HIF-1a expression and differential effects on survival in patients with oral cavity, larynx, and oropharynx squamous cell carcinomas

Understanding Hypoxia-Driven Tumorigenesis: The Interplay of HIF1A, DNA Methylation, and Prolyl Hydroxylases in Head and Neck Squamous Cell Carcinoma

Hypoxia-inducible factor 1-alpha (HIF1A) is a key transcription factor aiding tumor cells' adaptation to hypoxia, regulated by the prolyl hydroxylase family (EGLN1-3) by directing toward degradation pathways. DNA methylation potentially influences EGLN and HIF1A levels, impacting cellular responses to hypoxia. We examined 96 HNSCC patients and three cell lines, analyzing gene expression of EGLN1-3, HIF1A, CA9, VEGF, and GLUT1 at the mRNA level and EGLN1 protein levels. Methylation levels of EGLNs and HIF1A were assessed through high-resolution melting analysis. Bioinformatics tools were employed to characterize associations between EGLN1-3 and HIF1A expression and methylation. We found significantly higher mRNA levels of EGLN3, HIF1A, GLUT1, VEGF, and CA9 (p = 0.021; p < 0.0001; p < 0.0001; p = 0.004, and p < 0.0001, respectively) genes in tumor tissues compared to normal ones and downregulation of the EGLN1 mRNA level in tumor tissues (p = 0.0013). In HNSCC patients with hypermethylation of HIF1A in normal tissue, we noted a reduction in HIF1A mRNA levels compared to tumor tissue (p = 0.04). In conclusion, the differential expression of EGLN and HIF1A genes in HNSCC tumors compared to normal tissues influences patients' overall survival, highlighting their role in tumor development. Moreover, DNA methylation could be responsible for HIF1A suppression in the normal tissues of HNSCC patients.

Induction of Peroxiredoxin 1 by Hypoxia Promotes Cellular Autophagy and Cell Proliferation in Oral Leukoplakia via HIF-1α/BNIP3 Pathway

Hypoxia is a key trigger in the transformation of oral leukoplakia into oral cancer. However, it is still too early to determine the role of hypoxia in the development of oral leukoplakia. Prx1, an antioxidant protein, upregulated by hypoxia, regulates cellular autophagy in leukoplakia. This study aimed to understand the mechanisms by which hypoxia induces Prx1 expression during autophagy in oral leukoplakia. We used an experimental model of tongue epithelial hyperplasia induced by 4-nitroquinoline-1-oxide (4NQO) and dysplastic oral keratinocytes. Prx1 knockdown DOK cells, Leuk-1 cells and control cells were harvested, and cell proliferation was assayed using the Cell Counting Kit-8. Several hypoxia and autophagy-related proteins were examined using quantitative real-time polymerase chain reaction, immunohistochemistry, immunofluorescence, and western blotting in cells and mouse tongue tissues. In addition, the ultrastructure of the cells was observed by transmission electron microscopy. Hypoxia induces cell proliferation, autophagic vesicles and the expression of Prx1, BNIP3, LC3II/I and Beclin-1 in DOK and Leuk-1 cells. However, these effects were all attenuated by Prx1 knockdown. Histologically, 4NQO induced epithelial hyperplasia in the tongue mucosa. The expression of proliferation marker PCNA, autophagy-related proteins LC3B and Beclin-1, as well as HIF-1α/BNIP3 was significantly lower in the tongue tissues of Prx1flox/flox:Cre+ mice compared with Prx1flox/flox mice. In Prx1flox/flox:Cre+ mice, an increased expression of HIF-1α/BNIP3, LC3B and Beclin-1 was detected in epithelial hyperplasia tongue tissues compared to normal tissues. The current study suggests that Prx1 may promotes cell proliferation and autophagy in oral leukoplakia cells via the HIF-1α/BNIP3 pathway.

Anlotinib suppressed tumor cell proliferation and migration in hypopharyngeal carcinoma

OBJECTIVE

The purpose of this study is to study the in-vitro effects of multitarget inhibitor anlotinib on hypopharyngeal cancer cell proliferation and cell migration, and the underlying mechanism, which will provide new drug choices for hypopharyngeal cancer treatment.

METHODS

The Hypopharyngeal cancer Fadu cells were treated with anlotinib at a concentration of 0, 5, and 10 μmoL/L, respectively. Cell counting kit-8 and the colony-forming assay were used to detect the inhibition of cell proliferation. Wound-healing assay and transwell assay were used to detect the migration and invasion ability of cells. Flow cytometry was used to detect the effects of anlotinib on cell cycle and apoptosis. RT-qPCR and Western blot were used to measure gene expression levels.

RESULTS

CCK-8 and colony-forming assay showed that anlotinib could significantly inhibit cell proliferative activity. Wound-healing assay and transwell assay showed that anlotinib could inhibit cell migration and scratch. These results showed that anlotinib has obvious antitumor activity. Flow cell cycle experiment showed that anlotinib could promote Fadu cell apoptosis and block the G2/M phase for inhibiting cell proliferation. In addition, anlotinib decreased the expression of HIF-1α.

CONCLUSIONS

Anlotinib has an excellent suppressing effect on the proliferation, migration, and invasion of hypopharyngeal cancer Fadu cells in-vitro. Moreover, it can play an anti-tumor role through blocking cell cycle G2/M and promoting apoptosis, which may be related to the decrease of HIF-1a expression. Our study would provide a potential treatment method for patients with hypopharyngeal cancer.

LEVEL OF EVIDENCE

Level 3.

Diagnostic, Prognostic, and Therapeutic Role for Angiogenesis Markers in Head and Neck Squamous Cell Carcinoma: A Narrative Review

Despite refinements to diagnostic and therapeutic approaches over the last two decades, the outcome of patients with head and neck squamous cell carcinoma (HNSCC) has not shown substantial improvements, especially regarding those with advanced-stage disease. Angiogenesis is believed to be a turning point in the development of solid tumors, being a premise for mass growth and potential distant dissemination. Cancer-induced angiogenesis is a result of increased expression of angiogenic factors, decreased expression of anti-angiogenic factors, or a combination of both. The assessment of angiogenesis has also emerged as a potentially useful biological prognostic and predictive factor in HNSCC. The aim of this review is to assess the level of current knowledge on the neo-angiogenesis markers involved in the biology, behavior, and prognosis of HNSCC. A search (between 1 January 2012 and 10 October 2022) was run in PubMed, Scopus, and Web of Science electronic databases. After full-text screening and application of inclusion/exclusion criteria, 84 articles are included. The current knowledge and debate on angiogenesis in HNSCC presented in the eligible articles are stratified as follows: (i) diagnostic markers; (ii) prognostic markers; (iii) predictive markers; and (iv) markers with a potential therapeutic role. Angiogenesis is a biological and pathological indicator of malignancies progression and has negative implications in prognosis of some solid tumors; several signals capable of tripping the "angiogenic switch" have also been identified in HNSCC. Although several studies suggested that antiangiogenic agents might be a valuable adjunct to conventional chemo-radiation of HNSCC, their long-term therapeutic value remains uncertain. Further investigations are required on combinations of antiangiogenic agents with conventional chemotherapeutic ones, immunotherapeutic and molecularly targeted agents in HNSCC. Additional data are necessary to pinpoint which patients could benefit most from these treatments.

Hypoxia disrupt tight junctions and promote metastasis of oral squamous cell carcinoma via loss of par3

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a highly malignant tumor that is frequently associated with lymph node metastasis, resulting in poor prognosis and survival in patients. In the tumor microenvironment, hypoxia plays an important role in regulating cellular responses such as progressive and rapid growth and metastasis. In these processes, tumor cells autonomously undergo diverse transitions and acquire functions. However, hypoxia-induced transition of OSCC and the involvement of hypoxia in OSCC metastasis remain unclear. Therefore, in this study, we aimed to elucidate the mechanism of hypoxia-induced OSCC metastasis and particularly, its impact on tight junctions (TJs).

METHODS

The expression of hypoxia-inducible factor 1-alpha (HIF-1α) was detected in tumor tissues and adjacent normal tissues from 29 patients with OSCC using reverse transcription quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry (IHC). The migration and invasion abilities of OSCC cell lines treated with small interfering (si)RNA targeting HIF-1α or cultured in hypoxic conditions were analyzed using Transwell assays. The effect of HIF-1α expression on in vivo tumor metastasis of OSCC cells was evaluated using lung metastasis model.

RESULTS

HIF-1α was overexpressed in patients with OSCC. OSCC metastasis was correlated with HIF-1α expression in OSCC tissues. Hypoxia increased the migration and invasion abilities of OSCC cell lines by regulating the expression and localization of partitioning-defective protein 3 (Par3) and TJs. Furthermore, HIF-1α silencing effectively decreased the invasion and migration abilities of OSCC cell lines and restored TJ expression and localization via Par3. The expression of HIF-1α was positively regulated the OSCC metastasis in vivo.

CONCLUSIONS

Hypoxia promotes OSCC metastasis by regulating the expression and localization of Par3 and TJ proteins. HIF-1α positively correlates to OSCC metastasis. Lastly, HIF-1α expression could regulate the expression of Par3 and TJs in OSCC. This finding may aid in elucidating the molecular mechanisms of OSCC metastasis and progression and developing new diagnostic and therapeutic approaches for OSCC metastasis.

The role of VEGF in cancer-induced angiogenesis and research progress of drugs targeting VEGF

Angiogenesis is a double-edged sword; it is a mechanism that defines the boundary between health and disease. In spite of its central role in physiological homeostasis, it provides the oxygen and nutrition needed by tumor cells to proceed from dormancy if pro-angiogenic factors tip the balance in favor of tumor angiogenesis. Among pro-angiogenic factors, vascular endothelial growth factor (VEGF) is a prominent target in therapeutic methods due to its strategic involvement in the formation of anomalous tumor vasculature. In addition, VEGF exhibits immune-regulatory properties which suppress immune cell antitumor activity. VEGF signaling through its receptors is an integral part of tumoral angiogenic approaches. A wide variety of medicines have been designed to target the ligands and receptors of this pro-angiogenic superfamily. Herein, we summarize the direct and indirect molecular mechanisms of VEGF to demonstrate its versatile role in the context of cancer angiogenesis and current transformative VEGF-targeted strategies interfering with tumor growth.

Overcoming the Impact of Hypoxia in Driving Radiotherapy Resistance in Head and Neck Squamous Cell Carcinoma

Hypoxia is very common in most solid tumours and is a driving force for malignant progression as well as radiotherapy and chemotherapy resistance. Incidences of head and neck squamous cell carcinoma (HNSCC) have increased in the last decade and radiotherapy is a major therapeutic technique utilised in the treatment of the tumours. However, effectiveness of radiotherapy is hindered by resistance mechanisms and most notably by hypoxia, leading to poor patient prognosis of HNSCC patients. The phenomenon of hypoxia-induced radioresistance was identified nearly half a century ago, yet despite this, little progress has been made in overcoming the physical lack of oxygen. Therefore, a more detailed understanding of the molecular mechanisms of hypoxia and the underpinning radiobiological response of tumours to this phenotype is much needed. In this review, we will provide an up-to-date overview of how hypoxia alters molecular and cellular processes contributing to radioresistance, particularly in the context of HNSCC, and what strategies have and could be explored to overcome hypoxia-induced radioresistance.

Radiotherapy resistance: identifying universal biomarkers for various human cancers

Radiotherapy (RT) is considered as a standard in the treatment of most solid cancers, including glioblastoma, lung, breast, rectal, prostate, colorectal, cervical, esophageal, and head and neck cancers. The main challenge in RT is tumor cell radioresistance associated with a high risk of locoregional relapse and distant metastasis. Despite significant progress in understanding mechanisms of radioresistance, its prediction and overcoming remain unresolved. This review presents the state-of-the-art for the potential universal biomarkers correlated to the radioresistance and poor outcome in different cancers. We describe radioresistance biomarkers functionally attributed to DNA repair, signal transduction, hypoxia, and angiogenesis. We also focus on high throughput genetic and proteomic studies, which revealed a set of molecular biomarkers related to radioresistance. In conclusion, we discuss biomarkers which are overlapped in most several cancers.

Intrabody Targeting HIF-1α Mediates Transcriptional Downregulation of Target Genes Related to Solid Tumors

Uncontrolled growth of solid tumors will result in a hallmark hypoxic condition, whereby the key transcriptional regulator of hypoxia inducible factor-1α (HIF-1α) will be stabilized to activate the transcription of target genes that are responsible for the metabolism, proliferation, and metastasis of tumor cells. Targeting and inhibiting the transcriptional activity of HIF-1 may provide an interesting strategy for cancer therapy. In the present study, an immune library and a synthetic library were constructed for the phage display selection of Nbs against recombinant PAS B domain protein (rPasB) of HIF-1α. After panning and screening, seven different nanobodies (Nbs) were selected, of which five were confirmed via immunoprecipitation to target the native HIF-1α subunit. The inhibitory effect of the selected Nbs on HIF-1 induced activation of target genes has been evaluated after intracellular expression of these Nbs in HeLa cells. The dramatic inhibition of both intrabody formats on the expression of HIF-1-related target genes has been confirmed, which indicated the inhibitory efficacy of selected Nbs on the transcriptional activity of HIF-1.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

The regulation of immune checkpoints by the hypoxic tumor microenvironment

The tumor microenvironment (TME) influences the occurrence and progression of tumors, and hypoxia is an important characteristic of the TME. The expression of programmed death 1 (PD1)/programmed death-ligand 1 (PDL1), cytotoxic T-lymphocyte-associated antigen 4 (CTLA4), and other immune checkpoints in hypoxic malignant tumors is often significantly increased, and is associated with poor prognosis. The application of immune checkpoint inhibitors (ICIs) for treating lung cancer, urothelial carcinoma, and gynecological tumors has achieved encouraging efficacy; however, the rate of efficacy of ICI single-drug treatment is only about 20%. In the present review, we discuss the possible mechanisms by which the hypoxic TME regulates immune checkpoints. By activating hypoxia-inducible factor-1α (HIF-1α), regulating the adenosine (Ado)-A2aR pathway, regulating the glycolytic pathway, and driving epithelial-mesenchymal transition (EMT) and other biological pathways, hypoxia regulates the expression levels of CTLA4, PD1, PDL1, CD47, lymphocyte activation gene 3 (LAG3), T-cell immunoglobulin and mucin domain 3 (TIM3), and other immune checkpoints, which interfere with the immune effector cell anti-tumor response and provide convenient conditions for tumors to escape immune surveillance. The combination of HIF-1α inhibitors, Ado-inhibiting tumor immune microenvironment regulatory drugs, and other drugs with ICIs has good efficacy in both preclinical studies and phase I-II clinical studies. Exploring the effects of TME hypoxia on the expression of immune checkpoints and the function of infiltrating immune cells has greatly clarified the relationship between the hypoxic TME and immune escape, which is of great significance for the development of new drugs and the search for predictive markers of the efficacy of immunotherapy for treating malignant tumors. In the future, combination therapy with hypoxia pathway inhibitors and ICIs may be an effective anti-tumor treatment strategy.