Yishen Quyu Lishi Formula suppresses multiple myeloma growth via ERK/mTOR-mediated inhibition of protective autophagy and induction of apoptosis.

OBJECTIVES: To evaluate the anti-tumor effect of Yishen Quyu Lishi Formula (YSQYLSF) on multiple myeloma (MM) and to determine whether this effect is mediated by extracellular signal-regulated kinase/mammalian target of rapamycin (ERK/mTOR)-regulated protective autophagy and apoptosis. METHODS: H929 xenograft-bearing nude mice were treated with YSQYLSF, bortezomib (BO), or their combination for 21 days. Tumor growth, body weight, histopathology, immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT-qPCR), Western blotting, and ribonucleic acid sequencing (RNA-Seq) were performed. H929 cells were further used for cell viability assays, green fluorescent protein-microtubule-associated protein 1 light chain 3 (GFP-LC3) imaging, flow cytometry, Western blotting, and rapamycin rescue assays. RESULTS: YSQYLSF reduced xenograft growth and, when combined with BO, produced a potent anti-tumor effect without significant weight loss or obvious liver and kidney damage. RNA-Seq identified 802 differentially expressed genes, with enrichment in mitogen-activated protein kinase (MAPK), mammalian target of rapamycin (mTOR), autophagy, apoptosis, inflammatory, and immune-related pathways. YSQYLSF increased the phosphorylated ERK/ERK and phosphorylated mTOR/mTOR ratios, decreased LC3-II/LC3-I, increased p62 accumulation, and enhanced the Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios. In vitro, YSQYLSF reduced H929 cell viability, decreased autophagosome formation, and promoted apoptosis. Rapamycin partially restored autophagy and attenuated apoptosis. CONCLUSIONS: YSQYLSF inhibits MM growth by activating the ERK/mTOR pathway, suppressing protective autophagy, and promoting mitochondrial apoptosis. Transcriptomic data also suggest additional immune- and inflammation-related mechanisms that require further validation.