The translational significance of epithelial-mesenchymal transition in head and neck cancer

Cetuximab chemotherapy resistance: Insight into the homeostatic evolution of head and neck cancer (Review)

The complex evolution of genetic alterations in cancer that occurs in vivo is a selective process involving numerous factors and mechanisms. Chemotherapeutic agents that prevent the growth and spread of cancer cells induce selective pressure, leading to rapid artificial selection of resistant subclones. This rapid evolution is possible because antineoplastic drugs promote alterations in tumor‑cell metabolism, thus creating a bottleneck event. The few resistant cells that survive in this new environment obtain differential reproductive success that enables them to pass down the newly selected resistant gene pool. The present review aims to summarize key findings of tumor evolution, epithelial‑mesenchymal transition and resistance to cetuximab therapy in head and neck squamous cell carcinoma.

Human Papillomavirus and Cellular Pathways: Hits and Targets

The Human Papillomavirus (HPV) is the causative agent of different kinds of tumors, including cervical cancers, non-melanoma skin cancers, anogenital cancers, and head and neck cancers. Despite the vaccination campaigns implemented over the last decades, we are far from eradicating HPV-driven malignancies. Moreover, the lack of targeted therapies to tackle HPV-related tumors exacerbates this problem. Biomarkers for early detection of the pathology and more tailored therapeutic approaches are needed, and a complete understanding of HPV-driven tumorigenesis is essential to reach this goal. In this review, we overview the molecular pathways implicated in HPV infection and carcinogenesis, emphasizing the potential targets for new therapeutic strategies as well as new biomarkers.

HPV-inactive cell populations arise from HPV16-transformed human keratinocytes after p53 knockout

HPV-inactive head and neck and cervical cancers contain HPV DNA but do not express HPV E6/E7. HPV-positive primary head and neck tumors usually express E6/E7, however they may produce HPV-inactive metastases. These observations led to our hypothesis that HPV-inactive cancers begin as HPV-active lesions, losing dependence on E6/E7 expression during progression. Because HPV-inactive cervical cancers often have mutated p53, we investigated whether p53 loss may play a role in the genesis of HPV-inactive cancers. p53 knockout (p53-KO) by CRISPR-Cas9 resulted in a 5-fold reduction of E7 mRNA in differentiation-resistant HPV16 immortalized human keratinocytes (HKc/DR). E7 expression was restored by 5-Aza-2 deoxycytidine in p53 KO lines, suggesting a role of DNA methylation in this process. In-situ hybridization showed that p53 KO lines consist of mixed populations of E6/E7-positive and negative cells. Hence, loss of p53 predisposes HPV16 transformed cells to losing dependence on the continuous expression of HPV oncogenes for proliferation.

TGF-β1 induces N-cadherin expression by upregulating Sox9 expression and promoting its nuclear translocation in human oral squamous cell carcinoma cells

Squamous cell carcinoma (SCC) is the most frequent cancer that develops in the oral cavity. Epithelial-mesenchymal transition (EMT) is known to play an important role in the process of metastasis of SCC cells. In our previous study, we demonstrated that TGF-β1 induced EMT in the human oral SCC (hOSCC) cell line HSC-4. We also found that Slug plays an important role in suppressing E-cadherin expression and promotion of the migratory activity of HSC-4 cells. However, we also demonstrated that Slug does not participate in upregulation of N-cadherin expression, suggesting that EMT-related transcription factors other than Slug also play an important role in the process. In the present study, we aimed to elucidate how the transcription factor Sox9 affects the TGF-β1-induced upregulation of N-cadherin expression in HSC-4 cells. We found that TGF-β1 upregulated Sox9 expression in HSC-4 cells. In addition, Sox9 siRNA significantly abrogated the TGF-β1-induced upregulation of N-cadherin expression and inhibited the TGF-β1-promoted migratory activity in HSC-4 cells. We also demonstrated that TGF-β1 upregulated the phosphorylation status of Sox9 and then promoted nuclear translocation of Sox9 from the cytoplasm, possibly resulting in an increase in N-cadherin expression. The cyclic AMP-dependent protein kinase A inhibitor H-89, which is known to suppress phosphorylation of Sox9, significantly abrogated the TGF-β1-induced upregulation of N-cadherin expression. These results suggested that TGF-β1 induced N-cadherin expression by upregulating Sox9 expression and promoting its nuclear translocation, which results in EMT progression in hOSCC cells.

Plasma-derived Exosomes Reverse Epithelial-to-Mesenchymal Transition after Photodynamic Therapy of Patients with Head and Neck Cancer

Photodynamic therapy (PDT) is a palliative treatment option for head and neck squamous cell carcinoma (HNSCC) patients which induces local inflammation and alters tumor cell morphology. We show that exosomes in plasma of HNSCC patients undergoing PDT reprogram tumor cells towards an epithelial phenotype. Nine HNSCC patients were treated with PDT and plasma was collected prior to and at three timepoints after therapy. Exosome levels of E-Cadherin, N-Cadherin and TGF-β1 were tested by flow cytometry. Exosomes were co-incubated with cancer cells, and changes in expression of EMT markers were evaluated as were proliferation, migration, chemotaxis and invasiveness of tumor cells. Exosomes harvested pre- and 24h after PDT were enriched in N-Cadherin and TGF-β1. They induced the mesenchymal phenotype and up-regulated Vimentin and transcripts for Snail, Twist, α-SMA, Slug and ZEB1 in epithelial tumor cells. These exosomes also enhanced tumor proliferation, migration and invasion. In contrast, exosomes obtained on day 7 or 4-6 weeks after PDT carried E-cadherin, restored epithelial morphology and EpCAM expression in tumor cells, down-regulated expression of mesenchymal genes and inhibited proliferation, migration and invasion. The PDT-mediated conversion from the mesenchymal to epithelial tumor phenotype was mediated by exosomes, which also served as non-invasive biomarkers of this transition.

Mouse model of postsurgical primary tumor recurrence and regional lymph node metastasis progression in HPV-related head and neck cancer

HPV-positive head and neck squamous cell carcinoma (HNSCC) is increasingly frequent. Management is particularly debated in the case of postsurgical high-risk features, that is, positive surgical margins and extracapsular spread (ECS). In this increasingly complex emerging framework of HNSCC treatment, representative preclinical models are needed to support future clinical trials and advances in personalized medicine. Here, we present an immunocompetent mouse model based on the implantation of mouse tonsil epithelial HPV16-E6/E7-expressing cancer cells into the submental region of the floor-of-the-mouth. Primary tumors were found to replicate the patterns of human HNSCC local invasion and lymphatic dissemination. To study disease progression after surgery, tumors were removed likely leaving behind residual disease. Surgical resection of tumors was followed by a high rate of local recurrences (>90%) within the first 2-3 weeks. While only 50% of mice had lymph node metastases (LNM) at time of primary tumor excision, all mice with recurrent tumors showed evidence of LNM. To study the consecutive steps of LNM progression and distant metastasis development, LNs from tumor-bearing mice were transplanted into naïve recipient mice. Using this approach, transplanted LNs were found to recapitulate all stages and relevant histological features of regional metastasis progression, including ECS and metastatic spread to the lungs. Altogether, we have developed an immunocompetent HPV-positive HNSCC mouse model of postsurgical local recurrence and regional and distant metastasis progression suitable for preclinical studies.

A wound-healing program is hijacked to promote cancer metastasis

In this issue of JEM, Sundaram et al. (https://doi.org/10.1084/jem.20170354) report a mechanism by which the normal epithelial wound healing response is "hijacked" to promote invasion and metastasis in head and neck squamous carcinomas (HNSCCs), a finding that unveils new markers of poor outcomes and potential targets for therapeutic intervention.

FcGBP was upregulated by HPV infection and correlated to longer survival time of HNSCC patients

FcGBP was normally found in intestinal and colonic epithelia, gallbladder, cystic duct, bronchus, submandibular gland, cervix uteri and in fluids secreted by these cells in humans, and was down-regulated during colon carcinogenesis. We found FcGBP gene expression was decreased in HNSCC tissues compared to surgical safety border tissues while TGF-β expression level increased in HNSCC tissues, and higher FcGBP expression level was correlated to longer OS time of HNSCC patients. FcGBP expression level was higher in HPV-positive HNSCC tissues compared to HPV-negative HNSCC tissues, while TGF-β expression level was lower in HPV-positive HNSCC tissues. Gene expression level of FcGBP and TGF-β was negatively correlated in HNSCC tissues. FcGBP expression level increased after HPV E6 overexpression in HPV-negative HNSCC cells, and TGF-β could inhibit the up-regulation of FcGBP after HPV E6 or FcGBP overexpression in HPV-negative HNSCC cells. The migration capability was inhibited after FcGBP overexpression, and TGF-β could counteract the inhibition of migration caused by FcGBP overexpression. FcGBP gene expression level was correlated to the expression levels of EMT markers. In conclusion, FCGBP expression was upregulated by HPV infection while inhibited by TGF-β, and was correlated to the prognosis of HNSCC patients.

Epithelial to mesenchymal transition and HPV infection in squamous cell oropharyngeal carcinomas: the papillophar study

Background:

Human Papillomavirus (HPV) infection is recognised as aetiological factor of carcinogenesis in oropharyngeal squamous cell carcinomas (OPC). HPV-related OPC respond better to treatments and have a significantly favourable outcome. Epithelial to mesenchymal transition (EMT) implicated in tumour invasion, is a hallmark of a poor prognosis in carcinomas.

Methods:

We have studied the relationship of EMT markers (E-cadherin, β-catenin and vimentin) with HPV infection (DNA and E6/E7 mRNA detection), p16^INK4a expression and survival outcomes in a cohort of 296 patients with OPC.

Results:

Among the 296 OPSSC, 26% were HPV positive, 20.3% had overt EMT (>25% of vimentin positive tumour cells). Lower E-cadherin expression was associated with a higher risk of distant metastasis in univariate (P=0.0110) and multivariate analyses (hazard ratios (HR)=6.86 (1.98; 23.84)). Vimentin expression tends towards worse metastasis-free survival (MFS; HR=2.53 (1.00; 6.41)) and was an independent prognostic factor of progression-free survival (HR=1.55 (1.03; 2.34)).

Conclusions:

There was a non significant association of EMT with HPV status. This may be explained by a mixed subpopulation of patients HPV positive with associated risk factors (HPV, tobacco and alcohol). Thus, the detection of EMT in OPC represents another reliable approach in the prognosis and the management of OPC whatever their HPV status.

Transforming growth factor-β1 suppresses bone morphogenetic protein-2-induced mesenchymal-epithelial transition in HSC-4 human oral squamous cell carcinoma cells via Smad1/5/9 pathway suppression

Squamous cell carcinoma is the most common cancer in the oral cavity. We previously demonstrated that transforming growth factor-β1 (TGF-β1) promotes the epithelial-mesenchymal transition (EMT) of human oral squamous cell carcinoma (hOSCC) cells; however, it remains to be clarified whether the TGF-β superfamily member bone morphogenetic protein (BMP) affects this process in hOSCC cells. Here, we examined the independent and collective effects of TGF-β1 and BMP-2 on EMT and mesenchymal‑epithelial transition (MET) in a panel of four hOSCC cell lines. Notably, we found that HSC-4 cells were the most responsive to BMP-2 stimulation, which resulted in the upregulation of Smad1/5/9 target genes such as the MET inducers ID1 and cytokeratin 9 (CK9). Furthermore, BMP-2 downregulated the mesenchymal marker N-cadherin and the EMT inducer Snail, but upregulated epithelial CK9 expression, indicating that BMP-2 prefers to induce MET rather than EMT. Moreover, TGF-β1 dampened BMP-2-induced epithelial gene expression by inhibiting Smad1/5/9 expression and phosphorylation. Functional analysis revealed that TGF-β1 and BMP-2 significantly enhanced HSC-4 cell migration and proliferation, respectively. Collectively, these data suggest that TGF-β positively regulates hOSCC invasion in the primary tumor, whereas BMP-2 facilitates cancer cell colonization at secondary metastatic sites. Thus, the invasive and metastatic characteristics of hOSCC appear to be reciprocally regulated by BMP and TGF-β.

Targeting roles of inflammatory microenvironment in lung cancer and metastasis

Inflammatory cells and mediators are essential components in tumor microenvironment and play decisive roles in the initiation, proliferation, survival, promotion, invasion, or metastasis of lung cancer. Clinical and epidemiologic studies suggested a strong association between inflammation and lung cancer and an influence of immune surveillances and tumor responses to chemotherapeutic drugs, although roles of inflammation in lung cancer remain unclear. The present review outlined roles of inflammation in lung cancer, with particular focus on inflammatory components, types, biomarkers, or principal mechanisms by which the inflammation contributes to the development of lung cancer. The cancer-associated inflammatory cells (CICs) should be furthermore defined and include cancer-specific and interacted cells with inflammatory or inflammation-like characteristics, e.g., innate or adaptive immune cells and cancer tissue cells. We also discuss targeting potentials of inflammation in the prevention and treatment of lung cancer. The diversity of cancer-related inflammatory microenvironment is instrumental to design novel therapeutic approaches for lung cancer.

Potentials of single-cell biology in identification and validation of disease biomarkers

Single-cell biology is considered a new approach to identify and validate disease-specific biomarkers. However, the concern raised by clinicians is how to apply single-cell measurements for clinical practice, translate the message of single-cell systems biology into clinical phenotype or explain alterations of single-cell gene sequencing and function in patient response to therapies. This study is to address the importance and necessity of single-cell gene sequencing in the identification and development of disease-specific biomarkers, the definition and significance of single-cell biology and single-cell systems biology in the understanding of single-cell full picture, the development and establishment of whole-cell models in the validation of targeted biological function and the figure and meaning of single-molecule imaging in single cell to trace intra-single-cell molecule expression, signal, interaction and location. We headline the important role of single-cell biology in the discovery and development of disease-specific biomarkers with a special emphasis on understanding single-cell biological functions, e.g. mechanical phenotypes, single-cell biology, heterogeneity and organization of genome function. We have reason to believe that such multi-dimensional, multi-layer, multi-crossing and stereoscopic single-cell biology definitely benefits the discovery and development of disease-specific biomarkers.

Transforming growth factor-β1 induces invasion ability of HSC-4 human oral squamous cell carcinoma cells through the Slug/Wnt-5b/MMP-10 signalling axis

Molecular mechanism underlying the invasion of oral cancer cells remains to be clarified. We previously demonstrated that transforming growth factor-β1 (TGF-β1) induces the expression of mesenchymal markers in human oral squamous cell carcinoma HSC-4 cells. Intriguingly, the expression of the epithelial-mesenchymal transition-related transcription factor Slug was also significantly upregulated upon TGF-β1 stimulation. However, the mechanism by which Slug transduces the TGF-β1-induced signal to enhance the invasiveness of HSC-4 cells is poorly understood. Proteomic analysis revealed that the expression of matrix metalloproteinase (MMP)-10 was upregulated in TGF-β1-stimulated cells. Additionally, a Boyden chamber assay revealed that the TGF-β1-induced increase in invasiveness of HSC-4 cells was significantly inhibited by MMP-10 small interfering RNA (siRNA). Intriguingly, Slug siRNA suppressed TGF-β1-induced expression of MMP-10. These results suggest that TGF-β1 induces invasion in HSC-4 cells through the upregulation of MMP-10 expression in a Slug-dependent manner. On the other hand, Slug siRNA suppressed TGF-β1-induced Wnt-5b expression. Wnt-5b significantly induced MMP-10 expression, whereas Wnt-5b siRNA suppressed the TGF-β1-induced increase in invasiveness, suggesting that TGF-β1-induced expression of MMP-10 and the resulting upregulation of invasiveness are mediated by Wnt-5b. Overall, these results suggest that TGF-β1 stimulates HSC-4 cell invasion through the Slug/Wnt-5b/MMP-10 signalling axis.

HPV-p53-miR-34a axis in HPV-associated cancers

Human papillomaviruses (HPVs) are known to cause many cancers by altering multiple signalling pathways through their oncogene integration into host genome and expression. Studies have shown that many microRNAs (miRs) may function as oncogenes (called as oncomiRs) to promote an oncogenic effect. MiR-34a among the reported oncomiRs is a key player in the carcinogenesis caused by infection with HPVs. In this mini-review, we summarise the roles of miR-34a in HPV-caused cancers. MiR-34a is transcriptionally regulated by tumour suppressor p53. HPV oncogene E6 inhibits expression of p53 to decrease the levels of miR-34a, leading to the increased expression of multiple genes which are targeted by miR-34a. The upregulation of these genes increases cancer cell proliferation, survival and migration in HPV-associated cancers.

Global comparison of chromosome X genes of pulmonary telocytes with mesenchymal stem cells, fibroblasts, alveolar type II cells, airway epithelial cells, and lymphocytes

Background

Telocytes (TCs) are suggested as a new type of interstitial cells with specific telopodes. Our previous study evidenced that TCs differed from fibroblasts and stem cells at the aspect of gene expression profiles. The present study aims to search the characters and patterns of chromosome X genes of TC-specific or TC-dominated gene profiles and fingerprints, investigate the network of principle genes, and explore potential functional association.

Methods

We compared gene expression profiles in chromosome X of pulmonary TCs with mesenchymal stem cells (MSC), fibroblasts (Fb), alveolar type II cells (ATII), airway basal cells (ABC), proximal airway cells (PAC), CD8⁺ T cells come from bronchial lymph nodes (T-BL), or CD8⁺ T cells from lungs (T-L) by global analyses, and selected the genes which were consistently up or down regulated (>1 fold) in TCs compared to other cells as TC-specific genes. The functional and characteristic networks were identified and compared by bioinformatics tools.

Results

We selected 31 chromosome X genes as the TC-specific or dominated genes, among which 8 up-regulated (Flna, Msn, Cfp, Col4a5, Mum1l1, Rnf128, Syn1, and Srpx2) and 23 down-regulated (Abcb7, Atf1, Ddx26b, Drp2, Fam122b, Gyk, Irak1, Lamp2, Mecp2, Ndufb11, Ogt, Pdha1, Pola1, Rab9, Rbmx2, Rhox9, Thoc2, Vbp1, Dkc1, Nkrf, Piga, Tmlhe and Tsr2), as compared with other cells.

Conclusions

Our data suggested that gene expressions of chromosome X in TCs are different with those in other cells in the lung tissue. According to the selected TC-specific genes, we infer that pulmonary TCs function as modulators which may enhance cellular growth and migration, resist senescence, protect cells from external stress, regulate immune responses, participate in tissue remodeling and repair, regulate neural function, and promote vessel formation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0669-8) contains supplementary material, which is available to authorized users.