Evaluation of a mucoadhesive fenretinide patch for local intraoral delivery: a strategy to reintroduce fenretinide for oral cancer chemoprevention

Systemic delivery of fenretinide in oral cancer chemoprevention trials has been largely unsuccessful due to dose-limiting toxicities and subtherapeutic intraoral drug levels. Local drug delivery, however, provides site-specific therapeutically relevant levels while minimizing systemic exposure. These studies evaluated the pharmacokinetic and growth-modulatory parameters of fenretinide mucoadhesive patch application on rabbit buccal mucosa. Fenretinide and blank-control patches were placed on right/left buccal mucosa, respectively, in eight rabbits (30 min, q.d., 10 days). No clinical or histological deleterious effects occurred. LC-MS/MS analyses of post-treatment samples revealed a delivery gradient with highest fenretinide levels achieved at the patch-mucosal interface (no metabolites), pharmacologically active levels in fenretinide-treated oral mucosa (mean: 5.65 μM; trace amounts of 4-oxo-4-HPR) and undetectable sera levels. Epithelial markers for cell proliferation (Ki-67), terminal differentiation (transglutaminase 1-TGase1) and glucuronidation (UDP-glucuronosyltransferase1A1-UGT1A1) exhibited fenretinide concentration-specific relationships (elevated TGase1 and UGT1A1 levels <5 μM, reduced Ki-67 indices >5 μM) relative to blank-treated epithelium. All fenretinide-treated tissues showed significantly increased intraepithelial apoptosis (TUNEL) positivity, implying activation of intersecting apoptotic and differentiation pathways. Human oral mucosal correlative studies showed substantial interdonor variations in levels of the enzyme (cytochrome P450 3A4-CYP3A4) responsible for conversion of fenretinide to its highly active metabolite, 4-oxo-4-HPR. Complementary in vitro assays in human oral keratinocytes revealed fenretinide and 4-oxo-4-HPR's preferential suppression of DNA synthesis in dysplastic as opposed to normal oral keratinocytes. Collectively, these data showed that mucoadhesive patch-mediated fenretinide delivery is a viable strategy to reintroduce a compound known to induce keratinocyte differentiation to human oral cancer chemoprevention trials.

Effects of human oral mucosal tissue, saliva, and oral microflora on intraoral metabolism and bioactivation of black raspberry anthocyanins

Our oral cancer chemoprevention trial data implied that patient-specific differences in local retention and metabolism of freeze-dried components of black raspberries (BRB) affected therapeutic responsiveness. Subsequent studies have confirmed that anthocyanins are key contributors to BRB's chemopreventive effects. Consequently, functional assays, immunoblotting, and immunohistochemical analyses to evaluate levels and distribution of BRB anthocyanin-relevant metabolic enzymes in human oral tissues were conducted. Liquid chromatography/tandem mass spectrometry (LC/MS-MS) analyses of time course saliva samples collected following BRB rinses were conducted to assess local pharmacokinetics and compare the capacities of three different BRB rinse formulations to provide sustained intraoral levels of anthocyanins. Protein profiles showed the presence of key metabolic enzymes in all 15 oral mucosal tissues evaluated, whereas immunohistochemistry confirmed these enzymes were distributed within surface oral epithelia and terminal salivary ducts. β-Glucosidase assays confirmed that whole and microflora-reduced saliva can deglycosylate BRB anthocyanins, enabling generation of the bioactive aglycone, cyanidin. LC/MS-MS analyses showed retention of parent anthocyanins and their functional, stable metabolite, protocatechuic acid, in saliva for up to 4 hours after rinsing. Furthermore, postrinse saliva samples contained glucuronidated anthocyanin conjugates, consistent with intracellular uptake and phase II conversion of BRB anthocyanins into forms amenable to local recycling. Our data show that comparable to the small intestine, the requisite hydrolytic, phase II and efflux transporting enzymes necessary for local enteric recycling are present and functional in human oral mucosa. Notably, interpatient differences in anthocyanin bioactivation and capacities for enteric recycling would impact treatment as retention of bioactivated chemopreventives at the target site would sustain therapeutic effectiveness.

Abstract 3375: The epithelial to endotheliod transition (EET): A cellular modulation that promotes the head and neck squamous cell carcinoma tumorigenic phenotype

The presence of the EMT (epithelial-mesenchymal transition) and EndMT (endothelial-mesenchymal transition) demonstrates the extent of phenotypic plasticity in cancers. Previous findings in head and neck squamous cell carcinoma (HNSCC) cells, i.e., VEGF's autocrine-paracrine function and their responsiveness to endostatin, imply that HNSCC cells share some functional characteristics with endothelial cells and suggest the potential for an “epithelial-to-endotheliod transition (EET)”. Such a transition would facilitate HNSCC tumorigenesis by augmenting release of proangiogenic factors and facilitating tumor cell migration and invasion. Consequently, these studies elucidated whether or not an EET occurs in HNSCC cells and tumors, and evaluated cellular parameters to uniquely characterize this epithelial-endotheliod transition. Our results demonstrate that cultured HNSCC cells express a variety of endothelial-specific markers, and assumption of the endotheliod phenotype has functional consequences including uptake of acetylated low density lipoprotein and enhanced invasion and migration. Selective HNSCC cells were also highly responsive to transforming growth factor-β1 and express its auxiliary receptor, endoglin. Furthermore, the EET is not restricted to cultured HNSCC cells per se as tumor cells in resected human HNSCC tumors and proliferating epithelia at the margins of ulcers demonstrate a similar phenotype. These data suggest that, similar to EMT, the EET enhances epithelial cell migration. Also, the regulation of this transition-transient (wound healing) versus sustained (invasive cancers)-impacts clinical outcome. Finally, recognition of the EET as a distinct entity provides impetus for future clinical trials to concurrently assess the antitumorigenic as well as the angiostatic properties of therapeutic agents formally regarded as exclusively angiostatic in scope.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3375. doi:10.1158/1538-7445.AM2011-3375

Nanoparticles for local drug delivery to the oral mucosa: proof of principle studies

Purpose

To determine if solid lipid nanoparticles represent a viable strategy for local delivery of poorly water soluble and unstable chemopreventive compounds to human oral tissues.

Methods

Nanoparticle uptake and compound retention evaluations employed monolayer-cultured human oral squamous cell carcinoma (OSCC) cell lines and normal human oral mucosal explants. Feasibility of nanoparticle delivery was also evaluated with respect to the presence of phase-III efflux transporters in normal oral mucosal tissue and OSCC tissues.

Results

Functional uptake assays confirmed significantly greater internalization of nanoparticle-delivered fluorescent probe relative to free-fluorescent probe delivery, while concurrently demonstrating nanoparticle uptake rate differences among the OSCC cell lines and the phagocytic control human monocyte cell line. Mucosal explants exhibited nanoparticle penetration and internalization in the spinous and basal epithelial layers (7/10 specimens), and also exhibited the presence of the phase-III efflux transporters multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP).

Conclusions

These data confirm nanoparticle internalization by OSCC cells and support the premise that nanoparticle-based delivery provides higher final intracellular levels relative to bolus administration. Furthermore, the penetration and subsequent internalization of nanoparticles within the proliferating basal layer cells demonstrates the feasibility of nanoparticle formulations for local delivery and stabilization of oral chemopreventive compounds.

A rapid and sensitive LC-MS/MS method for quantification of four anthocyanins and its application in a clinical pharmacology study of a bioadhesive black raspberry gel

Cyanidin 3-glucoside (C3GLU), cyanidin 3-rutinoside (C3RUT), cyanidin 3-sambubioside (C3SAM) and cyanidin 3-(2(G)-xylosyl) rutinoside (C3XRUT) are the four constituent black raspberry anthocyanins that contribute significantly to the chemopreventive effects of freeze-dried black raspberries (FBR). A highly sensitive and specific LC-MS/MS assay was developed and validated to simultaneously quantify these four FBR anthocyanins in human saliva, plasma and oral tissue homogenates. In saliva, the lower limit of quantification (LLOQ) for these anthocyanins was 1.0 ng/mL. The within-run and between-run coefficients of variations (CVs) at the quality control concentrations (1.0, 5.0, 50 and 500 ng/mL) were all <12%, except for C3SAM and C3RUT at the LLOQ, which showed a within-run CV of 18.3% and between-run CV of 16.0%, respectively. The accuracy values ranged from 87.5 to 110%. In plasma, the LLOQ for C3GLU and C3RUT was 1.0 ng/mL and for C3SAM 5.0 ng/mL. The CVs at the above concentrations were <15%, except for C3GLU at the LLOQ, which showed the between-run CV of 16.9%. The accuracy values ranged from 90.7% to 112.7% except for C3GLU at the LLOQ, which showed 119.3%. In tissue homogenates, the LLOQ for C3GLU and C3RUT was 2.0 ng/mL, and C3SAM 5.0 ng/mL. The CVs and accuracy values at concentrations (2.0, 5.0, 50 and 500 ng/mL) were similar to those in human plasma. This assay was subsequently used in a pilot pharmacology study to evaluate the effects of topical application of a 10% (w/w) FBR bioadhesive gel to selected mucosal sites in the posterior mandibular gingiva. Measurable saliva and tissue levels of the FBR anthocyanins confirmed that gel-delivered anthocyanins are readily distributed to saliva and easily penetrate human oral mucosa.

Human head and neck squamous cell carcinoma cells are both targets and effectors for the angiogenic cytokine, VEGF

Former vascular endothelial growth factor (VEGF)-head and neck squamous cell carcinoma (HNSCC) studies have focused on VEGF's contributions toward tumor-associated angiogenesis. Previously, we have shown that HNSCC cells produce high levels of VEGF. We therefore hypothesized that VEGF serves a biphasic role, that is, pro-angiogenic and pro-tumorigenic in HNSCC pathogenesis. Western blots confirmed the presence of VEGF's primary mitogenic receptors, VEGFR-2/KDR and VEGFR-1/Flt-1 in cultured HNSCC cells. Subsequent studies evaluated VEGF's effects on HNSCC intracellular signaling, mitogenesis, invasive capacities, and matrix metalloproteinases (MMPs) activities. Introduction of hrVEGF(165) initiated ROS-mediated intracellular signaling, resulting in kinase activation and phosphorylation of KDR and Erk1/2. As high endogenous VEGF production rendered HNSCC cells refractory to exogenous VEGF's mitogenic effects, siRNA was employed, inhibiting endogenous VEGF production for up to 96 h. Relative to transfection vector matched controls, siRNA treated HNSCC cells showed a significant decrease in proliferation at both 30 and 50 nM siRNA doses. Addition of exogenous hrVEGF(165) (30 and 50 ng/ml) to siRNA-silenced HNSCC cells resulted in dose-dependent increases in cell proliferation. Cell invasion assays showed VEGF is a potent HNSCC chemoattractant and demonstrated that VEGF pre-treatment enhanced invasiveness of HNSCC cells. Conditioned media from VEGF challenged HNSCC cells showed a moderate increase in gelatinase activity. Our results demonstrate, for the first time, that HNSCC cells are both targets and effectors for VEGF. These data introduce the prospect that VEGF targeted therapy has the potential to fulfill both anti-angiogenic and anti-tumorigenic functions.

Topical application of a bioadhesive black raspberry gel modulates gene expression and reduces cyclooxygenase 2 protein in human premalignant oral lesions

Reduced expression of proapoptotic and terminal differentiation genes in conjunction with increased levels of the proinflammatory and angiogenesis-inducing enzymes, cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS), correlate with malignant transformation of oral intraepithelial neoplasia (IEN). Accordingly, this study investigated the effects of a 10% (w/w) freeze-dried black raspberry gel on oral IEN histopathology, gene expression profiles, intraepithelial COX-2 and iNOS proteins, and microvascular densities. Our laboratories have shown that freeze-dried black raspberries possess antioxidant properties and also induce keratinocyte apoptosis and terminal differentiation. Oral IEN tissues were hemisected to provide samples for pretreatment diagnoses and establish baseline biochemical and molecular variables. Treatment of the remaining lesional tissue (0.5 g gel applied four times daily for 6 weeks) began 1 week after the initial biopsy. RNA was isolated from snap-frozen IEN lesions for microarray analyses, followed by quantitative reverse transcription-PCR validation. Additional epithelial gene-specific quantitative reverse transcription-PCR analyses facilitated the assessment of target tissue treatment effects. Surface epithelial COX-2 and iNOS protein levels and microvascular densities were determined by image analysis quantified immunohistochemistry. Topical berry gel application uniformly suppressed genes associated with RNA processing, growth factor recycling, and inhibition of apoptosis. Although the majority of participants showed posttreatment decreases in epithelial iNOS and COX-2 proteins, only COX-2 reductions were statistically significant. These data show that berry gel application modulated oral IEN gene expression profiles, ultimately reducing epithelial COX-2 protein. In a patient subset, berry gel application also reduced vascular densities in the superficial connective tissues and induced genes associated with keratinocyte terminal differentiation.

Functional activities and immunohistochemical cellular distribution of glutathione s-transferases in normal, dysplastic, and squamous cell carcinoma human oral tissues

Clinical data show a strong correlation between tobacco and alcohol use and the development of oral squamous cell carcinoma (SCC). While this association implies that the oral mucosa actively metabolizes carcinogens, there is little information which depicts the carcinogen metabolizing enzymes within the oral cavity. Glutathione S-transferases (GSTs) primary function is to detoxify carcinogens by increasing their water solubility, GSTs represent key carcinogen metabolizing enzymes. Notably, individuals with a null phenotype for certain GST isoforms are at an increased risk to develop cancer. This study investigated the function and distribution of GSTs in human oral tissues. Our results from this pilot study showed a trend towards higher GST activities in SCC tissues relative to normal mucosa. Also, relative to normal tissues, the SCC and epithelial dysplasia samples showed a more intense and uniform GST intracellular distribution. GST activities are increased in many high grade cancers. Similarly, our data suggest that GST upregulation occurs in at least a subset of precancerous and malignant oral lesions.

The effects of reactive species on the tumorigenic phenotype of human head and neck squamous cell carcinoma (HNSCC) cells

Sustained inflammation up-regulates the reactive species (RS) generating enzymes inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). While clinical data show that levels of iNOS and COX-2 are increased in epithelium during the transformation of dysplasia to overt head and neck squamous cell carcinoma (HNSCC), the mechanisms by which their overexpression contributes to HNSCC development have not been completely delineated. This study assessed the effects of RS on parameters associated with the HNSCC tumorigenic phenotype inclusive of activation of NF-kappaB (in situ immunostaining and reporter assay) and production of proinflammatory and proangiogenic proteins (ELISA analyses). Our data, which show both reactive oxygen and nitrogen species activated NF-kappaB, and that all RS donors evaluated increased HNSCC cellular production of vascular endothelial growth factor, IL-8 and epidermal growth factor receptor proteins, imply inflammation associated RS promote HNSCC by their abilities to modulate intracellular signaling and affect gene expression.

Rescue of SCID murine ischemic hindlimbs with pH-modified rhbFGF/Poly(DL-lactic-co-glycolic acid) implants

Site-specific controlled release of biologically active angiogenic growth factors such as recombinant human basic fibroblast growth factor (rhbFGF) is a promising approach to improve collateral circulation in patients suffering from ischemic heart disease or peripheral vascular disease. Previously, we demonstrated stabilization of rhbFGF encapsulated in injectable poly(DL-lactic-co-glycolic acid) (PLGA) millicylindrical implants upon co-incorporation of Mg(OH)2 to raise the microclimate pH in the polymer. The purpose of this study was to compare stabilized (S; +Mg(OH)2+other stabilizers), partially stabilized (PS; -Mg(OH)2+other stabilizers), unstabilized (US; no stabilizers), and blank (B) PLGA-encapsulated rhFGF formulations to promote angiogenesis in SCID mice. Following 4 weeks subcutaneous implantation at a 0.1 microg dose in healthy animals, the S group exhibited significantly higher blood vessel density (62+/-17 vessels/mm2) compared with PS, US, and B groups (11+/-2*, 17+/-7*, and 3+/-1** respectively) (* p<0.05; ** p<0.01). Furthermore, the S group developed a thicker granulation layer at the tissue/implant interface relative to the other groups (39+/-7 vs 25+/-2**, 21+/-1***, and 12+/-1 microm*** respectively) (*** p<0.001). After 6 weeks implantation in mice with ischemic hindlimbs, the S group implants also markedly augmented both limb reperfusion (87+/-14%) and limb survival (5/5), whereas ischemic limbs did not recover in PS, US and B groups. Stabilized rhbFGF incorporated in pH modified PLGA millicylinders effectively promotes site-directed in vivo angiogenesis and also enables preservation of ischemic hindlimb function.

Cyclooxygenase-2 directly induces MCF-7 breast tumor cells to develop into exponentially growing, highly angiogenic and regionally invasive human ductal carcinoma xenografts

Based on our studies demonstrating first time evidence that the cyclooxygenase-2 (Cox-2) enzyme is abundant within invasive human breast tumors, we developed a clonally derived human breast tumor cell clone designated as MCF-7/Cox-2 Clone 10 by transfection of human Cox-2 cDNA into slow growing, Cox-2 null, non-metastatic MCF-7 human breast tumor cells. The present studies evaluated the biological characteristics of the MCF-7/Cox-2 Clone 10 human breast tumors compared to the characteristics of MCF-7/empty vector control tumors when grown in vivo following injection of 5x10(6) tumor cells into mammary fat pads of ovariectomized female Crl:Nu-Foxn1(nu) mice implanted with slow release 17-beta estradiol pellets. At 60 days after tumor cell injection, MCF-7/Cox-2 Clone 10 human breast tumors were 4-fold greater (p < 0.01) in volume than MCF-7/empty vector control tumors. MCF-7/Cox-2 Clone 10 human breast tumor xenografts were highly angiogenic based on histological observation of large-bore blood vessels, which was confirmed by immunohistochemical staining with anti-CD-31 antibody and quantitation of mean vessel density. MCF-7/Cox-2 Clone 10 human breast tumor cells were present within regional lymph nodes adjacent to mammary fat pads with their local invasion confirmed by Western blotting of Cox-2-protein. This unique Cox-2-dependent breast tumor model rapidly produces large, angiogenic, locally invasive human breast tumor xenografts in mammary fat pads of ovariectomized female Crl:Nu-Foxn1(nu) mice at 42-60 days which recapitulate human breast ductal carcinomas. This unique model may be invaluable as a means to evaluate preclinical safety and efficacy of novel adjuvant therapies for women with metastastic breast cancer including prostanoid receptor antagonists, newly developed anti-angiogenic therapies, as well as other novel approaches for targeting and destruction of human breast tumors and their vasculature.

Reduced nonprotein thiols inhibit activation and function of MMP-9: implications for chemoprevention

Clinical studies demonstrate a positive correlation between the extent of matrix metalloproteinase (MMP) activation and malignant progression of precancerous lesions. Therefore, identification of effective, well-tolerated MMP inhibitors represents a rational chemopreventive strategy. A variety of agents, including proteinases and thiol-oxidizing compounds, activate MMPs by initiating release of the propeptide's cysteine sulfur "blockage" of the MMP active site. Despite the importance of the propeptide's cysteine thiol in preserving MMP latency, limited studies have evaluated the effects of reduced thiols on MMP function. This study investigated the effects of two naturally occurring nonprotein thiols, i.e., glutathione (GSH) and N-acetylcysteine (NAC), on activation, function, and cellular-extracellular matrix interactions of the basement-membrane-degrading gelatinase, MMP-9. Our results reveal that NAC and GSH employ protein S-thiolation to inhibit organomercurial activation of pro-MMP-9. Gelatinase activity assays showed that GSH and NAC significantly inhibited MMP-9 but not MMP-2 function, implying isoform structural specificity. Immunoblot analyses, which suggested GSH interacts with MMP-9's active-site Zn, were corroborated by computational molecular modeling. Cell invasion assays revealed that NAC enhanced endostatin's ability to inhibit human cancer cell invasion. Collectively, these data demonstrate that nonprotein thiols suppress MMP-9 activation and function and introduce the prospect for their use in chemopreventive applications.

Activation of Akt and mTOR in CD34+/K15+ keratinocyte stem cells and skin tumors during multi-stage mouse skin carcinogenesis

BACKGROUND

The goal of the present studies was to localize two proteins known to be involved in regulation of cell proliferation and survival in specific cell populations in normal SENCAR mouse skin and during multi-stage skin carcinogenesis. The proteins evaluated included activated Akt, as defined by phosphorylation of Akt at Serine-473 (pAkt) and mammalian target of rapamycin (pmTOR), defined by phosphorylation of mTOR at Serine-2448 (pmTOR). The cell populations examined included mouse keratinocyte stem cells (KSCs) within hair follicles and preneoplastic papilloma cells.

MATERIALS AND METHODS

Immunochemical staining analysis as well as triple color immunofluorescence in combination with confocal microscopy were used to evaluate the presence of activated Akt and mammalian target of rapamycin (mTOR) in KSCs within the bulge niche of hair follicles, as identified by expression of the specific markers of mouse KSCs, CD34 and cytokeratin 15 (K15). Western blot analysis was used to examine CD34 and K15 protein levels in dorsal skin isolated from SENCAR mice during multi-stage skin carcinogenesis.

RESULTS

CD34+/K15+ KSCs were located only in the outer root sheath (ORS) of a specific niche within hair follicles defined as "the bulge". The location of CD34+/K15+ KSCs remained restricted to the bulge region throughout the 22-week time-period examined during which pre-malignant papillomas developed and rapidly expanded. There was a significant decrease in K15 protein levels at 24 h and 15 weeks in dorsal skin treated with DMBA/TPA compared to CD34 protein levels. CD34+ cells within the numerous hair follicles in hyperplastic skin were found to undergo proliferation during the process of multi-stage skin carcinogenesis based on their staining with antibodies directed against proliferating cell nuclear antigen (PCNA). While pAkt was present within the bulge region of hair follicles, pmTOR was present in cells in the ORS of the bulge region as well as the upper infundibulum of hair follicles in dorsal skin treated with acetone. Within papillomas tissues isolated at 15 weeks following DMBA/TPA treatment, pAkt was localized to suprabasal cells with nominal staining of pAkt in the basal cell layer. There were fewer cells within the basal cell layer that contained pmTOR, in addition to the presence of pmTOR in suprabasal cells within papillomas.

CONCLUSION

These results provide first time evidence for pAkt and pmTOR in CD34+/K15+ KSCs localized to the outer root sheath niche of the bulge region of mouse hair follicles. Taken together, the present observations suggest that pAkt and pmTOR may allow this cell population to evade terminal differentiation and to persist for long periods of time in their specific niche. Strategies that target pAkt and pmTOR may deplete both cells within the CD34+/K]5+ KSCs compartment, as well as impacting the survival of nonproliferating suprabasal cells within pre-malignant papillomas.

Sanguinarine activates polycyclic aromatic hydrocarbon associated metabolic pathways in human oral keratinocytes and tissues

Sanguinarine's use in human clinical applications is currently controversial. While some studies have demonstrated sanguinarine's anti-inflammatory and anti-oxidant properties, other investigations reported sanguinarine's procarcinogenic effects. Like the tobacco-associated carcinogen, benzo(a)pyrene (B(a)P), sanguinarine is a polycyclic aromatic hydrocarbon (PAH). PAH exposure activates the aryl hydrocarbon transcription activating factor (AhR), resulting in nuclear translocation, binding to the aryl hydrocarbon nuclear translocator (ARNT), which thereby increases expression of a pool of carcinogen metabolizing enzymes. The goal of this study was to investigate whether sanguinarine activates this PAH-associated signaling cascade in human oral cells and tissues. Our results demonstrate that sanguinarine: (i) results in formation of the AhR-ARNT complex, (ii) induces AhR-associated gene expression, (iii) inhibits cytochrome P450 1A1 (CYP 1A1) microsomal oxidative activity and (iv) pretreatment upregulates CYP 1A1 function. Collectively, these data provide evidence that sanguinarine activates PAH-associated signaling and metabolic pathways. Notably, previous studies have demonstrated that mammalian hepatic microsomes metabolize sanguinarine to a mutagenic epoxide. Persons who respond to sanguinarine exposure with induction of primarily Phase I relative to Phase II enzymes are, therefore, at risk for sanguinarine bioactivation and its potential mutagenic effects.

Activated Akt-1 in specific cell populations during multi-stage skin carcinogenesis

The goal of the present study was to identify specific populations of cells that contain activated Akt-1, as determined by the presence ofphosphorylated Akt at serine 473 (p Akt), during development of skin tumors using a murine multi-stage carcinogenesis model. Nucleated papillomas cells as well as both epidermal and follicular keratinocytes in hyperplastic skin contained increased pAkt compared to skin treated only with acetone or 7, 12 dimethylbenz[a]anthracene (DMBA). Although the numbers of both mast cells and neutrophils were significantly increased in the stroma of papillomas (p<0.0005; p<0.0001, respectively), only mast cells contained pAkt. The amount of total Akt protein was similar regardless of time or treatment group examined. The present results suggest that activation of Akt-1 may provide specific populations of epidermal keratinocytes that develop into skin tumors with the ability to resist terminal differentiation and have enhanced proliferation during multi-stage skin carcinogenesis. In addition, mast cells which contain activated Akt-1 may persist within the stroma of papillomas during skin tumor development and progression through this signaling pathway, thereby contributing to a pro-oxidant and proangiogenic microenvironment.

Implications for oxidative and nitrative stress in the pathogenesis of AIDS-related Kaposi's sarcoma

AIDS-related Kaposi's sarcoma (AIDS-KS), which is the most prevalent AIDS related cancer, arises in a unique environment characterized by profound immunosuppression in conjunction with sustained immunostimulation. Persistent inflammation and the accompanying increased production of reactive species can promote carcinogenesis by numerous routes including sustained cell proliferation, initiation of nuclear and mitochondrial DNA mutations and induction of a proangiogenic environment. Furthermore, during conditions of continuous inflammation, protein nitration can result in irreversible inactivation of enzymes including the cytoprotective and reactive species degrading enzyme, mitochondrial superoxide dismutase (MnSOD). Because MnSOD serves as a putative tumor suppressor gene in addition to its reactive species inactivating capacities, the loss of MnSOD's cytoprotective functions could markedly facilitate malignant transformation. The purpose of this study was to investigate biochemical and molecular pathways by which reactive species facilitate AIDS-KS pathogenesis. Immunohistochemical studies of AIDS-KS tumors showed intense AIDS-KS lesional cell staining for MnSOD, inducible nitric oxide synthase (NOS 2) and the presence of a cellular 'fingerprint' of nitrative stress, 3-nitrotyrosine. Collectively, these results that imply reactive species stress occurs in situ. Similarly, cultured AIDS-KS cells derived from the AIDS-KS tumors contained both MnSOD protein and the 'high output' isoform, NOS 2. Co-localization studies established that the mitochondria are a primary site for 3-nitrotyrosine localization and immunoprecipitation/immunoblotting experiments confirmed that MnSOD tyrosine nitration occurs in AIDS-KS cells. Functional SOD assays showed that AIDS-KS cells possess significantly lower MnSOD activity relative to matched control cells; findings which correspond with ongoing MnSOD tyrosine nitration and subsequent inactivation within AIDS-KS cells. These results, which show in situ evidence of reactive species stress within AIDS-KS tumors and functional deficits attributable to nitrative stress in tumor-derived AIDS-KS lesional cells, imply that reactive species are intimately associated with AIDS-KS pathogenesis and provide insights for development of novel strategies for AIDS-KS clinical treatments.

AIDS-related Kaposi's sarcoma cells rapidly internalize endostatin, which co-localizes to tropomysin microfilaments and inhibits cytokine-mediated migration and invasion

AIDS-related Kaposi's sarcoma (KS) is the most common HIV-related malignancy. In some respects, KS is analogous to other angioproliferative diseases, in that KS lesions are highly vascularized and promoted by inflammatory cytokines. However, unlike other cancers or inflammatory mediated vascular diseases, KS is unique in that the KS lesional cells both express and respond to the complete angiogenic cytokines vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). Therefore, the angiogenic phenotype, which is crucial for cancer progression, is inherent to KS tumor cells. Due to the recognized importance of angiogenesis in cancer progression, numerous angiostatic agents are being investigated as potential therapeutic agents. One such agent is endostatin, which is a 20-kDa carboxyl-terminal fragment of collagen XVIII that has demonstrated potent angiostatic activities at both the in vivo and in vitro levels. Since endostatin is recognized as a potent angiostatic agent, the majority of in vitro endostatin studies have evaluated its effects on endothelial cells. Although KS cells are speculated to arise from endothelial cell precursors and KS lesions are highly vascularized, no previous studies have investigated endostatin-KS cell interactions. This present study evaluated endostatin's effects on KS tumor cell: (i) signal transduction (endostatin internalization and transcription factor activation), and (ii) migration and invasion (functional activity assays and tropomysin co-localization). Our results show that KS cells rapidly internalize endostatin and that endostatin initiates activation of the transcription activating factors nuclear factor-kappaB (NF-kappaB) and activating protein 1 (AP-1). Our data also show that internalized endostatin co-localizes to tropomysin microfilaments and acts to inhibit KS cell migration and invasion in response to the clinically relevant angiogenic cytokines VEGF and bFGF. As a consequence of its combined angiostatic and antitumorigenic activities, endostatin could provide dual therapeutic benefits for patients with mucocutaneous KS.

Endostatin inhibits migration and invasion of head and neck squamous cell carcinoma cells

Head and neck cancers are significant due to their high morbidity and associated complications. We report, for the first time, that endostatin directly affects epithelial lineage human cells derived from tumors of patients with head and neck squamous cell carcinoma (HNSCC). This study investigated endostatin's effects on several HNSCC cellular functions that are essential for tumor progression. We determined that exposure of HNSCC cells to endostatin activated the transcription-activating factors, NF-xB and AP-1 in a cell-line-dependent fashion. Endostatin also down-regulated the gene expression of several pro-migratory molecules. Migration and invasion assays showed that endostatin significantly inhibited these functions that are essential for tumor progression. Fluorescent labeling studies showed endostatin co-localized to tropomysin-binding HNSCC the microfilaments, suggesting endostatin's suppression of HNSCC cell migration and invasion may reflect perturbation of the microfilament function. Our data imply that endostatin's clinical efficacy extends beyond angiostatic properties to encompass a direct anti-tumorigenic effect against HNSCC cells.

Differential use of cardiac troponin T versus I in hemodialysis patients

BACKGROUND

Cardiac troponin T (cTnT) is frequently elevated in asymptomatic hemodialysis (HD) patients and predicts increased cardiovascular morbidity and mortality. Compared to cTnT, cardiac troponin I (cTnI) has a shorter half-life. How this influences its diagnostic reliability in chronic HD patients is only partially known.

PATIENTS AND METHODS

First, in a cross-sectional study cardiac troponins were measured in 31 asymptomatic HD patients. A third-generation cTnT assay was used. The rate of false positive tests and the intraindividual variability were determined. Second, in a retrospective analysis over 12 months all acute events with clinical suspicion for acute coronary syndrome (ACS) were analysed in the same patients to determine the diagnostic power of cTnT by receiver-operating curve (ROC) plot.

RESULTS

Cross-sectional study: 9 of 52 (17%) cTnT and 0/52 cTnI (0%) tests were positive in asymptomatic HD patients with a low intraindividual variability. Retrospective analysis: 16 acute clinical events with determination of cTnT were recorded, and in 4/16 an ACS was diagnosed. Using a cut-off level of 0.1 microg/l, the cTnT test reached a sensitivity of 100%, a specificity of 42%, a positive predicitive value of 36% and a negative predictive value of 100%, using a cut-off level of 0.2 microg/l the corresponding values were 75%, 58%, 38% and 88%.

CONCLUSIONS

Cardiac TnT, but only rarely cTnI, is elevated in a significant number of asymptomatic HD patients. For diagnosis of ACS in HD patients, a combination of cTnT and cTnI may be used, since the former has higher sensitivity and the latter higher specificity. A higher threshold value for cTnT in HD patients could further increase its diagnostic accuracy.

Curcumin activates the aryl hydrocarbon receptor yet significantly inhibits (-)-benzo(a)pyrene-7R-trans-7,8-dihydrodiol bioactivation in oral squamous cell carcinoma cells and oral mucosa

The development of oral squamous cell carcinoma (SCC) shows a positive correlation with the carcinogen exposure that occurs during tobacco and alcohol use. The purpose of this study was to investigate whether the naturally occurring chemopreventive agent, curcumin, modulates expression and function of carcinogen- metabolizing enzymes in human keratinocytes isolated from oral SCC tumors. Dose-response studies demonstrated that curcumin concentrations of >or=25 micro M were cytotoxic for oral SCC cells. Curcumin increased both expression (reverse transcription-PCR analyses) and function (high-performance liquid chromatography determination of ethoxyresorufin metabolism) of cytochrome P-450 (CYP) 1A1 and/or CYP1B1. The aryl hydrocarbon receptor (AhR), which up-regulates a battery of genes associated with carcinogen metabolism, is activated by polycyclic aromatic hydrocarbons such as the tobacco-associated carcinogen benzo(a)pyrene. Electromobility shift assays demonstrated that similar to the established AhR ligand 2,3,7,8,-tetrachlorodibenzo-p-dioxin, curcumin inclusion resulted in AhR nuclear translocation and formation of the transcriptionally active AhR-aryl hydrocarbon receptor nuclear translocator complex. Cellular capacity to bioactivate the tobacco-associated carcinogen (-)-benzo(a)pyrene-7R-trans-7,8-dihydrodiodiol was determined by evaluating conversion of the carcinogenic metabolite diol epoxide to stable tetrols via high-performance liquid chromatography. Results of our metabolism studies showed that curcumin significantly inhibited CYP1A1-mediated benzo(a)pyrene diol bioactivation in both oral SCC cells and intact oral mucosa. Because CYP1A1 is one of the primary carcinogen-activating enzymes in oral mucosa, the use of curcumin as an oral cavity chemopreventive agent could have significant clinical impact via its ability to inhibit carcinogen bioactivation.

Effects of 10-hydroxycamptothecin, delivered from locally injectable poly(lactide-co-glycolide) microspheres, in a murine human oral squamous cell carcinoma regression model

This study investigated whether local delivery of 10-hydroxycamptothecin provides effective inductive chemotherapy as assessed by significant tumor reduction. Established tumorigenic human oral squamous cell carcinoma cells were used for these experiments. The experimental groups were comprised of: control (blank (no drug) poly(lactide-co-glycolide) (PLGA) microspheres), intraperitoneal 10-hydroxycamptothecin delivery + blank microspheres, local bolus 10-hydroxycamptothecin + blank microspheres, and PLGA controlled-release microspheres. The 10-hydroxycamptothecin dose administered was 12 mg/kg (bolus-intraperitoneal, local) or controlled-release over 10 days. Regardless of delivery route, 10-hydroxycamptothecin significantly reduces tumor volume. However, PLGA microspheres provide significantly higher intratumor-drug concentrations (approximately 10 and 100 fold higher) relative to local bolus and intraperitoneal routes, respectively. Also, only the PLGA microspheres significantly reduced tumor weights. Camptothecin clinical applications are limited by drug inactivation at physiological pH and the need for sustained infusions. However, due to their acidic, camptothecin-stabilizing microclimate, PLGA microspheres could provide a novel delivery system for camptothecin-based induction chemotherapy.

Controlled-release of doxorubicin from poly(lactide-co-glycolide) microspheres significantly enhances cytotoxicity against cultured AIDS-related Kaposi's sarcoma cells

Subsequent to the introduction of highly active antiretroviral therapy (HAART), there has been a reduction in HIV viral titers and a concomitant decrease in AIDS-related Kaposi's sarcoma. However, as failure rates of HAART approach 30%, concerns arise regarding resurgence in AIDS-KS. Current AIDS-KS therapies fail to provide sustained remissions and yet also result in significant morbidity. Although partially effective, systemic chemotherapy is particularly debilitating to AIDS patients. In this report, we examined the co-incubation of AIDS-KS cells with doxorubicin which was slowly delivered from biodegradable, locally injectable, controlled-release poly(lactide-co-glycolide) (PLGA) microspheres. Local drug delivery systems such as PLGA microspheres can sustain therapeutic intralesional concentrations while minimizing deleterious systemic side effects, providing a pharmacologic advantage at the treatment site. Our data show that controlled release from PLGA microspheres augments doxorubicin cytotoxicity towards AIDS-KS cells without increasing toxicity in nonlesional cells from the AIDS-KS donors. Electron microscopic analysis revealed that PLGA microspheres possess a strong affinity for cell membranes, facilitating doxorubicin delivery to redox-sensitive cell membrane sites. Consistent with their speculated endothelial cell lineage, some of the AIDS-KS cells appeared to engulf microspheres via phagocytosis. Our results suggest that PLGA controlled-release doxorubicin microspheres have potential clinical applicability in management of AIDS-KS.

Sustained angiogenesis enables in vivo transplantation of mucocutaneous derived AIDS-related Kaposi's sarcoma cells in murine hosts

AIDS-related Kaposi's sarcoma (AIDS-KS), the most prevalent HIV-associated malignancy, is a debilitating, potentially fatal disease. Currently, there is a need for development of AIDS-KS therapies that are not only well tolerated, but also capable of providing sustained remission. Preclinical assessment of pharmacological parameters and therapeutic efficacies are dependent upon in vivo parameters. However, there are currently no animal KS models and mucocutaneous KS cell isolates have proved to be non-tumorigenic in animal hosts. This report describes the development of a murine model that enables in vivo transplantation of 'native' low population doubling level AIDS-KS cells from biopsy-confirmed mucocutaneous lesions. The angiogenic phenotype of in situ AIDS-KS lesions is reconstituted via controlled release of a complete angiogenic peptide, recombinant human basic fibroblast growth factor (bFGF), from locally injectable, biodegradable polylactide-co-glycolide implants. Consequential to the sustained local release of bioactive bFGF, a murine vascular network is established, which facilitates the in vivo transplantation of AIDS-KS cells. Desirable aspects of this model include: low cost murine species, transplantation of non-selected patient cells and use of animal hosts that are T cell-deficient. The transplanted human AIDS-KS cells and extensive murine vascular network create lesions that retain a striking resemblance, at both the gross and microscopic levels, to in situ AIDS-KS tumors. Because the bFGF-induced murine vascular network is analogous to the abundant vascularity present in AIDS-KS lesions, this murine model should provide an excellent vehicle for numerous clinically relevant studies, such as assessment of drug clearance at AIDS-KS lesional sites. Finally, applicability of this method is not restricted to AIDS-related malignancies. Establishment and maintenance of an extensive host vascular network should augment success rates for in vivo transplantation of numerous other human cell strains or lines.

[Water births and the exposure to HIV]

The risk of a work related HIV-exposure or infection to midwives, or other HCW, in attending waterbirths of (possible unrecognized) HIV-positive women is unknown. Our goal was the quantification of the loss of blood of the childbearing woman after a waterbirth into the waterpool, in taking pool-water-samples of 14 different waterbirths and measuring the hemoglobin in the plasma, and then correlating the mean found loss of blood and the mean quantity of poolwater with a hypothetical HIV-RNA viral load of 10(3)-10(6) copies per milliliters (ml) blood. All attended waterbirths were evaluated with a questionnaire regarding: parity of the child-bearing woman; serostatus for HIV/Hepatitis-B (HBV) and Hepatitis-C (HCV); length of the birth-process; perineum-rupture or not, etc. Questions concerning the HCW in implementing universal precautions like: type of gloves and garment used, if at all; duration of water contact with the hands; existing skin lesions; HBV-vaccination-status; years of professional experiences as a midwife; how many waterbirths attended etc. were also evaluated. The mean calculated loss of blood into the pool was 300 ml, the mean pool-water content 633 liters. With a hypothetical (maximal) HIV-RNA viral load of 10(6) copies per ml blood, we calculated a mean HIV-RNA viral load of 476 copies per ml pool-water. We also found 37% of the interviewed midwives (n = 14) to have skin lesions on hands or fingers; 1 received splashes into her (unprotected) face and 1 was not immunized against HBV. The mean loss of blood of 300 ml into the pool is a relevant amount. The skin-contact of the HCW with the potentially contaminated water is the norm, because of the failure of the type of used gloves. Because of the diluting effect of the poolwater, we estimate the potential risk for a HIV-exposure to intact skin as minimal and, therefore a potential HIV-infection as "low level" and to be unlikely. However, a risk for nosocomial HBV-infection is significantly higher. We recommend wearing long-sleeved gloves, waterproofed garment, and HBV-vaccination to all HCW.