Activation of S1PR2 upregulates tumoral DPD by promoting the interaction
of TWIST1 with the JMJD3-RNA Pol II complex bound to the DPYD promoter
Abstract
Background and Purpose: Dihydropyrimidine dehydrogenase (DPD) is a major
determinant of 5-FU resistance in cancers. DPD catalyzes 5-FU into FBAL
(α-fluoro-β-alanine) to lower intracellular 5-FU level. We aimed to
investigate mechanism and clinical significance of FBAL-stimulated
sphingosine 1-phosphate receptor 2 (S1PR2) in upregulation of DPD in
colonic cancer. Experimental Approach: Cancer cells transfected or
silenced S1PR2 were exposed to FBAL for analyzed S1PR2 and DPD levels.
Luciferase reporter assay analyzed S1PR2-activated TWIST1 binding to
DPYD promoter. Co-IP assay analyzed TWIST1 interaction with JMJD3-RNA
Pol II complex binding to DPYD promoter. HT-29sh-S1PR2 or SW480TgS1PR2
cells xenografted nude mice were used to evaluate clinical significance
of S1PR2-upregulated tumoral DPD. Key Results: Activation of S1PR2
upregulated DPD in colonic cancer cells and human fresh cancer
specimens. FBAL was first time identified as an etiological stimulator
of S1PR2 activation. The FBAL-stimulated S1PR2 increased TWIST1 binding
to DPYD promoter and interacting with JMJD3-RNA Pol II complex,
enhancing H3K27me3-enriched DPYD transcription elongation. Transfection
of S1PR2 in SW480TgS1PR2 xenograft contributed 5-FU resistance by
45.14%, and silence of S1PR2 improved 5-FU sensitivity by 62.12% in
HT-29sh-S1PR2 xenograft. S1PR2 inhibitor JTE013 prevented the
FBAL-stimulated S1PR2’s effects in upregulating DPD. Cancer cells with
high S1PR2 are more resistant to 5-FU, strongly suggesting clinical
significance that combination use of S1PR2 inhibitors may be the
appropriate 5-FU-based regimens of colonic cancers. Conclusions and
Implications: The FBAL-stimulated S1PR2 increased TWIST1 binding to DPYD
promoter and interacting with JMJD3-RNA Pol II, enhancing the
H3K27me3-enriched DPYD transcription elongation.