Antitumor properties of aloe-emodin and induction of transglutaminase 2 activity in B16-F10 melanoma cells.
OBJECTIVE
Aloe-emodin (AE), a natural hydroxyanthraquinone compound, has been reported as a potential anticancer agent. We studied the antineoplastic properties of AE on highly metastatic B16-F10 melanoma murine cells.


METHODS
Cell proliferation was assessed by cell counting and viability was investigated using MTT and Trypan Bleu exclusion tests. As a growth marker, we determined intracellular polyamine levels by high performance liquid chromatography. Then, we evaluated transglutaminase 2 (TG2) activity, protoporphyrin IX accumulation and melanin content as differentiative markers. Tyrosinase activity was checked by DOPA-staining assay. The antimetastatic effect of AE was evaluated by means of a series of in vitro metastatic assays, including aggregation, wound healing migration, adhesion, 3D-invasion, circular invasion and the Boyden chamber invasion assays. Gelatin zymography was performed to evaluate metalloproteinase activities.


RESULTS
Our results demonstrated inhibitory effects of AE on melanoma cell proliferation and invasion power, accompanied by the stimulation of cell differentiation parameters. Cell differentiation correlated with a remarkable increase of the activity of the transamidating form of TG2, with a significative enhancement of cell adhesion and aggregation. Impaired invasion was paralleled by the decrease of the secretion of matrix metalloproteinase-9.


CONCLUSIONS
The overall data confirm a remarkable antiproliferative, antimetastatic and differentiative capability of this anthraquinone. Results suggest that AE appears particularly promising for its potential application in the newborn differentiation therapy of cancer.
Tabolacci
Claudio
C
Department of Biology, University Tor Vergata, Rome, Italy.
Lentini
Alessandro
A
Mattioli
Palma
P
Provenzano
Bruno
B
Oliverio
Serafina
S
Carlomosti
Fabrizio
F
Beninati
Simone
S
D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002449:Cell Aggregation / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004790:Enzyme Induction; D019204:GTP-Binding Proteins / Q000096:biosynthesis* / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008543:Melanins / Q000096:biosynthesis; D008546:Melanoma, Experimental / Q000201:enzymology / Q000473:pathology; D051379:Mice; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011524:Protoporphyrins / Q000378:metabolism; D011503:Transglutaminases / Q000096:biosynthesis* / Q000378:metabolism
D000880:Anthraquinones; D000972:Antineoplastic Agents, Phytogenic; D008543:Melanins; D011524:Protoporphyrins; C028025:protoporphyrin IX; C518327:aloe emodin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D020782:Matrix Metalloproteinases; D019204:GTP-Binding Proteins; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase