Author response: YAP1 activation by human papillomavirus E7 promotes basal cell identity in squamous epithelia
Year: 2022
Type: peer-review
Abstract: Article Figures and data Abstract Editor's evaluation eLife digest Introduction Results Discussion Materials and methods Data availability References Decision letter Author response Article and author information Metrics Abstract Persistent human papillomavirus (HPV) infection of stratified squamous epithelial cells causes nearly 5% of cancer cases worldwide. HPV-positive oropharyngeal cancers harbor few mutations in the Hippo signaling pathway compared to HPV-negative cancers at the same anatomical site, prompting the hypothesis that an HPV-encoded protein inactivates the Hippo pathway and activates the Hippo effector yes-associated protein (YAP1). The HPV E7 oncoprotein is required for HPV infection and for HPV-mediated oncogenic transformation. We investigated the effects of HPV oncoproteins on YAP1 and found that E7 activates YAP1, promoting YAP1 nuclear localization in basal epithelial cells. YAP1 activation by HPV E7 required that E7 binds and degrades the tumor suppressor protein tyrosine phosphatase non-receptor type 14 (PTPN14). E7 required YAP1 transcriptional activity to extend the lifespan of primary keratinocytes, indicating that YAP1 activation contributes to E7 carcinogenic activity. Maintaining infection in basal cells is critical for HPV persistence, and here we demonstrate that YAP1 activation causes HPV E7 expressing cells to be retained in the basal compartment of stratified epithelia. We propose that YAP1 activation resulting from PTPN14 inactivation is an essential, targetable activity of the HPV E7 oncoprotein relevant to HPV infection and carcinogenesis. Editor's evaluation The oncogenic virus Human Papillomavirus encodes the E7 protein which is an important contributor to carcinogenesis. The authors of this publication discovered a novel function of HPV E7, that contributes to its carcinogenic properties. They show that the ability of E7 to extend the lifespan of keratinocytes and facilitate basal cell retention are both activities mediated by the basal-cell specific activation of the cellular protein YAP1. https://doi.org/10.7554/eLife.75466.sa0 Decision letter Reviews on Sciety eLife's review process eLife digest The ‘epithelial’ cells that cover our bodies are in a constant state of turnover. Every few weeks, the outermost layers die and are replaced by new cells from the layers below. For scientists, this raises a difficult question. Cells infected by human papillomaviruses, often known as HPV, can become cancerous over years or even decades. How do infected cells survive while the healthy cells around them mature and get replaced? One clue could lie in PTPN14, a human protein which many papillomaviruses eliminate using their viral E7 protein; this mechanism could be essential for the virus to replicate and cause cancer. To find out the impact of losing PTPN14, Hatterschide et al. used human epithelial cells to make three-dimensional models of infected tissues. These experiments showed that, when papillomaviruses destroy PTPN14, a human protein called YAP1 turns on in the lowest, most long-lived layer of the tissue. Cells in which YAP1 is activated survive while those that carry the inactive version mature and die. This suggests that papillomaviruses turn on YAP1 to remain in tissues for long periods. Papillomaviruses cause about five percent of all human cancers. Finding ways to stop them from activating YAP1 has the potential to prevent disease. Overall, the research by Hatterschide et al. also sheds light on other epithelial cancers which are not caused by viruses. Introduction Human papillomaviruses (HPV) are nonenveloped viruses with circular double-stranded DNA genomes that infect keratinocytes in stratified squamous epithelia (Doorbar et al., 2015; Graham, 2017; McBride, 2017). Although most HPV infections are cleared by the immune system, some infections persist and form higher grade lesions that can lead to cancer (Koshiol et al., 2008; McBride, 2022; Radley et al., 2016; Rositch et al., 2013). HPV infection at mucosal epithelial sites causes cancers including oropharyngeal, cervical, vaginal, penile, and anal malignancies (de Martel et al., 2017; Gillison et al., 2015). Nearly 5% of human cancer cases are caused by persistent infection with one of the high-risk (oncogenic) HPV genotypes (de Martel et al., 2020). Inactivation of host cell tumor suppressors by the high-risk HPV E6 and E7 oncoproteins modulates cellular processes that enable HPV persistence. Two well-characterized instances of tumor suppressor inactivation by HPV are high-risk HPV E6 proteins targeting p53 for proteasome-mediated degradation and high-risk HPV E7 proteins binding and degrading the retinoblastoma protein (RB1) (Heck et al., 1992; Münger et al., 1989; Scheffner et al., 1990; Werness et al., 1990). Both p53 degradation and RB1 inactivation are required for productive HPV infection (Collins et al., 2005; Flores et al., 2000; Kho et al., 2013; McLaughlin-Drubin et al., 2005; Wang et al., 2009). In addition to supporting productive infection, E7 is essential for HPV-mediated carcinogenesis (Mirabello et al., 2017). The impact of the HPV oncoproteins on cell growth control pathways is reflected in human cancer genomic data: genes in the p53 pathway and in the RB1-related cell cycle pathway are frequently mutated in HPV-negative head and neck squamous cell carcinoma (HNSCC) but infrequently mutated in HPV-positive HNSCC (Sanchez-Vega et al., 2018). Although some of the growth-promoting activities of high-risk HPV E6 and E7 are well established, open questions remain. RB1 binding/degradation by high-risk HPV E7 is necessary but insufficient for E7 transforming activity (Balsitis et al., 2006; Balsitis et al., 2005; Banks et al., 1990; Ciccolini et al., 1994; Helt and Galloway, 2001; Huh et al., 2005; Ibaraki et al., 1993; Jewers et al., 1992; Phelps et al., 1992; Strati and Lambert, 2007; White et al., 2015). Papillomavirus researchers have sought to identify one or more activities of HPV E7 that cooperate with RB1 inactivation to promote carcinogenesis and to identify the cellular pathway affected by such an activity. Human cancer genomic data indicates that like the p53 and cell cycle pathways, the Hippo signaling pathway is more frequently mutated in HPV-negative than in HPV-positive HNSCC. The core Hippo pathway consists of a kinase cascade upstream of the effector proteins yes-associated protein (YAP1) and its paralog transcriptional coactivator with PDZ binding motif (TAZ). When the Hippo kinases are inactive, YAP1 and TAZ are activated and translocate to the nucleus. In stratified squamous epithelia, YAP1 is primarily expressed in the basal layer, where YAP1 activation is regulated by contextual cues including cell density, tension in the extracellular matrix, and contact with the basement membrane (Elbediwy et al., 2016; Totaro et al., 2017; Zhang et al., 2011). In normal stratified squamous epithelia, activation of YAP1 and TAZ promotes expansion of the basal cell compartment and inhibition of YAP1 and TAZ allows keratinocytes to differentiate (Beverdam et al., 2013; Elbediwy and Thompson, 2018; Schlegelmilch et al., 2011; Totaro et al., 2017; Yuan et al., 2020; Zhang et al., 2011). Mutations in many of the tumor suppressors upstream of YAP1/TAZ are common in a variety of cancer types (Moroishi et al., 2015). Protein tyrosine phosphatase non-receptor type 14 (PTPN14) has been implicated as a tumor suppressor and negative regulator of YAP1 (Knight et al., 2018; Mello et al., 2017; Poernbacher et al., 2012; Wang et al., 2012). E7 proteins from diverse HPV genotypes bind directly to PTPN14 and recruit the E3 ligase UBR4 to direct PTPN14 for proteasome-mediated degradation (Szalmás et al., 2017; White et al., 2016; White et al., 2012b; Yun et al., 2019). We have shown that PTPN14 degradation and RB1 binding/degradation are separable activities of HPV E7 that each contributes to E7 carcinogenic activity (Hatterschide et al., 2020; Hatterschide et al., 2019; White et al., 2016). However, the downstream consequences of PTPN14 degradation are poorly understood, and so far we have not observed that PTPN14 inactivation in human keratinocytes causes an increase in canonical YAP1 target genes CTGF and CYR61. These observations regarding an additional transforming activity of HPV E7, the ability of E7 to inactivate PTPN14, and the relative paucity of mutations in the Hippo pathway in HPV-positive HNSCC led us to hypothesize that HPV E7-mediated activation of YAP1 is required for the transforming activity of high-risk HPV E7. Here we show that expression of high-risk HPV E7 is sufficient to activate YAP1 and that HPV E7 requires YAP1/TAZ-TEAD transcriptional activity to promote cell growth. We demonstrate that HPV E7 must bind PTPN14 to activate YAP1 and that PTPN14 inactivation alone is sufficient to activate YAP1. YAP1 activation by HPV E7 is restricted to the basal layer of the epithelium where we found PTPN14 expression to be enriched. Our finding that either HPV E7 or PTPN14 loss activated YAP1 specifically in basal epithelial cells led us to investigate the role of YAP1 activation during normal HPV infection. HPV infection begins in basal epithelial keratinocytes (Day and Schelhaas, 2014; Pyeon et al., 2009; Roberts et al., 2007) and infected basal cells are the site of persistent HPV infection (Doorbar et al., 2021). The basal cell compartment contains the only long-lived cells in the epithelium and the HPV genome can be maintained in dividing cells in a largely dormant state (Egawa et al., 2012; Parish et al., 2006; You et al., 2004). Activation of YAP1 and TAZ has been proposed to maintain the progenitor cell state in several different epithelia (Beverdam et al., 2013; Heng et al., 2020; Hicks-Berthet et al., 2021; Szymaniak et al., 2015; Yimlamai et al., 2014; Zhao et al., 2014). If YAP1 activation by E7 promotes the maintenance of a basal cell state in stratified squamous epithelia, YAP1 activation could facilitate the persistence of HPV-positive cells. Testing this hypothesis, we found that YAP1 activation and PTPN14 degradation by E7 both promote the maintenance of cells in the basal compartment of stratified epithelia. We propose that YAP1 activation facilitates HPV persistence and contributes to the carcinogenic activity of high-risk HPV E7. Results HPV E7 activates YAP1 in basal keratinocytes A comprehensive analysis of somatic mutations and copy number variations in human tumor samples revealed that the cell cycle, p53, and Hippo pathways are the three pathways that exhibit the greatest difference in alteration frequency in HPV-negative vs HPV-positive HNSCC (Sanchez-Vega et al., 2018). We used data made available by The Cancer Genome Atlas (TCGA) through cBioPortal (Lawrence et al., 2015) to recapitulate the finding that genes in these pathways are altered at a lower frequency in HPV-positive than in HPV-negative HNSCC (Figure 1A and Figure 1—figure supplement 1). However, most HPV-positive HNSCC arise in the oropharynx. We repeated the analysis of pathway alteration rates using data only from HPV-positive and HPV-negative oropharyngeal squamous cell carcinomas (OPSCC) (Figure 1A and Figure 1—figure supplement 1). Consistent with previous findings, HPV-negative OPSCC were more frequently altered in the p53, cell cycle, and Hippo pathways than HPV-positive OPSCC. Hippo pathway alterations in HPV-negative HNSCC or OPSCC include amplification of the YAP1/TAZ oncogenes or inactivating mutations in one or more of the upstream inhibitors of YAP1/TAZ, including PTPN14. Either alteration type is consistent with a carcinogenic role for YAP1 activation in HNSCC. Figure 1 with 5 supplements see all Download asset Open asset Human papillomavirus (HPV) E7 activates yes-associated protein (YAP1) in basal epithelial keratinocytes. (A) cBioPortal analysis for total genomic mutations and copy number alterations in HPV-positive and HPV-negative oropharyngeal squamous cell carcinoma (OPSCC) and head and neck squamous cell carcinoma (HNSCC). Graph displays the percent of tumors with alterations in each pathway. Statistical significance was determined by Fisher’s exact test (**p<0.01, ****p<0.0001). (B–D) Organotypic cultures were grown from primary human foreskin keratinocytes (HFK), HFK harboring the HPV18 genome, or HFK transduced with retroviral expression vectors encoding HPV E6 or E7 proteins. Formalin-fixed paraffin-embedded sections of cultures grown from (B) HFK or HFK harboring the HPV18 genome, (C) HFK or HFK expressing HPV16 E7 or HPV18 E7, or (D) HFK or HFK expressing HPV16 E6 or HPV16 E7 were stained for YAP1 (magenta), proliferating cell nuclear antigen (PCNA) (green), and Hoechst (gray). White dashed lines indicate the basement membrane. White boxes indicate the location of insets in main images. Main image scale bars = 100 μm. Inset scale bars = 25 μm. To test whether an HPV-encoded protein activates YAP1, we grew three dimensional (3D) organotypic epithelial cultures to model the differentiation of keratinocytes into basal and suprabasal compartments. Organotypic cultures of primary human foreskin keratinocytes (HFK) harboring an HPV18 genome exhibited increased YAP1 staining and increased YAP1 nuclear localization, indicative of YAP1 activation, in the basal layer of the epithelium compared to HFK cultures (Figure 1B and Figure 1—figure supplement 2A-E). Proliferating cell nuclear antigen (PCNA) transcription increases upon RB1 inactivation and is a marker of HPV E7 expression (Cheng et al., 1995; Flores et al., 2000; Lee et al., 1995). Although YAP1 activation in the HPV18 genome containing cells was restricted to the basal cells, PCNA levels were elevated in both the basal and suprabasal layers of the epithelium in the same cultures. We next tested whether either high-risk HPV E6 or E7 alone was sufficient to activate YAP1. HFK transduced with retroviral expression vectors encoding HPV16 E6, HPV16 E7, or HPV18 E7 were used to grow organotypic cultures. YAP1 expression and nuclear localization were increased in the HPV16 E7 and HPV18 E7 expressing cells relative to parental HFK (Figure 1C, Figure 1—figure supplement 3A-C, and Figure 1—figure supplement 5A-C). Similar to our observation in the HPV18 genome-containing cells, YAP1 activation was restricted to the basal epithelial layer. YAP1 nuclear localization increased modestly in organotypic cultures of HPV16 E6 expressing cells (Figure 1D, Figure 1—figure supplement 4, and Figure 1—figure supplement 5A-C). Constitutive expression of either HPV16 E7 or HPV18 E7 induced PCNA expression in basal and suprabasal cells. We conclude that HPV promotes increased YAP1 expression and nuclear localization in basal keratinocytes and that E7 is sufficient for YAP1 activation. HPV E7 activates YAP1 in keratinocytes through PTPN14 degradation We previously discovered that HPV E7 binds and targets the YAP1 inhibitor PTPN14 for proteasome-mediated degradation (White et al., 2016; White et al., 2012b). We tested whether loss of PTPN14 expression in keratinocytes was sufficient to activate YAP1 in stratified epithelia by growing 3D organotypic cultures from existing control and PTPN14 knockout (KO) N/Tert-Cas9 keratinocytes (sgPTPN14) (Hatterschide et al., 2019). We found that YAP1 levels and YAP1 nuclear localization were increased in PTPN14 KO cultures compared to controls (Figure 2A and Figure 2—figure supplement 1A-F). YAP1 activation in basal epithelial cells lacking PTPN14 was comparable to YAP1 activation in HPV E7 cells. We conclude that loss of PTPN14 expression activates YAP1 in basal keratinocytes. Figure 2 with 2 supplements see all Download asset Open asset Human papillomavirus (HPV) E7 activates yes-associated protein (YAP1) in basal keratinocytes through protein tyrosine phosphatase non-receptor type 14 (PTPN14) degradation. Organotypic cultures were grown from N/Tert-Cas9 keratinocytes transfected with sgRNA or from primary human foreskin keratinocytes (HFK) transduced with retroviral expression vectors encoding HPV18 E7 WT or R84S. (A) Formalin-fixed paraffin-embedded (FFPE) sections of cultures grown from mock or sgPTPN14 transfected N/Tert-Cas9 keratinocytes were stained for YAP1 (magenta), involucrin (IVL) (green), and Hoechst (gray). (B) FFPE sections of cultures grown from parental HFK, HPV18 E7 WT, or HPV18 E7 R84S expressing HFK were stained for YAP1 (magenta), proliferating cell nuclear antigen (PCNA) (green), and Hoechst (gray). White dashed lines indicate the basement membrane. White boxes indicate the location of insets in main images. Main image scale bars = 100 μm. Inset scale bars = 25 μm. (C–F) Quantification of the number of (C and D) basal cells and (E and F) suprabasal cells per 100 μm of epidermis. Graphs display the mean ± SD and each individual data point (independent organotypic cultures). (C and E) Statistical significance was determined by t-test. (D and F) Statistical significance was determined by ANOVA using the Holm-Sídák correction for multiple comparisons (*p<0.05, ***p<0.001). A highly conserved C-terminal arginine in E7 makes a direct interaction with the C-terminus of PTPN14 and the HPV18 E7 R84S variant is unable to bind or degrade PTPN14 (Hatterschide et al., 2020; Yun et al., 2019). To test whether PTPN14 degradation by HPV E7 is required for activation of YAP1, we grew 3D organotypic cultures using primary HFK transduced with retroviral expression vectors encoding HPV18 E7 wild type (WT) or HPV18 E7 R84S. Indeed, YAP1 expression and nuclear localization in the basal layer of HPV18 E7 R84S cultures were reduced compared to HPV18 E7 WT controls (Figure 2B, Figure 1—figure supplement 5A-C, and Figure 2—figure supplement 2). In addition to activating YAP1, PTPN14 loss increased basal cell density from an average of 5.5 cells per 100 μm in control cultures to 9.0 cells per 100 μm in PTPN14 KO cultures (Figure 2C). Basal cell density was higher in HPV18 E7 WT cultures (9.4 cells per 100 μm) than in HPV18 E7 R84S cultures (7.1 cells per 100 μm) (Figure 2D). No statistically significant difference in suprabasal cell density was observed in either comparison (Figure 2E and F). We conclude that E7 expression or PTPN14 loss in stratified squamous epithelia is sufficient to activate YAP1 in the basal layer of the epithelium and increase basal cell density. PTPN14 expression is enriched in basal keratinocytes YAP1 activation was restricted to basal epithelial cells in our organotypic cultures, leading us to hypothesize that PTPN14 may act as a basal layer specific inhibitor of YAP1. We therefore sought to determine whether PTPN14 expression is restricted to a specific subset of cells in the stratified epithelium. In a recent single-cell RNA sequencing analysis of human neonatal foreskin epidermis, PTPN14 mRNA expression was enriched in the basal-III cluster (Figure 3A and B; Wang et al., 2020a). The basal-III cell cluster was described to be nonproliferating, marked by COL17A1 expression, and predicted to differentiate directly into spinous cells based on pseudotime analysis. PTPN14 expression was higher in basal-III cells than in the spinous or granular cell clusters. To measure PTPN14 expression in basal and suprabasal cells in our cultures, we used laser capture microdissection to isolate basal and suprabasal layers from 3D organotypic cultures grown from unmodified primary HFK (Figure 3C). We found that there was an approximately fivefold enrichment of PTPN14 mRNA in the basal epithelial layer compared to the suprabasal layers (Figure 3D). As expected, the basal integrins ITGA6 and ITGB4 were expressed in the basal layer (Figure 3E) and the differentiation markers KRT1 and IVL were expressed in the suprabasal layers (Figure 3F). The same pattern of PTPN14 mRNA expression was observed in an organotypic culture grown from primary HFK expressing HPV18 E7 WT (Figure 3—figure supplement 1A-C). We conclude that PTPN14 mRNA is enriched in basal keratinocytes in the presence or absence of HPV E7. Our data support that PTPN14 acts as a YAP1 inhibitor specifically in the basal compartment of stratified epithelia. Figure 3 with 1 supplement see all Download asset Open asset Protein tyrosine phosphatase non-receptor type 14 (PTPN14) expression is enriched in basal keratinocytes. (A–B) Single-cell RNA sequencing data and clustering analysis from Wang et al. was reanalyzed to assess PTPN14 expression in different subsets of epidermal cells. (A) Diagram of epidermis; shading depicts tissue localization of cell clusters. (B) For each donor, the mean of PTPN14 mRNA expression was calculated for each cell cluster. Graphs display the mean of PTPN14 mRNA expression for each donor (circles) as well as the mean of all five donors ± SEM (bars and error bars). Statistical significance was determined by ANOVA using the Holm-Sídák correction for multiple comparisons (*p<0.05, **p<0.01). (C–F) Basal and suprabasal layers from organotypic cultures were dissected using laser capture microdissection. (C) Representative images of HFK cultures before and after individual laser dissections. Hundreds of such cuts were performed per sample. (D–F) RNA was purified from isolated layers and qRT-PCR was used to assess the expression of PTPN14 (D), basal cell markers ITGA6 and ITGB4 (E), and differentiation markers KRT1 and IVL (F). Graphs display the mean and each individual data point. YAP1/TAZ regulate differentiation downstream of PTPN14 In previous unbiased experiments we found that the primary effect of PTPN14 inactivation on transcription is to repress epithelial differentiation gene expression (Hatterschide et al., 2020; Hatterschide et al., 2019). However, we also observed that PTPN14 inactivation did not increase expression of the canonical YAP1/TAZ targets CTGF and CYR61. Consistent with this difference there was minimal overlap between PTPN14-dependent differentially expressed genes and the genes listed in the MSigDB conserved YAP1 signature (Figure 4A). We therefore asked whether the ability of PTPN14 to regulate differentiation gene expression requires YAP1/TAZ as intermediates. Transduction of keratinocytes with a PTPN14 lentivirus induced the expression of the differentiation markers KRT10 and IVL in a dose-dependent manner (Figure 4—figure supplement 1A-C). To test whether PTPN14 required YAP1/TAZ to increase differentiation marker gene expression, we transfected HFK with siRNAs targeting YAP1 and WWTR1 (the gene encoding TAZ) then transduced the cells with PTPN14 lentivirus (Figure 4B). HFK transfected with control siRNA exhibited the expected increase in KRT1 and IVL after transduction with PTPN14 lentivirus (Figure 4C and D and Figure 4—figure supplement 2A,B). However, keratinocytes depleted of YAP1/TAZ did not express relatively more KRT1 or IVL when PTPN14 was overexpressed than when it was not. We conclude that PTPN14 requires YAP1 and/or TAZ to regulate differentiation gene expression in keratinocytes. Both pairs of YAP1/TAZ siRNA had the same effect on differentiation in response to PTPN14 overexpression yet only one pair depleted TAZ protein levels (Figure leading us to that YAP1 is the PTPN14 levels to differentiation gene Figure with 2 supplements see all Download asset Open asset protein regulate differentiation downstream of protein tyrosine phosphatase non-receptor type 14 (PTPN14). (A) the MSigDB conserved signature to the differentially expressed genes from our experiments that PTPN14 loss in keratinocytes. (B–D) YAP1 and WWTR1 were by siRNA in human foreskin keratinocytes HFK were then transduced with PTPN14 lentivirus at Cells were for protein and total cellular RNA at (B) were to analysis and with to PTPN14, YAP1, and (Figure data 1). TAZ was by the membrane that was for YAP1. (C and D) qRT-PCR was used to measure the expression of the differentiation markers KRT1 and IVL relative to Graphs display in gene expression relative to the mock transduced cells. HFK were transfected with siRNAs targeting YAP1, WWTR1 PTPN14, and Two siRNAs were used per qRT-PCR was used to measure gene expression the differentiation markers IVL and KRT1 and the canonical YAP1/TAZ targets CTGF and Data that individual siRNA depleted are in a of levels display the mean ± SD of three Statistical significance of each compared to was determined by ANOVA using the Holm-Sídák correction for multiple comparisons (*p<0.05, ****p<0.0001). Figure data 1 images for in Figure images from YAP1, and in Figure are as individual image and as a Download we tested whether of differentiation upon loss of and the core Hippo pathway kinases that and YAP1 and We used siRNAs to PTPN14, or and the expression of the differentiation markers KRT1 and IVL (Figure and F). of PTPN14, or all differentiation gene expression to a of the three affected the levels of CTGF or (Figure of YAP1 or WWTR1 affected both differentiation gene expression and than all siRNAs used in these experiments reduced the expression of their target genes by or (Figure YAP1 had a effect than did WWTR1 and our qRT-PCR that WWTR1 levels were in This that inactivation of three different YAP1 inhibitors differentiation gene expression even in the absence of a differentiation and not increase canonical YAP1 target gene expression in keratinocytes. We have previously observed that PTPN14 knockout or E7 expression differentiation gene expression both in cells and in cells to differentiate (Hatterschide et al., 2020; Hatterschide et al., 2019). these data support that PTPN14 promotes differentiation through inhibition of YAP1/TAZ not canonical YAP1/TAZ target HPV-positive HNSCC are than HPV-negative HNSCC We next asked whether the gene expression pattern observed downstream of PTPN14 loss is reflected in HPV-positive cancers. HPV-positive HNSCC have a poorly et al., and which is reflected in their transcriptional (Hatterschide et al., 2019). We the between HPV and of differentiation by analysis of the differentiation marker KRT1 in sections of 14 HPV-negative tumors and HPV-positive tumors (Figure percent of HPV-negative tumors and of HPV-positive tumors stained for We also gene expression in models from human HNSCC. We and IVL levels using RNA from HPV-negative and HPV-positive HNSCC differentiation marker was expressed at a lower in HPV-positive than in HPV-negative (Figure We observed the same pattern of differentiation marker gene expression in an analysis of data from other (Figure supplement et al., 2015). that HPV-positive HNSCC exhibit reduced expression of differentiation markers compared to HPV-negative we CTGF and We found significant difference in expression of these canonical YAP1/TAZ target genes in HPV-positive vs HPV-negative there was a higher CTGF in the HPV-positive (Figure In the CTGF and expression higher in the HPV-negative HNSCC (Figure supplement The pattern of expression of differentiation markers and canonical YAP1/TAZ target gene expression in HPV-positive HPV-negative samples is consistent with the effects of PTPN14 inactivation in cells. Figure 5 with 1 supplement see all Download asset Open asset Human papillomavirus head and neck squamous cell carcinoma (HNSCC) are than HPV-negative HNSCC. (A) Human HNSCC tumor samples were stained for KRT1 = 100 μm. Graph displays the of tumors that were Statistical significance was determined by Fisher’s exact RNA was purified from samples and qRT-PCR was used to assess gene expression of (B) the differentiation markers and IVL and (C) the canonical yes-associated protein targets CTGF and CYR61. Statistical significance was determined by test (*p<0.05, **p<0.01).
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Institution: University of Pennsylvania
Language: English
Subfield: Cell Biology
Domain: Life Sciences
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