Цель работи - изучить влияние фотодинамической терапии (ФДТ) на опухолевый ангиогенез и метастазирование карциномы легкого Льюис. Для ФДТ использовали фотосенсибилизатор второго поколения - 5-аминолевулиновую кислоту (5-АЛК) и лазерное излучение с длиной волны 633 нм; определяли содержание VEGF в сыворотке крови; оценивали воздействие ФДТ на рост первичной опухоли, метастазирование и неоваскуляризацию карциномы легкого Льюис у мышей. Результаты: ФДТ с использованием 5-АЛК (ФДТ-АЛК) вызывает значительное замедление роста первичной опухоли и угнетение метастатического процесса с параллельным существенным снижением уровня медиатора ангиогенеза VEGF и торможением процесса васкуляризации в легочных метастазах. Патоморфологически после проведения ФДТ-АЛК отмечается дистрофия опухолевых клеток, некробиоз и нарушение кровообращения в сосудах исследуемых опухолей. Вывод: противоопухолевый эффект ФДТ с применением 5-АЛК в качестве фотосенсибилизатора обусловлен нарушением васкуляризации и ангиогенеза в опухолевой ткани.

Індекс рубрикатора НБУВ: Р569.411 + Р411.022

Рубрики:

Пухлини кісткового мозку і крові

Лейкози(лейкемії)

Шифр НБУВ: Ж14160 Пошук видання у каталогах НБУВ 

Aim - to synthesize and to study for photodynamic activity a composite photosensitizer consisting of chlorin e6 and human serum albumin nanoparticles (HSA NPs). Starting from sorption-purified HSA, the albumin nanoparticles with a different degree of lysine residues cross-linking (10; 20; 40, and 100 %) were obtained by the coacervation method. The HSA NPs were used for synthesis of nanocomposites with chlorin e6 and fluorescein isothiocyanate (FITC)-labled preparations. Malignant lymphocytes of the MT-4 (human T-cell leukemia) line and normal lymphocytes of healthy donors served as cell targets. For photodynamic treatment, a semiconductor laser was exploited as a light source, and cell viability was assessed by MTT or trypan blue dye exclusion tests. For cell imaging and HSA NPs visualization, the fluorescence microscopy and transmission electron microscopy were applied, respectively. C57BI/6 mice were used in animal experiments. The absorption and fluorescence spectra of chlorin e6-HSA NPs composites were characterized, and by the electron microscopy investigation the size of NPs (nanospheres) was estimated: 100 - 120 nm. FITC-labled albumin preparations allowed to establish that HSA NPs have much higher exposition and concentration dependent affinity to malignant cell surface than initial HSA. In experiments with MT-4 cells on PDT activity of chlorin e6-HSA NPs, the nanocomposite effectiveness elevated along with increasing percentage of cross-linked aminoacid residues, and for the nanocomposite with 100 % of albumin cross-linking it exceeded the activity of free chlorin e6. In contrast to malignant cells, the complexation of chlorin e6 with HSA NPs decreased its photodynamic effect on normal human lymphocytes. Intravenous introduction of the chlorin e6-HSA NPs composite to mice showed prolonged circulation of the nanocomposite in blood in comparison with free PS. Conclusion: promising results obtained with chlorin e6-HSA NPs composites warrant conduction of full-fledged PDT studies in vivo using the nanocomposites as photosensitizers.

Background: photodynamic therapy (PDT) is considered as a possible alternative approach to overcoming multidrug resistance (MDR). Analysis of cross-resistance to PDT in cells with different MDR pathways and resistance levels seems to be advantageous for elucidating the general mechanisms of cancer cell resistance to various treatment modalities. Aim - the aim of the study was to clarify whether the Jurkat/A4 leukemia cells with MDR phenotype are cross-resistant to PDT. Human T-cell acute lymphoblastic leukemia line Jurkat and Jurkat/A4 subline with MDR phenotype were used. 5-Aminolevulinic acid (ALA) and Photolon (a complex of chlorine-e6 and polyvinylpyrrolidone; PL) or gold nanocomposite of PL were applied as photosensitizers. The cells were pretreated with photosensitizers and exposed to laser radiation at corresponding wavelengths. The phototoxicity was assessed in trypan blue exclusion test. The hypodiploid cell fraction was analyzed by flow cytometry of propidium iodidestained cells. Expression of genes related to PDT resistance was analyzed by micro array technique with Affymetrix U133A chips. ALA-mediated PDT resulted in dose-dependent cell death in both lines, the relative photodynamic efficacy in Jurkat/A4 cells being inferior to that in the parental Jurkat cells. There was no correlation between phototoxicity and apoptosis induction both in Jurkat and Jurkat/A4 cells. PL-mediated general phototoxicity in Jurkat cells amounted up to 75 % at the maximal photosen-sitizer dose with about 40 % of apoptotic death fraction. PL-phototoxicity in Jurkat/A4 cells was considerably lower. In contrast to Jurkat cells, PL-gold composite did not increase the efficacy of photosensitization as compared to free PL in Jurkat/A4 cells. Conclusions: multidrug-resistant Jurkat/A4 cells exhibit reduced sensitivity to phototoxic effect in comparison with parental Jurkat cells independently of nature of the photosensitizer being assayed.

In research of the last decade, rhythmic (circadian) variations of vascular endothelial growth factor (VEGF) production by tumors were discovered. The present paper authors have earlier synthesized and characterized a new derivative photosensitizer - an immunoconjugate of hematoporphyrin with antiVEGF antibodies. Aim - to elaborate and to test a novel modification of the photodynamic therapy of tumors (PDT) method, founding upon a timed introduction of the immunoconjugated photosensitizer to tumor-bearing animals, so that this coincides with a maximum content of VEGF in tumor tissues. Circadian variations of VEGF contents in murine transplanted tumors, Lewis lung carcinoma and sarcoma 180, were determined by ELISA method. Immunoconjugated photosensitizer concentrations in tumors were estimated by spectrofluorometry. Photoirradiation of the tumors was carried out with a red light (wavelength of 635 nm) from a semiconductor laser. Light doses were chosen, calculating on a partial inhibition of tumor growth, in order that a dependence of PDT efficiency on a daily time-moment (circadian rhythm phase) of the treatment could be observed distinctly. Circadian variations of the VEGF levels in Lewis lung carcinoma and sarcoma 180 were demonstrated with the maximum at 14:00 h and the minimum at 02:00 h. Intra-abdominal introduction into tumor-bearing mice of the immunoconjugated photosensitizer resulted in a greater accumulation of the immunoconjugate in tumors at 14:00 h than at 02:00 h. Laser irradiation of carcinomas and sarcomas at 14:00 h or 02:00 h after introduction of the immunoconjugated photosensitizer to mice the day before at the same time points, induced a significantly enhanced inhibition of tumor growth in animals treated at day-time versus those treated at night-time. Conclusion: the obtained results justify further attempts to transfer principles of tumor chronochemotherapy onto photodynamic therapy.