Increased plasma concentrations of anterior gradient 2 protein are positively associated with ovarian cancer.

Ovarian cancer is often asymptomatic and is diagnosed at an advanced stage with poor survival rates, thus there is an urgent need to develop biomarkers for earlier detection of ovarian cancer. In the present study, we demonstrate for the first time that the previously reported metastasis-inducing protein AGR2 (anterior gradient protein 2) can be detected in the blood of ovarian cancer patients. Using a newly developed ELISA, we show significantly increased concentrations of AGR2 protein in plasma from cancer patients relative to normal controls. Plasma AGR2 concentrations were highest in stages II and III ovarian cancer patients and were similarly elevated in patients with both serous and non-serous tumours. The identification of elevated plasma concentrations of AGR2 may provide a useful biomarker to aid in the discrimination of normal and ovarian cancer patients particularly when used in combination with CA125.

Protein depletion using IgY from chickens immunised with human protein cocktails.

Given that proteomic analysis of complex protein mixtures may be restricted by the presence of highly abundant proteins, sample preparation to remove abundant proteins is essential for the analysis of low abundance proteins. Chickens are effective producers of antibodies (IgY) against mammalian proteins, able to produce large quantities of antibodies that can be recovered by simple non-intrusive extraction of egg yolk. The extraction procedure described uses a modification of the water dilution method (WD) to deplete lipids and lipoproteins followed by sequential precipitation with 31% ammonium sulphate and 12% poly ethylene glycol (PEG) producing IgY antibodies with greater than 95% purity and no loss in immunoreactivity. In the present study, various cocktails of the 12 most abundant human plasma proteins were used as immunogens to produce IgY antibodies. The anti-cocktail IgY antibodies were effectively used to sequentially and selectively immunodeplete abundant proteins from plasma. Also, affinity depletion (e.g., Affi-Gel Blue) was combined with immunodepletion to sequentially deplete abundant proteins from both plasma and urine. The current approach described allows the end user to mix and match sets of IgY cocktails to deplete tailored sets of targeted proteins dependent on their end use application.

The cryptome: a subset of the proteome, comprising cryptic peptides with distinct bioactivities.

There is increasing evidence that proteolytic cleavage gives rise to 'hidden' peptides with bioactivities that are often unpredicted and totally distinct to the parent protein. So far, the liberation of these cryptic peptides, or crypteins, has been shown to be prevalent in proteins associated with endocrine signalling, the extracellular matrix, the complement cascade and milk. A broad spectrum of proteases has been implicated in the generation of natural crypteins that appear to play a role in modulating diverse biological processes, such as angiogenesis, immune function and cell growth. The proteolytic liberation of crypteins with novel activities represents an important mechanism for increasing diversity of protein function and potentially offers new opportunities for protein-based therapeutics.