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MATILDE TODARO

PI3K-driven HER2 expression is a potential therapeutic target in colorectal cancer stem cells

  • Autori: Mangiapane L.R.; Nicotra A.; Turdo A.; Gaggianesi M.; Bianca P.; Di Franco S.; Sardina D.S.; Veschi V.; Signore M.; Beyes S.; Fagnocchi L.; Fiori M.E.; Bongiorno M.R.; Lo Iacono M.; Pillitteri I.; Ganduscio G.; Gulotta G.; Medema J.P.; Zippo A.; Todaro M.; De Maria R.; Stassi G.
  • Anno di pubblicazione: 2021
  • Tipologia: Articolo in rivista
  • OA Link: http://hdl.handle.net/10447/472524

Abstract

Objective: Cancer stem cells are responsible for tumour spreading and relapse. Human epidermal growth factor receptor 2 (HER2) expression is a negative prognostic factor in colorectal cancer (CRC) and a potential target in tumours carrying the gene amplification. Our aim was to define the expression of HER2 in colorectal cancer stem cells (CR-CSCs) and its possible role as therapeutic target in CRC resistant to anti-epidermal growth factor receptor (EGFR) therapy. Design: A collection of primary sphere cell cultures obtained from 60 CRC specimens was used to generate CR-CSC mouse avatars to preclinically validate therapeutic options. We also made use of the ChIP-seq analysis for transcriptional evaluation of HER2 activation and global RNA-seq to identify the mechanisms underlying therapy resistance. Results: Here we show that in CD44v6-positive CR-CSCs, high HER2 expression levels are associated with an activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, which promotes the acetylation at the regulatory elements of the Erbb2 gene. HER2 targeting in combination with phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase kinase (MEK) inhibitors induces CR-CSC death and regression of tumour xenografts, including those carrying Kras and Pik3ca mutation. Requirement for the triple targeting is due to the presence of cancer-associated fibroblasts, which release cytokines able to confer CR-CSC resistance to PI3K/AKT inhibitors. In contrast, targeting of PI3K/AKT as monotherapy is sufficient to kill liver-disseminating CR-CSCs in a model of adjuvant therapy. Conclusions: While PI3K targeting kills liver-colonising CR-CSCs, the concomitant inhibition of PI3K, HER2 and MEK is required to induce regression of tumours resistant to anti-EGFR therapies. These data may provide a rationale for designing clinical trials in the adjuvant and metastatic setting.