Proteomic screening identifies calreticulin as a MIR-27a direct target repressing MHC class I cell surface exposure in colorectal cancer

Tommaso Colangelo, G. Polcaro, P. Ziccardi, Biagio Pucci, L. Muccillo, Mario Galgani, Alessandra Fucci, Maria Rita Milone, Alfredo Budillon, Marianna Santopaolo, Carolina Votino, Massimo Pancione, Monica Binaschi, Mario Bigioni, Carlo Alberto Maggi, Matteo Fassan, Carmelo Laudanna, Lina Sabatino, Vittorio Colantuoni

Research output: Contribution to journalArticlepeer-review


Impairment of the immune response and aberrant expression of microRNAs are emerging hallmarks of tumour initiation/progression, in addition to driver gene mutations and epigenetic modifications. We performed a preliminary survey of independent adenoma and colorectal cancer (CRC) miRnoma data sets and, among the most dysregulated miRNAs, we selected miR-27a and disclosed that it is already upregulated in adenoma and further increases during the evolution to adenocarcinoma. To identify novel genes and pathways regulated by this miRNA, we employed a differential 2DE-DIGE proteome analysis. We showed that miR-27a modulates a group of proteins involved in MHC class I cell surface exposure and, mechanistically, demonstrated that calreticulin is a miR-27a direct target responsible for most downstream effects in epistasis experiments. In vitro miR-27a affected cell proliferation and angiogenesis; mouse xenografts of human CRC cell lines expressing different miR-27a levels confirmed the protein variations and recapitulated the cell growth and apoptosis effects. In vivo miR-27a inversely correlated with MHC class I molecules and calreticulin expression, CD8+ T cells infiltration and cytotoxic activity (LAMP-1 exposure and perforin release). Tumours with high miR-27a, low calreticulin and CD8+ T cells' infiltration were associated with distant metastasis and poor prognosis. Our data demonstrate that miR-27a acts as an oncomiRNA, represses MHC class I expression through calreticulin downregulation and affects tumour progression. These results may pave the way for better diagnosis, patient stratification and novel therapeutic approaches.

Original languageEnglish
Article numbere2120
JournalCell Death and Disease
Issue number2
Publication statusPublished - Feb 25 2016

ASJC Scopus subject areas

  • Cell Biology
  • Immunology
  • Cancer Research
  • Cellular and Molecular Neuroscience


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