Background

Noticing the limitations of chemotherapy and the possibility of interrupting the tumor vascular network, there has been an increasing interest in targeting the tumor vasculature and developing agents to disrupt angiogenesis.

Anti-angiogenic drugs, such as bevacizumab, have become a standard treatment option in lung cancer. In spite some clinical success with these inhibitors, disappointing results have been reported with patients being intrinsically refractory to anti-VEGF therapies or, following treatment response, ultimately becoming refractory and showing relapse. Moreover, it has been described that not only the tumor cells, but several host factors and stromal components also play an important role in resistance to bevacizumab (Cascone et al., JCI 2011).

Aims

1) Validate nucleolin as a therapeutic target for a previous developed F3 peptide-targeted pH sensitive liposome containing doxorubicin (Moura et al., BCRT 2012) in human lung cancer models resistant to bevacizumab and assess the potential to overcome anti-angiogenic resistance.

2) Assess nucleolin expression in patients-derived lung cancer.

Experimental design/Results

Aiming at confirming the potential application of a previously developed nanoparticle on lung cancer, cellular association studies were carried with flow cytometry. Cell lines with intrinsic (A549 cells) and acquired (H1975, H441 cells) resistance to bevacizumab were incubated with fluorescently-labeled liposomes, either non-targeted (SLpH) or targeted by a non-specific (SLpHNS) or F3 (SLpHF3) peptide, for 1 h at 37 or 4ºC (temperature not permissive to endocytosis). Results demonstrated a 30 to 170-fold higher extent of association of F3-targeted liposomes by lung cancer cells than the the controls, suggesting a ligand-specific interaction. Improved association and intracellular delivery of encapsulated DXR enabled by F3-targeted liposomes, justified a 9.6-fold increase of DXR cytotoxicity relative to the non-targeted counterparts.

In order to assess the clinical potential of the developed nucleolin-targeted strategy, immunohistochemistry of human specimens derived from lung cancer patients with surgical staged disease was performed aiming at investigating the expression of nucleolin. Results generated so far revealed that nucleolin was highly expressed in different types of cells in the tumor microenvironment of patient-derived lung tumors, in a tumor-specific manner.

Main Conclusion

The generated results render an important indication of the therapeutic potential of the tested nucleolin-targeted strategy against Bevazcizumab-resistant lung cancer.

Acknowledgements

Grants: QREN/FEDER/COMPETE (Ref 23240); PEst-C/SAU/LA0001/2011

Â. Valério-Fernandes is a graduate student from PhD program on Biomedicine and Experimental Biology, Center for Neuroscience and Cell Biology, University of Coimbra (FCT fellowship SFRH/BD/51191/2010)

Citation Format: Ângela Valério-Fernandes, Nuno Fonseca, Vera Moura, Ana Ladeirinha, Teresa Ferreira, Ana Alarcão, Lina Carvalho, Sérgio Simões, João Nuno Moreira. Targeting nucleolin: A potential strategy to overcome stroma-mediated bevacizumab resistance in lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3003. doi:10.1158/1538-7445.AM2014-3003