A volunteer donating a spit sample during a blood cancer charity. Credit: PA Images/Alamy Stock Photo
Specific salivary proteins and their constituent peptides can help detect triple-negative breast cancer (TNBC)1. The protein and peptide markers have been found to successfully differentiate patients with TNBC from healthy individuals at an early stage of the cancer.
TNBC is the most aggressive subtype of breast cancer. A team at the Indian Institute of Technology Roorkee in Uttarakhand say this non-invasive saliva test is better than existing techniques, such as invasive biopsy and radiological evaluations, which can only detect TNBC once symptoms appear.
The scientists, led by Srinivas Kiran Ambatipudi, collected saliva samples from 20 patients with TNBC and 20 healthy individuals. They identified 39 candidate salivary proteins, of which 9 were upregulated and 30 were downregulated in the TNBC patients.
The team, which included researchers Sudipa Maity and Kuldeep Giri, discovered differential expression of three salivary proteins – lipocalin-1 (LCN1), submaxillary androgen-regulated protein 3B (SMR3B) and plastin-2 (LCP1) in the patients and in people without cancer. They found increased expression of LCN1 and SMR3B in the samples from patients with TNBC. These proteins are involved in pathways that aid tumour growth and invasion, giving rise to metastasis.
Next, the researchers isolated peptides from the three proteins. They took two peptides from each of the proteins. The combined predictive power of five peptides gave a better diagnostic performance, with 80% sensitivity and 95% specificity in the TNBC patients.
If the efficacy of the peptide markers is validated in a large number of patients, they could be used to devise a powerful diagnostic test for TNBC, the researchers say.
