Intact glycopeptides identified by LC-MS/MS as biomarkers for response to chemotherapy of locally advanced cervical cancer

Abstract

Objective: For locally advanced cervical cancer (LACC), patients who respond to chemotherapy have a potential survival advantage compared to nonresponsive patients. Thus, it is necessary to explore specific biological markers for the efficacy of chemotherapy, which is beneficial to personalized treatment.

Methods: In the present study, we performed a comprehensive screening of site-specific N-glycopeptides in serum glycoproteins to identify glycopeptide markers for predicting the efficacy of chemotherapy, which is beneficial to personalized treatment. In total, 20 serum samples before and after neoadjuvant chemotherapy (NACT) from 10 LACC patients (NACT response, n=6) and NACT nonresponse, n=4) cases) were analyzed using LC-MS/MS, and 20 sets of mass spectrometry (MS) data were collected using liquid chromatography coupled with high-energy collisional dissociation tandem MS (LC-HCD-MS/MS) for quantitative analysis on the novel software platform, Byos. We also identified differential glycopeptides before and after chemotherapy in chemo-sensitive and chemo-resistant patients.

Results: In the present study, a total of 148 glycoproteins, 496 glycosylation sites and 2279 complete glycopeptides were identified in serum samples of LACC patients. Before and after chemotherapy, there were 13 differentially expressed glycoproteins, 654 differentially expressed glycopeptides and 93 differentially expressed glycosites in the NACT responsive group, whereas there were 18 differentially expressed glycoproteins, 569 differentially expressed glycopeptides and 99 differentially expressed glycosites in the NACT nonresponsive group. After quantitative analysis, 6 of 570 glycopeptides were identified as biomarkers for predicting the sensitivity of neoadjuvant chemotherapy in LACC. The corresponding glycopeptides included MASP1, LUM, ATRN, CO8A, CO8B and CO6. The relative abundances of the six glycopeptides, including MASP1, LUM, ATRN, CO8A, CO8B and CO6, were significantly higher in the NACT-responsive group and were significantly decreased after chemotherapy. High levels of these six glycopeptides may indicate that chemotherapy is effective. Thus, these glycopeptides are expected to serve as biomarkers for predicting the efficacy of neoadjuvant chemotherapy in locally advanced cervical cancer.

Conclusion: The present study revealed that the N-glycopeptide of MASP1, LUM, ATRN, CO8A, CO8B and CO6 may be potential biomarkers for predicting the efficacy of chemotherapy for cervical cancer.

Keywords: LC-MS/MS; biomarker; glycopeptides; locally advanced cervical cancer (LACC); neoadjuvant chemotherapy (NACT).

Figure 1

Workflow of quantitative LC-ESI-MS/MS analysis of intact N-glycopeptide derived from the sera between NACT response and NACT nonresponse patients.

Figure 2

(A) Comparison of the distribution of glycopeptides in different score ranges among the samples between chemotherapy responsive and nonresponsive ones before and after NACT. (B) Column diagram shows the top 2 number of glycopeptides that are distributed between score 300-500.

Figure 3

Venn diagram showing the number of (A) glycoproteins, (B) glycosites, and (C) glycopeptides from the NACT response (red), NACT nonresponse (blue) before treatment and NACT response (green), NACT nonresponse (purple) after treatment samples.

Figure 4

Box plot of relative abundance of N-glycopeptide in serum between NACT responsive (Pre_R) and nonresponsive (Pre_SD) patients before chemotherapy.

Figure 5

Box plot of relative abundance of N-glycopeptide in serum of NACT responsive patients before (Pre_R) and after chemotherapy (Trm_R).

Figure 6

Distribution of glycosylation types of sera glycoproteins from NACT response (A, Pre_R), NACT nonresponse (B, Pre_SD) before treatment and NACT response (C, Trm_R), NACT nonresponse (D, Trm_SD) after treatment. The labels Fuc only, Fuc+NeuAc, NeuAc only and Others refer to the glycopeptides fucosylated only, fucosylated and sialylated, sialylated only and other glycosylated types, respectively.