Phase-II metabolism limits the antiproliferative activity of urolithins in human colon cancer cells.
OBJECTIVE
Urolithins, gut microbiota metabolites derived from ellagic acid and ellagitannins, reach micromolar concentrations in the colon lumen where can have anti-inflammatory and anticancer effects. The antiproliferative activity of urolithins (Uro-A, Uro-B, Uro-C and Uro-D) and their most relevant in vivo glucuronides were evaluated in three human colon cancer cell lines (Caco-2, SW480 and HT-29).


METHODS
Cell proliferation was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and Trypan blue exclusion assays. Cell cycle was evaluated by flow cytometry and urolithins metabolism by HPLC–MS/MS.


RESULTS
Urolithins inhibited cell proliferation and cell cycle progression in a time- and dose-dependent manner and arrested the cells at S and G2/M phases, depending on the urolithin. Uro-A exerted the highest antiproliferative activity, followed by Uro-C, Uro-D and Uro-B. Unlike Caco-2 and SW480 cells, HT-29 cells partially overcame the effects after 48 h, which was related to the complete glucuronidation of urolithins. Uro-A or Uro-B glucuronides did not affect cell cycle and showed lower antiproliferative activity than their aglycone counterparts. Uro-A or Uro-B plus inhibitors of drug efflux ABC transporters partially prevented the glucuronidation of urolithins in HT-29 cells which became more sensitive.


CONCLUSIONS
Uro-A, Uro-B, Uro-C and Uro-D exerted different antiproliferative effects depending on the colon cancer cell line. We also report here, for the first time, the role of ABC transporters and Phase-II metabolism in HT-29 cells as a mechanism of cancer resistance against urolithins due to their conversion to glucuronide conjugates that exerted lower antiproliferative activity.
Antonio
A
González-Sarrías
Juan Antonio
JA
Giménez-Bastida
María Ángeles
MÁ
Núñez-Sánchez
Mar
M
Larrosa
María Teresa
MT
García-Conesa
Francisco A
FA
Tomás-Barberán
Juan Carlos
JC
Espín
D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000378:metabolism; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003106:Colon / Q000187:drug effects / Q000378:metabolism; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D003374:Coumarins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D020719:Glucuronides / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D047348:Hydrolyzable Tannins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D049990:Membrane Transport Modulators / Q000494:pharmacology; D050217:Metabolic Detoxication, Phase II; D016196:S Phase / Q000187:drug effects
D018528:ATP-Binding Cassette Transporters; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000903:Antibiotics, Antineoplastic; D003374:Coumarins; D020719:Glucuronides; D047348:Hydrolyzable Tannins; D049990:Membrane Transport Modulators; C000595064:urolithin B; C588364:urolithin C; C000595063:urolithin D; C026423:3,8-dihydroxy-6H-dibenzo(b,d)pyran-6-one