Transcriptomic profiling and quantitative high-throughput (qHTS) drug screening of CDH1 deficient hereditary diffuse gastric cancer (HDGC) cells identify treatment leads for familial gastric cancer

BACKGROUND

Patients with hereditary diffuse gastric cancer (HDGC), a cancer predisposition syndrome associated with germline mutations of the CDH1 (E-cadherin) gene, have few effective treatment options. Despite marked differences in natural history, histopathology, and genetic profile to patients afflicted by sporadic gastric cancer, patients with HDGC receive, in large, identical systemic regimens. The lack of a robust preclinical in vitro system suitable for effective drug screening has been one of the obstacles to date which has hampered therapeutic advances in this rare disease.

METHODS

In order to identify therapeutic leads selective for the HDGC subtype of gastric cancer, we compared gene expression profiles and drug phenotype derived from an oncology library of 1912 compounds between gastric cancer cells established from a patient with metastatic HDGC harboring a c.1380delA CDH1 germline variant and sporadic gastric cancer cells.

RESULTS

Unsupervised hierarchical cluster analysis shows select gene expression alterations in c.1380delA CDH1 SB.mhdgc-1 cells compared to a panel of sporadic gastric cancer cell lines with enrichment of ERK1-ERK2 (extracellular signal regulated kinase) and IP3 (inositol trisphosphate)/DAG (diacylglycerol) signaling as the top networks in c.1380delA SB.mhdgc-1 cells. Intracellular phosphatidylinositol intermediaries were increased upon direct measure in c.1380delA CDH1 SB.mhdgc-1 cells. Differential high-throughput drug screening of c.1380delA CDH1 SB.mhdgc-1 versus sporadic gastric cancer cells identified several compound classes with enriched activity in c.1380 CDH1 SB.mhdgc-1 cells including mTOR (Mammalian Target Of Rapamycin), MEK (Mitogen-Activated Protein Kinase), c-Src kinase, FAK (Focal Adhesion Kinase), PKC (Protein Kinase C), or TOPO2 (Topoisomerase II) inhibitors. Upon additional drug response testing, dual PI3K (Phosphatidylinositol 3-Kinase)/mTOR and topoisomerase 2A inhibitors displayed up to >100-fold increased activity in hereditary c.1380delA CDH1 gastric cancer cells inducing apoptosis most effectively in cells with deficient CDH1 function.

CONCLUSION

Integrated pharmacological and transcriptomic profiling of hereditary diffuse gastric cancer cells with a loss-of-function c.1380delA CDH1 mutation implies various pharmacological vulnerabilities selective to CDH1-deficient familial gastric cancer cells and suggests novel treatment leads for future preclinical and clinical treatment studies of familial gastric cancer.

Selective blockade of B7-H3 enhances antitumour immune activity by reducing immature myeloid cells in head and neck squamous cell carcinoma

Immature myeloid cells including myeloid-derived suppressor cells (MDSCs) and tumour-associated macrophages (TAMs) promote tumour growth and metastasis by facilitating tumour transformation and angiogenesis, as well as by suppressing antitumour effector immune responses. Therefore, strategies designed to reduce MDSCs and TAMs accumulation and their activities are potentially valuable therapeutic goals. In this study, we show that negative immune checkpoint molecule B7-H3 is significantly overexpressed in human head and neck squamous cell carcinoma (HNSCC) specimen as compared with normal oral mucosa. Using immunocompetent transgenic HNSCC models, we observed that targeting inhibition of B7-H3 reduced tumour size. Flow cytometry analysis revealed that targeting inhibition of B7-H3 increases antitumour immune response by decreasing immunosuppressive cells and promoting cytotoxic T cell activation in both tumour microenvironment and macroenvironment. Our study provides direct in vivo evidence for a rationale for B7-H3 blockade as a future therapeutic strategy to treat patients with HNSCC.

Abstract B36: Preclinical development of a multikinase targeting molecule with activity against the cancer stem cell phenotype in pancreatic adenocarcinoma

Background: Pancreatic cancer is highly resistant to existing chemotherapy regimens, with only a minority of patients exhibiting a response to standard therapy. One aspect of treatment resistance is based on the cancer stem cell (CSC) hypothesis, which holds that a small population of highly chemoresistant cells is responsible for initiating and sustaining tumor growth. Compounds with activity against this population are highly desired in the adjuvant setting, where failure to sterilize micrometastases not detected at time of operation results in recurrence in nearly all patients.

Methods: A high-throughput drug screen (HTS) was performed in an in vitro model of pancreatic cancer stem-like cells (spheroids). Molecules with high potency against both the cancer stem cell-like spheroid and monolayer cell formats were evaluated for efficacy and mechanism of action in a variety of preclinical models of pancreatic cancer. Unbiased global in situ phosphoproteomic profiling using KiNativ technology was used to identify kinase targets impacted by the top hit. Stemness phenotype was interrogated by qRT-PCR of stemness genes, flow cytometry, colony formation assays, and tumor initiation in immunocompromised mice.

Results: The top hit from the HTS was a 1H-benzo[d]imidazol-2-amine-based inhibitor of interleukin-2-inducible T-cell kinase (ITK) (NCGC00188382, 1). 1 effectively mediated growth inhibition, blocked migration and invasion, and reduced clonogenicity of cancer cells with an associated decrease in the expression of several CSC-associated stemness markers at non-lethal concentrations (Sox2, Notch1) compared to gemcitabine used at >10-fold concentration. Metastatic burden in both the liver and lung was significantly reduced in mice orthotopically injected with pancreatic CSCs in the treatment group after 6 weeks.

Target deconvolution of 1 demonstrated inhibition of multiple select kinase targets. There were 16 targets identified from an initial screening panel of >400 kinases. The targets were further evaluated for the ability to phenocopy the effect of treatment with 1 via shRNA knockdown. Inhibition of the thousand-and-one amino acid kinase 3 (TAOK3), cyclin-dependent kinase 7 (CDK7), aurora B kinase (AURKB), and ephrin B2 receptor (EPHB2) effectively phenocopied the effect of treatment with 1. Concurrent silencing of two or more targets increased apoptosis induced by 1, suggesting intrinsic additivity of the multikinase agent. Enforced overexpression of TAOK3 increased expression of stemness markers, clonogenicity, and tumor initiation in vivo.

Conclusion: A potent inhibitor of ITK with a unique target profile and anti-stemness activities was derived from a differential HTS in a pancreatic spheroid CSC model. The 1H-benzo[d]imidazol-2-amine-derivative targets select characteristics attributed to pancreatic CSCs, including cell migration, colony formation, and metastasis formation with concomitant suppression of stemness traits without inducing cell death at the concentrations used. Target deconvolution of the compound identified multiple kinase targets, including TAOK3, a kinase not previously known to be involved in pancreatic tumor biology. Overexpression of TAOK3 results in an enforced CSC phenotype including increased colony formation and tumor initiation in vivo. The observed inhibitory effect of 1 on stemness phenotype at nanomolar concentrations without affecting cell viability or showing toxicity in vivo supports further preclinical development.

Citation Format: Taylor Aiken, Yansong Bian, Yaroslav Teper, Lesley Mathews Griner, Rajarshi Guha, Paul Shinn, Hong-Wu Xin, Holger Pflicke, Jian-kang Jiang, Paresma Patel, Steven Rogers, Jeffery Aube, Marc Ferrer, Craig J. Thomas, Udo Rudloff.{Authors}. Preclinical development of a multikinase targeting molecule with activity against the cancer stem cell phenotype in pancreatic adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B36.

TNF-α modulates genome-wide redistribution of ΔNp63α/TAp73 and NF-κB cREL interactive binding on TP53 and AP-1 motifs to promote an oncogenic gene program in squamous cancer

The Cancer Genome Atlas (TCGA) network study of 12 cancer types (PanCancer 12) revealed frequent mutation of TP53, and amplification and expression of related TP63 isoform ΔNp63 in squamous cancers. Further, aberrant expression of inflammatory genes and TP53/p63/p73 targets were detected in the PanCancer 12 project, reminiscent of gene programs comodulated by cREL/ΔNp63/TAp73 transcription factors we uncovered in head and neck squamous cell carcinomas (HNSCCs). However, how inflammatory gene signatures and cREL/p63/p73 targets are comodulated genome wide is unclear. Here, we examined how the inflammatory factor tumor necrosis factor-α (TNF-α) broadly modulates redistribution of cREL with ΔNp63α/TAp73 complexes and signatures genome wide in the HNSCC model UM-SCC46 using chromatin immunoprecipitation sequencing (ChIP-seq). TNF-α enhanced genome-wide co-occupancy of cREL with ΔNp63α on TP53/p63 sites, while unexpectedly promoting redistribution of TAp73 from TP53 to activator protein-1 (AP-1) sites. cREL, ΔNp63α and TAp73 binding and oligomerization on NF-κB-, TP53- or AP-1-specific sequences were independently validated by ChIP-qPCR (quantitative PCR), oligonucleotide-binding assays and analytical ultracentrifugation. Function of the binding activity was confirmed using TP53-, AP-1- and NF-κB-specific REs or p21, SERPINE1 and IL-6 promoter luciferase reporter activities. Concurrently, TNF-α regulated a broad gene network with cobinding activities for cREL, ΔNp63α and TAp73 observed upon array profiling and reverse transcription-PCR. Overlapping target gene signatures were observed in squamous cancer subsets and in inflamed skin of transgenic mice overexpressing ΔNp63α. Furthermore, multiple target genes identified in this study were linked to TP63 and TP73 activity and increased gene expression in large squamous cancer samples from PanCancer 12 TCGA by CircleMap. PARADIGM inferred pathway analysis revealed the network connection of TP63 and NF-κB complexes through an AP-1 hub, further supporting our findings. Thus, inflammatory cytokine TNF-α mediates genome-wide redistribution of the cREL/p63/p73, and AP-1 interactome, to diminish TAp73 tumor suppressor function and reciprocally activate NF-κB and AP-1 gene programs implicated in malignancy.

Myostatin in black Muscovy duck (Cairina moschata): full-length cDNA cloning and age-dependent mRNA expression compared with IGF-I

Insulin-like growth factor-I (IGF-I) and myostatin (MSTN) are a pair of critical positive and negative growth regulators. The aim of the current study was to examine the age-dependent and muscle-specific expression of IGF-I and MSTN mRNAs in black Muscovy ducks in order to understand their roles in regulating the postnatal muscle growth of domestic ducks. The full-length cDNA of the black Muscovy duck MSTN gene was cloned and the age-dependent mRNA expression profile was compared with that of the IGF-I mRNA in skeletal muscles. The cDNA sequence of the MSTN gene was 1128 bp in length and encodes 375 amino acids, with more than 94.9% homology with poultry MSTN genes, and 83.0-92.0% homology with that of human and mammals (accession: KR006339.1). The IGF-I and MSTN mRNA expression exhibited opposite trends in age-dependency and in different muscles: IGF-I mRNA level was high in the early postnatal stage and low in the late mature stage, corresponding positively to growth; while the MSTN mRNA was low in the early stage, increased gradually and reached the highest level in mature muscles, and was negatively related to muscle growth. In the breast muscles, IGF-I mRNA was much higher than in the leg muscles; the opposite effect was seen in MSTN mRNA. These data suggest that the relative expression levels of IGF-I and MSTN are essential determinants in the temporal and muscle-specific regulation of postnatal skeletal muscle growth in Muscovy duck and possibly in other poultry species as well.

MEK inhibitor PD-0325901 overcomes resistance to CK2 inhibitor CX-4945 and exhibits anti-tumor activity in head and neck cancer

The serine-threonine kinase CK2 exhibits genomic alterations and aberrant overexpression in human head and neck squamous cell carcinomas (HNSCC). Here, we investigated the effects of CK2 inhibitor CX-4945 in human HNSCC cell lines and xenograft models. The IC_50's of CX-4945 for 9 UM-SCC cell lines measured by MTT assay ranged from 3.4-11.9 μM. CX-4945 induced cell cycle arrest and cell death measured by DNA flow cytometry, and inhibited prosurvival mediators phospho-AKT and p-S6 in UM-SCC1 and UM-SCC46 cells. CX-4945 decreased NF-κB and Bcl-XL reporter gene activities in both cell lines, but upregulated proapoptotic TP53 and p21 reporter activities, and induced phospho-ERK, AP-1, and IL-8 activity in UM-SCC1 cells. CX-4945 exhibited modest anti-tumor activity in UM-SCC1 xenografts. Tumor immunostaining revealed significant inhibition of PI3K-Akt-mTOR pathway and increased apoptosis marker TUNEL, but also induced p-ERK, c-JUN, JUNB, FOSL1 and proliferation (Ki67) markers, as a possible resistance mechanism. To overcome the drug resistance, we tested MEK inhibitor PD-0325901 (PD-901), which inhibited ERK-AP-1 activation alone and in combination with CX-4945. PD-901 alone displayed significant anti-tumor effects in vivo, and the combination of PD-901 and CX-4945 slightly enhanced anti-tumor activity when compared with PD-901 alone. Immunostaining of tumor specimens after treatment revealed inhibition of p-AKT S129 and p-AKT T308 by CX-4945, and inhibition of p-ERK T202/204 and AP-1 family member FOSL-1 by PD-901. Our study reveals a drug resistance mechanism mediated by the MEK-ERK-AP-1 pathway in HNSCC. MEK inhibitor PD-0325901 is active in HNSCC resistant to CX-4945, meriting further clinical investigation.

TNF-αG-308A polymorphism is associated with insulin resistance: a meta-analysis

Tumor necrosis factor-α (TNF-α) promoter polymorphisms has been reported to be associated with obesity and insulin resistance and gained widespread attention. However, results obtained so far are quite conf‍‍licting. We therefore performed a meta-analysis to address this issue, basing on 17 studies from electronic databases (MEDLINE and EMBASE). No evidence of significant effect of TNF-αG-308A polymorphism on body mass index (BMI) or obesity risk was detected (BMI: WMDRE = 0.05, 95%CI: -0.62 to 0.73; risk of obesity: ORFE = 1.09, 95%CI: 0.87 to 1.35). G-308A variant was significantly associated with increased insulin levels in the overall (SMDFE = 0.12, 95%CI: 0.03 to 0.20) and obese subgroup analysis (SMDFE = 0.16, 95%CI: 0.03 to 0.29). In total, no significant result was observed for the association between TNF-α G-308A variant and HOMA-IR index. Nevertheless, subgroup analysis showed G-308A polymorphism was significantly associated with increased HOMA-IR in Caucasians (WMDFE = 0.49, 95%CI: 0.03 to 0.94). Our results indicate that TNF-αG-308A polymorphism has a significant effect on insulin resistance. However, it is unlikely that G-308A variant contributes to obesity.

Joint-multiple family linkage analysis predicts within-family variation better than single-family analysis of the maize nested association mapping population

Quantitative trait locus (QTL) mapping has been used to dissect the genetic architecture of complex traits and predict phenotypes for marker-assisted selection. Many QTL mapping studies in plants have been limited to one biparental family population. Joint analysis of multiple biparental families offers an alternative approach to QTL mapping with a wider scope of inference. Joint-multiple population analysis should have higher power to detect QTL shared among multiple families, but may have lower power to detect rare QTL. We compared prediction ability of single-family and joint-family QTL analysis methods with fivefold cross-validation for 6 diverse traits using the maize nested association mapping population, which comprises 25 biparental recombinant inbred families. Joint-family QTL analysis had higher mean prediction abilities than single-family QTL analysis for all traits at most significance thresholds, and was always better at more stringent significance thresholds. Most robust QTL (detected in >50% of data samples) were restricted to one family and were often not detected at high frequency by joint-family analysis, implying substantial genetic heterogeneity among families for complex traits in maize. The superior predictive ability of joint-family QTL models despite important genetic differences among families suggests that joint-family models capture sufficient smaller effect QTL that are shared across families to compensate for missing some rare large-effect QTL.

Abstract 2687: CK2 inhibitor CX-4945 modulates AKT, NF-kB, TP53 and MEK inhibitor PD-325901 targets AP1 mediated CK2 inhibitor drug resistance in head and neck cancer

We previously identified upregulated kinase CK2 as an activator of NF-B and repressor of TP53 in promoting the malignant phenotype of head and neck squamous cell carcinoma (HNSCC). Here, we investigate the anti-tumor effects of a small molecule CK2 inhibitor CX-4945, alone and in combination with MEK inhibitor PD-0325901 (PD-901), in human HNSCC models in vitro and in vivo. CX-4945 IC50s ranged from 3.4 µM to 11.9 µM in 9 UMSCC cell lines. CX-4945 caused S and G2/M cell cycle arrest, and induced sub-G0 DNA fragments, indicating cell death. CX-4945 inhibited NF-B and BcL-XL prosurvival reporter genes in wild type (wt) TP53 (UMSCC1) and mutant (mt) TP53 (UMSCC46) cell lines, and concurrently upregulated proapoptotic TP53, p21 and prosurvival AP-1 activity only in the wtTP53 cell line. Correspondingly, CK2 phosphorylation of AKT S129 as well as T308 and S473 prosurvival signaling was reduced in both cell lines, but AP-1 inducing p-Erk1/2Thr202/204 was increased in the wtTP53 cell line. In the UMSCC1 xenografts, CX-4945 treatment significantly decreased PI3K/Akt/mTOR pathway signaling by immunostaining. While CX-4945 increased TP53 and TUNEL apoptosis marker staining at early time points (13 days after CX4945 treatment), an opposing increase in p-Erk, FosL1, cJun, JunB, and proliferation (Ki67) were also observed. Consistent with these opposing effects, no significant tumor reduction or improvement in survival was observed by CX-4945 alone. However, combination of CX-4945 with MEK/ERK inhibitor PD-901 exhibited significant synergistic anti-proliferative effects in vitro. Significant anti-tumor effects were observed with MEK inhibitor alone and in combination with CX-4945 in vivo, further supporting a role for MEK/ERK/AP-1 in resistance to CX-4945 in this HNSCC model.

Supported by NIH Medical Research Scholars Program and NIDCD intramural projects ZIA-DC-000016, 73 and 74.

Citation Format: Yansong Bian, Jiawei Han, Vishnu Kannabiran, Suresh Mohan, Jay Friedman, Kenna Anderes, Zhong Chen, Carter Van Waes. CK2 inhibitor CX-4945 modulates AKT, NF-kB, TP53 and MEK inhibitor PD-325901 targets AP1 mediated CK2 inhibitor drug resistance in head and neck cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2687. doi:10.1158/1538-7445.AM2014-2687

CK2 phosphorylates and inhibits TAp73 tumor suppressor function to promote expression of cancer stem cell genes and phenotype in head and neck cancer

Cancer stem cells (CSC) and genes have been linked to cancer development and therapeutic resistance, but the signaling mechanisms regulating CSC genes and phenotype are incompletely understood. CK2 has emerged as a key signal serine/threonine kinase that modulates diverse signal cascades regulating cell fate and growth. We previously showed that CK2 is often aberrantly expressed and activated in head and neck squamous cell carcinomas (HNSCC), concomitantly with mutant (mt) tumor suppressor TP53, and inactivation of its family member, TAp73. Unexpectedly, we observed that classical stem cell genes Nanog, Sox2, and Oct4, are overexpressed in HNSCC with inactivated TAp73 and mtTP53. However, the potential relationship between CK2, TAp73 inactivation, and CSC phenotype is unknown. We reveal that inhibition of CK2 by pharmacologic inhibitors or siRNA inhibits the expression of CSC genes and side population (SP), while enhancing TAp73 mRNA and protein expression. Conversely, CK2 inhibitor attenuation of CSC protein expression and the SP by was abrogated by TAp73 siRNA. Bioinformatic analysis uncovered a single predicted CK2 threonine phosphorylation site (T27) within the N-terminal transactivation domain of TAp73. Nuclear CK2 and TAp73 interaction, confirmed by co-immunoprecipitation, was attenuated by CK2 inhibitor, or a T27A point-mutation of this predicted CK2 threonine phospho-acceptor site of TAp73. Further, T27A mutation attenuated phosphorylation, while enhancing TAp73 function in repressing CSC gene expression and SP cells. A new CK2 inhibitor, CX-4945, inhibited CSC related SP cells, clonogenic survival, and spheroid formation. Our study unveils a novel regulatory mechanism whereby aberrant CK2 signaling inhibits TAp73 to promote the expression of CSC genes and phenotype.

Inhibition of mTOR reduces anal carcinogenesis in transgenic mouse model

The molecular mechanism of human anal squamous cell carcinoma (ASCC) is unclear, and the accumulating evidence indicate association of ASCC with the activation of the Akt/mTOR pathway. Here we describe a mouse model with spontaneous anal squamous cell cancer, wherein a combined deletion of Tgfbr1 and Pten in stratified squamous epithelia was induced using inducible K14-Cre. Histopathologic analyses confirmed that 33.3% of the mice showed increased susceptibility to ASCC and precancerous lesions. Biomarker analyses demonstrated that the activation of the Akt pathway in ASCC of the Tgfbr1 and Pten double knockout (2cKO) mouse was similar to that observed in human anal cancer. Chemopreventive experiments using mTOR inhibitor-rapamycin treatment significantly delayed the onset of the ASCC tumors and reduced the tumor burden in 2cKO mice by decreasing the phosphorylation of Akt and S6. This is the first conditional knockout mouse model used for investigating the contributions of viral and cellular factors in anal carcinogenesis without carcinogen-mediated induction, and it would provide a platform for assessing new therapeutic modalities for treating and/or preventing this type of cancer.

Research potential of multi-lineage chicken amniotic mesenchymal stem cells

Amniotic mesenchymal stem cells (AMSCs) express octamer binding transcription factor 4 (Oct-4), which is necessary for maintaining the undifferentiated state of pluripotent stem cells. AMSCs also express CD29, CD44 and vimentin, which are specific markers of mesenchymal cells. We studied the biological characteristics and potential for cell therapy of AMSCs derived from 8-day-old chicken embryos. We induced the AMSCs to differentiate into adipocytes, osteoblasts and myocardial cells and used immunofluorescence, reverse transcription-polymerase chain reaction (RT-PCR) assays to detect the expressions of specific markers of AMSCs and differentiated cells. To assess the differentiation capacity of AMSCs, passage four cells were induced to differentiate into adipocytes, osteoblasts and myocardial cells. These results suggested that AMSCs isolated from chicken embryos exhibited the characteristics of multipotent stem cells. AMSCs, therefore, may be potential candidates for cellular transplantation therapy and tissue engineering.

PI3K/mTOR inhibitor PF-04691502 antitumor activity is enhanced with induction of wild-type TP53 in human xenograft and murine knockout models of head and neck cancer

PURPOSE

Phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway activation is often associated with altered expression or mutations of PIK3CA, TP53/p73, PTEN, and TGF-β receptors (TGFBR) in head and neck squamous cell carcinomas (HNSCC). However, little is known about how these alterations affect response to PI3K/mTOR-targeted agents.

EXPERIMENTAL DESIGN

In this preclinical study, PI3K/Akt/mTOR signaling was characterized in nine HNSCC (UM-SCC) cell lines and human oral keratinocytes. We investigated the molecular and anticancer effects of dual PI3K/mTOR inhibitor PF-04691502(PF-502) in UM-SCC expressing PIK3CA with decreased wild-type TP53, mutant TP53-/+ mutantTGFBR2, and in HNSCC of a conditional Pten/Tgfbr1 double knockout mouse model displaying PI3K/Akt/mTOR activation.

RESULTS

UM-SCC showed increased PIK3CA expression and Akt/mTOR activation, and PF-502 inhibited PI3K/mTORC1/2 targets. In human HNSCC expressing PIK3CA and decreased wtTP53 and p73, PF-502 reciprocally enhanced TP53/p73 expression and growth inhibition, which was partially reversible by p53 inhibitor pifithrin-α. Most UM-SCC with wtTP53 exhibited a lower IC50 than those with mtTP53 status. PF-502 blocked growth in G0-G1 and increased apoptotic sub-G0 DNA. PF-502 suppressed tumorigenesis and showed combinatorial activity with radiation in a wild-type TP53 UM-SCC xenograft model. PF-502 also significantly delayed HNSCC tumorigenesis and prolonged survival of Pten/Tgfbr1-deficient mice. Significant inhibition of p-Akt, p-4EBP1, p-S6, and Ki67, as well as increased p53 and TUNEL were observed in tumor specimens.

CONCLUSIONS

PI3K-mTOR inhibition can enhance TP53/p73 expression and significantly inhibit tumor growth alone or when combined with radiation in HNSCC with wild-type TP53. PIK3CA, TP53/p73, PTEN, and TGF-β alterations are potential modifiers of response and merit investigation in future clinical trials with PI3K-mTOR inhibitors.

Abstract LB-314: Preclinical investigation of antitumor effects of dual PI3K/mTOR inhibitor PF-04691502 in human xenograft and murine Pten/Tgfbr1 deficient head and neck cancer models

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and has a 5-year survival rate of ~50%. Therapy for HNSCC has only improved marginally over the past four decades, due in part to treatment resistance because of tumor heterogeneity. As such, effort is being directed toward personalizing treatment regimens for individual HNSCC patients using tumor genotyping and targeted small molecule inhibitors of the most activated and deleterious tumor pathways. The PI3K-Akt-mTOR axis is one of the most frequently altered signaling cascades in HNSCC, with amplifications or mutations in >90% of HNSCC tumors, and plays an important role in its pathogenesis. Recent evidence also implicates TP53 underexpression or mutation in over 80% of HNSCC tumor samples. As such, PI3K/mTOR and TP53 pathways are important in HNSCC development and could serve as useful therapeutic targets. In this study, we investigate the in vitro and in vivo effects of a novel dual molecular antagonist of PI3K/mTOR, PF-04691502 (PF-502), on PI3K/mTOR targets, TP53 activity, and HNSCC tumorigenesis. A panel of HNSCC (UM-SCC) cell lines was surveyed, the majority of which exhibited elevated expression of PI3K/mTOR pathway proteins when compared to normal human oral keratinocytes. These proteins include PI3K p110α, pAKT(S473), pAKT(T308), pmTOR, p4EBP1(S65, T37/46), and pS6(S240/244). PF-502 inhibits phosphorylation of these PI3K/mTOR targets and induces TP53 and p73 expression in UM-SCC cell lines. PI3K/mTOR target inhibition and TP53/p73 induction is associated with decreased cellular proliferation by MTT assay and increased apoptosis by flow cytometry. TP53 inhibition by pifithrin-α or siRNA knockdown partially attenuates the effects of PF-502, supporting a role of TP53 in growth inhibition. The effects of PF-502 on tumorigenicity were examined in human HNSCC xenografts in SCID mice and in conditional double Pten/Tgfbr1 knockout mice (2cKO), which develop HNSCC spontaneously. PF-502 inhibited or prevented tumor growth and prolonged host survival. PF-502 decreased pAKT(S473), p4EBP1(T37/46), pS6(S240/244) and proliferation marker, Ki67, as well as increased expression of TP53, p73, and TUNEL staining for apoptosis in tumor specimens by immunohistochemistry. Thus, PF-502 improves survival and inhibits the development and progression of HNSCC in preclinical models. Inhibition of pAkt, p4EBP1, pS6, and induction of TP53 and p73 are linked with the antitumor effects of PF-502 in HNSCC in vitro and in vivo, warranting further investigation of PI3K/mTOR inhibitors in a clinical subset of HNSCC patients with overactivation of PI3K/mTOR pathway and repression of TP53. Supported by NIH Medical Research Scholars Program (RVB), NIDCD intramural project ZIA-DC-000073, 74 (CVW) and NIDCR intramural project ZIA-DE-000698 (ABK).

Citation Format: Robert Vander Broek, Yansong Bian, Amanda Herzog, Bradford Hall, Jamie Coupar, Zhong Chen, Ashok B. Kulkarni, Carter Van Waes. Preclinical investigation of antitumor effects of dual PI3K/mTOR inhibitor PF-04691502 in human xenograft and murine Pten/Tgfbr1 deficient head and neck cancer models. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-314. doi:10.1158/1538-7445.AM2013-LB-314

TGF-β and NF-κB signal pathway cross-talk is mediated through TAK1 and SMAD7 in a subset of head and neck cancers

Transforming growth factor-beta (TGF-β) has a dual role in epithelial malignancies, including head and neck squamous cell carcinoma (HNSCC). Attenuation of canonical TGF-β signaling enhances de novo tumor development, whereas TGF-β overexpression and signaling paradoxically promotes malignant progression. We recently observed that TGF-β-induced growth arrest response is attenuated, in association with aberrant activation of nuclear factor-κB (NF-κB), a transcription factor, which promotes malignant progression in HNSCC. However, what role cross-talk between components of the TGF-β and NF-κB pathways plays in altered activation of these pathways has not been established. Here, we show TGF-β receptor II and TGF-β-activated kinase 1 (TAK1) are predominantly expressed in a subset of HNSCC tumors with nuclear activation of NF-κB family member RELA (p65). Further, TGF-β1 treatment induced sequential phosphorylation of TAK1, IKK, IκBα and RELA in human HNSCC lines. TAK1 enhances TGF-β-induced NF-κB activation, as TAK1 siRNA knockdown decreased TGF-β1-induced phosphorylation of IKK, IκB and RELA, degradation of IκBα, RELA nuclear translocation and DNA binding, and NF-κB-induced reporter and target gene transcription. Functionally, TAK1 siRNA inhibited cell proliferation, migration and invasion. Celastrol, a TAK1 inhibitor and anti-inflammatory compound used in traditional Chinese medicine, also decreased TGF-β1-induced phosphorylation of TAK1 and RELA, and suppressed basal, TGF-β1- and tumor necrosis factor-alpha (TNF-α)-induced NF-κB reporter gene activity. Celastrol also inhibited cell proliferation, while increasing sub-G0 DNA fragmentation and Annexin V markers of apoptosis. Furthermore, TGF-β and RELA activation promoted SMAD7 expression. In turn, SMAD7 preferentially suppressed TGF-β-induced SMAD and NF-κB reporters when compared with constitutive or TNF-α-induced NF-κB reporter gene activation. Thus, cross-talk by TGF-β via TAK1 and NF-κB promotes the malignant phenotype of HNSCC. Moreover, NF-κB may contribute to the downstream attenuation of canonical TGF-β signaling through increased SMAD7 expression. Celastrol highlights the therapeutic potential of agents targeting TAK1 as a key node in this pro-oncogenic TGF-β-NF-κB signal pathway.

Downregulation of endogenous intermedin augmented myocardial injury in rats with ischemia/reperfusion

Intermedin (IMD) plays an important regulatory role in cardiovascular function. We aimed to explore the protein expression of IMD and its receptors, calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs), and the role of endogenous IMD in myocardial ischemia/reperfusion (I/R) injury in rats. The rat model of I/R was created by ligating cardiac left anterior descending artery. Western blot was used to determine protein expression of CRLR and RAMPs, and radioimmunoassay was used to detect IMD content. Compared with control, protein levels of CRLR and RAMPs in both ischemic and nonischemic region were upregulated at different stages of reperfusion. IMD protein content in nonischemic area myocardium also increased. However, IMD protein content in ischemic area downregulated at 3-, 6-, and 12-h reperfusion. In hypoxia/reoxygenation model of neonatal cardiomyocytes, IMD attenuated myocyte injury, and IMD receptor antagonist IMD17-47 aggravated myocyte impairment by blocking endogenous IMD. In conclusion, the downregulation of IMD at early stage of reperfusion might augment myocardium injury.

Targeting of interleukin-13 receptor α2 for treatment of head and neck squamous cell carcinoma induced by conditional deletion of TGF-β and PTEN signaling

Background

The sixth leading class of cancer worldwide is head and neck cancer, which typically arise within the squamous epithelium of the oral mucosa. Human head and neck squamous cell carcinoma (HNSCC) is known to be difficult to treat and has only a 50% five-year survival rate. With HNSCC, novel therapeutics are needed along with a means of rapidly screening anti-cancer agents in vivo, such as mouse models.

Methods

In order to develop new animal models of cancer to test safety and efficacy of novel therapeutic agents for human HNSCC, tumors resembling clinical cases of human HNSCC were induced in the head and neck epithelium of a genetically engineered mouse model. This mouse model was generated by conditional deletion of two tumor suppressors, Transforming Growth Factor-β Receptor 1 (TGFβRI) and Phosphatase and Tensin homolog (PTEN), in the oral epithelium. We discovered that the tumors derived from these Tgfbr1/Pten double conditional knockout (2cKO) mice over-expressed IL-13Rα2, a high affinity receptor for IL-13 that can function as a tumor antigen. To demonstrate a proof-of-concept that targeted therapy against IL-13Rα2 expression would have any antitumor efficacy in this spontaneous tumor model, these mice were treated systemically with IL-13-PE, a recombinant immunotoxin consisting of IL-13 fused to the Pseudomonas exotoxin A.

Results

Tgfbr1/Pten 2cKO mice when treated with IL-13-PE displayed significantly increased survival when compared to the untreated control mice. The untreated mice exhibited weight loss, particularly with the rapid onset of tongue tumors, but the treated mice gained weight while on IL-13-PE therapy and showed no clinical signs of toxicity due to the immunotoxin. Expression of IL-13Rα2 in tumors was significantly decreased with IL-13-PE treatment as compared to the controls and the number of myeloid-derived suppressor cells (MDSC) was also significantly reduced in the spleens of the IL-13-PE treated mice.

Conclusions

Our study demonstrates that the Tgfbr1/Pten 2cKO mouse model of human HNSCC is a useful model for assessing antitumor activity of new cancer therapeutic agents, and that IL-13-PE has therapeutic potential to treat human head and neck cancer.

MicroRNA-135b acts as a tumor promoter by targeting the hypoxia-inducible factor pathway in genetically defined mouse model of head and neck squamous cell carcinoma

Here in, we investigated the mechanism underlying overexpression of miR-135b in the human head and neck squamous cell carcinoma (HNSCC) cell lines and in the HNSCC mouse model. Exogenous expression of miR-135b in these cell lines increased cell proliferation, migration, and colony formation. Gene silencing analysis revealed that miR-135b affects a regulator that inhibits hypoxia-inducible factor (HIF). Increased miR-135b expression was positively correlated with HIF-1α expression and microvessel density in the HNSCC model. Thus, our data demonstrate that miR-135b acts as a tumor promoter by promoting cancer cell proliferation, colony formation, survival, and angiogenesis through activation of HIF-1α in HNSCC.