SPHK1 promotes metastasis of thyroid carcinoma through activation of the S1P/S1PR3/Notch signaling pathway

Sphingosine kinase 1 contributes to doxorubicin resistance and glycolysis in osteosarcoma

Osteosarcoma (OS) is one of the most common and aggressive malignancies in children and adolescents worldwide. Sphingosine kinase 1 (SphK1) has recently been reported to serve a role in OS progression. The present study aimed to investigate the role of SphK1 in the development of chemoresistance and glycolysis in OS cell lines. SphK1 expression levels in OS cell lines (U2OS, MG63 and SaoS2) were analyzed using western blotting and reverse transcription-quantitative PCR (RT-qPCR). A cell survival assay was conducted to determine doxorubicin-resistance in OS cells, and glycolysis was also evaluated. SphK1 expression was increased in the U2OS and SaoS2 cell lines, and both cell lines were more resistant to doxorubicin when compared with the MG63 cell line. SphK1 knockdown or overexpression altered doxorubicin resistance and the viability of OS cell lines. In addition, hypoxia inducible factor-1α (HIF-1α) expression was positively associated with SphK1 expression, and partly mediated SphK1-induced effects on doxorubicin resistance and glycolysis. The present study suggested that SphK1 participated in the development of doxorubicin resistance and contributed to glycolysis in OS cells by regulating HIF-1α expression. However, further studies investigating the application of SphK1 associated therapies for patients with OS are required.

High FA2H and UGT8 transcript levels predict hydroxylated hexosylceramide accumulation in lung adenocarcinoma

Lung cancer causes more deaths than any other cancer. Sphingolipids encompass metabolically interconnected species whose balance has pivotal effects on proliferation, migration, and apoptosis. In this study, we paralleled quantification of sphingolipid species with quantitative (q)PCR analyses of metabolic enzymes in order to identify dysregulated routes of sphingolipid metabolism in different subtypes of lung cancers. Lung samples were submitted to histopathological reexamination in order to confirm cancer type/subtype, which included adenocarcinoma histological subtypes and squamous cell and neuroendocrine carcinomas. Compared with benign lesions and tumor-free parenchyma, all cancers featured decreased sphingosine-1-phosphate and SMs. qPCR analyses evidenced differential mechanisms leading to these alterations between cancer types, with neuroendocrine carcinomas upregulating SGPL1, but CERT1 being downregulated in adenocarcinomas and squamous cell carcinomas. 2-Hydroxyhexosylceramides (2-hydroxyHexCers) were specifically increased in adenocarcinomas. While UDP-glycosyltransferase 8 (UGT8) transcript levels were increased in all cancer subtypes, fatty acid 2-hydroxylase (FA2H) levels were higher in adenocarcinomas than in squamous and neuroendocrine carcinomas. As a whole, we report differing mechanisms through which all forms of lung cancer achieve low SM and lysosphingolipids. Our results also demonstrate that FA2H upregulation is required for the accumulation of 2-hydroxyHexCers in lung cancers featuring high levels of UGT8.