Serum Untargeted UHPLC-HRMS-Based Lipidomics to Discover the Potential Biomarker of Colorectal Advanced Adenoma

Abstract

Background: As a key precancerous lesion, colorectal advanced adenoma (CAA) is closely related to the occurrence and development of colorectal cancer (CRC). Effective identification of CAA-related biomarkers can prevent CRC morbidity and mortality. Lipids, as an important endogenous substance, have been proved to be involved in the occurrence and development of CRC. Lipidomics is an advanced technique that studies lipid metabolism and biomarkers of diseases. However, there are no lipidomics studies based on large serum samples to explore diagnostic biomarkers for CAA.

Methods: An integrated serum lipid profile from 50 normal (NR) and 46 CAA subjects was performed using ultra-high performance liquid chromatography tandem high-resolution mass spectrometry (UHPLC-HRMS). Lipidomic data were acquired for negative and positive ionization modes, respectively. Differential lipids were selected by univariate and multivariate statistics analyses. A receiver operator characteristic curve (ROC) analysis was conducted to evaluate the diagnostic performance of differential lipids.

Results: A total of 53 differential lipids were obtained by combining univariate and multivariate statistical analyses (P < 0.05 and VIP > 1). In addition, 12 differential lipids showed good diagnostic performance (AUC > 0.90) for the discrimination of NR and CAA by receiver operating characteristic curve (ROC) analysis. Of them, the performance of PC 44:5 and PC 35:6e presented the outstanding performance (AUC = 1.00, (95% CI, 1.00-1.00)). Moreover, triglyceride (TAG) had the highest proportion (37.74%) as the major dysregulated lipids in the CAA.

Conclusion: This is the first study that profiled serum lipidomics and explored lipid biomarkers with good diagnostic ability of CAA to contribute to the early prevention of CRC. Twelve differential lipids that effectively discriminate between NR and CAA serve as the potential diagnostic markers of CAA. An obvious perturbation of TAG metabolism could be involved in the CAA formation.

Keywords: UHPLC-HRMS; biomarker; colorectal advanced adenoma; colorectal cancer; serum lipidomics.

Figure 1

The TIC chromatography of normal (NR) and colorectal advanced adenoma (CAA) groups in both ESI modes. (A and B) TIC chromatography of NR in ESI+ and ESI- modes, respectively; (C and D) TIC chromatography of CAA in ESI+ and ESI- modes, respectively.

Figure 2

Multivariate statistical analysis for lipid profile between the NR and CAA groups. (A and B) 3D PCA analysis of the two groups in ESI+ and ESI- modes, respectively; (C and D) 3D OPLS-DA analysis of the two groups in ESI+ and ESI- modes, respectively. R2X[cum] = 0.379 and 0.522, R2Y[cum] = 0.981 and 0.951, Q2[cum] = 0.976 and 0.870; (E and F) Permutation test (200 permutations) corresponding to OPLS-DA model in ESI+ and ESI- modes, respectively.

Figure 3

The proportion of differential lipids between two groups.

Figure 4

Heat map analysis of 53 differential lipids between NR and CAA groups. The color bars represent the log10 value of the ratio for each lipid species and only statistically significant changes are shown (VIP > 1, P < 0.05).

Figure 5

Normalization of the differential lipids between the NR and CAA groups. (A and B) Sample normalization of two groups in ESI+ and ESI- modes, respectively; (C and D) Lipids normalization of two groups in ESI+ and ESI- modes, respectively.

Figure 6

Performance evaluation of differential lipids between NR and CAA groups. (A) PC 35:6e; (B) PC 44:5; (C) Palmitic acid; (D) PC 31:2; (E) PC 37:7; (F) PC 42:9; (G) PC 18:0e; (H) TAG 57:1; (I) Methyl palmitate; (J) LPC 18:0; (K) LPC 17:0; (L) Docosanamide.

Figure 7

The identification of 12 differential lipids with good diagnosis between NR and CAA groups. (A) PC 35:6e; (B) PC 44:5; (C) Palmitic acid; (D) PC 31:2; (E) PC 37:7; (F) PC 42:9; (G) PC 18:0e; (H) TAG 57:1; (I) TAG 57:1; (J) Methyl palmitate; (K) LPC 18:0; (L) LPC 17:0; (M) Docosanamide.

Figure 8

The trend of differential lipids in NR and CAA groups. (A) Docosanamide; (B) LPC 17:0; (C) LPC 18:0; (D) Methyl palmitate; (E) Palmitic Acid; (F) PC 18:0e; (G) PC 31:2; (H) PC 35:6e; (I) PC 37:7; (J) PC 42:9; (K) PC 44:5; (L) TAG 57:1. *Means the significant difference of levels of differential lipid between NR and CAA. The levels of differential lipids were displayed with mean ± SEM.