Bloqueio da integrina αvβ3 inibe apoptose e induz autofagia em células tumorais de cancêr de mama

Abstract

Integrins are key receptors that mediate cell adhesion to the extracellular matrix (ECM) and regulate cell behavior including cell migration. Particularly, αvβ3 integrin, the vitronectin receptor, plays a key role in both physiological angiogenesis and in tumor progression. This receptor recognizes the arginine-glycine-aspartic acid (RGD) motif in ECM proteins and it can be antagonized by RGD-peptides, resulting in decreased cell migration and invasion. RGD-based drugs have shown disappointing results in clinical trials; however, the reasons for their lack of activity are still obscure. Aiming to contribute to a better understanding on the molecular consequences of integrin inhibition, we have tested a recombinant RGD-disintegrin (DisBa-01) in two types of murine cell lines, breast tumor 4T1BM2 cells and L929 fibroblasts. Only tumor cells showed decreased motility and adhesion as well as morphologic alterations upon DisBa-01 treatment. This result was attributed to the higher levels of αvβ3 in 4T1BM2 cells making them more sensitive to DisBa-01 blocking. Flow cytometry analysis showed that DisBa-01 induced cell cycle arrest at S phase in 4T1BM2 cells, but did not induce apoptosis, which was consistent with the decrease in caspase-3, 8 and 9 expression at mRNA and protein levels. It was also observed that this disintegrin increases LC3B expression in both cell lines, an indicator of autophagic induction. In conclusion, DisBa-01 specificity towards 4T1BM2 cells when compared to L929, could be due to the higher level of expression of αv and β3 integrins in these cells, and these observations suggest new insights on the effects of RGD-based inhibitors considering their importance on drug development for human health.