CircRNAs: Roles in regulating head and neck squamous cell carcinoma

Prognostic and clinicopathological roles of circular RNA expression in chemoresistance in head and neck squamous cell carcinoma: a systematic review

Background

Characterized by a poor prognosis and survivability, head and neck squamous cell carcinoma (HNSCC) is an aggressive neoplastic condition with a propensity for recurrence where the development of chemoresistance adversely affects the prognostic outcome. Recently, it was shown that circular RNAs (circRNAs) augment the cellular survivability and chemoresistance of malignant cells. Hence, biomarkers for early detection of chemoresistance in these patients can significantly aid in preventing a poor prognostic outcome.

Objective

The present study aimed to systematically identify circRNAs that play a vital role in the development of chemoresistance in HNSCC and understand their mechanisms of action in HNSCC chemoresistance.

Methods

The protocol was prospectively registered on PROSPERO with protocol no. CRD42024532291. A six-stage methodological and PRISMA recommendations were followed for the review.

Results and Discussion

13 studies were identified which yielded 13 circRNAs which have been investigated for their role in the chemoresistance in HNSCC. Of these, 11 circRNAs were reported to be upregulated while only 2 circRNAs were found to be downregulated. Moreover, we found that circRNAs can modulate autophagy (circPARD3, circPKD2, circAP1M2 and circPGAM1), apoptosis (circ-ILF2, circANKS1B, circTPST2, circPUM1 and circ_0001971), drug efflux (circ-ILF2, has_circ_0005033 and circTPST2), EMT (circANKS1B, circCRIM1, circ_0001971), tumor microenvironment (circ-ILF2. circ-ILF2, circCRIM1 and circTPST2), DNA damage (circTPST2) and malignant potential (hsa_circ_0000190 and hg19_ circ_0005033).

Conclusion

The present study identified 13 circRNAs which may serve as biomarkers for prognosis as well as response to chemotherapy in HNSCC.

Systematic Review Registration

PROSPERO, identifier CRD42024532291.

CircCCT2/miR-146a-5p/IRAK1 axis promotes the development of head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC), a highly invasive malignancy with a poor prognosis, is one of the most common cancers globally. Circular RNAs (circRNAs) have become key regulators of human malignancies, but further studies are necessary to fully understand their functions and possible causes in HNSCC.

METHODS

CircCCT2 expression levels in HNSCC tissues and cells were measured via qPCR. CircCCT2 was characterized by Sanger sequencing, qRT-PCR, RNase R & Actinomycin D treatment, nucleoplasmic separation and FISH experiments. CCK-8 and colony formation assays were performed to determine cell proliferation, and Transwell assays were used to determine migration and invasion. A xenograft tumor model was used to study the influence of circCCT2 on HNSCC in vivo. Dual-luciferase gene reporter, RIP, western blotting, and rescue experiments, were used to explore target-binding relationships and regulatory mechanisms.

RESULTS

CircCCT2 was significantly upregulated in HNSCC tissues and cells. High circCCT2 levels were associated with advanced T stage, N stage, clinical stage and poor prognosis. Functionally, we verified that circCCT2 promotes HNSCC development in vitro and in vivo. Mechanistically, functioning as a competitive endogenous RNA (ceRNA) or miRNA sponge, circCCT2 binds directly to miR-146a-5p and increases interleukin-1 receptor-associated kinase 1 (IRAK1) levels, which enhances the malignant development of HNSCC by driving epithelial-mesenchymal transition (EMT).

CONCLUSION

CircCCT2 promotes HNSCC development through the miR-146a-5p/IRAK1 axis, revealing that circCCT2 is a potential biomarker and target for HNSCC.

Knockdown of Methylation-Related Gene MBD2 Blocks Cell Growth by Upregulating p21 Expression in Head and Neck Squamous Cell Carcinoma

BACKGROUND

Methyl-CpG-binding domain 2 (MBD2) attaches to methylated DNA, which mediates methylated gene transcription, leading to gene silencing and affecting tumor progression. The molecular mechanisms of MBD2 in head and neck squamous cell carcinoma (HNSCC) remain insufficiently characterized.

AIMS

This study sought to assess the clinical relevance of MBD2 expression in HNSCC, with a particular focus on elucidating its functional role in tumor progression and its regulatory influence on p21 expression and cellular proliferation.

METHODS

We analyzed the relationships between MBD2 expression, clinicopathological features, and survival outcomes in HNSCC patients using data from the UALCAN, TCGA, and cBioPortal databases. The functional role of MBD2 in HNSCC was further investigated through in vitro experiments. p21 expression was assessed using western blotting and qRT-PCR in TU212 and AMC-HN8 cells. These cells were treated with either shRNA targeting MBD2, 5-azacytidine (5-Aza), or a combination of shRNA MBD2 and 5-Aza. Additionally, cell proliferation and viability were measured in each treatment group.

RESULTS

MBD2 was found to be frequently overexpressed in HNSCC tissues, and its altered expression was significantly associated with reduced overall survival (OS) and disease-free survival (DFS). Both shRNA-mediated MBD2 knockdown and 5-Aza treatment increased p21 expression in HNSCC cells, exhibiting similar functions with additive effects. Furthermore, both treatments significantly inhibited cell proliferation and viability.

CONCLUSION

These results indicated that shRNA-mediated MBD2 knockdown suppresses HNSCC cell growth by upregulating p21 expression. In addition to its role as an oncogene, MBD2 may serve as a prognostic biomarker and therapeutic target for HNSCC patients.

The biomarkers for maintenance Cancer stem cell features can be applicable in precision medicine of head and neck squamous cell carcinoma

Cancer stem cells (CSCs) play a crucial role in tumor relapse, proliferation, invasion, and drug resistance in head and neck squamous cell carcinoma (HNSCC). This narrative review aims to synthesize data from articles published between 2019 and 2023 on biomarkers for detecting CSCs in HNSCC and changes in molecular pathways, genetics, epigenetics, and non-coding RNAs (ncRNAs) in CSCs relevant to precision medicine approaches in HNSCC management. The search encompassed 41 in vitro studies and 22 clinical studies. CSCs exhibit diverse molecular profiles and unique biomarker expression patterns, offering significant potential for HNSCC diagnosis, treatment, and prognosis, thereby enhancing patient survival. Their remarkable self-renewal ability and adaptability are closely linked to tumorigenicity development and maintenance. Assessing biomarkers before and after therapy can aid in identifying various cell types associated with cancer progression and relapse. Screening for CSCs, senescent tumor cells, and cells correlated with the senescence process post-treatment has proven highly beneficial. However, the clinical application of precision medicine in HNSCC management is hindered by the lack of specific and definitive CSC biomarkers. Furthermore, our limited understanding of CSC plasticity, governed by genomic, transcriptomic, and epigenomic alterations during tumorigenesis, as well as the bidirectional interaction of CSCs with the tumor microenvironment, underscores the need for further research. Well-designed studies involving large patient cohorts are, therefore, essential to establish a standardized protocol and address these unresolved queries.

Head and neck cancer treatment in the era of molecular medicine

Head and neck cancers are a heterogeneous group of highly aggressive tumors and collectively represent the sixth most common cancer worldwide. Most head and neck cancers are squamous cell carcinomas (HNSCCs). Current multimodal treatment concepts combine surgery, chemotherapy, irradiation, immunotherapy, and targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of HNSCC and revealed novel therapeutic targets and prognostic/predictive biomarkers. Notably, HNSCC is characterized by complex relations between stromal, epithelial, and immune cells within the tumor microenvironment (TME). The TME consists of different subsets of immune cells that infiltrate the tumors and interact with the tumor cells or with each other. Understanding multiple pivotal factors in HNSCC tumorigenesis and tumor progression may help define novel targets and develop more effective therapies for patients. This review provides a comprehensive overview of the latest advances in the molecular biology of HNSCC and their effects on clinical oncology; it is meant for a broad readership in the head and neck cancers field.