3D collagen high-throughput screen identifies drugs that induce epithelial polarity and enhance chemotherapy response in colorectal cancer

Loss of polarity is a hallmark of cancer, and the related epithelial-to-mesenchymal transition (EMT) phenotype also impacts prognosis and therapy outcomes, particularly in colorectal cancer (CRC). However, the mechanisms and drugs that impact these morphological changes are understudied, due to the complete failure of typical live/dead 2D high-throughput screens to capture morphology or the lack of robustness of 3D screens. We designed a high-throughput screen using 3D type I collagen cultures of CRC cells to assess morphological changes in colonies and identified several FDA-approved drugs that re-epithelialize CRC colonies One of these drugs, azithromycin, increased colony circularity, enhanced E-cadherin membrane localization and ZO-1 localization to tight junctions, caused transcriptomic changes consistent with downregulation of epithelial-to-mesenchymal transition, and elevated sensitivity to the chemotherapeutic, irinotecan. A retrospective analysis of patient data demonstrated that the use of azithromycin in patients undergoing treatment for CRC with irinotecan had improved the 5-year survival compared to the chemotherapy alone. These results highlight the importance of morphological screens to identify novel drug candidates and synergistic mechanisms. SC cells, a CRC cell lines known to form spiky colonies, were seeded in type I collagen cultures and incubated with no drug (control), azithromycin, clindamycin, or linezolid for 12 days. RNA was extracted from colonies and RNA seq profiling completed.