[Importance of expression of DNA repair proteins in non-small-cell lung cancer]. / Význam stanovovania expresie DNA reparacných mechanizmov u nemalobunkového karcinómu plúc.

BACKGROUND: Proteins XRCC1 and ERCC1 are involved in DNA repair. XRCC1 plays a role in DNA base excision repair and ERCC1 in nucleotide excision repair pathway. Higher expression profile of both proteins in cancer cells may contribute to development of drug resistance. ERCC1 is involved in removal of platinum adducts and might be a potential predictive and prognostic marker in NSCLC (non-small-cell lung cancer) treated with a cisplatin-based regimen. The purpose of study was determination of XRCC1 and ERCC1 levels and their correlation with basic clini-copathological parameters in NSCLC. PATIENTS AND METHODS: In this study, 107 tumor samples diagnosed as NSCLC were immunohistochemically examined for expression of XRCC1 and ERCC1 proteins. Our results were compared to basic clinicopathological parameters: type of tumor, tumor grade and stage of disease. For statistical analysis, the chi-square test was used. RESULTS: In squamous cell carcinoma and large cell carcinoma samples, the XRCC1 protein level was twofold higher (60% of positive samples) than in adenocarcinoma samples (35.5% of positive samples). We have found statistical correlation between XRCC1 protein expression and type of tumor (p = 0.0306). On the other hand, the statistical importance between the protein level versus grade and stage was not found. In the case of the ERCC1 protein, we observed the highest protein level in adenocarcinoma (64.5%) and squamous cell carcinoma (62.5%) samples. Next, we determined a significant difference in content of XRCC1 versus ERCC1 (35.5% vs 64.5%) in adenocarcinoma samples. Statistical chi-square test did not reveal any correlation between ERCC1 status and clinicopathological parameters. CONCLUSION: According to our results, XRCC1 represents an important mechanism of DNA repair in squamous cell and large cell carcinomas. Besides that, expression of XRCC1 was in correlation with type of tumor. In patients with adenocarcinoma and squamous cell carcinoma, we could assume increased resistance to platinum-based therapy because of high expectation of ERCC1 protein expression. However, its levels did not correlate with monitored clinicopathological parameters. The ERCC1 protein will be possibly an independent prognostic factor in NSCLC. To prove a true survival benefit of patients with expression of ERCC1, prospective validation of ERCC1 before clinical implication is needed in the future.

Cytogenetic abnormalities predict treatment-free interval and response to therapy in previously untreated chronic lymphocytic leukemia patients.

We evaluated the prognostic impact of chromosomal abnormalities as detected by interphase fluorescence in situ hybridization (iFISH) in 86 chronic lymphocytic leukemia (CLL) patients. Overall, 39 of 86 (45%) patients displayed one (35%) or more (10%) chromosomal abnormalities, del13q (31%) being more frequently detected than trisomy 12 (19%) followed by del11q (17%), del17p (6%) and del6q (5%). Significant differences in the treatment free intervals (TFIs) were observed among individual cytogenetic subgroups (p=0.027) with the shortest mean TFIs in subgroups with del17p, del11q and trisomy 12 (10, 12 and 14 months, respectively) as compared to subgroups with normal cytogenetics (38 months) and del13q (68 months). Poor response to therapy was observed in subgroups with del11q (p=0.044) and trisomy 12 (p=0.047) while patients with normal cytogenetics had good response (p=0.003). Furthermore, del17p and del11q were associated with highest tumor burden and disease activity as reflected by corresponding laboratory data.

MDR1 (C3435T) polymorphism: relation to the risk of breast cancer and therapeutic outcome.

P-glycoprotein (PGP), the product of the MDR1 gene, is a transmembrane active efflux pump for a variety of carcinogens and cytostatics. It has been suggested that MDR1 polymorphisms contribute to the variability in cancer risk and therapeutic outcome. We examined the relevance of C3435T polymorphism in relation to breast cancer susceptibility, clinical and pathological characteristics of breast carcinoma, the therapeutic response and hematologic toxicities after anthracycline-based chemotherapy. A significant association between allele frequencies and histological type, stage and histological grade was observed (P=0.024, 0.014, 0.006, respectively, chi(2)-test or Fisher's exact test). We also found significantly higher (P=0.019, chi(2)-test) T allele frequency in breast cancer patients (n=221) than in controls (n=113). A significantly enhanced therapeutic outcome after neoadjuvant therapy (n=38; P=0.021, Fisher's exact test) and longer time to progression after anthracycline-based chemotherapy (n=102; P=0.049, log-rank test) were observed in CC homozygotes. However, no significant association between hematologic toxicities and C3435T polymorphism was detectable.

Antiangogenic effect of selected phytochemicals.

Angiogenesis, the formation of new blood vessels from a preexisting vascular network is considered a key step in tumour growth, invasion, and metastasis. Recent studies show that several natural compounds inhibit angiogenesis and nowadays numerous bioactive plant compounds are tested for their antiangiogenic potential. This review examines current knowledge regarding the antiangiogenic potential of several phytochemicals, including polyphenols resveratrol and curcumin as well as miscellaneous compounds from garlic, Hypericum perforatum, Panax ginseng, Coptis chinensis and Rheum palmatum.

In vitro antiproliferative and antiangiogenic effects of Flavin7.

Flavin7 (F7) is a nutritional supplement often taken by cancer patients in Central Europe during chemo- and radiation therapy. In this study, investigation of the antiproliferative and antiangiogenic activities of this supplement were performed. Flavin7 showed antiproliferative activity in Jurkat as well as in HeLa cells. It significantly reduced the growth of both cancer cell lines at the doses of 200 microg/ml to 20 microg/ml (p<0.001 and p<0.01, respectively). In F7-treated Jurkat cells we found a significant increase in the fraction of cells with sub-G(0)/G(1) DNA content, which is considered to be a marker of apoptotic cell death. Apoptosis was also confirmed by annexin V staining and DNA fragmentation. Furthermore, F7 at the doses of 100 microg/ml to 4 microg/ml inhibited endothelial cell migration and capillary tube formation what indicates its potential antiangiogenic properties. Flavin7 also inhibited the activity of matrix metalloproteinases (MMPs), preferentially MMP-9, at the doses of 100 microg/ml to 4 microg/ml. Our data suggest that F7 possesses marked antiproliferative and antiangiogenic properties in vitro. Further research is needed to elucidate also its in vivo activities.

Nucleic acid amplification technique for detection of Chlamydia trachomatis infection from clinical urogenital swabs.

An improved nucleic acid amplification test (NAAT) to detect Chlamydia trachomatis infections, based on PCR amplification within its cryptic plasmid (CT1/CT2 Test) was developed. DNA was extracted from urogenital swabs and a 594-bp long DNA fragment from the cryptic plasmid (pCT) was amplified. The sensitivity and specificity of the CT1/CT2 Test were determined to be 100 and 99%, respectively, when directly compared with current amplification kit for sexually transmitted diseases (MPCR). Basic epidemiological data related to the patients attending gynecological and/or urological clinics are also provided. The overall prevalence rate in this group of patients suspected for C. trachomatis infection was determined to be about 95 per 1000 (88 and 107 per 1000 in females and males, respectively). It demonstrates that the CT1/CT2 Test is suitable for epidemiological screening and/or diagnostic practice.

Molecular detection of Ureaplasma urealyticum infection from clinical urogenital swabs.

A simple nucleic acid amplification test (NAAT) was developed for detection of Ureaplasma urealyticum infection based on the PCR amplification of the urease gene (UU1/UU2 Test). DNA was extracted from urogenital swabs and a 225-bp long DNA fragment was amplified by PCR. NAAT was compared to the commercial amplification kit for sexually transmitted disease reference assay. The sensitivity and specificity of the UU1/UU2 Test were determined to be 100 and 98.9%, respectively. The overall prevalence rate in this group of patients was found to be about 236 per 1000 (283 and 166 per 1000 in females and males, respectively). These data demonstrate that UU1/UU2 Test is suitable for effective epidemiological screening and/or diagnostic practice.

Expression of MDR proteins in breast cancer and its correlation with some clinical and pathological parameters.

The aim of this work was to determine the expression of the multidrug resistance (MDR) proteins, namely MDR1 (P-glycoprotein), MRP1 (multidrug resistance-related protein) and LRP (lung resistance-related protein), in 87 samples of breast carcinoma. Detection of these proteins was provided by using indirect enzymatic immunohistochemistry. Our findings were compared with the other clinical and pathological parameters: expression of Her2/neu, estrogen receptor status (ER), progesteron receptor status (PR), histological grade and regional lymph node status. For statistical analysis, non-parametric two sided Mann-Whitney-U test was used. Majority of breast carcinoma specimens show positivity for these proteins. The MDR1 and MRP1 signal was found in the cytoplasm of cancer cells. The expression of LRP was detected in the cytoplasm close to the nuclear membrane. The samples were positive for MDR1 protein in 57%, for MRP1 in 84% and for LRP in 79%. Comparing our results with other clinical and pathological parameters, negative correlation between ER, PR and MDR1 expressions and histological grading status was found. No associations were observed between the MRP1 and LRP proteins and histological grading, as well as between the expression of three MDR proteins and the other clinically relevant parameters. In conclusion, high frequency of expression of MDR proteins in breast carcinoma cells suggests, that these proteins might be an important factor of drug resistance in breast carcinoma. Nevertheless, the negative correlation between the histological grade of malignancy of tumor and the expression of ER, PR and MDR1 indicates possible influence of progressive tumor cell de-differentiation. However, this finding has to be confirmed in additional evaluations.

Cruciferous phytoalexins: antiproliferative effects in T-Jurkat leukemic cells.

We tested antiproliferative activity of selected cruciferous phytoalexins including brassinin, 1-methoxybrassinin, (+/-)-spirobrassin, (+/-)-1-methoxyspirobrassinin and (+/-)-1-methoxyspirobrassinol, in leukemic Jurkat cell. The most effective of the tested phytoalexins was 1-methoxybrassinin with IC(50) 10 micromol l(-1). However, significant effect of all phytoalexines was also determined at concentration 1 micromol l(-1). In 1-methoxybrassinin-treated Jurkat cells, we found significant increase in the fraction of cells with a sub-G(0)/G(1) DNA content, which is considered to be a marker of cell death by apoptosis. Apoptosis was also confirmed by the annexin V staining. In summary, 1-methoxybrassinin exerted potent antiproliferative activity probably due to cell cycle arrest and apoptosis induction.

Overexpression and amplification of the met/HGF receptor gene during the progression of colorectal cancer.

The c-met oncogene encodes the receptor for hepatocyte growth factor/scatter factor, a potent mitogen for epithelial cells that also promotes cell motility and invasiveness. We have studied the changes of c-met gene expression that occur during the progression of colorectal tumors. Sixteen adenomas, 123 primitive carcinomas, and 25 liver metastases were examined. In several instances it was possible to compare same-patient samples of normal colon mucosa against primary tumor and primary carcinoma against synchronous metastasis. The expression of the c-met gene was increased from 5- to 50-fold in about 50% of tumors, at any stage of progression, and in 70% of liver metastases. Overexpression was associated with amplification of the c-met gene in only 10% of carcinomas, but in 8 of 9 metastases examined. These data suggest that overexpression of the c-met oncogene contributes a selective growth advantage to neoplastic colorectal cells at any stage of tumor progression. Moreover, amplification appears to give a further selective advantage for the acquisition of metastatic potential.

Polyphosphoinositide metabolism in polymorphonuclear cells from healthy and thermally injured rats: effect of the immunomodulator RU 41740.

Burn trauma is associated with alterations of various components of host defenses, including impaired neutrophil functions. In an animal model of experimental thermal injury, we studied if the modifications of cellular reactivity result from alterations in signalling systems by comparing polyphosphoinositide breakdown, particularly the production of inositol phosphates (IP, IP2 IP3), in healthy and burned rat polymorphonuclear neutrophil leukocytes (PMNs). Neutrophil activators such as N-formyl-methionyl-leucyl-phenylalanine (fMLP) and serum-opsonized zymosan increased in vitro production of inositol phosphates in PMNs from healthy rats. The immunomodulator RU 41740 had no effect by itself, but decreased the stimulating effect of fMLP and zymosan. In PMNs from burned rats, the stimulating effects of fMLP and zymosan were decreased, while RU 41740 stimulated inositol phosphate generation. In vivo treatment with RU 41740 inhibited the activation of phosphoinositide metabolism by fMLP or zymosan in healthy rat PMNs. Similar treatment of burned rats after injury restored the stimulating effect of fMLP and zymosan on inositol phosphate accumulation in PMNs. Thus, RU 41740 can modulate fMLP and zymosan receptor-mediated signal transduction, inducing an attenuation of the phosphatidylinositol hydrolysis response. After burn injury, when the activating effects of fMLP and zymosan are inhibited, RU 41740 can, on the contrary, stimulate phospholipase C-mediated polyphosphoinositide turnover and the formation of intracellular messengers such as IP3. These data show that RU 41740 has different effects on polyphosphoinositide metabolism in rat PMNs, according to the physiological and pathological state of the animals. Interestingly, it has a beneficial action on the post-burn decrease in PMN reactivity.

Diazepam enhances hypericin-induced photocytotoxicity and apoptosis in human glioblastoma cells.

Glioblastoma multiforme (GBM) is neoplasm which is resistant to all currently used treatment modalities including surgery, radiation therapy and chemotherapy. Photodynamic therapy (PDT) has been suggested as a novel therapeutical approach to the treatment of malignant gliomas. Here, we attempted to enhance hypericin-induced photocytotoxicity and apoptosis by diazepam, a non-selective ligand of peripheral benzodiazepine receptors (PBR) which seem to play an important role in apoptosis regulation. For the study, we used U-87 MG and U373 MG glioma cell lines and primary cultures of GBM cells prepared from peroperatively obtained tumor specimens. The patients included 7 histologically confirmed GBMs. Colorimetric MTT assay was employed to study the photocytotoxic effects of hypericin and diazepam. Flow cytometry was used to detect apoptosis and assess the proapoptotic effects of diazepam. We found that hypericin upon photoactivation exerts strong cytotoxic effects against U-87 MG and U373 MG cells as well as primary GBM cell cultures. No cytotoxic effect of hypericin was observed under dark conditions. Diazepam inhibited cell growth in U-87 MG cells and primary cultures whereas proliferation of U373 MG cells remained unaffected. When hypericin was combined with diazepam, photocytotoxicity was increased in U-87 MG cells and primary cultures unlike U373 MG cells. Flow cytometric analysis revealed photoactivated hypericin-induced apoptosis in both cell lines. Apoptosis was significantly enhanced by diazepam in U-87 MG cells. However, no such effect was observed in U373 MG cells. In the present study, we showed that photocytotoxic effect of hypericin in glioma cells can be potentiated by diazepam. This effect is underlied by the ability of diazepam to facilitate hypericin-induced apoptosis. This work provides support to performe clinical studies involving diazepam in the antiglioma treatment regimens as an apoptosis-modulating agent.

Effect of stobadine on carbon tetrachloride-induced erythrocyte membrane changes in rats.

Our previous study showed that stobadine is effective against ischemia/reperfusion-induced gastric mucosal injury. The present study examined the ability of stobadine to protect erythrocyte membrane against free radical injury after long-term carbon tetrachloride (CCl4) application. The erythrocyte membrane changes were established using colloid-osmotic hemolysis. The significant increase of colloid-osmotic hemolysis was found in animals treated with CCl4. CCl4 also increased formation of thiobarbituric acid-reactive substances (TBARs) and decreased thiol group content. Stobadine in both doses (10.0 and 20.0 mg.kg-1) protected erythrocyte membrane against CCl4-induced injury. The membrane lipid bilayer is the most affected part of the erythrocyte membrane. In presence of stobadine, CCl4-induced lipid peroxidation was partially or totally prevented whereas the level of total membrane thiols was increased. Based on these results, it can be concluded that protective effect of stobadine on CCl4-induced erythrocyte membrane changes should be related to its antioxidant properties.

Interaction of VIP, PACAP and related peptides in normal and leukemic human monocytes and macrophages.

The activation of the cAMP signaling pathway by vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP) and related peptides was studied (i) in normal peripheral human monocytes and THP-1 leukemic human monocytes, (ii) in their derived macrophage counterparts respectively obtained after spontaneous differentiation or retinoic acid (RA) treatment, and (iii) in human bronchoalveolar macrophages. In THP-1 monocytes, PACAP increased basal adenylate cyclase activity 5.3-fold, with an affinity 50-times greater than that of VIP or helodermin (Ka = 3.2 x 10(-11) M VIP), whereas in normal peripheral monocytes, PACAP and VIP exhibited similar affinities and only increased cAMP generation 2-fold (EC50 = 10(-9) M). Spontaneous and RA-induced differentiation into normal and leukemic macrophages induced a progressive loss of cAMP production and regulation of superoxide anion production by VIP and related peptides. The neoplastic transformation in THP-1 monocytes and the deficiencies in the cAMP cascade observed during the terminal differentiation of normal and leukemic human macrophages may relate to a differential genetic expression of the VIP/PACAP receptor subtypes, and alterations in the functional activity of the stimulatory and inhibitory Gs/Gi subunits of adenylate cyclase.

Cyclic amp-responsive gene-transcription in cellular proliferation and transformation.

The proteins binding the cAMP responsive elements constitute a family of transcription factors (e.g. CREB 327/341, ATF, HB16, CREM) which operate as dimers and regulate positively and negatively gene expression upon interaction with the cAMP responsive motifs CRE/ATF. These proteins regulate transcription after cAMP- dependent phosphorylation (CREB), or interaction with the adenovirus E1A oncoprotein (ATF-2). Subtle modulation might be further attained by the cross-talk between the different signal-transduction pathways and the heterodimerization of different classes of transcription factors. The CREB/ATF transcription factors therefore exert a pleiotropic action during the integration of extra/intra cellular signals in the resulting adaptation of cellular responses. Dysregulation might be associated with pathological situations related to the uncontrolled cell proliferation, oncogenic progression and metastasis.

Functional expression of VIP receptors in normal, immortalized and transformed mammary epithelial cells.

The effect of VIP and its related peptides on cAMP production has been characterized: 1) in long term culture of normal human mammary epithelial cells (HMEC); 2) in immortalized and transformed ST cell lines established from normal HMEC after genomic insertion of the large T oncogene of SV40; 3) in the spontaneously immortalized HC-11 cells, a clone isolated from the mouse mammary epithelial cells COMMA-1D, described to exhibit normal morphogenesis in vivo and functional differentiation in vitro. Basal cAMP levels were increased 1.5- to 8.7-fold in mammary epithelial cells (p less than 0.001-0.05), with a potency EC50 = 0.02-0.6 nM VIP. The pharmacological specificity of the VIP receptors coupled to cAMP generation was established according to the following potency sequence: VIP greater than PACAP-38 greater than helodermin greater than PHM, PHV greater than helospectin 1 much greater than hpGRF, secretin in HMEC, VIP greater than PACAP-38 greater than helodermin greater than helospectin 1, PHM, PHV greater than hpGRF greater than secretin in S1T3 cells, and VIP, PHI, helodermin greater than PHV greater than rhGRF greater than secretin in HC-11 cells. Our data demonstrate the presence of functional, highly sensitive and specific VIP receptors in normal, immortalized and transformed mammary epithelial cells, suggesting a regulatory role for this neuropeptide on the growth, differentiation and function in normal and neoplastic breast tissue.

Diazepam enhances etoposide-induced cytotoxicity in U-87 MG human glioma cell line.

Various approaches might be employed in an effort to increase efficacy of the chemotherapeutic treatment of cancer. Recently, various modulators of anticancer therapy effectiveness have been studied. Antiproliferative effects of peripheral benzodiazepine receptor (PBR) ligands might be exploited to enhance cytotoxic effect of a chemotherapeutic drug towards cancer cells. In this work, we sought to enhance cytotoxic effect of etoposide (VP-16) by a PBR ligand, diazepam (DZ) in U-87 MG human glioma cells. Cytotoxicity of VP-16, DZ and their combinations was assessed by using the microculture MTT assay. Cell survival, effective concentrations (EC) and the onset of cytotoxic effect were determined. After 72 h of cultivation, survival of U-87 MG cells was reduced to 57 +/- 7% in the presence of VP-16 at 12.5 microg/mL alone, whereas DZ at 10-4 mol/L alone caused 28 +/- 6% reduction in cell survival. Coincubation of VP-16 at 12.5 microg/mL with DZ at 10-4 mol/L led to a further decrease in cell survival to 45 +/- 6%. Furthermore, DZ at 10-4 mol/L significantly decreased effective concentrations, EC10, EC30 and EC50, of VP-16 and the dose-response curves were shifted to the left. Addition of DZ at 10-4 mol/L to VP-16 also facilitated the onset of its cytotoxic effect. The same decrease in survival was thus achieved approximately 30 h earlier in comparison with VP-16 alone. However, DZ at 10-9 mol/L failed both to exert any effect on glioma cells survival and enhance cytotoxic effect of VP-16. DZ at 10-4 mol/L was capable of both reducing U-87 MG glioma cells survival when applied alone and also enhancing the cytotoxic effect of VP-16. No such observation was made for the lower concentrations of DZ. Potential implementation of diazepam in the antiglioma/anticancer armamentarium awaits further experimentation but phase I and phase II clinical trials could be suggested.

Effects of static magnetic field on human leukemic cell line HL-60.

A number of structures with magnetic moments exists in living organisms that may be oriented by magnetic field. While most experimental efforts belong to the area of effects induced by weak and extremely low-frequency electromagnetic fields, we attempt to give an attention to the biological effects of strong static magnetic fields. The influence of static magnetic field (SMF) on metabolic activity of cells was examined. The metabolic activity retardation is observed in human leukemic cell line HL-60 exposed to 1-T SMF for 72 h. The retardation effect was observed as well as in the presence of the mixture of the antineoplastic drugs 5 fluorouracil, cisplatin, doxorubicin and vincristine.

Expression of the multidrug resistance-associated protein 1 (MRP1) and the lung resistance-related protein (LRP) in human lung cancer.

Fifty lung cancer samples (41 non-small cell lung cancer-NSCLC and 9 small cell lung cancer-SCLC) were immunohistochemically analyzed for lung resistance-related protein (LRP) and multidrug resistance-associated protein 1 (MRP1) expressions which were then correlated with histopathological subtype of the tumor. To detect these proteins, monoclonal antibodies LRP-56 and MRPm6 were used. NSCLC samples were divided into two groups, adenocarcinomas (17 samples) and squamous cell carcinomas (24 samples). Four categories of LRP and MRP1 quantity were distinguished: +++ = high level--90--100% of positive cells, ++ = lower level--10--90% of positive cells, + = low level--up to 10% of positive cells, - = negative cells--0% of positive cells. Within the NSCLC group the most samples (36/41) had the similar level of LRP and MRP1. Significantly higher expression of both proteins was observed in the adenocarcinomas in comparison with squamous cell carcinomas. The lowest positive staining for LRP and MRP1 proteins has been found in SCLC. It is suggested that our finding can confirm the overall empirical clinical knowledge about much higher chemosensitivity of untreated SCLC comparing to NSCLC.

Effect of stobadine on indomethacin- and ethanol-induced stomach lesions and gastric secretion.

Stobadine was found to inhibit the ulcerogenic activity of indomethacin in relation to the dose but was ineffective against the direct necrotizing action of ethanol. It also inhibited gastric acid secretion when administered intraduodenally. Although stobadine is considered to be a scavenger of free radicals, our results indicate that, under the given experimental conditions, it is rather the inhibition of gastric acid secretion that is responsible for its antiulcerogenic effect. The preliminary results do not allow the exclusion of other mechanisms for explaining its antiulcerogenic effect.