Risk factors and clinical impact of seroma formation following laparoscopic inguinal hernia repair: a retrospective study.

BACKGROUND: Although laparoscopic inguinal hernia repair (LIHR) has advantages over open surgery, postoperative seroma formation remains an issue. This study aimed to investigate the risk factors and clinical outcomes of seroma formation in patients undergoing LIHR. METHODS: From January 2016 to March 2023, clinical data of patients who underwent LIHR were retrospectively analyzed. Patients who developed seroma and those who did not were classified into the seroma and non-seroma groups, respectively. The demographic and clinical characteristics were compared between the two groups. Univariate and multivariate logistic regression analyses were performed for variables of interest. The receiver operating characteristic curve was used to evaluate the risk factors of the binary logistic model, and the cutoff value for each risk factor was obtained. RESULTS: Data of 128 patients were evaluated. Compared with patients in the non-seroma group, those in the seroma group had a higher body mass index (BMI) (P < 0.001), more direct hernias (P < 0.001), larger hernial orifice size (P < 0.001), more laparoscopic total extraperitoneal hernioplasty (TEP) (P < 0.001), more frequent reduction of hernial sac (P = 0.011), and lower preoperative serum albumin level (PSAL) (P < 0.001). Multivariate logistic regression analyses performed on these variables showed that high BMI (P = 0.005), large hernial orifice (P = 0.001), TEP (P = 0.033), and low PSAL (P = 0.009) were risk factors for seroma formation. Compared with the non-seroma group, the seroma group exhibited a higher numerical rating scale score for postoperative pain (P < 0.001), and longer hospital stays (P = 0.032). CONCLUSIONS: BMI (> 24.5 kg/m2), hernial orifice size (> 2.5 cm), TEP, and PSAL (< 32.5 g/L) were independent risk factors of postoperative seroma formation in patients who underwent LIHR. Although most seromas resolve spontaneously without surgical intervention, seroma formation results in increased patient pain and prolonged hospital stay.

THAP3 recruits SMYD3 to OXPHOS genes and epigenetically promotes mitochondrial respiration in hepatocellular carcinoma.

Mitochondria harbor the oxidative phosphorylation (OXPHOS) system to sustain cellular respiration. However, the transcriptional regulation of OXPHOS remains largely unexplored. Through the cancer genome atlas (TCGA) transcriptome analysis, transcription factor THAP domain-containing 3 (THAP3) was found to be strongly associated with OXPHOS gene expression. Mechanistically, THAP3 recruited the histone methyltransferase SET and MYND domain-containing protein 3 (SMYD3) to upregulate H3K4me3 and promote OXPHOS gene expression. The levels of THAP3 and SMYD3 were altered by metabolic cues. They collaboratively supported liver cancer cell proliferation and colony formation. In clinical human liver cancer, both of them were overexpressed. THAP3 positively correlated with OXPHOS gene expression. Together, THAP3 cooperates with SMYD3 to epigenetically upregulate cellular respiration and liver cancer cell proliferation.

SUCLG1 restricts POLRMT succinylation to enhance mitochondrial biogenesis and leukemia progression.

Mitochondria are cellular powerhouses that generate energy through the electron transport chain (ETC). The mitochondrial genome (mtDNA) encodes essential ETC proteins in a compartmentalized manner, however, the mechanism underlying metabolic regulation of mtDNA function remains unknown. Here, we report that expression of tricarboxylic acid cycle enzyme succinate-CoA ligase SUCLG1 strongly correlates with ETC genes across various TCGA cancer transcriptomes. Mechanistically, SUCLG1 restricts succinyl-CoA levels to suppress the succinylation of mitochondrial RNA polymerase (POLRMT). Lysine 622 succinylation disrupts the interaction of POLRMT with mtDNA and mitochondrial transcription factors. SUCLG1-mediated POLRMT hyposuccinylation maintains mtDNA transcription, mitochondrial biogenesis, and leukemia cell proliferation. Specifically, leukemia-promoting FMS-like tyrosine kinase 3 (FLT3) mutations modulate nuclear transcription and upregulate SUCLG1 expression to reduce succinyl-CoA and POLRMT succinylation, resulting in enhanced mitobiogenesis. In line, genetic depletion of POLRMT or SUCLG1 significantly delays disease progression in mouse and humanized leukemia models. Importantly, succinyl-CoA level and POLRMT succinylation are downregulated in FLT3-mutated clinical leukemia samples, linking enhanced mitobiogenesis to cancer progression. Together, SUCLG1 connects succinyl-CoA with POLRMT succinylation to modulate mitochondrial function and cancer development.

Organelle-dependent polyprotein designs enable stoichiometric expression of nitrogen fixation components targeted to mitochondria.

Introducing nitrogen fixation (nif  ) genes into eukaryotic genomes and targeting Nif components to mitochondria or chloroplasts is a promising strategy for engineering nitrogen-fixing plants. A prerequisite for achieving nitrogen fixation in crops is stable and stoichiometric expression of each component in organelles. Previously, we designed a polyprotein-based nitrogenase system depending on Tobacco Etch Virus protease (TEVp) to release functional Nif components from five polyproteins. Although this system satisfies the demand for specific expression ratios of Nif components in Escherichia coli, we encountered issues with TEVp cleavage of polyproteins targeted to yeast mitochondria. To overcome this obstacle, a version of the Nif polyprotein system was constructed by replacing TEVp cleavage sites with minimal peptide sequences, identified by knowledge-based engineering, that are susceptible to cleavage by the endogenous mitochondrial-processing peptidase. This replacement not only further reduces the number of genes required, but also prevents potential precleavage of polyproteins outside the target organelle. This version of the polyprotein-based nitrogenase system achieved levels of nitrogenase activity in E. coli, comparable to those observed with the TEVp-based polyprotein nitrogenase system. When applied to yeast mitochondria, stable and balanced expression of Nif components was realized. This strategy has potential advantages, not only for transferring nitrogen fixation to eukaryotic cells, but also for the engineering of other metabolic pathways that require mitochondrial compartmentalization.

Emerging therapies in cancer metabolism.

Metabolic reprogramming in cancer is not only a biological hallmark but also reveals treatment vulnerabilities. Numerous metabolic molecules have shown promise as treatment targets to impede tumor progression in preclinical studies, with some advancing to clinical trials. However, the intricacy and adaptability of metabolic networks hinder the effectiveness of metabolic therapies. This review summarizes the metabolic targets for cancer treatment and provides an overview of the current status of clinical trials targeting cancer metabolism. Additionally, we decipher crucial factors that limit the efficacy of metabolism-based therapies and propose future directions. With advances in integrating multi-omics, single-cell, and spatial technologies, as well as the ability to track metabolic adaptation more precisely and dynamically, clinicians can personalize metabolic therapies for improved cancer treatment.

LncRNA-PEAK1 promotes neuronal apoptosis after intracerebral hemorrhage by miR-466i-5p/caspase 8 axis.

Background: At present, the treatment of intracerebral hemorrhage (ICH)-induced secondary brain injury (ISB) is limited, and the curative effect is not good. Long noncoding RNAs (lncRNAs) have been reported to play a role in ISB after ICH. We preliminarily monitored the induction effect of lncRNA-pseudopodium-enriched atypical kinase 1 (PEAK1) on neuronal cell apoptosis after ICH through our previous study and further experimental verification. However, the specific role and mechanism of lncRNA-PEAK1 in neuronal cell apoptosis after ICH have not been reported. Methods: ICH cell models were established with hemin. Pro-inflammatory cytokines, cell proliferation, and apoptosis were evaluated by enzyme-linked immunosorbent assay, Cell Counting Kit-8 assay, flow cytometry, and terminal deoxynucleotidyl transferase dUTP nick end labeling, respectively. Moreover, lncRNA expression associated with apoptosis was confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The biological functions of lncRNA-PEAK1, miR-466i-5p, and caspase8 were conducted in vitro. Further, we used bioinformatics, a dual-luciferase reporter assay, and rescue experiments to understand the mechanisms of competitive endogenous RNAs. Results: qRT-PCR revealed that lncRNA-PEAK1 was markedly upregulated in ICH cell models. LncRNA-PEAK1 knockdown decreased the interleukin-1ß and tumor necrosis factor-alpha levels, promoted cell proliferation, weakened cell apoptosis, and downregulated the key molecular protein levels involved in the cell apoptosis pathway. Bioinformatics analysis and dual-luciferase reporter assay revealed that lncRNA bound to miR-466i-5p, and caspase 8 was a target of miR-466i-5p. The mechanistic analysis demonstrated that lncRNA-PEAK1/miR-466i-5p promoted neuronal cell apoptosis by activating the apoptosis pathway through caspase8 after ICH. Conclusion: Collectively, our investigation identified that the lncRNA-PEAK1/miR-446i-5p/caspase8 axis is closely related to neuronal cell apoptosis after ICH. Additionally, lncRNA-PEAK1 may be a potential target for ICH intervention.

The functional change of the P2X7R containing the Ala348 to Thr polymorphism is associated with the pathogenesis of gout.

Our previous study has shown that ATP action on P2X7R could be the second signal to induce the onset of gouty arthritis. However, the functional changes of P2X7R single nucleotide polymorphisms (SNPs) on the effects of ATP-P2X7R-IL-1ß signaling pathway and uric acid remained unknown. We aimed to investigate the association between the functional change of P2X7R containing the Ala348 to Thr polymorphisms (rs1718119) and the pathogenesis of gout. First, 270 gout patients and 70 hyperuricemic patients (without gout attack history in recent 5 years) were recruited for genotyping. In addition, the changes of ATP-induced pore formation were assessed in HEK-293T cells overexpressing different mutants in P2RX7, and the effects on P2X7R-NLRP3-IL-1ß pathway activation were explored in P2RX7 overexpression THP-1 cells. The risk allele for gout was A at rs1718119, and the AA and AG genotypes exhibited a higher risk of gout. Furthermore, Ala348 to Thr mutants increased P2X7-dependent ethidium+ bromide uptake, upregulated IL-1ß and NLRP3 levels as compared to the wild-type. We suggest that genetic polymorphisms of P2X7R containing the Ala348 to Thr are associated with the increased risk of gout, showing an enhanced gain-of-function effect on the development of this disease.

Factors affecting the accuracy of anti-BRAF V600E immunohistochemistry results in ameloblastomas.

BACKGROUND: There are still some controversies about the results of anti-BRAF V600E-specific antibody immunohistochemistry in ameloblastomas. This study aimed to examine the accuracy of V600E-specific antibody immunohistochemistry in detection of BRAF V600E mutation in ameloblastoma tissue sections of different ages. METHODS: The BRAF V600E status of 64 ameloblastoma specimens was assessed using both Sanger sequencing and V600E-specific antibody immunohistochemistry, and the sensitivity, specificity, positive predictive value, and negative predictive value were calculated. The difference in V600E-specific antibody immunohistochemistry staining intensity among the three groups of ameloblastoma tissue blocks of different ages was evaluated by chi-square test. The consistency between V600E-specific antibody immunohistochemistry and DNA sequencing results and the V600E-specific antibody immunohistochemistry staining intensity of 15 paired newly-cut and 3-month storage sections of the same 15 ameloblastomas were also compared. RESULTS: For detection of BRAF V600E mutation, the V600E-specific antibody immunohistochemistry had high sensitivity (98.21% 55/56), specificity (87.5% 7/8), positive predictive value (98.21% 55/56), and negative predictive value (87.5% 7/8). Heterogeneity of the staining intensity was observed in the same tissue section, but all or none expression pattern was noticed in the solid tumor nests. The storage time of paraffin tissue blocks ranging from 2 to 14 years did not affect the V600E-specific antibody-positive staining intensity. However, the three-month storage sections showed a significant diminishment of V600E-specific antibody-positive staining signals. CONCLUSIONS: The BRAF V600E-specific antibody immunohistochemistry is suitable for routine detection of BRAF V600E mutation in ameloblastomas. The all or none expression pattern suggests the BRAF V600E mutation may be an early event in the pathogenesis of ameloblastoma.

Ferroptosis heterogeneity in triple-negative breast cancer reveals an innovative immunotherapy combination strategy.

Treatment of triple-negative breast cancer (TNBC) remains challenging. Deciphering the orchestration of metabolic pathways in regulating ferroptosis will provide new insights into TNBC therapeutic strategies. Here, we integrated the multiomics data of our large TNBC cohort (n = 465) to develop the ferroptosis atlas. We discovered that TNBCs had heterogeneous phenotypes in ferroptosis-related metabolites and metabolic pathways. The luminal androgen receptor (LAR) subtype of TNBC was characterized by the upregulation of oxidized phosphatidylethanolamines and glutathione metabolism (especially GPX4), which allowed the utilization of GPX4 inhibitors to induce ferroptosis. Furthermore, we verified that GPX4 inhibition not only induced tumor ferroptosis but also enhanced antitumor immunity. The combination of GPX4 inhibitors and anti-PD1 possessed greater therapeutic efficacy than monotherapy. Clinically, higher GPX4 expression correlated with lower cytolytic scores and worse prognosis in immunotherapy cohorts. Collectively, this study demonstrated the ferroptosis landscape of TNBC and revealed an innovative immunotherapy combination strategy for refractory LAR tumors.

Ferroptosis and renal fibrosis: A new target for the future (Review).

Ferroptosis is a type of non-apoptotic controlled cell death triggered by oxidative stress and iron-dependent lipid peroxidation. Ferroptosis is regulated by signalling pathways that are associated with metabolism, including glutathione peroxidase 4 dysfunction, the cystine/glutamate antiporter system, lipid peroxidation and inadequate iron metabolism. Ferroptosis is associated with renal fibrosis; however, further research is required to understand the specific molecular mechanisms involved. The present review aimed to discuss the known molecular mechanisms of ferroptosis and outline the biological reactions that occur during renal fibrosis that may be associated with ferroptosis. Further investigation into the association between ferroptosis and renal fibrosis may lead to the development of novel treatment methods.

Metabolism in Hematopoiesis and Its Malignancy.

Hematopoietic stem cells (HSCs) are multipotent stem cells that can self-renew and generate all blood cells of different lineages. The system is under tight control in order to maintain a precise equilibrium of the HSC pool and the effective production of mature blood cells to support various biological activities. Cell metabolism can regulate different molecular activities, such as epigenetic modification and cell cycle regulation, and subsequently affects the function and maintenance of HSC. Upon malignant transformation, oncogenic drivers in malignant hematopoietic cells can remodel the metabolic pathways for supporting the oncogenic growth. The dysregulation of metabolism results in oncogene addiction, implying the development of malignancy-specific metabolism-targeted therapy. In this chapter, we will discuss the significance of different metabolic pathways in hematopoiesis, specifically, the distinctive metabolic dependency in hematopoietic malignancies and potential metabolic therapy.

Combined evaluation of both WEE1 and phosphorylated cyclin dependent kinase 1 expressions in oral squamous cell carcinomas predicts cancer recurrence and progression.

Background/purpose: WEE1 is a mitotic inhibitor at G2 checkpoint of the cell cycle that negatively regulates cyclin-dependent kinase 1 (CDK1) through inhibitory phosphorylation. This study assessed whether the expressions of both WEE1 and phosphorylated CDK1 in specimens of oral squamous cell carcinoma (OSCC) might predict the OSCC recurrence and progression. Materials and methods: This study used immunohistochemistry to examine the expressions of WEE1 and phosphorylated CDK1 proteins in 75 specimens of OSCC and 30 specimens of normal oral mucosa (NOM). Results: The mean WEE1 labeling index (LI) was significantly lower in 75 OSCC samples than in 30 NOM samples (P < 0.001), whereas the mean phosphorylated CDK1 LI was significantly higher in 75 OSCC samples than in 30 NOM samples (P < 0.001). We found a significant association of low WEE1 LI (<21%) with OSCC recurrence (P = 0.047) and a significant association of low phosphorylated CDK1 LI (<10%) with larger tumor size (P = 0.011) and more advanced clinical stages (P = 0.021) of OSCC. Conclusion: Combined evaluation of WEE1 and phosphorylated CDK1 LI in specimens of OSCC may predict the OSCC recurrence and progression.

Mitochondria transfer and transplantation in human health and diseases.

Mitochondria are dynamic organelles responsible for energy production and cell metabolism. Disorders in mitochondrial function impair tissue integrity and have been implicated in multiple human diseases. Rather than constrained in host cells, mitochondria were recently found to actively travel between cells through nanotubes or extracellular vesicles. Mitochondria transportation represents a key mechanism of intercellular communication implicated in metabolic homeostasis, immune response, and stress signaling. Here we reviewed recent progress in mitochondria transfer under physiological and pathological conditions. Specifically, tumor cells imported mitochondria from adjacent cells in the microenvironment which potentially modulated cancer progression. Intercellular mitochondria trafficking also inspired therapeutic intervention of human diseases with mitochondria transplantation. Artificial mitochondria, generated through mitochondria genome engineering or mitochondria-nucleus hybridization, further advanced our understanding of mitochondrial biology and its therapeutic potential. Innovative tools and animal models of mitochondria transplantation will assist the development of new therapies for mitochondrial dysfunction-related diseases.

Optimization of Early Antimicrobial Strategies for Lung Transplant Recipients Based on Metagenomic Next-Generation Sequencing.

The management of perioperative antibiotic options after lung transplantation varies widely around the world, but there is a common trend to limit antibiotic use duration. Metagenomic next-generation sequencing (mNGS) has become a hot spot in clinical pathogen detection due to its precise, rapid, and wide detection spectrum of pathogens. Thus, we defined a new antibiotic regimen adjustment strategy in the very early stage (within 7 days) after lung transplantation mainly depending on mNGS reports combined with clinical conditions to reduce the use of antibiotics. To verify the clinical effect of the strategy, we carried out this research. Thirty patients who underwent lung transplantation were finally included, whose information including etiology, antibiotic adjustment, and the effect of our strategy was recorded. Lung transplant recipients in this study were prescribed with initial antibiotic regimen immediately after surgery; their antibiotic regimens were adjusted according to the strategy. According to our study, the entire effectiveness of the strategy was 90.0% (27/30). Besides, a total of 86 samples containing donor lung tissue, recipient lung tissue, and bronchoalveolar lavage fluid (BALF) were obtained in this study; they were all sent to mNGS test, while BALF was also sent to pathogen culture. Their results showed that the positive rate of BALF samples was higher (86.67%) than that of donor's lung tissue (20.0%) or recipient's lung tissue (13.33%) by mNGS test, indicating BALF samples are more valuable than other clinical samples from early postoperative period to guide the early adjustment of antibiotics after lung transplantation. It is effective for mNGS combined with traditional methods and clinical situations to optimize antibiotic regimens in lung transplantation recipients within 7 days after surgery.

Comparisons of histological features among primary oral squamous cell carcinomas before and after adjuvant chemotherapy and their lymph node metastatic cancer lesions after adjuvant chemotherapy.

BACKGROUND/PURPOSE: Adjuvant chemotherapy has been used to control the primary oral squamous cell carcinoma (OSCC) size prior to surgical excision of the cancer. This study aimed to explore the histological changes of primary OSCCs and their cervical lymph node metastatic cancer lesions after chemotherapy. MATERIALS AND METHODS: Thirty-three OSCC patients with eleven having cervical lymph node metastases received adjuvant chemotherapy before surgical excision of their cancer lesions. Hematoxylin and eosin-stained tissue sections of incisional biopsy, surgical excision, and cervical lymph node metastatic cancer lesion specimens were compared microscopically to observe the histological changes in the cancer tissues after chemotherapy. RESULTS: Common histological features could be found in the primary OSCCs and their cervical lymph node metastatic cancer lesions after chemotherapy. These included direct killing of cancer cells by chemotherapeutic agents, resulting in cancer cell necrosis and degeneration in the early phase, and squamous and keratinizing metaplasia of drug-induced cancer cells, leading to individual cell keratinization and keratin pearl formation in the later phase. There were also small nests of drug-resistant proliferating cancer cells in the inflamed fibrous connective tissue stroma. The most characteristic histological feature in the metastatic lymph nodes after chemotherapy was the keratinizing metaplasia of the metastatic cancer cells, resulting in the formation of epidermoid cyst-like lesions. CONCLUSION: Although the cancer reduces its size after chemotherapy, residual cancer cells are consistently present in the primary OSCC lesions after chemotherapy. Therefore, wide surgical resection of the cancer is still needed to ensure the complete removal of all cancer tissues.

Enrichment of SOX2-Positive Cells in BRAF V600E Mutated and Recurrent Ameloblastoma.

Ameloblastoma is the most common benign odontogenic neoplasm, but with an aggressive behavior and a high recurrence rate. Nowadays wide surgical resection is the current recommended treatment, which can cause further loss of function and esthetics. Recent studies point to the stem/progenitor cells as both initiators and propagators of the tumors. Elucidation of the cellular and molecular mechanisms underlying the tumor stem cells is of broad interest for understanding tumorigenesis and for developing effective targeted therapies. SRY related HMG box gene 2 (SOX2) is a transcription factor that plays important roles in development, stem cell renewal, and cancer formation. Few studies have revealed increased SOX2 expression in atypical ameloblastoma and ameloblastic carcinoma. For the development of personalized medicine for ameloblastoma, biomarkers that provide prognostic or predictive information regarding a tumor's nature or its response to treatment are essential. Thus, in this study, we aimed to study if SOX2-positive cells exist in ameloblastomas and their correlation with the clinicopathologic parameters. Our data suggested BRAF(V600E) mutation might contribute to the expansion of SOX2-positive cells. The identification of BRAF(V600E) mutation and the amplification of SOX2-positive cells in ameloblastomas imply the possible benefit of applying BRAF and SOX2 inhibitors in recurrent and un-resectable ameloblastomas.

The neutrophil elastase-upregulated placenta growth factor promotes the pathogenesis and progression of periodontal disease.

BACKGROUND: Periodontal disease is a chronic inflammatory disease. Given its high prevalence, especially in aging population, the detailed mechanisms about pathogenesis of periodontal disease are important issues for study. Neutrophil firstly infiltrates to periodontal disease-associated pathogen loci and amplifies the inflammatory response for host defense. However, excessive neutrophil-secreted neutrophil elastase (NE) damages the affected gingival. In lung and esophageal epithelium, NE had been proved to upregulate several growth factors including placenta growth factor (PGF). PGF is an angiogenic factor with proinflammatory properties, which mediates the progression of inflammatory disease. Therefore, we hypothesize excessive NE upregulates PGF and participates in the pathogenesis and progression of periodontal disease. METHODS: In gingival epithelial cells (GEC), growth factors array demonstrated NE-increased growth factors and further be corroborated by Western blot assay and ELISA. The GEC inflammation was evaluated by ELISA. In mice, the immunohistochemistry results demonstrated ligature implantation-induced neutrophil infiltration and growth factor upregulation. By multiplex assay, the ligature-induced proinflammatory cytokines level in gingival crevicular fluid (GCF) were evaluated. Finally, alveolar bone absorption was analyzed by micro-CT images and H & E staining. RESULTS: NE upregulated PGF expression and secretion in GEC. PGF promoted GEC to secret IL-1ß, IL-6, and TNF-α in GCF In periodontal disease animal model, ligature implantation triggered NE infiltration and PGF expression. Blockade of PGF attenuated the ligature implantation-induced IL-1ß, IL-6, TNF-α and MIP-2 secretion and ameliorated the alveolar bone loss in mice. CONCLUSION: In conclusion, the NE-induced PGF triggers gingival epithelium inflammation and promotes the pathogenesis and progression of periodontal disease.

Clinical and histopathologic characteristics of submandibular gland in Stevens-Johnson syndrome: A comparative study.

OBJECTIVE: The objective of this study was to investigate the clinical manifestations and pathologic appearances of the submandibular gland (SMG) in Stevens-Johnson syndrome (SJS). STUDY DESIGN: Patients with autologous transplantation of SMG for treatment of severe dry eye between March 1998 and May 2018 were divided into the SJS group (70 cases) and non-SJS group (50 cases) according to the history of SJS. The SMG weight and computed tomography volume and salivary flow rate were measured. The concentration index and secretion index were estimated using scintigraphy with technetium-99m-pertechnetate. Histopathology studies of SMG tissues were conducted, and the acini parameters were measured using a digital image analyzer. RESULTS: A decreased computed tomography volume and weight was observed in 48.57% the SJS group and 2% in the non-SJS group (P < .01). The rest whole, acid-stimulated whole, and SMG rest salivary flow rates decreased in the SJS group (P < .05). The normal SMG concentration index (37.5% vs 96.67%, P < .001) and secretion index (35% vs 96.67%, P < .001) rates were lower in the SJS group than in the non-SJS group. The glandular parenchyma was reduced, the acinar space was widened, and the fat content was increased in the SJS group. CONCLUSION: SMG atrophic and degenerative changes occurred in the SJS group, with a decrease in salivary secretion function in more than half of the patients.

NOTCH1 signaling promotes protein stability of HER3 through the AKT pathway in squamous cell carcinoma of head and neck.

Epidermal growth factor receptor (EGFR) remains the sole druggable molecular target other than the PD1/PD-L1 pathway with meaningful clinical benefit in squamous cell carcinoma of head and neck (SCCHN). Human epidermal growth factor receptor 3 (HER3) confers the resistance to EGFR-targeted treatment in SCCHN. Thus, it is essential to determine the distribution and regulatory mechanisms of HER3 in SCCHN. We explored the prevalence of HER3 expression and its distribution within SCCHN by immunohistochemical staining and clinicopathological correlations were analyzed. The regulatory mechanism of HER3 expression was then dissected in vitro, using RT-PCR, Western blotting, and immunoprecipitation in a set of SCCHN cell lines. Subsequent in vivo validation in the murine model was also performed. We found that concomitant high expression of HER3 and its ligand NRG1 in SCCHN is associated with the increased presence of regional lymphatic metastasis and the majority of HER3 is located on the differentiated tumor cells. Further investigation revealed that HER3 is under positive control of NOTCH1 through transcriptional activation and inhibition of protein degradation through the polyubiquitination machinery via AKT pathway and USP8 deubiquitinating enzyme. In addition, loss of function of NOTCH1 suppresses HER3 expression through increased phosphorylation of serine 473 of AKT in SCCHN cells, and promotes the aggressiveness of the tumor cells. These data indicated that the level of HER3 is regulated by NOTCH1 in SCCHN both transcriptionally and post-translationally, and NOTCH1 is in a higher hierarchy in the regulatory system of the AKT pathway. Since NOTCH1 is inactivated in approximately 10% of SCCHN cases and this aberration strongly impacts the AKT pathway and diminishes HER3, exclusion of patients with NOTCH1-inactivated SCCHN may be beneficial for future clinical trials of HER3-targeting antibodies.