Combination of Tipifarnib and Sunitinib Overcomes Renal Cell Carcinoma Resistance to Tyrosine Kinase Inhibitors via Tumor-Derived Exosome and T Cell Modulation

• Published in: Cancers Vol. 14; no. 4; p. 903
• Main Authors: Greenberg, Jacob W., Kim, Hogyoung, Ahn, Miae, Moustafa, Ahmed A., Zhou, He, Barata, Pedro C., Boulares, A. Hamid, Abdel-Mageed, Asim B., Krane, Louis S.
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11.02.2022; MDPI
• Subjects: Biosynthesis; Cell proliferation; Chemoresistance; Chemotherapy; Communication; Cytotoxicity; Drug dosages; Drug resistance; Exosomes; Immunotherapy; Kidney cancer; Kinases; L1 protein; Lymphocytes; Lymphocytes T; Medical prognosis; Metastases; Metastasis; Patients; PD-L1 protein; Penicillin; Renal cell carcinoma; T cell receptors; Tyrosine kinase inhibitors; Ultracentrifugation; St Louis Missouri; United States > US; sunitinib; renal cell carcinoma; extracellular vesicles; cell culture; exosomes; ERK pathway; PD-L1; TKI resistance; tipifarnib; resistance
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers14040903

Background: Tyrosine kinase inhibitors (TKI) were initially demonstrated as an efficacious treatment for renal cell carcinoma (RCC). However, after a median treatment length of 14 months, a vast majority of patients develop resistance. This study analyzed a combination therapy of tipifarnib (Tipi) + sunitinib that targeted exosome-conferred drug resistance. Methods: 786-O, 786-O-SR (sunitinib resistant), A498, A498-SR, Caki-2, Caki-2-SR, and 293T cells were cultured. Exosomes were collected using differential ultracentrifugation. Cell proliferation, Jurkat T cell immune assay, and immunoblot analysis were used for downstream analysis. Results: SR exosomes treatment displayed a cytotoxic effect on immune cells. This cytotoxic effect was associated with increased expression of PD-L1 on SR exosomes when compared to sunitinib-sensitive (SS) exosomes. Additionally, Tipi treatment downregulated PD-L1 expression on exosomes derived from SR cell lines. Tipi’s ability to downregulate PD-L1 in exosomes has a significant application within patients. Exosomes collected from patients with RCC showed increased PD-L1 expression over subjects without RCC. Next, exosome concentrations were then compared after Tipi treatment, with all SS cell lines displaying an even greater reduction. On immunoblot assay, 293T cells showed a dose-dependent increase in Alix with no change in either nSMase or Rab27a. Conversely, all the SS and SR cell lines displayed a decrease in all three markers. After a cell proliferation employed a 48-h treatment on all SS and SR cell lines, the drug combination displayed synergistic ability to decrease tumor growth. Conclusions: Tipifarnib attenuates both the exosome endosomal sorting complex required for endosomal sorting complex required for transport (ESCRT)-dependent and ESCRT-independent pathways, thereby blocking exosome biogenesis and secretion as well as downregulating PD-L1 on SS and SR cells.