title: Enhanced antiproliferative and apoptotic response of HT-29 adenocarcinoma cells to combination of photoactivated hypericin and farnesyltransferase inhibitor manumycin A.
abstract: Several photodynamically-active substances and farnesyltransferase inhibitors are currently being investigated as promising anticancer drugs. In this study, the combined effect of hypericin (the photodynamically-active pigment from Hypericum perforatum) and selective farnesyltransferase inhibitor manumycin (manumycin A; the selective farnesyltransferase inhibitor from Streptomyces parvulus) on HT-29 adenocarcinoma cells was examined. We found that the combination treatment of cells with photoactivated hypericin and manumycin resulted in enhanced antiproliferative and apoptotic response compared to the effect of single treatments. This was associated with increased suppression of clonogenic growth, S phase cell cycle arrest, elevated caspase-3/7 activity and time-dependent total cleavage of procaspase-3 and lamin B, cleavage of p21Bax into p18Bax and massive PARP cleavage. Moreover, we found that the apoptosis-inducing factor is implicated in signaling events triggered by photoactivated hypericin. Our results showed the relocalization of apoptosis-inducing factor (AIF) to the nuclei after hypericin treatment. In addition, we discovered that not only manumycin but also photoactivated hypericin induced the reduction of total Ras protein level. Manumycin decreased the amount of farnesylated Ras, and the combination treatment decreased the amount of both farnesylated and non-farnesylated Ras protein more dramatically. The present findings indicate that the inhibition of Ras processing may be the determining factor for enhancing the antiproliferative and apoptotic effects of combination treatment on HT-29 cells.
authors.affiliation: Institute of Biology and Ecology, Faculty of Sciences, P. J. Šafárik University, Moyzesova 11, Košice 041 65, Slovakia. veronika.sackova@upjs.sk
authors.forename: Veronika
authors.initials: V
authors.lastname: Sačková
authors.forename: Lucia
authors.initials: L
authors.lastname: Kuliková
authors.forename: Martin
authors.initials: M
authors.lastname: Kello
authors.forename: Ivana
authors.initials: I
authors.lastname: Uhrinová
authors.forename: Peter
authors.initials: P
authors.lastname: Fedoročko
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism*; D000873:Anthracenes; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D053179:Caspase 7 / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019073:HT29 Cells; D006801:Humans; D034921:Lamin Type B / Q000235:genetics / Q000378:metabolism; D010569:Perylene / Q000031:analogs & derivatives* / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011090:Polyenes / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000873:Anthracenes; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D034921:Lamin Type B; D011090:Polyenes; D053284:Polyunsaturated Alkamides; D011838:Radiation-Sensitizing Agents; D051028:bcl-2-Associated X Protein; D010569:Perylene; C004965:hypericin; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D053179:Caspase 7; D018631:ras Proteins; C054474:manumycin