Head and neck squamous cell carcinoma (HNSCC) frequently develops in the oral and upper aerodigestive regions following chronic exposure to mutagenic factors such as tobacco, alcohol, and betel nut.

Alterations in the tumour suppressor genes TP53 and CDKN2A are among the most common genetic changes in HNSCC and often occur together in the same tumour.

However, the consequences of these combined alterations during the early stages of oral carcinogenesis remain poorly understood.

To better understand this, a research team comprising Ph.D. student Zichao Lu, Associate Professor Yasuhiro Mouri, and Professor Yasusei Kudo from the Department of Oral Bioscience, Tokushima University Graduate School of Biomedical Sciences, Japan, and the Institute of Photonics Human Health Frontier, Tokushima University, investigated how different combinations of TP53 and CDKN2A alterations influence oral carcinogenesis and the surrounding immune microenvironment.

Their findings were made available online and published in Volume 45 of the journal Oncogene on October 20, 2026.

The researchers were motivated by limitations in conventional mouse models of oral cancer.

Although TP53 and CDKN2A are frequently altered together in human HNSCC, conventional mouse models in which both genes are completely inactivated have not adequately reproduced oral carcinogenesis.

Moreover, the functions of these genes are not always completely lost in human tumours, as partial activity may remain depending on the type and combination of mutations.

The team therefore aimed to develop a model that more closely reflects these genetic conditions in human HNSCC.

The team generated mice carrying a human-relevant CDKN2A R80X truncating mutation and combined it with a loss-of-function alteration in Trp53, the mouse counterpart of TP53.

The mice were then exposed to 4-nitroquinoline-1-oxide, a carcinogen widely used to model oral cancer development.

This experimental system allowed the team to examine how specific combinations of tumour suppressor alterations affect the oral epithelium under carcinogenic stress.

The results revealed a distinct immune response during the early stages of carcinogenesis.

Mice carrying the relevant combination of Trp53 and Cdkn2a alterations showed activation of the cGAS–STING–NF-κB axis, accompanied by increased expression of inflammatory cytokines, chemokines, and interferon-stimulated genes.

Together, these changes indicated that the altered tumour-suppressor signalling was linked to activation of innate immune responses in the oral epithelium.

The immune response was also reflected in the cellular environment surrounding the developing lesions.

The researchers observed increased infiltration of T cells and natural killer cells, with a higher ratio of cytotoxic T cells to regulatory T cells.

Chemokines including Ccl3, Ccl4, and Ccl20 were elevated, further supporting the recruitment of cytotoxic immune cells.

The authors explain, “Our study reveals that the combination of genetic alterations in TP53 and CDKN2A can shape the immune microenvironment during the early stages of oral carcinogenesis.”

This immune activation was associated with delayed progression to invasive oral cancer.

In addition, treatment with the STING inhibitor H-151 reduced interferon-related gene expression and decreased the infiltration of certain T-cell populations, providing functional evidence that STING signalling contributes to the observed immune response

“Tumour-suppressor alterations do not simply promote cancer development; specific combinations of these alterations can also activate antitumor immunity during early carcinogenesis,” the authors state.

The immune landscape changed as the tumours progressed.

As lesions developed into squamous cell carcinoma, T-cell infiltration generally decreased across genotypes, consistent with the emergence of a more immunosuppressive tumour microenvironment.

The findings therefore suggest that the immune activation associated with specific TP53 and CDKN2A combinations may be a feature of early carcinogenesis that changes as malignancy develops.

To examine whether these genetic interactions were also associated with clinical outcomes in humans, the researchers analysed data from The Cancer Genome Atlas HNSC cohort.

Combined TP53/CDKN2A alteration patterns significantly separated overall survival and were associated with distinct survival patterns.

However, immune-activation signatures observed in the early mouse model were not clearly detected in the predominantly advanced-stage human tumours analysed, potentially reflecting the later stage of disease represented in these samples.

Looking ahead, the findings could have implications for assessing oral potentially malignant lesions.

Combining TP53 and CDKN2A genetic status with the immune status of oral lesions may eventually help assess progression risk and identify patients who require closer surveillance or earlier intervention.

The findings may also provide a basis for investigating approaches targeting the cGAS–STING pathway or immune checkpoints according to the genetic and immune characteristics of individual tumours.

However, further studies are needed to determine the optimal timing and clinical effectiveness of these approaches in humans.

“Ultimately, this knowledge may contribute to more precise risk assessment of oral precancerous lesions and to personalised prevention and treatment strategies based on both genetic alterations and the tumour immune microenvironment,” the authors conclude.

Together, the findings provide a new framework for understanding tumour-suppressor alterations not simply as functional or non-functional, but as specific combinations of changes that can influence immune responses during the earliest stages of oral cancer development.

Source: Tokushima University