Tumour-associated tissue eosinophilia (TATE) in oral squamous cell carcinoma: a comprehensive review

Panoramic view of key cross-talks underpinning the oral squamous cell carcinoma stemness - unearthing the future opportunities

The clinical management of oral cancer is often frequented with challenges that arise from relapse, recurrence, invasion and resistance towards the cornerstone chemo and radiation therapies. The recent conceptual advancement in oncology has substantiated the role of cancer stem cells (CSC) as a predominant player of these intricacies. CSC are a sub-group of tumor population with inherent adroitness to self-renew with high plasticity. During tumor evolution, the structural and functional reprogramming persuades the cancer cells to acquire stem-cell like properties, thus presenting them with higher survival abilities and treatment resistance. An appraisal on key features that govern the stemness is of prime importance to confront the current challenges encountered in oral cancer. The nurturing niche of CSC for maintaining its stemness characteristics is thought to be modulated by complex multi-layered components encompassing neoplastic cells, extracellular matrix, acellular components, circulatory vessels, various cascading signaling molecules and stromal cells. This review focuses on recapitulating both intrinsic and extrinsic mechanisms that impart the stemness. There are contemplating evidences that demonstrate the role of transcription factors (TF) in sustaining the neoplastic stem cell's pluripotency and plasticity alongside the miRNA in regulation of crucial genes involved in the transformation of normal oral mucosa to malignancy. This review illustrates the interplay between miRNA and various known TF of oral cancer such as c-Myc, SOX, STAT, NANOG and OCT in orchestrating the stemness and resistance features. Further, the cross-talks involved in tumor micro-environment inclusive of cytokines, macrophages, extra cellular matrix, angiogenesis leading pathways and influential factors of hypoxia on tumorigenesis and CSC survival have been elucidated. Finally, external factorial influence of oral microbiome gained due to the dysbiosis is also emphasized. There are growing confirmations of the possible roles of microbiomes in the progression of oral cancer. Given this, an attempt has been made to explore the potential links including EMT and signaling pathways towards resistance and stemness. This review provides a spectrum of understanding on stemness and progression of oral cancers at various regulatory levels along with their current therapeutic knowledge. These mechanisms could be exploited for future research to expand potential treatment strategies.

The Emerging Impact of Tumor Budding in Oral Squamous Cell Carcinoma: Main Issues and Clinical Relevance of a New Prognostic Marker

Tumor Budding (TB) represents a single cancer cell or a small cluster of less than five cancer cells on the infiltrative tumor front. Accumulating evidence suggests TB is an independent prognostic factor in oral squamous cell carcinoma (OSCC). However, its exact role is not yet elucidated, and a standardized scoring system is still necessary. The study aims to extensively review the literature data regarding the prognostic role of TB in OSCC. The results of TB are an independent prognostic factor of poor survival outcomes in OSCC. To date, the manual detection of hematoxylin and eosin-staining or pancytokeratin-immunostaining sections are the most commonly used methods. Between the several cut-offs, the two-tier system with five buds/field cut-offs provides better risk stratification. The prognostic role of the BD model in predicting survival outcomes was extensively validated; however, the inclusion of DOI, which is already a staging parameter, encouraged other authors to propose other models, integrating TB count with other adverse risk factors, such as the tumor–stroma ratio and tumor-infiltrated lymphocytes. The prognostic relevance of TB in OSCC highlights its evaluation in daily pathological practice. Therefore, the TB detection method and the TB scoring system should be validated based on tumor stage and site.

Role of Salivary MicroRNA and Cytokines in the Diagnosis and Prognosis of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most prevalent oral malignant tumor worldwide. An early diagnosis can have a major positive impact on its prognosis. Human saliva contains cytokines, DNA and RNA molecules, circulating cells, and derivatives of tissues and extracellular vesicles, among other factors that can serve as biomarkers. Hence, the analysis of saliva may provide useful information for the early diagnosis of OSCC for its prognosis. The objective of this review was to determine the potential usefulness of salivary biomarkers (cytokines and microRNA) to diagnose OSCC and improve its prognosis. A combination of salivary miRNA and proteomic data could allow a definitive and early diagnosis to be obtained. However, there remains a need to optimize and standardize the protocols used to quantify miRNAs.

The Ratio of Preoperative Serum Biomarkers Predicts Prognosis in Patients With Oral Squamous Cell Carcinoma

Background

Dynamic changes in circulating immune-inflammatory cells have been regarded as simple and convenient prognostic biomarkers in various cancers. However, studies on the prognostic values of their ratios in oral squamous cell carcinoma (OSCC) remain limited.

Materials and Methods

A total of 493 OSCC patients were included in the present study. Here, we investigated the prognostic values of the neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), neutrophil-to-white blood cell ratio (NWR), and lymphocyte-to-white blood cell ratio (LWR) in OSCC. The correlations of the NLR, LMR, NWR, and LWR with clinicopathological characteristics were statistically analyzed using the Chi-square test, Kaplan-Meier curves, and univariate and multivariate Cox regression models.

Result

Kaplan-Meier analyses revealed that OSCC patients with a high LMR and low NWR had prolonged overall survival (OS, P<0.001) and disease-free survival (DFS, P<0.001 and P=0.003, respectively), but there were no significant differences in metastasis-free survival (MFS, P=0.053 and P=0.052, respectively). In contrary, a high NLR and low LWR were associated with poor OS (P<0.001 and P=0.0016, respectively), DFS (P=0.0014 and 0.0012, respectively) and MFS (P=0.021 and 0.008, respectively). Additionally, Cox multivariate analyses showed that the LMR was an independent prognostic factor for both OS (P=0.007) and DFS (P=0.017), while the LWR was an independent prognostic factor for MFS (P=0.009).

Conclusion

Preoperative NLR, LMR, NWR, and LWR in the peripheral blood are significant prognostic factors for OSCC and might be helpful in predicting OSCC progression.

Immunity and Breast Cancer: Focus on Eosinophils

The role of eosinophils, a cell type involved in the immune response to parasitic infections and allergies, has been investigated in different cancer types, in both tumor tissue and at the circulating level. Most studies showed a role mainly in conjunction with immunotherapy in melanomas and lung tumors, while few data are available in breast cancer. In this review, we summarize literature data on breast cancer, showing a prognostic role of circulating eosinophil counts as well as of the presence of tumor tissue infiltration by eosinophils. In particular, some studies showed an association between a higher circulating eosinophil count and a good prognosis, as well as an association with response to neoadjuvant chemotherapy in hormone receptor-negative/HER2-positive and in triple negative breast cancer. Several mechanistic studies have also been conducted in in vivo models, but the exact mechanism by which eosinophils act in the presence of breast cancer is still unknown. Further studies on this subject are desirable, in order to understand their role at the cellular level, identify related biomarkers and/or possibly search for new therapeutic targets.