HDAC2 and PCNA expression is correlated to decreasing of endoxifen sensitivity in human breast cancer stem cells ALDH+

Background: Breast cancer stem cells (BCSCs) are subpopulation of cancer cells that has the ability to generate new tumor and similar properties to stem cell. Our previous study using breast cancer patients revealed that gene expression of histone deacetylase 2 (HDAC2) and proliferating cell nuclear antigen (PCNA) were significantly altered after neoadjuvant hormone and chemotherapy. This study aimed to analyze the correlation between HDAC2 and PCNA expressions with the viability of breast cancer stem cells aldehyde dehydrogenase + (BCSC ALDH+) treated by endoxifen. Method: Samples are human primary BCSCs ALDH+ that treated with 4 uM of endoxifen for 2, 4, 6, 8, 10, 12, 14 days, respectively. Cell viability was measured using trypan blue exclusion assay and the mRNA expressions of HDAC2 and PCNA were determined using qRT-PCR. Results: The viability of BCSCs ALDH+ was decreased after 2 days until 4 days-endoxifen treatment. It also demonstrated that mRNA expression of HDAC2 and PCNA were decreased in this period. But after 8 daysendoxifen treatment, the viability of BCSCs ALDH+ was increased. The increasing of viability was higher in 14 days-endoxifen treatment. The mRNA expression of HDAC2 and PCNA also showed increasing begin on 8 days and continued to increase until 14-days endoxifen treatment. We found a similar pattern between HDAC2 and PCNA expression and cell viability Conclusion: Prolonge endoxifen treatment decrease sensitivity of endoxifen effect in human BCSC and the expression of HDAC2 and PCNA are correlated to human BCSCs viability after endoxifen treatment. (Health Science Journal of Indonesia 2019;10(2):77-81)