Serum Metabolomic Profiling for OSCC Stages
We also investigated whether serum metabolomic pattern differences exist
not only between HC and OSCC but also among different stages
(from
stage T1 to stage T4). The OPLS-DA model visualized the distribution of
the OSCC cases in the development cohort (Fig. 4A ). It can be
seen the OSCC at T1 and T2 stages can be ideally separated from these
samples at the T3 and T4 stages. Unfortunately, there was no obvious
separation between T1 and T2 or T3 and T4. The variables that made a
high contribution to this T1/T2 and T3/T4 separation were searched
according to their variable importance on projection (VIP) values. The
variables with VIPs large than 1.5 were picked (Table S8 ).
After removing redundant ions, the top 50 metabolites were annotated and
their relative contents in serum were displayed in a heatmap. It was
worth noting that 4 out of the top 10 metabolites discovered in the
univariate analysis (DG(34:2), oleamide, LPC(20:4), and
nonanoyl carnitine) also
contributed to this T1/T2 and T3/T4 stages discrimination (Fig.
4B ). As shown in Fig. 4C, the relative contents of these
metabolites in the OSCC group (T1-T4) were completely different from
those in the HC group. Furthermore, they also showed increasing or
decreasing trends from T1 to T4. Unfortunately, none of these top 50
metabolites showed statistical significance among the four stages by the
analysis of one-way variance (ANOVA).