Cytotoxicity and adjuvant activity of cationic photosensitizers in a multidrug resistant cell line

Cancer and Alzheimer's disease: intracellular pH scales the metabolic disorders

Alzheimer's disease (AD) and cancer have much in common than previously recognized. These pathologies share common risk factors (inflammation and aging), with similar epidemiological and biochemical features such as impaired mitochondria. Metabolic reprogramming occurs during aging and inflammation. We assume that inflammation is directly responsible of the Warburg effect in cancer cells, with a decreased oxidative phosphorylation and a compensatory highthroughput glycolysis (HTG). Similarly, the Warburg effect in cancer is thought to support an alkaline intracellular pH (pHi), a key component of unrelenting cell growth. In the brain, inflammation results in increased secretion of lactate by astrocytes. The increased uptake of lactic acid by neurons results in the inverse Warburg effect, such as seen in AD. The neuronal activity is dampened by a fall of pHi. Pronounced cytosol acidification results in decreased mitochondrial energy yield as well as apoptotic cell death. The link between AD and cancer is reinforced by the fact that treatment aiming at restoring the mitochondrial activity have been experimentally shown to be effective in both diseases. Low carb diet, lipoic acid, and/or methylene blue could then appear promising in both sets of these clinically diverse diseases.

Gold-catalyzed tandem reaction of 2-alkynylanilines followed by 1,6-conjugate addition to p-quinone methides: efficient access to unsymmetrical diarylindolylmethanes

A simple, mild, efficient and chemoselective catalytic method for the straightforward synthesis of an interesting class of 2-aryl/alkyl-substituted-3-diaryl indolyl methanes in high yield is reported.

[The sonodynamic effects of Chlorin e6 on the proliferation of human lung adenocarcinoma cell SPCA-1]

BACKGROUND AND OBJECTIVE

Sonodynamic therapy (SDT) is a promising new approach for cancer therapy. The purpose of this study is to detect the effects of SDT on the cell proliferation of human lung adenocarcinoma cell SPCA-1, using Chlorin e6 as a sonosensitizing agent activated by ultrasound.

METHODS

SPCA-1 and normal peripheral mononuclear cell (PMNC) were treated with ultrasound or Chlorin e6 alone and combined. Cell proliferation was determined by MTT assay, and cell morphology was studied by inverted microscope after 6 h treated.

RESULTS

1.0 MHz ultrasound (1.0 W/ cm(2)-2.0 W/cm2 x 60 s) and Chlorin e6 (0.4 mg/mL-3.2 mg/mL) inhibited the cell proliferation of both SPCA-1 and PMNC cells in a intensity- and a dose-dependent manner respectively. Compared with the ultrasound (1.0 W/cm2 x 60 s) or Chlorin e6 (0.05 mg/mL-0.2 mg/mL) alone, the inhibitory effect on the cell proliferation was remarkably increased by the combination of ultrasound and chlorin e6 in SPCA-1 cells (P < 0.05), but no same effect was observed in PMNC cells (P > 0.05). Compared with the ultrasound (1.0 W/cm2 x 60 s) or chlorin e6 (0.2 mg/mL) alone, the combination treatment of ultrasound with Chlorin e6 induced more necrotic cells in SPCA-1 cells (P < 0.05).

CONCLUSION

There was a significant selectively inhibitory effect of sonodynamic effect with Chlorin e6 on the SPCA-1 cell growth. Chlorin e6 may be a promising sonosensitizing agent for the treatment of non-small cell lung cancer.

The development of phenothiazinium photosensitisers

Methylene blue has been widely used since the late 19th century in biomedical research, and was the lead compound in several important clinical areas, including therapeutics for malaria and schizophrenia. The photodynamic therapy (PDT) of cancer and, more recently, of microbial infection (photodynamic antimicrobial chemotherapy (PACT)) has also employed methylene blue and its congeners, among other chemical types, due to the low human toxicities and efficient photosensitising properties of the group. However, little work has been carried out in terms of derivative and structure-activity development, most reports covering standard, commercially available compounds. This review deals with the evolution of phenothiazinium photosensitisers for both PACT and PDT use.

Methylene blue is more toxic to erythroleukemic cells than to normal peripheral blood mononuclear cells: a possible use in chemotherapy

Methylene blue (MB) is a phenothiazine with radio and photosensitizing properties and anti-tumoral activity. Our group has shown that MB was capable of inhibiting the in vitro growth of erythroleukemic cells with multidrug resistance (MDR). However, there are no studies comparing the cytotoxicity of this molecule for normal and tumoral cells. In this work, the cytotoxicity of MB was measured by MTT method in erythroleukemic and melanoma lineages, comparing it with that of normal cells:lymphocytes and melanocytes. MB was more cytotoxic for tumoral cells; however, there was no difference between erytroleukemic cells with or without MDR phenotype. Lymphocytes and erythroleukemic cells were much more sensitive to the effects of MB than melanoma cells and melanocytes. The proliferation of phytohemagglutinin-activated lymphocytes was inhibited when 3H-thymidine incorporation to DNA was measured. We tried to analyze whether the cells were dying, via apoptosis or necrosis, using Anexin-V and propidium iodide. Despite higher levels of Anexin-V, it was not possible to distinguish necrosis from apoptosis, as the fluorescence of MB is in the same channel as propidium iodide. The production of hydrogen peroxide was measured by cytometry using dihydrorhodamine 123 (DHR). Despite the erythroleukemic cells and lymphocytes being capable of producing free radicals, there was no relation between the production and the sensitivity of various cells to MB. Our results suggest that MB should be used as a chemotherapeutic agent, because of its preferential cytotoxic effects over tumor cells, considering the fact that MDR cells are also sensitive, and due to its radio and photosensitizing activities.

The phenothiazinium chromophore and the evolution of antimalarial drugs

The phenothiazinium salt methylene blue [3,7-bis(dimethylamino)phenothiazinium chloride] is the oldest known synthetic antimalarial drug, its clinical efficacy having been reported in 1891. The role of methylene blue in the evolution of the modern antimalarial armoury is often unappreciated, yet it can be linked directly to standard drugs such as chloroquine and its congeners. Also, in the face of increasing plasmodial resistance to modern antimalarials, phenothiazinium derivatives have again featured as lead compounds in drug research. The precise mode of action of methylene blue and its commercial analogues against Plasmodium spp. remains a cause for conjecture, having been variously described as nucleic acid intercalation, food vacuole basification, parasite redox cycle interference and haem polymerization inhibition. That the activity of the series may be due to more than one route - i.e. a multifactorial activity - underlines the utility of these compounds in antimalarial research either as single drugs or as adjuvants (partners in a drug combination), particularly in the face of resistant parasitic strains.

Quinoline and cyanine dyes—putative anti-MRSA drugs

One way in which drug-resistant bacteria may be attacked is to screen new series of candidate compounds. Quaternary quinoline compounds and dyes were studied by Carl Browning (1887-1972) and Julius Cohen (1859-1935). A remarkable part of Browning and Cohen's work was the early development of structure-activity relationships for their series of compounds. Thus cationic species were found generally to be more effective antibacterials than neutrals or anionics, and the testing of partial or deconstructed active molecules was also carried out. Much of this work underpinned the fuller understanding of e.g. aminoacridine action developed by Adrien Albert (1907-1989), himself also a collaborator of Browning. Analysis of the activity of a range of compounds developed by Browning and Cohen suggests that these might again be examined as topical antimicrobials in the fight against methicillin-resistant S. aureus (MRSA) and other resistant bacteria.

A light in multidrug resistance: photodynamic treatment of multidrug-resistant tumors

The major drawback of cancer chemotherapy is the development of multidrug-resistant (MDR) tumor cells, which are cross-resistant to a broad range of structurally and functionally unrelated agents, making it difficult to treat these tumors. In the last decade, a number of authors have studied the effects of photodynamic therapy (PDT), a combination of visible light with photosensitizing agents, on MDR cells. The results, although still inconclusive, have raised the possibility of treating MDR tumors by PDT. This review examines the growing literature concerning the responses of MDR cells to PDT, while stressing the need for the development of new photosensitizers that possess the necessary characteristics for the photodynamic treatment of this class of tumor.

Intracellular localisation studies of doxorubicin and Victoria Blue BO in EMT6-S and EMT6-R cells using confocal microscopy

The subcellular localisation of doxorubicin and Victoria Blue BO (VBBO) in a murine mammary tumour cell line EMT6-S, and the resistant sub-lineEMT6-R was studied, using confocal microscopy, in order to investigate their sites of action. In cells treated with doxorubicin (10 mu M) for 90 min, the pattern of intracellular drug distribution differed between the two cell lines. Doxorubicin was found to localise mainly in the nucleus of the sensitive cell line, whereas weak fluorescence was observed in the cytoplasm of the resistant cells, in a punctuate pattern, with no nuclear involvement. The drug also appeared to be effluxed more rapidly by the resistant cell line. The accumulation of doxorubicin at various time intervals over 1h in EMT6-S cells showed that the drug clearly interacted with both the plasma membrane and the nucleus. In contrast to doxorubicin, the intracellular distribution of VBBO in both EMT6-S and EMT6-R was similar, VBBO was clearly localised throughout the cytoplasm, in a punctuate pattern, which may be consistent with the widespread distribution of mitochondria. A more apical pattern of accumulation was noted in the EMT6-R cell line. No interaction with the plasma membrane was evident. These results indicate that the main modes of action for the two drugs differ markedly, suggesting involvement of both the membrane and the nucleus in the case of doxorubicin, but mitochondrial involvement for VBBO.