PRM (Parallel Reaction Monitoring) technology, a new generation of protein targeting assays and histological validation technologies, is a perfect alternative to antibody-based Western blot and ELISA. As an excellent targeting technology, PRM is being used in a wide range of research areas.
Case 1. PRM technology facilitates clinical diagnostic marker screening (1)
Cystic lesions of the pancreas are common imaging episodes, and more than half of them may be precursors of pancreatic cancer. Therefore, an accurate differential diagnosis is crucial for precise patient management. However, currently available diagnostic methods cannot reliably distinguish between precancerous and malignant pancreatic cystic lesions. To address this problem, a team of researchers from the University of Gothenburg performed a high-precision marker analysis using proteomic exploration + PRM-targeted assays.
Using a untargeted quantitative proteomics approach, the researchers screened eight candidate markers in the discovery cohort for differentiating between potentially malignant and highly atypical hyperplasia/cancer. Subsequently, 30 peptides of the eight candidate proteins were analyzed for absolute quantification using PRM technology in both the training cohort and the validation cohort. Results from the training cohort were used to validate the pre-post histology data and results from the validation cohort were used for prospective evaluation.
The results showed that peptides of mucin-5AC and mucin-2 were the best marker panel for detecting malignant potential and were able to differentiate between precancerous/malignant and benign lesions in the validation cohort with an accuracy of 97%, compared with 61% accuracy for the standard analysis method CEA immunoassay and 84% accuracy for cytological analysis. When combined with mucin-5AC protein and prostate stem cell antigen (PSCA) markers, the degree of malignancy of pancreatic cancer could be accurately identified with an accuracy of 96%, which was superior to carcinoembryonic antigen testing and cytology.
Therefore, quantification of mucin-5AC, mucin-2 and PSCA, three pancreatic cystic fluid biomarkers, using PRM technology can help physicians to accurately determine cystic pancreatic cancer and precursor lesions. This study lays the foundation for subsequent exploration of whether PRM technology can be applied for timely diagnosis, successful intervention and prevention of cancer.
Case 2. PRM-based targeted proteomics identified inhibitors of melanoma metastasis by targeting heat shock proteins. (2)
Heat shock proteins are a class of molecular chaperone proteins that are involved in protein folding, cell cycle regulation, cell protection and other functions during stress. The comprehensive analysis of heat shock proteins will help in drug development and cancer treatment.
Heat shock proteins are molecular chaperone proteins involved in protein folding. In this study, the human heat shock proteome was targeted and quantified by PRM technology. The differential expression of heat shock proteins in three pairs of primary/metastatic melanoma cell lines was subsequently assessed by PRM technology. Approximately 45 heat shock proteins could be quantified in each cell line pair, and the quantification results showed that DNAJB4 was downregulated in three metastatic melanoma cell lines. TCGA data indicated that low expression of DNAJB4 predicted a poor prognosis for melanoma patients. Moreover, DNAJB4 was found to inhibit the invasion of cultured melanoma cells by reducing the expression and activity of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9). In this study, the human heat shock proteome was established for the first time by targeted proteomics and DNAJB4 was found to be an inhibitor of melanoma metastasis.
In this study, the authors developed the first PRM-based targeted quantitative proteomics approach for the comprehensive analysis of the human cellular heat shock proteome. the PRM library contains 57 heat shock proteins, representing approximately 70% of the human heat shock proteome. The results showed that the method has higher high throughput and higher sensitivity than the birdshot proteomic method.
The targeted proteomics approach identified new potential inhibitors of melanoma metastasis, which provides an important basis for understanding the etiology of melanoma progression.
References
- Jabbar, Karolina S., et al. "Highly accurate identification of cystic precursor lesions of pancreatic cancer through targeted mass spectrometry: a phase IIc diagnostic study." Journal of Clinical Oncology 36.4 (2018): 367.
- Miao, Weili, Lin Li, and Yinsheng Wang. "A targeted proteomic approach for heat shock proteins reveals DNAJB4 as a suppressor for melanoma metastasis." Analytical chemistry 90.11 (2018): 6835-6842.
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