1p36.12

RAP1GA1,RAP1GAP1,RAP1GAPII,RAPGAP

Solid tumors

Papillary thyroid cancer, pancreatic cancer, prostate cancer, melanoma tumors

Rap1GAP, which acts as a GTPase activator for the nuclear Ras-related regulatory protein Rap1, was a specific negative regulator of Rap1, and the monomeric G protein Rap1 has been implicated in cancer tumorigenesis. It signals to pathways involved in cell adhesion, migration, and survival. Loss of Rap1GAP was discovered in papillary thyroid cancer, pancreatic cancer, prostate cancer, melanoma tumors, and their cell lines, all of them exhibited increased Rap1 activity, that activation of Rap1 promotes cell proliferation and migration potentiality through the mitogen-activated protein kinase pathway and integrin activation. As a putative tumor suppressor gene, Rap1GAP inhibits tumor growth but induces MMP2- and MMP9-mediated squamous cell carcinoma invasion and tumor progression, suggesting a role for this protein as a biomarker for early N-stage, aggressive squamous cell carcinomas.

Myelodysplastic syndrome (MDS)

The expression level of Rap1GAP in MDS patients significantly increased as compared with patients with non-malignant blood diseases or acute myeloid leukemia (AML). Among MDS patients, the expression level of Rap1GAP in MDS-refractory anemia (RA) was significantly higher than that in MDS-refractory anemia with excess of blasts (RAEB).
On the other hand, inhibiting Rap1 activity by expression of Rap1GAP increased leukocyte transendothelial migration, providing physiological relevance to the hypothesis that Rap1 augments barrier function of inter-endothelial cell junctions, implying the relevance of Rap1GAP in the regulation of haematogenesis.