Optimization of decalcification techniques for histologic examination of the rat maxillary and mandibular incisors for toxicity studies.

The objective of this study was to provide optimized processing for examination of rat incisors in nonclinical toxicity studies that enables analysis using immunohistochemistry (IHC). Rat maxillas and mandibles were decalcified in Immunocal, a formic acid decalcifier, and Decal Stat, a hydrochloric acid decalcifier, to evaluate tissue quality when with hematoxylin and eosin (H&E) stain and an IHC. Following necropsy of 10 to 13-week-old male Sprague Dawley rats, tissues were collected, trimmed, fixed in neutral buffered formalin (NBF), and placed into the corresponding decalcifying solution.

Selective inhibition of the BD2 bromodomain of BET proteins in prostate cancer.

Proteins of the bromodomain and extra-terminal (BET) domain family are epigenetic readers that bind acetylated histones through their bromodomains to regulate gene transcription. Dual-bromodomain BET inhibitors (DbBi) that bind with similar affinities to the first (BD1) and second (BD2) bromodomains of BRD2, BRD3, BRD4 and BRDt have displayed modest clinical activity in monotherapy cancer trials. A reduced number of thrombocytes in the blood (thrombocytopenia) as well as symptoms of gastrointestinal toxicity are dose-limiting adverse events for some types of DbBi.

Oncostatin M promotes STAT3 activation, VEGF production, and invasion in osteosarcoma cell lines.

Background: We have previously demonstrated that both canine and human OSA cell lines, as well as 8 fresh canine OSA tumor samples, exhibit constitutive phosphorylation of STAT3, and that this correlates with enhanced expression of matrix metalloproteinase-2 (MMP2). While multiple signal transduction pathways can result in phosphorylation of STAT3, stimulation of the cytokine receptor gp130 through either IL-6 or Oncostatin M (OSM) is the most common mechanism through which STAT3 is activated. The purpose of this study was to evaluate the role of IL-6 and OSM stimulation on both canine and human OSA cell lines to begin to determine the role of these cytokines in the biology of OSA.

The novel curcumin analog FLLL32 decreases STAT3 DNA binding activity and expression, and induces apoptosis in osteosarcoma cell lines.

Background: Curcumin is a naturally occurring phenolic compound shown to have a wide variety of antitumor activities; however, it does not attain sufficient blood levels to do so when ingested. Using structure-based design, a novel compound, FLLL32, was generated from curcumin. FLLL32 possesses superior biochemical properties and more specifically targets STAT3, a transcription factor important in tumor cell survival, proliferation, metastasis, and chemotherapy resistance.

The small molecule curcumin analog FLLL32 induces apoptosis in melanoma cells via STAT3 inhibition and retains the cellular response to cytokines with anti-tumor activity.

Background: We characterized the biologic effects of a novel small molecule STAT3 pathway inhibitor that is derived from the natural product curcumin. We hypothesized this lead compound would specifically inhibit the STAT3 signaling pathway to induce apoptosis in melanoma cells.

Results: FLLL32 specifically reduced STAT3 phosphorylation at Tyr705 (pSTAT3) and induced apoptosis at micromolar amounts in human melanoma cell lines and primary melanoma cultures as determined by annexin V/propidium iodide staining and immunoblot analysis.

Cutaneous wound reepithelialization is compromised in mice lacking functional Slug (Snai2).

Background: Keratinocytes at wound margins undergo partial epithelial to mesenchymal transition (EMT). Based on previous in vitro and ex vivo findings, Slug (Snai2), a transcriptional regulator of EMT in development, may play an important role in this process.

Objectives: This study was designed to validate an in vivo role for Slug in wound healing.

The novel HSP90 inhibitor STA-1474 exhibits biologic activity against osteosarcoma cell lines.

Osteosarcoma (OSA), the most common malignant bone tumor in dogs and children, exhibits a similar clinical presentation and molecular biology in both species. Unfortunately, 30-40% of children and 90% of dogs still die of disease despite aggressive therapy. The purpose of this study was to test the biologic activity of a novel heat shock protein 90 (HSP90) inhibitor, STA-1474, against OSA.

Characterization of STAT3 activation and expression in canine and human osteosarcoma.

Background: Dysregulation of signal transducer and activator of transcription 3 (STAT3) has been implicated as a key participant in tumor cell survival, proliferation, and metastasis and is often correlated with a more malignant tumor phenotype. STAT3 phosphorylation has been demonstrated in a subset of human osteosarcoma (OSA) tissues and cell lines. OSA in the canine population is known to exhibit a similar clinical behavior and molecular biology when compared to its human counterpart, and is often used as a model for preclinical testing of novel therapeutics.

Snai2 expression enhances ultraviolet radiation-induced skin carcinogenesis.

Snai2, encoded by the SNAI2 gene, has been shown to modulate epithelial-mesenchymal transformation (EMT), the conversion of sessile epithelial cells attached to adjacent cells and to the basement membrane into dissociated and motile fibroblastic cells. EMT occurs during development, wound healing, and carcinoma progression. Using Snai2-null mice (Snai2(lacZ)), we evaluated the role of Snai2 in UV radiation (UVR)-induced skin carcinogenesis.