Background Glutamine is an abundant and versatile nutrient in cancer cells. Head and neck squamous cell carcinoma (HNSCC) was reported to be dependent on mainly glucose, not glutamine, for producing the energy required for survival and proliferation. Methods The roles of ASCT2 (SLC1A5) and associated glutamine metabolism were determined by the MTT, colony formation, glutamine uptake, intracellular glutathione, ROS detection, immunofluorescence, immunohistochemistry, and apoptosis enzyme-linked immunosorbent assays as well as animal studies. Results We found that glutamine is also critical for HNSCC. In this study, ASCT2, an amino acid transporter responsible for glutamine transport, in addition to LAT1 and GLS, is overexpressed in HNSCC and associated with poor survival. Using both in vivo and in vitro models, we found that knocking down ASCT2 by shRNAs or miR-137 or the combination of silencing ASCT2 and pharmacologically inhibiting SNAT2 via a small-molecule antagonist called V-9302 significantly suppressed intracellular glutamine levels and downstream glutamine metabolism, including glutathione production; these effects attenuated growth and proliferation, increased apoptosis and autophagy, and increased oxidative stress and mTORC1 pathway suppression in HNSCC. Additionally, silencing ASCT2 improved the response to cetuximab in HNSCC. Conclusions In summary, ASCT2-dependent glutamine uptake and subsequent glutamine metabolism are essential for HNSCC tumorigenesis, and the combination of glutamine uptake inhibitors and cetuximab presents a promising strategy for improving the outcomes of HNSCC patients.

Cetuximab inhibits HIF-1-regulated glycolysis in cancer cells, thereby reversing the Warburg effect and leading to inhibition of cancer cell metabolism. AMP-activated protein kinase (AMPK) is activated after cetuximab treatment, and a sustained AMPK activity is a mechanism contributing to cetuximab resistance. Here, we investigated how acetyl-CoA carboxylase (ACC), a downstream target of AMPK, rewires cancer metabolism in response to cetuximab treatment. We found that introduction of experimental ACC mutants lacking the AMPK phosphorylation sites (ACC1_S79A and ACC2_S212A) into head and neck squamous cell carcinoma (HNSCC) cells protected HNSCC cells from cetuximab-induced growth inhibition. HNSCC cells with acquired cetuximab resistance contained not only high levels of T172-phosphorylated AMPK and S79-phosphorylated ACC1 but also an increased level of total ACC. These findings were corroborated in tumor specimens of HNSCC patients treated with cetuximab. Cetuximab plus TOFA (an allosteric inhibitor of ACC) achieved remarkable growth inhibition of cetuximab-resistant HNSCC xenografts. Our data suggest a novel paradigm in which cetuximab-mediated activation of AMPK and subsequent phosphorylation and inhibition of ACC is followed by a compensatory increase in total ACC, which rewires cancer metabolism from glycolysis-dependent to lipogenesis-dependent.

Introduction: Perineural invasion (PNI), a key pathological feature of head and neck squamous cell carcinoma (HNSCC), predicts poor survival. However, the associated clinical characteristics remain uncertain, and the molecular mechanisms are largely unknown. Materials and methods: HNSCC gene expression and corresponding clinical data were downloaded from The Cancer Genome Atlas (TCGA). Prognostic subgroup analysis was performed, and potential PNI risk factors were assessed with logistic regression. PNI-associated gene coexpression modules were identified with weighted gene coexpression network analysis (WGCNA), and key module gene functions and the roles of non-malignant cells in PNI were evaluated with a single-cell transcriptomic dataset (GSE103322). Results: PNI was significantly inversely associated with overall survival (HR, 2.08; 95% CI, 1.27 to 3.40; P = 0.004), especially in advanced patients (HR, 2.62; 95% CI, 1.48 to 4.64; P < 0.001). Age, gender, smoking history, and alcohol history were not risk factors. HPV-positive cases were less likely than HPV-negative cases to develop PNI (OR, 0.28; 95% CI, 0.09 to 0.76; P = 0.017). WGCNA identified a unique significantly PNI-associated coexpression module containing 357 genes, with 12 hub genes (TIMP2, MIR198, LAMA4, FAM198B, MIR4649, COL5A1, COL1A2, OLFML2B, MMP2, FBN1, ADAM12, and PDGFRB). Single-cell transcriptomic data analysis revealed that the genes in the PNI-associated module correlated with the signatures “EMT,” “metastasis,” and “invasion.” Among non-malignant cells, fibroblasts had relatively high expression of the key genes. Conclusion: At the molecular and omic levels, we verified that PNI in HNSCC is a process of invasion rather than simple diffusion. Fibroblasts probably play an important role in PNI. Novelty & Impact Statements The study is a thorough analysis of PNI in HNSCC from the clinical level to the molecular level and presents the first description of cancer-related PNI from the omics perspective to date as far as we know. We verified that PNI in HNSCC is a process of invasion rather than simple diffusion, at the molecular and omic levels. Fibroblasts were found to probably play an important role in PNI by analyzing single-cell transcriptomic data.

The DNA base excision repair gene APE1 involves in DNA damage repair pathway and overexpression in a variety of human cancers. Analyses of patients with non-small cell lung cancer (NSCLC) suggested that multiple factors associated with prognosis of NSCLC patients. Further investigation showed that APE1 expression was able to predict the progression-free survival and overall survival in patients with NSCLC and correlated with lymph node metastasis. Intriguingly, as a stratification of APE1-141 SNPs in APE1 positive expression, we also found APE1-141 GT/GG was identified as a marker for prediction of poor survival in NSCLC patients. In the in vitro experiments, the results showed that when APE1 expression was inhibited by siRNA or AT101 (an APE1 inhibitor), the migration and invasion of NSCLC cells were suppressed. Furthermore, epithelial-mesenchymal transition (EMT) markers was tested to provide evidence that APE1 promoted NSCLC EMT through interaction with SirT1. Using NSCLC xenograft models, we confirmed that AT101 shrank tumor volumes and inhibited lymph node metastasis. In conclusion, APE1 could be a potential target for patients with NSCLC metastasis and AT101 is a potent inhibitor in further treatment of NSCLC patients.

We previously reported that cetuximab, an EGFR-blocking antibody, inhibits cancer metabolism via downregulation of HIF-1α and reverses the Warburg effect in cancer cells. Here, we report that inhibition of HIF-1 transcriptional activity by cetuximab does not necessarily lead to successful inhibition of cell proliferation. In several head and neck squamous cell carcinoma (HNSCC) cell lines, we observed a pattern of oscillating decrease and increase of intracellular ATP level after cetuximab treatment, and the magnitude and kinetics of which varied by cell line and appeared to be linked to the extent of cellular response to cetuximab. In HNSCC cells with low basal level of AMPK activity and that responded to cetuximab-induced growth inhibition, there was a transient, LKB1-dependent activation of AMPK. In contrast, HNSCC cells that had a high basal level of AMPK activity were less sensitive to cetuximab-induced growth inhibition despite effective inhibition of EGFR downstream signaling by cetuximab. Knockdown or inhibition of AMPK markedly enhanced response to cetuximab via induction of apoptosis. These findings indicate that a transient activation of AMPK is an early metabolic marker of cellular response to cetuximab and that high and sustained AMPK activity is an important mechanism by which cancer cells survive cetuximab treatment.

Unlike normal cells, cancer cells are recently identified to rely on aerobic glycolysis for energy production called the Warburg effect. Several attempts are being made to target this metabolic reprogramming pathway in treating cancers; however, the successful rate is very limited. In this study, we investigated the functional roles of fatty acid oxidation key enzyme carnitine palmitoyl transferase 1a (CPT-1a), during the metabolic programming of pancreatic ductal adenocarcinoma (PDAC) cells induced by glucose deprivation. Knockdown of CPT-1a decreased the intracellular nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH) generation, increased reactive oxygen species (ROS) production, and induced sensitivity to glucose deprivation, whereas upregulation of CPT-1a increased the intracellular ATP required for cell survival. Further investigation showed that CPT-1a inhibitor etomoxir (ETO) can restore the sensitivity of PDAC cells to gemcitabine and regress xenograft tumors in vivo. Finally, overexpression of CPT-1a expression is associated with chemoresistance in tumor specimens. Our data suggest that CPT-1a plays a key role in reprogramming cancer metabolism to escape from energy stress.

Introduction: Aberrant activation of Semaphorin3C(SEMA3C) is widespread in human cancers. We aimed to analyze SEMA3C expression in cervical cancer and investigate the role of SEMA3C in cervical cancer and its underlying mechanism, which is important for exploring new therapeutic targets and prognostic factors.Materials and Methods: The expression of SEMA3C was examined in paraffin-embedded cervical cancer specimens. In vivo and in vitro assays were performed to validate the effect of SEMA3C on cervical cancer cell proliferation and p-ERK pathway activation. Gene Set Enrichment Analysis (GSEA) was performed using The Cancer Genome Atlas (TCGA) data set.Results: SEMA3C expression was associated with poor survival in both the TCGA cohort and our cohort. Silencing of SEMA3C suppressed cervical cancer cell proliferation, colony formation ability, and the activation of the p-ERK signaling pathway in vitro. SEMA3C depletion inhibited tumor growth in vitro. GSEA also showed that the epithelial mesenchymal transition (EMT), TGFβ signaling pathway, angiogenesis, and extracellular matrix (ECM) receptor interactions are associated with a high SEMA3C expression phenotype.Conclusion: SEMA3C is correlated with poor prognosis of cervical cancer patients and promotes tumor growth via the activation of the p-ERK pathway.

Breast cancer anti-estrogen resistance protein 3 (BCAR3) is involved in anti-estrogen resistance and other important aspects of breast cancer. However, the role of BCAR3 in other solid tumors remains unclear. The relationship between the clinicopathologic characteristics of head and neck squamous cell carcinoma (HNSCC) patients and BCAR3 was analyzed using the Wilcoxon’s signed-rank test and logistic regression. The association between BCAR3 expression and clinicopathologic features and survival was analyzed using Cox regression and the Kaplan–Meier method. In vivo and in vitro assays were performed to validate the effect of BCAR3 on HNSCC growth. BCAR3-related mRNAs were determined by calculating the Pearson’s correlation coefficient based on The Cancer Genome Atlas (TCGA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and gene set enrichment analysis (GSEA) were used to predict the potential functions of BCAR3. BCAR3 expression is overexpressed in HNSCC and was shown to be associated with perineural invasion (PNI) and poor survival. BCAR3 silencing significantly attenuated the proliferation of HNSCC cells, whereas BCAR3 depletion inhibited tumor growth in vitro. GO and KEGG functional enrichment analyses, and GSEA showed that BCAR3 expression in HNSCC was associated with biological processes, such as cell adhesion, actin binding, cadherin binding, and angiogenesis. BCAR3, which promotes HNSCC growth, is associated with perineural invasion and may be a potential molecular prognostic marker of poor survival in HNSCC.