Amplification of the Angiogenic Signal through the Activation of the TSC/mTOR/HIF Axis by the KSHV vGPCR in Kaposi's Sarcoma

Background: Kaposi’s sarcoma (KS) is a vascular neoplasm characterized by the dysregulated expression of angiogenic and inflammatory cytokines. The driving force of the KS lesion, the KSHV-infected spindle cell, secretes elevated levels of vascular endothelial growth factor (VEGF), essential for KS development. However, the origin of VEGF in this tumor remains unclear. Methodology/Principal Findings: Here we report that the KSHV G protein-coupled receptor (vGPCR) upregulates VEGF in KS through an intricate paracrine mechanism. The cytokines secreted by the few vGPCR-expressing tumor cells activate in neighboring cells multiple pathways (including AKT, ERK, p38 and IKK$\beta$) that, in turn, converge on TSC1/2, promoting mTOR activation, HIF upregulation, and VEGF secretion. Conditioned media from vGPCR-expressing cells lead to an mTORdependent increase in HIF-1$\alpha$ and HIF-2$\alpha$ protein levels and VEGF upregulation. In a mouse allograft model for KS, specific inhibition of the paracrine activation of mTOR in non-vGPCR-expressing cells was sufficient to inhibit HIF upregulation in these cells, and abolished the ability of the vGPCR-expressing cells to promote tumor formation $in$ $vivo$. Similarly, pharmacologic inhibition of HIF in this model blocked VEGF secretion and also lead to tumor regression. Conclusions/Significance: Our findings provide a compelling explanation for how the few tumor cells expressing vGPCR can contribute to the dramatic amplification of VEGF secretion in KS, and further provide a molecular mechanism for how cytokine dysregulation in KS fuels angiogenesis and tumor development. These data further suggest that activation of HIF by vGPCR may be a vulnerable target for the treatment of patients with KS

Expression and alterations of the PTEN/AKT/mTOR pathway in ameloblastomas

Objectives: Recently, an allelic loss of phosphatase and tensin homologue (PTEN) was shown to occur in ameloblastomas. In carcinogenesis, loss of PTEN allows for overactivity of the phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathway inducing an upregulation of mammalian-target of rapamycin (mTOR) and its downstream effector ribosomal-subunit-6 kinase (S6K); allowing for uncontrolled cell proliferation, apoptosis inhibition and cell cycle deregulation. Methods: Thirty ameloblastomas and five dental follicles were studied, looking at the immunohistochemical expression of total PTEN and AKT, as well as their phosphorylated (p) active forms, and the downstream effector and indicator of mTOR activity p70 ribosomal-subunit-6 kinase (pS6K). Also assessed was the expression of extracellular-signal-regulated kinase (ERK), which cross talks with AKT. Results: Total PTEN was absent in 33.3% of ameloblastomas, while its stabilized, phosphorylatedser380/thr382/thr383 form was absent in 83.3% of tumors. In contrast, AKT was expressed in 83.3% of ameloblastomas, showing high expression of the p-thr308AKT and p-ser473 AKT forms in 93.3% and 56.6% of cases, respectively. Further, the mTOR activated pS6Kser240/244 was detected in 86.7% of ameloblastomas, while ERK was overexpressed in 70.0% of the cases. Conclusion: Immunohistochemical analysis of aberrant signaling in the PI3K/AKT/mTOR pathway in ameloblastomas may represent a valuable tool for elucidating pathogenesis, aggressiveness and selecting optimal therapeutics. © 2007 The Authors

Sialolipoma of the lower lip: Case report and literature review

Sialolipoma is a relatively rare and fairly recently described as a variant of lipoma with salivary elements. Any site within the oral and maxillofacial region may be involved with the parotid gland being the most common location. Herein, we present a case of silaolipoma in lower lip. The clinical and histological features and differential diagnosis are discussed. © Binmadi et al.; Licensee Bentham Open

Sulindac induces apoptosis and inhibits tumor growth in vivo in head and neck squamous cell carcinoma

Sulindac has antineoplastic effects on various cancer cell lines; consequently, we assessed sulindac's effects on laryngeal squamous cell carcinoma (SCC) cells in vitro and in vivo. In vitro, SCC (HEP-2) cells treated with various cyclooxygenase inhibitors or transfected with constitutively active signal transducer and activator of transcription 3 (Stat3) or survivin vectors were analyzed using Western blot analysis, annexin V assay, and cell proliferation assay. In parallel, nude mice injected subcutaneously with HEP-2 cells were either treated intraperitoneally with sulindac or left untreated, and analyzed for tumor weight, survivin expression, and tyrosine-phosphorylated Stat3 expression. In vitro studies confirmed the selective antiproliferative and proapoptotic effects of sulindac, which also downregulated Stat3 and survivin protein expression. Stat3 or survivin forced expression partially rescued the antiproliferative effects of sulindac. In vivo studies showed significant repression of HEP-2 xenograft growth in sulindactreated mice versus controls, with near-complete resolution at 10 days. Additionally, tumor specimens treated with sulindac showed downregulation of phosphorylated tyrosine-705 Stat3 and survivin expression. Taken together, our data suggest, for the first time, a specific inhibitory effect of sulindac on tumor growth and survivin expression in laryngeal cancer, both in vitro and in vivo, in a Stat3-dependent manner, suggesting a novel therapeutic approach to head and neck cancer. Copyright © 2007 Neoplasia Press, Inc. All rights reserved

Assessment of TLR4 and TLR9 signaling and correlation with human papillomavirus status and histopathologic parameters in oral tongue squamous cell carcinoma

Objectives: Toll-like receptors (TLRs) may promote or inhibit tumor progression. The aim of this study was to assess the expression of TLR4 and TLR9 and their downstream targets in oral tongue squamous cell carcinoma (OTSCC) in correlation with histopathologic parameters and human papillomavirus (HPV) status. Study Design: OTSCC (fully or superficially invasive and in situ) were studied. Immunohistochemical expression of TLR4, TLR9, nuclear factor-κΒ (NF-κΒ/p65), and interferon-β (IFN-β) was evaluated in tumor and inflammatory cells and in adjacent morphologically normal mucosa. HPV status was also determined. Results: TLR4 showed increased expression levels in tumor and infiltrating inflammatory cells compared with adjacent mucosa, especially in fully invasive cases; a negative correlation between TLR4 levels in inflammatory cells and tumor grade was observed. TLR9 was upregulated in tumor and infiltrating inflammatory cells compared with the adjacent mucosa; its expression in inflammatory cells was higher in well differentiated tumors. NF-κΒ and IFN-β were elevated in cancerous tissues, especially in fully invasive cases, and positively correlated with TLR4 and/or TLR9. HPV positivity (detected in 15.9% of the cases) demonstrated positive correlation with TLR9 and NF-κΒ levels. Conclusions: TLR4 and TLR9 are upregulated in OTSCC and its microenvironment and, by affecting important downstream molecules, such as NF-κB and IFN-β, may play a role in oral cancer development and progression. © 2020 Elsevier Inc

Juvenile trabecular ossifying fibroma: Immunohistochemical expression of MDM2, CDK4 and p53 compared to conventional ossifying fibroma

Background: Juvenile ossifying fibroma (JOF) is an uncommon benign fibro-osseous lesion of the craniofacial skeleton; compared to conventional ossifying fibroma (OF), JOF is characterized by local aggressiveness and propensity for recurrence. The biologic basis for this different biologic behavior between JOF and OF remains elusive. The aim of this study was to evaluate the immunohistochemical expression of MDM2, CDK4 and p53, molecules associated with bone oncogenesis, in the trabecular variant of JOF. Material and Methods: The study material consisted of five cases of trabecular JOF, affecting three male and two female patients with a mean age of 11.8 years. Three cases arose in the maxilla and two in the mandible. All cases were initially treated by enucleation; two cases recurred necessitating more aggressive treatment. Immunohistochemical study of MDM2, CDK4 and p53 was performed in all cases, as well as in five control cases of conventional OF. Results: CDK4 positivity was noted in all JOF cases; the staining pattern was diffuse and strong in 4 cases and focal and weak in one case. In contrast, 4 out of 5 cases of OF were weakly and focally CDK4 positive, the remaining one being negative. Immunostaining for MDM2 was observed in 3 JOF cases; all OF were MDM2 negative. All cases of OF and JOF were negative for p53, except for one focally positive JOF case. Conclusions: CDK4 and MDM2 expression in the trabecular variant of JOF is higher compared to conventional OF. In contrast, p53 expression is almost universally negative in JOF and OF. Despite some overlapping features, differential expression patterns of proteins involved in bone oncogenesis can elucidate the pathogenesis and may facilitate accurate diagnosis and prediction of behavior of bone tumors in the craniofacial region. © 2022. Journal of Clinical and Experimental Dentistry. All Rights Reserved

Secretory leukocyte protease inhibitor (SLPI) expression and tumor invasion in oral squamous cell carcinoma

Differential expression of secretory leukocyte protease inhibitor (SLPI) impacts on tumor progression. SLPI directly inhibits elastase and other serine proteases, and regulates matrix metalloproteinases, plasminogen activation, and plasmin downstream targets to influence invasion. We examined tissues from human oral squamous cell carcinoma (OSCC) for SLPI expression in parallel with proteases associated with tumor progression and evaluated their relationships using tumor cell lines. Significantly decreased SLPI was detected in OSCC compared to normal oral epithelium. Furthermore, an inverse correlation between SLPI and histological parameters associated with tumor progression, including stage of invasion, pattern of invasion, invasive cell grade, and composite histological tumor score was evident. Conversely, elevated plasmin and elastase were positively correlated with histological parameters of tumor invasion. In addition to its known inhibition of elastase, we identify SLPI as a novel inhibitor of plasminogen activation through its interaction with annexin A2 with concomitant reduced plasmin generation by macrophages and OSCC cell lines. In an in vitro assay measuring invasive activity, SLPI blocked protease-dependent tumor cell migration. Our data suggest that SLPI may possess antitumorigenic activity by virtue of its ability to interfere with multiple requisite proteolytic steps underlying tumor cell invasion and may provide insight into potential stratification of oral cancer according to risk of occult metastasis, guiding treatment strategies. Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved