1Department of Bioengineering and 2The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania
Submitted 3 September 2004 ; accepted in final form 12 December 2004
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
neutrophil; melanoma; shear stress; shear rate; 2-integrins; intracellular adhesion molcule-1; CXCR1/2; adhesion; migration
It is evident from in vivo studies (5, 12, 17, 28) that the mechanisms utilized by leukocytes and metastatic tumor cells to adhere to a vessel wall before extravasation are different. An in vivo study (17) showed that under a shear flow, B16F1 melanoma cells could arrest on the walls of presinusoidal vessels in mice when pretreated with interleukin-1 (IL-1
). This suggests the release of cytokines into the bloodstream could result in melanoma cell arrest in portal venules by chemoattraction and adhesion rather than by size restriction only.
Welch et al. (24) showed C8161 melanoma cells are a metastatic model that is both highly invasive compared with other well-characterized melanoma cell lines and spontaneously metastatic by tail-vein injection in nude mice. Melanoma cells do not express 2-integrins, Sialyl Lewis X (SLex) or other sialylated molecules at an effective level (6, 19). In contrast, the C8161 cell line expresses basal levels of intracellular adhesion molecule-1 (ICAM-1) that can be upregulated with TNF-
treatment (19). Tumor cell lines of various tissue origins also express ICAM-1 (e.g., A2058, WM9, and MDA-MB-435) (24, and personal observations). Whereas metastatic potential of melanoma cell lines does not correlate directly with ICAM-1 expression, C8161 cells express ICAM-1 in the low range of tested melanoma cells (24).
Currently little is known about specific interactions of PMN-melanoma heterotypic aggregation in a shear flow. Some recent studies (8, 10, 11, 15) have quantified the strength and kinetic properties of lymphocyte function-associated antigens (LFA-1; CD11a/CD18; L
2) and Mac-1 (CD11b/CD18;
M
2) binding in PMN homotypic (e.g., PMNs to PMNs) and heterotypic (e.g., PMNs to cells expressing ICAM-1) aggregation, especially under a hydrodynamic shear force over the time course of chemotactic stimulation. Studies by Neelamegham et al. (15) and Hentzen et al. (8) suggest that LFA-1 binding to ICAM-1 is important in initial endothelial capture of PMNs, whereas Mac-1 to ICAM-1 binding resists shear forces to stabilize the PMN-endothelium adhesion. Similar results have been published (10, 11) for fluid shear effect on the interactions between PMNs and ICAM-1-expressing colon carcinomas.
Protein secretion plays an important role in tumor cell and neutrophil biology. Although several proinflammatory cytokines and chemokines have been implicated in influencing adhesive properties of transformed cells, interleukin-8 (IL-8) is of particular interest because it promotes the growth of some tumors. Tumor cells that secrete high levels of IL-8 have been characterized as having an increased metastatic potential (18, 27). IL-8 is important in recruiting and activating PMNs (20) and binds to the CXCR1 and CXCR2 receptors. CXCR1 has not been detected in large quantities on melanoma cells (13), but tumor-secreted IL-8 can act on PMNs and influence their adhesion molecule expression.
The objective of this study is to understand the role of hydrodynamic forces and specifically the 2-integrin/ICAM-1 adhesion mechanism in PMN-mediated melanoma migration under shear conditions. We conclude that shear rate, rather than shear stress, plays a more significant role in PMN-melanoma aggregation and adhesion to the endothelium (Fig. 1). In addition, IL-8 is identified as an important chemokine, which is produced as a result of PMN-melanoma contact and facilitates melanoma-PMN-endothelium adhesion and subsequent melanoma extravasation.
|
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Fibroblast L-cells that had been transfected to express human ICAM-1 and E-selectin (EI cells; provided by Dr. Scott Simon, University of California, Davis) were maintained in culture as described elsewhere (7). E-Selectin and ICAM-1 levels were periodically checked by flow cytometry to verify expression level. ICAM-1 levels on EI cells were shown to be comparable with IL-1-stimulated human umbilical vein endothelial cells (7), and were used as a substrate for cell adhesion and as a model endothelium in this study. For particular assays, the EI monolayer was treated with blocking E-selectin or ICAM-1 antibodies (5 µg Ab per monolayer; CalTag Laboratories).
PMN isolation and preparation. Fresh blood was obtained from healthy adults under informed consent following a protocol approved by the Pennsylvania State University Institutional Review Board. Histopaque gradient (Sigma, St. Louis, MO) was used to isolate and enrich the PMN population. The isolated PMN layer was first suspended in 0.1% human serum albumin (Sigma) in Dulbeccos phosphate-buffered saline (DPBS) and washed. ACK lysis buffer (0.15 M NH4Cl, 10.0 mM KHCO3, 0.1 mM Na2EDTA in distilled H2O) was used to remove erythrocytes. The cells were washed with 0.1% human serum albumin/DPBS, resuspended at a concentration of 1 x 106 cells/ml, and rocked at 4°C until they were used, no longer than 4 h. To activate LFA-1 or Mac-1 on PMNs, cells were treated with phorbol 12-myristate 13-acetate (PMA, Sigma; 100 ng/ml, 20 min) or IL-8 (R&D Systems, Minneapolis, MN; 1 ng/ml, 1 h), respectively. PMA was not found to affect Mac-1 expression on PMNs (data not shown). In blocking assays, PMNs were treated with saturating concentrations of antibodies, 5 µg of IgG anti-human LFA-1 or Mac-1 (CalTag Laboratories) per 1 x 106 cells in blocking buffer (5% calf serum, 2% goat serum in DPBS) for 30 min at 4°C. Similarly, to block IL-8 receptors, PMNs were treated with mouse anti-human CXCR1 and CXCR2 antibodies (R&D Systems) with 6 and 10 µg/ml, respectively, in blocking buffer for 30 min at 4°C.
Dextran-supplemented medium. RPMI 1640 medium with 25 mM HEPES (Biosource, Camarillo, CA) was supplemented with 0.1% bovine serum albumin (BSA) and 14% ultra-high molecular weight dextran (2 x 106 MW; Sigma). A range of dextran-supplemented media were made to achieve a range of viscosities from 0.7 cP (no dextran) to 7.0 cP (4% dextran).
Flow migration assay.
The in vitro flow migration device is a recently developed, modified 48-well chemotactic Boyden chamber (Fig. 2) (6, 19). In brief, the top and bottom plates of the polycarbonate chamber are separated by a 0.02-in.-thick silicon gasket (PharmElast, SF Medical, Hudson, MA). A 7 cm x 2 cm opening cut from the center of the gasket forms the flow field. The wall shear stress (w) is related to the volumetric flow rate (Q) by
w = 6 µQ/wh2, where µ is the fluid viscosity, h is height, and w is width of the flow field.
|
Statistical significance between cases tested in the flow-migration chamber was determined by P values from an unpaired t-test, where P < 0.05 was considered significant (Sigma Plot; version 8). All error bars on flow migration data represent means ± SE.
Parallel plate flow assay. Adhesion and tethering experiments were performed in a parallel-plate flow chamber (Glycotech, Gaithersburg, MD) mounted on an inverted optical microscope with a x10 phase-contrast objective lens (Diaphot 330, Nikon, Toyko, Japan). The medium was perfused through the chamber using a syringe pump (Harvard Apparatus, Holliston, MA) to create a uniform laminar flow field in the chamber. A confluent EI-cell monolayer (35 mm petri dishes; Corning, Acton, MA) was used as the ligand-binding substrate on the bottom plate of the parallel plate chamber. The experiments were recorded using a video camera (model CCD72, MTI-Dage, Michigan City, IN) and video recorder (model AG-3200, Panasonic, Secaucus, NJ) equipped with a time-date generator (model VTG-33, FOR.A, Tokyo, Japan). The field of view was 800 µm long (direction of flow) by 600 µm wide. The EI monolayer was preinfused with warmed medium with the experimental viscosity (13.2 cP) for 45 min at a shear rate of 40 s1 before the introduction of the two cell suspensions. PMNs were either activated by IL-8 or treated with blocking antibodies (as described above). Both PMNs and C8161 cells were resuspended in appropriate dextran-supplemented medium. To allow the cell suspensions to reach the field of view on the EI monolayer, 1 x 106/ml PMNs and 1 x 106/ml C8161 were perfused at a low shear stress (0.10.3 dyn/cm2) for 120 s (accumulation phase). The flow rate was then increased to the experimental shear rate (55.5 s1), and kept constant for 68 min (shear application phase). Experiments were performed in triplicate. Statistical significance was tested by one-way ANOVA, where P > 0.05 was determined to be significant (Minitab version 14).
PMN tethering frequencies. The experimentally determined tethering frequency was the number of PMNs that adhered to the EI monolayer per unit time and area, including both rolling and firmly arrested cells. This frequency was normalized by cell flux to the surface to compensate for the different concentration of cells passing the same area of substrate at different shear rates. At higher shear rates, a higher concentration of cells would pass the endothelium and have the opportunity to adhere. This normalization followed the procedure cited in Rinker et al.'s (16) work based on equations from Munn et al. (14).
PMN-C8161 aggregation and adhesion efficiency analysis. Aggregation and adhesion of accumulated cells was counted manually from the video recording of the shear application phase of the assay. Values that were quantified include the number of collisions between entering C8161s and rolling and firmly arrested PMNs on the EI monolayer, and the number of PMN-C8161 aggregates firmly arrested on the EI monolayer as a result of a collision.
Adhesion efficiency was calculated by dividing the number of C8161 cells arrested on the EI monolayer by the number of C8161-PMN collisions. Arrested C8161 cells were quantified at the end of each assay as a result of accumulative collisions between entering C8161 cells and tethered PMNs. C8161-PMN collisions were those that occurred near the EI monolayer surface during the flow assay.
Co-culture of PMNs and C8161 cells. C8161 cells were cultured in 6-well plates (Corning). PMNs (5 x 106 per well), untreated or treated with anti-CXCR1 and CXCR2 antibodies (as described above), were added to each well either directly onto the C8161 monolayer or into a Transwell insert (0.4 µm pore; Corning) above the monolayer. As a control, PMNs were concurrently cultured in plates without C8161 cells. The plates were then incubated for 4 h at 37°C and 5% CO2. After 4 h, the PMNs were collected and fluorescently labeled for flow cytometry analysis (see description below).
Flow cytometry. The cells of interest were treated with murine anti-human CD marker primary antibodies (e.g., anti-LFA-1, anti-Mac-1, or anti-ICAM-1; 1 µg Ab/106 cells) (CalTag Laboratories) for 30 min at 4°C. The cells were then treated with secondary antibody, FITC-conjugated goat anti-mouse IgG F(ab)2 fragment (1 µg/106 cells) (Jackson ImmunoResearch, West Grove, PA) for 25 min at 4°C. In the case of blocking CXCR1 and CXCR2 receptors on PMNs, PE-conjugated anti-Mac-1 (1 µl/106 cells; CalTag Laboratories) was used to avoid binding secondary antibody to the existing CXCR1 and CXCR2 antibodies. The samples were fixed with 2% formaldehyde (Sigma) and analyzed with a flow cytometer (EPICS XL, Coulter, Fullerton, CA). Control cases used to determine background fluorescence were samples treated with secondary antibody only or PE-conjugated isotype control (CalTag Laboratories).
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
Population ratio of C8161s to PMNs affects melanoma extravasation. The ratio of C8161 cells to PMNs was examined to determine whether changing the relative concentrations would change the probability of a tumor cell colliding with and binding to a PMN. Both inactivated and IL-8-stimulated PMNs were used in flow-migration experiments. Figure 5 shows that doubling the number of PMNs resulted in a greater number of C8161 migration. In the presence of unstimulated PMNs, C8161 migration increased by 92% when the concentration ratio was changed to 1:2 (C8161:PMN), whereas migration increased by 32% when the number of IL-8 activated PMNs was increased. Control results show that the use of a 1:2 ratio of C8161 cells to fixed PMNs did not alter C8161 cell extravasation level (Fig. 5), suggesting PMN-mediated melanoma cell migration is adhesion specific, not solely influenced by the total number of cells in the shear flow.
|
|
|
Distinct role of LFA-1 and Mac-1 in PMN-melanoma aggregation under flow conditions.
The 2-integrin molecules, Mac-1 and LFA-1, appear to have different roles in PMN-facilitated melanoma extravasation. To understand this phenomenon better, it is useful to look at the requisite adhesion step before extravasation. With the use of a parallel plate chamber to characterize aggregate adhesion over the course of 5 min, the distinct roles of LFA-1 and Mac-1 in melanoma extravasation can be better understood. The rate of aggregation of C8161 to accumulated PMNs on the EI monolayer at a shear rate of 55.5 s1 was not significantly altered by blocking Mac-1, and LFA-1 alone supported adhesion up to the peak level observed for the untreated control at 3 min (Fig. 8). However, after 3 min, disaggregation from the EI monolayer proceeded more rapidly in the presence of anti-Mac-1 than in the untreated control. In comparison, Mac-1-dependent adhesion (in the presence of anti-LFA-1) proceeded more slowly and only reached a maximum level
50% lower than the control. These aggregates remained stably adhered to the surface of the EI monolayer over 5 min (Fig. 8). Furthermore, upregulating Mac-1 on PMNs by IL-8 treatment did not significantly change aggregation compared with the unstimulated case. The same result was found for adhesion of C8161 to accumulated PMN on an EI monolayer at other shear rates (data not shown). These data suggest that LFA-1 alone is sufficient for the initial escalation in PMN-C8161 aggregate formation and adhesion to the EI monolayer, whereas the contribution of Mac-1 is necessary to maintain the stability of those formed aggregates in a shear flow.
|
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Hydrodynamic forces play an important role in regulating melanoma cell adhesion and migration under a shear flow. Without the ability to bind to the endothelial surface alone under shear conditions, melanoma cells may recruit PMNs to aid in binding to the blood vessel wall. Determining how shear stress and shear rate effect this intercellular communication and interaction can increase the understanding of how fluid shear impacts melanoma extravasation in the microcirculation. With the use of dextran-supplemented medium to change viscosity, the shear stress was varied while holding shear rate constant or the shear rate was varied while holding shear stress constant. Melanoma cell migration was not significantly changed when shear stress was varied from 0.418 dyn/cm2 under a constant shear rate, but decreased significantly when the shear rate was increased 10-fold under a constant shear stress.
When the tethering, adhesion and migration stages of PMN-facilitated melanoma migration are analyzed, it becomes evident that there are two distinct stages of adhesion in PMN-facilitated melanoma adhesion and migration: PMN-endothelium adhesion and PMN-melanoma adhesion (Fig. 1). Each stage responds to the hydrodynamic environment differently. PMN tethering to the endothelial monolayer is both shear rate and shear stress dependent. In this experimental setup, this phase is mediated by SLex-E-Selectin adhesion and 2-integrin-ICAM-1 interactions. Adhesion of melanoma cells to PMN and subsequent migration are shear rate dependent and dominated by
2-integrin-ICAM-1 interactions. Because migration follows adhesion, this result appears to identify the adhesion stage as the determining factor for the efficiency of the melanoma migration.
The difference between the C8161 migration and the PMN tethering results under hydrodynamic forces supports the theory that PMNs facilitate C8161 migration. If C8161 cells used the traditional extravasation mechanism of binding to the endothelium itself, the response to shear would have been expected to be similar to that seen in single cell tethering (Fig. 4A). Because this is not the case, the results indicate two separate bonds are necessary for C8161 migration (Fig. 1) and the interesting shear rate dependence becomes apparent. The migration experiments examine adhesion of tumor cells to PMNs after PMNs have already adhered to the endothelium, whereas the tethering results more specifically focus on PMN to endothelium adhesion (Fig. 4A). The migration data show tumor cell-to-PMN adhesion is shear rate dependent and parallel plate flow chamber data of PMN-to-tumor cell aggregation show a similar trend (unpublished data). In contrast, the PMN-endothelium tethering is both shear rate and shear stress dependent, which is in agreement with previously published results on monocyte tethering on human umbilical vein endothelial cells (16).
PMN tethering interactions, mediated by selectins, are a prerequisite for subsequent adherence, mediated by 2 integrins on PMNs binding to ICAM-1 on the endothelium. Shear rate is inversely proportional to intercellular contact time (16). By decreasing shear rate, PMNs are in contact with the endothelium longer, which allows firm binding to occur. The same mechanism may be at play between PMNs and C8161 cells; a lower shear rate may increase the time the cells are in contact, therefore allowing more heterotypic binding and consequently more migration.
Rinker et al. (16) proposed when shear stress increases at a constant shear rate (and contact duration) after an initial tether is formed, the cell and its microvilli deform more, which allows more bonds to form and leads to a higher tethering frequency. This hypothesis agrees with Cao et al.'s (4) work. The PMN tethering data reported here follows the same shear stress dependence trend, signifying the importance of PMN deformation in binding between PMNs and the endothelium. However, PMN adhesion to the endothelium is necessary but not sufficient for PMN-facilitated melanoma cell adhesion or migration. Because migration data do not follow the same trend, this indicates that contact duration is more influential on C8161 migration than cell deformation.
One indication of the characteristics of the fluid flow in the migration and parallel plate flow chamber experiments is the Reynolds number. The Reynolds number local to the cell is defined as the ratio between inertia effects and viscous effects on the cell; Re = 2R/µ, where
is the media density,
is the shear rate, R is the radius of the cell, and µ is medium viscosity. When the shear rate and viscosity are changed in these experiments, this ratio is altered, which may play a role in the interactions between the cells and effect the resulting adhesion and migration. Analysis of both Rinker's and the cell tethering data reported here (Fig. 4A) reveals a correlation to the local cell Reynolds number (not shown). In contrast, a correlation between migration data and Reynolds number is not clear. Because the Reynolds number alone is not sufficient to explain the shear rate-dependent migration phenomena, additional flow characteristics and multibody dynamics are currently under investigation to determine a new correlation.
To minimize any possible shielding effects of dextran, ultra-high molecular weight dextran was used. Changes in osmolarity were found to be negligible and dextran was not found to affect adhesion molecule expression levels on any of the cell types used in this study, including melanoma cells, PMNs, or EI cells. Previously, shielding effects have been reported with 40,000 MW dextran (3); however, Rinker et al. (16) reported that the 2 x 106 molecular weight dextran did not shield monocyte rolling on the endothelium. Therefore, high molecular weight dextran was chosen to supplement the cell suspension used in this study.
Varying the PMN population with respect to the number of tumor cells lends some insight into the mechanics of PMN-facilitated tumor migration. Migration increased when the ratio of PMNs to C8161 cells was increased for both unstimulated and IL-8-treated PMN cases. By increasing the relative concentration of PMNs, the probability of PMNs and C8161 cells aggregating increased. Interestingly, doubling the concentration of PMNs increased migration in greater proportion when unstimulated PMNs were added than when IL-8-stimulated PMNs were used. This suggests both activating PMNs and increasing the number of PMNs increase C8161 migration, but the effects are not additive. Therefore, a maximum level of PMN facilitation of tumor cell migration may exist.
Comparing the number of adhered melanoma cells in the flow migration assay with cells that eventually migrate helps to characterize the transition between cell adhesion and cell migration. The number of adherent melanoma cells at 1 h compared with the number at 2 h shows melanoma migration progression, not disassociation. Disaggregation cannot be the cause of the difference between the number of adhered cells at 1 and 2 h due to the number of migrated cells after 4 h. The ratio of the number of adhered melanoma cells after 1 h to the number of migrated cells after 4 h, which is >0.9 or 90% for each case, indicates that nearly all adhered melanoma cells eventually migrate without apparent changes due to hydrodynamic conditions. This again supports that adhesion is the determining factor in melanoma migration. The number of melanoma cells that adhere is a direct representation of the number of melanoma cells that will migrate.
LFA-1 and Mac-1, the 2-integrins, have sequential roles in binding leukocytes to ICAM-1; adhesion begins with LFA-1-dependent capture and is stabilized and maintained by Mac-1 (8, 15). The experiments using the flow migration and parallel plate chambers allow the roles of LFA-1 and Mac-1 in PMN-melanoma cell aggregation and subsequent PMN-facilitated melanoma adhesion to the endothelium within a prescribed shear field to be elucidated. Upregulating or downregulating LFA-1 or Mac-1 showed a significant impact on the melanoma cell migration and adhesion results. Blocking LFA-1 inhibited PMN-facilitated melanoma migration through the endothelium; however, blocking Mac-1 had more of an effect. In the adhesion assays, LFA-1 affects adhesion over the entire time course, whereas the effect of Mac-1 is seen after only 3 min. This difference is apparent because of the longer time necessary for migration to occur than adhesion. This suggests that the stabilized adhesion provided by Mac-1 to ICAM-1 is more of a factor in successful C8161 migration under shear, but Mac-1 and LFA-1 are both necessary and neither is sufficient to allow PMNs to bind to C8161 cells and the endothelium.
Jadhav and Konstantopoulos (11) have shown that ICAM-1-expressing colon carcinoma cells bind to PMN under shear as a function of both contact duration and shear stress whereas sLex-expressing carcinoma cells (LS174T) bind to PMN as a function of only contact duration. Their experimental setup was a cone and plate viscometer, where two cell types (PMN and tumor) were allowed to collide and aggregate under a shear in a free suspension. In contrast, the data presented here is from a three-cell system (Fig. 1; PMN, tumor, and endothelial) where two separate binding events must occur near a planar surface. Jadhav and Konstantopoulos' results provided excellent insight into the kinetics of PMN-tumor cell aggregation, but might not be expected to explain PMN-tumor aggregation-mediated melanoma cell migration results presented here due to the necessary binding of PMNs on the endothelium in addition to PMN-melanoma aggregation.
PMN-facilitated melanoma adhesion to the endothelium is a multistep process, as shown in Fig. 1. Blocking either ICAM-1 or E-selectin adhesion molecules on the endothelial monolayer reduced C8161 migration, which suggests PMNs must bind to the endothelium before melanoma cells can bind to them. Blocking the ICAM-1 molecules on tumor cells also inhibited C8161 migration, which further indicates a 2-integrin/ICAM-1 binding mechanism is involved in PMN-facilitated melanoma cell adhesion and migration.
The level of interaction between PMNs and tumor cells has been shown to increase in the presence of inflammatory mediators such as IL-8 and TNF- (19). Results from Slattery and Dong (19) have shown that IL-8 is secreted by PMNs after interaction with C8161 tumor cells. To examine the role that endogenously produced IL-8 has on PMN-mediated melanoma cell extravasation, the IL-8 receptors CXCR1 and CXCR2 on PMNs were blocked. The use of these blocked PMNs inhibited migration of C8161 cells compared with the use of untreated PMNs. The dramatic inhibition of Mac-1 expression on CXCR1/2 blocked PMNs clearly identifies the role of melanoma-induced IL-8 production in PMN-facilitated tumor cell migration. In addition, while physical contact between C8161 cells and PMNs produces a slightly higher Mac-1 response, contact is clearly not requisite to stimulate a significant increase in Mac-1 expression. This suggests that a soluble factor, possibly the autocrine effect of PMN-secreted IL-8 (19), is responsible for this increase in Mac-1 expression.
PMN-facilitated melanoma transendothelial migration is a series of complex cellular and molecular interactions that are effected by the fluid dynamics of the surrounding flow. This study shows two separate bonds are necessary for PMN-melanoma-endothelium adhesion. Each step is both receptor and hydrodynamics dependent. The efficiency and strength of each receptor-ligand interaction is influenced by the surrounding hydrodynamic conditions. We have found the dominant and determining step, melanoma-PMN adhesion, to be shear rate dependent. Aggregation of melanoma cells with PMNs and subsequent migration require both a collision and bond formation between a melanoma cell and a tethered PMN. The success of this process is dominated by the time the two cell types are in contact and depends less on the cell deformation. The PMN-melanoma bond, which is influenced in a shear rate-dependent manner, is regulated by 2-integrin adhesion to ICAM-1, whereas the PMN-endothelial cell bond requires both E-selectin and ICAM-1 influenced by shear stress and cell deformability. Finally, endogenously produced IL-8 does contribute to PMN-facilitated melanoma migration through the CXCR1 and CXCR2 receptors.
![]() |
GRANTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
FOOTNOTES |
---|
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2. Aznavoorian S, Stracke ML, Krutzsch HC, Schiffmann E, and Liotta LA. Signal transduction for chemotaxis and haptotaxis by matrix molecules in tumor cells. J Cell Biol 110: 14271438, 1990.[Abstract]
3. Baldwin AL, Wu NZ, and Stein DL. Endothelial surface charge of intestinal mucosal capillaries and its modulation by dextran. Microvasc Res 42: 160178, 1991.[CrossRef][ISI][Medline]
4. Cao J, Donell B, Deaver DR, Lawrence MB, and Dong C. In vitro side-view technique and analysis of human T-leukemic cell adhesion to ICAM-1 in shear flow. Microvasc Res 55: 124137, 1998.[CrossRef][ISI][Medline]
5. Chambers AF, MacDonald IC, Schmidt EE, Morris VL, and Groom AC. Clinical targets for anti-metastasis therapy. Adv Cancer Res 79: 91121, 2000.[ISI][Medline]
6. Dong C, Slattery MJ, Rank BM, and Yun J. In vitro characterization and micromechanics of tumor cell chemotactic protrusion, locomotion, and extravasation. Ann Biomed Eng 30: 344355, 2002.[CrossRef][ISI][Medline]
7. Gopalan PK, Smith CW, Lu H, Berg E, Mcintire LV, and Simon SI. PMN CD18-dependent arrest on ICAM-1 in shear flow can be activated through L-selectin. J Immunol 158: 367375, 1997.[Abstract]
8. Hentzen ER, Neelamegham S, Kansas GS, Benanti JA, McIntire LV, Smith CW, and Simon SI. Sequential binding of CD11a/CD18 and CD11b/CD18 defines neutrophil capture and stable adhesion to intercellular adhesion molecule-1. Blood 95: 911920, 2000.
9. Hodgson L and Dong C. [Ca2+]i as a potential down-regulator of 2
1-integrin mediated A2058 tumor cell migration to type IV collagen. Am J Physiol Cell Physiol 281: C106C113, 2001.
10. Jadhav S, Bochner BS, and Konstantopoulos K. Hydrodynamic shear regulates the kinetics and receptor specificity of polymorphonuclear leukocyte-colon carcinoma cell adhesive interactions. J Immunol 167: 59865993, 2001.
11. Jadhav S and Konstantopoulos K. Fluid shear-and time-dependent modulation of molecular interactions between PMNs and colon carcinomas. Am J Physiol Cell Physiol 283: C1133C1143, 2002.
12. Liotta LA. Cancer cell invasion and metastasis. Sci Am 266: 5463, 1992.[ISI][Medline]
13. Müller A, Homey B, Soto H, Ge N, Catron D, Buchanan ME, McClanahan T, Murphy E, Yuan W, Wagner SN, Barrera JL, Mohar A, Verastegui E, and Zlotnik A. Involvement of chemokine receptors in breast cancer metastasis. Nature 410: 5056, 2001.[CrossRef][ISI][Medline]
14. Munn LL, Melder RJ, and Jain RK. Analysis of cell flux in the parallel plate flow chamber: implications for cell capture studies. Biophys J 67: 889895, 1994.[Abstract]
15. Neelamegham S, Taylor AD, Burns AR, Smith CW, and Simon SI. Hydrodynamic shear shows distinct roles for LFA-1 and MAC-1 in neutrophil adhesion to intercellular adhesion molecule-1. Blood 92: 16261638, 1998.
16. Rinker KD, Prabhakar V, and Truskey GA. Effect of contact time and force on monocyte adhesion to vascular endothelium. Biophys J 80: 17221732, 2001.
17. Scherbarth S and Orr FW. Intravital video microscopic evidence for regulation of metastasis by the hepatic microvasculature: effects of interleukin-1 on metastasis and the location of B16F1 melanoma cell arrest. Cancer Res 57: 41054110, 1997.[Abstract]
18. Singh RK, Varney ML, Bucana CD, and Johansson SL. Expression of interleukin-8 in primary and metastatic malignant melanoma of the skin. Melanoma Res 9: 383387, 1999.[ISI][Medline]
19. Slattery MJ and Dong C. Neutrophils influence melanoma adhesion and migration under flow conditions. Int J Cancer 106: 713722, 2003.[CrossRef][ISI][Medline]
20. Smith WB, Gamble JR, Clark-Lewis I, and Vadas MA. Interleukin-8 induces neutrophil transendothelial migration. Immunology 72: 6572, 1991.[ISI][Medline]
21. Starkey JR, Liggitt HD, Jones W, and Hosick HL. Influence of migratory blood cells on the attachment of tumor cells to vascular endothelium. Int J Cancer 34: 535543, 1984.[ISI][Medline]
22. Thorlacius H, Pricto J, Raud J, Gautam N, Patarroyuo M, Hedqvist P, and Lindbom L. Tumor cell arrest in the microcirculation: lack of evidence for a leukocyte-like rolling adhesive interaction with vascular endothelium in vivo. Clin Immunol Immunopathol 83: 6876, 1997.[CrossRef][ISI][Medline]
23. Welch DR, Schissel DJ, Howrey RP, and Aeed PA. Tumor-elicited polymorphonuclear cells, in contrast to "normal" circulating polymorphonuclear cells, stimulate invasive and metastatic potentials of rat mammary adenocarcinoma cells. Proc Natl Acad Sci USA 86: 58595863, 1989.[Abstract]
24. Welch DR, Bisi JE, Miller BE, Conaway D, Seftor EA, Yohem KH, Gilmore LB, Seftor REB, Nakajima M, and Hendrix MJC. Characterization of a highly invasive and spontaneously metastatic human malignant melanoma cell line. Int J Cancer 47: 227237, 1991.[ISI][Medline]
25. Wu QD, Wang JH, Condron C, Bouchier-Hayer D, and Redmond HP. Human neutrophils facilitate tumor cell transendothelial migration. Am J Physiol Cell Physiol 280: C814C822, 2001.
26. You J, Mastro AM, and Dong C. Application of the dual-micropipet technique to the measurement of tumor cell locomotion. Exp Cell Res 248: 160171, 1999.[CrossRef][ISI][Medline]
27. Zachariae COC, Thestrup-Pedersen K, and Matsushima K. Expression and secretion of leukocyte chemotactic cytokines by normal human melanocytes and melanoma cells. J Invest Dermatol 97: 593599, 1991.[CrossRef][ISI][Medline]
28. Zetter BR. Adhesion molecules in tumor metastasis. Semin Cancer Biol 4: 219229, 1993.[ISI][Medline]
|
HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Visit Other APS Journals Online |