Differential gene expression profile in Porphyromonas gingivalis treated human gingival keratinocytes and their role in the development of HNSCC

Abstract

Background: Periodontitis is considered to be one of the major risk factors associated with cancers of the oral cavity. Periodontogenic pathogens such as Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans are the important pathogens associated with periodontitis. Chronic exposure to bacterial components induces changes in the nearby cells. Hence, the present study has been designed to identify the molecular mechanisms that could be associated with the two disease conditions viz., periodontitis and head and neck cancer.

Objective: The present study investigated the differential gene expression profile in human gingival keratinocytes treated with P. gingivalis (Pg), a bacterium associated with periodontal disease, and its possible association with the development of Head and Neck Squamous Cell Carcinoma (HNSCC).

Methods: The study followed a computational design. Multiple tools and databases, such as GEOmnibus, STRING, Metascape, PANTHER, and UALCAN, cBioportal, were used to derive an association between gene expression during infection with P. gingivalis, and the resulting gene expression profiles were analyzed in the HNSCC dataset.

Results: The study revealed 29 genes from a pool of transcripts acquired after comparing the Pg-HIGK and Sham-HIGK. Among them, 3 genes i.e., FST, VRK3, and SGK1, were found to be overexpressed and significantly influenced patient survival. The upregulation of FST was found to correlate with poor prognosis in HNSCC patients.

Conclusion: The study provided insights into the possible association of FST, VRK3 and SGK1 in the development of HNSCC. Further investigations are warranted to confirm the functional role of these genes in establishing the cancer phenotype in patients with chronic infection with Pg.

Keywords: Carcinoma; Diagnosis; Genotoxic; Head and neck cancer; Microbiome; Prognosis.

Graphical abstract

Fig. 1

Volcano plot demonstrating differentially expressed genes (DEGs) that are upregulated (red) and downregulated (blue) in treated human immortalized gingival keratinocytes (HIGK). A p-value less than 0.05 is considered significant.

Fig. 2

Gene ontology analysis using Panther (http://www.pantherdb.org/) revealed the molecular pathways associated with the differentially expressed genes. ∗ 16 genes were clustered into the unclassified group.

Fig. 3

a) The protein-protein interaction network derived from STRING version 12.0 demonstrates protein clusters interacting with each other and independent proteins showing no interactions in the network; b) DisGENET analysis demonstrates the association of DEGs with different types of carcinomas, including carcinoma of the breast and mammary neoplasms.

Fig. 4

(a) Histogram demonstrating the gene expression in HIGK cells infected with Pg. A significant fold change of 1.89 (p-value = 0.026) was observed, (b) Box-Whisker plot showing the gene expression profile of the FST gene in HNSCC datasets. The gene expression between the normal and the HNSCC primary tumor group demonstrated significant upregulation in transcript levels (p-value = 1.624 × 10⁻¹²), (c) Kaplan Meier plot demonstrating survival probability of HNSCC patients with a differential expression profile. A statistically significant change in survival was observed with the expression of FST (p-value = 0.0026). The patients with increased expression of FST presented with poor prognosis.

Fig. 5

(a) Histogram demonstrating the VRK3 expression of the gene in HIGK cells infected with Pg, A significant fold change of 2.37 (p-value = 0.04) was observed, (b) Box-Whisker plot showing the gene expression profile of the VRK3 gene in HNSCC datasets. The gene expression between the normal and the HNSCC primary tumor group demonstrated significant upregulation in transcript levels (p-value = 4.380 × 10⁻⁶), (c) Kaplan Meier plot demonstrating survival probability of HNSCC patients with a differential expression profile. A statistically significant change in survival was observed with the expression of VRK3 (p-value = 0.00098). The patients with low/medium expression of VRK3 presented with poor prognosis.

Fig. 6

(a) Histogram demonstrating the SGK1 gene expression in HIGK cells infected with Pg, A significant fold change of 1.42 (p-value = 0.04) was observed, (b) Box-Whisker plot showing the gene expression profile of the SGK1 gene in HNSCC datasets. The gene expression between the normal and the HNSCC primary tumor group demonstrated significant upregulation in transcript levels (p-value = 9.099 × 10⁻³), (c) Kaplan Meier plot demonstrating survival probability of HNSCC patients with a differential expression profile. A statistically significant change in survival was observed with the expression of SGK1 (p-value = 0.056). The patients with low/medium expression of SGK1 presented with poor prognosis.

Fig. 7

Mutation profiling of the genes FST, VRK3, and SGK1 showing gross chromosomal abnormalities and point mutations.