Effects of folate deficiency and sex on carcinogenesis in a mouse model of oral cancer.

OBJECTIVES: To investigate the effects of dietary folate and sex on histopathology of oral squamous cell carcinoma in mice. MATERIALS AND METHODS: Mice (C57Bl/6, 30/sex) were fed either a deficient folate or sufficient folate diet. Vehicle or 4-nitroquinoline1-oxide (50 µg/mL) in vehicle were administered in drinking water for 20 weeks, followed by 6 weeks of regular drinking water. Oral lesions were observed weekly. Tongues were studied for histopathologic changes. Immunohistochemical techniques were used to measure cell proliferation (Ki67+), and to quantify expression of folate receptor, reduced folate carrier, and proton-coupled folate transporter. T cells, macrophages, and neutrophils were counted and normalized to area. RESULTS: All 4NQO-treated mice developed oral tumors. Dietary folate level did not affect tumor burden. More tumors were observed on the ventral aspect of the tongue than in other locations within the oral cavity. 4-nitroquinoline-1-oxide-treated mice displayed 27%-46% significantly lower expression of all three folate transport proteins; diet and sex had no effect on folate transporter expression. T-cell and neutrophil infiltration in tongues were 9.1-fold and 18.1-fold increased in the 4-nitroquinoline-1-oxide-treated mouse tongues than in controls. CONCLUSION: Treatment with 4NQO was the primary factor in determining cancer development, decreased folate transport expression, and lymphoid cell infiltration.

Early detection of oral potentially malignant disorders using machine learning: a retrospective pilot study.

Early diagnosis of oral potentially malignant disorders (OPMDs) may be hindered by similar clinical presentations shared between benign oral lesions and OPMDs. The goal of this retrospective pilot study was to assess the use of machine learning (ML) as an adjunctive evaluation in conjunction with conventional comprehensive oral examination of OMPDs. Digital images of 80 deidentified intraoral lesions (40 benign intraoral lesions and 40 OPMDs) were collected. The images, which were previously identified independently by experienced oral pathologists, were used to create 3 datasets: raw images, grayscale images, and enhanced color images. The datasets were subsequently divided into training (n = 60), test (n = 10), and validation (n = 10) groups so that class labels (benign lesion or OMPD) were distributed equally in each group. A cross-validated grid search was used to optimize the hyperparameters of the Extreme Gradient Boosting (XGBoost) classifications model. Predictions were made on the test group and used to optimize the prediction threshold. The final results were validated by predictions based on the validation group. The XGBoost classification model was able to differentiate between benign intraoral lesions and OPMDs with a mean classification accuracy of 70%, sensitivity of 80%, and specificity of 60% when grayscale and enhanced color intraoral images were used. A mean classification accuracy of 50%, sensitivity of 40%, and specificity of 60% were observed when raw intraoral images were used. The results demonstrated that ML may be a promising tool for the diagnosis of OPMDs when used as an adjunct to conventional comprehensive oral examination.

Dietary fat and male sex increase histopathological changes in a mouse model of oral cancer.

OBJECTIVE: To compare the effects of dietary fat and sex on murine oral squamous cell carcinoma pathology. MATERIALS AND METHODS: Male and female C57Bl/6 mice (36/sex) received a low-fat (10 kcal%) or high-fat (60 kcal%) diet. Water (control), vehicle, or 4-nitroquinoline-1-oxide in vehicle (50 µg/ml) was provided for 17 weeks followed by six additional weeks of water. Oral lesion development was recorded weekly. Histopathologic changes in tongues were examined, and T cells (CD3+), macrophages (CD68+), and neutrophils (Ly6+) were quantified. RESULTS: All 4-nitroquinoline-1-oxide-treated mice developed oral tumors. High-fat diet exacerbated pathology, demonstrated by an increased final tumor burden (10.9 ± 4.5 vs. 7.9 ± 2.5, mm/mouse, p < .05; high-fat diet vs. low-fat diet, respectively), and a greater histopathology score. When dietary groups were combined, 4-nitroquinoline-1-oxide-treated males displayed higher histopathology scores than females (4.2 ± 0.3 vs. 3.6 ± 0.2, respectively, p < .05). Lymphoid cell infiltration was greater in the 4-nitroquinoline-1-oxide mouse tongues than controls: T cells (14.0 vs. 0.96 cells/mm2 ), macrophages (3.6 vs. 1.8 cells/mm2 ), and neutrophils (12.0 vs. 0.38 cells/mm2 ). CONCLUSION: High-fat diet and male sex increased the pathology of 4-nitroquinoline-1-oxide-induced oral cancer. Elevated lymphoid cell infiltration contributed to disease pathology.

Should Pass/Fail Grading Be Used Instead of Traditional Letter Grades in Dental Education? Two Viewpoints: Viewpoint 1: Pass/Fail Grading Improves Learning Experiences for Students and Viewpoint 2: Traditional Letter Grading Provides Objective Evaluation for Dental Education.

Discussions about which grading system (letter grade or pass/fail) is more effective in dental education have been occurring for several decades. As more institutions continue to consider the change from the traditional five-tier letter grading system (A/B/C/D/F) to a two-tier grading system (pass/fail), this debate will likely continue. This point/counterpoint article examines arguments for and against each type of grading system, taking into consideration academic performance, learning outcomes, psychological well-being, learning environment, acceptance/performance in postgraduate educational programs, and student motivation. Viewpoint 1 supports the position that a pass/fail system improves learning experiences for dental students, whereas Viewpoint 2 argues that the traditional letter grading system provides for more objectivity and reliability in student evaluation.

Angiopoietin-2 is expressed in oral Kaposi's sarcoma.

BACKGROUND: Kaposi's sarcoma (KS) persists today as a highly prevalent vascular cancer, often found in HIV patients. Studies have shown that angiopoietin 2 (Ang2), a pro-angiogenic protein, is involved in the pathogenesis of this tumor. However, expression of this protein has not been investigated in oral KS lesions. Thus, we aimed to investigate the expression of Ang2 in samples of oral KS. METHODS: Immunohistochemistry was used to evaluate Ang2 expression in 14 oral KS cases, with degrees of expression being analyzed in a semi-quantitative manner. In addition, clinical information such as age, gender, race, tumor location, size, color, and appearance, as well as HIV status, was collected and included in the analysis. RESULTS: All patients were white males, mostly HIV-positive, with a mean age of 40 years. Clinically, the lesions were dark red/blue/purple masses, ranging from 1 to 2.5 cm in diameter, found in various locations such as the tongue, palate, and gingiva. Expression of Ang2 was noted in 72% (10/14) of the samples. Of these, 10% showed weak expression, 60% moderate, and 30% strong expression. CONCLUSIONS: Our results indicate that Ang2 is expressed in oral KS and, consistent with results from previous studies, show that Ang2 may contribute to the pathogenesis of this lesion.

The Akt/mTOR pathway is activated in verrucous carcinoma of the oral cavity.

BACKGROUND: The Akt/mTOR pathway is activated in many malignancies, including oral squamous cell carcinoma (OSCC). However, the role of the Akt/mTOR pathway in oral verrucous carcinoma (OVC), a low-grade variant of OSCC, remains unknown. Thus, the objective of this study was to investigate the activation level of important markers of the Akt/mTOR pathway in OVC and to compare the results with OSCC samples. METHODS: The expression of p-Akt (Thr308), p-Akt (Ser473), and p-RPS6 was evaluated by immunohistochemistry in 30 OSCC cases, 18 OVC cases, and 30 control cases (normal epithelium overlying fibromas). Statistical analysis was performed to determine the differences in protein expression between samples. RESULTS: All OVC cases were positive for p-Akt (Thr308), p-Akt (Ser473), and p-RPS6. There were significant differences in expression level of all studied proteins between OVC and control, as well as between OVC and OSCC. However, OVC showed significant lower staining scores than OSCC. CONCLUSIONS: Our findings demonstrate that the Akt/mTOR pathway is upregulated in OVC, indicating a role for this pathway in the development and progression of this malignancy.

Oral cancer knowledge, behavior, and attitude among osteopathic medical students.

Approximately 21,000 osteopathic medical students were enrolled in the USA in 2012-2013. These future physicians are being educated with an emphasis on a holistic or patient-centered approach, with a focus on preventive care. Considering the importance of preventive care and early diagnosis in the outcomes of oral malignancies, our goal in this study was to assess the knowledge, behavior, and attitude of osteopathic medical students in relation to oral cancer. To this end, 204 second-year (Y2) and 194 fourth-year (Y4) medical students were invited to participate in an electronic survey. Forty-one Y2 and 44 Y4 students agreed to participate (20 and 22% response rate, respectively). The results showed that most Y2 and Y4 students were knowledgeable in certain areas (demographic features, important risk factors, and histologic feature), but deficient in others (clinical presentation, association of human papillomavirus (HPV) with oropharyngeal cancers, and screening recommendations). Head, neck, and oral examination habits were reported as being performed occasionally. Overall, students reported feeling uninformed about oral cancer and showed an interest in receiving further education on the subject. Our findings confirm that an overall improvement in oral cancer education in the medical curriculum is needed. Interprofessional collaboration between dental and medical schools may prove to be a valid approach to achieve this goal, which may possibly lead to increased detection of early oral cancerous lesions and, ultimately, improved mortality rates.

Traumatic neuroma of the mandible: A case report with spontaneous remission.

Traumatic neuroma is a well-known disorder involving peripheral nerves, which occurs following trauma or surgery. The lesion develops most commonly in the soft tissues of the mental foramen area, lower lip and tongue. Intra-osseous lesions arising in jawbones are very uncommon. In this paper, we report a new case of an intra-osseous traumatic neuroma, discovered incidentally on a panoramic radiograph obtained for orthodontic documentation. In addition, the case herein described developed spontaneous remission, a situation not previously reported in the literature. Finally, we discuss relevant demographic, clinical, microscopic, immunohistochemical and treatment aspects of traumatic neuromas. Key words:Amputation neuroma, traumatic neuroma, mandible, spontaneous remission.

Dental students' perceptions of the use of digital microscopy as part of an oral pathology curriculum.

Recent technological advances have allowed the computer to be turned into a microscope and therefore entailed a shift from light microscopy to digital microscopy (DM). Recent studies have shown that DM is gaining popularity in multiple academic fields, including dentistry. The aim of this study was to assess the perceptions of Midwestern University College of Dental Medicine-Illinois second-year dental students of the use of DM as a component of the institution's oral and maxillofacial pathology curriculum. After 129 students utilized DM in an oral and maxillofacial pathology course, they were asked to complete a voluntary survey regarding their perceptions of the use of DM. A total of 123 students responded, for a response rate of 95 percent; 112 of these were included in the final analysis. Nearly all the respondents (92 percent) favored DM over light microscopy. Almost all (98 percent) agreed that the digital microscope enhanced their learning, and 97 percent agreed that it allowed for greater collaboration among peers. These findings support the implementation of DM as the primary teaching methodology in the field of oral and maxillofacial pathology.

Endometrial carcinoma metastatic to the retromolar pad.

Metastatic carcinoma from the female genitalia to the oral mucosa is exceptionally rare, with only 11 such cases having been previously reported in the English-language literature. We describe a new case in a 65-year-old woman with a history of endometrial carcinoma who presented with swelling of the retromolar pad. Radiographic examination showed slight opacities and irregular trabecular bone in the left posterior mandible. Following an incisional biopsy, histologic examination and immunohistochemical studies revealed glandular adenocarcinoma with positivity for progesterone receptor, estrogen receptor, and cytokeratin 7. The patient was referred to her primary care physician for comprehensive treatment. This case illustrates the value of considering cancer metastasis in the differential diagnosis of an oral swelling, particularly in a patient with a history of cancer.

Activation of the Akt/mTOR pathway in dentigerous cysts, odontogenic keratocysts, and ameloblastomas.

OBJECTIVE: The aim of this study was to investigate the Akt/mTOR pathway in dentigerous cysts (DCs), odontogenic keratocysts (OKCs), and ameloblastomas. STUDY DESIGN: A total of 90 cases were studied (30 DCs, 30 OKCs, and 30 ameloblastomas). Patient records on age, sex, lesion location, symptoms, and radiographic and histopathologic features were collected. The phosphorylation of components of the Akt/mTOR pathway [p-Akt (Ser473), p-Akt (Thr308), and phosphorylated-ribosomal protein S6 (p-RPS6)] was studied using immunohistochemistry. Correlations with clinical features were analyzed using the Spearman rank test. RESULTS: Over 90% of OKCs and ameloblastomas and 60% of DCs stained positive for p-Akt (Ser473). Phospho-Akt (Thr308) was positive in 73% of ameloblastomas, 40% of OKCs, and 20% of DCs. Phospho-RPS6 was detected most frequently in OKCs (83%), followed by ameloblastomas (76%) and DCs (53%). No correlations were noted between the immunohistochemical findings and the clinicopathologic parameters. CONCLUSIONS: The Akt/mTOR pathway is upregulated in DCs, OKCs, and ameloblastomas. This pathway may be involved in the development of these lesions.

Solitary fibrous tumor of the parotid gland: Case report.

Solitary fibrous tumor (SFT) is a rare spindle cell neoplasm that usually develops in the pleura and peritoneum. The head and neck region is involved in only 6% of the cases. Involvement of the parotid gland is a rare phenomenon, with only 24 cases reported in the literature. The aim of this study is to report an additional case of SFT affecting the parotid gland, and to review the literature on previously reported cases. The patient was a 42-year-old male with a 4-cm, fibro-elastic, movable, painless nodule in the inferior lobe of the parotid gland. The lesion was surgically excised and, following histopathological and immunohistochemical analysis, a diagnosis of SFT was rendered. The patient has been followed-up for ten months, with no signs of recurrence. Clinical, histopathological, immunohistochemical and treatment aspects of the tumor are discussed. Key words:Solitary fibrous tumor, parotid gland, case report.

Expression of midkine in ameloblastomas and its correlation with clinicopathologic parameters.

OBJECTIVE: Midkine (MK) is a heparin-binding growth factor that is overexpressed in various human cancers. The aim of this study was to investigate the expression of MK in ameloblastomas and correlate the results with clinicopathologic parameters. STUDY DESIGN: Cases of ameloblastoma seen between 1999 and 2010 were identified. Clinical information was collected regarding age, gender, race, and location of tumor. Cases were classified as solid/multicystic, unicystic, and peripheral. The expression of midkine was assessed using immunohistochemistry. A significant difference was considered present at P < 0.05. RESULTS: A total of 34 cases of ameloblastoma and 4 cases of ameloblastic carcinomas were identified. MK was expressed in 67% of lesions (23.5% weak expression; 14.7% moderate expression; 29.4% strong expression). A significant difference was seen between solid/multicystic and unicystic lesions. CONCLUSIONS: MK is expressed in the majority of ameloblastomas, suggesting a role of the protein in the tumor's development, progression, and behavior.

Metastatic tumors to the oral cavity: a clinical study of 18 cases.

The aim of this study was to describe the clinical features of 18 cases of metastatic tumors to the oral cavity. The files of patients seen between 1992 and 2009 with oral (soft tissue and jawbones) metastatic lesions were reviewed. Clinical features, including gender, age, site of the primary tumor, site of metastatic tumor and treatment were evaluated. Patients were 11 males and 7 females, with mean age of 64.6 years. In males, most primary tumors originated in the lungs. In females, the lung and breast were the most common sites of the primary tumors. The mandible was the main site for the development of the metastatic lesions and the most common histologic type was adenocarcinoma. Treatment modalities included radiotherapy, chemotherapy and surgical resection. Metastatic lesions should be considered in the differential diagnosis of oral lesions, particularly when a previous history of cancer is present.

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 IKKß) that, in turn, converge on TSC1/2, promoting mTOR activation, HIF upregulation, and VEGF secretion. Conditioned media from vGPCR-expressing cells lead to an mTOR-dependent increase in HIF-1α and HIF-2α 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.

Angiopoietin-like 4: a novel molecular hallmark in oral Kaposi's sarcoma.

Kaposi's sarcoma (KS) remains among the most common causes of oral cancer in HIV-infected individuals. Infection with the KS-associated herpesvirus (KSHV/HHV8) is a necessary event for disease development. Emerging evidence suggests that KSHV infects vascular endothelial (or endothelial progenitor) cells promoting the formation of the KS tumor (or spindle) cell. These cells elaborate angiogenic growth factors and cytokines that promote the dysregulated angiogenesis and profuse edema that characterizes this unusual vascular tumor. Central among these secreted factors is the potent endothelial cell mitogen, vascular endothelial growth factor (VEGF). Indeed, VEGF has proven to be a key player in KSHV pathogenesis and is a molecular hallmark of KS lesions. We have recently shown that a second angiogenic factor, Angiopoietin-like 4 (ANGPTL4), may also play a critical role in KS development. Here we demonstrate that ANGPTL4 is upregulated both directly and indirectly by the KSHV oncogene, vGPCR. We further show that ANGPTL4 is a molecular hallmark of oral KS lesions. Indeed, expression of this protein was observed in more tumor cells and in more biopsies specimens than expression of VEGF (23/25 or 92% vs. 19/25 or 76%, respectively) in oral KS. These surprising results support a key role for ANGPTL4 in Kaposi's sarcomagenesis and further suggest that this angiogenic factor may provide a novel diagnostic and therapeutic marker for oral KS patients.

Viral G protein-coupled receptor up-regulates Angiopoietin-like 4 promoting angiogenesis and vascular permeability in Kaposi's sarcoma.

Kaposi's sarcoma (KS) is an enigmatic vascular tumor thought to be a consequence of dysregulated expression of the human herpesvirus-8 (HHV-8 or KSHV)-encoded G protein-coupled receptor (vGPCR). Indeed, transgenic animals expressing vGPCR manifest vascular tumors histologically identical to human KS, with expression of the viral receptor limited to a few cells, suggestive of a paracrine mechanism for vGPCR tumorigenesis. Both human and vGPCR experimental KS lesions are characterized by prominent angiogenesis and vascular permeability attributed to the release of angiogenic molecules, most notably vascular endothelial growth factor. However, the relative contribution of these paracrine mediators to the angiogenic and exudative phenotype of KS lesions remains unclear. Here we show that vGPCR up-regulation of Angiopoietin-like 4 (ANGPTL4) plays a prominent role in promoting the angiogenesis and vessel permeability observed in KS. Indeed, ANGPTL4 expression is a hallmark of vGPCR experimental and human KS lesions. Inhibition of ANGPTL4 effectively blocks vGPCR promotion of the angiogenic switch and vascular leakage in vitro and tumorigenesis in vivo. These observations suggest that ANGPTL4 is a previously unrecognized target for the treatment of patients with KS. As angiogenesis and increased vessel permeability are common themes in all solid tumors, these findings may have a broad impact on our understanding and treatment of cancer.

The Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor: Lessons on dysregulated angiogenesis from a viral oncogene.

Tumor viruses can induce cell transformation by overcoming cellular defense mechanisms and promoting the ungoverned proliferation of infected cells. To this end, functionally related viral oncogenes have evolved in disparate viruses to over-ride key proliferative and survival intracellular pathways, thus assuring efficient viral replication and contributing to tumor formation. Indeed, the study of viral oncogenes has been a powerful tool for disclosing fundamental insights into these basic cellular processes. In this regard, the Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8), the etiological agent of Kaposi's sarcoma (KS), is an exemplary model of an oncogenic virus that includes within its genome several homologues of cellular genes implicated in the regulation of cell proliferation and apoptosis. However, emerging evidence now points to a single KSHV gene, ORF74, encoding for the viral G protein-coupled receptor (vGPCR), as essential for KS development. Expressed in only a fraction of cells within KS lesions, this viral receptor induces tumorigenesis through both autocrine and paracrine mechanisms. Indeed, work from several laboratories has demonstrated that vGPCR can promote cell proliferation, enhance cell survival, modulate cell migration, stimulate angiogenesis, and recruit inflammatory cells, both in expressing cells, as well as in neighboring (bystander) cells. Examination of this powerful viral oncogene may expose novel targets for the treatment of patients with KS and could ultimately provide a unique perspective into how GPCRs, and specifically chemokine receptors, contribute to angiogenesis and tumorigenesis.