Contribution of small heat shock proteins to muscle development and function

Investigations undertaken over the past years have led scientists to introduce the concept of protein quality control (PQC) systems, which are responsible for polypeptide processing. The PQC system monitors proteostasis and involves activity of different chaperones such as small heat shock proteins (sHSPs). These proteins act during normal conditions as housekeeping proteins regulating cellular processes, and during stress conditions. They also mediate the removal of toxic misfolded polypeptides and thereby prevent development of pathogenic states. It is postulated that sHSPs are involved in muscle development. They could act via modulation of myogenesis or by maintenance of the structural integrity of signaling complexes. Moreover, mutations in genes coding for sHSPs lead to pathological states affecting muscular tissue functioning.     

Various DNA content in myotube nuclei during myotomal myogenesis in Hymenochirus boettgeri (Anura: Pipidae)

During myotomal myogenesis in Hymenochirus boettgeri primary myoblasts differentiate into morphologically and functionally mature, mononucleate myotubes. Further muscle development in the studied species is due to fusion of mesenchymal cells with the latter, resulting in the presence of two classes of nuclei in the myotube: large of myotomal origin and small of mesenchymal origin. Densitometric measurements of DNA content revealed that the myotube nuclei at stages 35 reached values close to 4C DNA (3, 3C DNA), while at a later stage (42) the values were equal to 4C. Conversely, the secondary myoblast nuclei following the fusion with the myotube at stage 42 had 2C DNA--a content comparable to that found in erythrocyte nuclei. PCNA (Proliferating Cell Nuclear Antigen)--marker of S-phase of cell cycle, detected in the myotube nuclei (at stages 35, 42) appears during DNA replication.     

Esters of betulin and betulinic acid with amino acids have improved water solubility and are selectively cytotoxic toward cancer cells

Betulin and betulinic acid are naturally occurring pentacyclic triterpenes showing cytotoxicity towards a number of cancer cell lines. Unfortunately they are practically insoluble in aqueous media and therefore their overall absorption index is not satisfactory. We have modified structures of both compounds by simple transformation to mono- and disubstituted esters of l-amino acids. This allowed us to achieve better water solubility without loss of the observed earlier anticancer properties. Comet assay on various cancer cell lines demonstrate that these compounds act via an apoptotic mechanism.     

Uptake of photofrin II,a photosensitizer used in photodynamic therapy,by tumour cells in vitro

Photosensitizing dyes are used in fluorescence diagnostics and photodynamic therapy (PDT). These usually hematoporphyrin derivatives (HpD) accumulate preferentially within neoplastic tissues. HpD is a mixture of ether and ester linked porphyrins. Its partially purified form is known under the commercial name of photofrin II (PII). PII emission spectra were studied in a hydrophilic (PBS) and a lipophilic (PC liposomes) environment. Red shift was observed in their emission maxima from 615 nm in buffer solution to 635 nm in lipid. Identical red shift was obtained when the intracellular fluorescence of two cancer cell lines, MCF 7 and Jurkat, incubated with PII was investigated. Thus, intramembrane localization of PII may be suggested. As determined from the total fluorescence intensity, the uptake of PII was only slightly higher for Jurkat than for MCF 7 cells. Nevertheless the kinetics of the uptake was found to be different for both cell lines.     

Phosphonic pseudopeptides as human neutrophil elastase inhibitors--a combinatorial approach

Here we present a simple and rapid method for the construction of phosphonic peptide mimetic inhibitor libraries-products of Ugi and Passerini multicomponent condensations-leading to the selection of new biologically active phosphonic pseudopeptides. As the starting isonitriles, 1-isocyanoalkylphosphonate diaryl ester derivatives were applied. The structure of the synthesized inhibitors was designed to target human neutrophil elastase, a serine protease whose uncontrolled activity may lead to development of several pathophysiological states such as rheumatoid arthritis, cystic fibrosis or tumor growth and invasion. After screening the inhibitory activity of our constructed libraries, the most active compounds were synthesized as single molecules. One of the obtained inhibitors, Cbz-Met-O-Met-Val(P)(OC(6)H(4)-p-Cl)(2), displayed apparent second-order inhibition value at 40,105M(-1)s(-1) as the diastereomers mixture. Inhibition potency and selectivity of action toward other serine proteases as well as the results of initial in vitro experiments regarding inhibitors influence on cancer cell proliferation are presented.     

The influence of photodynamic therapy on apoptosis in human melanoma cell line

Melanoma is the most severe of all skin cancers as it may grow rapidly and metastasize. The application of photodynamic therapy (PDT) opens new perspectives in treatment of this cancer. Numerous studies suggest that the exposure of tumor cells to PDT can lead to cell death via two separate processes: apoptosis or necrosis. The aim of this study was to assess in vitro photodynamic therapy which induces apoptosis in the human Beidegr?m Melanoma (BM) cell line, using neutral comet assay. The cells were incubated with Photofrin II (15 microg/ml and 30 microg/ml) 4 h before and 3 h after irradiation for 5 or 10 min with the light intensity of 10 mW/cm2, using a lamp with red filter (632.8 nm). The percentage of apoptotic cells was significantly higher after PDT comparing to control cells. We observed 25% and 70% of apoptotic cells after shorter irradiation and treatment with 15 microg/ml and 30 microg/ml of Ph II, respectively. After longer irradiation, the respective values were 71.9% and 90%. The results suggest that induction of apoptosis is an important determinant of photodynamic sensitivity in the studied cell line and that some types of DNA damage are dependent on photosensitizer concentration and time of irradiation.     

Cellular stress induced by photodynamic reaction with CoTPPS and MnTMPyPCl5 in combination with electroporation in human colon adenocarcinoma cell lines (LoVo and LoVoDX)

Two porphyrins, CoTPPS and MnTMPyPCl₅, were tested for their photodynamic activity and potential novel use in a therapy of human cancers. We investigated an effect of photodynamic reaction (PDR), electroporation (EP) and their combination (electro-photodynamic reaction [EP-PDR]) on human colon adenocarcinoma cell lines (LoVo and resistant to doxorubicin LoVoDX), human breast adenocarcinoma (wild type MCF-7/WT and resistant to doxorubicin MCF-7/DOX), and human melanoma (Me45). The efficiency of macromolecules transport was examined with cytofluorymetry by assessing the degree of propidium iodide (PI) penetration. Additionally, cellular ultrastructure after EP was evaluated. We determined cyto- and photo-cytotoxic effect on the cells viability (MTT assay) after standard PDR and PDR combined with EP. Intracellular distribution and mitochondrial colocalization of both porphyrins was also performed. The experiments proved that both complexes exhibit desirable photodynamic properties on LoVo LoVoDX cells, and EP effectively supports photodynamic method in this type of cancer. The application of EP provided shorter time of incubation (only 10 min) and enhanced effect of applied therapy. The porphyrins did not affect the MCF-7 and Me45 cell lines.     

Cyanines as efficient photosensitizers in photodynamic reaction: Photophysical properties and <Emphasis Type="Italic">in vitro</Emphasis> photodynamic activity

The purpose of the present study was to explore the potential application of cyanines in photodynamic treatment. The photophysical features of four cyanines (KF570, HM118, FBF-749, and ER-139) were investigated by elemental and spectral analyses. Two malignant cell lines (MCF-7/WT and MCF-7/DOX) were used to test the potential for use in the photodynamic therapy. The cytotoxic effects of these dyes were determined by the MTT assay after 4 and 24 h of incubation with the cyanine. KF570 and HM118 were irradiated with red light (630-nm filter) and FBF-749 and ER-139 with green light (435-nm filter). The results showed that the cyanine HM118 demonstrated a major phototoxic effect. It was also noted that the efficiency of photodynamic therapy was higher in the doxorubicin-resistant cell line (MCF-7/DOX).