Nucleolar protein DCAF13 promotes non–small cell lung cancer cell proliferation via facilitating rDNA transcription and ribosome biogenesis

The nucleolus is an important nonmembranous organelle within the nucleus and is responsible for ribosome biogenesis. This process is frequently upregulated in tumors to support elevated protein synthesis and sustain tumor growth. The transcription of ribosomal DNA (rDNA) into pre-45S rRNA, a rate-limiting step in ribosomal biogenesis, has been reported to be enhanced to drive the progression of non-small cell lung cancer (NSCLC). However, the mechanism that upregulating rDNA transcription in NSCLC remains unclear. Here, we show that rDNA transcript levels were increased in NSCLC tumor tissues. Reduction of rDNA transcription by CX-5461, an RNA polymerase I inhibitor, significantly inhibited NSCLC cell proliferation. We found that the expression level of DDB1- and CUL4-associated factor 13 (DCAF13), a nucleolar protein, positively correlated with that of pre-45S rRNA. DCAF13 knockdown impairs rDNA transcription, ribosome biogenesis, and protein synthesis, indicating that DCAF13 participates in rDNA transcription. Mechanistically, DCAF13 interacts directly with TAF1A, a component of the RNA polymerase I preinitiation complex. This interaction is necessary for preinitiation complex assembly. In addition, DCAF13 is highly expressed in NSCLC, and its expression is negatively correlated with the overall survival in NSCLC patients. DCAF13 knockout inhibited NSCLC cell proliferation, colony formation, and migration, indicating that DCAF13 is a poor prognosis indicator of NSCLC. In summary, we found that DCAF13 promotes NSCLC cell proliferation by coordinating with TAF1A to regulate rDNA transcription and maintain high ribosome biogenesis.