A defect in cell-to-cell adhesion via integrin-fibronectin interactions in a highly metastatic tumor cell line

Evaluation of midkine and anterior gradient 2 in a multimarker panel for the detection of ovarian cancer

The aims of this study were: to characterise and compare plasma concentrations of midkine (MDK) in normal healthy women with concentrations observed in women with ovarian cancer; and to establish and compare the performance of MDK with that of anterior gradient 2 protein (AGR2) and CA125 in the development of multi-analyte classification algorithms for ovarian cancer. Median plasma concentrations of immunoreactive MDK, AGR2 and CA125 were significantly greater in the case cohort (909 pg/ml, 765 pg/ml and 502 U/ml, respectively n = 46) than in the control cohort (383 pg/ml, 188 pg/ml and 13 U/ml, respectively n = 61) (p < 0.001). The area under the receiver operator characteristic curve (AUC) for MDK and AGR2 was not significantly different (0.734 ± 0.046 and 0.784 ± 0.049, respectively, mean ± SE) but were both significantly less than the AUC for CA125 (0.934 ± 0.030, p < 0.003). When subjected to stochastic gradient boosted logistic regression modelling, the AUC of the multi-analyte panel (MDK, AGR2 and CA125, 0.988 ± 0.010) was significantly greater than that of CA125 alone (0.934 ± 0.030, p = 0.035). The sensitivity and specificity of the multi-analyte algorithm were 95.2 and 97.7%, respectively. Within the study cohort, CA125 displayed a sensitivity and specificity of 87.0 and 94.6%, respectively. The data obtained in this study confirm that both MDK and AGR2 individually display utility as biomarkers for ovarian cancer and that in a multi-analyte panel significantly improve the diagnostic utility of CA125 in symptomatic women.

Focal adhesion kinase expression is not a prognostic predictor in colon adenocarcinoma patients

AIM

Focal adhesion kinase (FAK) is an enzyme of the tyrosine kinase group linked to signaling pathways between cells and their extracellular matrix. FAK expression in tumor cells in vitro may correlate with their ability for invasion and metastasis.

METHODS

FAK protein expression was examined immunohistochemically in 80 cases of colon adenocarcinoma, and correlated with clinicopathological parameters; tumor proliferative capacity, reflected by Ki-67 antigen expression; and survival.

RESULTS

All tumor samples were FAK positive compared to normal colonic mucosa. FAK protein overexpression was seen in 32 out of 80 cases. FAK protein overexpression did not correlated with tumor histological grade, stage, Ki-67 positivity or survival.

CONCLUSIONS

Raised FAK protein expression was noted by immunohistochemistry in human colon carcinoma cases. The implication are discussed.

Beta 1-integrins regulate the formation and adhesion of ovarian carcinoma multicellular spheroids

Ovarian carcinoma multicellular spheroids are an in vitro model of micrometastasis whose adhesive abilities have not been elucidated. In this study, we identified adhesion molecules that mediate the formation of ovarian carcinoma spheroids and their subsequent adhesion to extracellular matrix proteins. The NIH:OVCAR5, but not the SKOV3, ovarian carcinoma cell line formed spheroids similar to multicellular aggregates isolated from patient ascitic fluid. NIH:OVCAR5 spheroid formation was augmented by a beta 1-integrin-stimulating monoclonal antibody or exogenous fibronectin, but was inhibited by blocking monoclonal antibodies against the alpha 5- or beta 1-integrin subunits. By immunohistochemical staining, alpha 2-, alpha 3-, alpha 5-, alpha 6-, and beta 1-integrin subunits, CD44, and fibronectin were detected in NIH:OVCAR5 spheroids. NIH:OVCAR5 spheroids adhered to fibronectin, laminin, and type IV collagen, and this adhesion was partially inhibited by blocking antibodies against the alpha 5-, alpha 6-, and alpha 2-integrin subunits, respectively. A blocking monoclonal antibody against the beta 1-integrin subunit completely inhibited adhesion of the spheroids to all three proteins. These results suggest that interactions between the alpha 5 beta 1-integrin and fibronectin mediate the formation of ovarian carcinoma spheroids and that their adhesion to extracellular matrix proteins at sites of secondary tumor growth may be mediated by a complex interaction between multiple integrins and their ligands.

Fibronectin is chemotactic for CT 26 colon carcinoma cells: sub-lines selected for increased chemotaxis to fibronectin display decreased tumorigenicity and lung colonization

CT 26 murine colon carcinoma cells demonstrated directional migration (chemotaxis) in response to fibronectin (FN). Sub-lines were derived by positive and negative selection to FN across Transwell filters of 8 microm pore size. The FL6 sub-line (positively selected) demonstrated a significantly increased chemotactic response (P<0.01) to FN compared with parental CT 26 cells, while the FU7 sub-line (negatively selected) showed a reduced chemotactic response to FN (P<0.01). Comparable levels of alpha4, alpha5, alphav and beta1 integrins, which mediate FN attachment, were expressed on positively and negatively selected sub-lines and parental CT 26 cells. Activation of integrins with Mn2+ suggested that the integrins expressed on FL6 cells were in the fully activated state; in contrast FU7 cells displayed only partially activated integrins. Cell attachment and integrin activation status of the sub-lines correlated with their chemotactic response to FN. In vivo FL6 cells showed a significantly reduced tumour growth rate s.c. and a reduction in the number of lung colonies formed following i.v. injection compared with parental CT 26 and FU7 cells. In contrast FU7 cells displayed a significant increase in s.c. tumour growth and the number of lung colonies when compared with the parental line and FL6 sub-line. The results indicate that interaction between integrin receptors expressed on cancer cells and FN plays a central role in the chemotactic response of CT 26 colon carcinoma cells, and that in this model cells selected for chemotaxis to FN displayed a reduced malignant potential.