The Regulation of SPRY4 Intronic Transcript 1 (SPRY4-IT1) on KIT Signaling and Imatinib Resistance of Gastrointestinal Stromal Tumor (GIST) Cells

Yuanyuan Yu (The General Hospital of Ningxia Medical University, Shengli Street 804, Yinchuan)
Zongying Jiang (The General Hospital of Ningxia Medical University, Shengli Street 804, Yinchuan)
Sien Zhao (School of Basic Medical Sciences, Ningxia Medical University, Shengli Street 1160, Yinchuan)
Cuiyun Liu (The General Hospital of Ningxia Medical University, Shengli Street 804, Yinchuan)
Jinhai Ma (The General Hospital of Ningxia Medical University, Shengli Street 804, Yinchuan)
Shujing Li (The General Hospital of Ningxia Medical University, Shengli Street 804, Yinchuan)

The Indonesian Biomedical Journal
Vol 16, No 4 (2024)

BACKGROUND: SPRY4 intronic transcript 1 (SPRY4-IT1), is a long non-coding RNA coded by the intron of SPRY4. SPRY4 is highly expressed in gastrointestinal stromal tumor (GIST) and inhibits the tumorigenesis of GIST, but whether SPRY4-IT1 regulates the tumorigenesis of GIST or not remains unclear. Therefore, in this study, the regulation of SPRY4-IT1 expression and its role in GIST will be investigated.METHODS: GIST-T1 cells, and Ba/F3 cells which express KIT proto-oncogene (KIT) and SPRY4-IT1 were used as cell models. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to examine mRNA expression, while the protein expression and signal transduction were examined by western blot. The association between SPRY4-IT1 and KIT was examined by pull down of KIT and PCR. Cell proliferation, survival, and cell cycle progression were examined by cell counting kit-8 (CCK8) and flow cytometry.RESULTS: KIT mutants increased the expression of SPRY4-IT1 in GIST. SPRY4-IT1 bound to KIT, also enhanced the activation and expression of both wild-type KIT and primary KIT mutants, therefore increasing the activation of downstream signaling proteins AKT and ERK of KIT, GIST cell survival, and proliferation. In addition, SPRY4-IT1 reduced the sensitivity of wild-type KIT, or primary KIT mutants to the first-line targeted therapeutic drug of GIST, imatinib, which can inhibit KIT activation. Gaining drug-resistant secondary KIT mutants might be one of the main reasons of GIST recurrence after targeted therapy. Similar to wild-type KIT and primary KIT mutants, the activation and expression of secondary KIT mutants and their resistance to imatinib were also increased by SPRY4-IT1.CONCLUSION: The results indicated positive feedback between SPRY4-IT1 and wild-type KIT, primary KIT mutants or secondary KIT mutants, and the upregulation of AKT and ERK activation by SPRY4-IT1 in GIST cells, providing a new insight in the KIT signaling regulation in GIST, and the resistance of GIST to targeted therapy.KEYWORDS: SPRY4-IT1, KIT, GIST, SPRY4, signaling