The small-molecule protein ligand interface stabiliser E7820 induces differential cell line specific responses of integrin α2 expression

Abstract

Background The mechanism of small-molecule stabilised protein-protein interactions is of growing interest in the pharmacological discovery process. A plethora of different substances including the aromatic sulphonamide E7820 have been identified to act by such a mechanism. The process of E7820 induced CAPERα degradation and the resultant transcriptional down regulation of integrin α2 expression has previously been described for a variety of different cell lines and been made responsible for E7820’s antiangiogenic activity. Currently the application of E7820 in the treatment of various malignancies including pancreas carcinoma and breast cancer is being investigated in pre-clinical and clinical trials. It has been shown, that integrin α2 deficiency has beneficial effects on bone homeostasis in mice. To transfer E7820 treatment to bone-related pathologies, as non-healing fractures, osteoporosis and bone cancer might therefore be beneficial. However, at present no data is available on the effect of E7820 on osseous cells or skeletal malignancies. Methods Pre-osteoblastic (MC3T3 and Saos-2) cells and endothelial (eEnd2 cells and HUVECs) cells, each of human and murine origin respectively, were investigated. Vitality assay with different concentrations of E7820 were performed. All consecutive experiments were done at a final concentration of 50 ng/ml E7820. The expression and production of integrin α2 and CAPERα were investigated by quantitative real-time PCR and western blotting. Expression of CAPERα splice forms was differentiated by semi-quantitiative reverse transcriptase PCR. Results Here we present the first data showing that E7820 can increase integrin α2 expression in the pre-osteoblast MC3T3 cell line whilst also reproducing canonical E7820 activity in HUVECs. We show that the aberrant activity of E7820 in MC3T3 cells is likely due to differential activity of CAPERα at the integrin α2 promoter, rather than due to differential CAPERα degradation or differential expression of CAPERα spliceforms. Conclusion The results presented here indicate that E7820 may not be suitable to treat certain malignancies of musculoskeletal origin, due to the increase in integrin α2 expression it may induce. Further investigation of the differential functioning of CAPERα and the integrin α2 promoter in cells of various origin would however be necessary to more clearly differentiate between cell lines that will positively respond to E7820 from those that will not.

Gene Coexpression Network Characterizing Microenvironmental Heterogeneity and Intercellular Communication in Pancreatic Ductal Adenocarcinoma: Implications of Prognostic Significance and Therapeutic Target

“…To explore whether and to what extent targeting ITGA2 influences PDAC development, we employed Pdx1-Cre + , Kras G12D (KC) mice for in vivo inhibitor management. The mice were orally treated with the ITGA2 inhibitor E7820 ( 39 ), and the affected pancreas area was quantified. It appeared that E7820 essentially diminished pancreatic lesions without profoundly influencing body weights ( Figure 7C ; Supplementary Figure 9A ).…”

“…To determine a clinically feasible way to target ITGA2, the ITGA2 inhibitor E7820, which has been used in clinical trials ( 39 , 59 – 61 ), was chosen for testing. In PDAC, the effect of E7820 is unclear.…”

Inflammation as a driver of hematological malignancies

“…E7820, another sulfonamide, is in phase II clinical trials for solid cancers ( 124 ). It acts as an inhibitor of Integrin α2 (ITGA2), which plays a key role in methotrexate-induced epithelial-mesenchymal transition (EMT) in alveolar epithelial cells ( 125 ). E7820 also selectively targets RNA splicing factor RBM39 for proteasomal degradation via DCAF15-E3-ubiquitin ligase.…”

“…E7820 also selectively targets RNA splicing factor RBM39 for proteasomal degradation via DCAF15-E3-ubiquitin ligase. This action of E7820 has been observed to induce rapid loss of RBM39, accumulation of splicing errors, and growth inhibition in a DCAF15-dependent manner ( 125 , 126 ). Interestingly, DCAF15 is found to be more highly expressed in Acute Myeloid Leukemia (AML) patient samples compared to normal hematopoietic progenitors.…”