Inhibiting WEE1 and IKK-RELA Crosstalk Overcomes TNFα Resistance in Head and Neck Cancers

mSphere of Influence: Retreading old ground-the beauty in multi-omic data sets

Ethan L. Morgan works on human papillomaviruses (HPVs), with a specific interest in identifying how HPV induces tumor formation. In this mSphere of Influence article, he reflects on how three papers influenced him. "Comprehensive genomic characterization of head and neck squamous cell carcinomas" (The Cancer Genome Atlas Network, Nature 517:576-582, 2015, https://doi.org/10.1038/nature14129) and "Integrated genomic and molecular characterization of cervical cancer" (The Cancer Genome Atlas Network, Nature 543: 378-384, 2017, https://doi.org/10.1038/nature21386) showed him the power behind comprehensive multi-omic analyses to understand disease biology, while "Human papillomavirus E7 oncoprotein targets RNF168 to hijack the host DNA damage response" (J. Sitz et al., Proc Natl Acad Sci U S A 116:19552-19562, 2019, https://doi.org/10.1073/pnas.1906102116) reinforced how this can be used to undercover potential new drug targets in HPV-associated disease.

Double-strand DNA break repair: molecular mechanisms and therapeutic targets

Double-strand break (DSB), a significant DNA damage brought on by ionizing radiation, acts as an initiating signal in tumor radiotherapy, causing cancer cells death. The two primary pathways for DNA DSB repair in mammalian cells are nonhomologous end joining (NHEJ) and homologous recombination (HR), which cooperate and compete with one another to achieve effective repair. The DSB repair mechanism depends on numerous regulatory variables. DSB recognition and the recruitment of DNA repair components, for instance, depend on the MRE11-RAD50-NBS1 (MRN) complex and the Ku70/80 heterodimer/DNA-PKcs (DNA-PK) complex, whose control is crucial in determining the DSB repair pathway choice and efficiency of HR and NHEJ. In-depth elucidation on the DSB repair pathway's molecular mechanisms has greatly facilitated for creation of repair proteins or pathways-specific inhibitors to advance precise cancer therapy and boost the effectiveness of cancer radiotherapy. The architectures, roles, molecular processes, and inhibitors of significant target proteins in the DSB repair pathways are reviewed in this article. The strategy and application in cancer therapy are also discussed based on the advancement of inhibitors targeted DSB damage response and repair proteins.

Inhibition of USP14 promotes TNFα-induced cell death in head and neck squamous cell carcinoma (HNSCC)

TNFα is a key mediator of immune, chemotherapy and radiotherapy-induced cytotoxicity, but several cancers, including head and neck squamous cell carcinomas (HNSCC), display resistance to TNFα due to activation of the canonical NFκB pro-survival pathway. However, direct targeting of this pathway is associated with significant toxicity; thus, it is vital to identify novel mechanism(s) contributing to NFκB activation and TNFα resistance in cancer cells. Here, we demonstrate that the expression of proteasome-associated deubiquitinase USP14 is significantly increased in HNSCC and correlates with worse progression free survival in Human Papillomavirus (HPV)- HNSCC. Inhibition or depletion of USP14 inhibited the proliferation and survival of HNSCC cells. Further, USP14 inhibition reduced both basal and TNFα-inducible NFκB activity, NFκB-dependent gene expression and the nuclear translocation of the NFκB subunit RELA. Mechanistically, USP14 bound to both RELA and IκBα and reduced IκBα K48-ubiquitination leading to the degradation of IκBα, a critical inhibitor of the canonical NFκB pathway. Furthermore, we demonstrated that b-AP15, an inhibitor of USP14 and UCHL5, sensitized HNSCC cells to TNFα-mediated cell death, as well as radiation-induced cell death in vitro. Finally, b-AP15 delayed tumor growth and enhanced survival, both as a monotherapy and in combination with radiation, in HNSCC tumor xenograft models in vivo, which could be significantly attenuated by TNFα depletion. These data offer new insights into the activation of NFκB signaling in HNSCC and demonstrate that small molecule inhibitors targeting the ubiquitin pathway warrant further investigation as a novel therapeutic avenue to sensitize these cancers to TNFα- and radiation-induced cytotoxicity.

Combined Inhibition of IAPs and WEE1 Enhances TNFα- and Radiation-Induced Cell Death in Head and Neck Squamous Carcinoma

Head and neck squamous cell carcinoma (HNSCC) remains a prevalent diagnosis with current treatment options that include radiotherapy and immune-mediated therapies, in which tumor necrosis factor-α (TNFα) is a key mediator of cytotoxicity. However, HNSCC and other cancers often display TNFα resistance due to activation of the canonical IKK-NFκB/RELA pathway, which is activated by, and induces expression of, cellular inhibitors of apoptosis proteins (cIAPs). Our previous studies have demonstrated that the IAP inhibitor birinapant sensitized HNSCC to TNFα-dependent cell death in vitro and radiotherapy in vivo. Furthermore, we recently demonstrated that the inhibition of the G2/M checkpoint kinase WEE1 also sensitized HNSCC cells to TNFα-dependent cell death, due to the inhibition of the pro-survival IKK-NFκB/RELA complex. Given these observations, we hypothesized that dual-antagonist therapy targeting both IAP and WEE1 proteins may have the potential to synergistically sensitize HNSCC to TNFα-dependent cell death. Using the IAP inhibitor birinapant and the WEE1 inhibitor AZD1775, we show that combination treatment reduced cell viability, proliferation and survival when compared with individual treatment. Furthermore, combination treatment enhanced the sensitivity of HNSCC cells to TNFα-induced cytotoxicity via the induction of apoptosis and DNA damage. Additionally, birinapant and AZD1775 combination treatment decreased cell proliferation and survival in combination with radiotherapy, a critical source of TNFα. These results support further investigation of IAP and WEE1 inhibitor combinations in preclinical and clinical studies in HNSCC.

Upregulated miR-322-5p regulates cell cycle and promotes cell proliferation and apoptosis by directly targeting Wee1 in mice liver injury

Liver injury from any number of causes (e.g. chemical material, drugs and diet, viral infection) is a global health problem, and its mechanism is not clearly understood. MicroRNAs (miRNAs) expression profiling is gaining popularity because miRNAs, as key regulators in gene expression networks, can influence many biological processes and have also shown promise as biomarkers for disease. Previous studies reported the regulation effects of miRNAs in liver injury, whereas function and molecular mechanisms of miR-322-5p were still unclear. Therefore, our study focused on the biological role of miR-322-5p in carbon tetrachloride (CCl4)-induced liver injury proliferation, apoptosis, and cell cycle. A mouse model of CCl4-induced liver injury was established, and the transcriptomes and miRNAs transcriptomes of 2d and 5d liver tissues after injury were sequenced. The expression of miR-322-5p and the cell cycle genes were detected in liver tissues and Hepa1-6 cell line by miRNA RT-PCR, qRT-PCR. The effects of miR-322-5p on liver cell proliferation, cell cycle and apoptosis were evaluated using MTS assays and flow cytometry analysis. The relationship between miR-322-5p and Wee1 was predicted and confirmed by bioinformatics analysis and a dual luciferase reporter assay. Functional experiments, including an MTS assay and flow cytometric analysis, were performed to study the effects of Wee1. MiR-322-5p was upregulated in injury liver tissues, and downregulated miR-322-5p was proved to inhibit proliferation, apoptosis and arrest cell cycle at G2/M in vitro. The dual-luciferase reporter assay results indicated that miR-322-5p has a binding site at position 285 in the Wee1 3´UTR. The effects of miR-322-5p in proliferation and cell cycle regulation can be abolished by Wee1 through rescue experiments. By directly targeting Wee1 influenced the expression of several cell cycle factors, including Cyclin dependent kinase 1 (Cdk1), cyclin B1 (Ccnb1) and Cell division cyclin 25C (Cdc25C). MiR-322-5p may function as a suppressive factor by negatively controlling Wee1, thus, highlighting the potential role of miR-322-5p as a therapeutic target for liver injury.Abbreviations: ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; GSH: Glutathione, γ-glutamyl cysteinel + glycine; CCl4: Carbon tetrachloride; HE: Haematoxylin and eosin; KEGG: Kyoto Encyclopedia of Genes and Genomes.

Targeting DNA damage response as a potential therapeutic strategy for head and neck squamous cell carcinoma

Cells experience both endogenous and exogenous DNA damage daily. To maintain genome integrity and suppress tumorigenesis, individuals have evolutionarily acquired a series of repair functions, termed DNA damage response (DDR), to repair DNA damage and ensure the accurate transmission of genetic information. Defects in DNA damage repair pathways may lead to various diseases, including tumors. Accumulating evidence suggests that alterations in DDR-related genes, such as somatic or germline mutations, single nucleotide polymorphisms (SNPs), and promoter methylation, are closely related to the occurrence, development, and treatment of head and neck squamous cell carcinoma (HNSCC). Despite recent advances in surgery combined with radiotherapy, chemotherapy, or immunotherapy, there has been no substantial improvement in the survival rate of patients with HNSCC. Therefore, targeting DNA repair pathways may be a promising treatment for HNSCC. In this review, we summarized the sources of DNA damage and DNA damage repair pathways. Further, the role of DNA damage repair pathways in the development of HNSCC and the application of small molecule inhibitors targeting these pathways in the treatment of HNSCC were focused.