486PD - MicroRNA-125b functions as a key arbitrator for Mucin1 expressing breast cancer stem-like cells proliferation, migration and drug resistance

Date 21 December 2015
Event ESMO Asia 2015 Congress
Session Basic Science, biomarkers, new diagnostics and translational research
Topics Basic Science
Breast Cancer
Translational Research
Presenter MADHULIKA Singh
Citation Annals of Oncology (2015) 26 (suppl_9): 148-152. 10.1093/annonc/mdv533
Authors M. Singh1, S. Mishra2, Y. Shukla1
  • 1Proteomics Laboratory, CSIR-Indian Institute of Toxicology Research, 226001 - Lucknow/IN
  • 2Proteomics Laboratory, CSIR-IITR, 226001 - Lucknow/IN

Abstract

Aim/Background

Mucin 1 (Muc1) is a secreted, oncogenic mucin that is aberrantly overexpressed in breast cancer cells but its potential role in breast cancers stem cells (BCSCs) have not been explored. Emerging evidence suggests that mucin play important roles in tumor metastasis and drug resistance. MicroRNAs (miRNA), small noncoding RNAs that play critical roles in normal stem cell functions during development, have emerged as important regulators of BCSCs as well.

Methods

Muc positive (+)/(-) cells were isolated from patient-derived cancer (n = 25), and normal BC tissues (n = 15) and propagated in nonadhesive suspension cell culture to assess their phenotypic characteristics. Further miRNAs expression profiling was done by using microRNA TaqMan® Low Density Array Cards v2.0 (TLDA cards A, Invitrogen), based on qReal-Time PCR array.

Results

Upon Muc1(+) selection, we have found rare subpopulation of undifferentiated cells expressing Muc1 in 70% BC tissue samples. These cells were growing indefinitely (∼28 weeks) as mammospheres in serum-free cell culture medium and also shown high ALDH activity and Muc1, EpCAM, CD49f, and CD44 + /CD24- expression in comparison to Muc1(-) subpopulations (p < 0.05). Among altered miRNAs, Muc(+) BCSCs were showing significantly downregulated expression of miR-125b as compared to adhered and Muc(-) cell population. In addition downregulated expression of miR-125b in most BCSCs and clinical specimens of BC were noted, and correlated with cellular differentiation and drug resistance potential in BC patients. We afterward demonstrated that miR-125b overexpression attenuated the BCSC's self renewal and proliferation potential along with Muc1, Dicer 1, Prominin1, ELF4EBP1, ALDH4A1, DDR1, KRAS and BCL2 expression, whereas knockdown of miR-125b promoted these.

Conclusions

These findings suggest that ectopic expression of miR-125b provides a promising strategy to inhibit cancer stem cells.

Clinical trial identification

none

Disclosure

All authors have declared no conflicts of interest.