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. 2024 May 20;104:105163. doi: 10.1016/j.ebiom.2024.105163

Fig. 4.

Fig. 4

Upregulation of ST6GAL1 promotes the spread of prostate cancer to bone. (a) Luciferase tagged PC3 cells (control or ST6GAL1 overexpressing) were injected into BALB/c nude mice via intra cardiac injection. (b) Tumours were monitored over 6 weeks using in vivo bioluminescence imaging. Upregulation of ST6GAL1 significantly increased the number of skeletal tumours formed per mouse (n = 10, unpaired t test, p = 0.006). (c) Ex vivo micro-CT analysis was used to examine tumour induced bone destruction in left tibias and showed that overexpression of ST6GAL1 in PC3 cells significantly enhanced tumour incidence (representative images are shown) (n = 10, Chi-square test, p = 0.04). Scale bar is 1 mm. (d,e) Further bone histomorphometry demonstrated that in mice bearing ST6GAL1 overexpressing tumours there were significantly higher number of osteoclasts per mm medial bone surface (n = 4 unpaired t test, p = 0.0055) but lower number of osteoblasts per mm lateral bone surface in tibias without overt tumours, compared to mice bearing control tumours (n = 5 unpaired t test, p = 0.0452). (f) Sandwich ELISA analysis of CSF1 levels in conditioned media samples from PC3 prostate cancer cells with overexpression of ST6GAL1. CSF1 levels are significantly increased in conditioned media samples from PC3 cells with upregulation of ST6GAL1 (unpaired t test, p = 0.003). (g) Conditioned media samples from DU145 cells overexpressing ST6GAL1 promotes the differentiation of murine primary osteoclast pre-cursors into osteoclasts measured via TRAP staining (unpaired t test, p = 0.0005). Scale bar is 100 μm. (h,i) Primary monocytes from healthy controls were treated with 150 μl of concentrated conditioned media from PC3 cells (control or ST6GAL1 overexpressing) at days 0 and 3 in the presence of 5 μg/ml anti-MCSF or isotype control. Cells were harvested on day 6 and assessed for viability (h) and CD206 expression (i) using flow cytometry. (n = 5, two-way ANOVA, multiple comparisons, (h) cont. vs. OE isotype. p = 0.002. OE isotype vs. OE anti-MCSF p = 0.028. (i) cont. vs OE isotype. p < 0.0001. cont. vs OE isotype. p = 0.0002).