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SUMMARY:Photodynamic Therapy against Drug-Resistant Cancer Cells
DTSTART;VALUE=DATE-TIME:20260325T084000Z
DTEND;VALUE=DATE-TIME:20260325T090000Z
DTSTAMP;VALUE=DATE-TIME:20260427T052858Z
UID:indico-contribution-10313@events.saip.org.za
DESCRIPTION:Speakers: Paromita Sarbadhikary (University of Johannesburg)\n
 Photodynamic therapy (PDT) has emerged as a promising alternative or adjun
 ct modality for the treatment of breast cancer. PDT relies on the activati
 on of a photosensitizer (PS) by red or near-infrared light\, resulting in 
 the generation of reactive oxygen species (ROS) that induce localized tumo
 r cell damage. Naturally derived tetrapyrrolic PSs have attracted consider
 able interest due to their favor-able photophysical characteristics. Pheop
 horbide-a\, a chlorophyll-derived tetrapyrrole\, demonstrates strong absor
 ption in the red region\, efficient singlet oxygen generation\, preferenti
 al tumor accumula-tion\, and minimal dark toxicity. Although Doxorubicin r
 emains one of the most widely used chemo-therapeutic agents for breast can
 cer treatment\, its prolonged administration is associated with the de-vel
 opment of multidrug resistance\, largely mediated by P-glycoprotein overex
 pression. PDT has shown potential efficacy in overcoming chemoresistant ph
 enotypes. In this study\, we comparatively evaluat-ed the in vitro phototh
 erapeutic efficacy of pheophorbide-a against wild-type MCF-7 breast cancer
  cells and Doxorubicin-resistant MCF-7 (MCF-7/DOX) cells using 660 nm ligh
 t irradiation.\n\nBoth cell subtypes were incubated with varying concentra
 tions of pheophorbide-a for 3 h under dark conditions\, followed by irradi
 ation with a 660 ± 20 nm LED source at a fluence of 1 J/cm² and a power 
 density of 7.08 mW/cm². Cell viability was assessed 24 h post-irradiation
  using the MTT assay. The results demonstrated differential sensitivity be
 tween the two cell lines. Approximately 90% reduc-tion in cell viability w
 as observed in wild-type MCF-7 cells at 1.6 µM pheophorbide-a\, whereas a
  high-er concentration of 2.4 µM was required to induce a comparable leve
 l of cytotoxicity in MCF-7/DOX cells\, indicating moderate resistance in t
 he chemoresistant phenotype. Morphological observations further supported 
 these findings. Wild-type MCF-7 cells exhibited significant cellular shrin
 kage\, membrane disruption\, and extensive cell death following the PDT. I
 n contrast\, MCF-7/DOX cells showed comparatively moderate cytotoxic effec
 ts\, with approximately 30–40% of cells retaining viable morphology at t
 he same treatment dose.\n\nOverall\, pheophorbide-a–mediated PDT demonst
 rated substantial phototoxic activity against both wild-type and Doxorubic
 in-resistant breast cancer cells\, although higher concentrations were nec
 essary to achieve similar efficacy in resistant cells. These findings sugg
 est that plant-derived chlorophyll-based tetrapyrrolic photosensitizers ho
 ld promise as effective PDT agents for targeting multidrug-resistant breas
 t carcinomas. Further mechanistic investigations are required to elucidate
  the underlying cell death signaling pathways and molecular mechanisms at 
 protein\, gene\, and transcriptomic levels to enhance translational applic
 ability.\n\nhttps://events.saip.org.za/event/272/contributions/10313/
LOCATION:
URL:https://events.saip.org.za/event/272/contributions/10313/
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