An overview of oral carcinogenesis

Correlation of PD-1 and PD-L1 expression in oral leukoplakia and oral squamous cell carcinoma: an immunohistochemical study

The programmed cell death protein (PD-1)/programmed cell death protein ligand (PD-L1) pathway and cytotoxic T lymphocyte antigen are the most important co-stimulatory molecules that play a key role in the negative regulation of T cells during carcinogenesis. We aimed to evaluate the immunohistochemical expression of PD-1 and PD-L1 in oral leukoplakia and squamous cell carcinoma compared with normal oral mucosa. Twenty-five cases of oral squamous cell carcinoma, oral leukoplakia and normal oral mucosa tissue specimens were immunohistochemically stained to assess PD-1 and PD-L1 expression. The PD-L1 positivity of subepithelial TAFs (p < 0.001) increased with increasing grades of oral leukoplakia. Pearson's correlation indicated a high positive correlation between the PD-L1 labelling index of epithelial tumour cells and the PD-1 labelling index of tumour infiltrating lymphocytes (p value: 0.005) in OSCC. A high positive correlation was noted between the H-score of PD-L1 positive tumour epithelial cells and the H-score of PD-1 positive tumour infiltrating lymphocytes in OSCC (p value: 0.001). PD-L1 positivity increased in dysplastic epithelial cells from premalignant lesions to malignancy. The sub-epithelial PD-L1 positive TAFs were higher in oral leukoplakia compared to OSCC inferring that PD-L1 positivity in TAFs decreased with malignant transformation. The PD-1 positivity in TILs was higher in oral leukoplakia than in OSCC.

Effect of Harvey Rat Sarcoma Virus Mutation in Oral Squamous Cell Carcinoma and Its Influence on Different Populations: A Systematic Review

The information for protein synthesis is given by the genes. These proteins are responsible for controlling functions like cell growth, differentiation, cell maturation, and cell death. In the case of genetic mutations, the protein functions get disturbed leading to a drastic shift in the normal physiological functions of cell growth, differentiation, and proliferation, making the normal cell cancerous. The Harvey rat sarcoma virus (HRAS) gene is an oncogene that belongs to the rat sarcoma virus (RAS) family. HRAS gene provides the instructions for making the HRAS protein that plays an important role in regulating cell division and when the HRAS gene gets mutated it gets involved in initiating cancer. HRAS mutation has been frequently noted in head and neck cancers; however, the mechanism of HRAS mutation involved in the initiation of oral squamous cell carcinoma (OSCC) still remains unexplored. An elaborate systematic literature search was done in PubMed, Scopus, and Web of Science databases. It was found that the Ras-dependent mutations affect the involved upstream and downstream components of the Ras-Raf-MAPK (rat sarcoma virus-rapidly accelerated fibrosarcoma-mitogen-activated protein kinase) pathway deregulating the signal leading to tumorigenesis. The Ras mutation can affect the Ras-Raf-MAPK pathway at different stages. The disease caused is based on the frequency of the HRAS mutation and it can lead to diverse cellular outcomes as it is mainly associated with cell division, differentiation, growth, survival, and the cell cycle. The crosstalk between the signaling pathways is controlled by the signaling molecules resulting in the creation of molecular networks. The balance of these molecular networks is very important to determine the cellular outcome. This systematic review inspects the molecular network of HRAS and its vital role in carcinogenesis. It is aimed at exploring and summarizing the contributions of the HRAS mutation involved in the pathogenesis of OSCC.

Boronic acid derivative activates pyruvate kinase M2 indispensable for redox metabolism in oral cancer cells

PKM2is considered a desirable target as its enzymatic activation is expected to cause a diminution in tumorigenesis and prevent limitless replication in cancerous cells. However, considering the functional consequences of kinase inhibitors, the design of PKM2 activators has been an attractive strategy that has yielded potent anticancer molecules like DASA-58. Therefore, a new class of boronic acid derivate was developed to elucidate the possible mechanistic link between PKM2 activation and TPI1 activity, which has a significant role in the redox balance in cancer. The present in vitro study revealed that treatment with boronic acid-based compound 1 and DASA-58 was found to activate PKM2 with an AC50 of 25 nM and 52 nM, respectively. Furthermore, at the AC50 concentration of compound 1, we found a significant increase in TPI1 activity and a decrease in GSH and NADP+/NADPH ratio. We also found increased ROS levels and decreased lactate secretion with treatment. Together with these findings, we can presume that compound 1 affects the redox balance by activating PKM2 and TPI1 activity. Implementation of this treatment strategy may improve the effect of chemotherapy in the conditions of ROS induced cancer drug resistance. This study for the first time supports the link between PKM2 and the TPI1 redox balance pathway in oral cancer. Collectively, the study findings provide a novel molecule for PKM2 activation for the therapeutic intervention in oral cancer.

Advanced diagnostic aids for oral cancer

Oral cancer, a universal malady, has become a stumbling block over the years due to its significant morbidity and mortality rates. The greater morbidity associated with this deadly disease is attributed to delay in its diagnosis / its presentation in advanced stage. Being multifactorial, Oral squamous cell carcinoma (OSCC) is the outcome of genetic and epigenetic instability. However, in many instances, oral cancer is preceded by precursor lesions named as oral potentially malignant disorders (OPMDs), the early detection of which makes it beneficial for patients with the possible increase in the productive longevity. Many diagnostic tools / aids have been explored with the aim of early detection of oral precancer and cancer. The basic chair-side procedures or relatively advanced aids come with a set of limitations along with subjectivity as one of the setbacks. The advent and exploitation of molecular techniques in the field of health diagnostics, is demanding the molecular typing of the OPMDs and also of oral cancer. The saga of various diagnostic aids for OSCC has witnessed the so-called latest trends such as lab-on-chip, microfluidics, nano diagnostics, liquid biopsy, omics technology and synthetic biology in early detection of oral precancer and cancer. Oral cancer being multifactorial in origin with the chief participation of altered genetics and epigenetics would demand high-end diagnostics for designing personalized therapy. Hence, the present paper highlights the role of various advanced diagnostic aids including 'omics' technology and synthetic biology in oral precancer and cancer.

Progress in Drug and Formulation Development for the Chemoprevention of Oral Squamous Cell Carcinoma: A Review

BACKGROUND

Cancer is a life-threatening global problem with high incidence rates. Prioritizing the prevention of cancer, chemopreventive agents have drawn much attention from the researchers.

OBJECTIVE

This review focuses on the discussion of the progress in the development of chemopreventive agents and formulations related to the prevention of oral cancer.

METHODS

In this perspective, an extensive literature survey was carried out to understand the mechanism, control and chemoprevention of oral cancer. Different patented agents and formulations have also exhibited cancer preventive efficacy in experimental studies. This review summarizes the etiology of oral cancer and developments in prevention strategies.

RESULTS

The growth of oral cancer is a multistep activity necessitating the accumulation of genetic as well as epigenetic alterations in key regulatory genes. Many risk factors are associated with oral cancer. Genomic technique for sequencing all tumor specimens has been made available to help detect mutations. The recent development of molecular pathway and genetic tools has made the process of diagnosis easier, better forecast and efficient therapeutic management. Different chemical agents have been studied for their efficacy to prevent oral cancer and some of them have shown promising results.

CONCLUSION

Use of chemopreventive agents, either synthetic or natural origin, to prevent carcinogenesis is a worthy concept in the management of cancers. Preventive measures are helpful in controlling the occurrence or severity of the disease. The demonstrated results of preventive agents have opened an arena for the development of promising chemopreventive agents in the management of oral squamous cell carcinoma.