Joshua R. Bradish

Mice lacking epidermal PPARγ exhibit a marked augmentation in photocarcinogenesis associated with increased UVB‐induced apoptosis, inflammation and barrier dysfunction

Recent studies suggest that peroxisome proliferator‐activated receptor gamma (PPARγ) agonists may have cancer chemopreventive activity. Other studies have shown that loss of epidermal PPARγ results in enhanced chemical carcinogenesis in mice via unknown mechanisms. However, ultraviolet B (UVB) exposure represents the primary etiological agent for skin cancer formation and the role of PPARγ in photobiology and photocarcinogenesis is unknown. In previous studies, we demonstrated that UVB irradiation of cells results in the formation of oxidized glycerophosphocholines that exhibit PPARγ ligand activity. We therefore hypothesized that PPARγ would prove to be a chemopreventive target in photocarcinogenesis. We first showed that UVB irradiation of mouse skin causes generation of PPARγ agonist species in vivo. We then generated SKH‐1 hairless, albino mice deficient in epidermal Pparg (Pparg−/−epi) using a cytokeratin 14 driven Cre‐LoxP strategy. Using a chronic model of UVB photocarcinogenesis, we next showed that Pparg−/−epi mice exhibit an earlier onset of tumor formation, increased tumor burden and tumor progression. Increased tumor burden in Pparg−/−epi mice was accompanied by a significant increase in epidermal hyperplasia and p53 positive epidermal cells in surrounding skin lacking tumors. After acute UVB irradiation, Pparg−/−epi mice exhibited an augmentation of both UVB‐induced Caspase 3/7 activity and inflammation. Increased apoptosis and inflammation was also observed after treatment with the PPARγ antagonist GW9662. With chronic UVB irradiation, Pparg−/−epi mice exhibited a sustained increase in erythema and transepidermal water loss relative to wildtype littermates. This suggests that PPARγ agonists could have possible chemopreventive activity in non‐melanoma skin cancer.

Spatiotemporal Assessments of Dermal Hyperemia Enable Accurate Prediction of Experimental Cutaneous Carcinogenesis as well as Chemopreventive Activity

Field cancerization refers to areas of grossly normal epithelium that exhibit increased risk for tumor occurrence. Unfortunately, elucidation of the locoregional changes that contribute to increased tumor risk is difficult due to the inability to visualize the field. In this study, we use a noninvasive optical-based imaging approach to detail spatiotemporal changes in subclinical hyperemia that occur during experimental cutaneous carcinogenesis. After acute inflammation from 10 weeks of UVB irradiation subsides, small areas of focal hyperemia form and were seen to persist and expand long after cessation of UVB irradiation. We show that these persistent early hyperemic foci reliably predict sites of angiogenesis and overlying tumor formation. More than 96% of the tumors (57 of 59) that developed following UVB or 7,12-dimethylbenz(a)anthracene/phorbol 12-myristate 13-acetate (DMBA/PMA) treatment developed in sites of preexisting hyperemic foci. Hyperemic foci were multifocal and heterogeneously distributed and represented a minor fraction of the carcinogen-treated skin surface (10.3% of the imaging area in vehicle-treated animals). Finally, we also assessed the ability of the anti-inflammatory agent, celecoxib, to suppress hyperemia formation during photocarcinogenesis. The chemopreventive activity of celecoxib was shown to correlate with its ability to reduce the area of skin that exhibit these hyperemic foci, reducing the area of imaged skin containing hyperemic foci by 49.1%. Thus, we propose that a hyperemic switch can be exploited to visualize the cancerization field very early in the course of cutaneous carcinogenesis and provides insight into the chemopreventive activity of the anti-inflammatory agent celecoxib.

Towards personalized therapy for patients with malignant melanoma: molecular insights into the biology of BRAF mutations

BRAF mutations have been identified as the most common oncogene mutation in melanomas, especially important in those originating on nonchronically sun-damaged skin. There is a large and continually growing body of evidence regarding the importance of this mutation in targeted therapy for melanoma. In this review, we outline these findings including: molecular pathways used by BRAF, the importance in nonmalignant neoplasms, histologic associations, the relationship of BRAF to KIT and NRAS mutations, and their impact on survival, as well as resistance mechanisms to BRAF inhibitors employed by melanoma. Understanding these topics and how they relate to one another may facilitate the development of new treatments and eventually improve the prognosis for those patients afflicted with this disease.

STAT6-Mediated Keratitis and Blepharitis: A Novel Murine Model of Ocular Atopic Dermatitis

PURPOSE Atopic dermatitis (AD) is a common inflammatory disease that can affect the eye, resulting in ocular pathologies, including blepharitis, keratitis, and uveitis; however, the pathogenic mechanisms underlying the ocular manifestations of AD are not well understood. METHODS In the present study, we characterized the ocular pathologies that develop in the Stat6VT mouse model of AD. We examined the cytokine profile of the eyelid lesions, measured the behavioral response, and documented the treatment response to topical steroids. RESULTS Our results show that Stat6VT mice spontaneously developed blepharitis, keratitis, and uveitis similar to that observed in patients with AD. Histologic findings of allergic inflammation in affected eyelids in this model include the presence of a lymphocyte-predominant infiltrate and tissue eosinophilia in the dermis. Gene expression analysis of affected eyelid tissue by quantitative PCR revealed increased amounts of mRNAs for the Th2 cytokines IL-4, IL-5, and IL-13. In addition, increased eyelid scratching was seen in Stat6VT mice with blepharitis. Topical treatment with the corticosteroid clobetasol reduced eyelid inflammation, tissue eosinophilia, and Th2 cytokine expression. CONCLUSIONS The development of AD-like ocular pathologies in this model supports the idea that in humans, AD-associated disease of the eye may be driven by Th2-mediated inflammation and demonstrates that the Stat6VT mouse may be a useful system in which to further investigate pathogenesis of and treatment strategies for blepharitis and other ocular diseases that develop in association with AD.

Topical Application of a Platelet Activating Factor Receptor Agonist Suppresses Phorbol Ester-Induced Acute and Chronic Inflammation and Has Cancer Chemopreventive Activity in Mouse Skin

Platelet activating factor (PAF) has long been associated with acute edema and inflammatory responses. PAF acts by binding to a specific G-protein coupled receptor (PAF-R, Ptafr). However, the role of chronic PAF-R activation on sustained inflammatory responses has been largely ignored. We recently demonstrated that mice lacking the PAF-R (Ptafr-/- mice) exhibit increased cutaneous tumorigenesis in response to a two-stage chemical carcinogenesis protocol. Ptafr-/- mice also exhibited increased chronic inflammation in response to phorbol ester application. In this present study, we demonstrate that topical application of the non-hydrolysable PAF mimetic (carbamoyl-PAF (CPAF)), exerts a potent, dose-dependent, and short-lived edema response in WT mice, but not Ptafr -/- mice or mice deficient in c-Kit (c-Kit W-sh/W-sh mice). Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications. Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis. The ability of CPAF to suppress acute and chronic inflammatory changes in response to PMA application(s) was PAF-R dependent, as CPAF had no effect on basal or PMA-induced inflammation in Ptafr-/- mice. Moreover, c-Kit appears to be necessary for the anti-inflammatory effects of CPAF, as CPAF had no observable effect in c-Kit W-sh/W-sh mice. These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development.

Carney syndrome in a patient previously considered to have Peutz-Jeghers syndrome.

To the Editor: We report a case of Carney syndrome in an 18-year-old male patient who presented with a previous diagnosis of Peutz-Jeghers syndrome and a rapidly growing asymptomatic tumor of his right upper lip, present for the past 7 months. Since age 6 years, this patient has had multiple lentigines of his face and oral mucosa. Approximately 3 years before coming to our attention, he had bilaterally enlarged testicles and a right orchiectomy that revealed a large cell calcifying Sertoli cell tumor. A review of systems also revealed occasional bloody stools. At that time, the patient was incorrectly diagnosed with PeutzJeghers syndrome and gastrointestinal surveillance was initiated. Endoscopy revealed a single 5-mm sessile polyp on the duodenal bulb that was not biopsied. Colonoscopy was unremarkable. Additional studies, including thyroid and endoscopic ultrasound as well as genetic evaluation, were not performed. His family history was negative for mucocutaneous lesions, gastrointestinal polyps, or myxomas. When the patient presented at this institution, physical examination revealed a single, 7-cm, firm, nontender tumor involving the right upper lip with 2 flesh-colored, 0.5-cm papules overlying the surface. There were also multiple dark pigmented macules involving the face, lips, and oral mucosa. The tumor was biopsied and revealed a myxoid spindle cell proliferation with mild to moderate cellularity. The patient underwent reconstructive surgery for complete excision. Gross examination revealed a 73 3.83 3.3-cm tumor. Microscopic examination demonstrated a hypercellular spindle cell proliferation with rich vascular network of thin-walled vessels, numerous neutrophils, and myxoid background that infiltrated adjacent connective tissue (Fig 1). Immunohistochemical staining was positive for vimentin and CD34 and negative for S100, AE1/ AE3, factor XIIIa, and actin. The lesion was called a superficial angiomyxoma, the patient was correctly diagnosed with Carney syndrome, and proper follow-up was initiated. This case highlights the importance of following strict diagnostic criteria as well as understanding the pathology behind the diagnostic criteria of PeutzJeghers andCarney syndrome (Table I). The incorrect diagnosis of Peutz-Jeghers was made prematurely because diagnostic criteria had not yet been met. This prompted inappropriate follow-up (gastrointestinal surveillance) looking for intestinal polyps. Peutz-Jeghers associated polyps are a disorganized growth of normal tissue (hamartomatous) with a smooth muscle core that is unique to Peutz-Jeghers polyps and not seen in patients with Carney syndrome. Regardless of whether these polyps carry malignant potential, obtaining a biopsy helps fulfill diagnostic criteria when the diagnosis is still in question. Both syndromes share mucocutaneous lentigines as a feature but only Carney syndrome is associated with superficial angiomyxomas. It is important to recognize when these occur, because there is a higher risk of cardiac myxomas that can obstruct blood flow and cause heart failure. Physicians should rule out Carney syndrome and Peutz-Jeghers syndrome when a patient presents with features common to both. Finding one additional feature unique to either improves diagnostic certainty and guides the physician toward a proper follow-up and surveillance strategy. Recommended follow-up can help detect precursor lesions and other complications before they become life threatening.