RENEB Inter-Laboratory Comparison 2021: The Cytokinesis-Block Micronucleus Assay

The goal of the RENEB inter-laboratory comparison 2021 exercise was to simulate a large-scale radiation accident involving a network of biodosimetry labs. Labs were required to perform their analyses using different biodosimetric assays in triage mode scoring and to rapidly report estimated radiation doses to the organizing institution. This article reports the results obtained with the cytokinesis-block micronucleus assay. Three test samples were exposed to blinded doses of 0, 1.2 and 3.5 Gy X-ray doses (240 kVp, 13 mA, ∼75 keV, 1 Gy/min). These doses belong to 3 triage categories of clinical relevance: a low dose category, for no exposure or exposures inferior to 1 Gy, requiring no direct treatment of subjects; a medium dose category, with doses ranging from 1 to 2 Gy, and a high dose category, after exposure to doses higher than 2 Gy, with the two latter requiring increasing medical attention. After irradiation the test samples (no. 1, no. 2 and no. 3) were sent by the organizing laboratory to 14 centers participating in the micronucleus assay exercise. Laboratories were asked to setup micronucleus cultures and to perform the micronucleus assay in triage mode, scoring 500 binucleated cells manually, or 1,000 binucleated cells in automated/semi-automated mode. One laboratory received no blood samples, but scored pictures from another lab. Based on their calibration curves, laboratories had to provide estimates of the administered doses. The accuracy of the reported dose estimates was further analyzed by the micronucleus assay lead. The micronucleus assay allowed classification of samples in the corresponding clinical triage categories (low, medium, high dose category) in 88% of cases (manual scoring, 88%; semi-automated scoring, 100%; automated scoring, 73%). Agreement between scoring laboratories, assessed by calculating the Fleiss' kappa, was excellent (100%) for semi-automated scoring, good (83%) for manual scoring and poor (53%) for fully automated scoring. Correct classification into triage scoring dose intervals (reference dose ±0.5 Gy for doses ≤2.5 Gy, or reference dose ±1 Gy for doses >2.5 Gy), recommended for triage biodosimetry, was obtained in 79% of cases (manual scoring, 73%; semi-automated scoring, 100%; automated scoring, 67%). The percentage of dose estimates whose 95% confidence intervals included the reference dose was 58% (manual scoring, 48%; semi-automated scoring, 72%; automated scoring, 60%). For the irradiated samples no. 2 and no. 3, a systematic shift towards higher dose estimations was observed. This was also noticed with the other cytogenetic assays in this intercomparison exercise. Accuracy of the rapid triage modality could be maintained when the number of manually scored cells was scaled down to 200 binucleated cells. In conclusion, the micronucleus assay, preferably performed in a semi-automated or manual scoring mode, is a reliable technique to perform rapid biodosimetry analysis in large-scale radiation emergencies.

C88 EFFECT OF SARS–COV2 INFECTION ON ACUTE CORONARY SYNDROME: A RETROSPECTIVE OBSERVATIONAL STUDY

Introduction

In Northern Italy, from October 2020 to April 2021, the second wave of COVID–19 pandemic recorded the highest incidence of infections ever. In this semester, the Lombardy region alone counted 43,318 positive cases and 16,710 deaths. It is well known how COVID–19 leads to a negative prognosis in acute coronary syndrome (ACS). This study aims to analyze the dramatic consequences of SARS–CoV2 infection on patients with concomitant ACS during the worst pandemic period ever recorded in Northern Italy.

Materials and Methods

The study enrolled 255 consecutive patients who have been hospitalized for ACS (STEMI or NSTEMI) from October 2020 to April 2021, both from the hub and spoke hospitals. Two subgroups are compared: the first is composed of patients who have tested positive for at least one molecular SARS–CoV2 swab (at admission or during hospitalization), the other group is composed of patients who have been tested negative to SARS–CoV2 swab. Major clinical data, risk factors (RF), comorbidities, laboratory findings, reperfusion times, drug therapy, complications and in–hospital mortality were systematically collected.

Results

Patients main characteristics are shown in Table 1. No differences have been observed in clinical history, RF and comorbidities in the subgroups. At admission, the incidence of acute pulmonary edema (APE) and respiratory symptoms was significantly higher in the SARS–CoV2 group, respectively 14% (p = 0.005) and 18% (p = 0.017). No differences in the “onset to door” and “door to needle” delays have been recorded. The incidence of the composite in–hospital complications is markedly increased in SARS–CoV2 group. Compared to negative patients, a higher mortality rates (18% Vs. 4%; p = 0.017), higher incidences of acute renal failure (ARF) (18% Vs. 5%; p = 0.037), cardiogenic shock (14% Vs. 3%; p = 0.033) and a wider prescription of inotropes (23% Vs. 10%; p = 0.009) in the SARS–CoV2 cohort.

Conclusion

The study confirms the negative prognostic impact of COVID–19 infection on ACS, recording a significantly higher rate of all major complications, both related to ischemia with multiorgan failure and interstitial pneumonia. Higher incidence of APE, cardiogenic shock and ARF has been observed in SARS–CoV2 positive subgroup, which is corroborated by a quadrupled risk of in–hospital mortality in the COVID–19 cohort.

Inflammatory cues acting on the adult intestinal stem cells and the early onset of cancer (review)

The observation that cancer often arises at sites of chronic inflammation has prompted the idea that carcinogenesis and inflammation are deeply interwoven. In fact, the current literature highlights a role for chronic inflammation in virtually all the steps of carcinogenesis, including tumor initiation, promotion and progression. The aim of the present article is to review the current literature on the involvement of chronic inflammation in the initiation step and in the very early phases of tumorigenesis, in a type of cancer where adult stem cells are assumed to be the cells of origin of neoplasia. Since the gastrointestinal tract is regarded as the best-established model system to address the liaison between chronic inflammation and neoplasia, the focus of this article will be on intestinal cancer. In fact, the anatomy of the intestinal epithelial lining is uniquely suited to study adult stem cells in their niche, and the bowel crypt is an ideal developmental biology system, as proliferation, differentiation and cell migration are all distributed linearly along the long axis of the crypt. Moreover, crypt stem cells are regarded today as the most likely targets of neoplastic transformation in bowel cancer. More specifically, the present review addresses the molecular mechanisms whereby a state of chronic inflammation could trigger the neoplastic process in the intestine, focusing on the generation of inflammatory cues evoking enhanced proliferation in cells not initiated but at risk of neoplastic transformation because of their stemness. Novel experimental approaches, based on triggering an inflammatory stimulus in the neighbourhood of adult intestinal stem cells, are warranted to address some as yet unanswered questions. A possible approach, the targeted transgenesis of Paneth cells, may be aimed at 'hijacking' the crypt stem cell niche from a status characterized by the maintenance of homeostasis to local chronic inflammation, with the prospect of initiating neoplastic transformation in that site.

Influence of infection on the distribution patterns of NIH-Chronic Prostatitis Symptom Index scores in patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a complex condition for which the etiological determinants are still poorly defined. To better characterize the diagnostic and therapeutic profile of patients, an algorithm known as UPOINT was created, addressing six major phenotypic domains of CP/CPPS, specifically the urinary (U), psycho-social (P), organ-specific (O), infection (I), neurological/systemic (N) and muscular tenderness (T) domains. An additional sexual dysfunction domain may be included in the UPOINT(S) system. The impact of the infection domain on the severity of CP/CPPS symptoms is a controversial issue, due to the contradictory results of different trials. The aim of the present retrospective study was to further analyze the extent to which a positive infection domain of UPOINTS may modify the pattern of CP/CPPS symptom scores, assessed with the National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI). In a cohort of 935 patients that was divided on the basis of the presence or absence of prostatic infection, more severe clinical symptoms were shown by the patients with infection (median NIH total score: 24 versus 20 points in uninfected patients; P<0.001). Moreover, NIH-CPSI score distribution curves were shifted towards more severe symptoms in patients with a positive infection domain. Division of the patients into the six most prominent phenotypic clusters of UPOINTS revealed that the ‘prostate infection-related sexual dysfunction’ cluster, including the highest proportion of patients with evidence of infection (80%), scored the highest number of NIH-CPSI points among all the clusters. To assess the influence of the infection domain on the severity of patients’ symptoms, all subjects with evidence of infection were withdrawn from the ‘prostate infection-related sexual dysfunction’ cluster. This modified cluster showed symptom scores significantly less severe than the original cluster, and the CPSI values became comparable to the scores of the five other clusters, which were virtually devoid of patients with evidence of infection. These results suggest that the presence of pathogens in the prostate gland may significantly affect the clinical presentation of patients affected by CP/CPPS, and that the infection domain may be a determinant of the severity of CP/CPPS symptoms in clusters of patients phenotyped with the UPOINTS system. This evidence may convey considerable therapeutic implications.

Topographic and quantitative relationship between prostate inflammation, proliferative inflammatory atrophy and low-grade prostate intraepithelial neoplasia: a biopsy study in chronic prostatitis patients

Inflammatory processes are important components in the pathogenesis of many human cancers. According to the 'injury and regeneration' model for prostate carcinogenesis, injury caused by pathogens or pro-inflammatory cytotoxic agents would trigger proliferation of prostatic glandular cells, leading to the appearance of epithelial lesions named 'Proliferative Inflammatory Atrophy' (PIA). Inflammatory cells infiltrating the prostate would release genotoxic reactive oxygen species, leading atrophic cells to neoplastic progression. The hypothesis pointing to PIA as risk-lesion for prostate cancer has been extensively investigated at the cellular and molecular levels, but few morphological data are available linking PIA or prostatic intraepithelial neoplasia (PIN) to inflammation or clinical prostatitis. We investigated at the morphological level 1367 prostate biopsies from 98 patients with a recent history of chronic prostatitis, and 32 patients with biopsies positive for carcinoma. Our results show that i) PIA is found more frequently in biopsy cores containing a severe or moderate inflammatory focus, compared to NON-PIA lesions (partial or cystic atrophy); ii) the PIA lesion post-atrophic hyperplasia is more frequently found in tissues showing mild or no inflammation; iii) the extent of PIA per patient correlates with the burden of moderate or severe inflammation, whereas NON-PIA lesions do not; iv) low-grade PIN is in over 90% of cases emerging from normal, non-atrophic glands and is more frequently found in biopsy cores with absent or mild inflammatory burden; v) the inverse relationship between the prevalence of low-grade PIN and the extent of PIA lesions per patient is described by a power law function, suggesting the low likelihood of the concomitant presence of these lesions in the same tissue; vi) NON-PIA lesions correlate inversely with neoplasia in patients with prostate cancer; vii) the total scores of the NIH-CPSI questionnaire correlate with both PIA and inflammation burdens at diagnosis of prostatitis but not after pharmacological intervention. These results point to a positive association between tissue inflammation, clinical prostatitis and the putative cancer risk-lesion PIA, but do not support a model whereby low-grade PIN would arise from PIA.

Macrolides for the treatment of chronic bacterial prostatitis: an effective application of their unique pharmacokinetic and pharmacodynamic profile (Review)

Chronic bacterial prostatitis (CBP) is a persistent infection of the prostate characterized by poor quality of life mainly due to frequent relapse episodes caused by incomplete eradication of causative pathogens. Aggressive antibacterial therapy is required to attenuate the severe symptoms of CBP and to achieve a permanent cure. Although fluoroquinolones are currently recommended as first-choice agents, macrolide antibiotics are emerging as a noteworthy option for the treatment of CBP. Macrolide antibiotics are characterized by an impressive array of distinct pharmacokinetic (PK) and pharmacodynamic (PD) properties. These properties include high intracellular accumulation in phagocytes and at sites of infection, including the prostate; broad antibiotic but also biofilm-inhibiting properties; immunomodulating and inflammation-resolving activities. These features offer particular advantages for the treatment of chronic infections of the prostate gland, which are not easily amenable to drug therapy. Macrolides may be exploited to counteract the unsatisfactory rates of clinical symptom improvement and pathogen eradication. The results of a number of clinical trials support this proposal.

Characterization of the c.190T>C missense mutation in BRCA1 codon 64 (Cys64Arg)

In the Milan area (Northern Italy), we identified a family characterized by a high prevalence of ovarian and breast cancer cases (5 out of 6 subjects, over 3 generations), and a predominant prevalence of ovarian lesions (4 out of 5 patients). Analysis of BRCA1 and BRCA2 genes allowed the identification of the missense c.190T>C mutation in codon 64 (Cys64Arg) of BRCA1. The aims of the present investigation were to characterize the functional implications of the c.190T>C mutation at the molecular level, and to search whether additional polymorphisms might be linked to the peculiar phenotypic features observed in the Italian pedigree. Molecular modelling studies suggested that substitution of the cysteine 64 with an arginine likely disrupts the architecture of the BRCA1 RING finger domain, responsible for the interaction with BARD1, essential for the tumor-suppressor activity of the BRCA1-BARD1 complex. By splicing site information analysis, exonic splicing enhancer site characterization, and analysis of transcript fragment length and sequence, we showed that the c.190T>C mutation was able to modulate the splicing of exon 5 in a fashion opposite to the c.190T>G transversion, responsible for the functionally-related Cys64Gly amino acid substitution. Genotyping of BRCA1 and BRCA2 in the Italian family revealed the presence of two significant polymorphisms: the cancer-associated c.2612C>T SNP in BRCA1, and the c.-26G>A SNP in the BRCA2 gene, acting as an ovarian cancer risk modifier in carriers of deleterious BRCA1 mutations. Analysis of these SNPs in a genotypically-unrelated Polish family, characterized by prevalent breast neoplasms in carriers of the c.190T>C mutation, revealed a genetic profile consistent with the hypothetic role of both polymorphisms.

Enhanced distribution of fourth-generation fluoroquinolones in prostatic tissue

A recently published pharmacokinetic trial showed that the fluoroquinolone moxifloxacin administered to healthy volunteers at the single oral dose of 400mg accumulates in prostatic secretions (PS) up to a median concentration of 3.99 mg/L and reaches a PS/plasma concentration ratio of 1.57, far higher than values shown by other fluoroquinolones such as norfloxacin (ratio 0.1) or ciprofloxacin (ratio 0.2). Ion trapping mechanisms were hypothesised to be among the determinants of this effect. However, whether ion trapping would solely account for the observed differences in fluoroquinolone pharmacokinetics was left to further research and discussion. In this hypothesis paper, we review various published evidence on the tissue distribution of moxifloxacin and other quinolones, suggesting that increased lipophilicity, binding to cellular matrices and fast cellular uptake/release kinetics may be mechanisms compatible with enhanced prostatic accumulation and secretion of fourth-generation fluoroquinolones.

Anti-infective treatment of bacterial urinary tract infections

Bacterial urinary tract infections (UTI) are frequently found in the outpatient as well as in the nosocomial setting. The bacterial UTI can be stratified into uncomplicated and complicated UTI. Antibiotic resistance is continuously increasing in uncomplicated as well as complicated UTI. In uncomplicated UTI efforts are made to use antibiotic substances exclusively for this indication. In complicated UTI as broad spectrum antibiotics are increasingly used, the higher the antimicrobial resistance rates are reported. There are two predominant aims in the antimicrobial treatment of both uncomplicated and complicated UTI: 1.) rapid and effective response to therapy, prevention of complications and prevention of recurrence in the individual patient treated, and 2.) prevention of emergence of resistance to anti-infective agents in the microbial environment. The use of antibiotics has to keep up with the continuous change in antimicrobial resistance and the tailored needs in the individual patient. Antibiotic substances therefore need to become evaluated for each indication and continuously followed for clinical usage. The knowledge of structure-activity relationships of antimicrobial substances and bacterial resistance mechanisms to antibiotics help to use antibiotics better in daily routine and design new derivatives and substances. The aim of this review is to describe the chemistry and structure-activity relationships of current antibiotics and promising substances in development for the treatment of UTI.

5-Lipoxygenase and anandamide hydrolase (FAAH) mediate the antitumor activity of cannabidiol, a non-psychoactive cannabinoid

It has been recently reported that cannabidiol (CBD), a non-psychoactive cannabinoid, is able to kill glioma cells, both in vivo and in vitro, independently of cannabinoid receptor stimulation. However, the underlying biochemical mechanisms were not clarified. In the present study, we performed biochemical analysis of the effect of CBD both in vivo, by using glioma tumor tissues excised from nude mice, and in vitro, by using U87 glioma cells. In vivo exposure of tumor tissues to CBD significantly decreased the activity and content of 5-lipoxygenase (LOX, by approximately 40%), and of its end product leukotriene B4 ( approximately 25%). In contrast cyclooxygenase (COX)-2 activity and content, and the amount of its end product prostaglandin E2, were not affected by CBD. In addition, in vivo treatment with CBD markedly stimulated ( approximately 175%) the activity of fatty acid amide hydrolase (FAAH), the main anandamide-degrading enzyme, while decreasing anandamide content ( approximately 30%) and binding to CB1 cannabinoid receptors ( approximately 25%). In vitro pre-treatment of U87 glioma cells with MK-886, a specific 5-LOX inhibitor, significantly enhanced the antimitotic effect of CBD, whereas the pre-treatment with indomethacin (pan-COX inhibitor) or celecoxib (COX-2 inhibitor), did not alter CBD effect. The study of the endocannabinoid system revealed that CBD was able to induce a concentration-dependent increase of FAAH activity in U87 cells. Moreover, a significantly reduced growth rate was observed in FAAH-over-expressing U87 cells, compared to wild-type controls. In conclusion, the present investigation indicates that CBD exerts its antitumoral effects through modulation of the LOX pathway and of the endocannabinoid system, suggesting a possible interaction of these routes in the control of tumor growth.

Role in anxiety behavior of the endocannabinoid system in the prefrontal cortex

In the present study we explored with a multidisciplinary approach, the role of anandamide (AEA) in the modulation of anxiety behavior at the level of the prefrontal cortex (PFC). Low doses of the metabolically stable AEA analog, methanandamide, microinjected into the PFC, produced an anxiolytic-like response in rats, whereas higher doses induced anxiety-like behaviors. Pretreatment with the selective antagonist of CB1 or TRPV1 receptors (AM251 and capsazepine, respectively) suggested that the anxiolytic effect evoked by AEA might be due to the interaction with the CB1 cannabinoid receptor, whereas vanilloid receptors seem to be involved in AEA anxiogenic action. When AEA contents in the PFC were increased by microinjecting the selective inhibitor of fatty acid amide hydrolase (FAAH), URB597, we observed an anxiolytic response only at low doses of the compound and no effect or even an anxiogenic profile at higher doses. In line with this, a marked decrease of AEA levels in the PFC, achieved by lentivirus-mediated local overexpression of FAAH, produced an anxiogenic response. These findings support an anxiolytic role for physiological increases in AEA in the PFC, whereas more marked increases or decreases of this endocannabinoid might lead to an anxiogenic response due to TRPV1 stimulation or the lack of CB1 activation, respectively.

Growth Factors and Chemokines: A Comparative Functional Approach Between Invertebrates and Vertebrates

Growth factors and cytokines control and coordinate a broad spectrum of fundamental cellular functions, and are evolutionarily conserved both in vertebrates and invertebrates. In this review, we focus our attention on the functional phylogenetic aspects of growth factors/cytokines like the Transforming Growth Factor-beta (TGF-beta), the Connective Tissue Growth Factor (CTGF), and the Vascular Endothelial Growth Factor (VEGF). We will also delve into the activites of two chemokine families, interleukin (IL)-8 (or CXCL8) and CC chemokine ligand 2/monocyte chemoattractant protein-1 (CCL2). These molecules have been selected for their involvement in immune responses and wound healing processes, where they mediate and finely regulate various regeneration processes like angiogenesis or fibroplasia, not only in vertebrates, but also in invertebrates.

Distinctive cellular roles for novel protein kinase C isoenzymes

A number of in vitro studies have implicated protein kinase Cdelta (PKCdelta) and PKCepsilon in the regulation of the immune system. In recent years, this has been convincingly demonstrated in mice deficient for PKCdelta and PKCepsilon. The reported phenotypes for these transgenic mice indicate that PKCdelta suppresses immunoresponsiveness and inhibits the proliferation of B-lymphocytes, while PKCepsilon is required for macrophages to mount an effective immune response to bacterial pathogens. In either case, these isoenzymes appear to cooperate in fine-tuning certain immunoreactions by either suppressing (PKCdelta) or stimulating (PKCepsilon) the transcription of various cytokines. This review will compare and contrast the structures of these two nPKC isoenzymes and their respective roles in the modulation of cytokine production and various other cellular processes, such as growth, differentiation, apoptosis, and tumor suppression.

Hematopoietic cell formation in leech wound healing

The angiogenic process in vertebrates and hirudineans has been compared. The leech Hirudo medicinalis, subjected to an angiogenic stimulus (surgical explant or cytokine treatment) responds, as a vertebrate, with the formation of an extensive network of new vessels accompanied by the production of circulating cells. The reviewed data confirm the surprising similarity between hirudinean and vertebrate processes in wound healing, and suggest that basic common events such as antigenic expressions of endothelial and hemopoietic cells, cytokine secretion and regulation as well as extracellular matrix interactions, are conserved and extended across diverse species, tissues and developmental phases.

Structure and function of the extraembryonic membrane persisting around the larvae of the parasitoid Toxoneuron nigriceps

The embryo of Toxoneuron nigriceps (Hymenoptera, Braconidae) is surrounded by an extraembryonic membrane, which, at hatching, releases teratocytes and gives rise to a cell layer embedding the body of the 1st instar larva. This cell layer was studied at different developmental times, from soon after hatching up to the first larval moult, in order to elucidate its ultrastructural, immunocytochemical and physiological function. The persisting "larval serosa" shows a striking structural and functional complexity: it is a multifunctional barrier with protective properties, limits the passage of macromolecules and it is actively involved in the enzymatic processing and uptake of nutrients. The reported results emphasizes the important role that the embryo-derived host regulation factors may have in parasitism success in Hymenoptera koinobionts.

Hirudo medicinalis: a new model for testing activators and inhibitors of angiogenesis

An increasing body of evidence indicates that in the leech Hirudo medicinalis the angiogenic process is finely regulated and coordinated by the botryoidal tissue. In this paper we provide evidence on the involvement of botryoidal tissue cells in angiogenesis induced in H. medicinalis by a variety of stimuli including surgical wounds or the administration of modulators of neovascularization. Interestingly, we show that either human activators of vascular cell growth, or anti-angiogenic peptides like angiostatin and endostatin, or the drug mitomycin, can induce a prompt biological response in H. medicinalis. We show as well that angiogenesis in this invertebrate shares a surprising degree of similarity with neovascularization in vertebrates, both at the biochemical and cellular levels, because it involves similar growth factors/growth factor receptors, and relies on analogous cell-cell or cell-matrix interactions. For these reasons we suggest that H. medicinalis can be used as a reproducible model for testing activators or inhibitors of angiogenesis, and for investigating the biochemical, ultrastructural and cellular processes involved in new vessel formation.

Involvement of PI3K in PKCepsilon-mediated oncogenic signal in rat colonic epithelial cells

We have recently demonstrated that overexpression of PKCepsilon is oncogenic in colonic epithelial cells. To test whether PI3K might be an upstream effector of PKCepsilon in cell transformation, we have overexpressed the p110alpha PI3K subunit in non-transformed D/WT colonic epithelial cells. Transfectants displayed the major in vitro features of transformed cells. Interestingly, no transformation occurred when p110alpha was co-transfected with a dead-kinase PKCepsilon mutant. The p85alpha subunit of PI3K, displaying a dominant-negative-like effect, was then transfected in PKCepsilon-transformed D/epsilon cells. The transformed profile of these cells was markedly reduced. To identify which by-products of PI3K might be involved in cell transformation we have transfected the D/WT cell line with cDNAs encoding the PI3 kinases hVps34 and C2beta. Overexpression of hVps34 did not cause cell transformation. Conversely, in vitro transformation was observed when C2beta was transfected into D/WT cells. These results indicate that phosphatidylinositol-3 monophosphate does not seem to be involved in cell transformation, and that phosphatidylinositol-3,4 bisphosphate and phosphatidylinositol-3,4,5 trisphosphate are more likely involved in this process. Thus, our data support the hypothesis of a linkage between PI3K and PKCepsilon, and indicate that PI3K may act as a source of second messengers responsible for oncogenic activation of PKCepsilon.

Resistance of human leukemic cell lines to 1-beta-D-arabinofuranosylcytosine: characterization of an experimental model

1-beta-D-arabinofuranosylcytosine (ara-C) is an antimetabolite used for the treatment of acute myelogenous leukemia. The ability of ara-C to kill neoplastic cells has been correlated to the induction of apoptosis. The clinical use of ara-C is limited by the development of drug resistance. Alterations in drug-induced apoptosis play a critical role in ara-C resistance. In particular, the proto-oncogene bcl-2 has been implicated in this phenomenon. To better understand the molecular basis of the role of bcl-2 in ara-C resistance, we investigated the relationship between the cytotoxic effect of ara-C, the expression levels and the subcellular localization of bcl-2 in three human leukemic cell lines (HL-60, KG1, J111). We have also evaluated the effects of ara-C on the J111 leukemic cell line (showing the lowest levels of Bcl-2 and the highest sensitivity to ara-C) overexpressing the bcl-2 oncogene. The model we developed here will allow further studies on the role of post-translational events involving bcl-2 (such as translocation and/or phosphorylation) in the cellular response to ara-C treatment.

Antitumor activity of endostatin against carcinogen-induced rat primary mammary tumors

Endostatin, a Mr 20,000 fragment of collagen XVIII, potently inhibits the growth of experimental tumors implanted in mice. Here we report the cloning, expression, and antitumor activity of the rat form of endostatin. When tested on breast carcinomas arising in female virgin rats after intragastric administration of 9,10-dimethyl-1,2-benzanthracene (DMBA), endostatin induced significant inhibition of mammary tumor growth in all of the treated rats during a 4-week treatment period without signs of systemic toxicity. Interestingly, this arrest of tumor growth persisted throughout a four-week off-therapy period. Moreover, endostatin was effective in counteracting the development of multiple primary tumors. These results confirm that rat endostatin is a potent anticancer agent in a carcinogen-induced, spontaneously arising rat breast cancer model. It not only stops the growth of existing tumors but also decreases the incidence of the development of multiple neoplastic lesions.

PKCs

Molecular cloning and biochemical characterization of individual members of the protein kinase C (PKC) family demonstrated that single PKC isoenzymes display distinct structure, activation conditions, substrate specificity and tissue distribution. In the last few years a number of studies based on isoenzyme overexpression indicated that the PKC family coordinates a complex network of pivotal signal transduction pathways and pathway crosstalks, which regulate cell growth and differentiation, neoplastic transformation and malignant progression. This study reviews recent progress in PKC investigation, and focuses on achievements which have been shown to be relevant to cancer research.

Epsilon PKC acts like a marker of progressive malignancy in rat liver, but fails to enhance tumorigenesis in rat hepatoma cells in culture

We have analyzed the expression pattern of epsilon protein kinase C (PKC) in normal liver tissue, in hyperplastic liver nodules and in hepatocellular carcinomas generated in the rat with the Solt-Farber protocol. A progressive increase in PKC epsilon expression was observed in nodules and carcinomas compared to normal liver tissue, suggesting that the expression level of this PKC isoenzyme could be associated with increased malignancy. To test this hypothesis, the well differentiated, poorly tumorigenic MH1C1 rat hepatoma cell line was stably transfected with a full length epsilon PKC cDNA. No increase in growth rate, saturation density, soft agar growth or in vivo tumorigenicity was observed in transfected cells, compared to parental or mock-transfected cells. These results indicate that epsilon PKC does not seem to participate in signaling pathways involved in neoplastic transformation or malignant progression in our liver cell model. The fact that epsilon PKC overexpression is tumorigenic in several other cell types suggests that this effect might be strictly cell- and tissue-specific.

Differential phorbol ester growth modulation and protein-kinase-C isoenzyme expression in rat hepatoma-cells vs non neoplastic rat hepatocytes

In the present study the expression of protein kinase C (PKC) isoenzymes and the growth modulation caused by phorbol esters were studied in two rat hepatic cell lines: the neoplastic MH1C1 hepatoma and the syngeneic immortalized non-neoplastic BRL3A cell line. Western blot analysis revealed that MH1C1 rat hepatoma cells express the a isoenzyme as the only isoform of PKC, whereas BRL3A cells showed immunoreactivity for alpha, delta and epsilon PKC. Immunoblot analysis showed that in both cell lines phorbol 12-myristate 13-acetate (PMA) caused a persistent, marked down-regulation of all expressed PKC isoenzymes. In MH1C1 cells, PMA also induced a reversible, marked dose-dependent growth inhibition, whereas a minimal impairment of cell proliferation was observed in BRL cells. The observed selective mitoinhibitory effect of PMA on tumor cells indicates PKC as an interesting target for innovative antiproliferative strategies based on the modulation of specific isoenzymes.

Analysis of calcium-dependent protein kinase-C isoenzymes in intrinsically resistant cloned lines of LoVo cells: reversal of resistance by kinase inhibitor 1-(5-isoquinolinylsulfonyl) 2-methylpiperazine

In order to investigate the involvement of Protein Kinase C (PKC) in the signal transduction mechanisms related to intrinsic chemoresistance, two cellular clones were isolated from LoVo/WT colon adenocarcinoma cell line and their cytogenetic pattern was studied: LoVo C1.7 was intrinsically resistant to Doxorubicin while LoVo C1.5 showed the same resistance index as the mixed parental cell population. Two PKC isoforms, immunologically identified as beta and alpha PKC, were isolated from the cytosolic fraction of all cell types and one single peak of alpha PKC was obtained from the particulate fraction. Resistant LoVo C1.7 cells showed a significant increase of PKC activity; preincubation with H-7 induced PKC inhibition and reversal of drug resistance. These data suggest that in our cell system the identified calcium-dependent PKC subtypes can play a role in the mechanisms of intrinsic resistance.

Cardiotoxicity induced by doxorubicin in vivo: protective activity of the spin trap alpha-phenyl-tert-butyl nitrone

The role of free radical generation in the development of the acute cardiotoxicity induced by doxorubicin (DXR) in the rat and the protective activity of anti-radical drugs were investigated in in vivo experiments by evaluating the body weight curve, ECG, contractile performance and coronary flow up to 10 days after DXR. A lipophilic spin trap (alpha-phenyl-tert-butyl nitrone, PBN) was continuously administered at a dose of 0.65 mg/kg every hour for 2 weeks by an intraperitoneal osmotic pump. DXR was administered i.v. at a dose of 9 mg/kg 3 days after beginning the PBN infusion. DXR impaired ECG and body weight gain after 3 days (partly reversible at later times), while contractility and coronary flow were significantly impaired throughout the experimental time. PBN was shown to prevent the DXR-induced alterations of contractility and coronary flow, while ECG was non-significantly improved. The body weight curve was not affected. Since the dose of PBN used does not produce pharmacological effects, the protective activity in rats receiving DXR indicates that free radicals may play a causal role in the acute cardiotoxicity in vivo. The use of suitable spin traps and administration schedules seems to be an interesting approach for the prevention of radical-dependent pathologies.

The activity of a beta subtype of protein kinase C purified from nuclei of human neutrophils is enhanced by treatment with phorbol 12-myristate 13-acetate

Two protein kinase C isoenzymes were partially purified from the nuclei of human neutrophils, and identified as beta and alpha subtypes. Treatment of neutrophils with phorbol 12-myristate 13-acetate (PMA) caused a 3.8-fold increase of nuclear beta PKC activity, while a minor increase of alpha PKC was observed. This selective activation of beta PKC could help to understand the molecular events involved in phorbol ester-induced cellular modifications.

Protective effects of spin-trapping agents on adriamycin-induced cardiotoxicity in isolated rat atria

Adriamycin (ADR) is known to exert a severe negative inotropic effect on isolated myocardial preparations; a role for free radical generation has been hypothesized. Spin-trapping of free radicals has been extensively exploited in ESR studies, both in cell-free systems and in intact tissues. The interaction between spin-traps and free radicals should in principle stop the reaction cascade leading to cellular damage. Based on this hypothesis, the possible cardioprotective action of three spin-trapping agents, 5,5-dimethyl-l-pyrroline-N-oxide (DMPO), N-tert-butyl-alpha-phenylnitrone (PBN) and alpha-(4-pyridyl 1-oxide) N-tert-butylnitrone (POBN), was tested on isolated rat atria incubated in the presence of ADR; maximal non-cardiotoxic concentrations were used (50, 10 and 50 mM respectively) in order to achieve a maximal spin-trapping effect. A varying degree of protection was observed with the three compounds, directly correlated to their hydrophobicity, as assessed by chloroform/water partition coefficients. It is proposed that ADR-induced free radical generation is responsible for the acute cardiotoxic effects of the drug; this seems to be a site-specific mechanism restricted to one or more hydrophobic cellular compartment/s, since only lipophilic spin-trapping agents are able to prevent the development of the negative inotropic effect of ADR.

A new approach to the direct detection of free radicals in the intact myocardium

A new method for the direct ESR detection of free radicals in rat myocardial tissue is described. Isolated rat atria are continuously monitored for heart rate and contractile force; at the end of the experimental period the beating organs are inserted into quartz ESR tubes and immediately frozen in liquid nitrogen. Spectra obtained from these preparations show the presence of very weak radical signals. When ESR spectra are recorded on samples obtained from pools of rat atria pulverized under liquid nitrogen, the radical lines are markedly stronger than those observed for intact organs; contaminating metals are also frequently detected. These findings indicate that crushing or grinding procedures carried out under liquid nitrogen produce artifactual ESR active species. The new method described in the present paper does not involve mechanical interventions and therefore should yield reliable artifact-free results.

Effect of trimetazidine on early and delayed doxorubicin myocardial toxicity

The influence of the administration of trimetazidine on the myocardial toxicity induced by doxorubicin was studied on an in vivo model in the rat. Trimetazidine was chosen due to its ability to act as a scavenger of oxygen-derived free radicals, which have been implicated in both early and delayed cardiotoxic manifestations after doxorubicin treatment. In the present study, doxorubicin was administered as 4 weekly i.v. injections of 3 mg/kg. The cardiotoxic effects were evaluated by measuring predictive ECG parameters (QT and ST intervals) as well as the contractile performance of atria isolated from treated animals. Heart preparations were also examined by light microscopy. Trimetazidine, 2.5 mg/kg/day i.p. for 3 days before doxorubicin administration plus 2.5 mg/kg/day p.o. for 10 weeks, was unable to prevent the development of doxorubicin-induced long-term cardiotoxicity. However, a significant improvement of the early cardiotoxic signs was observed in trimetazidine-treated rats, as reported in previous investigations. The present findings suggest that different target structures may be involved in the early and delayed free radical-mediated effects of doxorubicin.

Hypoxia as a risk factor for doxorubicin-induced cardiotoxicity: a NMR evaluation

Previous studies suggested that one possible mechanism of doxorubicin (DXR)-induced cardiomyopathy involves the depletion of high-energy phosphate stores. In this study, we used 31P nuclear magnetic resonance to assess the high-energy phosphate content in Langendorff perfused rat hearts. Hearts were perfused in normoxic conditions (spontaneous flow) or in partially hypoxic conditions obtained by perfusing at 50% of the spontaneous flow. DXR was used at the subtoxic conditions of 50 mg/l for 15 min and at the cardiotoxic concentration of 100 mg/l for 60 min. Left ventricular pressure (dP/dt), heart rate, myocardial ATP and PCr levels and PCr/ATP ratio were measured. We found that, in normoxic conditions, DXR (50 mg/l, 15 min) does not impair cellular high-energy phosphate metabolism. However, in mild hypoxic conditions, DXR induces a significant decrease in PCr/ATP ratio, due to a decrease in PCr and to a simultaneous increase in ATP. Similar results are obtained after 60 min perfusion with the cardiotoxic dose of DXR. This study suggests that hypoxia may represent a risk factor for the development of DXR-induced acute cardiotoxicity.