Crucial considerations for pipelines to validate circulating biomarkers for breast cancer

Comparative Proteomics Analysis of Exosomes Identifies Key Pathways and Protein Markers Related to Breast Cancer Metastasis

Proteomics analysis of circulating exosomes derived from cancer cells represents a promising approach to the elucidation of cell-cell communication and the discovery of putative biomarker candidates for cancer diagnosis and treatment. Nonetheless, the proteome of exosomes derived from cell lines with different metastatic capabilities still warrants further investigation. Here, we present a comprehensive quantitative proteomics investigation of exosomes isolated from immortalized mammary epithelial cells and matched tumor lines with different metastatic potentials in an attempt to discover exosome markers specific to breast cancer (BC) metastasis. A total of 2135 unique proteins were quantified with a high confidence level from 20 isolated exosome samples, including 94 of the TOP 100 exosome markers archived by ExoCarta. Moreover, 348 altered proteins were observed, among which several metastasis-specific markers, including cathepsin W (CATW), magnesium transporter MRS2 (MRS2), syntenin-2 (SDCB2), reticulon-4 (RTN), and UV excision repair protein RAD23 homolog (RAD23B), were also identified. Notably, the abundance of these metastasis-specific markers corresponds well with the overall survival of BC patients in clinical settings. Together, these data provide a valuable dataset for BC exosome proteomics investigation and prominently facilitate the elucidation of the molecular mechanisms underlying primary tumor development and progression.

Circulating Biomarkers in the Management of Breast Cancer

Circulating biomarkers have become a promising modality in the management of many cancers. Similarly, in breast cancer, circulatory biomarkers are useful, non-invasive methods in the diagnosis, prognostication, and evaluation of response to treatment. Invasive surgical biopsies can be potentially replaced by “liquid biopsy,” which involves analysing circulatory biomarkers that may reveal features of primary and metastatic disease. Therefore, providing an insight into the cancer biology can be utilised to monitor treatment response, treatment-induced adaptation and tumour and disease progression through non-invasive means. The objective of this review is to provide an overview of the current status of the circulating biomarkers highlighting their promising impact on the management of patients with breast cancer.

Analysis of the expression profile of serum exosomal lncRNA in breast cancer patients

Background

Breast cancer (BC) is a common tumor that seriously affects women's physical/mental health and even life. BC invasion and metastasis are still the main causes of mortality in BC patients. Exosomal long non-coding RNAs (exo-lncRNA) play an important role in cell communication and can help to understand better the physiological and pathological conditions that result from BC. This study investigates new potential targets and functions of the expression profiles of exo-lncRNAs in BC patients through high-throughput screening and bioinformatics.

Methods

Samples were collected from two BC patients and one healthy subject. The serum exosomal RNAs were subsequently purified, and a library was established for quality inspection and sequencing. The resultant data was compared with the reference data to obtain the differential expression of exo-lncRNAs, and predict the target genes. To obtain the final results, Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to annotate the function and pathway of the differentially expressed genes.

Results

After a comprehensive comparison of the BC patients and healthy subjects, we discovered five up-regulated exo-lncRNAs and six down-regulated exo-lncRNAs of interest. Combining our results with a literature review and screening, we found that VIM-AS1, SNHG8, and ELDR play a role in the progression of BC, with VIM-AS1 predicting 35 target miRNAs; SNHG8 predicting 12 target miRNAs, and ELDR predicting 24 target miRNAs. Target prediction considered that the target gene of VIM-AS1 was VIM and that the target gene of SNHG8 was PRSS12. GO enrichment analysis showed that VIM mainly played a role in cell processes, biological regulation, metabolic regulation, and molecular adhesion, while PRSS12 was enriched through cell metabolism, catalytic activity, and hydrolase activity. KEGG pathway enrichment results also indicated how the VIM protein functions in cancer development through the viral infection signaling pathway and miRNA signaling pathway.

Conclusions

There is a significant difference in the expression profiles of serum exo-lncRNAs between BC patients and healthy individuals. This may be closely related to BC's occurrence, development, and metastasis, and therefore provides a theoretical basis for more in-depth studies into exo-lncRNA.

Exosomes: A Promising Avenue for the Diagnosis of Breast Cancer

Currently, despite the advances in individualized treatment, breast cancer still remains the deadliest form of cancer in women. Diagnostic, prognostic, and therapy-predictive methods are mainly based on the evaluation of tumor tissue samples and are aimed to improve the overall therapeutic level. Therefore, the exploration of a series of circulating biomarkers, which serve as the information source of tumors and could be obtained by peripheral blood samples, represents a high field of interest. Apart from classical biomarkers, exosomes, which are nanovesicles, are emerging as an accessible and efficient source of cell information. The purpose of this review is to summarize the peculiarities of the presently available breast cancer exosomal biomarkers; the review also provides the prediction of a multitude of potential target genes of exosomal microRNAs using 4 databases.

Protein biomarkers for early detection of diseases: The decisive contribution of combinatorial peptide ligand libraries

The present review deals with biomarker discovery, especially in regard to sample treatment via combinatorial peptide ligand libraries, perhaps the only technique at present allowing deep exploration of biological fluids and tissue extracts in search for low- to very-low-abundance proteins, which could possibly mark the onset of most pathologies. Early-stage biomarkers, in fact, might be the only way to detect the beginning of most diseases thus permitting proper intervention and care. The following cancers are reviewed, with lists of potential biomarkers suggested in various reports: hepatocellular carcinoma, ovarian cancer, breast cancer and pancreatic cancer, together with some other interesting applications. Although panels of proteins have been presented, with robust evidence, as potential early-stage biomarkers in these different pathologies, their approval by FDA as novel biomarkers in routine clinical chemistry settings would require plenty of additional work and efforts from the pharma industry. The science environment in universities could simply not afford such heavy monetary investments.

SIGNIFICANCE

After more than 16years of search for novel biomarkers, to be used in a clinical chemistry set-up, via proteomic analysis (mostly in biological fluids) it was felt a critical review was due. In the present report, though, only papers reporting biomarker discovery via combinatorial peptide ligand libraries are listed and assessed, since this methodology seems to be the most advanced one for digging in depth into low-to very-low-abundance proteins, which might represent important biomarkers for the onset of pathologies. In particular, a large survey has been made for the following diseases, since they appear to have a large incidence on human population and/or represent fatal diseases: ovarian cancer, breast cancer, pancreatic cancer and hepatocellular carcinoma.

Early Detection of Pancreatic Cancer-a Defined Future Using Lessons From Other Cancers: A White Paper

The implementation of effective early detection programs has significantly improved treatment, prognosis, and life expectancy in breast, prostate, and colorectal cancers. Early-detection methods need to be developed for pancreatic ductal adenocarcinoma (PDAC), where progress during the past decades has remained slow. Addressing this need, the forum "Early Detection: Lessons Learned from Other Cancers" was held in November 2015 and presented by the Kenner Family Research Fund in partnership with the American Pancreatic Association. Leading experts from breast, prostate, and colorectal cancers described the development of early detection methods in their respective fields. Emerging opportunities for scientific advancement were subsequently identified that hold the greatest promise for the future of early detection in PDAC, including a 4-part strategic map of necessary actionable items. Knowledge from other fields must be applied to achieve large-scale change within the arena of PDAC. A major breakthrough in early detection of PDAC will occur only through a definitive interdisciplinary collaborative effort involving a critical mass of committed academic research institutions, government agencies, industry leaders, and philanthropies.