Nitric oxide mediated photo-induced cell death in human malignant cells.

Seyed Mohamed Ali, Malini Olivo

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Photodynamic therapy (PDT) is a therapeutic modality used for the treatment of a variety of solid neoplasms. The principle of PDT is based on the selective uptake of a photosensitizing chemical in tumor tissue/cell followed by irradiation of tumors with visible light. The treatment results in a cascade of oxidative events causing cell death both in vitro and in vivo. Nitric oxide (NO) is a gaseous free radical, which is an important modulator of immune, endocrine and neuronal functions and plays an important role in the induction of apoptosis. Hypericin (HY) is a photosensitizing pigment from Hypericum perforatum that displays phototoxic effects in neoplastic cell lines. Our previous studies have shown HY induced apoptotic cell death in nasopharyngeal carcinoma and other tumor cells. To better understand the oxidative mechanism of apoptosis induced by HY, we hypothesized the role of NO in PDT, which is considered to be involved in a variety of physiological and pathological processes. We first demonstrated the presence of nicotinamide adenine dinucleotide hydrogen phosphate-diaphorase (NADPH-d) reactivity, a potential marker of NO synthesizing (NOS) enzyme both at light (LM) and electron microscopic (EM) level. Immunocytochemistry, using specific antibodies for NOS subtypes (constitutive, NOS I and inducible, NOS II), we observed that both NOS I and NOS II was present in all cell lines. The expression of both NOS I and NOS II was further verified using Western blot analysis as early as 15 min post PDT compared to that of drug-treated non-irradiated and light alone treated control cells. Our observation of NO production and distribution using the DAF-2 method is direct evidence of NO production in PDT-treated cells.

Original languageEnglish
Pages (from-to)751-756
Number of pages6
JournalInternational Journal of Oncology
Volume22
Issue number4
Publication statusPublished - Apr 2003
Externally publishedYes

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Photochemotherapy
Nitric Oxide
Cell Death
Light
Neoplasms
Apoptosis
Physiological Phenomena
Hypericum
Cell Line
Pathologic Processes
NADP
Free Radicals
Hydrogen
Therapeutics
Western Blotting
Immunohistochemistry
Observation
Electrons
Antibodies
Enzymes

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Nitric oxide mediated photo-induced cell death in human malignant cells. / Ali, Seyed Mohamed; Olivo, Malini.

In: International Journal of Oncology, Vol. 22, No. 4, 04.2003, p. 751-756.

Research output: Contribution to journalArticle

Ali, Seyed Mohamed ; Olivo, Malini. / Nitric oxide mediated photo-induced cell death in human malignant cells. In: International Journal of Oncology. 2003 ; Vol. 22, No. 4. pp. 751-756.
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