Here, we describe how the hyperactivation of Rac1 via the P29S mutation (Rac1<sup>P29S</sup>) in melanoma hijacks branched actin network assembly to coordinate proliferative cues that facilitate metastasis and drug resistance.
A point mutation (P29S) in the RAS-related C3 botulinum toxin substrate 1 (RAC1) was considered to be a trigger for melanoma, a form of skin cancer with highest mortality rate.
RAC1 is a GTPase member of the RAS superfamily, and RAC1(P29S) was recently identified as the third most common recurrent mutation in melanomas, affecting 4-7% of the patients.
Conversely, RNAi-mediated silencing of endogenous RAC1 P29S in a melanoma cell line with a co-occurring BRAF V600 mutation increased sensitivity to vemurafenib and dabrafenib.
Rac1 P29S mutant is known to strongly promote oncogenesis by facilitating its intrinsic GDP dissociation and thereby increasing the level of the GTP-bound state.
Children with IBD treated with thiopurines were prospectively followed for 1 year and were genotyped for 3 Rac1 SNPs previously found to be relevant to IBD: rs10951982, rs4720672, and rs34932801.
Here, we describe how the hyperactivation of Rac1 via the P29S mutation (Rac1<sup>P29S</sup>) in melanoma hijacks branched actin network assembly to coordinate proliferative cues that facilitate metastasis and drug resistance.
In multivariate logistic regression, <i>RAC1</i> rs10951982 (OR 6.15, 95% CI: 2.98 to 13.41; <i>p</i> < 0.001) remained significantly associated with increased risk of melanoma.
In silico modeling, mouse fibroblasts spreading assays, and in vivo overexpression assays using zebrafish as a surrogate model demonstrated that the p.Cys18Tyr and p.Asn39Ser RAC1 variants function as dominant-negative alleles and result in microcephaly, reduced neuronal proliferation, and cerebellar abnormalities in vivo.
Four individuals, each harboring one of c.53G>A (p.Cys18Tyr), c.116A>G (p.Asn39Ser), c.218C>T (p.Pro73Leu), and c.470G>A (p.Cys157Tyr) variants, were microcephalic, with head circumferences between -2.5 to -5 SD.
A point mutation (P29S) in the RAS-related C3 botulinum toxin substrate 1 (RAC1) was considered to be a trigger for melanoma, a form of skin cancer with highest mortality rate.