Integrated analysis of label-free quantitative proteomics and bioinformatics reveal insights into signaling pathways in male breast cancer

Abstract

Male breast cancer (MBC) is a rare malignancy that accounts for about 1.8% of all breast cancer cases. In contrast to the high number of the "omics" studies in breast cancer in women, only recently molecular approaches have been performed in MBC research. High-throughput proteomics based methodologies are promisor strategies to characterize the MBC proteomic signatures and their association with clinico-pathological parameters. In this study, the label-free quantification-mass spectrometry and bioinformatics approaches were applied to analyze the proteomic profiling of a MBC case using the primary breast tumor and the corresponding axillary metastatic lymph nodes and adjacent non-tumor breast tissues. The differentially expressed proteins were identified in the signaling pathways of granzyme B, sirtuins, eIF2, actin cytoskeleton, eNOS, acute phase response and calcium and were connected to the upstream regulators MYC, PI3K SMARCA4 and cancer-related chemical drugs. An additional proteomic comparative analysis was performed with a primary breast tumor of a female patient and revealed an interesting set of proteins, which were mainly involved in cancer biology. Together, our data provide a relevant data source for the MBC research that can help the therapeutic strategies for its management.

Figure 1 -. Venn diagrams of the differentially expressed proteins observed among the comparisons of the MPT x MNT, MLN x MNT and MPT x MLN groups of samples of the male patient. A. Number of all proteins identified as differentially expressed among the groups’ comparison. B. Number of up-regulated and down-regulated proteins (log2-fold change cut-off 1.5) observed among each group comparison. MPT, male-primary breast tumor; MNT, male-non-tumor breast tissue; MLN, male-axillary metastatic lymph node.

Figure 2 -. Protein-protein interactions of the 225 differentially expressed proteins presenting gradual increased/decreased expression levels from MNT to MPT to MLN, predicted by STRING database v. 10.5. The colors of the nodes correspond to different clusters and inter-cluster edges are represented by dashed-lines. MNT, male-non-tumor breast tissue; MPT, male-primary breast tumor; MLN, male-axillary metastatic lymph node.

Figure 3 -. Predicted protein interactive networks of the differentially expressed proteins observed among the MPT and MNT tissue samples, which are related to A. RNA post-transcriptional modification, molecular transport, and RNA trafficking; B. Cell death and survival, cell cycle, and cancer; C. Cardiovascular disease, organismal injury and abnormalities, and cancer. MPT, male-primary breast tumor; MNT, male-non-tumor breast tissue.

Figure 4 -. - Predicted protein interactive network of the differentially expressed proteins observed among the MPT and MLN tissue samples related to cellular development, connective tissue development and function, and tissue development. MPT, male-primary breast tumor; MLN, male-axillary metastatic lymph node.

Figure 5 -. Protein-protein interactions of the 447 differentially expressed proteins between male and female primary breast tumors predicted by STRING database v. 10.5. The colors of the nodes correspond to different clusters and inter-cluster edges are represented by dashed-lines.