. The different transcripts (alpha, beta, gamma, delta) are generated by differences in 5' untranslated sequences, alternative splicing and/or the use of different polyadenylation sites. The predicted open reading frames encoded by the cDNAs are most closely related to human DC-SIGN and DC-SIGNR in the cytoplasmic domain, the transmembrane region and the carbohydrate recognition domain. Moreover, the alternatively spliced transcripts encode proteins that lack the transmembrane region or have modified carbohydrate recognition domains. Northern hybridization experiments with several different SIGNR1 cDNA probes reveal transcripts of 1.3 and 2.1 kb that are expressed in a tissue-restricted fashion in murine skin, spleen and lung. In situ hybridization and immunocytochemistry experiments demonstrate that, like human DC-SIGN, the murine messenger RNAs are expressed in subsets of dendritic cells in the spleen and skin.

Mechanisms governing bone metastasis in prostate cancer

Why does prostate cancer metastasize to bone? Why is there increased turnover of the bone matrix in the presence of prostate cancer? A recent autopsy study supports a traditional hypothesis that gross, anatomic patterns of blood flow influence the distribution of metastatic deposits. On the other hand, recent developments in animal models of prostate cancer bone metastasis have renewed interest in the traditional 'seed and soil' hypothesis: several studies point to specific biological interactions between prostate cancer cells and the bone microenvironment that can explain the tendency of prostate cancer cells to colonize bone and grow into clinically relevant metastatic deposits. Some studies implicate mechanisms including chemoattraction and enhanced adherence to bone endothelium. Additional data suggest that prostate cancer cells are 'osteomimetic', that is, they take on the properties and behaviors of osteoblasts or osteoclasts upon arrival in bone. These activities lead to enhanced turnover of the bone matrix and may explain the propensity of prostate cancer to grow in bone. Finally, a series of studies have implicated other molecular markers as distinguishing characteristics of bone-metastatic prostate cancer tissue.

Biological characteristics of lactosaminated N-succinyl-chitosan as a liver-specific drug carrier in mice

Lactosaminated N-succinyl-chitosan (Lac-Suc) was prepared by reductive amination of N-succinyl-chitosan (Suc) and lactose using sodium cyanoborohydride. Six-day reaction using lactose (12.8-fold (w/w)) yielded Lac-Suc with lactosamination degree of 30% (mol/sugar unit). Fluorescein thiocarbamyl-Lac-Suc (Lac-Suc-FTC) was prepared by labeling Lac-Suc with fluorescein isothiocyanate. Lac-Suc-FTC was injected intravenously at a dose of either 1 (high dose) or 0.2 (low dose) mg/mouse. At both doses, Lac-Suc-FTC initially underwent fast hepatic clearance, showed maximum liver localization at 8 h, and the amounts localized there were maintained even at 48 h post-injection. Very slow excretion into feces and urine was observed. The ratio of liver AUC(0--48 h) to plasma AUC(0--48 h) at low dose was three times higher than that at high dose. On the other hand, the Suc derivative, Gal-Suc, obtained by reductive amination of Suc/galactose showed very little distribution to the liver similarly to Suc itself. Further, since the liver uptake of Lac-Suc-FTC was inhibited by asialofetuin, it was suggested that the liver distribution of Lac-Suc should be concerned with asialoglycoprotein receptor. Thus, Lac-Suc was found available as a carrier exhibiting a high affinity to and long retention in the liver.