Current Understanding of the HIF-1-Dependent Metabolism in Oral Squamous Cell Carcinoma

Hypoxia-inducible factor-1α at the invasive tumor front in oral squamous cell carcinoma

BACKGROUND

Hypoxia in oral cancer promotes tumoral invasion by inducing epithelial-mesenchymal transition, leading to aggressive tumor progression.

AIM

To characterize the expression of hypoxia-inducible factor 1-alpha (HIF-1α) at the invasive tumor front (ITF) in comparison to tumor islands (TI) in oral squamous cell carcinoma (OSCC) and to explore its relationship with E-cadherin and Vimentin expression.

METHODS

Thirty-eight cases of OSCC and five cases of normal oral mucosa (NOM) were included in this study. The ITF was identified based on the region and immune expression of AE1/AE3. Immunohistochemistry was performed to assess the expression of HIF-1α, Vimentin, and E-cadherin. The immunostaining was analyzed using an immunoreactive score, and the results were illustrated using immunofluorescence.

RESULTS

HIF-1α expression was significantly higher in the TI region compared to the ITF region (P = 0.0134). Additionally, a significant difference was observed between TI and NOM (P = 0.0115). In the ITF regions, HIF-1α expression showed a significant correlation with Vimentin expression, with higher levels of HIF-1α associated with increased Vimentin expression (P = 0.017).

CONCLUSION

Based on the results of this study, HIF-1α appears to play a distinct role in OSCC tumor progression, underscoring the importance of exploring hypoxia-driven changes in cellular phenotype at the ITF of OSCC. Further research is needed to better understand their impact on OSCC prognosis.

Exogenous BMI1 expression aggravates oral squamous cell carcinomas in tongue epithelia

Oral squamous cell carcinoma (OSCC) is characterized by aggressiveness and a poor prognosis, in part because most patients are diagnosed during the later stages of the disease. B cell-specific Moloney murine leukemia virus integration site 1 (BMI1), part of polycomb repressive complex 1 (PRC1), is a key transcription factor overexpressed in OSCC. Although increased BMI1 has been linked to tumor formation in mouse models of the disease, the molecular mechanisms have not been elucidated. Here we used a transgenic mouse line (KrTB) that selectively overexpresses BMI1 in the tongue basal epithelial stem cells (SCs) to delineate BMI1 actions during oral tumorigenesis. By tumor pathological classification after 4-nitroquinoline 1-oxide (4-NQO)-induced carcinogenesis we detected more severe tumors in mice with ectopic BMI1 expression. Genome-wide transcriptomics indicated that mRNAs associated with human OSCC, including SOX9, HIF1A, MMP9, INHBB, and MYOF, were further increased by ectopic BMI1 expression in murine tongue epithelia. mRNAs encoding multiple metabolic targets, such as SLC2A1 (GLUT1), PKM, LDHA, and HK2, were also increased upon BMI1 overexpression in 4-NQO-treated tongue epithelia. Furthermore, we detected BMI1, SOX9, and GLUT1 proteins in the infiltrating cells of invasion fronts identified by markers of invasive SCCs. Finally, metabolomic data show that BMI1 overexpression in tongue epithelia promotes glycolysis during 4-NQO-induced carcinogenesis. Thus, our data demonstrate that BMI1 causes OSCC cells to alter cell metabolism, as changes in many of these transcripts are linked to increased glycolysis and metabolic reprograming that occurs during carcinogenesis.

Hypoxia signaling in cancer: HIF-1α stimulated by COVID-19 can lead to cancer progression and chemo-resistance in oral squamous cell carcinoma (OSCC)

The potential implications of Coronavirus disease-2019 (COVID-19) on oral squamous cell carcinoma (OSCC) development, chemo-resistance, tumor recurrence, and patient outcomes are explored, emphasizing the urgent need for tailored therapeutic strategies to mitigate these risks. The role of hypoxia-inducible factor 1-alpha (HIF-1α) in OSCC studies has highlighted HIF-1α as a crucial prognostic marker in OSCC, with implications for disease prognosis and patient survival. Its overexpression has been linked to aggressive subtypes in early OSCC stages, indicating its significance as an early biomarker for disease progression. Moreover, dysplastic lesions with heightened HIF-1α expression exhibit a greater propensity for malignant transformation, underscoring its role in early oral carcinogenesis. Cancer patients, including those with OSCC, face an elevated risk of severe COVID-19 complications, which may further impact cancer progression and treatment outcomes. Understanding the interplay between COVID-19 infection, HIF-1α activation, and OSCC pathogenesis is crucial for enhancing clinical management strategies. So, insights from this review shed light on the significance of HIF-1α in OSCC tumorigenesis, metastasis formation, and patient prognosis. The review underscores the need for further research to elucidate the precise mechanisms through which HIF-1α modulates cancer progression and chemo-resistance in the context of COVID-19 infection. Such knowledge is essential for developing targeted therapeutic interventions to improve outcomes for OSCC patients.

Tumor microenvironment in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly aggressive and malignant tumor of oral cavity with a poor prognosis and high mortality due to the limitations of existing therapies. The significant role of tumor microenvironment (TME) in the initiation, development, and progression of OSCC has been widely recognized. Various cells in TME, including tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), T lymphocytes, tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs) and dendritic cells (DCs), form a complicated and important cellular network to modulate OSCC proliferation, invasion, migration, and angiogenesis by secreting RNAs, proteins, cytokines, and metabolites. Understanding the interactions among cells in TME provides the foundation for advanced clinical diagnosis and therapies. This review summarizes the current literature that describes the role of various cellular components and other TME factors in the progression of OSCC, hoping to provide new ideas for the novel OSCC treatment strategies targeting the complicated cellular network and factors that mediate the interactive loops among cells in TME.

SLC2A3 promotes head and neck squamous cancer developing through negatively regulating CD8+ T cell in tumor microenvironment

Recent studies have identified SLC2A3 as being abnormally upregulated in multiple tumor types, correlating with poor survival and disrupted microenvironments. However, its prognostic significance in head and neck squamous cell carcinoma (HNSC) remains underexplored. In this study, SLC2A3 was screened as a potential risk gene influencing both immune and tumor components within the tumor microenvironment (TME) of 504 HNSC patients from the TCGA database. Immune infiltration analyses and clinical significance on SLC2A3 were conducted using ESTIMATE, CIBERSORT, ssGSEA, TIMER and clinical prognosis parameters. Additionally, the single-cell dataset is used to analyze the expression of SLC2A3 in various subpopulations. The magnetic activated cell sorting (MACS) is used to isolate CD8+ T cells from PBMCs or tumor tissues. Flow cytometry is used to identify purified and activated CD8+ T cells. GSEA and WB were used to investigate the molecular mechanism of SLC2A3 in CD8+ T cells. The co-culture system of CD8+ T cells and TU686 was used to investigate the effects of SLC2A3 on immune cells and tumor development. In this study, SLC2A3 was identified as a potential risk gene affecting both immune cells and tumor components within the TME of 504 HNSC patients derived from the TCGA database. We conducted immune infiltration analyses and assessed the clinical significance of SLC2A3 using various bioinformatics tools, including ESTIMATE, CIBERSORT, ssGSEA, and TIMER, along with clinical prognosis parameters. The single-cell RNA sequencing dataset was utilized to examine SLC2A3 expression across different cellular subpopulations. Magnetic activated cell sorting (MACS) was employed to isolate CD8+ T cells from peripheral blood mononuclear cells (PBMCs) or tumor tissues. Flow cytometry was implemented to confirm the purity and activation state of the isolated CD8+ T cells. GSEA and Western blot were applied to explore the molecular mechanisms underlying SLC2A3's role in CD8+ T cells. Lastly, a co-culture system involving CD8+ T cells and TU686 tumor cells was established to study the impact of SLC2A3 on immune cell function and tumor progression. SLC2A3 emerges as an actively variable gene within the immune and stromal components of the TME, linked to aggravated immune infiltration and poor clinical outcomes. The upregulated expression of SLC2A3 is predominantly enriched in immune-related biological processes and linked to the suppression of CD8+ T cells, which are crucial for the survival of HNSC patients. Furthermore, SLC2A3 exhibits specific overexpression in CD8+ T cells and may potentially trigger ferroptosis. Knockdown of SLC2A3 led to a significant increase in the proliferation of CD8+ T cells compared to those without knockdown. In co-culture systems, CD8+ T cells with SLC2A3 knockdown demonstrated an enhanced ability to eliminate tumor cells compared to those without the knockdown. SLC2A3 is associated with changes in the TME and prognostic indicators. Moreover, high SLC2A3 expression in CD8+ T cells may drive cell death through ferroptosis, fostering tumor progression.

Prognostic implications of HIF-1α expression in anal squamous cell carcinoma treated with intensity-modulated radiotherapy (IMRT)

Background

Hypoxia-inducible factor-1α (HIF-1α) is a crucial transcription factor activated under hypoxic conditions, known to regulate genes associated with tumor survival, progression, and response to therapy. This study aimed to evaluate the prognostic significance of HIF-1α expression in patients with anal squamous cell carcinoma (ASCC) undergoing chemoradiation therapy.

Methods

We conducted a retrospective analysis of 28 ASCC patients treated with intensity-modulated radiotherapy (IMRT) at our center from 2009 to 2022. HIF-1α expression was assessed via immunohistochemistry on formalin-fixed paraffin-embedded tissue specimens. Quantitative analysis of HIF-1α expression was performed, and its relationship with clinical outcomes, including disease-free survival (DFS), locoregional relapse-free survival (LRRFS), and overall survival (OS), was examined using Cox regression models. Furthermore, ASCC tissue specimens from 17 patients were analyzed for potential PIK3CA mutations using Sanger sequencing.

Results

High HIF-1α expression was significantly associated with poorer DFS (p = 0.005), LRRFS (p = 0.012), and OS (p = 0.009). HIF1α expression was marginally significantly higher in males compared to females (p = 0.056) while there was no significant difference found based on tumor stage or p16 status. However, a positive correlation was identified between BMI and HIF-1α levels (Pearson correlation r = 0.5, p = 0.0084), suggesting a link between metabolic status and tumor hypoxia. Only one patient exhibited a PIK3CA mutation, preventing a reliable assessment of its correlation with HIF-1α expression.

Conclusion

Our findings underscore the importance of HIF-1α as a potential biomarker for predicting survival outcomes in ASCC patients treated with chemoradiation. The association between higher BMI and increased HIF-1α expression may provide insights into the interplay between metabolic health and tumor biology in ASCC. Further studies with larger cohorts are needed to validate these findings and explore targeted therapies focusing on HIF-1α modulation.

Application of metabolomics in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a prevalent malignancy affecting the head and neck region. The prognosis for OSCC patients remains unfavorable due to the absence of precise and efficient early diagnostic techniques. Metabolomics offers a promising approach for identifying distinct metabolites, thereby facilitating early detection and treatment of OSCC.

OBJECTIVE

This review aims to provide a comprehensive overview of recent advancements in metabolic marker identification for early OSCC diagnosis. Additionally, the clinical significance and potential applications of metabolic markers for the management of OSCC are discussed.

RESULTS

This review summarizes metabolic changes during the occurrence and development of oral squamous cell carcinoma and reviews prospects for the clinical application of characteristic, differential metabolites in saliva, serum, and OSCC tissue. In this review, the application of metabolomic technology in OSCC research was summarized, and future research directions were proposed.

CONCLUSION

Metabolomics, detection technology that is the closest to phenotype, can efficiently identify differential metabolites. Combined with statistical data analyses and artificial intelligence technology, it can rapidly screen characteristic biomarkers for early diagnosis, treatment, and prognosis evaluations.

The transcription factor BMI1 increases hypoxic signaling in oral cavity epithelia

The tongue epithelium is maintained by a proliferative basal layer. This layer contains long-lived stem cells (SCs), which produce progeny cells that move up to the surface as they differentiate. B-lymphoma Mo-MLV insertion region 1 (BMI1), a protein in mammalian Polycomb Repressive Complex 1 (PRC1) and a biomarker of oral squamous cell carcinoma, is expressed in almost all basal epithelial SCs of the tongue, and single, Bmi1-labelled SCs give rise to cells in all epithelial layers. We previously developed a transgenic mouse model (KrTB) containing a doxycycline- (dox) controlled, Tet-responsive element system to selectively overexpress Bmi1 in the tongue basal epithelial SCs. Here, we used this model to assess BMI1 actions in tongue epithelia. Genome-wide transcriptomics revealed increased levels of transcripts involved in the cellular response to hypoxia in Bmi1-overexpressing (KrTB+DOX) oral epithelia even though these mice were not subjected to hypoxia conditions. Ectopic Bmi1 expression in tongue epithelia increased the levels of hypoxia inducible factor-1 alpha (HIF1α) and HIF1α targets linked to metabolic reprogramming during hypoxia. We used chromatin immunoprecipitation (ChIP) to demonstrate that Bmi1 associates with the promoters of HIF1A and HIF1A-activator RELA (p65) in tongue epithelia. We also detected increased SC proliferation and oxidative stress in Bmi1-overexpressing tongue epithelia. Finally, using a human oral keratinocyte line (OKF6-TERT1R), we showed that ectopic BMI1 overexpression decreases the oxygen consumption rate while increasing the extracellular acidification rate, indicative of elevated glycolysis. Thus, our data demonstrate that high BMI1 expression drives hypoxic signaling, including metabolic reprogramming, in normal oral cavity epithelia.

Neoadjuvant Radiochemotherapy Alters the Immune and Metabolic Microenvironment in Oral Cancer-Analyses of CD68, CD163, TGF-β1, GLUT-1 and HIF-1α Expressions

BACKGROUND

The first-line treatment of oral squamous cell carcinoma (OSCC) involves surgical tumor resection, followed by adjuvant radio(chemo)therapy (R(C)T) in advanced cases. Neoadjuvant radio- and/or chemotherapy has failed to show improved survival in OSCC. Recently, neoadjuvant immunotherapy has shown promising therapeutic efficacy in phase 2 trials. In this context, the addition of radio- and chemotherapy is being reconsidered. Therefore, a better understanding of the tumor-biologic effects of neoadjuvant RCT would be beneficial. The current study was conducted on a retrospective cohort of patients who received neoadjuvant RCT for the treatment of oral cancer. The aim of the study was to evaluate the influence of neoadjuvant RCT on the immunological tumor microenvironment (TME) and hypoxic and glucose metabolisms.

METHODS

A cohort of 45 OSSC tissue samples from patients were analyzed before and after RCT (total 50.4 Gy; 1.8 Gy 5× weekly; Cisplatin + 5-Fluorouracil). Immunohistochemistry for CD68, CD163, TGF-β, GLUT-1 and HIF-1α was performed using tissue microarrays and automated cell counting. Differences in expression before and after RCT and associations with histomorphological parameters (T-status, N-status) were assessed using the Mann-Whitney U test.

RESULTS

Tumor resection specimens after neoadjuvant RCT showed a significant decrease in CD68 infiltration and a significant increase in CD163 cell density. The CD68/CD163 ratio was significantly lower after RCT, indicating a shift toward M2 polarization. The GLUT-1 and HIF-1α expressions were significantly lower after RCT. Larger tumors (T3/T4) showed a lower GLUT-1 expression. Other biomarkers were not associated with the T- and N-status.

CONCLUSIONS

Neoadjuvant RCT with 50.4 Gy induced a shift toward the M2 polarization of macrophages in the TME. This change in immune composition is not favorable and may be prognostically negative and counteract immunotherapeutic approaches. In addition, the decreased expressions in GLUT-1 and HIF-1α indicate reductions in the glucose metabolism and hypoxic energy metabolism in response to "high dose" neoadjuvant RCT, which may be therapeutically desirable.

Oral tumor heterogeneity, its implications for patient monitoring and designing anti-cancer strategies

Oral cancer tumors occur in the mouth and are mainly derived from oral mucosa linings. It is one of the most common and fatal malignant diseases worldwide. The intratumor heterogeneity (ITH) of oral cancerous tumor is vast, so it is challenging to study and interpret. Due to environmental selection pressures, ITH arises through diverse genetic, epigenetic, and metabolic alterations. The ITH also talks about peri-tumoral vascular/ lymphatic growth, perineural permeation, tumor necrosis, invasion, and clonal expansion/ the coexistence of multiple subclones in a single tumor. The heterogeneity offers tumors the adaptability to survive, induce growth/ metastasis, and, most importantly, escape antitumor therapy. Unfortunately, the ITH is prioritized less in determining disease pathology than the traditional TNM classifications or tumor grade. Understanding ITH is challenging, but with the advancement of technology, this ITH can be decoded. Tumor genomics, proteomics, metabolomics, and other modern analyses can provide vast information. This information in clinics can assist in understanding a tumor's severity and be used for diagnostic, prognostic, and therapeutic decision-making. Lastly, the oral tumor ITH can lead to individualized, targeted therapy strategies fighting against OC.

Targeting oral tumor microenvironment for effective therapy

Oral cancers are among the common head and neck malignancies. Different anticancer therapy modalities such as chemotherapy, immunotherapy, radiation therapy, and also targeted molecular therapy may be prescribed for targeting oral malignancies. Traditionally, it has been assumed that targeting malignant cells alone by anticancer modalities such as chemotherapy and radiotherapy suppresses tumor growth. In the last decade, a large number of experiments have confirmed the pivotal role of other cells and secreted molecules in the tumor microenvironment (TME) on tumor progression. Extracellular matrix and immunosuppressive cells such as tumor-associated macrophages, myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts (CAFs), and regulatory T cells (Tregs) play key roles in the progression of tumors like oral cancers and resistance to therapy. On the other hand, infiltrated CD4 + and CD8 + T lymphocytes, and natural killer (NK) cells are key anti-tumor cells that suppress the proliferation of malignant cells. Modulation of extracellular matrix and immunosuppressive cells, and also stimulation of anticancer immunity have been suggested to treat oral malignancies more effectively. Furthermore, the administration of some adjuvants or combination therapy modalities may suppress oral malignancies more effectively. In this review, we discuss various interactions between oral cancer cells and TME. Furthermore, we also review the basic mechanisms within oral TME that may cause resistance to therapy. Potential targets and approaches for overcoming the resistance of oral cancers to various anticancer modalities will also be reviewed. The findings for targeting cells and potential therapeutic targets in clinical studies will also be reviewed.

Overexpression of Hypoxia-Inducible Factor-1α and Its Relation with Aggressiveness and Grade of Oral Squamous Cell Carcinoma

Hypoxia-inducible factor-1α (HIF-1α) has been shown to be involved in cancer metastasis in several cancer types. There is however conflicting evidence of HIF-1α expression with oral cancer prognosis. Therefore, this study set out to investigate HIF-1α overexpression and its relationship with the aggressiveness and grade of oral squamous cell carcinoma (OSCC) and to explore the diagnostic potential of HIF-1α overexpression in OSCC in a cohort of Pakistani patients. Immunostaining of HIF-1α was performed on 54 OSCC and 14 normal oral mucosa (NOM) tissue samples and various cut-offs were used to evaluate its immunohistochemical expression. HIF-1α expression in OSCC samples was significantly higher than in controls, with minimal immunoreactivity in NOM. HIF-1α overexpression was significantly associated with increased tumor size (p = 0.046). However, no association was found between HIF-1α overexpression and increasing Broder's histological grade or TNM stage. The cut-off >10% cells with moderate to marked intensity carried a sensitivity of 70% and a specificity of 100% to distinguish between tumor and control. ROC curve analysis of HIF-1α weighted histoscores showedHIF-1α overexpression as a highly sensitive and specific diagnostic test (p < 0.001, AUC = 0.833). HIF-1α overexpression is a tumor-specific finding associated with increased tumor size and carries a potential diagnostic role.

PFC@O2 Targets HIF-1α to Reverse the Immunosuppressive TME in OSCC

As a typical hallmark of solid tumors, hypoxia affects the effects of tumor radiotherapy, chemotherapy, and photodynamic therapy. Therefore, targeting the hypoxic tumor microenvironment (TME) is a promising treatment strategy for cancer therapy. Here, we prepared an Albumin Human Serum (HSA)-coated perfluorocarbon (PFC) carrying oxygen (PFC@O₂) to minimize OSCC hypoxia. The results showed that PFC@O₂ significantly downregulated the expression of HIF-1α and the number of M2-like macrophages in vitro. Furthermore, PFC@O₂ effectively inhibited the growth of oral squamous cell carcinoma (OSCC) and reduced the proportion of negative immunoregulatory cells, including myeloid-derived suppressor cells (MDSCs) and M2-like macrophages of TME in a 4-nitroquinoline N-oxide (4NQO)-induced mouse model. Conversely, the infiltration of CD4⁺ and CD8⁺ T cells was significantly increased in TME, suggesting that the anti-tumor immune response was enhanced. However, we also found that hypoxia-relative genes expression was positively correlated with CD68⁺/CD163⁺ TAMs in human tissue specimens. In summary, PFC@O₂ could effectively inhibit the progression of OSCC by alleviating hypoxia, which provides a practical basis for gas therapy and gas synergistic therapy for OSCC.

RNA N6-Methyladenosine (m6A) Methyltransferase-like 3 Facilitates Tumorigenesis and Cisplatin Resistance of Arecoline-Exposed Oral Carcinoma

BACKGROUND

Arecoline is known as the main active carcinogen found in areca nut extract that drives the pathological progression of oral squamous cell carcinoma (OSCC). Studies have revealed that dysregulation of RNA N6-methyladenosine (m6A) methyltransferase components is intimately linked to cancer initiation and progression, including oral cancer.

METHODS

The arecoline-induced dysregulated methyltransferase-like 3 (METTL3) gene was identified using RNA-seq transcriptome assay. Using in vitro and in vivo models, the biological roles of METTL3 in arecoline-transformed oral cancer were examined.

RESULTS

We found that METTL3 was markedly elevated in arecoline-exposed OSCC cell lines and OSCC tissues of areca nut chewers. We identified that hypoxia-inducible factor 1-alpha (HIF-1α) stimulated METTL3 expression at the transcriptional level and further proved that METTL3-MYC-HIF-1α formed a positive autoregulation loop in arecoline-transformed OSCC cells. Subsequently, we manifested that METTL3 depletion profoundly reduced cell proliferation, cell migration, oncogenicity, and cisplatin resistance of arecoline-exposed OSCC cells.

CONCLUSIONS

Developing novel strategies to target METTL3 may be a potential way to treat OSCC patients, particularly those with areca nut chewing history and receiving cisplatin treatment.

Diagnosis of Oral Squamous Cell Carcinoma Using Deep Neural Networks and Binary Particle Swarm Optimization on Histopathological Images: An AIoMT Approach

Overall prediction of oral cavity squamous cell carcinoma (OCSCC) remains inadequate, as more than half of patients with oral cavity cancer are detected at later stages. It is generally accepted that the differential diagnosis of OCSCC is usually difficult and requires expertise and experience. Diagnosis from biopsy tissue is a complex process, and it is slow, costly, and prone to human error. To overcome these problems, a computer-aided diagnosis (CAD) approach was proposed in this work. A dataset comprising two categories, normal epithelium of the oral cavity (NEOR) and squamous cell carcinoma of the oral cavity (OSCC), was used. Feature extraction was performed from this dataset using four deep learning (DL) models (VGG16, AlexNet, ResNet50, and Inception V3) to realize artificial intelligence of medial things (AIoMT). Binary Particle Swarm Optimization (BPSO) was used to select the best features. The effects of Reinhard stain normalization on performance were also investigated. After the best features were extracted and selected, they were classified using the XGBoost. The best classification accuracy of 96.3% was obtained when using Inception V3 with BPSO. This approach significantly contributes to improving the diagnostic efficiency of OCSCC patients using histopathological images while reducing diagnostic costs.

Identification and validation of transcription factor-driven enhancers of genes related to lipid metabolism in metastatic oral squamous cell carcinomas

Background

The role and mechanisms of lipid metabolism in oral squamous cell carcinomas (OSCC) metastasis have not been clarified. This study aims to identify lipid metabolism-related genes and transcription factors regulated by metastasis-associated enhancers (MAEs) in OSCC.

Methods

Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) were performed for lipid metabolism enrichment. TCGA data were used to analyze the differentially expressed lipid metabolism-related genes. MAEs were analyzed using GSE120634. Overlapping analysis was used to screen the MAE-regulated lipid metabolism-related genes, and the prognosis of these genes was analyzed. Transcription factor prediction was performed for the MAE-regulated lipid metabolism-related genes with prognostic value. Validation of the metastatic specificity of MAEs at ACAT1, OXSM and VAPA locus was performed using GSE88976 and GSE120634. ChIP-qPCR, qRT-PCR and Western blotting were used to verify the regulation of ACAT1, OXSM and VAPA expression by CBFB. Effects of CBFB knockdown on proliferation, invasion and lipid synthesis in metastatic OSCC cells were analyzed.

Results

Lipid metabolism was significantly enhanced in metastatic OSCC compared to non-metastatic OSCC. The expression of 276 lipid metabolism-related genes was significantly upregulated in metastatic OSCC, which were functionally related to lipid uptake, triacylglycerols, phospholipids and sterols metabolism. A total of 6782 MAEs and 176 MAE-regulated lipid metabolism-related genes were filtered. Three MAE-regulated lipid metabolism-related genes, ACAT1, OXSM and VAPA, were associated with a poor prognosis in OSCC patients. Enhancers at ACAT1, OXSM and VAPA locus were metastasis-specific enhancers. CBFB regulated ACAT1, OXSM and VAPA expression by binding to the enhancers of these genes. Knockdown of CBFB inhibited proliferation, invasion and lipid synthesis in metastatic OSCC cells.

Conclusion

The MAE-regulated lipid metabolism-related genes (ACAT1, OXSM and VAPA) and the key transcription factor (CBFB) were identified. CBFB knockdown inhibited proliferation, invasion and lipid synthesis of OSCC cells. These findings provide novel candidates for the development of therapeutic targets for OSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02157-7.

Characterization of normal and cancer stem-like cell populations in murine lingual epithelial organoids using single-cell RNA sequencing

The advances in oral cancer research and therapies have not improved the prognosis of patients with tongue cancer. The poor treatment response of tongue cancer may be attributed to the presence of heterogeneous tumor cells exhibiting stem cell characteristics. Therefore, there is a need to develop effective molecular-targeted therapies based on the specific gene expression profiles of these cancer stem-like cell populations. In this study, the characteristics of normal and cancerous organoids, which are convenient tools for screening anti-cancer drugs, were analyzed comparatively. As organoids are generally generated by single progenitors, they enable the exclusion of normal cell contamination from the analyses. Single-cell RNA sequencing analysis revealed that p53 signaling activation and negative regulation of cell cycle were enriched characteristics in normal stem-like cells whereas hypoxia-related pathways, such as HIF-1 signaling and glycolysis, were upregulated in cancer stem-like cells. The findings of this study improved our understanding of the common features of heterogeneous cell populations with stem cell properties in tongue cancers, that are different from those of normal stem cell populations; this will enable the development of novel molecular-targeted therapies for tongue cancer.

Expression profiles of tRNA-derived small RNA and their potential roles in oral submucous fibrosis

BACKGROUND

Although transfer RNA (tRNA) has been found to be the main source of a rich class of noncoding RNA, the tRNA-derived small RNA (tsRNA) has been proved to play an irreplaceable role in the human body, and its dynamic imbalance could affect the progress of the disease. However, the research on tsRNA in oral submucous fibrosis (OSF) is still scarce.

METHODS

We sequenced the OSF and validated it by PCR. We found that there were significant differences in their expression levels in OSF. Furthermore, bioinformatic analysis was performed to explore the roles of these fragments in oral submucous fibrosis.

RESULTS

Of 126 tsRNAs in OSF were dysregulated, including 73 upregulated tsRNAs and 53 downregulated tsRNAs. The downregulated tiRNA-Val-CAC-002, tRF-Asn-GTT-005, tRF-Trp-CCA-007 and upregulated tRF-Gly-TCC-016, tRF-Pro-TGG-009 showed significant differences by qRT-PCR validation, which were consistent with the results of RNA sequencing. Gene ontology and pathway analysis revealed that tRF-Gly-TCC-016 would possibly promote the formation and progress of OSF through cytokine-cytokine receptor interaction and cAMP signal pathway, while tiRNA-Val-CAC-002 could be primarily concerned with the transition from OSF to oral squamous cell carcinoma (OSCC).

CONCLUSION

tRNA-derived fragments are dysregulated and could be involved in the pathogenesis of oral submucous fibrosis. tRF-Gly-TCC-016 and tiRNA-Val-CAC-002 may be new regulatory molecules that could affect the process of OSF by regulating signal pathways through interacting with multiple genes.

The integration of differentially expressed genes based on multiple microarray datasets for prediction of the prognosis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common human malignancy. However, its pathogenesis and prognostic information are poorly elucidated. In the present study, we aimed to probe the most significant differentially expressed genes (DEGs) and their prognostic performance in OSCC. Multiple microarray datasets from the Gene Expression Omnibus (GEO) database were aggregated to identify DEGs between OSCC tissue and control tissue. Least absolute shrinkage and selection operator (LASSO) Cox model was constructed to determine the prognostic performance of the aggregated DEGs based on The Cancer Genome Atlas (TCGA) OSCC cohort. Ten datasets with 341 OSCC samples and 283 control samples were included. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment revealed that the integrated DEGs were enriched in the IL-17 signaling pathway, viral protein interactions with cytokines and cytokine receptors, and amoebiasis, among others. Our LASSO Cox model was able to discriminate two groups with different overall survival in the training cohort and test cohort (p < 0.001). The time-dependent receiver operating characteristic (ROC) curve revealed that the area under the curve (AUC) values at one year, three years, and five years were 0.831, 0.898, and 0.887, respectively. In the testing cohort, the time-dependent ROC curve showed that the AUC values at one year, three years, and five years were 0.696, 0.693, and 0.860, respectively. Our study showed that the integrated DEGs of OSCC might be applicable in the evaluation of prognosis in OSCC. However, further research should be performed to validate our findings.

Silencing DNA Polymerase β Induces Aneuploidy as a Biomarker of Poor Prognosis in Oral Squamous Cell Cancer

Most patients with oral squamous cell cancer (OSCC) have a locally advanced stage at diagnosis. The treatment strategies are diverse, including surgery, radiotherapy and chemotherapy. Despite multimodality treatment, the response rate is unsatisfactory. DNA repair and genetic instability are highly associated with carcinogenesis and treatment outcomes in oral squamous cell cancer, affecting cell growth and proliferation. Therefore, focusing on DNA repair and genetic instability interactions could be a potential target for improving the outcomes of OSCC patients. DNA polymerase-β (POLB) is an important enzyme in base excision repair and contributes to gene instability, leading to tumorigenesis and cancer metastasis. The aim of our study was to confirm POLB regulates the growth of OSCC cells through modulation of cell cycle and chromosomal instability. We analyzed a tissue array from 133 OSCC patients and discovered that low POLB expression was associated with advanced tumor stage and poor overall survival. In multivariate Cox proportional hazards regression analysis, low POLB expression and advanced lymph node status were significantly associated with poor survival. By performing in vitro studies on model cell lines, we demonstrated that POLB silencing regulated cell cycles, exacerbated mitotic abnormalities and enhanced cell proliferation. After POLB depletion, OSCC cells showed chromosomal instability and aneuploidy. Thus, POLB is an important maintainer of karyotypic stability in OSCC cells.