Inhibition of plexin-A4 expression in cancer cells inhibits their proliferation and the tumor forming ability of U87MG glioma cells. (A-B) U87MG or A549 cells were infected with lentiviruses directing expression of sh-control or sh-plexA4. The cells were then seeded at a concentration of 2 × 104 cells/well in 24-well dishes. The number of adherent cells in each well was determined after 3 days as described. The average of 3 independent experiments each of which was done in triplicates is shown. (C) MDA-MB-435 or A549 tumor cells were infected with an empty lentiviral expression vector or with lentiviruses directing expression of plexin-A4. The proliferation of the cells was then determined as described. The average ratio between cell density on days 3 and 0 of control cells determined in 3 independent experiments was designated as 100% and compared with the same ratio determined in silenced cells. Each column represents the average of 3 independent experiments. (D) The development of tumors derived from U87MG cells silenced for plexin-A4 expression (sh-plexA4) was compared with the development of tumors derived from control cells expressing a nontargeting shRNA (sh-control). (E) At the end of the experiment tumors were excised and weighed. Shown is a representative experiment. The experiment was repeated twice with similar results. (F) U87MG cells expressing a control shRNA (sh-control) or shRNAs targeting sema3A (sh-sema3A) or sema6B (sh-sema6B) were seeded in 24 well dishes and their proliferation examined as described in “Methods.” The average of 2 independent experiments each of which was done in triplicates is shown. (G) The development of tumors derived from U87MG cells silenced for sema-6B expression (sh-sema6B) was compared with the development of tumors derived from control cells expressing a nontargeting shRNA (sh-control). (H) At the end of the experiment tumors were excised and weighed.
