Studying the salivary proteins may offer an easy alternative for screening cancer patients

Researchers at the Indian Institute of Technology (IIT) Roorkee have taken the first step to identify certain proteins found in saliva that can be used as potential biomarkers indicative of breast and ovarian cancer metastasis. The composition and expression of salivary gland-derived proteins are altered in people with breast and ovarian cancer. So studying the salivary proteins may offer an easy alternative for screening cancer patients.

Using 10 samples each of healthy and stage IV breast and ovarian cancer patients, and from ovarian cancer patients who have undergone at least three cycles of chemotherapy (with paclitaxel and carboplatin) the researchers were able to identify 409 unique proteins.

“The proteins were selected only when we were able to identify at least two different peptides that are unique. And to eliminate false positives, we used higher (99%) statistical significance,” says Dr. Kiran Ambatipudi from the institute’s Department of Biotechnology and corresponding author of a paper published in the journal FASEB BioAdvances.

On comparing with healthy subjects, the team was able to identify 13 proteins that were unique to breast cancer patients; healthy subjects had 18 unique proteins. Similarly, comparing breast and ovarian cancer patients, they found 20 and five proteins unique to breast and ovarian patients, respectively. Ovarian cancer patients who have not undergone chemotherapy had 24 unique proteins compared with 17 proteins that were found only in ovarian cancer patients who have undergone at least three cycles of chemotherapy.

“The unique proteins that were found in breast and ovarian cancer patients were associated with progression of metastasis,” says Kuldeep Giri from the Department of Biotechnology at IIT Roorkee and first author of the paper. There are also proteins that are 15-20 times differentially expressed in both types of cancers. “These proteins may be playing a critical role in metastasis. We don’t know yet,” says Dr. Ambatipudi.

In those who have undergone at least three cycles of chemotherapy, the researchers were able to indentify nine proteins indicating that salivary proteins could indicate patients’ responsiveness to chemotherapy.

Based on studies done by other groups, the team has zeroed in on six proteins, which would be taken up for detailed functional analysis and validation through in vitro and in vivo studies.

“We also plan to identify and validate the exclusive and differentially expressed proteins in a large patient sample for the development of salivary proteins as potential biomarkers for early detection of breast and ovarian cancers as well as their progression,” says Dr. Ambatipudi.