PI3K and beta1-integrin pathways play different roles in regulating 3D matrix-induced breast cancer cell invasion. Representative MDA-MB-231 trajectory tracks were attained as described in Methods. Orientation angles of the trajectories relative to the X-axis were rounded to the nearest 20th degree in order to identify a mode orientation angle. This mode was arbitrarily set as 0° and the original angles were rotated accordingly (see Methods for additional details). The resulting tracks were plotted as if all shared a common origin to generate a star like pattern. Graph scales are shown in micrometers to appreciate distances travelled during the recorded 6 h periods. Note that cells invading through tumor-associated 3D ECMs appear to move relatively fast (length of tacks), directional (straightness of tracks) and with a relative greater level of common or parallel orientation (orientation of tracks near the X-axis) when compared to control 3D ECMs. In addition, inhibition of beta1-integrin function (mAb13) effectively blocked cell invasion through control 3D ECMs, as shown by the resulting relatively small star. In contrast, blockage of beta1-integrin activity in these invasive cells triggered a change in the invasive strategy induced by tumor-associated 3D ECMs. This observation is apparent by contemplating the relatively large stars with wiggle tracks, as opposed to straight tracks, that lack organization near the X-axis in all experimental data attained in the presence of mAb13.
Castelló-Cros et al. BMC Cancer 2009 9:94 doi:10.1186/1471-2407-9-94