Newly Identified Members of FGFR1 Splice Variants Engage in Cross-talk with AXL/AKT Axis in Salivary Adenoid Cystic Carcinoma.

TitleNewly Identified Members of FGFR1 Splice Variants Engage in Cross-talk with AXL/AKT Axis in Salivary Adenoid Cystic Carcinoma.
Publication TypeJournal Article
Year of Publication2021
AuthorsHumtsoe JO, Kim H-S, Leonard B, Ling S, Keam B, Marchionni L, Afsari B, Considine M, Favorov AV, Fertig EJ, Kang H, Ha PK
JournalCancer Res
Volume81
Issue4
Pagination1001-1013
Date Published2021 02 15
ISSN1538-7445
KeywordsAnimals, Carcinoma, Adenoid Cystic, Cell Line, Tumor, Female, Gene Expression Regulation, Neoplastic, Humans, Mice, Mice, Inbred NOD, Mice, Transgenic, Protein Isoforms, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, Receptor Cross-Talk, Receptor Protein-Tyrosine Kinases, Receptor, Fibroblast Growth Factor, Type 1, Salivary Gland Neoplasms, Salivary Glands, Signal Transduction
Abstract

Adenoid cystic carcinoma (ACC) is the second most common malignancy of the salivary gland. Although characterized as an indolent tumor, ACC often leads to incurable metastatic disease. Patients with ACC respond poorly to currently available therapeutic drugs and factors contributing to the limited response remain unknown. Determining the role of molecular alterations frequently occurring in ACC may clarify ACC tumorigenesis and advance the development of effective treatment strategies. Applying Splice Expression Variant Analysis and outlier statistics on RNA sequencing of primary ACC tumors and matched normal salivary gland tissues, we identified multiple alternative splicing events (ASE) of genes specific to ACC. In ACC cells and patient-derived xenografts, was a uniquely expressed ASE. Detailed PCR analysis identified three novel, truncated, intracellular domain-lacking variants (). Cloning and expression analysis suggest that the three FGFR1v are cell surface proteins, that expression of FGFR1v augmented pAKT activity, and that cells became more resistant to pharmacologic FGFR1 inhibitor. FGFR1v-induced AKT activation was associated with AXL function, and inhibition of AXL activity in FGFR1v knockdown cells led to enhanced cytotoxicity in ACC. Moreover, cell killing effect was increased by dual inhibition of AXL and FGFR1 in ACC cells. This study demonstrates that these previously undescribed FGFR1v cooperate with AXL and desensitize cells to FGFR1 inhibitor, which supports further investigation into combined FGFR1 and AXL inhibition as an effective ACC therapy.This study identifies several FGFR1 variants that function through the AXL/AKT signaling pathway independent of FGF/FGFR1, desensitizing cells to FGFR1 inhibitor suggestive of a potential resistance mechanism in ACC. SIGNIFICANCE: This study identifies several FGFR1 variants that function through the AXL/AKT signaling pathway independent of FGF/FGFR1, desensitizing cells to FGFR1 inhibitor, suggestive of a potential resistance mechanism in ACC.

DOI10.1158/0008-5472.CAN-20-1780
Alternate JournalCancer Res
PubMed ID33408119
Grant ListP30 CA006973 / CA / NCI NIH HHS / United States
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