Semaphorin 3F Responses To Neuropilin 2 Isoform Knockdowns In H157 Lung Cancer Cells

Semaphorin 3F is a well-known tumor suppressor that is able to inhibit tumor metastasis. Neuropilin 2 is its high affinity receptor, but it has two isoforms, “a” and “b”. SEMA3F is predicted to bind to the “a” isoform in order to function as a tumor suppressor, but it is unclear whether semaphorin 3F binds specifically to one isoform or the other to function as a tumor suppressor. Western Blots tested to see if isoform knockdowns in H157 lung cancer cells affected signaling associated with tumor metastasis. To test for SEMA3F effects on adhesion, we ran an adhesion assay to see how the cells attached to an ECM substrate. However, the adhesion that we observed could be static or dynamic, so we set up a pacman migration assay to assess the adhesive properties of the cells. The results gathered from each of these tests showed that SEMA3F utilizes both isoforms to function as a tumor suppressor. The “a” and “b” isoform knockdowns expressed metastatic signaling, transforming SEMA3F into a tumor promoter rather than an inhibitor. Therefore we can assess that semaphorin 3F needs both isoforms to function. A possible model for this is that a heterodimer between both of the isoforms is needed for SEMA3F to bind and send a tumor suppressing signal. It is also possible that a certain ration of NRP2a to NRP2b needs to be maintained in the cell for SEMA3F to function properly