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. 2022 Apr 16;34:100430. doi: 10.1016/j.jbo.2022.100430

Fig. 4.

Fig. 4

The C3-H2 peak of 2-HG is detectable at 1.84 ppm in the in vivo MR spectrum of IDH1-mutant chondrosarcoma. A. Experimental schematic of the in vivo MRS study. NOD-SCID mice were transplanted subcutaneously with JJ012 (IDH1R132G) (n = 8) or NDCS-1 (IDH-WT) cells (n = 4), and continuously fed DS-1001b mixed with sterilized pellet food for 3 weeks after confirmation of tumor engraftment. B. Representative MR images of JJ012 and NDCS-1 tumors. Squares of 3 × 3 mm2 indicate voxels of interest (VOIs) in MRS measurements. The pictures on the left and right are representative transverse slices of an IDH-mutant (JJ012) and an IDH-WT (NDCS-1) tumor. Note that the IDH-WT tumor shows heterogeneity in the tumor interior and profoundly low signal areas suggestive of intratumoral hemorrhage (arrowhead). C. In vivo MR spectrum (upper) of a representative case of IDH1-mutant chondrosarcoma xenograft (JJ012). NMR spectra of the tumor extract with 10-Hz line broadening (middle) and 0.3-Hz line broadening (bottom). Arrows indicate chemical shift positions of each 2-HG peak: C3-H2 at 1.84, C3′-H2 at 1.99 ppm, C4-H2 at 2.25 ppm, and C2-H at 4.02 ppm. On the in vivo MR spectrum, peaks at 1.99 and 4.02 ppm are obscured because they produce composite peaks with adjacent metabolites. In addition, the C4-H2 peak likely overlaps with the –CH2-COO resonance of lipid at 2.25 ppm, which is detected in the in vivo MR spectrum but not in the NMR spectra. D. Overlays of representative MR spectra of IDH1-mutant (black) and IDH-WT (gray) tumors indicate that the tiny signal at 1.84 ppm, corresponding to the C3-H2 peak of 2-HG, is seen only in the IDH1-mutant tumor (arrow). The vertical scales of the two MR spectra were adjusted to ensure that the heights of the N(CH3) peaks at 3.03 ppm were equivalent. E. MR spectra of DS-1001b– and vehicle-treated JJ012 tumors. Note that the tiny signals at 1.84 ppm, corresponding to the C3-H2 peak of 2-HG (arrows), are detectable in vehicle-treated but not DS-1001b–treated tumors. The vertical scales of the four MR spectra were adjusted to ensure that the heights of the N(CH3) peaks at 3.03 ppm were equivalent. F. Scatter plots showing intratumoral 2-HG levels in NDCS-1 and JJ012 (vehicle- and DS-1001b–treated) tumors.