Research Papers:

Her2 oncogene transformation enhances 5-aminolevulinic acid-mediated protoporphyrin IX production and photodynamic therapy response

Xue Yang, Pratheeba Palasuberniam, Kenneth A. Myers, Chenguang Wang and Bin Chen _

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Oncotarget. 2016; 7:57798-57810. https://doi.org/10.18632/oncotarget.11058

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Xue Yang1, Pratheeba Palasuberniam1, Kenneth A. Myers2, Chenguang Wang3, Bin Chen1

1Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of The Sciences, Philadelphia, Pennsylvania, USA

2Department of Biological Sciences, Misher College of Arts and Sciences, University of The Sciences, Philadelphia, Pennsylvania, USA

3Key Laboratory of Tianjin Radiation and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, China

Correspondence to:

Bin Chen, email: [email protected]

Keywords: human epidermal growth receptor 2 (Her2), aminolevulinic acid (ALA), protoporphyrin IX (PpIX), photodynamic therapy (PDT), heme biosynthesis

Received: April 04, 2016     Accepted: July 19, 2016     Published: August 04, 2016


Enhanced protoporphyrin IX (PpIX) production in tumors derived from the administration of 5-aminolevulinic acid (ALA) enables the use of ALA as a prodrug for photodynamic therapy (PDT) and fluorescence-guided tumor resection. Although ALA has been successfully used in the clinic, the mechanism underlying enhanced ALA-induced PpIX production in tumors is not well understood. Human epidermal growth receptor 2 (Her2, Neu, ErbB2) is a driver oncogene in human cancers, particularly breast cancers. Here we showed that, in addition to activating Her2/Neu cell signaling, inducing epithelial-mesenchymal transition and upregulating glycolytic enzymes, transfection of NeuT (a mutated Her2/Neu) oncogene in MCF10A human breast epithelial cells significantly enhanced ALA-induced PpIX fluorescence by elevating some enzymes involved in PpIX biosynthesis. Furthermore, NeuT-transformed and vector control cells exhibited drastic differences in the intracellular localization of PpIX, either produced endogenously from ALA or applied exogenously. In vector control cells, PpIX displayed a cell contact-dependent membrane localization at high cell densities and increased mitochondrial localization at low cell densities. In contrast, no predominant membrane localization of PpIX was observed in NeuT cells and ALA-induced PpIX showed a consistent mitochondrial localization regardless of cell density. PDT with ALA caused significantly more decrease in cell viability in NeuT cells than in vector cells. Our data demonstrate that NeuT oncogene transformation enhanced ALA-induced PpIX production and altered PpIX intracellular localization, rendering NeuT-transformed cells increased response to ALA-mediated PDT. These results support the use of ALA for imaging and photodynamic targeting Her2/Neu-positive tumors.

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