Inhibitory effect of the sugarcane cystatin CaneCPI-4 on cathepsins B and L and human breast cancer cell invasion.
The lysosomal cysteine proteases cathepsin B and L play important roles in tumor cell invasion. An imbalance between these cathepsins and their endogenous inhibitors, the cystatins, has been associated with development of the metastatic phenotype. Accordingly, many studies have indicated potential use of cystatins in therapeutic approaches. We report a novel cystatin from sugarcane (Saccharum officinarum), CaneCPI-4, with strong inhibitory activity against cathepsins B (K(i) = 0.83 nM) and L (K(i) = 0.021 nM). The invasive ability of MDA-MB-231 human breast cancer cells expressing CaneCPI-4 was only slightly decreased. In contrast, addition of low, non-toxic concentrations of recombinant His-tagged CaneCPI-4 significantly reduced invasion through a Matrigel matrix. Immunoblot analyses failed to detect the recombinant protein inside cells, indicating that the cystatin was not internalized by endocytosis, but exerted its anti-invasive effect mainly through inhibition of extracellular cathepsins. Our findings open the possibility of considering phytocystatins for anti-cancer strategies.
Gianotti
Andréia
A
Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washington Luis km 235, 13565-905, São Carlos, SP, Brazil.
Sommer
César A
CA
Carmona
Adriana K
AK
Henrique-Silva
Flávio
F
D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D045744:Cell Line, Tumor; D015891:Cystatins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D031786:Saccharum / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D015891:Cystatins; D002403:Cathepsins; D002401:Cathepsin B