The Sensitivity of Cancer Cells to Pheophorbide a-Based Photodynamic Therapy Is Enhanced by NRF2 Silencing

Abstract

Photodynamic therapy (PDT) has emerged as an effective treatment for various solid tumors. The transcription factor NRF2 is known to protect against oxidative and electrophilic stress; however, its constitutive activity in cancer confers resistance to anti-cancer drugs. In the present study, we investigated NRF2 signaling as a potential molecular determinant of pheophorbide a (Pba)-based PDT by using NRF2-knockdown breast carcinoma MDA-MB-231 cells. Cells with stable NRF2 knockdown showed enhanced cytotoxicity and apoptotic/necrotic cell death following PDT along with increased levels of singlet oxygen and reactive oxygen species (ROS). A confocal microscopic visualization of fluorogenic Pba demonstrated that NRF2-knockdown cells accumulate more Pba than control cells. A subsequent analysis of the expression of membrane drug transporters showed that the basal expression of BCRP is NRF2-dependent. Among measured drug transporters, the basal expression of breast cancer resistance protein (BCRP; ABCG2) was only diminished by NRF2-knockdown. Furthermore, after incubation with the BCRP specific inhibitor, differential cellular Pba accumulation and ROS in two cell lines were abolished. In addition, NRF2-knockdown cells express low level of peroxiredoxin 3 compared to the control, which implies that diminished mitochondrial ROS defense system can be contributing to PDT sensitization. The role of the NRF2-BCRP pathway in Pba-PDT response was further confirmed in colon carcinoma HT29 cells. Specifically, NRF2 knockdown resulted in enhanced cell death and increased singlet oxygen and ROS levels following PDT through the diminished expression of BCRP. Similarly, PDT-induced ROS generation was substantially increased by treatment with NRF2 shRNA in breast carcinoma MCF-7 cells, colon carcinoma HCT116 cells, renal carcinoma A498 cells, and glioblastoma A172 cells. Taken together, these results indicate that the manipulation of NRF2 can enhance Pba-PDT sensitivity in multiple cancer cells.

The c-MET/PI3K Signaling Is Associated with Cancer Resistance to Doxorubicin and Photodynamic Therapy by Elevating BCRP/ABCG2 Expression

“…A2870 and A2780DR were plated at a density of 5 Â 10 3 cells/well in 96-well plates and after 24 hours, PDT was performed as described in a previous study by Choi et al (2014). Briefly, the cells were treated with Pba (0.025-2.5 mg/ml) for 6 hours, and then the Pba-containing medium was removed.…”

“…Cells were plated at a density of 7 Â 10 3 cells/well on a cover glass slide (SPL Life Sciences, Gyeonggi-do, Korea). After PDT, the cells were washed with phosphate-buffered saline (PBS) and incubated with trans-1(29-methoxyvinyl)pyrene (50 mM) or carboxy-29,79-dichlorofluorescein diacetate (30 mM) at 37°C as previously described (Choi et al, 2014 Measurement of Intracellular Accumulation of Dox and Pba. The cells were plated at a density of 7 Â 10 3 cells on cover glass slides and incubated with Dox or Pba for 6 hours.…”

Expression and clinical significance of Kelch-like epichlorohydrin-associated protein 1 in breast cancer

“…The above studies suggest that the extent of Keap1 expression plays an important role in the prognosis of various tumors. Expression of Nrf2 is increased in breast cancer tissue, and inhibiting the expression of this protein has been shown to suppress tumor development and invasion in in vitro cell culture experiments (Choi et al, 2014;Ryoo et al, 2015). Relevant studies on the expression of Keap1, which inhibits Nrf2, in breast cancer tissue are relatively scarce.…”

Anticancer Activity Of Plant Genus Clerodendrum (Lamiaceae): A Review

“…Lima senyawa yang berhasil diidentifikasi dalam tanaman genus ini yaitu apigenin 7-glucoside, hispidulin, scutellarein-7-O-beta-D-glucuronate, acteoside dan verbascoside menunjukan interaksi dengan protein kanker melalui simulasi penambatan molekul dan berpotensi menimbulkan efek terapi (Gogoi et al 2017 Wang, Zhu, et al 2013;Wang, Xiong, et al 2013;Xu et al 2013 memiliki aktivitas antikanker dari tanaman genus Clerodendrum adalah pheophorbide-related compounds (purpurin 7 dimethyl ester, pheophorbide a, methyl (10S)-hydroxypheophorbide a) (Cheng et al 2001); asam lemak (asam oleat, asam oktadekanoat, asam n-heksadekanoat, dan 6-metil-2-heptanon) (Erukainure et al 2016); asam oleanolik dan clerodinin A (Sannigrahi et al 2012); abitane diterpenoid (trichotomone, trichotomone D, trichotomone F, uncinatone, mandarone E, teuvincenone E, dan trichotomone H) (Wang, Xiong, et al 2013;Wang, Zhu, et al 2013) dan dua senyawa steroid (Xu et al 2013). Mekanisme antikanker beberapa tanaman genus Clerodendrum melalui aktivitas fotositoksisitas (Nakamura et al 1996;Choi et al 2014;Cheng et al 2001), apoptosis, antiproliferatif dan anti-migrasi (Sun et al 2013;Chacko et al 2015). Aktivitas apoptosis ditunjukan oleh peningkatan rasio bax/bcl-2 dan peningkatan ekspresi caspase 9 (Chacko et al 2015).…”

“…Pheophorbide-related compounds yang diisolasi dari tanaman C. calamitosum dan C. cyrtophyllum melalui mekanisme fotositotoksisitas pada sel tumor (Nakamura et al 1996;Choi et al 2014).…”