Study of feline oral squamous cell carcinoma: potential target for cyclooxygenase inhibitor treatment

2024 ISFM and AAFP consensus guidelines on the long-term use of NSAIDs in cats

PRACTICAL RELEVANCE

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used and are effective for the management of pain in cats. These Guidelines will support veterinarians in decision-making around prescribing NSAIDs in situations of chronic pain, to minimise adverse effects and optimise pain management. Information is provided on mechanism of action, indications for use, screening prior to prescription, use in the presence of comorbidities, monitoring of efficacy, and avoidance and management of adverse effects.

CLINICAL CHALLENGES

The cat's unique metabolism should be considered when prescribing any medications, including NSAIDs. Chronic pain may be challenging to detect in this species and comorbidities, particularly chronic kidney disease, are common in senior cats. Management of chronic pain may be complicated by prescription of other drugs with the potential for interactions with NSAIDs.

EVIDENCE BASE

These Guidelines have been created by a panel of experts brought together by the International Society of Feline Medicine (ISFM) and American Association of Feline Practitioners (AAFP). Information is based on the available literature, expert opinion and the panel members' experience.

Feline SCCs of the Head and Neck Display Partial Epithelial-Mesenchymal Transition and Harbor Stem Cell-like Cancer Cells

Squamous cell carcinoma of the head and neck (HNSCC) is a malignant cancer disease in humans and animals. There is ample evidence that the high plasticity of cancer cells, i.e., their ability to switch from an epithelial to a mesenchymal, endothelial, and stem cell-like phenotype, chiefly contributes to progression, metastasis, and multidrug resistance of human HNSCCs. In feline HNSCC, the field of cancer cell plasticity is still unexplored. In this study, fourteen feline HNSCCs with a known feline papillomavirus (FPV) infection status were subjected to histopathological grading and subsequent screening for expression of epithelial, mesenchymal, and stem cell markers by immunohistochemistry (IHC) and immunofluorescence staining (IF). Irrespective of the FPV infection status, all tumors except one corresponded to high-grade, invasive lesions and concurrently expressed epithelial (keratins, E-cadherin, β-catenin) and mesenchymal (vimentin, N-cadherin, CD146) proteins. This finding is indicative for partial epithelial-mesenchymal transition (pEMT) events in the lesions, as similarly described for human HNSCCs. IF double staining revealed the presence of CD44/CD271 double-positive cells notably within the tumors' invasive fronts that likely correspond to cancer stem cells. Taken together, the obtained findings suggest that feline HNSCCs closely resemble their human counterparts with respect to tumor cell plasticity.

Effects of selective cyclooxygenase-2 inhibitor robenacoxib on primary cells derived from feline injection-site sarcoma

Feline injection-site sarcomas (FISSs) are highly invasive malignant mesenchymal neoplasms that arise from injection sites in cats. Although the tumorigenesis of FISSs is still uncertain, there is a consensus that FISS is associated with chronic inflammation caused by irritation of injection-related trauma and foreign chemical substances. Chronic inflammation can provide a proper microenvironment for tumour development, which has been known as one of the risk factors of tumorigenesis in many tumours. To investigate the tumorigenesis of FISS and screen for its potential therapeutic targets, cyclooxygenase-2 (COX-2), an inflammation-enhancing enzyme, was selected as a target for this study. In vitro experiments using FISS- and normal tissue-derived primary cells and robenacoxib, a highly selective COX-2 inhibitor, were performed. The results demonstrated that expression of COX-2 could be detected in formalin-fixed and paraffin-embedded FISS tissues and FISS-derived primary cells. Cell viability, migration and colony formation of FISS-derived primary cells were inhibited, and cell apoptosis was enhanced by robenacoxib in a dose-dependent manner. However, susceptibility to robenacoxib varied in different lines of FISS primary cells and was not completely correlated with COX-2 expression. Our results suggest that COX-2 inhibitors could be potential adjuvant therapeutics against FISSs.

Low dose meloxicam is safe and tolerable when combined with toceranib phosphate in cancer-bearing cats

OBJECTIVES

Non-steroidal anti-inflammatory drugs (NSAIDs) are infrequently utilized in cats due to concern for renal compromise; however, recent studies demonstrate tolerability of low dose meloxicam. Toceranib phosphate is used to treat several feline cancers and is well tolerated. This study aimed to determine the tolerability and adverse event profile of combined toceranib and low dose meloxicam in cancer-bearing cats. Secondary goals involved assessing anticancer tumor efficacy and impact upon quality of life and analgesia.

METHODS

Cats with any cancer not involving the kidneys were eligible. The study adopted a conventional 3 + 3 dose escalation design. Toceranib was administered every other day at a standard dose with meloxicam administered in an escalating fashion in subsequent cohorts, at a starting dose of 0.01 mg/kg on opposite days to toceranib, up to a maximum of 0.02 mg/kg daily, based upon previous safety studies. Laboratory work, blood pressure, tumor measurements, pain score and client-completed quality-of-life surveys were recorded every 2-4 weeks during the 12-week study period.

RESULTS

Twenty-one cats were enrolled. When combined with toceranib, a meloxicam dose of 0.02 mg/kg q24h was safe and well tolerated, with no cats being withdrawn due to adverse events from the drug combination. The majority of cats demonstrated clinical benefit with stable to mildly improved tumor measurements, quality of life and pain scores.

CONCLUSIONS AND RELEVANCE

Low dose meloxicam combined with toceranib is safe and well tolerated in cancer-bearing cats. Continued patient recruitment and data collection are needed to determine the maximum tolerated dose of meloxicam. The results of our study will guide further phase II/III trials.

Companion Animal Model in Translational Oncology; Feline Oral Squamous Cell Carcinoma and Canine Oral Melanoma

Simple Summary

Laboratory rodents are the most common animal models used in preclinical cancer research. Companion animals with naturally occurring cancers are an under-utilized natural model for the development of new anti-cancer drugs. Dogs and cats develop several types of cancers that resemble those arising in humans with similar clinical and histopathological features and often with similar molecular and genetic backgrounds. Exposure to environmental carcinogens, including air, food and water are also common between people and their pets. Dogs and cats are a unique model that could be integrated between the preclinical laboratory animal model and human clinical trials.

Abstract

Companion animals with naturally occurring cancers can provide an advantageous model for cancer research and in particular anticancer drug development. Compared to commonly utilized mouse models, companion animals, specifically dogs and cats, share a closer phylogenetical distance, body size, and genome organization. Most importantly, pets develop spontaneous, rather than artificially induced, cancers. The incidence of cancer in people and companion animals is quite similar and cancer is the leading cause of death in dogs over 10 years of age. Many cancer types in dogs and cats have similar pathological, molecular, and clinical features to their human counterparts. Drug toxicity and response to anti-cancer treatment in dogs and cats are also similar to those in people. Companion animals share their lives with their owners, including the environmental and socioeconomic cancer-risk factors. In contrast to humans, pets have a shorter life span and cancer progression is often more rapid. Clinical trials in companion animals are cheaper and less time consuming compared to human trials. Dogs and cats with naturally occurring cancers are an ideal and unique model for human cancer research. Model selection for the specific type of cancer is of pivotal importance. Although companion animal models for translational research have been reviewed previously, this review will try to summarize the most important advantages and disadvantages of this model. Feline oral squamous cell carcinoma as a model for head and neck squamous cell carcinoma and canine oral melanoma as a model for mucosal melanoma and immunotherapy in people will be discussed as examples.

Intersecting Mechanisms of Hypoxia and Prostaglandin E2-Mediated Inflammation in the Comparative Biology of Oral Squamous Cell Carcinoma

The importance of inflammation in the pathogenesis of cancer was first proposed by Rudolph Virchow over 150 years ago, and our understanding of its significance has grown over decades of biomedical research. The arachidonic acid pathway of inflammation, including cyclooxygenase (COX) enzymes, PGE2 synthase enzymes, prostaglandin E2 (PGE2) and PGE2 receptors has been extensively studied and has been associated with different diseases and different types of cancers, including oral squamous cell carcinoma (OSCC). In addition to inflammation in the tumour microenvironment, low oxygen levels (hypoxia) within tumours have also been shown to contribute to tumour progression. Understandably, most of our OSCC knowledge comes from study of this aggressive cancer in human patients and in experimental rodent models. However, domestic animals develop OSCC spontaneously and this is an important, and difficult to treat, form of cancer in veterinary medicine. The primary goal of this review article is to explore the available evidence regarding interaction between hypoxia and the arachidonic acid pathway of inflammation during malignant behaviour of OSCC. Overlapping mechanisms in hypoxia and inflammation can contribute to tumour growth, angiogenesis, and, importantly, resistance to therapy. The benefits and controversies of anti-inflammatory and anti-angiogenic therapies for human and animal OSCC patients will be discussed, including conventional pharmaceutical agents as well as natural products.

Squamous cell carcinoma of the anal sac in two cats

This report describes two cases of feline anal sac squamous cell carcinoma. Cat 1 was managed with a multimodal approach combining surgical resection, radiation therapy and systemic therapy (toceranib phosphate; Palladia™) until local recurrence was identified at 236 days postsurgery. At that time, the cat received carboplatin. With the tumour being progressive, the cat was euthanased 552 days post initial surgery. Cat 2 was managed palliatively with a non-steroidal anti-inflammatory (meloxicam) and supportive medications. Unfortunately, with further decline in quality of life following initial diagnosis, the cat was euthanased 28 days later. Squamous cell carcinoma should be considered as a possible differential diagnosis when a cat is presented for investigation of an anal sac mass.

Cyclooxygenase-2 as a Biomarker with Diagnostic, Therapeutic, Prognostic, and Predictive Relevance in Small Animal Oncology

In canine and feline populations, the number of neoplasm cases continues to increase around the world. Attempts are being made in centres of research to identify new biomarkers that speed up and improve the quality of oncological diagnostics and therapy in human and animal tumour patients. Cyclooxygenase-2 (COX-2) is a promising biomarker with increasing relevance to human oncology, but as yet with less application in veterinary oncology. The expression of COX-2 increases significantly during pathological processes involving inflammation, pain or fever. It is also overexpressed in humans presenting various types of tumours and in selected types of tumours in animals, particularly in dogs. This article discusses the expression of COX-2 in canine and feline tumours, the importance of COX-2 as a biomarker with diagnostic, therapeutic, prognostic and predictive relevance in oncology, and the clinical significance of inhibiting COX-2 overexpression in tumours.

CD147 and Cyclooxygenase Expression in Feline Oral Squamous Cell Carcinoma

Feline oral squamous cell carcinoma (OSCC) is a highly invasive form of cancer in cats. In human OSCC, cluster of differentiation 147 (CD147) contributes to inflammation and tumor invasiveness. CD147 is a potential therapeutic target, but the expression of CD147 in feline OSCC has not been examined. Immunohistochemistry was used to determine if cyclooxygenase 2 (COX-2) and CD147 expression in feline OSCC biopsies was coordinated. Tumor cells were more likely to express COX-2 (22/43 cases or 51%) compared to stroma (8/43 or 19%) and adjacent oral epithelium (9/31 cases or 29%) (p < 0.05). CD147 was also more likely to occur in tumor cells compared to stroma and adjacent mucosa, with 21/43 (49%) of cases having >50% tumor cells with mild or moderate CD147 expression, compared to 9/28 (32%) in adjacent epithelium and only 5/43 (12%) in adjacent stroma (p < 0.05). In feline OSCC cell lines (SCCF1, SCCF2, and SCCF3), CD147 gene expression was more consistently expressed compared to COX-2, which was 60-fold higher in SCCF2 cells compared to SCCF1 cells (p < 0.05). CD147 expression did not correlate with COX-2 expression and prostaglandin E2 (PGE2) secretion, indicating that they may be independently regulated. CD147 potentially represents a novel therapeutic target for the treatment of feline OSCC and further study of CD147 is warranted.

Probable cutaneous adverse drug reaction to piroxicam in a cat

Case summary

A 9-year-old male neutered Devon Rex cat presented with bilaterally symmetrical ulcerative lesions with mucopurulent exudate that developed rapidly. The lesions were apparent on the axillae, ventral abdomen and inguinal areas. The cat was systemically well. Piroxicam was being administered for palliative treatment of a previously diagnosed salivary adenocarcinoma. Histopathology revealed severe extensive epidermal ulceration with focal dyskeratotic keratinocytes in the stratum granulosum without lymphocyte satellitosis. Resolution of skin lesions was observed after discontinuing piroxicam. Similar lesions developed after previous piroxicam administration, further suggesting a possible adverse reaction to this drug. In addition, the Naranjo score indicated that piroxicam was a probable cause for the ulcerative skin lesions.

Relevance and novel information

This is the first report of piroxicam, a non-steroidal anti-inflammatory drug, as a probable cause of ulcerative skin lesions in a cat.

Investigation of immune cell markers in feline oral squamous cell carcinoma

Squamous cell carcinoma is the most common oral cancer in the cat and presents as a locally aggressive lesion for which an effective therapeutic protocol remains elusive. Feline oral squamous cell carcinoma (OSCC) shares many clinical characteristics with human head and neck squamous cell carcinoma (HNSCC). Accordingly, present studies were conducted to determine similarities for immune markers shared by feline OSCC and human HNSCC. Biopsies harvested from a feline patient cohort-1 (n = 12) were analyzed for lymphoid cell infiltrates by immunohistochemistry (IHC). Results revealed unique patterns of T cell infiltration involving both neoplastic epithelium and stroma that were detected in most patient tumor biopsies (92%) examined by IHC staining for CD3. Intratumoral B cell infiltrates were detected within tumor stroma only, based on IHC staining for CD79a and CD20 for all patients within the same cohort-1. Infiltration of tumors by a regulatory CD4 T cell subset (Tregs) defined by expression of the forkhead transcription factor FoxP3, was also detected in biopsies from 57% of patients and involved infiltration of neoplastic epithelium and stroma. Patient biopsies were also examined for expression of immunomodulator cyclooxygenase (COX)-2 and revealed positive but weak staining of neoplastic epithelium in a significant proportion of cases (75%). Interestingly, COX-2 expression was detected in both neoplastic epithelium and stroma. Blood collected from a second cohort of feline OSCC patients (n = 9) revealed an increased frequency of circulating CD4+FoxP3+ T cells when compared to healthy adult controls (n = 7) (P = 0.045), although frequencies of CD4+CD25+FoxP3+ T cells were comparable between patients and healthy pet cat controls. Lastly, biopsies from feline OSCC patients were characterized for histologic subtype using a classification scheme previously described for human HNSCC. This analysis revealed the conventional subtype as the predominant variant (75%) with conventional subtypes split evenly between well differentiated and moderately differentiated carcinomas. Two cases were classified as papillary and one case as basaloid subtypes. Correlations between subtype, immune marker scores or circulating Treg frequencies and clinical characteristics or outcome were not detected, most likely due to small patient numbers within patient cohorts. However, findings from these studies provide a preliminary step in the characterization of immune and histologic markers that will be critical to defining prognostic immune markers for feline OSCC and potential targets for testing of immunotherapeutics also relevant to human HNSCC in future studies.

Inhibition of the PI3K/AKT Pathway Sensitizes Oral Squamous Cell Carcinoma Cells to Anthracycline-Based Chemotherapy In Vitro

Anthracycline-based chemotherapy, such as doxorubicin (Dox), while effective against many solid tumors, is not widely used for head and neck cancers. In this study, we evaluated the efficacy of Dox, and its derivative AD198 in human, canine, and feline oral squamous cell carcinomas cells (OSCC) in vitro. Dox and AD198 had significant an anti-proliferative effect on human, canine, and feline OSCC cells in dose-dependent manner. AD198 inhibited cell proliferation more effectively than Dox in tested OSCC cells. In the human oral squamous cell carcinoma SCC25 cells, Dox and AD198 increased the production of reactive oxygen species and subsequently increased apoptosis through activation of caspase signaling pathway. Dox and AD198 increased activation of AKT, ERK1/2, and p38 MAPK signaling pathways in tested OSCC cells by dose-dependent manner. The efficacy of Dox and AD198 treatments in inhibition of cell proliferation was increased in tested OSCC when combined with PI3K/AKT inhibitor, LY294002 treatment. Inhibition of PI3K/AKT reduced Dox- and AD198-induced activation of ERK1/2 and further increased Dox- and AD198-induced phosphorylation of p38 MAPK in OSCC. Our results suggest that the anthracycline therapies, such as Dox or AD198, can be more effective for treatment of OSCC when combined with inhibitors of the PI3K/AKT pathway. J. Cell. Biochem. 118: 2615-2624, 2017. © 2016 Wiley Periodicals, Inc.

Invasive tracheal neoplasia in eight cats: descriptive cases and review of the current literature

Case series summary

This case series describes eight cases of invasive tracheal neoplasia that were recognized between the years 1989 and 2014 from a single tertiary referral hospital. This is a disproportionately high number of cases compared with the total number of reports in the current literature.

Relevance and novel information

Invasive tracheal neoplasia is uncommonly diagnosed in domestic cats. Feline tracheal tumors mimic other upper respiratory diseases making diagnosis challenging. Prognosis is guarded to grave, with most cats surviving less than 1 month after beginning treatment. Severe respiratory distress in cats often warrants humane euthanasia. Appropriate clinical suspicion and awareness can expedite diagnoses leading to prolonged survival rates with appropriate treatments. This case series represents the largest number of feline tracheal tumors reported and also describes the first unique histological presentation of what the authors believe to be a poorly differentiated tracheal carcinoma.

Animal models of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the most common oral cancer worldwide. Local bone invasion into the maxilla or mandible and metastasis to regional lymph nodes often result in a poor prognosis, decreased quality of life and shortened survival time for HNSCC patients. Poor response to treatment and clinical outcomes are the major concerns in this aggressive cancer. Multiple animal models have been developed to replicate spontaneous HNSCC and investigate genetic alterations and novel therapeutic targets. This review provides an overview of HNSCC as well as the traditional animal models used in HNSCC preclinical research. The value and challenges of each in vivo model are discussed. Similarity between HNSCC in humans and cats and the possibility of using spontaneous feline oral squamous cell carcinoma (FOSCC) as a model for HNSCC in translational research are highlighted.

Feline Oral Squamous Cell Carcinoma: Clinical Manifestations and Literature Review

Squamous cell carcinoma (SCC) is the most commonly encountered malignant oral tumor in cats. The etiology of this locally invasive tumor is likely multifactorial. Several risk factors have been identified, including the use of flea collars, and a history of feeding canned food and canned tuna. Clinical signs vary depending on tumor location. The tumor commonly arises from the gingiva and mucosa of the maxilla, mandible, tongue, sublingual area, or tonsillar region. Maxillary SCC commonly presents clinically as an ulcerative lesion, whereas mandibular SCC is commonly proliferative, expansile, and firm. Lingual/sublingual SCC may be ulcerative, necrotic, infiltrative, or proliferative. In general, feline oral SCC is an invasive and malignant neoplasm regardless of its location. Surgery, radiation therapy, chemotherapy and combinations thereof have been attempted with rarely a satisfactory response. Currently, cures are obtained only in a small subset of cats whose tumors are amenable to complete resection, or where resection with microscopic residual disease is followed by definitive radiation therapy. A multimodal treatment approach likely offers the best chance of success. For cats with advanced disease, palliative care may improve patients' quality of life, albeit transiently. Sequelae associated with tumor progression and local tissue destruction often result in euthanasia of feline patients with oral SCC.

Piroxicam inhibits Masitinib-induced cyclooxygenase 2 expression in oral squamous cell carcinoma cells in vitro

Development and characterization of animal models for human cancers is important for the improvement of diagnosis and therapy. The oral squamous cell carcinoma (OSCC) of domestic animals resembles human OSCC in many aspects; thus, cell lines derived from OSCC of cats and dogs are a valuable model for human OSCC. We characterized 1 feline OSCC (FeOSCC-Sidney) and 1 canine OSCC (K9OSCC-Abby) cell line and compared their characteristics with human OSCC cell line hSCC-25. We calculated the doubling time of the new OSCC cell lines and evaluated the expression profiles of cancer-related markers and cell-cycle proteins such as c-kit, platelet-derived growth factor receptor, vascular endothelial growth factor receptor, epidermal growth factor receptor, cyclooxygenase (COX)-1, COX-2, and p27 by immunocytochemistry and Western blot analysis. We evaluated the effects of novel receptor tyrosine kinase inhibitor (Masitinib, AB1010) and the nonsteroidal anti-inflammatory drug piroxicam on the previously mentioned OSCC cells. Interestingly, AB1010 increased expression levels of COX-2 in all tested OSCCs. Cotreatment of piroxicam with Masitinib significantly inhibited cell proliferation of OSCC as compared to either drug alone through the c-kit and AKT signaling pathways. Piroxicam inhibited Masitinib-induced COX-2 expression in all tested OSCCs. Therefore, targeting these two signaling pathways simultaneously was more efficient for inhibition of OSCCs across these species.

Evaluation of the clinical use of tepoxalin and meloxicam in cats

Medical records where tepoxalin (Zubrin) or meloxicam (Metacam) were prescribed in cats were reviewed and data extracted. Comparisons were performed for exploring changes between pre- and post-non-steroidal anti-inflammatory drug course laboratory tests. Seventy-nine medical records fit the inclusion criteria (n = 57 and n = 22, tepoxalin and meloxicam, respectively). The median dosages administered were 13 and 0.029 mg/kg(/)day (tepoxalin and meloxicam, respectively). Median prescription durations were 11 (2-919) and 93 (4-1814) days for tepoxalin and meloxicam, respectively. Suspected adverse events were reported for tepoxalin (9%, 5/57 cats) and meloxicam (18%, 4/22 cats) a median of 774 and 448 days, respectively, after the prescription started. For cats prescribed meloxicam, there were several statistically significant changes for serum biochemistry and hematology parameters, but median values were within normal limits. These valuable clinical data suggest that tepoxalin and meloxicam are well tolerated in the clinical setting at the doses prescribed in this study.

A naturally occurring feline model of head and neck squamous cell carcinoma

Despite advances in understanding cancer at the molecular level, timely and effective translation to clinical application of novel therapeutics in human cancer patients is lacking. Cancer drug failure is often a result of toxicity or inefficacy not predicted by preclinical models, emphasizing the need for alternative animal tumor models with improved biologic relevancy. Companion animals (dogs and cats) provide an opportunity to capitalize on an underutilized and biologically relevant translational research model which allows spontaneous disease modeling of human cancer. Head and neck squamous cell carcinoma (HNSCC) is a common cancer with a poor prognosis and limited clinical advancements in recent years. One potential novel spontaneous animal tumor model is feline oral squamous cell carcinoma (FOSCC). FOSCC and HNSCC share similar etiopathogenesis (tobacco and papillomavirus exposure) and molecular markers (EGFR, VEGF, and p53). Both human and feline SCCs share similar tumor biology, clinical outcome, treatment, and prognosis. Future clinical trials utilizing FOSCC as a tumor model may facilitate translation of preclinical cancer research for human cancer patients.

Evaluation of hypoxia in a feline model of head and neck cancer using ⁶⁴Cu-ATSM positron emission tomography/computed tomography

Background

Human and feline head and neck squamous cell carcinoma (HNSCC) share histology, certain molecular features, as well as locally aggressive and highly recurrent clinical behavior. In human HNSCC, the presence of significant hypoxia within these tumors is considered an important factor in the development of a more aggressive phenotype and poor response to therapy. We hypothesized that feline head and neck tumors, particularly HNSCC, would exhibit hypoxia and that ⁶⁴Cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) positron emission tomography/computed tomography (PET/CT) would permit detection of intratumoral hypoxia.

Methods

12 cats with measureable head and neck tumors were given ⁶⁴Cu-ATSM and iodinated contrast for PET/CT scan. The presence or absence of hypoxia was also assessed using an intratumoral fluorescent life-time probe to quantitate pO₂ and pimonidazole immunohistochemical staining in biopsy specimens. In two cats, intratumoral O₂ and ⁶⁴Cu-ATSM uptake was measured before and after treatment with anti-angiogenic agents to determine the effect of these agents on hypoxia.

Results

Eleven of twelve feline tumors demonstrated significant ⁶⁴Cu-ATSM uptake, regardless of malignant or benign etiology. The presence (and absence) of hypoxia was confirmed using the fluorescent O₂ detection probe in nine tumors, and using pimonidazole staining in three tumors. Squamous cell carcinomas (HNSCC) demonstrated the highest degree of hypoxia, with T_max/M ratios ranging from 4.3 to 21.8. Additional non-neoplastic tissues exhibited ⁶⁴Cu-ATSM uptake suggestive of hypoxia including reactive draining lymph nodes, non-malignant thyroid pathology, a tooth root abscess, and otitis media. In two cats with HNSCC that received anti-vascular agents, the pattern of ⁶⁴Cu-ATSM uptake was altered after treatment, demonstrating the potential of the feline model to study the modulation of tumor oxygenation.

Conclusion

Feline HNSCC serves as a clinically relevant model for the investigation of intratumoral hypoxia including its measurement, modulation and targeting.

5-lipoxygenase expression and tepoxalin-induced cell death in squamous cell carcinomas in cats

OBJECTIVE

To assess expression pattern and subcellular compartmentalization of 5-lipoxygenase in cutaneous, UV radiation-induced, and oral squamous cell carcinomas (SCCs) in cats and determine the effects of cyclooxygenase or 5-lipoxygenase inhibition on proliferation or apoptosis in a feline oral squamous cell carcinoma (SCCF1) cell line.

SAMPLE

60 archived paraffin-embedded samples of SCCs from 60 cats and SCCF1 cells.

PROCEDURES

Retrospective immunohistochemical analysis of the archived samples of SCCs (20 cutaneous, 20 UV radiation-induced, and 20 oral tumors) was performed. Cell culture proliferation assays involving SCCF1 cells were performed, and tepoxalin-induced apoptosis and signaling were examined via western blotting and annexin V staining.

RESULTS

Immunohistochemically, staining for 5-lipoxygenase was most frequently of greatest intensity in oral SCCs, whereas staining of cutaneous and UV radiation-induced lesions had less consistent 5-lipoxygenase expression. Exposure of SCCF1 cells to the 5-lipoxygenase inhibitor tepoxalin resulted in apoptosis; the effect appeared to be mediated via alteration of cell signaling rather than via suppression of lipid mediators that are typically produced as a result of 5-lipoxygenase activity.

CONCLUSIONS AND CLINICAL RELEVANCE

In cats, expression of 5-lipoxygenase in SCCs appeared to differ depending on tumor location. The influence of tepoxalin-induced 5-lipoxygenase inhibition on a 5-lipoxygenase-expressing cell line coupled with the notable expression of 5-lipoxygenase in oral SCCs suggested that 5-lipoxygenase inhibition may have therapeutic benefits in affected cats. Although the safety of tepoxalin in cats has yet to be investigated, 5-lipoxygenase inhibitors should be evaluated for use as a potential treatment for SCCs in that species.

Lingual Lesions in the Dog and Cat: Recognition, Diagnosis, and Treatment

The tongue plays many vital roles in the oral cavity of the dog and cat. Consequently, lingual lesions can have devastating effects on an animal's overall health. This article provides a review of tongue anatomy as well as a review of the etiology, gross appearance, and diagnostic procedures indicated for a wide variety of lingual lesions. Lingual pathologic conditions that are reviewed include traumatic, metabolic, idiopathic, infectious, immune-mediated, hereditary, and neoplastic lesions. This article also describes current concepts in the medical management of lingual lesions.

Cyclooxygenase-2 expression in animal cancers

Cyclooxygenase (COX; also known as prostaglandin endoperoxide synthase) is a key enzyme in the biochemical pathway leading to the synthesis of prostaglandins. A large amount of epidemiological and experimental evidence supports a role for COX-2, the inducible form of the enzyme, in human tumorigenesis, notably in colorectal cancer. COX-2 mediates this role through the production of PGE(2) that acts to inhibit apoptosis, promote cell proliferation, stimulate angiogenesis, and decrease immunity. Similarly, COX-2 is believed to be involved in the oncogenesis of some cancers in domestic animals. Here, the author reviews the current knowledge on COX-2 expression and role in cancers of dogs, cats, and horses. Data indicate that COX-2 upregulation is present in many animal cancers, but there is presently not enough information to clearly define the prognostic significance of COX-2 expression. To date, only few reports document an association between COX-2 expression and survival, notably in canine mammary cancers and osteosarcomas. Some evidence suggests that COX inhibitors could be useful in the prevention and/or treatment of certain cancers in domestic animals, the best example being urinary transitional cell carcinomas in dogs. However, determination of the levels of COX-2 in a tumor does not appear to be a good prognostic factor or a good indicator for the response to nonsteroidal anti-inflammatory drug therapy. Clearly, additional research, including the development of in vitro cell systems, is needed to determine if COX-2 expression can be used as a reliable prognostic factor and as a definite therapeutic target in animal cancers.

ISFM and AAFP Consensus Guidelines: Long-Term use of NSAIDs in Cats

NSAIDs and cats Non-steroidal anti-inflammatory drugs (NSAIDs) are an important class of drug in feline medicine, having analgesic, anti-inflammatory and antipyretic activity. While most published data on their use in this species relate to short-term (often perioperative) therapy, there is increasing evidence of the value of these drugs in treating chronic pain in cats (for example, that associated with degenerative joint disease), and some NSAIDs have now become licensed for long-term use in cats in some geographies. Most of our knowledge of therapeutic mechanisms or adverse drug reactions associated with NSAIDs is extrapolated from work in other species, and there is a paucity of published data relating to cats.

Guidelines These guidelines have been drawn together by an expert panel, which have reviewed the current literature on long-term NSAID use in cats and other species, and developed guidance on their use based on this information. The aim is to provide practical information for veterinarians to encourage appropriate NSAID therapy whenever cats will benefit from the use of these drugs.

Primary esophageal squamous cell carcinoma in a cat

Primary esophageal squamous cell carcinoma causing stricture was diagnosed in a cat via endoscopy and computed tomography. Difficulty in making this diagnosis via endoscopic biopsy alone is described. Although balloon dilatation was unsuccessful, supportive care via gastrostomy tube feeding and administration of piroxicam successfully allowed a 16-week survival from the time of presentation and a 4-week survival from the onset of treatment with piroxicam.

Treatment choices for oral cancer in cats. What is possible? What is reasonable?

Practical relevance Oral cancers are not the most common tumour in our domestic cats, but the death rate associated with cancer in this location is particularly high. This is largely because the cancer is discovered late in its development and also because of the severe debility it causes when the patient is unable or unwilling to eat and drink.

Audience This review of malignant oral tumours (squamous cell carcinoma, oral sarcoma, oral melanoma and salivary adenocarcinoma) and benign oral tumours that may mimic malignant lesions is directed at all veterinarians that see older cats - both for ‘health and wellness’ as well as for more advanced treatment of already diagnosed neoplasia.

Patient group As it is almost always older cats that are affected, patients will have a strong bond with their owners. These cats also often have unrelated intercurrent disease that may affect treatment choices, the way treatment is administered, and whether the owner chooses aggressive or palliative therapy.

Evidence base While the literature on treatment of oral cancer in dogs is well established, until recently it was less so in cats. As researchers focus on treating cats with curative intent, as well as palliatively and supportively, the material available to guide veterinarians has also increased. This article evaluates the current literature from the author's perspective as an oncologist and a cat owner.

Molecular Characterization of Feline COX-2 and Expression in Feline Mammary Carcinomas

Cyclooxygenase-2 (COX-2), the rate-limiting enzyme in the biosynthesis of prostaglandins, plays an important role in inflammation and tumorigenesis. COX-2 primary structure has been characterized in many species and its expression demonstrated in a variety of cancers in humans and dogs, including mammary cancer. In contrast, there is currently little information on the structure of feline COX-2. Also, information on COX-2 expression in feline mammary cancer is limited and conflicting. The objectives of this study were therefore to characterize the molecular structure of feline COX-2 and to evaluate by immunohistochemistry its expression in mammary carcinomas. Our results show that the predicted coding region of feline COX-2 encodes a 604-amino acid protein, which is identical in length to several COX-2 homologs. Feline COX-2 amino acid sequence is highly similar to other mammalian COX-2 homologs. Immunohistochemical analysis of 40 mammary carcinomas showed that the majority of tumors studied (35/40; 87%) expressed COX-2 at a level varying from low (20/40; 50%) to intermediate (13/40; 32%) and high (2/40; 5%). These results provide the first molecular characterization of feline COX-2 and demonstrate that COX-2 is expressed in the majority of feline mammary carcinomas.