FAM167A is a key molecule to induce BCR-ABL-independent TKI resistance in CML via noncanonical NF-κB signaling activation.

backgroundBCR-ABL-independent drug resistance is a barrier to curative treatment of chronic myeloid leukemia (CML). However, the molecular pathways underlying BCR-ABL-independent tyrosine kinase inhibitor (TKI) resistance remain unclear.

methodsIn silico bioinformatic analysis was performed to identify the most active transcription factor and its inducer that contribute to BCR-ABL-independent TKI resistance. Tandem mass spectrometry analysis was performed to identify the receptor for the noncanonical NF-κB activator FAM167A. In vitro and in vivo mouse experiments revealed detailed molecular insights into the functional role of the FAM167A-desmoglein-1 (DSG1) axis in BCL-ABL-independent TKI resistance. CML cells derived from CML patients were analyzed using quantitative reverse transcription PCR and flow cytometry.

resultsWe found that NF-κB had the greatest effect on differential gene expression of BCR-ABL-independent TKI-resistant CML cells. Moreover, we found that the previously uncharacterized protein FAM167A activates the noncanonical NF-κB pathway and induces BCR-ABL-independent TKI resistance. Molecular analyses revealed that FAM167A activates the noncanonical NF-κB pathway by binding to the cell adhesion protein DSG1 to upregulate NF-κB-inducing kinase (NIK) by blocking its ubiquitination. Neutralization of FAM167A in a mouse tumor model reduced noncanonical NF-κB activity and restored sensitivity of cells to TKIs. Furthermore, FAM167A and surface DSG1 levels were highly upregulated in CD34

conclusionsThese results reveal that FAM167A acts as an essential factor for BCR-ABL-independent TKI resistance in CML by activating the noncanonical NF-κB pathway. In addition, FAM167A may serve as an important target and biomarker for BCR-ABL-independent TKI resistance.