Investigating the Function of Human Jumping Translocation Breakpoint Protein (hJTB) and Its Interacting Partners through In-Solution Proteomics of MCF7 Cells

Abstract

Human jumping translocation breakpoint (hJTB) gene is located on chromosome 1q21 and is involved in unbalanced translocation in many types of cancer. JTB protein is ubiquitously present in normal cells but it is found to be overexpressed or downregulated in various types of cancer cells, where this protein and its isoforms promote mitochondrial dysfunction, resistance to apoptosis, genomic instability, proliferation, invasion and metastasis. Hence, JTB could be a tumor biomarker for different types of cancer, such as breast cancer (BC), and could be used as a drug target for therapy. However, the functions of the protein or the pathways through which it increases cell proliferation and invasiveness of cancer cells are not well-known. Therefore, we aim to investigate the functions of JTB by using in-solution digestion-based cellular proteomics of control and upregulated and downregulated JTB protein in MCF7 breast cancer cell line, taking account that in-solution digestion-based proteomics experiments are complementary to the initial in-gel based ones. Proteomics analysis allows investigation of protein dysregulation patterns that indicate the function of the protein and its interacting partners, as well as the pathways and biological processes through which it functions. We concluded that JTB dysregulation increases the epithelial-mesenchymal transition (EMT) potential and cell proliferation, harnessing cytoskeleton organization, apical junctional complex, metabolic reprogramming, and cellular proteostasis. Deregulated JTB expression was found to be associated with several proteins involved in mitochondrial organization and function, oxidative stress (OS), apoptosis, and interferon alpha and gamma signaling. Consistent and complementary to our previous results emerged by using in-gel based proteomics of transfected MCF7 cells, JTB-related proteins that are overexpressed in this experiment suggest the development of a more aggressive phenotype and behavior for this luminal type A non-invasive/poor-invasive human BC cell line that does not usually migrate or invade compared with the highly metastatic MDA-MB-231 cells. This more aggressive phenotype of MCF7 cells related to JTB dysregulation and detected by both in-gel and in-solution proteomics could be promoted by synergistic upregulation of EMT, Mitotic spindle and Fatty acid metabolism pathways. However, in both JTB dysregulated conditions, several downregulated JTB-interacting proteins predominantly sustain antitumor activities, attenuating some of the aggressive phenotypical and behavioral traits promoted by the overexpressed JTB-related partners.

Omics-Based Investigations of Breast Cancer

“…Proteomics approaches based on the LC-MS/MS strategy have been used for the proteomic analyses of BCCL exosomes and have revealed disease patterns and potential biomarkers [ 201 ], as well as being used for examining BCCL-conditioned media that has shown a significant enrichment in the secreted proteins involved in BC development in comparison the corresponding cell lysates [ 319 ]. Several of our studies have investigated the effects of the overexpression [ 320 ] and downregulation [ 321 , 322 ] of the jumping translocation breakpoint (JTB) protein and its interacting partners for potential use as biomarker in BC, using an LC-MS/MS approach combined with in-gel [ 320 , 321 ], as well as the in-solution proteomics of MCF7 cells [ 322 ]. Three BCCLs, MCF10A (non-malignant), MCF7 (estrogen- and progesterone-receptor-positive, metastatic), and MDA-MB-231, have been investigated using LC-MS/MS for a phosphoproteomics-based analysis of BC-derived small EVs, in order to emphasize the disease-specific phosphorylated metabolic enzymes [ 323 ].…”

Recent Contributions of Mass Spectrometry-Based “Omics” in the Studies of Breast Cancer

“…Effects of downregulation of a specific protein in cancer cell lines and resultant proteome and interactome characterizations offer an attractive way toward identification of global changes affecting cellular behavior. Such alterations are regularly identified through strategic experimentations involving MS. 161 Knock down of EZH2 reverses tamoxifen (TMX) resistance in cell lines by affecting levels of proteins like CD44, Annexin A2, nucleosome assembly protein 1, and lamin A/C. 121 Matrix metalloproteinase-11 (MMP-11), an endopeptidase that degrades ECM, facilitates cancer development and metastasis.…”

“…Cell lines are probed for drug-resistant proteomes, and potential drug responsive proteins are identified . Specific queries of protein expressions in BC cells are to be used as potential biomarkers for cancer tissues . Reports of cross “omic” studies are integrated.…”

“…11 Specific queries of protein expressions in BC cells are to be used as potential biomarkers for cancer tissues. 58 Reports of cross "omic" studies are integrated. MS-based "omic" studies that were performed for categorizing differences in "omic" panels are comprehensively reviewed by Rossi (2022).…”

Deciphering the influence of centrosome-related genes on osteosarcoma to develop a prognostic signature

“…The presence and role of JTB in cancer are linked to the emergence, progression, and spread of different malignant tumors[36].Several research studies indicate that the amount of JTB expression is notably increased in speci c types of cancer, including breast cancer, liver cancer, and colon cancer[37][38][39].Furthermore, JTB is also implicated in biological processes like cell proliferation, invasion, and cancer cell metastasis, rendering it a promising target for therapy.According to recent research, JTB has been found to impact the ability of immune cells to function, leading to tumor immune escape. This has made it a highly discussed subject in the eld of cancer immunotherapy[40].Nevertheless, the impact of JTB on osteosarcoma remains unexplored.Based on our above research, we believe that paclitaxel can affect the biological activity of JTB by binding to the protein it encodes.JTB has a twofold impact on tumor cell division and the regulation of immune cells, particularly immune cells, consequently in uencing the prognosis of patients.…”