115P - Inhibition of KLF5 reduces tumor growth and sensitizes to chemotherapy-induced cell death in experimental models of cholangiocarcinoma

Background

Cholangiocarcinoma (CCA) comprises a heterogeneous group of cancers with bad prognosis. Krüppel-like factors (KLF) are a family of transcription factors involved in organogenesis, differentiation and cellular homeostasis. Here, we studied the role of KLF5 in CCA development and evaluated the therapeutic potential of its inhibition.

Methods

KLF5 expression was measured in human CCA tissues [Copenhagen (n=210), TCGA (n=36), Job (n=78), TIGER-LC (n=90) and San Sebastian cohorts (n=12)] and cell lines. KLF5 ^-/- CCA cells were created by CRISPR/Cas9. The functional effects of KLF5 genetic silencing with CRISPR technology, or chemical inhibition with ML264, were evaluated in vitro and in vivo.

Results

KLF5 expression was upregulated in human CCA tissues from 5 different patient cohorts compared to surrounding normal liver tissue. High KLF5 levels correlated with lymph node invasion and worse overall survival. In vitro, KLF5 protein and mRNA levels were overexpressed in human CCA cells compared to normal human cholangiocytes. Functionally, KLF5 ^-/- CCA cells displayed decreased cell proliferation, migration, invasion and colony formation while promoting cell cycle arrest at G1/S and apoptosis in vitro, when compared to control cells. In agreement, KLF5 ^-/- CCA cells did not develop any tumor after subcutaneous or orthotopic injection in a xenograft animal model of CCA. Likewise, chemical inhibition of KLF5 with ML264 hampered CCA cells proliferation and migration in vitro and blocked tumor growth in vivo. Lastly, both genetic and chemical inhibition of KLF5 sensitized CCA cells to chemotherapy-induced apoptosis in vitro, and the combination of gemcitabine + cisplatin and ML264 completely halted CCA tumor growth in mice. Accordingly, KLF5 ^-/- CCA display altered levels of several proteins related to chemoresistance when compared to control cells, that were shown to significantly correlate with KLF5 expression in human CCA tissues.

Conclusions

Increased KLF5 is a general event in CCA, contributing to cancer progression and chemoresistance. KLF5 inhibition with ML264 may represent a potential therapeutic strategy for CCA.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Biodonostia Health Research Institute.

Funding

Carlos III Health Insistute - FIS Project.

Disclosure

All authors have declared no conflicts of interest.