A potential role of nuclear matrix-associated protein kinase CK2 in protection against drug-induced apoptosis in cancer cells

Protein kinase CK2 (CK2) has long been implicated in the regulation of cell growth and proliferation. Its activity is generally elevated in rapidly proliferating tissues, and nuclear matrix (NM) is an important subnuclear locale of its functional signaling. In the prostate, nuclear CK2 is rapidly lost commensurate with induction of receptor-mediated apoptosis after growth stimulus withdrawal. By contrast, chemical-induced apoptosis in prostate cancer and other cells (by etoposide and diethylstilbestrol) evokes an enhancement in CK2 associated with the NM that appears to be because of translocation of CK2 from the cytoplasmic to the nuclear compartment. This shuttling of CK2 to the NM may reflect a protective response to chemical-mediated apoptosis. Supporting evidence for this was obtained by employing cells that were transiently transfected with various expression plasmids of CK2 (thereby expressing additional CK2) prior to treatment with etoposide or diethylstilbestrol. Cells transfected with the CK2alpha or CK2alphabeta showed significant resistance to chemical-mediated apoptosis commensurate with the corresponding elevation in CK2 in the NM. Transfection with CK2beta did not demonstrate this effect. These results suggest, for the first time, that besides the commonly appreciated function of CK2 in cell growth, it may also have a role in protecting cells against apoptosis.

The prevalence and clonal diversity of penicillin-resistant Streptococcus pneumoniae in Kuwait

Penicillin-resistant Streptococcus pneumoniae (PRSP) is widespread all over the world, including countries previously free of PRSP. This study was undertaken to determine the prevalence, the common serotypes and the clonality of PRSP isolated over a period of 1 year, from various clinical samples from three major hospitals in Kuwait. Strains were identified by standard methods and their antibiotic susceptibility was determined by the agar dilution method. The clonality of the isolates was determined by repetitive extragenic palindromic sequence polymerase chain reaction (REP-PCR) genomic profiling and pulsed field gel electrophoresis (PFGE). Serotyping was done by Quellung reaction using specific antisera. We found that 55% of the S. pnuemoniae were resistant to penicillin (46% and 9% exhibited intermediate and full resistance, respectively). Nearly 41% were resistant to sulfamethoxazole-trimethoprim, 9% to cefotaxime and ceftriaxone, 15% to amoxycillin-clavulanate, 17% to cefuroxime, 77 % to cefaclor, and 14% to clindamycin. The commonest serotypes among the PRSPs were 6A, 6B, 14, 19F, 23F and nontypable. PFGE and REP-PCR patterns showed a large diversity of genetic clones of the PRSP. Serotypes 6B, 14, 19F and 23F were more clonally related than the others. Our data showed that the prevalence of PRSP was high, the serotypes were diversified and different genetic clones make up the population of circulating PRSP in Kuwait.

Efficacy of concomitant chemoradiation and surgical salvage for N3 nodal disease associated with upper aerodigestive tract carcinoma

OBJECTIVES/HYPOTHESIS

To determine whether an aggressive approach using trimodality therapy would improve the outcome in head and neck cancer patients with advanced (N3) nodal disease.

STUDY DESIGN

In this retrospective, nonrandomized review, we analyzed a subset of patients who were treated in a targeted chemoradiation therapy protocol, consisting of 31 patients who received treatment between June 1993 and June 1997.

METHODS

Patients received selective intra-arterial infusions of cisplatin (150 mg/m2/wk for 4 weeks) and concomitant radiation therapy (2 Gy/fraction x 35 daily fractions over a 7-wk period) to the primary and clinically positive nodal disease. The patients were re-evaluated 2 months later and underwent salvage neck dissections if there was any residual disease.

RESULTS

Classification of disease in the primary site was as follows: T1 in 2 patients, T2 in 6 patients, T3 in 14 patients, and T4 in 9 patients. Among the 31 patients who were assessed for response at the nodal site, 4 of 31 (13%) had a complete response, 21 of 31 (68%) had a partial response, and 1 of 31 (3%) had no response. Excluding the 5 patients who could not be evaluated, 4 of 26 patients (15%) had a complete response, 21 of 26 (81%) had a partial response, and 1 of 26 (4%) had no response. Nineteen patients subsequently underwent neck dissection, and five patients had histological evidence of residual disease. The remaining seven patients included four who had a complete response in their necks and three who died of intercurrent disease before re-staging. Among the 23 patients who were rendered disease free, there were no recurrences within the neck, whereas 1 patient had recurrence at the primary site and 11 patients had recurrence at distant sites. With a median follow-up of 15 months (range, 4-41 mo), the 3-year overall survival and disease-specific survival were 41% and 43%, respectively.

CONCLUSIONS

Targeted chemoradiation therapy followed by surgical salvage is a highly effective approach for regional control of patients with N3 nodal disease, whereas additional strategies are required to address the problem of distant metastases.

Cutaneous hyalohyphomycosis caused by Paecilomyces lilacinus in a renal transplant patient

We describe a renal transplant recipient with cutaneous hyalohyphomycosis due to Paecilomyces lilacinus and highlight the increasing importance of such opportunistic fungal infections in immunosuppressed patients.

Death and dying abroad: the Canadian experience

BACKGROUND

The objective was to examine the characteristics of international travelers from Canada, who have died while abroad, and to review the health protection and promotion strategies for prevention of adverse health outcomes associated with travel, which may have prevented these deaths.

METHOD

An EpiInfo 6 program was created to analyse all of the Consular reports received in 1995 via the Secure Integrated Global Network, which provides communications and computerization services to the Department of Foreign Affairs and International Trade, Canada. The Consular Management and Operations System was designed to support the delivery of consular services by the Department, and to link Headquarters in Ottawa with missions in other countries, through case management files, including a "Death Abroad" file. The type of data collected included personal demographics (age, gender), date, country, and cause of death.

RESULTS

In 1995, consular services received 309 reports of Canadians dying abroad. Two hundred and twenty deaths were males (71.2%), and 69 were females (22.3%). The average age (56 years) and median age (43 years) were similar for males and females (age range 0.3-86 years). Recorded causes of death were: natural (62.1%), accidents (24.9%), murder (7.8%), and suicide (5.2%). Cardiovascular disease and trauma were the two most commonly specified causes of death.

CONCLUSIONS

At least 36% of the deaths occurring in Canadian travelers would be considered preventable. Pretravel medical interventions for travelers with known preexisting medical problems, may have prevented many more deaths. International travelers need to be aware of the health risks associated with travel. Access to appropriate health risk assessment, prior to exposure, in many cases, would have prevented death abroad.

Antisense oligonucleotides against protein kinase CK2-alpha inhibit growth of squamous cell carcinoma of the head and neck in vitro

BACKGROUND

Human squamous cell carcinomas of the head and neck (SCCHN) overexpress the protein kinase CK2, and elevated CK2 activity correlates with aggressive tumor behavior and poor clinical outcome. We therefore investigated whether interference with CK2 expression would inhibit SCCHN cell growth in vitro.

METHODS

We targeted the catalytic (alpha) subunit of CK2 using an antisense oligodeoxynucleotide (ODN) strategy. Human Ca9-22 cells derived from SCCHN were transfected with CK2-alpha sense, nonsense, or antisense ODN; CK2 activity was measured; and the effect on CK2 activity and on cell growth was determined.

RESULTS

Transfection of Ca9-22 cells with antisense CK2-alpha ODN resulted in significantly decreased CK2 kinase activity associated with nuclear chromatin and in dose-dependent growth inhibition of Ca9-22 cells in vitro.

CONCLUSIONS

Interference with the protein kinase CK2 signal in SCCHN cells may offer a novel anticancer strategy for this malignancy.

Jejunal obstruction and perforation resulting from herniation through broad ligament

Internal herniation of small bowel through broad ligament causing obstruction is rare. A case of jejunal herniation through broad ligament defect with resultant obstruction and perforation is presented.

Arrest and detention in international travelers

BACKGROUND

Our objective was to examine the characteristics of international travelers from Canada who have been arrested or detained while abroad, and to review the health implications of incarceration.

METHOD

An EpiInfo 6 program was created to analyse all of the Consular reports received in 1995 via the Secure Integrated Global Network (SIGNET) which provides communications and computerization services to the Department of Foreign Affairs and International Trade, Canada. The Consular Management and Operations System was designed to support the delivery of consular services by the Department, and to link Headquarters in Ottawa with missions in other countries through case management files, including a "Prisoners" file. Information obtained included personal demographics (age, gender), date, country, and reason for arrest or detention, and outcome of judicial process.

RESULTS

There were 1, 086 arrest or detention reports received from Consular services via SIGNET in 1995. Males outnumbered females 5.6:1. Most individuals arrested were young: 57.5% were less than 40 years, and 79% were less than 50 years. Drug related charges were cited in 33.1% of all cases, with 52.8% of arrested females charged with drug related offenses. The documented conviction rate was 96%. The majority of detained Canadian travelers were held in countries within the Americas (791 cases - 69.2%), with 642 (59.1%) being detained in the USA.

CONCLUSIONS

Arrest and detention is an unusual occurrence for international travelers but relative youth, male gender, and female drug couriers were identifiable risk characteristics. Public awareness campaigns can be targeted to specific population demographics, but all international travelers need to be counseled on the consequences of transgressing laws in foreign countries.

Attachment of Moraxella catarrhalis occurs to the positively charged domains of pharyngeal epithelial cells

Attachment of bacteria to host cells is the initial step in the pathogenesis of infection. Several factors, such as hydrophobicity, surface electric charge, and van der Waals force, are considered to be responsible for the attachment step. However, it is not clear why bacteria and epithelial cells, both of which possess a negative surface charge, do not repel one another. In the present study, we used Moraxella catarrhalis and pharyngeal epithelial cells to study the surface charges of structures involved in the attachment. By atomic force microscopy (AFM) equipped with surface potential spectroscopy, it was found that the cell surface microplicae have a positive charge of 30.1+/-3.6 mV (mean+/-SE). The depressions between the microplicae have a negative surface charge of 43.5+/-4.0 mV. Using cationic ferritin and electron microscopy (EM) we confirmed that the depressions between the microplicae have a negative charge. By AFM and by using cationic ferritin with EM, it was found that the net surface charge of the bacterial cells is negative. By both AFM and EM, it was found that the bacterial cells attach to the microplicae of the pharyngeal epithelial cell. Our work confirmed the general belief that both kinds of cells do have a net negative charge. We conclude that there are positively and negatively charged domains on the surface of human pharyngeal epithelial cells. M. catarrhalis evidently attaches to the positively charged domain (i.e. microplicae) of pharyngeal epithelial cells.

Response of Osteosarcoma to Chemotherapy. Evaluation with F-18 FDG-PET Scans

Objective: Positron emission tomography (PET) using fluorine-18-fluoro-2-D-deoxyglucose (FDG) is increasingly being used to evaluate and manage oncology patients. Several reports have documented its utility in diagnosis, staging, response to treatment, and tumor viability assessment. There is, however, a paucity of literature on PET scanning in patients with osteosarcoma. We report results of serial F-18 FDG-PET scans in 16 untreated patients with osteosarcoma who underwent chemotherapy prior to surgical resection of the primary tumor site.Procedure: Changes in tumor fluoro-2-D-deoxyglucose (FDG) uptake were correlated with percent tumor necrosis on histopathology. PET studies were analyzed by visual assessment of tumor uptake of FDG by 3 independent observers, calculating a tumor to normal background activity ratio (TBR) by drawing regions of interest (ROIs) around the tumor and background activity in the contralateral normal limb, and percent change in TBR values between baseline and presurgical study.Results: All patients had positive baseline scans. Baseline TBRs ranged between 2.5-8.7 and visual assessment of intensity of FDG uptake was 2-3 on a scale of 0-3. At histopathologic examination, 8 patients were classified as good responses with more than 90% tumor necrosis and 8 patients as poor responses with less than 90% necrosis. Tumor necrosis was accurately predicted on PET scan in 15/16 patients by visual assessment, 14/15 patients by final TBR value on presurgery scans, and 7/15 patients using percent change of TBR on serial scans.Conclusions: The results of this small series suggest that FDG-PET scanning is fairly accurate in evaluating the response of osteosarcoma to chemotherapy. Visual assessment and TBR are more accurate in predicting tumor necrosis than percent change in TBR on serial scans.

Nuclear matrix and protein kinase CK2 signaling

The dynamic functional nature of the nuclear matrix dictates that it provide a locus for molecules involved in nuclear transduction of signals, such as those participating in cell growth control. Protein kinases are key elements in a variety of signaling mechanisms and certain of these enzymes have been shown to associate with the NM. Among these, the protein ser/thr kinase CK2 has attracted considerable attention because of its involvement in cell growth. NM appears to be a preferential locus for CK2, as evidenced from its rapid modulation in the NM in response to hormonal and growth factor signals. Differential regulation of CK2 is also noted in the transcriptionally active and inactive nucleosomes. A number of potential substrates for CK2 are localized to the NM. Likewise, distinct substrates for CK2 are noted in the transcriptionally active compared with inactive nucleosomes. The dynamics of phosphorylation of these substrates and that of the association of CK2 activity to these fractions suggests that CK2 may play a role in the functional activities of NM and provide a link between the NM and nucleosomes by serving as a factor in promoting the transition of inactive to active nucleosome.

Influence of five antianaerobic antibiotics on endotoxin liberation by gram-negative anaerobes

Endotoxin, a lipopolysaccharide (LPS), has for many years been recognized as a key effector molecule in the pathogenesis of gram-negative sepsis and septic shock. Seven strains of the Bacteroides fragilis group were studied for their ability to liberate endotoxin upon exposure to five anti-anaerobic antibiotics, trovafloxacin, cefoxitin, imipenem, meropenem and piperacillin/tazobactam, in an in-vitro experiment. The minimum inhibitory concentrations (MICs) of the antibiotics were determined by using the broth macrodilution technique. Thereafter, endotoxin liberation was detected in the filtered broth cultures of the anaerobic bacteria by the limulus amebocyte lysate (LAL) assay after exposing the organisms to four different concentrations of the antibiotics in supplemented Brucella broth. Aliquots of the broth cultures were also taken at intervals of 0, 6, 24 and 48 h for viable counts. All seven gram-negative anaerobic bacteria investigated liberated induced cell-free endotoxin in filtered broth culture many times higher than the control. There was noticeable variation in the propensity of some antibiotics to induce endotoxin liberation. At four times the MICs, cefoxitin and piperacillin/tazobactam induced negligible quantities of endotoxin after 48 h exposure, whereas the others induced high levels of endotoxin release. After exposure to all concentrations for 48 h, endotoxin activity in the test system was many times higher with the Bacteroides fragilis sensu stricto than with the rest of the species in the Bacteroides group. To varying degrees, all five antibiotics had the capacity to induce endotoxin liberation by gram-negative anaerobic bacteria. This differential endotoxin release by the B. fragilis group may, in part, explain why B. fragilis sensu stricto, more than the other Bacteroides spp., is usually associated with clinical infections and higher morbidity.

Causative bacteria of respiratory tract infections in Kuwait by quantitative culture of sputum

To determine the bacterial etiology of lower respiratory tract infections in Kuwait, we performed quantitative culture of sputum and measured the susceptibilities of the isolated bacteria against different antibiotics. A total of 140 sputum samples were collected for a period of 14 months for the study. Single and multiple pathogens as a cause of infection were isolated from 55 and 15 samples, respectively. A total of 53.8% of Streptococcus pneumoniae were penicillin-resistant and 52% and 57% of Hemophilus influenzae and Moraxella catarrhalis were beta-lactamase positive, respectively. We concluded that the major pathogens of respiratory tract infections in Kuwait were H. influenzae, M. catarrhalis, S. pneumoniae, and Pseudomonas aeruginosa, and there was an increased resistance among the isolated bacteria against commonly used antibiotics.

Lung cancer: occurrence and new possibilities for detection

Lung cancer is the leading cause of death worldwide. Physical and chemical agents such as tobacco smoke are the leading cause of various lung cancers. The intrinsic heterogeneity of normal lung tissue may be affected in different ways, giving rise to different types of lung cancers classified as either small‐cell lung cancer (SCLC) or non‐small cell lung cancer (NSCLC). Adenocarcinoma, a NSCLC, accounts for 40 percent of all lung cancer cases and the incidence is increasing worldwide, especially among women. The survival rate and prognosis is poorest for adenocarcinoma. Therefore, diagnosis at the earliest stage (Stage I, localized) is critical for increasing survival rates of those suffering from lung cancer. However, many factors affect early diagnosis including the variable natural growth of tumors plus technological and human factors associated with manipulation of tissue samples and interpretation of results. This article reviews potential problems associated with diagnosing lung cancer and considers future directions of diagnostic technology.

Subcellular immunolocalization of protein kinase CK2 in normal and carcinoma cells

CK2 is a messenger-independent protein serine/threonine kinase that has been implicated in cell growth and proliferation. Our recent analysis of squamous cell carcinomas of the head and neck (SCCHN) revealed a significant elevation in CK2 activity in these tumor cells relative to normal mucosa of the upper aerodigestive tract and suggested a correlation with aggressive tumor behavior and poor clinical outcome. In order to further define the distribution of CK2 in these tissues, we have examined the immunohistochemical staining pattern of surgical specimens of both SCCHN tumors and normal upper aerodigestive tract mucosa using a monoclonal antibody directed against the catalytic subunit CK2-alpha of the kinase, and have compared these data with the subcellular distribution of CK2 activity in these same tissues. These measurements showed that CK2 is predominantly localized to the nuclei of the tumor cells, which agreed closely with the immunohistochemical staining pattern of CK2-alpha in tumor cells. The chiefly nuclear distribution of CK2-alpha immunostaining found consistently in SCCHN tumor cells and tumor-infiltrating lymphocytes contrasted with a relatively more predominant cytosolic staining pattern exhibited by various cellular constituents of normal oropharyngeal mucosa. The immunostaining pattern of CK2-alpha revealed that staining was observed in the cells stained for the proliferation-marker Ki-67; however, strong distinct immunostaining for CK2-alpha was also observed in large numbers of other cells in these same tumors, suggesting that CK2 elevation in these tumors is not a reflection of proliferative activity alone, but may also relate to the pathobiological behavior of the tumor.

Mediation of attachment of Burkholderia pseudomallei to human pharyngeal epithelial cells by the asialoganglioside GM1-GM2 receptor complex

Melioidosis is the term given to any infection caused by Burkholderia pseudomallei. This bacteria is one of the important causative agents of life-threatening pulmonary infections in the tropical and subtropical areas. The initiation of respiratory infections is attachment of this bacteria to pharyngeal cells. The precise mechanism of attachment of B. pseudomallei is not known. In this study, we found that asialoganglioside GM1 at concentrations of 25, 12.5, and 5 microg/ml significantly decreased the attachment of B. pseudomallei strain Sp-186 in a dose-dependent manner. On the other hand, asialoganglioside GM2 decreased the attachment of B. pseudomallei, but only at a concentration of 25 microg/ml. At a concentration of 1 mg/ml, glucose, N-acetyl-galactosamine, and galactose caused a significant decrease in attachment. However, at concentrations of 250 microg/ml, no decrease in attachment was observed in B. pseudomallei treated with these carbohydrates. Mannose and fucose at concentrations of 1 mg/ml had no effects on the inhibition of attachment of B. pseudomallei. Four other isolates of B. pseudomallei showed a significant decrease in attachment after treatment with asialoganglioside GM1. We conclude that asialogangliosides GM1 and GM2 are part of the receptor complex for B. pseudomallei on human pharyngeal epithelial cells.

Increased serum levels of interferon-gamma and interleukin-12 during human brucellosis

Brucellosis is a zoonotic disease that often becomes chronic with a high rate of recurrence. To understand the cytokines induced during this infection we determined the levels of interleukin (IL)-1beta, IL-2, IL-4, IL-8, IL-12, tumor necrosis factor-of (TNF-alpha) and interferon-gamma (IFN-gamma) in serum of patients with brucellosis and compared with those without brucellosis and controls. Control sera were taken from healthy persons residing in an area that was not endemic for brucellosis. The levels of IL-1, IL-2, IL-4, and TNF-alpha were not detectable in all the sera from patients. There was no difference in the level of IL-8 in patients with brucellosis and those without this disease. However, IL-8 was significantly higher in these two groups of patients compared with the controls. Significantly higher levels of IL-12 and IFN-alpha were found in the serum of patients with brucellosis compared with patients without brucellosis and controls. These data indicate that there is induction of Thl type cytokines during human brucellosis.

Differential targeting of protein kinase CK2 to the nuclear matrix upon transient overexpression of its subunits

Modest dysregulation of CK2 has been shown to enhance the oncogenic potential in transgenic models of cancer. Since nuclear matrix serves as an anchor for CK2 and plays a key role in growth-related activities, we examined the effects of CK2 overexpression on its signaling to the nuclear matrix. Expression plasmids pCI-CK2alpha, pCI-CK2beta, and the bicistronic pCI-CK2alphabeta containing full length cDNAs encoding the various subunits were employed to transiently transfect two cell lines, BPH-1 and COS-1. Cytosol from transfected BPH-1 cells containing alpha or beta or alpha + beta or alphabeta showed a modest increase in CK2 activity by 26%, 1%, 20%, and 17%, respectively, over that in the controls transfected with pCI vector. However, the corresponding increase in CK2 activity in the NM fraction was 156%, 8%, 147%, and 152%, respectively. Immunoblot analysis of the CK2 in the NM accorded with these data. Similar results were obtained with COS-1 cells or other expression vectors. The results suggest that moderate overexpression of CK2 in the cells evokes a differential several-fold enhancement in NM associated CK2 relative to that in the cytosol. This process may have a bearing on the functional signaling of this kinase in relation to its possible role in oncogenesis.

DNA restriction patterns produced by pulsed-field gel electrophoresis in Moraxella catarrhalis isolated from different geographical areas

Pulsed field gel electrophoresis (PFGE) of the genomic DNA of Moraxella catarrhalis was done in 172 strains isolated from sputum of patients with respiratory infections in Nagasaki (130 strains), Europe (14 strains), Thailand (6 strains), Uganda (3 strains), Bangladesh (5 strains) and Kuwait (14 strains). Restriction endonuclease with SmaI generated 4-16 DNA fragments ranging from 1000 kb to 24.25 kb and was classified into 31 major groups. It was found that there were wide variations of DNA restriction patterns of strains isolated from the same and different geographical areas. DNA restriction patterns of strains isolated in Nagasaki during the last 12 years showed dynamic changes of the predominant strains in each time period. We conclude from this study that PFGE is a suitable method to document interstrain variation in M. catarrhalis.

Biodistribution studies of the 186Re complex of 3-amino-1-hydroxypropylidene-1,1-bisphosphonic acid in mice

Preliminary studies of 186Re-labelled 3-amino-1-hydroxypropylidene-1, 1-bisphosphonic acid (APD) were performed to determine its potential for bone pain palliation, and as a treatment for increased bone resorption. The synthesis of 186Re-APD was carried out by reduction of 186Re-perrhenate in the presence of SnCl2. The APD kit, comprising 2.5 mg of APD, 2.5 mg of gentisic acid and 1 mg of Sn++ as SnCl2 2H2O, was prepared in-house. The APD was labelled with 186Re and injected intravenously into normal mice. Mice were subsequently sacrificed at 1, 3, 24, 48, 72, 168 and 240 h post-injection. The greatest accumulation of 186Re-labelled APD was found in bone, resulting in bone-to-blood ratios of 25, 35, 65, 100, 151, 181 and 189, respectively. 186Re-APD showed high uptake in bone, and relatively low uptake in soft tissue, suggesting that 186Re-APD is a potential agent for bone therapy.

The effects of S-carboxymethylcysteine and N-acetylcysteine on the adherence of Moraxella catarrhalis to human pharyngeal epithelial cells

We investigated the effects of two mucoregulating drugs, S-carboxymethylcysteine (S-CMC) and N-acetylcysteine (NAC), on the attachment of Moraxella catarrhalis (M. catarrhalis) to pharyngeal epithelial cells. The attachment of M. catarrhalis decreased (33-57%) significantly (P<0.01) in a dose-dependent manner in cells treated with mucoregulating drugs as compared to the control. There was a significant (P<0.01) decrease (35-45%) in the attachment of M. catarrhalis to pharyngeal cells after oral administration of S-CMC. By electron microscopic observation, it was found that there was a fine, granular, electron-dense, ruthenium red-positive layer on the surface of pharyngeal epithelial cells; this layer was absent on cell surfaces treated with mucoregulating drugs. Possibly, this layer contained the portion of M. catarrhalis receptor which is responsible for the attachment of this bacteria to pharyngeal epithelial cells. From the above results, it may be concluded that one of the mechanisms of mucoregulating drugs to decrease the episode of respiratory infections in patients with chronic respiratory diseases is by inhibiting the attachment of bacteria to the upper respiratory tract.

Apoptosis and growth inhibition of head and neck tumor cell line induced by epidermal growth factor receptor tyrosine kinase inhibitor

Overexpression of the epidermal growth factor (EGF) receptor, a hallmark of aerodigestive squamous cell carcinoma of the head and neck (SCCHN), correlates with aggressive tumor behavior. There is evidence that SCCHN cells auto-activate their EGF receptors. The receptor has therefore attracted interest as a potential therapeutic target. We tested the in vitro therapeutic efficacy of PD153035--a potent, specific inhibitor of the tyrosine kinase intrinsic to the EGF receptor--by employing a well-characterized cell line derived from human gingival SCCHN. DNA-synthesis and cell number were assayed for growth-inhibitory effects, phosphorylation of the EGF receptor was quantitated by immunoblot, and cell apoptosis was detected by terminal deoxytransferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling (TUNEL) in situ assay. PD153035, at nanomolar concentrations, inhibited autophosphorylation of the EGF receptor induced by EGF stimulation and the inhibition occurred in a dose-dependent manner. Under the same conditions, PD153035 inhibited cell growth, and induced apoptosis of SCCHN cells in vitro. We conclude that selective inhibition of the EGF receptor tyrosine kinase completely abolishes EGF receptor phosphorylation resulting from receptor stimulation, and results in growth inhibition and apoptosis of SCCHN cells in vitro. By inducing cytostasis and apoptosis, this new class of inhibitors may be of therapeutic value against SCCHN.

Nuclear matrix targeting of the protein kinase CK2 signal as a common downstream response to androgen or growth factor stimulation of prostate cancer cells

Protein kinase CK2, a messenger-independent serine/threonine kinase, has been implicated in cell growth. Androgenic stimulus in rat prostate modulates its association with nuclear matrix (NM) and chromatin. Because the growth of human prostate carcinoma cells is influenced by androgens and/or growth factors, we determined the nature of CK2 signaling in the NM in response to androgen and growth factor stimuli. Androgen-sensitive LNCaP and androgen-insensitive PC-3 cells were cultured in media to regulate their growth in the presence of 5alpha-dihydrotestosterone (5alpha-DHT) or growth factors (epidermal growth factor, keratinocyte growth factor, and transforming growth factor alpha). The activity of CK2 was measured in the cytosolic and NM fractions isolated from these cells after treatment with growth stimuli. The changes in CK2 in various fractions were also confirmed by immunoblotting with a specific antibody. LNCaP cells responded to both 5alpha-DHT and growth factors for growth. The presence of these agents in the culture medium evoked a translocation of CK2 to the NM from the cytosol. The PC-3 cells did not respond to 5alpha-DHT for growth but did respond to growth factors. Under these conditions, there was also a translocation of CK2 to the NM concomitant with a decrease in the cytosolic fraction. These results suggest that CK2 translocation to the NM occurs in response to various growth stimuli in cells in culture. Thus, CK2 is a common downstream signal transducer in response to diverse growth stimuli that may relate to the pathobiology of prostate cancer cells.