Role of inflammation in oral carcinogenesis (Part I): Histological grading of malignancy using a binary system

Overview of Oral Potentially Malignant Disorders: From Risk Factors to Specific Therapies

Oral squamous cell carcinoma (OSCC) is a very aggressive cancer, representing one of the most common malignancies worldwide. Oral potentially malignant disorders (OPMDs) regroup a variegate set of different histological lesions, characterized by the potential capacity to transform in OSCC. Most of the risk factors associated with OSCC are present also in OPMDs' development; however, the molecular mechanisms and steps of malignant transformation are still unknown. Treatment of OSCC, including surgery, systemic therapy and radiotherapy (alone or in combination), has suffered a dramatic change in last years, especially with the introduction of immunotherapy. However, most cases are diagnosed during the advanced stage of the disease, decreasing drastically the survival rate of the patients. Hence, early diagnosis of premalignant conditions (OPMDs) is a priority in oral cancer, as well as a massive education about risk factors, the understanding of mechanisms involved in malignant progression and the development of specific and more efficient therapies. The aim of this article is to review epidemiological, clinical, morphological and molecular features of OPMDs, with the purpose to lay the foundation for an exhaustive comprehension of these lesions and their ability of malignant transformation and for the development of more effective and personalized treatments.

Oral potentially malignant disorders: new insights for future treatment

PURPOSE OF REVIEW

The purpose of this review is to define the issues regarding oral potentially malignant disorders (OPMDs) and provide an overview of currently available treatments and ongoing clinical trials for future opportunities.

RECENT FINDINGS

Nowadays, the treatment of choice of OPMD is surgery, whose role in preventing malignant transformation is however limited because of the high rate of recurrence and field cancerization. There have been several attempts of combining systemic therapies with surgery to reduce risk of malignant transformation. The identification of biomarkers that could predict malignant transformation is crucial in better tailoring the risk profile and possible therapeutic approaches.

SUMMARY

Loss of heterozygosity remains the most predictive marker of malignant transformation; however, role of specific microRNA and OPMD immune infiltration are emerging as potential biomarkers. Given the failure of previous trials with various chemopreventive strategies, new strategies should be defined to address the issue of systemic prevention of malignant transformation. Recent updates about immune infiltration and the immune-equilibrium concept for OPMD could shed light into new preventive approaches.

Evaluation of Proinflammatory, NF-kappaB Dependent Cytokines: IL-1α, IL-6, IL-8, and TNF-α in Tissue Specimens and Saliva of Patients with Oral Squamous Cell Carcinoma and Oral Potentially Malignant Disorders

Background: Oral squamous cell carcinoma (OSCC) is a life-threatening disease. It could be preceded by oral potentially malignant disorders (OPMDs). It was confirmed that chronic inflammation can promote carcinogenesis. Cytokines play a crucial role in this process. The aim of the study was to evaluate interleukin-1alpha (IL-1α), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) in tissue specimens and saliva of patients with OSCC and OPMDs. Methods: Cytokines were evaluated in 60 tissue specimens of pathological lesions (OSCCs or OPMDs) and in 7 controls (normal oral mucosa, NOM) by immunohistochemistry and in saliva of 45 patients with OSCC or OPMDs and 9 controls (healthy volunteers) by enzyme-linked immunosorbent assays. Results: Immunohistochemical analysis revealed significantly higher expression of IL-8 in OSCC specimens and TNF-α in OSCCs and OPMDs with dysplasia as compared to NOM. Moreover, expression of TNF-α was significantly higher in oral leukoplakia and oral lichen planus without dysplasia, whereas expression of IL-8 only in oral leukoplakia without dysplasia in comparison with NOM. Salivary concentrations of all evaluated cytokines were significantly higher in patients with OSCC than in controls. Moreover, levels of IL-8 were significantly higher in saliva of patients with OPMDs with dysplasia as compared to controls and in OSCC patients as compared to patients with dysplastic lesions. There was also significant increase in salivary concentrations of IL-6, IL-8 and TNF-α in patients with OSCC as compared to patients with OPMDs without dysplasia. Conclusion: The study confirmed that proinflammatory, NF-kappaB dependent cytokines are involved in pathogenesis of OPMDs and OSCC. The most important biomarker of malignant transformation process within oral mucosa among all assessed cytokines seems to be IL-8. Further studies on a larger sample size are needed to corroborate these results.

Fatty acids distribution and content in oral squamous cell carcinoma tissue and its adjacent microenvironment

Squamous cell carcinoma of the oral cavity mucosa grows under conditions of poor oxygenation and nutrient scarcity. Reprogramming of lipid biosynthesis accompanies tumor growth, but the conditions under which it occurs are not fully understood. The fatty acid content of the serum, tumor tissue and adjacent tumor microenvironment was measured by gas chromatography in 30 patients with squamous cell carcinoma grade 1-3. Twenty-five fatty acids were identified; their frequencies and percentages in each of the environments were assessed. Nineteen of the twenty-five fatty acids were found in tumor tissue, tumor adjacent tissue and blood serum. Of them, 8 were found in all thirty patients. Percentages of C16:0 and C18:1n9 were highest in the tumor, C18:1n9 and C16:0 were highest in tumor adjacent tissue, and C16:0 and C18:0 were highest in blood serum. The frequencies and amounts of C22:1n13, C22:4n6, C22:5n3 and C24:1 in tumor adjacent tissues were higher than those in blood serum, independent of the tumor grade. The correlations between the amount of fatty acid and tumor grade were the strongest in tumor adjacent tissues. The correlations between particular fatty acids were most prevalent for grade 1+2 tumors and were strongest for grade 3 tumors. In the adjacent tumor microenvironment, lipogenesis was controlled by C22:6w3. In blood serum, C18:1trans11 limited the synthesis of long-chain fatty acids. Our research reveals intensive lipid changes in oral cavity SCC adjacent to the tumor microenvironment and blood serum of the patients. Increase in percentage of some of the FAs in the path: blood serum-tumor adjacent microenvironment-tumor, and it is dependent on tumor grade. This dependency is the most visible in the tumor adjacent environment.

Reduced CD8+ T cells infiltration can be associated to a malignant transformation in potentially malignant oral epithelial lesions

OBJECTIVE

The aim of this study was to evaluate the immunohistochemical expressions of PD1, CD4⁺, and CD8⁺ in premalignant lesions (OPML) that were transformed into oral squamous cell carcinoma OSCC (OPML-OSCC), in OSCC and also in premalignant lesions that were not transformed into OSCC (OPML-NOSSC).

MATERIALS AND METHODS

Retrospective analyses were performed in order to verify the demographic characteristics of the patients. CD4, CD8, and PD1 IMH studies were carried out on OPML and OSCC samples from 11 patients with OPML-OSCC and OPML, together with samples from 14 patients with OPML-NOSCC. The differences between OPML-OSCC and OPML-NOSCC were analyzed.

RESULTS

Non-homogenous leukoplakia, together with the related oral subsite, and the lack of an exposure to tobacco, were all associated with malignant transformations. There were no statistical differences in the PD1 expression and the CD4⁺ cells in OPML-OSCC and OPML-NOSCC. A significant increment in the CD8⁺ cells was noted in the OPML that evolved into carcinomas when compared with OPML-NOSCC (p = 0.05), whereas there were higher CD8⁺ cells levels in the carcinomas when compared with the OPML that evolved into carcinomas (p = 0.027).

CONCLUSIONS

CD8⁺ cells infiltrate more in OPML-NOSCC than in OPML-OSCC. Carcinoma is more infiltrated by CD8⁺ cells than its associated OPML.

CLINICAL RELEVANCE

Understanding immunological factors associated with malignant transformation of oral premalignant lesions can open a new way to treat this disease.

Human Head and Neck Squamous Cell Carcinoma-Associated Semaphorin 4D Induces Expansion of Myeloid-Derived Suppressor Cells

One of the mechanisms by which malignancies can induce immune suppression is through the production of cytokines that affect the maturation and differentiation of inflammatory cells in the tumor microenvironment. Semaphorin 4D (Sema4D) is a proangiogenic cytokine produced by several malignancies, which has been described in the regulation of the immune system. In the present study, we examined the role of human head and neck squamous cell carcinoma (HNSCC)-secreted Sema4D on myeloid cell differentiation. CD33(+) cells cultured in HNSCC cell line-derived conditioned medium differentiated into myeloid derived suppressor cells (MDSC) (CD33(+)CD11b(+)HLA-DR(-/low)). The addition of anti-Sema4D Ab to HNSCC conditioned medium significantly reduced the expansion of the MDSC population. Similarly, knockdown of Sema4D in an HNSCC cell line resulted in a loss of MDSC function as shown by a decrease in the production of the immune-suppressive cytokines arginase-1, TGF-β, and IL-10 by MDSC, concomitant with recovery of T cell proliferation and IFN-γ production following stimulation of CD3/CD28. Importantly, CD33(+) myeloid and T cells cultured in conditioned medium of HNSCC cells in which Sema4D was knocked down promoted antitumor inflammatory profile, through recovery of the effector T cells (CD4(+)T-bet(+) and CD8(+)T-bet(+)), as well as a decrease in regulatory T cells (CD4(+)CD25(+)FOXP3(+)). We also showed that Sema4D was comparable to GM-CSF in its induction of MDSC. Collectively, this study describes a novel immunosuppressive role for Sema4D in HNSCC through induction of MDSC, and it highlights Sema4D as a therapeutic target for future studies to enhance the antitumorigenic inflammatory response in HNSCC and other epithelial malignancies.

Morphometry As a Diagnostic Tool for Potentially Malignant Lesions

INTRODUCTION

Though we are in 21(st) century with nano technology & tissue printing, there still exist many lacunae in the field of diagnosis. Not much is known about prognostic markers till now from literature to assess potentially malignant lesions. Lesions so called potentially malignant can be termed only after clinical & malignant changes have been developed and there are no means of predicting with certainty the risk of cancerous transformation.

AIM

Our present study was undertaken to establish the morphometric parameters of the parabasal and spinous cells of normal oral epithelium with the changes occurring in cells of Oral Leukoplakia (OL), Oral Verrucous Carcinoma (OVC) and Oral Squamous Cell Carcinoma (OSCC).

MATERIALS AND METHODS

Total 40 patients were divided into Group I which includes patients with normal oral mucosa, group II oral leukoplakia patients, group III oral verrucous carcinoma patients and group IV includes oral squamous cell carcinoma patients. Tissue sections were taken and morphometric analysis of cell area, cell diameter, nuclear area, nuclear diameter, nuclear cytoplasmic ratio was done for parabasal and spinous layer cells. Statistical analysis was done using one-way ANOVA and T-test.

RESULTS

Nuclear diameter, nuclear area, cell area, nuclear cytoplasmic ratio were significantly increased in OL, OVC, OSCC patients than normal oral mucosa, which was statistically significant. Cell diameter was decreased in OL, OVC, OSCC patients than with normal oral mucosa which was statistically significant.

CONCLUSION

Cellular & nuclear parameters showed statistically significant changes in oral leukoplakia, oral verrucous carcinoma & oral squamous cell carcinoma in comparison with normal oral mucosa.

The prognostic value of histopathological grading systems in oral squamous cell carcinomas

OBJECTIVE

This study evaluated the association of four histopathological grading systems (WHO grading system, malignancy grading of the deep invasive margins (MG), histological risk (HR) model, and tumor budding and depth of invasion (BD) model) with clinicopathological parameters and outcome of 113 oral squamous cell carcinomas to identify their roles in prognosis.

METHODS

Demographic and clinical features were obtained from patients' records. Sections from all paraffin-embedded blocks were evaluated according to the four grading systems. Demographic and clinical associations were analyzed using chi-square test, and correlations between the grading systems were established with the Spearman's rank correlation test. Survival curves were performed with Kaplan-Meier method, and multivariate analysis based on Cox proportional hazard model was calculated.

RESULTS

Significant associations with survival were observed for WHO grading system and BD model in the univariate analysis, but only the BD model was significantly associated with disease outcome as an independent prognostic marker. Age, tumor size, and presence of regional metastasis were also independent markers of reduced survival.

CONCLUSION

A significant association between the BD model and outcome of OSCC patients was observed, indicating this new histopathological grading system as a possible prognostic tool.

Role of inflammation in oral carcinogenesis (Part II): CD8, FOXP3, TNF-α, TGF-β and NF-κB expression

Due to the frequent presence of inflammation in cases of carcinoma and its use as a parameter for the assessment of tumor aggressiveness, the role of inflammation in oral carcinogenesis was investigated. This was performed by evaluating the expression of cellular markers, cytokines and nuclear transcription factors that identify the cells that participate in the antitumor defense in cases of oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC). A semi-quantitative immunohistochemical analysis was performed for the transcription factors cluster of differentiation 8 (CD8), forkhead box P3 (FOXP3), transforming growth factor (TGF)-β, tumor necrosis factor (TNF)-α and nuclear factor κ-light chain enhancer of activated B-cells (NF-κB), in cases of OED and OSCC. CD8, TGF-β, TNF-α and NF-κB participated in the processes of tumor transformation and progression. The presence of inflammatory infiltrate in cases of OED favors the transformation and invasion process when stromal TNF-α and NF-kB are overexpressed, as NF-kB activated by TNF-α during inflammation predisposes the lesion to transformation, functioning as a link between inflammation and cancer. The control of these inflammatory mediators may prevent malignant transformation in the oral cavity.