Fig 2: Glycolysis inhibitor 2-DG abolishes the effect of DCXR overexpression on proliferation and glycolytic metabolism of human MDA-MB-231 cells. (A) oeDCXR-transduced MDA-MB-231 breast cancer cells exhibited decreased cell proliferation in the presence of 2-DG. (B) 2-DG abolished the effect of oeDCXR on promoting the cycle of MDS-MB-231 cells. 2-DG exposure inhibited the production of (C) ATP and (D) LD in oeNC and oeDCXR-transduced cells. (E) ECAR (mpH/min) of oeDCXR-transduced cells was suppressed in the presence of the inhibitor 2-DG. **P<0.01, ***P<0.001 vs. vehicle; ##P<0.01, ###P<0.001 vs. Vehicle + oeDCXR. 2-DG, 2-deoxy-D-glucose; DCXR, dicarbonyl/L-xylulose reductase; ECAR, extracellular acidification rate; LD, lactate dehydrogenase; NC, negative control; OD, optical density; oe, overexpression.

Fig 3: DCXR is upregulated and associated with cancer progression in human breast cancer tissue. (A) DCXR expression levels were increased in 1,104 human breast cancer compared with 113 paracancerous samples in TCGA database. (B) DCXR mRNA expression levels were determined using reverse transcription-quantitative PCR in 30 pairs of breast cancer and paracancerous tissue. The patients were grouped into low- and high-expression populations according to the immunohistochemistry score; 0–3 was defined as low protein expression and 4–9 was defined as high protein expression of DCXR. ***P<0.001. (C) DCXR protein levels were examined using immunohistochemical staining assay in paracancerous and breast cancer tissue with low and high mRNA levels (scale bar, 200 µm). (D) High expression of DCXR was associated with poor prognosis in patients with breast cancer. (E) Univariate and (F) multivariate risk factor analysis of DCXR expression, tumor size, tumor stage, AJCC stage and distant metastasis with breast cancer. AJCC, American Joint Committee on Cancer; DCXR, dicarbonyl/L-xylulose reductase; TCGA, The Cancer Genome Atlas.

Fig 4: DCXR silencing suppresses proliferation, arrests the cell cycle and decreases glycolysis activity of human breast cancer cells. Bioinformatics analysis indicated that DCXR was enriched in (A) ‘glycolysis’ and (B) ‘cell cycle’ in breast cancer. Proliferation of (C) ZR751 and (D) BT-474 cells was suppressed following transduction with shDCXR-1 and shDCXR-2. Knockdown of DCXR arrested cells in G0/G1 phase in (E) ZR751 and (F) BT-474 cells. DCXR silencing decreased production of (G) ATP and (H) LD in ZR751 and BT-474 cells. Both shDCXR-1 and shDCXR-2 suppressed ECAR (mpH/min) in (I) ZR751 and (J) BT-474 cells. *P<0.05, **P<0.01, ***P<0.001 vs. shNC. ES, enrichment Score; NES, normalized enrichment score; 2-DG, 2-deoxy-D-glucose; DCXR, dicarbonyl/L-xylulose reductase; ECAR, extracellular acidification rate; LD, lactate dehydrogenase; NC, negative control; OD, optical density; sh, short hairpin.

Fig 5: DCXR silencing suppresses tumorigenicity of human breast cancer cells in a mouse tumor model in vivo. Nude mice were subcutaneously injected with ZR751 cells transduced with shDCXR or shNC. Following injection, tumor (A) volume and (B) weight were measured; *P<0.05, ***P<0.001 vs. shNC. (C) After 33 days of tumor growth, xenografts were removed for Ki-67 immunohistochemical staining to evaluate cell proliferation (scale bar, 200 µm). DCXR, dicarbonyl/L-xylulose reductase; NC, negative control; sh, short hairpin RNA.