title: Cellular uptake of 9-hydroxypheophorbide-α and its photoactivation to induce ER stress-related apoptosis in human cervical cancer cells.
abstract: The 9-hydroxypheophorbide-α (9-HPbD) is a chlorophyll derivative and was found to be very effective for photodynamic therapy of tumor cells. The current study investigates uptake, retention, and intracellular localization of 9-HPbD by HeLa, human cervical cancer cells via fluorescence spectrophotometry and confocal laser scanning microscopy, and its photodynamic effect against human cervical carcinoma cell. HeLa cells exposed to 9-HPbD exhibited a linear uptake of photosensitizer during the first 12 h, and after removal of 9-HPbD, cell fluorescence was observed to decrease gradually over the next 12 h. Cells treated with 9-HPbD and stained with a panel of organelle-specific fluorescence probes (MitoTracker, LysoTracker, and ER-Tracker) revealed an intracellular fluorescence distribution restricted to cytoplasmic compartments with no detectable fluorescence in the nucleus. The 9-HPbD showed cytotoxicity effect against HeLa cells in 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Endoplasmic reticulum (ER) disruption and cellular calcium dynamics also showed a photoactivation followed by cell death. The apoptotic effect of 9-HPbD was confirmed by caspase 3 activity study and immunofluorescence study of caspase 12. Morphological observation through the transmission electron microscopy and scanning electron microscopy also confirmed that 9-HPbD can induce apoptosis in HeLa cells. Therefore, it can be concluded that maximum uptake and clearance time of 9-HPbD was 12 h with endoplasmic reticulum as the major organelle site in cellular uptake, and 9-HPbD can induce apoptosis in HeLa cells through ER stress-related pathways via activation of caspase 12.
authors: Medical Laser Research Center, College of Medicine, Dankook University, Cheonan, Chungnam, South Korea.
authors: Jin Chul
authors: JC
authors: Ahn
authors: Raktim
authors: R
authors: Biswas
authors: Jeong Hwan
authors: JH
authors: Moon
authors: Phil Sang
authors: PS
authors: Chung
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism; D053454:Caspase 12 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000648:ultrastructure; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D005260:Female; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*
chemical_list: C491791:9-hydroxypheophorbide alpha; D017319:Photosensitizing Agents; D002734:Chlorophyll; C506444:CASP12 protein, human; C505407:CASP3 protein, human; D053454:Caspase 12; D053148:Caspase 3; D002118:Calcium
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