The anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) cetuximab and panitumumab are effective in a subset of RAS/BRAF wild-type (WT) metastatic colorectal cancers (mCRCs) patients. Despite an accurate RAS-driven selection, not all patients will respond to EGFR inhibitors and the onset of secondary resistance limits their clinical benefit.
With the aim of developing effective preclinical models for testing possible strategies to overcome acquired resistance to EGFR blockade, we have generated a series of human colon cancer cell lines with in vitro and in vivo acquired resistance to anti-EGFR inhibitors. To better investigate the differentially expressed proteins involved in EGFR resistance, we applied an advanced quantitative proteomic approach based on TMT isobaric labeling and nano-liquid chromatography coupled with high resolution tandem mass spectrometry (MS/MS).
To evaluate changes in protein expression we have used human CRC cell line cetuximab-sensitive GEO, as well as its derived cell line with acquired resistance to cetuximab GEO-CR. By MS/MS, we have identified and quantified 2455 proteins; 53 proteins were found to be differentially expressed in GEO-CR compared to GEO cells. Only 11 proteins were found to be high regulated in GEO-CR, among these we focused our attention on the inhibition factor of macrophage migration (MIF) for its relevance in CRC tumorigenesis. To explore its involvement in resistance to cetuximab in CRC cell line, we have performed an MTT assay with two MIF-antagonists, ISO1 a cell-permeable inhibitor of MIF tautomerase and 4-IPP, a selective MIF inhibitor that blocks MIF and its receptor, CD74, internalization. GEO-CR cell line was treated with two MIF antagonists alone and in combination with cetuximab. Only the combined treatment with cetuximab and 4-IPP induced a synergistic antiproliferative and apoptotic effects.
These results suggest that MIF overexpression is involved in acquired resistance to cetuximab and the inhibition of EGFR and MIF could be a strategy for overcoming anti-EGFR resistance in patients with CRC.
Clinical trial identification
Legal entity responsible for the study
Università Degli Studi della Campania "Luigi Vanvitelli".
Has not received any funding.
All authors have declared no conflicts of interest.