These features could be compared to the in vivo situation where the ability of tumour cells to detach from the primary tumour, invade through the ECM, survive in the blood stream, and invade and form tumours at

secondary sites, leads to the formation of metastases. Therefore, we believe that Clone #3 represents an in vitro model of tumour cells with increased metastatic potential. In contrast Clone #8 appears to be a model of tumour cells with decreased metastatic potential, showing decreased invasion, increased adhesion, increased sensitivity to anoikis and BI-2536 reduced ability to grow and form colonies in anchorage-independent conditions. Integrins are involved in regulating growth, differentiation, and death by regulating the interaction between cell and ECM [7]. In pancreatic cancer, links have previously been established between increased invasion and decreased adhesion to ECM proteins in vitro and to high metastatic potential in vivo [27–29]. In general, the loss or gain of expression of individual integrins appears to be indirectly EX 527 chemical structure see more associated with malignant transformation and involved in tumour progression and metastasis.

Over expression of α5β1 in CHO cells demonstrated reduced malignancy [30], whereas α2β1 and α3β1 were expressed in non-neoplastic and fibroadenomas but were low or absent in highly invasive mammary carcinomas [31]. In our study, Clone #3 showed reduced expression of integrins β1, α5 and α6 compared to Clone #8, which correlates with the reduced adhesion to laminin and fibronectin, as integrin α5β1 is a receptor for fibronectin and α6β1 is a receptor for laminin [32, 26]. Integrin β1, α5 and α6 siRNA transfection in Clone #8 resulted in significantly increased motility and invasion through matrigel and fibronectin, and reduced adhesion to matrigel and fibronectin. Loss of integrin β1 did not alter ASK1 the invasion or adhesion of Clone #8 cells to laminin, but loss

of α6 significantly reduced adhesion to laminin. These results suggest that inhibition of integrin β1 alone is not sufficient to block adhesion to laminin. Other integrin complexes such as α6β4 [33] could control laminin-mediated adhesion/invasion in these cells. Gilcrease et al. [34] showed that α6β4 cross linking in suspended non adherent breast cancer cells resulted in cell surface clustering of EGFR, increasing EGFR-mediated activation of Rho in response to EGF, which may lead to tumour cell migration. Knockdown of the expression of integrin β1 in Clone #8 also revealed a more anoikis resistant phenotype. Disruption of β1 integrin complexes has previously implicated in induction of anoikis [35–37].