Differential expression of programmed death-1 and its ligand, programmed death ligand-1 in oral squamous cell carcinoma with and without oral submucous fibrosis

Radiotherapy upregulated immune checkpoints contribute to the development of second primary OSCC

OBJECTIVES

Radiation injury is common after radiotherapy for head and neck cancer. Radiotherapy can reshape the immune microenvironment and cause immunosuppression, including dysregulation of immune checkpoints (ICs). However, the relationship between oral ICs expression after radiation and the development of second primary tumors is unclear.

METHODS

Clinical specimens of second primary oral squamous cell carcinoma after radiotherapy (s-OSCC) and primary OSCC (p-OSCC) were collected. The expression and prognostic value of PD-1, VISTA, and TIM-3 were analyzed using immunohistochemistry. To further clarify the relationship between radiation and ICs alteration, a rat model was constructed to explore the spatiotemporal changes of ICs in the oral mucosa after radiation.

RESULTS

In carcinoma tissue, the expression of TIM-3 was higher in s-OSCC than in p-OSCC, while the expression of PD-1 and VISTA was similar between the groups. In para-carcinoma tissue, the expression of PD-1, VISTA, and TIM-3 was higher in s-OSCC. High ICs expression was associated with poor survival. In the rat model, ICs were locally upregulated in the irradiated tongue. Moreover, there was a bystander effect, in which the ICs were also upregulated in the unirradiated site.

CONCLUSION

Radiation may upregulate ICs expression in oral mucosa and contribute to the development of s-OSCC.

Change and pathological significance of glycogen content in oral squamous cell carcinoma and oral submucous fibrosis

OBJECTIVE

This study aimed to investigate the change and pathological significance of glycogen content in oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF).

METHODS AND MATERIALS

13 normal oral mucosa (NOM), 12 OSF mucosa, and 35 pairs of OSCC tissues and their corresponding adjacent mucosa tissues (AT) were collected from Xiangya Hospital for PAS staining to detect glycogen. Transcriptome sequencing data from OSCC were used to compare glycogen metabolism gene expression differences. Kaplan-Meier method was conducted to estimate Recurrence-free survival (RFS).

RESULTS

Glycogen levels were lower in OSF than in NOM and lower in OSCC than in AT. Transcriptome sequencing data analysis showed the expression of most glycogenolysis genes was increased and the expression of glycogen synthesis genes including PPP1R3C and GBE1 was decreased in OSCC tissues. High glycogen level was correlated with poor prognosis in OSCC patients under the background of OSF.

CONCLUSION

Glycogen may be used as a potential diagnostic biomolecule for OSF and OSCC, as well as a potential prognostic factor for OSCC in the context of OSF.

Mechanisms and markers of malignant transformation of oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic premalignant disease associated with betel quid chewing. Epidemiological studies indicate that there are approximately 5 million individuals suffering from OSF worldwide, with a concerning malignancy transformation rate of up to 4.2 %. When OSF progresses to oral squamous cell carcinoma (OSCC), the 5-year survival rate for OSCC drops to below 60 %. Therefore, early screening and diagnosis are essential for both preventing and effectively treating OSF and its potential malignant transformation. Numerous studies have shown that the malignant transformation of OSF is associated with various factors, including epigenetic reprogramming, epithelial-mesenchymal transition, hypoxia, cell cycle changes, immune regulation disturbances, and oxidative damage. This review article focuses on the unraveling the potential mechanisms underlying the malignant transformation of OSF, as well as the abnormal expression of biomarkers throughout this transformative process, with the aim of aiding early screening for carcinogenic changes in OSF. Furthermore, we discuss the significance of utilizing blood and saliva components from patients with OSF, along with optical diagnostic techniques, in the early screening of OSF malignant transformation.

[Oral squamous cell carcinoma in the background of oral submucous fibrosis - a systematic review]

Oral squamous cell carcinoma (OSCC) in the background of oral submucous fibrosis (OSMF) is one of the most common presentations of oral cancer among Asian population. OSCC arising in the background of OSMF (OSCC with OSMF) has been a topic of interest among researchers recently and a few studies have considered this to be a distinct clinicopathological entity. This systematic review analyses the demographic and clinicopathological variations of OSCC with OSMF from conventional OSCC to evaluate the distinctiveness of OSCC with OSMF. A comprehensive search from PubMed, Google scholar and manual search were carried out and 4 articles were retrieved and analysed systematically. Out of the total 377 OSCC with OSMF cases and 542 conventional OSCC, males were found to be predominantly affected (82.7% and 73.6%). 47% of the OSCC with OSMF cases were well differentiated squamous cell carcinomas as against 33.4% in conventional OSCC. Lymph node metastases were seen predominantly in conventional OSCC (49.1%) than OSCC with OSMF cases (40.7%). OSCC with OSMF were more prevalent in males and showed better tumour differentiation and lesser lymph node metastasis. Even though the present results inculpate OSCC with OSMF as a distinct clinicopathological entity, there is a dire need for thorough investigation.

Crosstalk between PD-L1 and Jak2-Stat3/ MAPK-AP1 signaling promotes oral cancer progression, invasion and therapy resistance

BACKGROUND

Programmed cell death ligand-1 (PD-L1)is an antitumor immunity molecule and a great target to cure oral cancer; nonetheless, the limited success can be attributed to many complex pathways and tumor-related interferences.

METHODS

In the present study, 150 human oral squamous cell carcinoma (OSCC) tissue samples, including 17 adjacent normals, 56 primary tumors, 47 invasive tumors, and 30 therapy-resistant (RT) samples, were included. The parental/cisplatin-resistant (CisR-SCC4/9) cells were utilized for overexpression (Jak1-3 wild type and catalytically inactive), knockdown (PD-L1 siRNA), targeting MAPK/PI3K/Jak-Stat pathways (SMIs) and checking microsomes. The expression of PD-L1, transcription factors (TFs), signaling pathways, survival/apoptosis, therapy resistance, and invasiveness-related molecules/their activity were determined by RT-PCR, Immunohistochemistry, Western blot, Gelatin Zymography, and MTT assay.

RESULTS

Advanced OSCC tumors (invasive and drug-resistance), CisR-SCC4/9 cells, and secretory exosomes (CisR-SCC4/9) were found with increased PD-L1 expression. PD-L1 mRNA/protein showed a positive correlation with different TFs (AP1 > Stat3 > c-myc > NFκB) in tumor samples. The PD-L1 expression was more influenced by Jak-Stat/ MAPK-AP1 pathways over PI3K. The ectopic expression of Jak1-3 suggests Jak2 inducted PD-L1 level over Jak1/Jak3. Finally, PD-L1 directly supports survival (Bcl-xL, Bax, cleaved caspase-3), invasion (MMP2/9), and drug-resistance (ALDH-1A1/-3A1) program in OSCC through its link with several molecules.

CONCLUSIONS

PD-L1 was regulated mainly by the Jak2-Stat3/ MAPK-AP1 pathway, and besides the routine immunological functions, it supports OSCC survival, invasion, and therapy resistance. PD-L1 can be used as an indicator of severity and can be targeted along with Jak2-Stat3/ MAPK-AP1 for a better outcome OSCC.

PD-1/PD-L1 axis in organ fibrosis

Fibrosis is a pathological tissue repair activity in which many myofibroblasts are activated and extracellular matrix are excessively accumulated, leading to the formation of permanent scars and finally organ failure. A variety of organs, including the lung, liver, kidney, heart, and skin, can undergo fibrosis under the stimulation of various exogenous or endogenous pathogenic factors. At present, the pathogenesis of fibrosis is still not fully elucidated, but it is known that the immune system plays a key role in the initiation and progression of fibrosis. Immune checkpoint molecules are key regulators to maintain immune tolerance and homeostasis, among which the programmed cell death protein 1/programmed death ligand 1 (PD-1/PD-L1) axis has attracted much attention. The exciting achievements of tumor immunotherapy targeting PD-1/PD-L1 provide new insights into its use as a therapeutic target for other diseases. In recent years, the role of PD-1/PD-L1 axis in fibrosis has been preliminarily explored, further confirming the close relationship among PD-1/PD-L1 signaling, immune regulation, and fibrosis. This review discusses the structure, expression, function, and regulatory mechanism of PD-1 and PD-L1, and summarizes the research progress of PD-1/PD-L1 signaling in fibrotic diseases.

Overexpression of DEC1 in the epithelium of OSF promotes mesenchymal transition via activating FAK/Akt signal axis

BACKGROUND

Previous studies on oral submucous fibrosis (OSF) mostly focused on the activation of fibroblasts and collagen metabolism, while little involved in the epithelium. As we have reported the role of differentiated embryo chondrocyte expressed gene 1 (DEC1) in oral cancer and other precancerous lesions, this research aimed to explore its role in the OSF epithelium.

METHODS

Expression of DEC1 and other proteins were investigated in tissue array constructed with 33 OSF and 14 normal oral mucosa (NOM) tissues. Human oral keratinocytes treated with arecoline and/or hypoxia were used to simulate OSF epithelium and detected for morphological and protein alterations. Inhibition of DEC1 was used to explore its mediating role. Finally, animal models of OSF constructed by locally arecoline injecting in buccal mucosa were used to verify our findings.

RESULTS

DEC1 overexpression could be detected in the epithelium of OSF compared with that in NOM followed by phosphorylated FAK and Akt, and DEC1 showed a significant positive correlation with them. Cytology experiment revealed that OSF-like treatment could upregulate DEC1 expression followed by phosphorylated FAK, Akt, but inhibit E-cadherin, while knockdown of DEC1 could suppress the effects. Additionally, OSF mice revealed higher expression of DEC1 in the epithelium of buccal mucosa, along with synchronized alterations of phosphorylated FAK and Akt.

CONCLUSION

In the epithelium of OSF, overexpression of DEC1 induced activation of FAK/Akt signal axis, caused mesenchymal transition in epithelial cells, and may promote malignant transformation of OSF. Targeting DEC1 in OSF could be promising a new target for the diagnosis and treatment of this process.

Prognostic value of PD-1, PD-L1 and PD-L2 deserves attention in head and neck cancer

Head and neck cancer has high heterogeneity with poor prognosis, and emerging researches have been focusing on the prognostic markers of head and neck cancer. PD-L1 expression is an important basis for strategies of immunosuppressive treatment, but whether it has prognostic value is still controversial. Although meta-analysis on PD-L1 expression versus head and neck cancer prognosis has been performed, the conclusions are controversial. Since PD-L1 and PD-L2 are two receptors for PD-1, here we summarize and analyze the different prognostic values of PD-1, PD-L1, and PD-L2 in head and neck cancer in the context of different cell types, tissue localization and protein forms. We propose that for head and neck cancer, the risk warning value of PD-1/PD-L1 expression in precancerous lesions is worthy of attention, and the prognostic value of PD-L1 expression at different subcellular levels as well as the judgment convenience of prognostic value of PD-1, PD-L1, PD-L2 should be fully considered. The PD-L1 evaluation systems established based on immune checkpoint inhibitors (ICIs) are not fully suitable for the evaluation of PD-L1 prognosis in head and neck cancer. It is necessary to establish a new PD-L1 evaluation system based on the prognosis for further explorations. The prognostic value of PD-L1, PD-L2 expression in head and neck cancer may be different for early-stage and late-stage samples, and further stratification is required.

PD-L1 in oral squamous cell carcinoma: A key biomarker from the laboratory to the bedside

Objectives and background: Oral squamous cell carcinoma (OSCC) is a highly malignant disease with an increasing incidence. The need to improve therapeutic strategies for patients affected by OSCC is an urgent challenge. Currently, the advent of immunotherapy represents an important step toward this aim. Programmed cell death‐ligand 1 (PD‐L1), a membrane protein that can be expressed on tumor and inflammatory cells is a key biomarker whose expression is determined by means of immunohistochemistry and is necessary for selecting patients for immunotherapy. Methods: In this study, we review the methods of PD‐L1 assessment and outcomes achieved with immunotherapy in the treatment of OSCC patients. Results: Based on a meta‐analysis we demonstrate a lack of prognostic significance of PD‐L1 in OSCC. Conclusions: We also highlight unresolved issues including difficulties in standardizing PD‐L1 evaluation and discuss future opportunities such as leveraging digital pathology.

Skewed Th17/Treg balance during progression and malignant transformation of oral submucous fibrosis

OBJECTIVES

The aim of our study was to determine the impact of Th17/Treg imbalance on the progression and malignant transformation of oral submucosal fibrosis (OSF).

MATERIALS AND METHODS

To assess Th17 and Treg expression, overall 52 peripheral blood samples from OSF, oral squamous cell carcinoma (OSCC) patients, and healthy donors were analyzed by flow cytometry. Thirty normal oral mucosa, 72 OSF, and 90 OSCC samples were analyzed by immunohistochemistry.

RESULTS

In peripheral blood samples, in OSCC with OSF, Th17 and Treg expression were significantly higher than those in OSF and OSCC without OSF as confirmed by immunohistochemistry. During OSF progression, Th17 and Th17/Treg ratio showed an increasing trend, while Treg expression showed a decreasing trend. Treg expression was significantly higher in OSCC with OSF than in OSF and OSCC without OSF, whereas the Th17/Treg ratio was significantly lower in OSCC with OSF. Treg expression was significantly correlated with smoking and clinical stage. Th17/Treg ratio was significantly associated with tumor size, lymph node metastasis, and clinical stage. A low Th17/Treg ratio was significantly associated with poor prognosis.

CONCLUSIONS

Th17/Treg ratio is a potential diagnostic indicator for OSF occurrence and malignant transformation and was an independent prognostic factor for OSCC.