Recruitment of KRAS downstream target ARL4C to membrane protrusions accelerates pancreatic cancer cell invasion.

Pancreatic cancer (PC) has a high mortality rate due to metastasis. Whereas KRAS is mutated in most PC patients, controlling KRAS or its downstream effectors has not been succeeded clinically. ARL4C is a small G protein whose expression is induced by the Wnt and EGF-RAS pathways. In the present study, we found that ARL4C is frequently overexpressed in PC patients and showed that its unique localization to membrane protrusions is required for cancer cell invasion. IQGAP1 was identified as a novel interacting protein for ARL4C. ARL4C recruited IQGAP1 and its downstream effector, MMP14, to membrane protrusions. Specific localization of ARL4C, IQGAP1, and MMP14 was the active site of invasion, which induced degradation of the extracellular matrix. Moreover, subcutaneously injected antisense oligonucleotide (ASO) against ARL4C into tumor-bearing mice suppressed metastasis of PC. These results suggest that ARL4C-IQGAP1-MMP14 signaling is activated at membrane protrusions of PC cells.