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Objectives: The symptoms of herpes simplex viruses type 1 (HSV‐1) infections might be severe and persistent in immunocompromised patients in whom they reactivate at a high frequency. The development of Acyclovir (ACV) resistant strains due to long‐term treatment with antiviral agents in those patients is not uncommon. The aim of the present study was to assess the virucidal effect of commercially available mouthwashes against ACV‐resistant HSV‐1 strains. Materials and Methods: Two acyclovir‐resistant HSV‐1 strains were exposed for 30 s to essential oil‐based (Listerine Fresh Burst® and Listerine Zero®), chlorhexidine gluconate 0.2% (Hexidyl®) and povidone‐iodine 7.5% (Betadine Gargle®) mouthwashes. Loss of virus infectivity was determined by means of plaque reduction assays in a cell culture system. Results: All 4 of the tested solutions significantly reduced virus infectivity, with the essential oil‐based and povidone‐iodine mouthwashes being slightly more efficacious, compared to chlorhexidine. Conclusion: The findings of this analysis revealed that the tested oral rinses demonstrated in‐vitro antiviral activity against ACV‐resistant HSV. Comparative clinical trials are required to establish the clinical effectiveness of daily use of oral rinses in reducing the appearance of oral HSV lesions in immunocompromised patients. [ABSTRACT FROM AUTHOR]

The herpes simplex viruses consist of the strains, HSV-1 and HSV-2, which are prevalent worldwide and lack a definitive cure. We aimed to explore the specific characteristics of HSV 1 and 2 infections, such as differences between gender assigned at birth, age at infection, site of infection, comorbidities, and effect of pregnancy, through a data analysis. Between 2011 and 2018, the Israeli Central Virology Laboratory diagnosed 9189 samples using multiplexed real-time PCR. In addition, we extracted all of the medical data for 287 females hospitalized at the Sheba Medical Center with HSV-1 (161) or HSV-2 (126) genital infections. HSV-2 was almost absent in the orofacial samples from both genders, while in other lesion sites, HSV-2 was significantly more abundant in females than in males ( p < 0.05,). HSV-2 was initially detected at puberty. In the hospitalized females' malignancies, both HSV-1 and HSV-2 were found with a non-significant difference. Simultaneously, pregnancies were more common in females who were HSV-2-positive compared with those who were HSV-1-positive (27.8% vs. 12.4%, respectively, p < 0.01). Primary infections occur more with HSV-1 than with HSV-2 (15.6% vs. 3.2%, respectively). Our findings demonstrate that genital HSV-2 infection episodes are more frequent during pregnancy, suggesting that pregnancy may serve as a risk factor for HSV-2 reactivation or infection.

Background: Early reports described an increased risk of herpes zoster following receipt of mRNA-based COVID-19 vaccines. The objective was to assess whether COVID-19 vaccine is associated with varicella-zoster virus-induced neurologic disease (VZV-ND)., Methods: This multicenter retrospective case-control study with a test-negative design was conducted at 12 hospitals in Israel. We included all patients admitted with VZV-ND between January 2020 and December 2021 and matched controls with a negative polymerase chain reaction result for VZV in cerebrospinal fluid., Results: We identified 188 patients meeting the case definition of VZV-ND who were admitted during the study period. Cases were matched with 376 controls. There was no significant variation in the incidence of VZV-ND between 1 year preceding and 1 year following the deployment of BNT162b2 in Israel. Analysis of persons who had received at least 1 dose of COVID-19 vaccine (n = 259) showed similar proportions of VZV-ND and non-VZV-ND in 4 intervals (30, 42, 50, 60 days) following the last vaccine dose. The median time from the last vaccine dose to hospitalization with a neurologic syndrome was 53 days (IQR, 25-128) and 82 days (IQR, 36-132) for VZV-ND and non-VZV-ND, respectively, not reaching statistical significance ( P = .056). The rate of VZV-ND in vaccinated patients was no different from the rate in the unvaccinated group (30.9% vs 35.4%, P = .2)., Conclusions: We did not find an association between COVID-19 vaccine and VZV-ND. Since COVID-19 vaccine is now recommended yearly, every fall and winter, establishing the safety of the vaccine is of great importance., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background and Aims: An increase in the number of cases of acute hepatitis of unknown origin (HUO) in children was observed in 2021. Adenovirus and adeno-associated virus 2 (AAV2) infections have been suggested as possible triggers. However, the potential etiology is still unclear. We aimed to characterize a cohort of children with HUO in Israel in view of the COVID-19 pandemic., Method: Demographics, clinical data, and laboratory results on the children compatible with the CDC criteria for HUO were collected by the established registry of the Ministry of Health. Available specimens were sent to the Central Virology Laboratory., Results: A total of 39 children were included in the registry. A total of 20 were enrolled prospectively, in which human herpes virus 6 (HHV6) infection or reactivation was identified in 11/19, adenovirus was found in 4/19 of the cases, and AAV2 was detected in 2/16. Past COVID-19 exposure was recorded for 24/39 of the children. A total of 10 children underwent liver biopsy, and 8 were successfully treated with steroids and 2 underwent liver transplantation., Conclusions: The COVID-19 pandemic and the related containment measures combined with reactivation or active infection with other viruses could have been a trigger for the HUO outbreak. In our cohort, HHV6 was the most abundant finding.

Background: Varicella zoster virus (VZV) is among the leading pathogens causing meningitis and encephalitis. While VZV-PCR-positive CSF is considered a gold-standard for diagnosis, it is not-uncommon to detect VZV-DNA in CSF of patients with other acute or chronic illness. Our goal was to determine the clinical relevance of VZV-PCR-positive CSF when investigating patients with neurological symptoms., Methods: In this retrospective cohort from the largest hospital in Israel, we collected demographic, clinical and laboratory data of patients with VZV-PCR-positive CSF, analyzing the significance of various parameters., Results: During a 5-years study, 125 patient-unique VZV-PCR-positive CSFs were recorded, in which only 9 alternative diagnoses were noted. The commonest symptoms were headache (N = 104, 83 %) and rash (N = 96, 76 %). PCR-cycle-threshold (Ct), a surrogate of viral burden, did not significantly vary across the clinical manifestations; however, patients with rash and Ct<35 were prone to develop stroke in the following year (N = 6, 7 %). Empiric nucleoside-analogue treatment was not associated with a better outcome compared to treatment administered upon a positive-PCR result., Discussion: Our findings suggest that in patients with neurological symptoms, detection of VZV-DNA in CSF renders VZV the probable culprit. Nevertheless, a systematic evaluation of treatment and follow-up algorithms of patients with suspected or proved VZV meningitis and encephalitis is needed. The benefits of a prompt treatment should be weighed against the potential complications of nucleoside-analogue. Conversely, the propensity for stroke in patients with higher viral-burden, necessitates further studies assessing VZV causal role, directing additional workup, treatment and monitoring policy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Herpes Simplex Virus (HSV) type 1 (HSV-1) and type 2 (HSV-2) are among the most common human viral pathogens, affecting several billion people worldwide. Although in healthy patients clinical signs and symptoms of HSV infection are usually mild and self-limiting, HSV-infections in immunocompromised patients are frequently more aggressive, persistent, and even life-threatening. Acyclovir and its derivatives are the gold standard antiviral drugs for the prevention and treatment of HSV infections. Although the development of acyclovir resistance is a rather uncommon condition, it may be associated with serious complications, especially in immunocompromised patients. In this review, we aim to address the problem of drug resistant HSV infection and discuss the available alternative therapeutic interventions. All relative studies concerning alternative treatment modalities of acyclovir resistant HSV infection published in PubMed between 1989 to 2022 were reviewed. Long-term treatment and prophylaxis with antiviral agents predisposes to drug resistance, especially in immunocompromised patients. Cidofovir and foscarnet could serve as alternative treatments in these cases. Although rare, acyclovir resistance may be associated with severe complications. Hopefully, in the future, novel antiviral drugs and vaccines will be available in order to avoid the existing drug resistance., (© 2023 The Authors. Oral Diseases published by Wiley Periodicals LLC.)

Pemphigus vulgaris is a rare autoimmune skin disease. Although herpes simplex virus has been associated with autoimmune diseases, evidence regarding its association with pemphigus vulgaris exacerbations is scarce. This retrospective cohort study aimed to characterize the epidemiological and clinical features of patients with pemphigus vulgaris who were herpes simplex-positive, compared with those who were herpes simplex-negative, during disease onset. Of 62 patients with pemphigus vulgaris who underwent PCR testing for herpes simplex virus, 25 (40.3%) were positive, with a mean age of 56.1 ± 15.5 years; 35.5% were male. The herpes-positive group had significantly elevated levels of C-reactive protein, Pemphigus Disease Activity Index score, and shorter time to relapse. The time to remission, number of exacerbations per year, and remission status were non-significantly elevated in the herpes-positive group. Thus, routine testing lesions from patients with pemphigus for herpes simplex virus should be performed. If positive, antiviral treatment should be initiated; and preventive antiviral treatment should be considered in severe cases.

Background: Infections in neonates with herpes simplex virus 1 (HSV-1) following circumcision due to Metzitzah Be'Peh (MBP) performed by a Mohel occur each year in small numbers. One solution to this problem is the use of a mucus extractor device instead of MBP, which has been authorized by some rabbis. Yet, using a mucus extractor remains controversial among ultra-Orthodox Jews; thus, creating a need for additional solutions., Objectives: To seek to reduce HSV-1 infection of neonates due to MBP., Methods: We tested several oral rinse solutions for their ability to destroy virus infectivity following incubation for 30 seconds and using plaque reduction assays., Results: Corsodyl, Decapinol, and Listerine® all destroyed plaques formation of spiked virus, while Gengigel and Tantum Verde were found to be less effective. We focused specifically on Listerine® due to its efficacy in eliminating contagious HSV-1 from saliva after a 30-second oral rinse. Five different products of Listerine® reduced the infectivity of a spiked virus by more than 4 orders of magnitude in 30 seconds. We also showed that Listerine (up to 7% v/v) can stay in the mouth but did not harm living cells and therefore will not cause any damage to the injured tissue., Conclusions: Significant reduction in cases of infection with HSV-1 due to MBP can be achieved if Mohalim consistently adopt the practice of careful mouth washing with Listerine® just before performing MBP.

Varicella live attenuated vaccine led to a significant reduction in morbidity and mortality from varicella zoster disease. Vaccine adverse effects are mostly mild. Immunosuppression is the main risk factor for severe varicella. Risk factors for disease following vaccination are less studied. We report a 12-month-old infant with no T-cell immunodeficiency who developed severe varicella infection by vaccine strain.

Data regarding presentation and management of human herpes virus 6 (HHV-6) reactivation among autologous hematopoietic cell transplantation (HCT) recipients are limited. We retrospectively reviewed medical charts of all autologous HCT patients tested for HHV-6 reactivation due to suspected clinical presentation between 1/2012 and 8/2017. Among 328 autologous HCT recipients, 44 patients were tested for HHV-6 reactivation. Thirty patients tested positive; 29 (97%) had sustained fever, six (20%) had rash and four (13%) had pneumonia. Median C-reactive protein was significantly lower in HHV-6 positive patients compared to negative patients (3.6 (range, 0.4-11) vs. 9.6 (range, 3.2-30) mg/dL, respectively, p  = .004). Ganciclovir formulations were administrated in 29 (97%) patients with median time to fever resolution of one (range, 1-2) day. HHV-6 should be considered as an important cause of post engraftment fever in autologous HCT. Larger studies are warranted to evaluate incidence of HHV-6 reactivation and optimal treatment regimen.

Background: In recent years, liver transplantation (LT) has become a well-accepted therapeutic modality for children with end-stage liver disease, with transplantation surgery being performed at a younger age. Human herpes virus 6 (HHV-6) infection occurs in most children within the first 2 years of life, therefore, data on primary HHV-6 infection in pediatric liver transplant recipients is scarce., Objective: To describe the course of primary HHV-6 infection after pediatric LT., Methods: Medical files, between the years 2015-2016, of post-LT pediatric patients with suspected primary HHV-6 infection were reviewed. Clinical and laboratory data for enrolled cases were evaluated. Primary infection was defined as DNAemia in children who were seronegative prior to transplantation or seroconversion from negative to positive IgG posttransplantation., Results: Four cases of primary HHV-6 (type B) infection were identified among the 26 children who had undergone LT at our center during the study period. All patients were <1 year old and presented with fever, hepatitis, and elevated inflammatory markers, most (75%) within a short-period posttransplantation. All were initially treated with empiric antibiotics for a suspected bacterial infection and three underwent liver biopsy, one showing signs of rejection. Three were treated with antiviral therapy with a gradual resolution of symptoms., Discussion: Primary HHV-6 should be taken into account in young children shortly after LT, especially when presenting with fever and elevated liver enzymes. Treatment with antiviral therapy should be considered., Conclusions: In young infants post-LT, a high index of suspicion may promote early detection of HHV-6 primary infection and prevent serious complications., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The Herpesviridae family consists of eight viruses, most of which infect a majority of the human population. One of the less-studied members is human herpesvirus 6 (HHV-6) (Roseolovirus), which causes a mild, well-characterized childhood disease. Primary HHV-6 infection is followed by lifelong latency. Reactivation frequently occurs in immunocompromised patients, such as those suffering from HIV infection or cancer or following transplantation, and causes potentially life-threatening complications. In this study, we investigated the mechanisms that HHV-6 utilizes to remain undetected by natural killer (NK) cells, which are key participants in the innate immune response to infections. We revealed viral mechanisms which downregulate ligands for two powerful activating NK cell receptors: ULBP1, ULBP3, and MICB, which trigger NKG2D, and B7-H6, which activates NKp30. Accordingly, this downregulation impaired the ability of NK cells to recognize HHV-6-infected cells. Thus, we describe for the first time immune evasion mechanisms of HHV-6 that protect lytically infected cells from NK elimination., Importance: Human herpesvirus 6 (HHV-6) latently infects a large portion of the human population and can reactivate in humans lacking a functional immune system, such as cancer or AIDS patients. Under these conditions, it can cause life-threatening diseases. To date, the actions and interplay of immune cells, and particularly cells of the innate immune system, during HHV-6 infection are poorly defined. In this study, we aimed to understand how cells undergoing lytic HHV-6 infection interact with natural killer (NK) cells, innate lymphocytes constituting the first line of defense against viral intruders. We show that HHV-6 suppresses the expression of surface proteins that alert the immune cells by triggering two major receptors on NK cells, NKG2D and NKp30. As a consequence, HHV-6 can replicate undetected by the innate immune system and potentially spread infection throughout the body. This study advances the understanding of HHV-6 biology and the measures it uses to successfully escape immune elimination., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

The current diagnosis of West Nile virus (WNV) infection is primarily based on serology, since molecular identification of WNV RNA is unreliable due to the short viremia and absence of detectable virus in cerebrospinal fluid (CSF). Recent studies have shown that WNV RNA can be detected in urine for a longer period and at higher concentrations than in plasma. In this study, we examined the presence of WNV RNA in serum, plasma, whole-blood, CSF, and urine samples obtained from patients diagnosed with acute WNV infection during an outbreak which occurred in Israel in 2015. Our results demonstrate that 33 of 38 WNV patients had detectable WNV RNA in whole blood at the time of diagnosis, a higher rate than in any of the other sample types tested. Overall, whole blood was superior to all other samples, with 86.8% sensitivity, 100% specificity, 100% positive predictive value, and 83.9% negative predictive value. Interestingly, WNV viral load in urine was higher than in whole blood, CSF, serum, and plasma despite the lower sensitivity than that of whole blood. This study establishes the utility of whole blood in the routine diagnosis of acute WNV infection and suggests that it may provide the highest sensitivity for WNV RNA detection in suspected cases., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Aberrant activation of the canonical Wnt signal transduction pathway is involved in a large number of human diseases. β-catenin, the key effector protein of the canonical Wnt pathway, functions in the nucleus with T-cell factor/lymphoid enhancer factor (TCF/LEF) to activate expression of Wnt target genes. Here we show that members of the 14-3-3 protein family bind disheveled-2 (Dvl-2) and glycogen synthase-3β (GSK-3β) to attenuate the interaction between GSK-3β and β-catenin. Importantly, 14-3-3 and β-catenin form "bleb-like" structures and are secreted via extracellular vesicles to induce Wnt signaling activity in target cells. Our data suggest a novel way of transducing the oncogenic Wnt signal in which β-catenin is regulated by 14-3-3ζ through the formation of "oncosomes" that contain both the 14-3-3 and β-catenin proteins., (Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)

Aim: Viral pneumonia is a serious complication in immunocompromised children. Its aetiology is difficult to identify owing to the limitations of conventional microbiological tests. The aim of this study was to determine whether polymerase chain reaction (PCR) assays for respiratory viruses increase the diagnostic yield of bronchoalveolar lavage (BAL) in immunocompromised children., Methods: BAL samples obtained from immunocompromised children hospitalized with pneumonia were processed for respiratory viruses by viral culture, rapid antigen test and PCR (for CMV, adenovirus, influenza, parainfluenza, herpesvirus, RSV and hMPV)., Results: The study group included 42 patients (mean age 7.2 ± 5.1 years) with 50 episodes of clinical pneumonia (50 BAL samples). Forty viral pathogens were identified in 30 episodes (60%). PCR increased the diagnostic rate by fourfold (75% identified by PCR alone, p < 0.0001). When viral culture and rapid antigen test were used as the gold standard, PCR was found to have high sensitivity (86-100% when assessed) and specificity (80-96%). The PCR results prompted the initiation of specific antiviral therapy and the avoidance of unnecessary antibiotic treatment in 17 (34%) episodes., Conclusion: PCR-based diagnosis from BAL may increase the rate of pathogen detection in immunocompromised children, decrease the time to diagnosis and spare patients unnecessary antimicrobial treatment., (©2013 Foundation Acta Paediatrica. Published by Blackwell Publishing Ltd.)

Background: The introduction of polymerase chain reaction (PCR) for the diagnosis of herpesvirus central nervous system infections is reshaping our understanding of these illnesses. Varicella-zoster virus (VZV) is increasingly recognized as an important etiology of sporadic viral meningoencephalitis (ME). Furthermore, mild cases of herpes simplex virus (HSV) ME, traditionally considered a devastating infection, are frequently reported., Methods: We compared the demographic and clinical features of patients with VZV (20) and HSV (17) ME diagnosed by Real-Time PCR of cerebrospinal samples in a single center during the years 2002-2010., Results: VZV and HSV patients were comparable with respect to age, sex, underlying diseases, immune suppression, and the rates of fever, headache and altered mental status on presentation. Seizures, focal neurological signs, systemic complications and in-hospital death were noted only in the HSV group., Conclusions: Our study confirms the prevalence of VZV as a cause of sporadic ME over the last decade. While patients with HSV ME had more manifestations of severe disease, there also was a significant overlap with clinical and laboratory parameters of VZV ME. In the absence of dermatomal rash, differentiation between VZV and HSV ME on clinical grounds alone may represent a true challenge., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Malignant melanoma is a highly aggressive tumor which frequently resists chemotherapy, therefore, the search for new agents for its treatment is of great importance. In this study, we purified the sesquiterpene lactones (SLs), Tomentosin and Inuviscolide from Inula viscosa (Compositae) leaves and studied their anti-cancer potency against human melanoma cell lines in order to develop new agents for melanoma treatment. SLs inhibited the proliferation of three human melanoma cell lines: SK-28, 624 mel and 1363 mel in a dose-dependent manner. We further investigated SLs mechanism of action using SK-28 as a representative cell line model. SLs caused cell-cycle arrest at G(2)/M, accompanied by the appearance of a sub-G0 fraction, indicative of apoptotic cell death. Induction of apoptosis was further confirmed by changes in membrane phospholipids, changes in mitochondrial membrane potential (DeltaPsi) and by detection of Caspase-3 activity. Rapid inhibitory phosphorylation of Cdc2 (Thr14 and Tyr15) was seen early after treatment, followed by a later decrease in the expression level of both Cyclin b1 and Cdc2. Induction of p53 and p21(waf1) proteins and phosphorylation of p53 at Ser15 were also detected early after treatment. The anti-apoptotic proteins, p65 subunit of nuclear factor kappaB (NF-kappaB), and Survivin were reduced in a dose-dependent manner. Taken together, these changes partially explain the ability of the SLs to induce G(2)/M arrest and apoptosis. Induction of apoptosis by Tomentosin and Inuviscolide in human aggressive melanoma cell lines has high pharmacological value and implies that SLs might be developed as new agents for melanoma treatment.

Our aim was to study the effects of cucurbitacin glucosides extracted from Citrullus colocynthis leaves on human breast cancer cell growth. Leaves were extracted, resulting in the identification of cucurbitacin B/E glucosides. The cucurbitacin glucoside combination (1:1) inhibited growth of ER(+) MCF-7 and ER(-) MDA-MB-231 human breast cancer cell lines. Cell-cycle analysis showed that treatment with isolated cucurbitacin glucoside combination resulted in accumulation of cells at the G(2)/M phase of the cell cycle. Treated cells showed rapid reduction in the level of the key protein complex necessary to the regulation of G(2) exit and initiation of mitosis, namely the p34(CDC2)/cyclin B1 complex. cucurbitacin glucoside treatment also caused changes in the overall cell morphology from an elongated form to a round-shaped cell, which indicates that cucurbitacin treatment caused impairment of actin filament organization. This profound morphological change might also influence intracellular signaling by molecules such as PKB, resulting in inhibition in the transmission of survival signals. Reduction in PKB phosphorylation and inhibition of survivin, an anti-apoptosis family member, was observed. The treatment caused elevation in p-STAT3 and in p21(WAF), proven to be a STAT3 positive target in absence of survival signals. Cucurbitacin glucoside treatment also induced apoptosis, as measured by Annexin V/propidium iodide staining and by changes in mitochondrial membrane potential (DeltaPsi) using a fluorescent dye, JC-1. We suggest that cucurbitacin glucosides exhibit pleiotropic effects on cells, causing both cell cycle arrest and apoptosis. These results suggest that cucurbitacin glucosides might have therapeutic value against breast cancer cells.

The JAK-STAT signal transduction cascade participates in various cellular processes, including immune response, cell replication, differentiation and oncogenesis. Here, we report that this cascade is induced in two human myeloid HL-60 leukemia cell variants by the granulocyte differentiation inducer dimethyl sulfoxide (DMSO) and macrophage differentiation inducer phorbol 12-myristate 13-acetate (PMA). DMSO and PMA also induced the expression and catalytic activity of 2'-5' oligoadenylate synthetase (2-5A synthetase), a known interferon (IFN) inducible enzyme. The HL-60 cell variants included HL-205, which is susceptible to DMSO- and PMA-induced differentiation, and HL-525, which is susceptible to DMSO- but not to PMA-induced differentiation. Treatment of HL-205 and HL-525 cells with DMSO and HL-205 cells with PMA-induced JAK1 phosphorylation, JAK1/STAT1 association, formation of STAT1-STAT2 heterodimers, and the binding of the active IFN stimulating growth factor 3 (ISGF3) to the IFN-stimulated response element (ISRE) fragment isolated from the 2-5A synthetase promoter. These events were either reduced or absent in the resistant HL-525 cells treated with PMA. Taken together, our data implicate the above signaling cascade in DMSO- and PMA-induced 2-5A synthetase expression and catalytic activity in the HL-60 cell system.

Germline mutations in DNA mismatch repair (DNA-MMR) genes, mainly hMlh1 and hMsh2, underlie Hereditary Non-Polyposis Colorectal Cancer (HNPCC). Germline hMSH6 gene mutations have been reported in a small subset of HNPCC families. In the present study, ethnically diverse individuals with HNPCC and HNPCC-like features were genotyped for hMsh6 germline mutations using exon-specific PCR, DGGE, and DNA sequencing. The study encompassed 92 individuals representing 88 unrelated families who were previously analyzed for Msh2 and Mlh1 mutations: Jewish Ashkenazim (n = 44), non-Ashkenazim (n = 27), Israeli Moslem-Arab (n = 15), Druze (n=3), and Cypriot non-Jews (n = 3). Of the study population, 71 had colon cancer (CRC), mean age at diagnosis was 50.9+/-13.2 years (range 16-73 years), 5 had endometrial cancer (two with concurrent CRC), (mean 43.6+/-3.26 years, range 38-45 years), and unaffected individuals (n = 18) were first degree relatives within HNPCC families and were genotyped at a mean age of 48.3+/-11.7 years (range 30-69 years). Of the 92 individuals analyzed, none showed a truncating hMsh6 mutation, and 6 (6.6%) harbored one of three germline missense mutations: a previously reported one (V878A), and two novel mutations (V509A, S227I). The pathogenic significance of these three missense mutations is yet unclear. In addition, 5 polymorphisms were detected, 2 of which were novel. We conclude that the rate of pathogenic hMsh6 mutations in HNPCC families of Jewish and Mediterranean origin is low, and that mutations in other genes probably account for the phenotype in these families.

TPA (12-O-tetradecanoylphorbol-13-acetate), a well-known activator of protein kinase C (PKC), can experimentally induce reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) in certain latently infected cells. We selectively blocked the activity of PKC isoforms by using GF 109203X or rottlerin and demonstrated that this inhibition largely decreased lytic KSHV reactivation by TPA. Translocation of the PKCdelta isoform was evident shortly after TPA stimulation. Overexpression of the dominant-negative PKCdelta mutant supported an essential role for the PKCdelta isoform in virus reactivation, yet overexpression of PKCdelta alone was not sufficient to induce lytic reactivation of KSHV, suggesting that additional signaling molecules participate in this pathway., (Copyright 2004 American Society for Microbiology)

Prostate cancer (PCA) is the leading cause of cancer mortality among older men in Western countries. Epidemiological studies have shown correlation between a lower risk of PCA and a higher consumption of antioxidants. However, the mechanism by which antioxidants exert their effects is still unknown. In the present study, we explored the signaling mechanism through which unique natural antioxidant derived from spinach extract (NAO) exerts their beneficial effects in the chemoprevention of PCA using human PC3 cells. Probing into the effect of NAO and its derived polyphenols on cell-cycle G1 arrest, we found that they cause cell-cycle prolongation. NAO and its two derived purified components exhibited a significant increase in the level of p21cip1 expression after 36 h of starvation, followed by 18 h of treatment with NAO in the presence of serum. In addition, under similar conditions, the expressed level of Cyclin A and CDK-2 in the PC3 cells was significantly reduced after treatment with NAO or its purified components. Immunoblot analysis demonstrated a significant increase in the hypophosphorylated form of pRb and a decrease in ppRb. NAO and its purified derived components were found to downregulate the protein expression of another member of the pRb family, p107, as well as that of E2F-1. These results suggest that NAO-induced G1 delay and cell cycle prolongation are caused by downregulation of the protein expression of ppRb and E2F in the human PCA cell line PC3.

The interferon (IFN)-induced, double stranded RNA (dsRNA)-activated serine/threonine kinase, PKR, is a potent negative regulator of cell growth when overexpressed in yeast or mammalian cells. Paradoxically, while it can function as a tumor suppressor and inducer of apoptosis, it is overexpressed in a variety of human cancers. To resolve this enigma, we established cell-lines that overexpress PKR in non-transformed and in v-mos transformed CHO cells. Overexpression of PKR suppressed the proliferation of CHO cells by inducing a transient G0/G1 arrest, followed by a delayed G2/M arrest, which attenuated cell cycle progression. These effects were accompanied by early induction of p21/WAF-1 and delayed downregulation of CDC2 and cyclin B1. Induction of proapoptotic activity of the ectopic PKR paralleled the onset of G2/M arrest in CHO cells. However, while transiently inducing p21/WAF-1, PKR did not impose G2/M arrest or apoptosis in v-mos-transformed cells, nor was CDC2 or cyclin B1 down-regulated in those cells. These findings link the proapoptotic activity of PKR to the arrest of cell cycle at the G2/M phase. Consequently, the apoptotic activity of PKR could be counter-acted by an oncogene-like v-mos that overrides the G2/M arrest induced by PKR.

In this report we review the current knowledge on the involvement of the interferon (IFN) system in the regulation of cell growth and differentiation. We also summarize our own data which provide evidence for the strong correlation between IFN-mediated growth-arrest of transformed cells and the elevated enzymatic activity of an IFN-induced protein. Similarly, it is demonstrated that elevated levels of IFN-induced proteins accompany the early phases of in-vitro cell differentiation. IFN-treatment of NIH/3T3 mouse fibroblasts transformed by Moloney-murine sarcoma virus (MSV) resulted in a significant reduction in the rates of cell growth, protein synthesis and cloning efficiency. In parallel, 2-5A-synthetase activity was induced ten-fold above the background level. Treatment of these cells for 3 days with 450 international units (IU)/ml of IFN followed by its removal, resulted in a gradual increase in all parameters associated with cell growth while the 2-5A-synthetase activity was reduced to its normal level. However, almost no recovery occurred when cells were treated with 1,800 IU/ml. In parallel, 2-5A-synthetase activity remained highly elevated even at 3 days after the removal of IFN. In these cells, the expression of both c-myc and v-mos was reduced rapidly following IFN treatment. Upon removal of IFN after 24 h of treatment, the expression of both genes was resumed but with a different kinetics, suggesting that different mechanisms are responsible for the reduction in gene expression. In rat skeletal muscle cultures which differentiate to form myotubes, the level of both 2-5A-synthetase and protein kinase activities was transiently elevated, reaching a peak at 3 days followed by a decrease to background levels. This peak activity precedes the appearance of the major muscle differentiating proteins.