Expression of dominant negative Erk2 inhibits AP-1 transactivation and neoplastic transformation

The mitogen activated protein (MAP) kinases or extracellular signal-regulated kinases (Erks) are activated in response to Ras expression or exposure to tumor promoters or to growth factors, and have been implicated in AP-1 transactivation in some models. We have shown that tumor promoter induced activation of the transcription factor AP-1 is required for induced neoplastic transformation in the Balb/C JB6 cell model. Jun and Fos family protein levels have been found not to be limiting for AP-1 response. The present study asks whether activation of Erks1 and 2 is required for AP-1 transactivation and transformation of JB6 cells and whether Erks might be targeted for cancer prevention. Expression of either of two different dominant negative kinase inactive Erk2 mutants in transformation sensitive (P+) JB6 cells substantially inhibited the tumor promoter induced activation of Erks1 and 2 and of AP-1 measured by a collagenase-luciferase reporter. Multiple mutant Erk2 expressing clonal lines were also rendered non-responsive to induced neoplastic transformation. These observations, together with our recent finding attributing AP-1 non-responsiveness to Erk deficiency in a clonal line of transformation resistant (P-) cells, argue for a requirement for Erks1 and/or 2 activation in AP-1 transactivation in the mouse JB6 neoplastic progression model, and suggest the utility of Erks as a prevention target.

Antisense ablation of type I metabotropic glutamate receptor mGluR1 inhibits spinal nociceptive transmission

Electrophysiological and behavioral studies point to a role of group I metabotropic glutamate receptors (mGluR1 and mGluR5) in mediating spinal nociceptive responses in rats. However, antagonists with a high degree of specificity for each of these sites are not yet available. We, therefore, examined the effects of antisense deletion of spinal mGluR1 expression in assays of behavioral analgesia and of electrophysiological responses of dorsal horn neurons. Rats treated with an mGluR1 antisense oligonucleotide reagent, delivered continuously to the intrathecal space of the lumbar spinal cord, developed marked analgesia as measured by an increase in the latency to tail-flick (55 degreesC) over a period of 4-7 d. This correlated with a selective reduction in mGluR1, but not mGluR5, immunoreactivity in the superficial dorsal horn compared with untreated control rats, in parallel with a significant reduction in the proportion of neurons activated by the mGluR group I agonist 3, 5-dihydroxyphenylglycine (DHPG), whereas the proportion of cells excited by the mGluR5 agonist, trans-azetidine-2,4-dicarboxylic acid (t-ADA) remained unaffected. In contrast, rats treated with mGluR1 sense or mismatch probes showed none of these changes compared with untreated, control rats. Furthermore, multireceptive dorsal horn neurons in mGluR1 antisense-treated rats were strongly excited by innocuous stimuli to their peripheral receptive fields, but showed severe reductions in their sustained excitatory responses to the selective C-fiber activator mustard oil and in responses to DHPG.

Thermoprotective mechanisms of irrigation during bipolar cautery

Bipolar cautery is routinely used in operations of the head and neck, as well as in other specialties, both for dissection and for achieving hemostasis. Whereas simultaneous irrigation is frequently used to minimize neuronal injury, its effectiveness has not been tested under controlled conditions. Our objectives in this study were to test the hypothesis that including irrigation during bipolar cautery is thermoprotective and to identify the mechanisms underlying the thermoprotective effect. The thermoprotective role of irrigation with bipolar cautery was tested in a rat model in which the sciatic nerve was exposed and a 1-second stimulus at 40 or 20 watts was applied with bipolar cautery forceps placed directly on the nerve in the presence or absence of simultaneous irrigation. We used the Sciatic Functional Index as used to quantitate the degree of paresis induced. The results showed that simultaneous irrigation reduced the percentage of animals showing paresis. This effect was significant for animals exposed to 40- and 20-watt cautery. The mechanism for the reduction in the degree of paresis by irrigation could not be attributed to a lowering of the maximal temperature achieved after bipolar cautery. Instead, the thermoprotective mechanism of the irrigation involved an enhanced recovery to basal temperatures when measured at 15 seconds after nerve stimulation with 40 or 20 watts. Reducing the power from 40 watts to 20 watts did not significantly lessen the tissue temperature. The results of this study suggest that irrigation done simultaneously with bipolar cautery enhances temperature recovery to basal levels and plays a role in thermoprotection against the effects of cautery.

Once-weekly fluconazole (450 mg) for 4, 6, or 9 months of treatment for distal subungual onychomycosis of the toenail

BACKGROUND

Fluconazole is a bis-triazole antifungal agent approved for the treatment of oropharyngeal, esophageal, and vaginal candidiasis, serious systemic candidal infections, and cryptococcal meningitis.

OBJECTIVE

The purpose of this study was to evaluate three different durations of once-weekly fluconazole for the treatment of onychomycosis of the toenail caused by dermatophytes.

METHODS

In a multicenter, randomized, double-blind, parallel, placebo-controlled trial, 384 patients with distal subungual onychomycosis of the toenail received fluconazole, 450 mg once weekly, or placebo for 4, 6, or 9 months. For inclusion, patients were required to have mycologically confirmed distal subungual onychomycosis of the toenail with a large toenail at least 25% clinically affected but having at least 2 mm of healthy nail between the nail fold and the proximal onychomycotic border. Efficacy was assessed by clinical and mycologic (microscopic and microbiologic) measures at screening, at every treatment visit starting at month 3, and at months 2, 4, and 6 after therapy. Observed or volunteered adverse events were recorded and classified at all visits.

RESULTS

At the end of treatment, very significantly superior clinical and mycologic results were achieved in all fluconazole groups compared with placebo (p=0.0001). This superiority was largely maintained over 6 months of follow-up. The clinical and mycologic responses of the 9-month treatment duration were significantly superior to the 4- and 6-month durations. Similar percentages of patients in the fluconazole and placebo groups reported adverse experiences for all three durations of the study.

CONCLUSION

Results of this study support the efficacy and safety of fluconazole in the treatment of distal subungual onychomycosis of the toenail.

Failure of tumor-reactive lymph node cells to kill tumor in the presence of immune-suppressive CD34+ cells can be overcome with vitamin D3 treatment to diminish CD34+ cell levels

Growth of Lewis lung carcinoma (LLC-LN7) tumors results in an increase in CD34+ granulocyte-macrophage progenitor cells having natural suppressor (NS) activity. These CD34+ NS cells were capable of inhibiting the cytotoxic activity of tumor-reactive lymph node cells. In vivo studies showed that adoptive treatment of LLC-LN7 tumor-bearing mice with tumor-reactive lymph node cells plus IL-2 failed to reduce the development of metastases. Studies were conducted to determine if diminishing the levels of CD34+ NS cells would allow for improved anti-tumor effectiveness of the adoptively transferred cells. The suppressive activity of CD34+ cells toward the cytolytic activity of tumor-reactive lymph node cells could be blocked by in vitro culture of CD34+ cells with the differentiation-inducing hormone 1alpha,25-dihydroxyvitamin D3. Similarly, treatment of LLC-LN7-bearing mice with vitamin D3 alone diminished the levels of CD34+ NS cells within regional lymph nodes, spleens and tumors. This treatment resulted in an increased immune reactivity to autologous tumor, as shown by the production of IFN-gamma by lymph node cells in response to the presence of LLC-LN7 cells. The extent of tumor metastasis in mice receiving vitamin D3 treatment was also reduced. When tumor-reactive lymph node cells were adoptively transferred into these LLC-LN7-bearing mice that were receiving vitamin D3 treatment, there resulted a pronounced synergistic reduction in tumor metastasis. The results of this study show that treatment of tumor bearers with vitamin D3 to eliminate CD34+ NS cells improves the anti-tumor effectiveness of adoptively transferred tumor-reactive lymph node cells.

Shortage of mitogen-activated protein kinase is responsible for resistance to AP-1 transactivation and transformation in mouse JB6 cells

The JB6 mouse epidermal cell system, which includes tumor promotion-sensitive (P+) and tumor promotion-resistant (P-) cells, is a well-established and extensively used cell culture model for studying the mechanism of late-stage tumor promotion. Tumor promoters, such as 12-O-tetradecanoylphorbol 13-acetate (TPA) or epidermal growth factor (EGF), induce high levels of activator protein 1 (AP-1) activity and large, tumorigenic, anchorage-independent colonies in soft agar at a high frequency in JB6 P+ cells, but not in JB6 P- cells. We report here a molecular explanation for the defect in the AP-1 activation and promotion-resistant phenotype of P- cells. We demonstrate that the lack of AP-1 activation and cell transformation responses to TPA and EGF in P- cells appears attributable to the low level of mitogen-activated protein kinase (MAPK) (extracellular signal-regulated protein kinase, Erk) in these cells. TPA and EGF induce transactivation of AP-1 activity in P+ cells but not in P- cells. Nonphosphorylated forms and TPA- or EGF-induced phosphorylated forms of Erks (Erk1 and Erk2) in P- cells were much lower than those in P+ cells. Stable transfection of wild-type MAPK (Erk2) into P- cells restored its response to TPA and EGF for both AP-1 activation and cell transformation. These results suggest that the shortage of MAPK (Erk1 and Erk2) appears to be an important contributor to the tumor promotion-resistant phenotype in JB6 cells.

Association of semen quality and occupational factors: comparison of case-control analysis and analysis of continuous variables

OBJECTIVE

To compare two statistical approaches, case-control and analysis of continuous parameters of semen, in examining the relationship between occupational exposures and male reproductive function.

DESIGN

Case-control study.

SETTING

Males providing semen samples at a university infertility clinic.

PATIENT(S)

Nonvasectomized males who provided at least one semen sample at an infertility clinic.

MAIN OUTCOME MEASURE(S)

Standard clinical semen analysis.

RESULT(S)

Analyses using a dichotomous dependent variable did not uncover significant associations between any occupational factor and infertility case status. However, linear models incorporating continuous variables identified a number of occupational factors that were associated with specific parameters of semen. A reduction in percentage of progressive sperm and an increase in percentage of coiled tail sperm defects in welders, compared with unexposed subjects, were found. Significant dose-response relationships between level of perceived job stress and percentage of progressive sperm, total motile count, morphology, abnormal heads, and coiled tail defects were found.

CONCLUSION(S)

The findings suggest that subtle changes in semen variables, possibly associated with workplace exposure, may be detected only with parametric analyses of continuous variables of semen.

Mcm2 is a target of regulation by Cdc7-Dbf4 during the initiation of DNA synthesis

The initiation of DNA synthesis is an important cell cycle event that defines the beginning of S phase. This critical event involves the participation of proteins whose functions are regulated by cyclin dependent protein kinases (Cdks). The Mcm2-7 proteins are a family of six conserved proteins that are essential for the initiation of DNA synthesis in all eukaryotes. In Saccharomyces cerevisiae, members of the Mcm2-7 family undergo cell cycle-specific phosphorylation. Phosphorylation of Mcm proteins at the beginning of S phase coincides with the removal of these proteins from chromatin and the onset of DNA synthesis. In this study, we identified DBF4, which encodes the regulatory subunit of a Cdk-like protein kinase Cdc7-Dbf4, in a screen for second site suppressors of mcm2-1. The dbf4 suppressor mutation restores competence to initiate DNA synthesis to the mcm2-1 mutant. Cdc7-Dbf4 interacts physically with Mcm2 and phosphorylates Mcm2 and three other members of the Mcm2-7 family in vitro. Blocking the kinase activity of Cdc7-Dbf4 at the G1-to-S phase transition also blocks the phosphorylation of Mcm2 at this defined point of the cell cycle. Taken together, our data suggest that phosphorylation of Mcm2 and probably other members of the Mcm2-7 proteins by Cdc7-Dbf4 at the G1-to-S phase transition is a critical step in the initiation of DNA synthesis at replication origins.

Behavioural and electrophysiological evidence supporting a role for group I metabotropic glutamate receptors in the mediation of nociceptive inputs to the rat spinal cord

A combined study of behavioural and electrophysiological tests was carried out in order to assess the role of metabotropic glutamate receptors (mGluRs) in mediating sensory inputs to the spinal cord of the rat. In the behavioural study the responses of conscious animals, with or without carrageenan-induced inflammation, to noxious mechanical and thermal stimuli were observed both before and after the intrathecal administration of mGluR antagonists L(+)-2-amino-3-phosphonopropionic acid (L-AP3) and (S)-4-carboxy-3-hydroxyphenylglycine (CHPG). It was found that the mGluR antagonist (S)-CHPG was capable of increasing both mechanical threshold and thermal latency in both groups of animals, and L-AP3 did so in those with inflammation induced in their hindpaw. Following this study, the responses of single lamina III-V dorsal horn neurons to an innocuous A beta fibre brush stimulus and a noxious C fibre (mustard oil) stimulus were extracellularly recorded and the effect of ionophoretically applied drugs was examined. Cyclothiazide (CTZ), a selective antagonist at mGluR1, markedly reduced the activity evoked by mustard oil, but not that elicited by brushing of the receptive field. Activity induced in dorsal horn neurons by ionophoresing various mGluR subgroup agonists was examined. CTZ successfully inhibited the activity evoked by group I mGluR agonist 3,5-dihydroxyphenylglycine (DHPG). In comparison to the neurons which responded to the ionophoresis of DHPG, less were activated by the selective mGluR5 agonist trans-azetidine dicarboxylic acid (t-ADA). Together these results indicate that group I mGlu receptors, in particular mGluR1, play a crucial role in mediating nociception, particularly following a sustained noxious input.

Increased presence of CD34+ cells in the peripheral blood of head and neck cancer patients and their differentiation into dendritic cells

Patients with head and neck squamous cell carcinoma (HNSCC) have profound immune deficiencies. In 65% of these patients, there is an increased intra-tumoral presence of immune-suppressive CD34+ progenitor cells. The goal of the present study was to determine whether CD34+ cell levels were also increased in the peripheral blood of HNSCC patients and if these immune-suppressive cells could be differentiated into dendritic cells. Our results showed that CD34+ cell levels are increased in the peripheral blood of HNSCC patients. To assess if these CD34+ cells could differentiate into dendritic cells, they were isolated from the blood of HNSCC patients and cultured for 12 days with various cytokine combinations. Culturing CD34+ cells with stem cell factor (c-kit ligand) plus granulocyte-macrophage colony-stimulating factor resulted in the appearance of a significant proportion of cells expressing phenotypic markers characteristic of dendritic cells. Also, including tumor necrosis factor-alpha yielded a significant proportion of cells resembling the bipotential precursor cells for dendritic cells and monocytes (CD14+CD1a+), in addition to the dendritic-like cells. When the differentiation inducer 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] was added along with the cytokine combinations, the yield of cells having characteristics of dendritic cells was further increased. Cells that were derived from CD34+ cell cultures containing 1,25(OH)2D3 had a more potent capacity to present the recall antigen tetanus toxoid to autologous peripheral blood leukocytes and to stimulate a mixed leukocyte response compared to cultures to which 1,25(OH)2D3 had not been added. Our results show that CD34+ cells, whose frequency is increased in HNSCC patients, can be differentiated into cells that phenotypically and functionally resemble dendritic cells and that 1,25(OH)2D3 accentuates this differentiation.

Regulation of the steps of angiogenesis by human head and neck squamous cell carcinomas

Human head and neck squamous cell carcinoma (HNSCC) cell cultures were established to identify the angiogenic factors they produced and how these factors contribute to two steps of the angiogenic process: endothelial cell proliferation and migration. The HNSCC cells secreted vascular endothelial cell growth factor (VEGF), transforming growth factor-beta (TGF-beta) and prostaglandin E2 (PGE2), but only low levels of basic fibroblast growth factor. Both proliferation-stimulatory and -inhibitory cytokines were produced by the HNSCC cells, with VEGF promoting endothelial cell proliferation, prostaglandins having no effect and TGF-beta downregulating proliferation. Two methods were used to measure endothelial cell migration: migration into a wound in the endothelial cell monolayer and migration across a filter into lower compartments. HNSCC cell supernatants stimulated endothelial cell migration in both migration models. VEGF had no effect on the motility of endothelial cells. However, when TGF-beta activity in the HNSCC supernatants was neutralized with antibody or the production of prostaglandins by HNSCC cells was blocked with indomethacin, the migration-stimulatory activity in the HNSCC cell supernatants was diminished. Adding authentic PGE2 or TGF-beta 1 to endothelial cells mimicked the migration-stimulatory activity of the HNSCC supernatants. Thus, HNSCC-derived VEGF is important in stimulating endothelial cell proliferation, while the antiproliferative effect of TGF-beta and the migration-stimulatory activity of TGF-beta and PGE2 suggest their having a role in the morphogenic processes of angiogenesis.

Vitamin D3 and ceramide reduce the invasion of tumor cells through extracellular matrix components by elevating protein phosphatase-2A

Increasing phosphorylation reactions by protein kinase A (PKA) or reducing dephosphorylation reactions of protein phosphatase-2A (PP-2A) increases the invasiveness of Lewis lung carcinoma (LLC) cells, as measured by their capacity to traverse extracellular matrix (ECM)-coated filters. Metastatic LLC-LN7 variants have reduced PP-2A activity when compared to nonmetastatic LLC-C8 variants. Immunoblotting showed that this reduced level of PP-2A activity was not due to reduced levels of the PP-2A catalytic (C) subunit. The cellular PP-2A activity could be stimulated by addition of C2-ceramide to LLC-LN7 lysates, or by incubating cells with either C2-ceramide or with a noncalcemic analog of vitamin D3, which has previously been shown to stimulate the release of ceramide. These treatments to elevate PP-2A activity in metastatic LLC-LN7 cells resulted in a decline in their capacity to invade through select (ECM) components, particularly through vitronectin and laminin. Underscoring the importance of PP-2A in limiting the invasiveness of tumor cells was the demonstration that LLC-LN7 cell transfectants overexpressing the PP-2A C alpha subunit were less invasive through ECM components than the wild-type cells. Invasion by these cells was further reduced by additionally increasing PP-2A activity by incubation with C2-ceramide or the vitamin D3 analog. These results suggest a role of a vitamin D3/ceramide/PP-2A pathway in limiting the invasiveness of tumor cells through select ECM components.

Protein phosphatases-1 and -2A regulate tumor cell migration, invasion and cytoskeletal organization

The role of protein kinase A (PKA) and protein phosphatases (PP) -1 and -2A in regulating the metastatic phenotype of Lewis lung carcinoma (LLC) cells was evaluated. The metastatic LLC-LN7 cells were more motile and invasive than were nonmetastatic LLC-C8 cells. Compared to the nonmetastatic cells, the LLC-LN7 cells had increased PKA activity and a deficiency in PP-2A. Nonmetastatic LLC-C8 cells became migratory and invasive when PP-1 and P-2A activities were inhibited with okadaic acid. This stimulation of LLC-C8 motility was tempered by PKA inhibition. Also examined was if the okadaic acid-stimulated LLC-C8 motility was associated with a change in the cytoskeletal organization to that typical of metastatic cells. Treatment of nonmetastatic LLC-C8 cells with okadaic acid caused a redistribution of F-actin toward the periphery of the cells, and eventually to a loss of the filamentous actin network. All of these effects were reversed upon removal of okadaic acid. Our results show that PP-1/2A maintain reduced motility and increased cytoskeletal organization within nonmetastatic LLC cells.

Heparin-binding growth factor(s) derived from head and neck squamous cell carcinomas induce endothelial cell proliferations

BACKGROUND

Tumor growth is dependent on the expansion and proliferation of the host vascular system into the primary neoplasm (angiogenesis). The development of an intact vascular system requires migration and proliferation of endothelial cells and assembly into microvessels. Previous studies in our laboratory demonstrated that head and neck squamous cell carcinomas (HNSCC) are angiogenic in vivo. To clarify the mechanism of HNSCC-induced angiogenesis, the present study sought to determine if HNSCCs produced endothelial cell mitogens in vitro.

METHODS

Production of PGE-2, TGF-beta, FGF-2 (basic-FGF [fibroblast growth factor]), and vascular endothelial cell growth factor (VEGF) were quantitated by enzyme-linked immunoabsorbant assay (ELISA) in five HNSCC lines. Cell free supernatants of 5 HNSCC lines were tested in a nonradioactive proliferation assay using human umbilical vein endothelial cells (HUVECs).

RESULTS

All lines demonstrated enhanced endothelial cell proliferation in a dose-dependent fashion. Fractionation of these supernatants by heparin column chromatography significantly reduced endothelial cell proliferation in the five lines tested (range, 31.7% to 46.23% reduction; mean, 38.14+/-6.02%). Pretreatment with antibody to VEGF but not transforming growth factor (TGF)-beta inhibited endothelial cell proliferation.

CONCLUSIONS

These studies indicate HNSCCs produce factor(s) which stimulate endothelial cell proliferation and that VEGF may be involved in HNSCC-induced endothelial cell mitogenesis.

Nuclear accumulation of Saccharomyces cerevisiae Mcm3 is dependent on its nuclear localization sequence

BACKGROUND

The proteins of the Mcm2-7 family are required for the initiation of DNA replication. In Saccharomyces cerevisiae the nuclear envelope does not break down during the mitotic phase of the cell cycle. Large nuclear proteins, such as the Mcm proteins, which accumulate in the nucleus during specific portions of the cell cycle, must have regulated mechanisms to direct their entry into the nucleus.

RESULTS

We have identified a nuclear localization sequence (NLS) in Mcm3, and demonstrated that it is necessary for the translocation of Mcm3 into the nucleus and sufficient for directing Escherichia coli beta-galactosidase to the nucleus. Immediately adjacent to the nuclear localization sequence are four potential sites for phosphorylation by Cdc28. Mutagenesis of all four sites has no immediate phenotypic effect on cell growth or viability, nor does it affect nuclear accumulation of Mcm3, although two-dimensional protein gel analysis has shown that at least some of these sites are normally phosphorylated in vivo. Substitution of the Mcm3 NLS by the SV40 large T-antigen NLS also directs the nuclear accumulation of the Mcm3-T-antigen protein, although cell growth is compromised. Replication activity in cells bearing either the Mcm3-Cdc28 phosphorylation site mutations or the Mcm3 T-antigen NLS substitution, as measured by plasmid stability assays, is comparable to activity in wild-type cells.

CONCLUSIONS

The Mcm3 protein is imported into the nucleus by a specific NLS. The cell cycle specific nuclear accumulation of Mcm3 appears to be a result of nuclear retention or nuclear targeting, rather than nuclear import regulated through the NLS.

Association of arsenic-induced malignant transformation with DNA hypomethylation and aberrant gene expression

Inorganic arsenic, a human carcinogen, is enzymatically methylated for detoxication, consuming S-adenosyl-methionine (SAM) in the process. The fact that DNA methyltransferases (MeTases) require this same methyl donor suggests a role for methylation in arsenic carcinogenesis. Here we test the hypothesis that arsenic-induced initiation results from DNA hypomethylation caused by continuous methyl depletion. The hypothesis was tested by first inducing transformation in a rat liver epithelial cell line by chronic exposure to low levels of arsenic, as confirmed by the development of highly aggressive, malignant tumors after inoculation of cells into Nude mice. Global DNA hypomethylation occurred concurrently with malignant transformation and in the presence of depressed levels of S-adenosyl-methionine. Arsenic-induced DNA hypomethylation was a function of dose and exposure duration, and remained constant even after withdrawal of arsenic. Hyperexpressibility of the MT gene, a gene for which expression is clearly controlled by DNA methylation, was also detected in transformed cells. Acute arsenic or arsenic at nontransforming levels did not induce global hypomethylation of DNA. Whereas transcription of DNA MeTase was elevated, the MeTase enzymatic activity was reduced with arsenic transformation. Taken together, these results indicate arsenic can act as a carcinogen by inducing DNA hypomethylation, which in turn facilitates aberrant gene expression, and they constitute a tenable theory of mechanism in arsenic carcinogenesis.

Mcm2 and Mcm3 are constitutive nuclear proteins that exhibit distinct isoforms and bind chromatin during specific cell cycle stages of Saccharomyces cerevisiae

The Mcm2-7 proteins are a family of conserved proteins whose functions are essential for the initiation of DNA synthesis in all eukaryotes. These patients are constitutively present in high abundance in actively proliferating cells. In Saccharomyces cerevisiae, the intracellular concentrations of Mcms are between 100 and 500 times the number of replication origins. However, these proteins are limiting for the initiation of DNA synthesis at replication origins. Our studies indicate that only a small fraction of Mcm2 and Mcm3 tightly associates with chromatin, from late M phase to the beginning of the S phase. The rest of the Mcm2 and Mcm3 proteins are disturbed to both the cytoplasm and nucleoplasm in relatively constant levels throughout the cell cycle. We also show that S. cerevisiae Mcm3 is a phosphoprotein that exists in multiple isoforms and that distinct isoforms of Mcm2 and Mcm3 can be detected at specific stages of the cell cycle. These results suggest that the localization and function of the Mcm proteins are regulated by posttranslational phosphorylation in a manner that is consistent with a role for the Mcm proteins in restricting DNA replication to once per cell cycle.

Myeloid differentiation treatment to diminish the presence of immune-suppressive CD34+ cells within human head and neck squamous cell carcinomas

Within human head and neck squamous cell carcinomas (HNSCC) that produce granulocyte-macrophage CSF are CD34+ cells that exhibit natural suppressive (NS) activity. The present study aimed to identify how these NS cells mediate suppression and how to diminish their presence. CD34+ cells that were immunomagnetically isolated from fresh surgical HNSCC specimens produced a soluble product that blocked normal T cell stimulation through the TCR/CD3 complex. This inhibitory activity could be neutralized with Abs to TGF-beta1. Since prior studies showed that the CD34+ NS cells within HNSCC cancers are myelomonocytic progenitor cells, the feasibility of using cytokines that can induce myeloid cell differentiation to diminish the presence of CD34+ NS cells was tested. Adding low doses of 100 U/ml IFN-gamma plus 10 U/ml TNF-alpha to bulk cultures of dissociated HNSCC cancers diminished the frequency of CD34+ cells. Studies with CD34+ cells that were isolated from the HNSCC cancers showed that this cytokine treatment induced differentiation of the CD34+ cells predominantly into monocytic cells. The consequence of treating CD34+ NS cells with the myeloid differentiation treatment was the loss of suppressive activity, a decline in TGF-beta production, and the production of TNF-alpha by the resulting monocytic cells. In HNSCC bulk cultures containing high levels of CD34+ NS activity, IFN-gamma/TNF-alpha not only reduced CD34+ cell levels, but also increased the capacity of the intratumoral T cells to express the p55 IL-2R. These studies show that IFN-gamma/TNF-alpha can induce differentiation of TGF-beta-secreting CD34+ NS cells into nonsuppressive monocytic cells that secrete TNF-alpha.

Myeloid differentiation treatment to diminish the presence of immune-suppressive CD34+ cells within human head and neck squamous cell carcinomas

Within human head and neck squamous cell carcinomas (HNSCC) that produce granulocyte-macrophage CSF are CD34+ cells that exhibit natural suppressive (NS) activity. The present study aimed to identify how these NS cells mediate suppression and how to diminish their presence. CD34+ cells that were immunomagnetically isolated from fresh surgical HNSCC specimens produced a soluble product that blocked normal T cell stimulation through the TCR/CD3 complex. This inhibitory activity could be neutralized with Abs to TGF-beta1. Since prior studies showed that the CD34+ NS cells within HNSCC cancers are myelomonocytic progenitor cells, the feasibility of using cytokines that can induce myeloid cell differentiation to diminish the presence of CD34+ NS cells was tested. Adding low doses of 100 U/ml IFN-gamma plus 10 U/ml TNF-alpha to bulk cultures of dissociated HNSCC cancers diminished the frequency of CD34+ cells. Studies with CD34+ cells that were isolated from the HNSCC cancers showed that this cytokine treatment induced differentiation of the CD34+ cells predominantly into monocytic cells. The consequence of treating CD34+ NS cells with the myeloid differentiation treatment was the loss of suppressive activity, a decline in TGF-beta production, and the production of TNF-alpha by the resulting monocytic cells. In HNSCC bulk cultures containing high levels of CD34+ NS activity, IFN-gamma/TNF-alpha not only reduced CD34+ cell levels, but also increased the capacity of the intratumoral T cells to express the p55 IL-2R. These studies show that IFN-gamma/TNF-alpha can induce differentiation of TGF-beta-secreting CD34+ NS cells into nonsuppressive monocytic cells that secrete TNF-alpha.

Inhibition of tumor invasiveness by 1alpha,25-dihydroxyvitamin D3 coupled to a decline in protein kinase A activity and an increase in cytoskeletal organization

The capacity of cloned metastatic Lewis lung carcinoma cells (LLC-LN7) to invade through reconstituted basement membrane-coated filters was reduced after incubation with 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3]. This was observed at doses as low as 10(-10) M 1,25(OH)2D3. The 1,25(OH)2D3-treated cells also had reduced levels of protein kinase A (PKA) activity and an increase in the level of polymerized actin, properties that have previously been demonstrated for less metastatic LLC variants. In addition, levels of the intermediate filament protein vimentin increased in 1,25(OH)2D3-treated LLC-LN7 tumor cells. In contrast, the levels and distribution of tubulin were not affected by 1,25(OH)2D3. The possibility that the decline in PKA activity was involved in the 1,25(OH)2D3 modulation of the cytoskeletal components was evaluated. To accomplish this, LLC-7 transfectants whose PKA levels were blocked due to expression of a mutated PKA R(1alpha) subunit (LN7-REV) were incubated with 1,25(OH)2D3 and their levels of F-actin were measured. In the absence of 1,25(OH)2D3 treatment, the PKA-defective LN7-REV cells had an increased level of polymerized actin as compared to the wild-type LLC-LN7 cells. This level of F-actin was minimally affected by 1,25(OH)2D3, suggesting that PKA activity is required for 1,25(OH)2D3 modulation of actin polymerization. These studies show that 1,25(OH)2D3 can reduce PKA activity in tumor cells, and that this reduction in PKA may be an intermediate signal through which 1,25(OH)2D3 affects the cytoskeleton and diminishes tumor invasiveness.

Correlation of middle meatal and maxillary sinus cultures in acute maxillary sinusitis

Cultures obtained from the middle meatus have been used frequently in the past to direct therapy in patients with acute maxillary sinusitis. However, no convincing data have been published to indicate that middle meatal cultures accurately represent the bacterial flora within the maxillary sinus. The hypothesis of this experiment is that bacteria obtained by directed middle meatal cultures qualitatively and quantitatively correlate with cultures taken by maxillary sinus puncture. Acute sinusitis was induced by injecting 10(8) colony-forming units of bacteria directly into the maxillary sinuses of rabbits in which the ostia were occluded with cotton packs. Eight animals were injected with Staphylococcus aureus, eight with Haemophilus influenzae, and eight with Streptococcus pneumoniae. The packs were removed after 3 days, and specimens were obtained from the middle meatus in the region of the maxillary sinus ostium, and from the maxillary sinus, 1 day later. The contralateral maxillary sinuses of six of the animals were injected with normal saline and served as controls. There was a 100% correlation rate between cultures of specimens obtained from the maxillary sinus and from the middle meatus in all 24 animals. In addition, the quantitative counts from the middle meatus and the maxillary sinus correlated. Control animals showed no bacterial growth from either the middle meatus or the maxillary sinus. These results show that, in an animal model of acute sinusitis, cultures of specimens from the middle meatus reflect the contents of the maxillary sinus.

Increased recurrence and metastasis in patients whose primary head and neck squamous cell carcinomas secreted granulocyte-macrophage colony-stimulating factor and contained CD34+ natural suppressor cells

Human head and neck squamous cell carcinomas (HNSCC) that produce high levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) have been shown to contain CD34+ natural suppressor cells that inhibit the activity of intratumoral T-cells. The present study evaluated whether GM-CSF production and the presence of CD34+ cells within primary HNSCC would translate into increased recurrence, metastasis or cancer-related death during the 2 years following surgical excision. Freshly excised primary HNSCC of 20 patients that subsequently developed disease, and of 17 patients that remained with no evidence of disease were analyzed for production of GM-CSF and for CD34+ cell content. The cancers of patients that subsequently developed recurrences or metastatic disease produced almost 4-fold the levels of GM-CSF and had approximately 2.5-fold the number of CD34+ cells as did cancers of patients that remained disease-free. In a second method of analysis, the prognostic significance of high vs. low GM-CSF and CD34+ cell values was evaluated. These analyses showed that patients whose cancers produced high GM-CSF levels or had a high CD34+ cell content had a disproportionately high incidence of recurrence or metastatic disease (94% and 100%, respectively), while the majority of patients whose primary cancers produced low levels of GM-CSF or had a low CD34+ cell content remained disease-free (16% and 19%, respectively). Our results indicate that the presence of CD34+ cells in GM-CSF-producing HNSCC is associated with a poorer prognosis for the cancer patients and suggest the utility of these parameters as prognostic indicators of outcome. Mechanistically, our results suggest that the presence of immune suppressive CD34+ cells in GM-CSF-producing HNSCC leads to increased tumor recurrence or metastasis.

Protein phosphatase-2A association with microtubules and its role in restricting the invasiveness of human head and neck squamous cell carcinoma cells

The role of protein phosphatase-2A (PP-2A) in regulating the motility and adhesion of human head and neck squamous cell carcinomas (HNSCC) was investigated. Immunofluorescent staining of these HNSCC cells showed PP-2A can co-localize with microtubules. That the PP-2A influences motility was shown by the increase in HNSCC cell migration through laminin and vitronectin when PP-2A was selectively inhibited with low dose okadaic acid, and by the reduction in invasion through these same matrix components by elevators of PP-2A activity. Motility of HNSCC cells through collagen I or fibronectin was not modulated by PP-2A. The reduction in HNSCC migration through vitronectin or laminin that resulted from treatment with PP-2A elevators was associated with an increase in cellular adhesiveness to these same ECM components. These studies show the association of PP-2A with the cellular cytoskeleton and its role in restricting the invasiveness of tumor cells through select extracellular matrix components.

Increased interleukin-6 production by cerebral cortical tissue of adult versus young mice

The cytokine interleukin-6 (IL-6) has been implicated as a contributor to injury in several neurological disorders. The amounts of IL-6 released by the cerebral cortical tissue of mice of varying maturational age groups were measured and found to increase with age. Specifically, the basal level of IL-6 released from the tissue of infant (less than 2 weeks old) mice was low, although the tissue could be readily stimulated to secrete high levels of IL-6. Higher levels of IL-6 were released from young adult (2 month old) mice. Adult mice that were either 6 or 9 months of age secreted significantly higher levels of IL-6 compared to the tissue of either the young adult or infant animals, although the difference between levels secreted by the 6- or 9-month old groups was minimal. IL-6 production by adult cerebral cortical tissue could be further stimulated, but it was less readily achieved compared to the tissue of infants. In response to the negative regulator transforming growth factor-beta (TGF-beta), the levels of IL-6 released by stimulated cerebral cortical tissue of infants, as well as by unstimulated and stimulated tissue of adults, were reduced to the low basal levels of IL-6 produced by infant tissue. These results suggest that normal development and aging are correlated with an increase in IL-6 production that may be due to shifts in levels of stimulatory or inhibitory regulatory controls, but not to an inability of young tissue to produce IL-6 or to a lack of responsiveness of adult tissue to negative regulatory control by TGF-beta.