Silencing of human ferrochelatase causes abundant protoporphyrin-IX accumulation in colon cancer

Hemes and heme proteins are vital components of essentially every cell of virtually every eukaryote organism. Previously, we demonstrated accumulation of the heme precursor protoporphyrin-IX (PpIX) in gastrointestinal tumor tissues. To elucidate the mechanisms of PpIX accumulation by quantitative re...

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Published in:The FASEB journal 2008-02, Vol.22 (2), p.500-509
Main Authors: Kemmner, Wolfgang, Wan, Kayiu, Rüttinger, Steffen, Ebert, Bernd, Macdonald, Rainer, Klamm, Ursula, Moesta, K. Thomas
Format: Article
Language:English
Subjects:
Aminolevulinic Acid - pharmacology
Cell Line, Tumor
Colonic Neoplasms - enzymology
Colonic Neoplasms - genetics
cytoplasmatic red fluorescence
Ferrochelatase - genetics
Ferrochelatase - metabolism
gastrointestinal carcinomas
Gene Expression Regulation, Enzymologic - drug effects
Heme - metabolism
Heme Oxygenase (Decyclizing) - metabolism
Humans
Protoporphyrins - metabolism
RNA, Messenger - genetics
RNA, Small Interfering - genetics
siRNA silencing
Stomach Neoplasms - enzymology
Stomach Neoplasms - genetics
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Summary:Hemes and heme proteins are vital components of essentially every cell of virtually every eukaryote organism. Previously, we demonstrated accumulation of the heme precursor protoporphyrin-IX (PpIX) in gastrointestinal tumor tissues. To elucidate the mechanisms of PpIX accumulation by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we studied expression of the relevant enzymes of the heme synthetic pathway. Here, we describe a significant down-regulation of ferrochelatase (FECH) mRNA expression in gastric, colonic, and rectal carcinomas. Accordingly, in an in vitro model of several carcinoma cell lines, ferrochelatase down-regulation and loss of enzymatic activity corresponded with an enhanced PpIX-dependent fluorescence. Direct detection of PpIX in minute amounts was achieved by a specifically developed pulsed solid-state laser dual delay fluorimetry setup. Silencing of FECH using small interfering RNA (siRNA) technology led to a maximum 50-fold increased PpIX accumulation, imageable by a specifically adapted two-photon microscopy unit. Our results show that in malignant tissue a transcriptional down-regulation of FECH occurs, which causes endogenous PpIX accumulation. Furthermore, accumulation of intracellular PpIX because of FECH siRNA silencing provides a small-molecule-based approach to molecular imaging and molecular therapy--Kemmner, W., Wan, K., Rüttinger, S., Ebert, B., Macdonald, R., Klamm, U., Moesta, K. T. Silencing of human ferrochelatase causes abundant protoporphyrin-IX accumulation in colon cancer.
ISSN:0892-6638
1530-6860
DOI:10.1096/fj.07-8888com