Active Stat3 is required for survival of human squamous cell carcinoma cells in serum-free conditions

BACKGROUND: Squamous cell carcinoma (SCC) of the skin is the most aggressive form of non-melanoma skin cancer (NMSC), and is the single most commonly diagnosed cancer in the U.S., with over one million new cases reported each year. Recent studies have revealed an oncogenic role of activated signal transducer and activator of transcription 3 (Stat3) in many human tumors, especially in those of epithelial origin, including skin SCC. Stat3 is a mediator of numerous growth factor and cytokine signaling pathways, all of which activate it through phosphorylation of tyrosine 705. RESULTS: To further address the role of Stat3 in skin SCC tumorigenesis, we have analyzed a panel of human skin-derived cell lines ranging from normal human epidermal keratinocytes (NHEK), to non-tumorigenic transformed skin cells (HaCaT), to highly tumorigenic cells (SRB1-m7 and SRB12-p9) and observed a positive correlation between Stat3 phosphorylation and SCC malignancy. We next determined the role of Stat3 activity in cell proliferation and viability under serum-free culture conditions. This was accomplished by suppressing Stat3 activity in the SRB12-p9 cells through stable expression of a dominant negative acting form of Stat3β, which contains a tyrosine 705 to phenylalanine mutation (S3DN). The S3DN cells behaved similar to parental SRB12-p9 cells when cultured in optimal growth conditions, in the presence of 10% fetal calf serum. However, unlike the SRB12-p9 cells, S3DN cells underwent apoptotic cell death when cultured in serum-free medium (SFM). This was evidenced by multiple criteria, including accumulation of sub-G1 particles, induced PARP cleavage, and acquisition of the characteristic morphological changes associated with apoptosis. CONCLUSION: This study provides direct evidence for a role for Stat3 in maintaining cell survival in the conditions of exogenous growth factor deprivation produced by culture in SFM. We also propose that delivery of the S3DN gene or protein to tumor cells could induce apoptosis and/or sensitize those cells to the apoptotic effects of cancer therapeutic agents, raising the possibility of using S3DN as an adjunct for treatment of skin SCC

Highly Pathogenic Avian Influenza A(H5N1) Virus Outbreak in New England Seals, United States

We report the spillover of highly pathogenic avian influenza A(H5N1) into marine mammals in the northeastern United States, coincident with H5N1 in sympatric wild birds. Our data indicate monitoring both wild coastal birds and marine mammals will be critical to determine pandemic potential of influenza A viruses

Coumarins are competitive inhibitors of cytochrome P450 1B1, with equal potency for allelic variants

Objectives Coumarins are naturally occurring chemicals with potential as chemopreventive agents, several with known action on the cytochrome P450 1A family. We examined whether cytochrome P450 1B1 (CYP1B1) was inhibited by coumarins, whether such inhibition was competitive, and whether inhibition varied between common polymorphic variants of this enzyme. Methods We tested the inhibition properties of four coumarins, bergamottin, isopimpinellin, isoimperatorin, and imperatorin in an assay for oxidation of (-)benzo[a]pyrene-7R-trans-7,8-dihyrodiol (B[a]P-7,8-diol) by CYP1B1 using yeast-microsome expressed enzymes. These assays were performed with wild-type enzyme and five single-amino acid polymorphic variants. Results All four coumarins are competitive inhibitors of CYP1B1, with Ki values equal to 587, 11, 6 and 1 μM respectively. Inhibition parameters were consistent between five haplotypes of CYP1B1, three representing common haplotypes in Asians, African-Americans and European-Americans, and two with baseline kinetic parameters previously shown to be potentially different from wild-type. Conclusions Coumarins are capable of inhibiting carcinogen activation by CYP1B1 with varying potencies, and their efficacy as chemopreventive agents is not likely to be affected by polymorphism in this enzyme. © 2005 Lippincott Williams & Wilkins

Active Stat3 is required for survival of human squamous cell carcinoma cells in serum-free conditions

Abstract Background Squamous cell carcinoma (SCC) of the skin is the most aggressive form of non-melanoma skin cancer (NMSC), and is the single most commonly diagnosed cancer in the U.S., with over one million new cases reported each year. Recent studies have revealed an oncogenic role of activated signal transducer and activator of transcription 3 (Stat3) in many human tumors, especially in those of epithelial origin, including skin SCC. Stat3 is a mediator of numerous growth factor and cytokine signaling pathways, all of which activate it through phosphorylation of tyrosine 705. Results To further address the role of Stat3 in skin SCC tumorigenesis, we have analyzed a panel of human skin-derived cell lines ranging from normal human epidermal keratinocytes (NHEK), to non-tumorigenic transformed skin cells (HaCaT), to highly tumorigenic cells (SRB1-m7 and SRB12-p9) and observed a positive correlation between Stat3 phosphorylation and SCC malignancy. We next determined the role of Stat3 activity in cell proliferation and viability under serum-free culture conditions. This was accomplished by suppressing Stat3 activity in the SRB12-p9 cells through stable expression of a dominant negative acting form of Stat3β, which contains a tyrosine 705 to phenylalanine mutation (S3DN). The S3DN cells behaved similar to parental SRB12-p9 cells when cultured in optimal growth conditions, in the presence of 10% fetal calf serum. However, unlike the SRB12-p9 cells, S3DN cells underwent apoptotic cell death when cultured in serum-free medium (SFM). This was evidenced by multiple criteria, including accumulation of sub-G1 particles, induced PARP cleavage, and acquisition of the characteristic morphological changes associated with apoptosis. Conclusion This study provides direct evidence for a role for Stat3 in maintaining cell survival in the conditions of exogenous growth factor deprivation produced by culture in SFM. We also propose that delivery of the S3DN gene or protein to tumor cells could induce apoptosis and/or sensitize those cells to the apoptotic effects of cancer therapeutic agents, raising the possibility of using S3DN as an adjunct for treatment of skin SCC.</p

Concurrent dual allergen exposure and its effects on airway hyperresponsiveness, inflammation and remodeling in mice

Experimental mouse models of asthma have broadened our understanding of the mechanisms behind allergen-induced asthma. Typically, mouse models of allergic asthma explore responses to a single allergen; however, patients with asthma are frequently exposed to, and tend to be allergic to, more than one allergen. The aim of the current study was to develop a new and more relevant mouse model of asthma by measuring the functional, inflammatory and structural consequences of chronic exposure to a combination of two different allergens, ovalbumin (OVA) and house dust mite (HDM), in comparison with either allergen alone. BALB/c mice were sensitized and exposed to OVA, HDM or the combination of HDM and OVA for a period of 10 weeks. Following allergen exposure, airway responsiveness was measured using the flexiVent small animal ventilator, and mice were assessed for indices of airway inflammation and remodeling at both 24 hours and 4 weeks after the final allergen exposure. Mice exposed to the HDM-OVA combination exhibited increased numbers of inflammatory cells in the bronchoalveolar lavage (BAL) when compared with mice exposed to a single allergen. Mice exposed to HDM-OVA also exhibited an elevated level of lung tissue mast cells compared with mice exposed to a single allergen. Following the resolution of inflammatory events, mice exposed to the allergen combination displayed an elevation in the maximal degree of total respiratory resistance (Max RRS) compared with mice exposed to a single allergen. Furthermore, trends for increases in indices of airway remodeling were observed in mice exposed to the allergen combination compared with a single allergen. Although concurrent exposure to HDM and OVA resulted in increased aspects of airway hyperresponsiveness, airway inflammation and airway remodeling when compared with exposure to each allergen alone, concurrent exposure did not result in a substantially more robust mouse model of allergic asthma than exposure to either allergen alone

“A great way to start the conversation”: Evidence for the Use of an Adolescent Mental Health Chatbot Navigator for Youth at Risk of HIV and other STIs

Chatbot use is increasing for mobile health interventions on sensitive and stigmatized topics like mental health because of their anonymity and privacy. This anonymity provides acceptability to sexual and gendered minority youth (ages 16-24) at increased risk of HIV and other STIs with poor mental health due to higher levels of stigma, discrimination, and social isolation. This study evaluates the usability of Tabatha-YYC, a pilot chatbot navigator created to link these youth to mental health resources. Tabatha-YYC was developed using a Youth Advisory Board (n=7), and the final design underwent user testing (n=20) through a think-aloud protocol, semi-structured interview, and a brief survey post-exposure which included the Health Information Technology Usability Evaluation Scale. The chatbot was found to be an acceptable mental health navigator by participants. This study provides important design methodology considerations and key insights into chatbot design preferences of youth at risk of STIs seeking mental health resources.  </p