Effects of Roseoflavin and/or Trametinib Treatment on 3D-Cultured PDAC Cell Lines

Pancreatic ductal adenocarcinoma (PDAC) remains a formidable challenge with a survival rate of approximately 10%, largely due to inadequate diagnostic and therapeutic options. To identify novel therapeutic targets for PDAC, we have previously developed a Drosophila model, '4-hit' fly, which mimics the four gene alterations characteristic of PDAC: KRAS, TP53, CDKN2A, and SMAD4. Through a whole-body genetic screening using the 4-hit fly, we discovered that riboflavin (RF) pathway represents a novel potential target for PDAC treatment. Expression analysis revealed that four out of five RF pathway-related genes were upregulated in PDAC compared to non-tumor pancreas. Inhibition of RF pathway resulted in metabolic changes, notably decreased mitochondrial respiratory chain activity, and subsequently suppressed PDAC cell proliferation. Furthermore, a combination therapy using the RF pathway inhibitor roseoflavin with MEK inhibitor trametinib significantly suppressed the expansion of human PDAC xenografts and spheroid formation more effectively than either treatment alone. These findings suggest that dual inhibition of RF pathway and MEK could offer a novel therapeutic strategy for PDAC. Pancreatic cancer cells were cultured in three dimensions in a methylcellulose-containing medium for three days before treatment with roseoflavin and/or trametinib. Spheroid samples were collected one day post-treatment and analyzed using RNA sequencing.