Role of SPan-1 antigen in adhesion of human colon cancer cells to vascular endothelium

SPan-1 is a useful prognostic marker for patients with stage IV gastric cancer who underwent palliative gastrectomy: a retrospective multivariate study

BACKGROUND

We retrospectively investigated prognostic factors to be used in selecting the patients with stage IV gastric cancer (GC) who have an unfavorable prognosis after palliative gastrectomy.

METHODS

A total of 146 GC patients at stage IV who had undergone palliative gastrectomy were enrolled. Various clinicopathological parameters were evaluated for prognosis.

RESULTS

Surgical morbidity and hospital mortality occurred in 35 (23.9 %) and 4 (2.7 %) patients, respectively. The overall 5-year survival rate and the median survival time were 11.2 % and 13.2 months, respectively. Of the 146 patients, 64 had uncomfortable symptoms associated with GC and 76 had no such symptoms. Of the 64 patients with uncomfortable symptoms, 60 (93.7 %) experienced relief of these symptoms after palliative surgery. Multivariate analysis for patients without uncomfortable symptoms associated with GC revealed that the number of incurable factors and serum SPan-1 level were independent prognostic factors.

CONCLUSIONS

Patients with stage IV GC who had multiple incurable factors and a high level of serum SPan-1 might not be candidates for palliative gastrectomy for the purpose of prognostic benefit.

Carbohydrate recognition by boronolectins, small molecules, and lectins

Carbohydrates are known to mediate a large number of biological and pathological events. Small and macromolecules capable of carbohydrate recognition have great potentials as research tools, diagnostics, vectors for targeted delivery of therapeutic and imaging agents, and therapeutic agents. However, this potential is far from being realized. One key issue is the difficulty in the development of "binders" capable of specific recognition of carbohydrates of biological relevance. This review discusses systematically the general approaches that are available in developing carbohydrate sensors and "binders/receptors," and their applications. The focus is on discoveries during the last 5 years.

Mechanisms by which E-selectin regulates diapedesis of colon cancer cells under flow conditions

Diapedesis, the passage of circulating tumor cells across the endothelium, is a critical determinant in most cases of metastasis. Using a laminar flow chamber and a tissue-engineered blood vessel, we found that E-selectin is required not only for the initial adhesion and rolling of circulating HT-29 colon cancer cells on the endothelium but also for their subsequent diapedesis. These processes require both the intracellular and extracellular domains of E-selectin. We also identified three distinct mechanisms by which circulating cancer cells interact with E-selectin to initiate their diapedesis: formation of a mosaic between cancer cells and endothelial cells, paracellular diapedesis at the junction of three endothelial cells, and transcellular diapedesis. We also obtained evidence indicating that E-selectin-dependent paracellular extravasation is independent of intercellular adhesion molecule and vascular cell adhesion molecule and that it requires the activation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase downstream of E-selectin. This is supported by the observation that the adenoviral-mediated expression of the E-selectin mutant Y603F is associated with both an inhibition of ERK and paracellular extravasation. Our study is the first to clearly establish, under dynamic and shear stress conditions, how E-selectin regulates diapedesis of circulating cancer cells. These results provide new insights in understanding the metastatic process.

Targeting selectins and selectin ligands in inflammation and cancer

Inflammation and cancer metastasis are associated with extravasation of leukocytes or tumor cells from blood into tissue. Such movement is believed to follow a coordinated and sequential molecular cascade initiated, in part, by the three members of the selectin family of carbohydrate-binding proteins: E-selectin (CD62E), L-selectin (CD62L) and P-selectin (CD62P). E-selectin is particularly noteworthy in disease by virtue of its expression on activated endothelium and on bone-skin microvascular linings and for its role in cell rolling, cell signaling and chemotaxis. E-selectin, along with L- or P-selectin, mediates cell tethering and rolling interactions through the recognition of sialo-fucosylated Lewis carbohydrates expressed on structurally diverse protein-lipid ligands on circulating leukocytes or tumor cells. Major advances in understanding the role of E-selectin in inflammation and cancer have been advanced by experiments assaying E-selectin-mediated rolling of leukocytes and tumor cells under hydrodynamic shear flow, by clinical models of E-selectin-dependent inflammation, by mice deficient in E-selectin and by mice deficient in glycosyltransferases that regulate the binding activity of E-selectin ligands. Here, the authors elaborate on how E-selectin and its ligands may facilitate leukocyte or tumor cell recruitment in inflammatory and metastatic settings. Antagonists that target cellular interactions with E-selectin and other members of the selectin family, including neutralizing monoclonal antibodies, competitive ligand inhibitors or metabolic carbohydrate mimetics, exemplify a growing arsenal of potentially effective therapeutics in controlling inflammation and the metastatic behavior of cancer.

Effect of extended conjugation with a phenylethynyl group on the fluorescent properties of water-soluble arylboronic acids

Boronic acids that change fluorescent properties upon sugar binding are very important reporter units for the development of small molecule lectin mimics (boronolectins). Aimed at developing long wavelength fluorescent boronic acid reporter compounds, we have designed and synthesized a series of boronic acid analogs 2a-d with an extended π conjugation. Such designs are based on earlier fluorescent boronic acids that change fluorescent properties upon sugar binding. Compared with the corresponding parent chromophores, these new compounds with extended conjugations show longer excitation and emission wavelengths as designed. The patterns of fluorescent changes for the new compounds are also different from that of the corresponding parent compounds.

Regulation of transendothelial migration of colon cancer cells by E-selectin-mediated activation of p38 and ERK MAP kinases

The invasive properties of cancer cells depend on their intrinsic motile potential and on their ability to breach the endothelial barrier. In the present work, we investigated the mechanisms by which adhesion of colon cancer cells to E-selectin expressed by endothelial cells regulates the barrier function of these cells and modulates transmigration of cancer cells. We found that the stimulation of E-selectin by activating antibodies or the adhesion of HT-29 cells results in an increase in the activity of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinases. In turn, the activation of p38 and ERK enhances transendothelial permeability and migration of HT-29 cells. We also obtained evidence suggesting that p38-mediated increase in transendothelial migration of cancer cells depends on a myosin light chain phosphorylation-mediated formation of stress fibres. On the other hand, the activation of ERK by E-selectin modulates the opening of interendothelial spaces by initiating the activation of Src kinase activities and the dissociation of the VE-cadherin/beta-catenin complex. We conclude that activation of E-selectin by adhering cancer cells is an important process that regulates the extravasation of colon cancer cells by initiating p38- and ERK-dependent mechanisms that both contribute to regulate the integrity of the endothelial layer.

Influence of proinflammatory cytokines on the adhesion of human colon carcinoma cells to lung microvascular endothelium

In this experimental study, the influence of surgery-induced proinflammatory cytokines on tumor recurrence in the lung was investigated. A reproducible human in vitro assay was developed to study the adhesion of HT29 colon carcinoma cells to monolayers of microvascular endothelial cells of the lung (HMVECs-L) or human umbilical venous endothelial cells (HUVECs). Preincubation of HMVECs-L with maximally active concentrations of IL-1beta and TNF-alpha, but not with IL-6, resulted in at least 250% adhesion compared to control adhesion (p <or= 0.01). The effect of IL-1beta and TNF-alpha was concentration- and time-dependent. Comparable results were found for HUVECs. Tumor cell adhesion was not increased after preincubation of HT29 with TNF-alpha. Enzyme immunoassays of cytokine-preincubated HUVECs and HMVECs-L showed concentration- and time-dependent upregulation of E-selectin, ICAM-1 and VCAM-1 expression. In addition, LFA-1 and VLA-4 were only expressed on HMVECs-L, creating more binding possibilities for HMVECs-L compared to HUVECs. Inhibition assays with anti-E-selectin monoclonal antibody significantly decreased tumor cell adhesion to HUVECs; however, it did not affect tumor cell adhesion to HMVECs-L. Furthermore, anti-ICAM-1 and anti-VCAM-1 antibodies did not affect adhesion. Our results prove IL-1beta and TNF-alpha promote tumor cell adhesion to HMVECs-L in vitro and may therefore account for enhanced tumor recurrence in the lung seen after major surgical trauma. The adhesion of HT29 to HUVEC is inhibitable by E-selectin antibodies, whereas the adhesion to HMVEC-L is not inhibitable by these antibodies. Probably not one but a complex of adhesion molecules is responsible for enhanced adhesion to HMVECs-L.

Are selectins involved in metastasis?

The selectins are a family of intercellular adhesion molecules that mediate the attachment of leukocytes to the endothelial lining of blood vessels. Another biological process that may involve selectins is the adhesion of circulating tumour cells to endothelium in cancer metastasis. This review discusses the evidence for the involvement of E-, P- and L-selectin in the metastasis of different tumour types. It is concluded that, with certain reservations and qualifications, selectins can play a role in metastasis. For example, the evidence for the involvement of E-selectin in breast and colon cancer metastasis is very strong. For the other selectins and tumour types the evidence is less convincing and further investigations are required to clarify the situation. Certainly, selectins are not the only mechanism available for tumours to metastasise. In the future, measurement of selectins could be useful prognostically and manipulation of their levels could lead to new cancer therapies.

Differential motility stimulation but not growth stimulation or adhesion of metastatic human colorectal carcinoma cells by target organ-derived liver sinusoidal endothelial cells

Liver is the most common distant metastatic site for colorectal cancers and when blood-borne colorectal cancer cells reach the liver, they first encounter hepatic capillary and sinusoidal endothelial cells. Thus we studied differences between highly (HT-29LMM) and poorly (HT-29P) liver-metastatic sublines of human colorectal cancer cells by examining the interactions between tumor cells and liver microvessel endothelial cells. Using hepatic sinusoidal endothelial (HSE) and lung microvessel endothelial (MLE) cell-conditioned medium we measured the growth and motility stimulating activities released from these endothelial cells and adhesion of these cancer cells to the endothelial cells. Differences in the ability of HSE-conditioned medium (HSE-CM) or MLE-conditioned medium (MLE-CM) to stimulate HT-29 cell growth were not observed. There was a small but significant increase in the rate of adhesion of highly metastatic HT-29LMM cells to HSE cell monolayers than poorly metastatic HT-29P cells, but there was no difference in adhesion to MLE cell monolayers. HSE-CM stimulated the motility of highly metastatic colorectal cancer cells to a greater extent than the poorly metastatic cells. Motility-stimulating activity for the colorectal cancer cell lines was not detected in MLE-CM. The HSE-CM motility-stimulating activity for human HT-29 cells was not removed using antibodies against hepatocyte growth factor (HGF/SF), complement component C3 or laminin, indicating that it is not related to these known liver-derived motility factors. The results suggest that the ability of highly metastatic HT-29LMM colorectal cancer cells to colonize the liver is related to their ability to respond to liver sinusoidal endothelial cell-derived motility factors and to a lesser degree to adhere to liver sinusoidal endothelial cells.