Response of Aldehyde Dehydrogenase (ALDH) after Cisplatin and All-Trans Retinoic Acid (ATRA) treatment of Spheroid-derived Cells (SDCs) from cervical cancer cell lines
20 September 2018 (online)
Cancer stem cells (CSC) can be enriched by 3- dimensional culture techniques (Spheroids). ALDH is regarded a ubiquitous CSC marker. It contributes to cancer drug resistance due to its detoxificating property. ATRA is a downstream product of ALDH and is capable to induce CSC differentiation. We observed the impact of ATRA or/and cisplatin on ALDH expression in cervical cancer cell line-derived SDCs.
Materials and methods:
Cell lines, Hela, MRIH186, and SiHa were used to generate spheroids and subsequently treated with different concentrations of ATRA or/and cisplatin. ALDH expression was evaluated after 72h drug administration using ALDEFLUOR kit by flow cytometry. The mRNA expression of ALDH isotypes was detected by real time PCR.
Compared to the corresponding monolayer cells, the spheroid-derived cells showed higher ALDH+ cell frequency (5.12-, 1.89-, 1.85-fold up-regulated Hela, MRIH186, and SiHa, respectively; p < 0.05). Upon treatment with different concentrations of ATRA, the ALDH+ cell proportion showed a dose-dependent reduction in all cell lines. A bi-phasic response was found after cisplatin treatment. At concentrations below its IC50, cisplatin increased ALDH+ frequency (1.83-, 1.67-, 2.04-fold in Hela, MRIH186, and SiHa, respectively; p < 0.05). At higher cisplatin concentration ALDH+ cell frequency was sharply reduced. Combined treatment with ATRA and cisplatin resulted in an enhanced decline of ALDH expression. mRNA expression of ALDH1A1 and ALDH1A3 was reduced by ATRA.
ATRA can reduce ALDH+ cell frequency in cervical SDCs. The combination of ATRA with cytotoxic drugs might be a promising strategy to overcome the chemo-resistance caused by CSC.