Molecular profiling of 16K PRL treated tumours by an antibody-array approach

Tumour development is often accompanied by the formation of new blood vessels from existing vasculature. This new intratumoral blood network is driven by the process of angiogenesis, providing the essential nutrients for growth, invasion and metastasis. At the present time, it is well established that inhibitors of angiogenesis prevent the growth and progression of tumours, offering a new therapeutic approach for treatment of cancer. Several studies have already showed that the N-terminal fragment of the human prolactin, 16k-Da PRL, has a potent anti-angiogenic activity. Recently, research groups have demonstrated that the 16k-Da PRL inhibits tumour development in animal models. Despite the fact that several studies leading to improve our knowledge of 16k-Da PRL action were performed, little is known about its role played to prevent tumour growth in vivo. In this study, we first tested the ability of the 16k-Da PRL to inhibit the growth of established HCT116 tumours in nude mice, using an adenovirus approach. As expected, we found that the tumour progression was tightly reduced by the expression of the 16k-Da PRL into the tumours. This antitumour activity was also associated with a slight tumour vascularization.
To discover biomarkers that contribute in 16k-Da PRL tumour suppressive effects, we used one of the most powerful multiplexed detection techonologies: the antibody-microarray proposed by Eurogentec. These protein-chips allow to identify multiple proteins from small amounts of samples within a single experiment. Three independent sets of antibody array from samples of 16k-Da PRL treated tumours and controls were analysed. Experimental and analysis optimisations were applied to ensure the correct interpretation of the fluorescent signals from the antibody arrays. In addition, significant results were confirmed by Western blot analysis. Our study allowed to identify several proteins which could be implicated in the tumour dormancy induced by 16k-Da PRL treatment. Additional analysis will provide important biological information for discovering of the new cancer biomarkers and their relationship with the 16k-Da PRL effects on cancer development.