Objective: The objective of this experiment was to compare the salivary protein profiles of saliva specimens from individuals diagnosed with breast cancer with and without HER2/neu overexpression in an attempt to demonstrate how these profiles may be used to study breast cancer progression. Methods: Pooled (n=10 pooled) stimulated whole saliva specimens from women were analyzed. One pooled specimen was from women diagnosed with Stage IIa (T<sub>2</sub>N<sub>0</sub>M<sub>0</sub>) invasive ductal carcinoma (IDC) without positive HER2/neu receptor status. A second pooled specimen was from women diagnosed with Stage IIa (T<sub>2</sub>N<sub>0</sub>M<sub>0</sub>) IDC with a positive HER2/neu receptor status. Experimentally, saliva from each of the pooled samples was trypsinized and the peptide digests labeled with the appropriate iTRAQ reagent. Labeled peptides from each of the digests were combined and analyzed by reverse phase (C18) capillary chromatography on an LC-MS/MS mass spectrometer equipped with an LC-Packings HPLC. Results: The results yielded 34 up-regulated proteins and 37 down regulated proteins that were differentially expressed between HER2/neu receptor positive HER2/neu receptor negative specimens. Conclusions: This pilot study provides support to the novel idea of using salivary secretions to study breast cancer progression.
Objective: The objective of this study is to determine if LC/MS/MS based isotopic tagging technique is
useful to detect putative breast cancer markers in saliva.
Methods: Six pooled (n=10 subjects per pool) stimulated whole saliva specimens from women were
analyzed. One pooled specimen was from healthy women, another pooled specimen from women
diagnosed with a benign breast tumor and the other four-pooled specimens were from women diagnosed
with carcinoma of the breast. The four cancer specimens were staged 0, I, IIa and IIb (lymph node
involvement). Isotopically tagging proteins in the tumor groups and comparing them to the healthy control
group measured differential expression of proteins. The iTRAQ labels are isobaric and chemically
identical, thus labeled peptides from the different pools have identical elution times and masses. The
relative concentration of identified proteins in each of the mixtures is determined from the intensities of
each of the reporter ions.
Results: The results of the salivary analyses yielded approximately 209 proteins in the saliva specimens.
These proteins were able to distinguish between the healthy control, the benign and the cancer patients.
Additionally, there were proteins able to distinguish between node positive and node negative patients.