Comprehensive proteome and phosphoproteome analysis reveals the protein characterization of invasive ductal and lobular carcinoma with specific molecular subgroup

Abstract

Background Breast cancer is one of the most frequently occurring malignant cancers worldwide. Invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC) are the two most common histological subtypes of breast cancer. The prognosis and survival of the two subtypes were significantly different even with specific molecular subgroup. In this study, we aimed to deeply explore molecular characteristics and the relationship between IDC and ILC subtypes in same molecular subgroup of breast cancer using comprehensive proteomics and phosphoproteomics analysis. Methods Cancer tissues and noncancerous adjacent tissues (NATs) with the luminal subtype (ER- and PR-positive, HER2-negative) were obtained from paired IDC and ILC patients respectively. Label-free quantitative proteomics and phosphoproteomics methods were used to detect differentially expressed proteins and the phosphorylation status between 10 paired breast cancer and NATs. Then, bioinformatics analysis was performed to explore the difference between IDC and ILC subtypes, including the difference in protein expression levels and the degree of phosphorylation. Meanwhile, Kinase-Substrate Enrichment Analysis (KSEA) revealed the activation difference of kinases and their substrates between IDC and ILC. Results A total of 5,044 high-confidence proteins and 3,808 phosphoproteins were identified from breast cancer tissues. The protein phosphorylation level in ILC tissues was higher than that in IDC tissues. From the quantitative analysis of 1259 proteins and 560 phosphoproteins with high patient coverage, Histone H1.10, Complement C4-B and Crk-like protein were found to be significantly differentially expressed in the two subtype tissues from the proteomics analysis. Moreover, the differences in protein expression of Septin-2, Septin-9, Heterogeneous nuclear ribonucleoprotein A1 and Kinectin and their phosphorylation clearly distinguished IDC from ILC. In addition, differentially expressed proteins and differentially expressed phosphoproteins in IDC were primarily related to energy metabolism and MAPK pathway, while ILC subtypes were more closely involved in the AMPK and p53/p21 pathways. Furthermore, the kinomes from IDC were primarily significantly activated in the CMGC (Cyclin-dependent kinases, Mitogen-activated protein kinases, Glycogen synthase kinases and CDK-like kinases) groups. Conclusions Our research provides insights into the molecular characterization of IDC and ILC and contributes to discovering novel targets for further drug development and targeted treatment.