Inhibition of cell growth induced by photosensitizer PP(Arg)2-mediated photodynamic therapy in human breast and prostate cell lines. Part I

Novel carbohydrate-substituted metallo-porphyrazine comparison for cancer tissue-type specificity during PDT

A longstanding obstacle to cancer eradication centers on the heterogeneous nature of the tissue that manifests it. Variations between cancer cell resistance profiles often result in a survival percentage following classic therapeutics. As an alternative, photodynamic therapys' (PDT) unique non-specific cell damage mechanism and high degree of application control enables it to potentially deliver an efficient treatment regime to a broad range of heterogeneous tissue types thereby overcoming individual resistance profiles. This study follows on from previous design, characterization and solubility analyses of three novel carbohydrate-ligated zinc-porphyrazine (Zn(II)Pz) derivatives. Here we report on their PDT application potential in the treatment of five common cancer tissue types in vitro. Following analyses of metabolic homeostasis, toxicity and cell death induction, overall Zn(II)Pz-PDT proved comparably efficient between all cancer tissue populations. Differential localization patterns of Zn(II)Pz derivatives between cell types did not appear to influence the overall PDT effect. All cell types exhibited significant disruptions to mitochondrial activity and associated ATP production levels. Toxicity and chromatin structure profiles revealed indiscernible patterns of damage between Zn(II)Pz derivatives and cell type. The subtle differences observed between individual Zn(II)Pz derivatives is most likely due to a combination of carbohydrate moiety characteristics on energy transfer processes and associated dosage optimization requirements per tissue type. Collectively, this indicates that resistance profiles are negated to a significant extent by Zn(II)Pz-PDT making these derivatives attractive candidates for PDT applications across multiple tissue types and subtypes.

Palmatine hydrochloride mediated photodynamic inactivation of breast cancer MCF-7 cells: Effectiveness and mechanism of action

Breast cancer is one of the commonest malignant tumors threatening to women. The present study aims to investigate the effect of photodynamic action of palmatine hydrochloride (PaH), a naturally occurring photosensitizer isolated from traditional Chinese medicine (TCM), on apoptosis of breast cancer cells. Firstly, cellular uptake of PaH in MCF-7 cells was measured and the cytotoxicity of PaH itself on breast cancer MCF-7 cells was estimated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Subcellular localization of PaH in MCF-7 cells was observed using confocal laser scanning microscopy (CLSM). For photodynamic treatment, MCF-7 cells were incubated with PaH and then irradiated by visible light (470nm) from a LED light source. Photocytotoxicity was investigated 24h after photodynamic treatment using MTT assay. Cell apoptosis was analyzed 18h after photodynamic treatment using flow cytometry with Annexin V/PI staining. Nuclear was stained using Hoechst 33342 and observed under a fluorescence microscope. Intracellular production of reactive oxygen species (ROS) was studied by measuring the fluorescence of 2, 7-dichlorofluorescein (DCF) using a flow cytometry. Results showed that PaH treatment alone had no or minimum cytotoxicity to MCF-7 cells after incubation for 24h in the dark. After incubation for 40min, the cellular uptake of PaH reached to the maximum, and PaH mainly located in mitochondria and endoplasmic reticulum of MCF-7 cells. Photodynamic treatment of PaH demonstrated a significant photocytotoxicity on MCF-7 cells, induced remarkable cell apoptosis and significantly increased intracellular ROS level. Our findings demonstrated that PaH as a naturally occurring photosensitizer induced cell apoptosis and significantly killed MCF-7 cells.

Fabrication of Fe-Al Intermetallic Foams via Organic Compounds Assisted Sintering

The influence of the addition of organic compounds, such as palmitic acid and cholesteryl myristate, on the porous structure of Fe-Al intermetallics formation has been investigated in detail in this paper. It was found that additives have a significant effect on the final porosity of the obtained sinters. Formed gaseous products from combustion play the role of the foaming agent during Fe-Al intermetallic alloy sintering. The influence of these additives is also clearly noticeable in chemical composition changes of the final products through the increase of carbon content in the porous structure. This is attributed to the thermal decomposition, namely combustion, of the organic additives.

Apoptosis of breast cancer cells induced by hypocrellin B under light-emitting diode irradiation

OBJECTIVES

Breast cancer is a common disease which threatens the life of women. To explore an alternative modality for combating breast cancer, a light-emitting diode (LED) that activates hypocrellin B was used in the present study to investigate apoptosis induction in breast cancer MDA-MB-231 cells.

MATERIALS AND METHODS

Photocytotoxicity was investigated 24h after photodynamic treatment of hypocrellin B using MTT reduction assay and light microscopy. Apoptosis was observed 6h after photodynamic treatment using flow cytometry with Annexin V/PI staining as well as fluorescent microscopy with Hoechst33258 staining. The ultrastructure of the treated cells was observed using transmission electron microscopy (TEM).

RESULTS

Hypocrellin B-induced photocytotoxicity in MDA-MB-231 cells exhibited a dose-dependent manner. The amount of MDA-MB-231 cells attached to the bottom of well decreased significantly after photodynamic treatment of hypocrellin B. Flow cytometry showed that the early and late apoptotic rate of MDA-MB-231 cells increased remarkably up to 17.46% and 32.80%, respectively, after treatment of LED-activated hypocrellin B. In addition, nuclear condensation, fragmentation and chromatin margination, and topical apoptotic body in the treated cells were observed by nuclear staining and TEM.

CONCLUSION

Photodynamic action of hypocrellin B irradiated by light-emitting diodes could significantly kill breast cancer cells and induce apoptotic cell death, which suggests LED-activated hypocrellin B is a promising strategy for combating breast cancer.