Targeting treatment resistant breast cancer stem cells with FKBPL and its peptide derivative, AD-01, via the CD44 pathway

Lana McClements, Anita Yakkundi, Angelos Papaspyropoulos, Hannah Harrison, Matthew P Ablett, Puthen V Jithesh, Hayley D McKeen, Rachel Bennett, Christopher Donley, Adrien Kissenpfennig, Stuart McIntosh, Helen O McCarthy, Eric O'Neill, Robert B Clarke, Tracy Robson

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

PURPOSE: FKBPL and its peptide derivative, AD-01, have already demonstrated tumour growth inhibition and CD44 dependent anti-angiogenic activity. Here we explore the ability of AD-01 to target CD44 positive breast cancer stem cells (BCSCs). EXPERIMENTAL DESIGN: Mammosphere assays and flow cytometry were utilized to analyse the effect of FKBPL overexpression/knockdown and AD-01 treatment ± other anti-cancer agents on BCSCs using breast cancer cell lines (MCF-7/MDA-231/ZR-75), primary patient samples and xenografts. Delays in tumour initiation were evaluated in vivo. The anti-stem cell mechanisms were determined using clonogenic assays, qPCR and immunofluorescence. RESULTS: AD-01 treatment was highly effective at inhibiting the BCSC population by reducing mammosphere forming efficiency (MFE) and ESA+/CD44+/CD24- or ALDH+ cell subpopulations in vitro and tumour initiation in vivo. The ability of AD-01 to inhibit the self-renewal capacity of BCSCs was confirmed; mammospheres were completely eradicated by the third generation. The mechanism appears to be due to AD-01-mediated BCSC differentiation demonstrated by a significant decrease in the number of holoclones and an associated increase in meroclones/paraclones; the stem cell markers, Nanog, Oct4 and Sox2, were also significantly reduced. Furthermore, we demonstrated additive inhibitory effects when AD-01 was combined with the Notch inhibitor, DAPT. AD-01 was also able to abrogate a chemo- and radiotherapy induced enrichment in BCSCs. Finally, FKBPL knockdown led to an increase in Nanog/Oct4/Sox2 and an increase in BCSCs, highlighting a role for endogenous FKBPL in stem cell signalling. CONCLUSIONS: AD-01 has dual anti-angiogenic and anti-BCSC activity which will be advantageous as this agent enters clinical trial.
Original languageEnglish
Pages (from-to)3881-3893
Number of pages12
JournalClinical Cancer Research
Volume19
Issue number14
DOIs
Publication statusPublished - 05 Jun 2013

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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