Targeting sphingosine kinase 1/2 by a novel dual inhibitor SKI-349 suppresses non-small cell lung cancer cell growth

Abstract

Sphingosine kinase 1 (SphK1) and sphingosine kinase (SphK2) are both important therapeutic targets of non-small cell lung cancer (NSCLC). SKI-349 is a novel, highly efficient and small molecular SphK1/2 dual inhibitor. Here in primary human NSCLC cells and immortalized cell lines, SKI-349 potently inhibited cell proliferation, cell cycle progression, migration and viability. The dual inhibitor induced mitochondrial depolarization and apoptosis activation in NSCLC cells, but it was non-cytotoxic to human lung epithelial cells. SKI-349 inhibited SphK activity and induced ceramide accumulation in primary NSCLC cells, without affecting SphK1/2 expression. SKI-349-induced NSCLC cell death was attenuated by sphingosine-1-phosphate and by the SphK activator K6PC-5, but was potentiated by the short-chain ceramide C6. Moreover, SKI-349 induced Akt-mTOR inactivation, JNK activation, and oxidative injury in primary NSCLC cells. In addition, SKI-349 decreased bromodomain-containing protein 4 (BRD4) expression and downregulated BRD4-dependent genes (Myc, cyclin D1 and Klf4) in primary NSCLC cells. At last, SKI-349 (10 mg/kg) administration inhibited NSCLC xenograft growth in nude mice. Akt-mTOR inhibition, JNK activation, oxidative injury and BRD4 downregulation were detected in SKI-349-treated NSCLC xenograft tissues. Taken together, targeting SphK1/2 by SKI-349 potently inhibits NSCLC cell growth in vitro and in vivo.

Recent progress in targeted therapy for non-small cell lung cancer

“…Moreover, it was demonstrated that SphK1 promotes the proliferation of NSCLC cells by regulating PI3K/Akt pathway. SphK1 activates the PI3K/AKT/NF-κB pathway and increases the expression of theapoptotic and migration -associated genes such as Bcl-2, MMP2 and cyclin D1 (Figure 3) (Song et al, 2011;Xue et al, 2022).…”

“…SKI-349 is a novel, highly efficient small-molecule SphK1/2 dual inhibitor. It has been shown to be not cytotoxic to human lung epithelial cells and to induce the apoptosis of NSCLC cells in experiments performed in vitro and in vitro (Xue et al, 2022).…”

Identification of the mitochondrial protein ADCK2 as a therapeutic oncotarget of NSCLC

“…NSCLC cells or the lung epithelial cells were seeded at optimal cell density and cultured for indicated time periods. CCK-8, colony formation assay, "Transwell" assays, nuclear EdU staining, cell immunofluorescence staining, and the single strand DNA (ssDNA) ELISA were described early [17,18,[21][22][23]. Detecting measuring mitochondrial membrane potential by JC-1, the caspase activity assays, Histone DNA ELISA, and TUNEL nuclear staining were reported early [17,18].…”

“…Lipid peroxidation was tested by a thiobarbituric acid reactive substance (TBAR) kit (Cayman Chemical, MI) according to the attached protocol. Immunohistochemistry (IHC) protocols were reported early [25].The detailed protocols for the Western blotting and the qRT-PCR assays were described previously [17,18,21]. The mRNA primer pair sequences were described previously [13].…”

“…All laboratory athymic nude mice (five-six week old, 18.3-19.2g weight, half male half female) were described early [21]. NSCLC cells (at three million cells per mouse, in 120 μL basic medium-Matrigel mix) were injected subcutaneously into flanks of mice.…”