Alcohol consumption, multiple Lugol-voiding lesions, and field cancerization

The development of multiple squamous cell carcinomas (SCC) in the upper aerodigestive tract, which includes the oral cavity, pharynx, larynx, and esophagus, is explained by field cancerization and is associated with alcohol consumption and cigarette smoking. We reviewed the association between alcohol consumption, multiple Lugol-voiding lesions, and field cancerization, mainly based on the Japan Esophageal Cohort study. The Japan Esophageal Cohort study is a prospective cohort study that enrolled patients with esophageal SCC after endoscopic resection. Enrolled patients received surveillance by gastrointestinal endoscopy every 6 months and surveillance by an otolaryngologist every 12 months. The Japan Esophageal Cohort study showed that esophageal SCC and head and neck SCC that developed after endoscopic resection for esophageal SCC were associated with genetic polymorphisms related to alcohol metabolism. They were also associated with Lugol-voiding lesions grade in the background esophageal mucosa, the score of the health risk appraisal model for predicting the risk of esophageal SCC, macrocytosis, and score on alcohol use disorders identification test. The standardized incidence ratio of head and neck SCC in patients with esophageal SCC after endoscopic resection was extremely high compared to the general population. Drinking and smoking cessation is strongly recommended to reduce the risk of metachronous esophageal SCC after treatment of esophageal SCC. Risk factors for field cancerization provide opportunities for early diagnosis and minimally invasive treatment. Lifestyle guidance of alcohol consumption and cigarette smoking for esophageal precancerous conditions, which are endoscopically visualized as multiple Lugol-voiding lesions, may play a pivotal role in decreasing the incidence and mortality of esophageal SCC.

ALDH2 dysfunction and alcohol cooperate in cancer stem cell enrichment

The alcohol metabolite acetaldehyde is a potent human carcinogen linked to esophageal squamous cell carcinoma (ESCC) initiation and development. Aldehyde dehydrogenase 2 (ALDH2) is the primary enzyme that detoxifies acetaldehyde in the mitochondria. Acetaldehyde accumulation causes genotoxic stress in cells expressing the dysfunctional ALDH2E487K dominant negative mutant protein linked to ALDH2*2, the single nucleotide polymorphism highly prevalent among East Asians. Heterozygous ALDH2*2 increases the risk for the development of ESCC and other alcohol-related cancers. Despite its prevalence and link to malignant transformation, how ALDH2 dysfunction influences ESCC pathobiology is incompletely understood. Herein, we characterize how ESCC and preneoplastic cells respond to alcohol exposure using cell lines, three-dimensional organoids and xenograft models. We find that alcohol exposure and ALDH2*2 cooperate to increase putative ESCC cancer stem cells with high CD44 expression (CD44H cells) linked to tumor initiation, repopulation and therapy resistance. Concurrently, ALHD2*2 augmented alcohol-induced reactive oxygen species and DNA damage to promote apoptosis in the non-CD44H cell population. Pharmacological activation of ALDH2 by Alda-1 inhibits this phenotype, suggesting that acetaldehyde is the primary driver of these changes. Additionally, we find that Aldh2 dysfunction affects the response to cisplatin, a chemotherapeutic commonly used for the treatment of ESCC. Aldh2 dysfunction facilitated enrichment of CD44H cells following cisplatin-induced oxidative stress and cell death in murine organoids, highlighting a potential mechanism driving cisplatin resistance. Together, these data provide evidence that ALDH2 dysfunction accelerates ESCC pathogenesis through enrichment of CD44H cells in response to genotoxic stressors such as environmental carcinogens and chemotherapeutic agents.

Combination therapy with WEE1 inhibition and trifluridine/tipiracil against esophageal squamous cell carcinoma

Despite advanced therapeutics, esophageal squamous cell carcinoma (ESCC) remains one of the deadliest cancers. Here, we propose a novel therapeutic strategy based on synthetic lethality combining trifluridine/tipiracil and MK1775 (WEE1 inhibitor) as a treatment for ESCC. This study demonstrates that trifluridine induces single-strand DNA damage in ESCC cells, as evidenced by phosphorylated replication protein 32. The DNA damage response includes cyclin-dependent kinase 1 (CDK1) (Tyr15) phosphorylation as CDK1 inhibition and a decrease of the proportion of phospho-histone H3 (p-hH3)-positive cells, indicating cell cycle arrest at the G2 phase before mitosis entry. The WEE1 inhibitor remarkedly suppressed CDK1 phosphorylation (Try15) and reactivated CDK1, and also increased the proportion of p-hH3-positive cells, which indicates an increase of the number of cells into mitosis. Trifluridine combined with a WEE1 inhibitor increased trifluridine-mediated DNA damage, namely DNA double-strand breaks, as shown by increased γ-H2AX expression. Moreover, the combination treatment with trifluridine/tipiracil and a WEE1 inhibitor significantly suppressed tumor growth of ESCC-derived xenograft models. Hence, our novel combination treatment with trifluridine/tipiracil and a WEE1 inhibitor is considered a candidate treatment strategy for ESCC.

Risk factors for the development of second primary esophageal squamous-cell carcinoma after endoscopic resection for esophageal squamous-cell carcinoma according to genetic polymorphisms related to alcohol and nicotine metabolism

BACKGROUND

Multiple development of esophageal squamous-cell carcinoma is explained by field cancerization and is associated with alcohol consumption and smoking. We investigated the association between the development of second primary esophageal squamous-cell carcinoma after endoscopic resection for esophageal squamous-cell carcinoma and genetic polymorphisms related to alcohol and nicotine metabolism.

METHODS

The study group comprised 56 patients with esophageal squamous-cell carcinoma after endoscopic resection. The main variables were the following: (i) cumulative incidence and total number of second primary esophageal squamous-cell carcinoma according to genetic polymorphisms in alcohol dehydrogenase 1B, aldehyde dehydrogenase 2 and cytochrome P450 2A6; and (ii) risk factors of second primary esophageal squamous-cell carcinoma identified using a multivariate Cox proportional-hazards model. The frequencies of alcohol dehydrogenase 1B, aldehyde dehydrogenase 2 and cytochrome P450 2A6 genetic polymorphisms in the buccal mucosa were analyzed.

RESULTS

The median follow-up was 92.8 months (range: 2.7-134.2). Slow-metabolizing alcohol dehydrogenase 1B was associated with a higher 7-year cumulative incidence of second primary esophageal squamous-cell carcinoma (fast-metabolizing alcohol dehydrogenase 1B vs slow-metabolizing alcohol dehydrogenase 1B: 20.5% vs 71.4%, P = 0.006). Slow-metabolizing alcohol dehydrogenase 1B (relative risk [95% confidence interval]: 3.17 [1.49-6.73]), inactive aldehyde dehydrogenase 2 (2.17 [1.01-4.63]) and poorly-metabolizing cytochrome P450 2A6 (4.63 [1.74-12.33]) had a significantly higher total number of second primary esophageal squamous-cell carcinoma per 100 person-years. In the multivariate Cox proportional-hazards model, slow-metabolizing alcohol dehydrogenase 1B was a significant risk factor of the development of second primary esophageal squamous-cell carcinoma (hazard ratio 9.92, 95% confidence interval: 2.35-41.98, P = 0.0018).

CONCLUSIONS

Slow-metabolizing alcohol dehydrogenase 1B may be a significant risk factor for the development of second primary esophageal squamous-cell carcinoma. In addition, inactive aldehyde dehydrogenase 2 and poorly-metabolizing cytochrome P450 2A6 may be important factors.

Abstract 6187: The combination of Trifluridine/Tipiracil and a WEE1 inhibitor is an effective and tolerable candidate strategy against ESCC

Background: Recently we reported that trifluridine (FTD)/Tipiracil (TPI) is tolerable for unresectable Esophageal squamous cell carcinoma (ESCC) patients although the anti-tumor effect was modest (Mori Y, et al. Esophagus 2022). Therefore, we aimed at developing a combination therapy with FTD/TPI with another small molecule to achieve better efficacy against ESCC. CHK1 inhibitor was considered to be the candidate, because combination treatment with FTD/TPI and prexasertib showed potent antitumor effects in p53-mutant ESCC cells through the synthetic lethality (Ohashi S, et al. Mol Cancer Ther 2020); however, CHK1 inhibitors are not clinically available for further clinical development. Here we explored the concept of synthetic lethality with CHK1 perturbation to the whole ATR-CHK1-WEE1 pathway, especially to the downward WEE1 which directly targets a cell cycle regulator CDK1. The aim of this study is to elucidate the efficacy of the combination of a WEE1 inhibitor (WEE1i) MK1775 with FTD/TPI in ESCC.

Methods: ESCC cells (TE-8 and TE-11) are used for in vitro assay, with compounds including FTD, MK1775 (WEE1i). Mitosis assay (flowcytometry with phospho-Histone H3 [p-hH3] antibody), cell viability assay (WST-1 and clonogenic assays), cytotoxicity assay (CytoTox-Glo assay), and western blotting (double-strand DNA break [γ-H2AX], DDR activity [phospho-CHK1], and CDK1 activity [phospho-Tyr15-CDK1]) were performed. Antitumor effects and tolerability were observed in vivo with TE-8 xenograft model with nu/nu nude mice.

Results: FTD induced activation of CHK1 and inhibition of CDK1 sequentially in ESCC cells. FTD also decreased the proportion of p-hH3 positive cells in mitosis assay. Combination treatment with WEE1i and FTD had activated CDK1, increased p-hH3 positive cells, and induced γ-H2AX. The WST-1 cell viability assay showed significant sensitizing effect of WEE1i to FTD in ESCC cells. The cytotoxicity assay also revealed the significant increase of dead cells by the combination treatment (p = 0.003). Furthermore, we confirmed the combination treatment significantly suppressed xenografted tumor growth (-86%) without major adverse events in vivo (two-way ANOVA and Tukey post-hoc analyses: FTD/TPI vs. control, P < 0.05; MK1775 vs. control, P < 0.05, without significant interaction between the FTD/TPI treatment and MK1775 treatment).

Conclusion: FTD/TPI and WEE1i combination showed potent cytotoxicity, and is considered as a candidate treatment strategy against ESCC.

Citation Format: Hoang Trang Nguyen Vu, Osamu Kikuchi, Tomoki Saito, Yukie Nakai, Tomomi Ida, Yuki Kondo, Shigeki Kataoka, Yosuke Mitani, Shinya Ohashi, Manabu Muto. The combination of Trifluridine/Tipiracil and a WEE1 inhibitor is an effective and tolerable candidate strategy against ESCC. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6187.

Clinicopathological and molecular characterization of deficient mismatch repair colorectal cancer

Tumors demonstrating deficient mismatch repair (dMMR) account for 12%-15% of colorectal cancers (CRCs), but their characteristics have not been fully elucidated. The aim of this study was to characterize dMMR CRCs in terms of clinicopathological findings and molecular alterations. Immunostaining for mismatch repair (MMR) proteins was performed to determine MMR status, and then MLH1 promoter methylation and genetic variants of 25 genes involved in colorectal carcinogenesis were analyzed by next-generation sequencing in dMMR tumors. Coexistence of precancerous lesions was histologically evaluated to characterize the type of precursors. Immunohistochemistry revealed 34 dMMR tumors in 492 CRCs. Among dMMR CRCs, there were 25 MLH1 methylation-positive, 16 BRAF V600E variant-positive, and 7 KRAS variant-positive tumors. Positive MLH1 methylation was associated with BRAF V600E, older age, and right-side tumor location. MLH1 methylated BRAF/KRAS wild-type tumors were distinct in that all 5 tumors possessed variants in ligand-independent WNT signaling genes including APC, AXIN2, and CTNNB1. Among 10 dMMR CRCs that presented with precancerous lesions, 4 BRAF variant-positive, 1 KRAS variant-positive, and 2 BRAF/KRAS wild-type MLH1 methylated tumors coexisted with serrated lesions, whereas 1 MLH1 methylated BRAF/KRAS wild-type tumor and 2 MLH1 unmethylated tumors accompanied conventional adenomas. The present study characterized distinct subgroups of dMMR CRCs based on molecular alterations including MLH1 methylation and variants in BRAF, KRAS, and ligand-independent WNT signaling genes. The existence of distinct precursor lesions including serrated lesion and conventional adenoma further illustrates the involvement of heterogeneous carcinogenetic pathways in the development of dMMR CRCs.

FGFR2 maintains cancer cell differentiation via AKT signaling in esophageal squamous cell carcinoma

Fibroblast growth factors (FGFs) and their receptors (FGFRs) are important for signaling to maintain cancer stem-like cells (CSCs) in esophageal squamous cell carcinoma (ESCC). However, which FGF receptor, 1, 2, 3, 4, and L1, is essential or whether FGFRs have distinct different roles in ESCC-CSCs is still in question. This study shows that FGFR2, particularly the IIIb isoform, is highly expressed in non-CSCs. Non-CSCs have an epithelial phenotype, and such cells are more differentiated in ESCC. Further, FGFR2 induces keratinocyte differentiation through AKT but not MAPK signaling and diminishes CSC populations. Conversely, knockdown of FGFR2 induces epithelial-mesenchymal transition (EMT) and enriches CSC populations in ESCC. Finally, data analysis using The Cancer Genome Atlas (TCGA) dataset shows that expression of FGFR2 significantly correlated with cancer cell differentiation in clinical ESCC samples. The present study shows that each FGFR has a distinct role and FGFR2-AKT signaling is a key driver of keratinocyte differentiation in ESCC. Activation of FGFR2-AKT signaling could be a future therapeutic option targeting CSC in ESCC.

Association of local complete response with prognosis after salvage photodynamic therapy for esophageal squamous cell carcinoma

OBJECTIVES

Photodynamic therapy (PDT) is an effective salvage endoscopic treatment for local failure at the primary site after chemoradiotherapy (CRT) in esophageal cancer patients. However, the contribution of local control by salvage PDT to the prognosis is unclear. We investigated whether complete response at primary site by salvage PDT could improve the prognosis.

METHODS

Between January 2008 and March 2016, 34 patients received salvage PDT for local failure of esophageal cancer limited to stage T1-2 after definitive CRT or radiotherapy. Local complete response (L-CR) rate, adverse events, overall survival (OS), and progression-free survival (PFS) were assessed retrospectively.

RESULTS

Local complete response rates after PDT were 68% (23/34; 95% CI, 50-83%) in all patients: 81% (17/21; 95% CI, 58-95%) for stage T1 and 46% (6/13; 95% CI, 19-75%) for stage T2 patients. Grade 3 esophageal stricture occurred in one patient. The median follow-up was 26.0 months (range, 3.7-93.6 months); 21 patients died. The median survival times were 54.3 months in patients who achieved L-CR after PDT (L-CR group) and 19.8 months in those who did not (non-CR group). The 2-year OS rates were 79% (95% CI, 54-92%) in the L-CR group and 40% (95% CI, 11-68%) in the non-CR group (P = 0.0389; log-rank test). The median PFS was 21.2 months in the L-CR group and 1.9 months in the non-CR group (P < 0.001; log-rank test).

CONCLUSION

Achieving L-CR by salvage PDT for local failure after CRT in esophageal cancer was associated with good prognosis.

Visceral fat obesity is the key risk factor for the development of reflux erosive esophagitis in 40-69-years subjects

BACKGROUND

Visceral fat obesity can be defined quantitatively by abdominal computed tomography, however, the usefulness of measuring visceral fat area to assess the etiology of gastrointestinal reflux disease has not been fully elucidated.

METHODS

A total of 433 healthy subjects aged 40-69 years (234 men, 199 women) were included in the study. The relationship between obesity-related factors (total fat area, visceral fat area, subcutaneous fat area, waist circumference, and body mass index) and the incidence of reflux erosive esophagitis was investigated. Lifestyle factors and stomach conditions relevant to the onset of erosive esophagitis were also analyzed.

RESULTS

The prevalence of reflux erosive esophagitis was 27.2% (118/433; 106 men, 12 women). Visceral fat area was higher in subjects with erosive esophagitis than in those without (116.6 cm² vs. 64.9 cm², respectively). The incidence of erosive esophagitis was higher in subjects with visceral fat obesity (visceral fat area ≥ 100 cm²) than in those without (61.2% vs. 12.8%, respectively). Visceral fat obesity had the highest odds ratio (OR) among obesity-related factors. Multivariate analysis showed that visceral fat area was associated with the incidence of erosive esophagitis (OR = 2.18), indicating that it is an independent risk factor for erosive esophagitis. In addition, daily alcohol intake (OR = 1.54), gastric atrophy open type (OR = 0.29), and never-smoking history (OR = 0.49) were also independently associated with the development of erosive esophagitis.

CONCLUSIONS

Visceral fat obesity is the key risk factor for the development of reflux erosive esophagitis in subjects aged 40-69 years.

Cancer of unknown primary with EGFR mutation successfully treated with targeted therapy directed by clinical next-generation sequencing: a case report

BACKGROUND

Cancer of unknown primary (CUP) is usually treated with nonselective and empirical chemotherapy; however, its prognosis is generally poor, with a median survival of less than a year. Thus, clinicians eagerly await the development of more effective treatment strategies. In recent years, advances in next-generation sequencing (NGS) have made it possible to analyze comprehensively the genome of individual cancers. NGS has identified many genomic alterations, some of which are potential molecular targets of specific agents. We report a case of CUP that was successfully treated with targeted therapy directed by the genomic data obtained from an NGS-based multiplex assay.

CASE PRESENTATION

A 52-year-old Asian woman with right hip joint pain underwent fluorodeoxyglucose-positron emission tomography/computed tomography, which showed multiple metastatic tumors in her right hip joint, thyroid gland, lung, and vertebrae. Brain magnetic resonance imaging showed multiple cerebral metastases. Additional tests, including pathology examination and conventional epidermal growth factor receptor (EGFR) gene mutation analysis (single-strand conformation polymorphism assay), could not identify the primary origin of the tumors, so the patient was diagnosed with CUP. After empirical chemotherapy for CUP, an NGS-based multiplex assay performed using a resected specimen of thyroid tumor detected the EGFR mutation c.2573 T > G p.Leu858Arg (L858R). Her treatment was changed to erlotinib, an EGFR tyrosine-kinase inhibiter, which dramatically shrank the tumors and decreased her serum carcinoembryonic antigen level. She achieved long-term disease control and survived for 2 years and 9 months from the first diagnosis.

CONCLUSION

This case might support the strategy that NGS-based multiplex assays could identify actionable molecular targets for individual patients with CUP.

Autophagy mitigates ethanol-induced mitochondrial dysfunction and oxidative stress in esophageal keratinocytes

During alcohol consumption, the esophageal mucosa is directly exposed to high concentrations of ethanol (EtOH). We therefore investigated the response of normal human esophageal epithelial cell lines EPC1, EPC2 and EPC3 to acute EtOH exposure. While these cells were able to tolerate 2% EtOH for 8 h in both three-dimensional organoids and monolayer culture conditions, RNA sequencing suggested that EtOH induced mitochondrial dysfunction. With EtOH treatment, EPC1 and EPC2 cells also demonstrated decreased mitochondrial ATPB protein expression by immunofluorescence and swollen mitochondria lacking intact cristae by transmission electron microscopy. Mitochondrial membrane potential (ΔΨm) was decreased in a subset of EPC1 and EPC2 cells stained with ΔΨm–sensitive dye MitoTracker Deep Red. In EPC2, EtOH decreased ATP level while impairing mitochondrial respiration and electron transportation chain functions, as determined by ATP fluorometric assay, respirometry, and liquid chromatography-mass spectrometry. Additionally, EPC2 cells demonstrated enhanced oxidative stress by flow cytometry for mitochondrial superoxide (MitoSOX), which was antagonized by the mitochondria-specific antioxidant MitoCP. Concurrently, EPC1 and EPC2 cells underwent autophagy following EtOH exposure, as evidenced by flow cytometry for Cyto-ID, which detects autophagic vesicles, and immunoblots demonstrating induction of the lipidated and cleaved form of LC3B and downregulation of SQSTM1/p62. In EPC1 and EPC2, pharmacological inhibition of autophagy flux by chloroquine increased mitochondrial oxidative stress while decreasing cell viability. In EPC2, autophagy induction was coupled with phosphorylation of AMP activated protein kinase (AMPK), a cellular energy sensor responding to low ATP levels, and dephosphorylation of downstream substrates of mechanistic Target of Rapamycin Complex (mTORC)-1 signaling. Pharmacological AMPK activation by AICAR decreased EtOH-induced reduction of ΔΨm and ATP in EPC2. Taken together, acute EtOH exposure leads to mitochondrial dysfunction and oxidative stress in esophageal keratinocytes, where the AMPK-mTORC1 axis may serve as a regulatory mechanism to activate autophagy to provide cytoprotection against EtOH-induced cell injury.

Protective effects of Alda-1, an ALDH2 activator, on alcohol-derived DNA damage in the esophagus of human ALDH2*2 (Glu504Lys) knock-in mice

Alcohol consumption is the key risk factor for the development of esophageal squamous cell carcinoma (ESCC), and acetaldehyde, a metabolite of alcohol, is an alcohol-derived major carcinogen that causes DNA damage. Aldehyde dehydrogenase2 (ALDH2) is an enzyme that detoxifies acetaldehyde, and its activity is reduced by ALDH2 gene polymorphism. Reduction in ALDH2 activity increases blood, salivary and breath acetaldehyde levels after alcohol intake, and it is deeply associated with the development of ESCC. Heavy alcohol consumption in individuals with ALDH2 gene polymorphism significantly elevates the risk of ESCC; however, effective prevention has not been established yet. In this study, we investigated the protective effects of Alda-1, a small molecule ALDH2 activator, on alcohol-mediated esophageal DNA damage. Here, we generated novel genetically engineered knock-in mice that express the human ALDH2*1 (wild-type allele) or ALDH2*2 gene (mutant allele). Those mice were crossed, and human ALDH2*1/*1, ALDH2*1/*2 and ALDH2*2/*2 knock-in mice were established. They were given 10% ethanol for 7 days in the presence or absence of Alda-1, and we measured the levels of esophageal DNA damage, represented by DNA adduct (N²-ethylidene-2′-deoxyguanosine). Alda-1 significantly increased hepatic ALDH2 activity both in human ALDH2*1/*2 and/or ALDH2*2/*2 knock-in mice and reduced esophageal DNA damage levels after alcohol drinking. Conversely, cyanamide, an ALDH2-inhibitor, significantly exacerbated esophageal DNA adduct level in C57BL/6N mice induced by alcohol drinking. These results indicate the protective effects of ALDH2 activation by Alda-1 on esophageal DNA damage levels in individuals with ALDH2 gene polymorphism, providing a new insight into acetaldehyde-mediated esophageal carcinogenesis and prevention.

Abstract 1670: Characterization of the chick chorioallantoic membrane tumor model in comparison with various xenograft mouse tumors

Background: The chick chorioallantoic membrane (CAM) tumor model is an in vivo three-dimensional culture model that is easy to use and inexpensive, has no ethical issues, and has been used in cancer research, although the success rate of generating CAM tumors varies among reports. We analyzed the success rate of CAM tumors from patient-derived xenograft (PDX) of esophageal squamous cell carcinoma (ESCC) and many cell line-derived xenograft (CDX) tumors of different cancer types, and we sought to determine which factors affected the success rate of generating CAM tumors.

Method: We used patient cancer tissue (ESCC) and/or commercially available 12 tumorigenic cancer cell lines (esophageal cancer [TE-11 and HCE4], pancreatic cancer [CFPA-1, MIA PaCa2, and PANC-1], lung cancer [A549 and H358], skin cancer [A431 and B16F10], and biliary tract cancer [HuCCT-1, TFK-1, and MzchA2]) to generate xenograft tumors. Small (1- to 2-mm) pieces of xenograft tumors were grafted onto the CAMs of fertilized eggs. After incubating for an additional 7 to 9 days at 37.5°C and 65% humidity, nodules were observed on the assigned locations of each CAM. On the basis of hematoxylin and eosin (H&E) staining, we calculated the success rate of the CAM tumor engraftment. H&E staining was also performed with parental PDX or CDX tumors as well as parental ESCC tissues, to compare them with CAM tumors.

Results: A total of 29 xenograft tumors were transplanted onto CAMs. The overall success rate in generating CAM tumors was 19/29 (66%). The CAM tumors were histologically quite similar to those of their parental CDX or PDX tumors, and the CAM tumors from PDX ESCC were also histologically similar to their parent ESCC tumors. Tumor pieces from poorly-differentiated xenograft tumors (including PDX ESCC) generated CAM tumors with a 90% success rate (19/21), in comparison with well-differentiated xenograft tumors, whose success rate was 0% (0/8).

Conclusion: The overall success rate in generating CAM tumors, especially from poorly differentiated tumors, seems acceptable. The histological similarity between CAM tumors and both parent xenograft and parent tumors from humans indicates that the CAM tumor model is a promising in vivo model for the study of poorly differentiated tumors. As for well-differentiated tumors, this model has to be further optimized to increase the success rate of engraftment.

Citation Format: Tomoki Saito, Shinya Ohashi, Ayaka Mizumoto, Osamu Kikuchi, Kotaro Matsumoto, Aoi Komatsu, Seiji Naganuma, Yoshihiro Yamamoto, Kenshiro Hirohashi, Masahiro Yoshioka, Masashi Tamaoki, Makiko Funakoshi, Fuyuhiko Tamanoi, Manabu Muto. Characterization of the chick chorioallantoic membrane tumor model in comparison with various xenograft mouse tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1670.

E487K-Induced Disorder in Functionally Relevant Dynamics of Mitochondrial Aldehyde Dehydrogenase 2

Mitochondrial aldehyde dehydrogenase 2 (ALDH2), which is a homotetramer assembled by two equivalent dimers, is an important enzyme that metabolizes ethanol-derived acetaldehyde to acetate in a coenzyme-dependent manner. The highly reactive acetaldehyde exhibits a toxic effect, indicating that the proper functioning of ALDH2 is essential to counteract aldehyde-associated diseases. It is known that the catalytic activity of ALDH2 is drastically impaired by a frequently observed mutation, E487K, in a dominant fashion. However, the molecular basis of the inactivation mechanism is elusive because of the complex nature of the dynamic behavior. Here, we performed microsecond-timescale molecular dynamics simulations of the proteins complexed with coenzymes. The E487K mutation elevated the conformational heterogeneity of the dimer interfaces, which are relatively distal from the substituted residue. Dynamic network analyses showed that Glu487 and the dimer interface were dynamically communicated, and the dynamic community further spanned throughout all of the subunits in the wild-type; however, this network was completely rearranged by the E487K mutation. The perturbation of the dynamic properties led to alterations of the global conformational motions and destabilization of the coenzyme binding required for receiving a proton from the catalytic nucleophile. The insights into the dynamic behavior of the dominant negative mutant in this work will provide clues to restore its function.

THU0568 EFFECTIVENESS OF FOOT ORTHOSIS TO PROMOTE PHYSICAL ACTIVITY FOR PATIENTS WITH CONCURRENT RHEUMATOID ARTHRITIS AND SARCOPENIA

Background:

Sarcopenia is a progressive systemic skeletal muscle disorder associated with an increased likelihood of adverse outcomes including physical disability, falls, and mortality. The muscle mass of patients with rheumatoid arthritis (RA) is lower than that of age-matched healthy individuals, and a high prevalence rate of sarcopenia has been reported1). In particular, foot deformities may increase the prevalence rate of sarcopenia because of inactivity due to foot pain on walking. Treatment with a foot orthosis (FO) can reportedly reduce pain2); however, whether a FO can resolve inactivity and sarcopenia is unclear.

Objectives:

To elucidate the effectiveness of a FO on physical activity and sarcopenia in patients with RA.

Methods:

Thirty patients with RA with foot deformities were enrolled from April 2017 to December 2019. Sarcopenia was diagnosed using the algorithm of the European Working Group on Sarcopenia in Older People, and the cut-off values of the Asian Working Group for Sarcopenia were applied. We also collected the clinical variables of patients with concurrent RA and sarcopenia who continued to use a FO for 6 months. The primary outcome was physical activity determined by the International Physical Activity Questionnaire. The secondary outcomes were foot pain measured with a visual analog scale; activities of daily living (ADL) measured with the Health Assessment Questionnaire; and body mass index, body fat percentage, and the skeletal muscle mass index measured with a body composition device. The clinical variables were compared between baseline and 6 months after continuous treatment with a FO.

Results:

The prevalence rate of sarcopenia was 76.6% (23/30), and nine patients with RA continued to use the FO for 6 months. Table 1 shows outcomes at baseline and after 6 months of treatment with a FO. The only clinical variable that showed a significant difference was foot pain. Physical activities, ADL, and body compositions were maintained after 6 months.

Table 1.

Outcomes of 6-month treatment with FO

Baseline6 monthsp valuePhysical activityIPAQWalking, MET-min/weekModerate, MET-min/weekVigorous, MET-min/week132 (66, 594)0 (0, 0)0 (0, 0)594 (396, 2376)0 (0, 0)0 (0, 0)0.071.000.32Foot painVAS score4.6 (3.1, 7.4)2.8 (1.1, 4.7)0.02ADLHAQ1.5 (1.1, 2.3)1.1 (0.9, 1.5)0.07Body compositionBMI, kg/m2BFP, %SMI, kg/m221.4 (20.7, 22.7)31.1 (24.2, 37.6)5.2 (4.8, 5.3)20.7 (19.3, 22.1)32.9 (26.3, 36.5)5.2 (5.0, 5.2)0.890.820.61

IPAQ: International Physical Activity Questionnaire, VAS: visual analog scale, ADL: activities of daily living, HAQ: Health Assessment Questionnaire, BMI: body mass index, BFP: body fat percentage, SMI: skeletal muscle mass index

Data are presented as median (lower quartile, upper quartile)

Conclusion:

The prevalence rate of sarcopenia in patients with RA with foot deformities was much higher than previous reported1). However, 6 months of treatment with a FO not only reduced foot pain but also maintained physical activity and muscle mass. Physical therapy has recently been recommended for patients with inflammatory arthritis. physical activity and muscle mass of patients with RA and concurrent foot deformities may be increased by combining physical therapy with orthotic treatment.

References:

[1]Tada M, et al. Matrix metalloprotease 3 is associated with sarcopenia in rheumatoid arthritis - results from the CHIKARA study. Int J Rheum Dis. 2018; 21 (11): 1962-9.

[2]Hennessy K, et al. Custom foot orthoses for rheumatoid arthritis: A systematic review. Arthritis Care Res (Hoboken). 2012; 64 (3): 311-20.

Acknowledgments:

This work was supported by JSPS KAKENHI Grant Numbers JP19K11420.

Disclosure of Interests:

None declared

DOI: 10.1136/annrheumdis-2020-eular.3143

Synthetic Lethality with Trifluridine/Tipiracil and Checkpoint Kinase 1 Inhibitor for Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a disease characterized by a high mutation rate of the TP53 gene, which plays pivotal roles in the DNA damage response (DDR) and is regulated by checkpoint kinase (CHK) 2. CHK1 is another key DDR-related protein, and its selective inhibition is suggested to be particularly sensitive to TP53-mutated cancers, because a loss of both pathways (CHK1 and/or CHK2-p53) is lethal due to the serious impairment of DDR. Such a therapeutic strategy is termed synthetic lethality. Here, we propose a novel therapeutic strategy based on synthetic lethality combining trifluridine/tipiracil and prexasertib (CHK1 inhibitor) as a treatment for ESCC. Trifluridine is a key component of the antitumor drug combination with trifluridine/tipiracil (an inhibitor of trifluridine degradation), also known as TAS-102. In this study, we demonstrate that trifluridine increases CHK1 phosphorylation in ESCC cells combined with a reduction of the S-phase ratio as well as the induction of ssDNA damage. Because CHK1 phosphorylation is considered to be induced as DDR for trifluridine-mediated DNA damage, we examined the effects of CHK1 inhibition on trifluridine treatment. Consequently, CHK1 inhibition by short hairpin RNA or treatment with the CHK1 inhibitor, prexasertib, markedly enhanced trifluridine-mediated DNA damage, represented by an increase of γH2AX expression. Moreover, the combination of trifluridine/tipiracil and CHK1 inhibition significantly suppressed tumor growth of ESCC-derived xenograft tumors. Furthermore, the combination of trifluridine and prexasertib enhanced radiosensitivity both in vitro and in vivo Thus, the combination of trifluridine/tipiracil and a CHK1 inhibitor exhibits effective antitumor effects, suggesting a novel therapeutic strategy for ESCC.

Bone strength of the proximal femur in healthy subjects with ossification of the posterior longitudinal ligament

We compared the bone strength measured via quantitative computed tomography-based finite element method (QCT/FEM) between healthy adults with and without ossification of the posterior longitudinal ligament (OPLL). No statistically significant difference was observed in the bone strength between healthy adults with and without OPLL. Hyperostosis of the posterior longitudinal ligament in OPLL may not be associated with the systemic bone strength.

INTRODUCTION

Although patients with OPLL have been reportedly associated with increased level of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA), little is known about the bone strength in OPLL subjects. The aim of this study is to investigate the bone strength measured via QCT/FEM in healthy subjects with OPLL using the medical check-up data, including whole-body CT scans.

METHODS

We examined 796 participants (529 men and 267 women) who underwent CT scans in a single health center between January 2008 and May 2009. We identified OPLL in whole spine and divided the subjects into two groups: non-OPLL and OPLL groups. We calculated the predicted bone strength (PBS) of the proximal femur using QCT/FEM and examined the bone mineral status of the calcaneus using quantitative ultrasound (QUS). We compared the PBS and the QUS parameters between the non-OPLL and OPLL groups.

RESULTS

Seventy-four subjects (9.3%; 57 men and 17 women) were diagnosed with OPLL in the whole spine. The OPLL group was significantly older than the non-OPLL group. No statistically significant difference was observed in the PBS and the QUS parameters between the non-OPLL and OPLL groups in both sexes. Furthermore, no statistically significant difference was noted in the PBS and the QUS parameters between two groups in age- and gender-matched analysis.

CONCLUSIONS

Our results suggest that hyperostosis of the posterior longitudinal ligament in OPLL may not be associated with bone strength and bone mineral status at the extremities.

Experimental model for the irradiation-mediated abscopal effect and factors influencing this effect

Radiotherapy (RT) is the primary treatment for cancer. Ionizing radiation from RT induces tumor damage at the irradiated site, and, although clinically infrequent, may cause regression of tumors distant from the irradiated site-a phenomenon known as the abscopal effect. Recently, the abscopal effect has been related to prolongation of overall survival time in cancer patients, though the factors that influence the abscopal effect are not well understood. The aim of this study is to clarify the factors influencing on abscopal effect. Here, we established a mouse model in which we induced the abscopal effect. We injected MC38 (mouse colon adenocarcinoma) cells subcutaneously into C57BL/6 mice at two sites. Only one tumor was irradiated and the sizes of both tumors were measured over time. The non-irradiated-site tumor showed regression, demonstrating the abscopal effect. This effect was enhanced by an increase in the irradiated-tumor volume and by administration of anti-PD1 antibody. When the abscopal effect was induced by a combination of RT and anti-PD1 antibody, it was also influenced by radiation dose and irradiated-tumor volume. These phenomena were also verified in other cell line, B16F10 cells (mouse melanoma cells). These findings provide further evidence of the mechanism for, and factors that influence, the abscopal effect in RT.

Combination treatment with highly bioavailable curcumin and NQO1 inhibitor exhibits potent antitumor effects on esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most intractable cancers, so the development of novel therapeutics has been required to improve patient outcomes. Curcumin, a polyphenol from Curcuma longa, exhibits various health benefits including antitumor effects, but its clinical utility is limited because of low bioavailability. Theracurmin^® (THC) is a highly bioavailable curcumin dispersed with colloidal submicron particles.

METHODS

We examined antitumor effects of THC on ESCC cells by cell viability assay, colony and spheroid formation assay, and xenograft models. To reveal its mechanisms, we investigated the levels of reactive oxygen species (ROS) and performed microarray gene expression analysis. According to those analyses, we focused on NQO1, which involved in the removal of ROS, and examined the effects of NQO1-knockdown or overexpression on THC treatment. Moreover, the therapeutic effect of THC and NQO1 inhibitor on ESCC patient-derived xenografts (PDX) was investigated.

RESULTS

THC caused cytotoxicity in ESCC cells, and suppressed the growth of xenografted tumors more efficiently than curcumin. THC increased ROS levels and activated the NRF2-NMRAL2P-NQO1 expressions. Inhibition of NQO1 in ESCC cells by shRNA or NQO1 inhibitor resulted in an increased sensitivity of cells to THC, whereas overexpression of NQO1 antagonized it. Notably, NQO1 inhibitor significantly enhanced the antitumor effects of THC in ESCC PDX tumors.

CONCLUSIONS

These findings suggest the potential usefulness of THC and its combination with NQO1 inhibitor as a therapeutic option for ESCC.

Three-Dimensional Organoids Reveal Therapy Resistance of Esophageal and Oropharyngeal Squamous Cell Carcinoma Cells

BACKGROUND & AIMS

Oropharyngeal and esophageal squamous cell carcinomas, especially the latter, are a lethal disease, featuring intratumoral cancer cell heterogeneity and therapy resistance. To facilitate cancer therapy in personalized medicine, three-dimensional (3D) organoids may be useful for functional characterization of cancer cells ex vivo. We investigated the feasibility and the utility of patient-derived 3D organoids of esophageal and oropharyngeal squamous cell carcinomas.

METHODS

We generated 3D organoids from paired biopsies representing tumors and adjacent normal mucosa from therapy-naïve patients and cell lines. We evaluated growth and structures of 3D organoids treated with 5-fluorouracil ex vivo.

RESULTS

Tumor-derived 3D organoids were grown successfully from 15 out of 21 patients (71.4%) and passaged with recapitulation of the histopathology of the original tumors. Successful formation of tumor-derived 3D organoids was associated significantly with poor response to presurgical neoadjuvant chemotherapy or chemoradiation therapy in informative patients (P = 0.0357, progressive and stable diseases, n = 10 vs. partial response, n = 6). The 3D organoid formation capability and 5-fluorouracil resistance were accounted for by cancer cells with high CD44 expression and autophagy, respectively. Such cancer cells were found to be enriched in patient-derived 3D organoids surviving 5-fluorouracil treatment.

CONCLUSIONS

The single cell-based 3D organoid system may serve as a highly efficient platform to explore cancer therapeutics and therapy resistance mechanisms in conjunction with morphological and functional assays with implications for translation in personalized medicine.

IL-6 Mediates Cross-Talk between Tumor Cells and Activated Fibroblasts in the Tumor Microenvironment

The tumor microenvironment (TME) plays a major role in the pathogenesis of multiple cancer types, including upper-gastrointestinal (GI) cancers that currently lack effective therapeutic options. Cancer-associated fibroblasts (CAF) are an essential component of the TME, contributing to tumorigenesis by secreting growth factors, modifying the extracellular matrix, supporting angiogenesis, and suppressing antitumor immune responses. Through an unbiased approach, we have established that IL-6 mediates cross-talk between tumor cells and CAF not only by supporting tumor cell growth, but also by promoting fibroblast activation. As a result, IL-6 receptor (IL6Rα) and downstream effectors offer opportunities for targeted therapy in upper-GI cancers. IL-6 loss suppressed tumorigenesis in physiologically relevant three-dimensional (3D) organotypic and 3D tumoroid models and murine models of esophageal cancer. Tocilizumab, an anti-IL6Rα antibody, suppressed tumor growth in vivo in part via inhibition of STAT3 and MEK/ERK signaling. Analysis of a pan-cancer TCGA dataset revealed an inverse correlation between IL-6 and IL6Rα overexpression and patient survival. Therefore, we expanded evaluation of tocilizumab to head and neck squamous cell carcinoma patient-derived xenografts and gastric adenocarcinoma xenografts, demonstrating suppression of tumor growth and altered STAT3 and ERK1/2 gene signatures. We used small-molecule inhibitors of STAT3 and MEK1/2 signaling to suppress tumorigenesis in the 3D organotypic model of esophageal cancer. We demonstrate that IL6 is a major contributor to the dynamic cross-talk between tumor cells and CAF in the TME. Our findings provide a translational rationale for inhibition of IL6Rα and downstream signaling pathways as a novel targeted therapy in oral-upper-GI cancers.Significance: These findings demonstrate the interaction of esophageal cancer and cancer-associated fibroblasts through IL-6 signaling, providing rationale for a novel therapeutic approach to target these cancers. Cancer Res; 78(17); 4957-70. ©2018 AACR.

Fibroblast growth factor-2-mediated FGFR/Erk signaling supports maintenance of cancer stem-like cells in esophageal squamous cell carcinoma

In esophageal squamous cell carcinoma (ESCC), a subset of cells defined by high expression of CD44 and low expression of CD24 has been reported to possess characteristics of cancer stem-like cells (CSCs). Novel therapies directly targeting CSCs have the potential to improve prognosis of ESCC patients. Although fibroblast growth factor-2 (FGF-2) expression correlates with recurrence and poor survival in ESCC patients, the role of FGF-2 in regulation of ESCC CSCs has yet to be elucidated. We report that FGF-2 is significantly upregulated in CSCs and significantly increases CSC content in ESCC cell lines by inducing epithelial-mesenchymal transition (EMT). Conversely, the FGFR inhibitor, AZD4547, sharply diminishes CSCs via induction of mesenchymal-epithelial transition. Further experiments revealed that MAPK/Erk kinase (Mek)/extracellular signal-regulated kinases (Erk) pathway is crucial for FGF-2-mediated CSC regulation. Pharmacological inhibition of FGF receptor (FGFR)-mediated signaling via AZD4547 did not affect CSCs in Ras mutated cells, implying that Mek/Erk pathway, downstream of FGFR signaling, might be an important regulator of CSCs. Indeed, the Mek inhibitor, trametinib, efficiently suppressed ESCC CSCs even in the context of Ras mutation. Consistent with these findings in vitro, xenotransplantation studies demonstrated that inhibition of FGF-2-mediated FGFR/Erk signaling significantly delayed tumor growth. Taken together, these findings indicate that FGF-2 is an essential factor regulating CSCs via Mek/Erk signaling in ESCC. Additionally, inhibition of FGFR and/or Mek signaling represents a potential novel therapeutic option for targeting CSCs in ESCC.

Alcohol Consumption and Multiple Dysplastic Lesions Increase Risk of Squamous Cell Carcinoma in the Esophagus, Head, and Neck

BACKGROUND & AIMS

Some patients develop multiple squamous cell carcinomas (SCCs) in the upper aerodigestive tract, attributed to field cancerization; alcohol consumption has been associated with this process. We examined the association between multiple areas of dysplastic squamous epithelium with the development of SCC of the esophagus or head and neck cancer, as well as alcohol consumption and smoking.

METHODS

We examined 331 patients with early stage esophageal SCC using Lugol chromoendoscopy to evaluate the dysplastic squamous epithelium in the esophagus. Patients then were assigned to 3 groups, based on the number of Lugol-voiding lesions: A, no lesion; B, 1-9 lesions; or C, 10 or more lesions. Participants completed lifestyle surveys on their history of drinking, smoking, and diet. All participants were evaluated by laryngopharyngoscopy before registration; only those without head and neck cancer were included, except for patients with superficial SCC limited to the subepithelial layer. Lesions detected in the esophagus and head and neck by surveillance were considered to be metachronous. The study end point was the cumulative incidence of metachronous SCCs in the esophagus and head and neck after endoscopic resection of esophageal SCC, according to the grade of Lugol-voiding lesions. At study entry, all patients were instructed to abstain from alcohol and smoking.

RESULTS

Over the 2-year study period, metachronous SCCs of the esophagus were detected in 4% of patients in group A, in 9.4% of patients in group B, and in 24.7% of patients in group C (P < .0001 for patients in group A vs B or B vs C). Head and neck SCCs were detected in none of the patients in group A, in 1.7% of the patients in group B, and in 8.6% of the patients in group C (P = .016 for patients in group A vs C and P = .008 for patients in group B vs C). SCC of the esophagus or head and neck developed in 4.0% of patients in group A, in 10.0% of patients in group B, and in 31.4% of patients in group C (P < .0001 for group A vs B or A vs C). Alcohol abstinence decreased the risk of multiple SCCs of the esophagus (adjusted hazard ratio, 0.47, 95% confidence interval, 0.25-0.91; P = .025), whereas smoking abstinence did not.

CONCLUSIONS

Multiple dysplastic lesions in the esophagus increase the risk of multiple SCCs. Alcohol abstinence reduces the risk of metachronous SCCs. Clinical Trials registry: UMIN000001676 and UMIN000005466.

ALDH2 modulates autophagy flux to regulate acetaldehyde-mediated toxicity thresholds

A polymorphic mutation in the acetaldehyde dehydrogenase 2 (ALDH2) gene has been epidemiologically linked to the high susceptibility to esophageal carcinogenesis for individuals with alcohol use disorders. Mice subjected to alcohol drinking show increased oxidative stress and DNA adduct formation in esophageal epithelia where Aldh2 loss augments alcohol-induced genotoxic effects; however, it remains elusive as to how esophageal epithelial cells with dysfunctional Aldh2 cope with oxidative stress related to alcohol metabolism. Here, we investigated the role of autophagy in murine esophageal epithelial cells (keratinocytes) exposed to ethanol and acetaldehyde. We find that ethanol and acetaldehyde trigger oxidative stress via mitochondrial superoxide in esophageal keratinocytes. Aldh2-deficient cells appeared to be highly susceptible to ethanol- or acetaldehyde-mediated toxicity. Alcohol dehydrogenase-mediated acetaldehyde production was implicated in ethanol-induced cell injury in Aldh2 deficient cells as ethanol-induced oxidative stress and cell death was partially inhibited by 4-methylpyrazole. Acetaldehyde activated autophagy flux in esophageal keratinocytes where Aldh2 deficiency increased dependence on autophagy to cope with ethanol-induced acetaldehyde-mediated oxidative stress. Pharmacological inhibition of autophagy flux by chloroquine stabilized p62/SQSTM1, and increased basal and acetaldehyde-mediate oxidative stress in Aldh2 deficient cells as documented in monolayer culture as well as single-cell derived three-dimensional esophageal organoids, recapitulating a physiological esophageal epithelial proliferation-differentiation gradient. Our innovative approach indicates, for the first time, that autophagy may provide cytoprotection to esophageal epithelial cells responding to oxidative stress that is induced by ethanol and its major metabolite acetaldehyde. Defining autophagymediated cytoprotection against alcohol-induced genotoxicity in the context of Aldh2 deficiency, our study provides mechanistic insights into the tumor suppressor functions of ALDH2 and autophagy in alcohol-related esophageal carcinogenesis.

Novel EGFR-targeted strategy with hybrid peptide against oesophageal squamous cell carcinoma

Epidermal growth factor receptor (EGFR) is a key molecule in the pathophysiology of oesophageal squamous cell carcinoma (OSCC). However, EGFR-targeted agents such as anti-EGFR antibody or tyrosine kinase inhibitors for OSCC have not demonstrated any clinical benefits. Recently, a novel chemotherapeutic agent, EGFR(2R)-lytic hybrid peptide, a composite of EGFR-binding peptide and lytic peptide fragments, has been shown to exhibit a potent anti-tumour effect against cancers that express high EGFR levels. In this study, we investigated the validity of employing EGFR(2R)-lytic hybrid peptide against OSCC cells both in vitro and in vivo. Additionally, the toxicity of this peptide was assessed in mice. We found high EGFR expression levels on the cell surface of OSCC cells, and the EGFR-binding peptide fragment showed high affinity for OSCC cells. A potent cytotoxic effect was induced within 30 minutes by the exposure of OSCC cells to EGFR(2R)-lytic hybrid peptide. Furthermore, EGFR(2R)-lytic hybrid peptide markedly suppressed the tumour growth of OSCC cells in a xenograft model. Moreover, it did not cause any identifiable adverse effects in mice. Taken together, EGFR(2R)-lytic hybrid peptide was shown to be a valid therapeutic agent against OSCC, providing a crucial rationale regarding novel EGFR-targeted therapies against OSCC.

Abstract B31: Establishment of a 5-fluorouracil-resistant esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase gene amplification

5-Fluorouracil (5-FU) is the key drug for the treatment of esophageal squamous cell carcinoma (ESCC), however, resistance to 5-FU remains a critical limitation to the clinical use. To clarify the mechanisms of 5-FU resistance in ESCC, we have established a 5-FU-resistant ESCC cell line TE-5R from parental TE-5 cells, by treatment with the step-wise continuous increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold resistant to 5-FU in comparison with TE-5 cells. Intracellular 5-FU concentration was significantly lower in TE-5R cells than in TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation, whereas copy number of the other 5-FU metabolism-related genes in TE-5R cells did not changed from TE-5 cells. Gimeracil, a DPD inhibitor, sharply restored 5-FU resistance and increased intracellular 5-FU concentration in TE-5R cells. Next, to investigate whether other 5-FU metabolism-related genes contributed to 5-FU resistance in TE-5R cells, we added microarray gene expression assay and no significant differences in the expression of 5-FU metabolism-related genes were detected. These results indicate that 5-FU resistance in TE-5R cells is based on a DPD-dependent rapid degradation of 5-FU. Taken together, we established novel 5-FU-resistant TE-5R cells, which may have obtained 5-FU resistance with DPD copy number amplification and consequent overexpression, providing a critical insight to explore a new strategy against 5-FU-resistant ESCC using DPD inhibitor.

Citation Format: Osamu Kikuchi, Kiichiro Baba, Shinya Ohashi, Manabu Muto. Establishment of a 5-fluorouracil-resistant esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase gene amplification. [abstract]. In: Proceedings of the Fourth AACR International Conference on Frontiers in Basic Cancer Research; 2015 Oct 23-26; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2016;76(3 Suppl):Abstract nr B31.

Recent Advances From Basic and Clinical Studies of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive squamous cell carcinomas and is highly prevalent in Asia. Alcohol and its metabolite, acetaldehyde, are considered definite carcinogens for the esophagus. Polymorphisms in the aldehyde dehydrogenase 2 gene, which encodes an enzyme that eliminates acetaldehyde, have been associated with esophageal carcinogenesis. Studies of the mutagenic and carcinogenic effects of acetaldehyde support this observation. Several recent large-scale comprehensive analyses of the genomic alterations in ESCC have shown a high frequency of mutations in genes such as TP53 and others that regulate the cell cycle or cell differentiation. Moreover, whole genome and whole exome sequencing studies have frequently detected somatic mutations, such as G:C→A:T transitions or G:C→C:G transversions, in ESCC tissues. Genomic instability, caused by abnormalities in the Fanconi anemia DNA repair pathway, is also considered a pathogenic mechanism of ESCC. Advances in diagnostic techniques such as magnifying endoscopy with narrow band imaging or positron emission tomography have increased the accuracy of diagnosis of ESCC. Updated guidelines from the National Comprehensive Cancer Network standardize the practice for the diagnosis and treatment of esophageal cancer. Patients with ESCC are treated endoscopically or with surgery, chemotherapy, or radiotherapy, based on tumor stage. Minimally invasive treatments help improve the quality of life of patients who undergo such treatments. We review recent developments in the diagnosis and treatment of ESCC and advances gained from basic and clinical research.

Abstract 5346: Notch3-mediated squamous cell differentiation shows anti-tumor effect on esophageal squamous cell carcinoma as well as reduces its resistance to 5-Fluorouracil

BACKGROUND: We have shown that Notch3 plays an important role in the regulation of esophageal squamous cell differentiation. However, it remains unclear how Notch3-mediated squamous cell differentiation influences the tumorigenicity of esophageal squamous cell carcinoma (ESCC) or its sensitivity to anti-cancer agents, including 5-Fluorouracil (5-FU).

METHODS: We used 5-FU-resistant human ESCC cells, TE-11R, established by the step-wise continuous exposure of parental TE-11 cells to 5-FU. The TE-11R cells were stably transduced with intracellular domain of Notch3 (ICN3), an active form of Notch3, in a regulatable manner (Tet-On system). The anti-tumor effect of Notch3-overexpression was evaluated by implanting those cells into NOD SCID mice. 5-FU resistance was determined by calculating the 50% inhibitory concentration (IC50) of 5-FU using the WST-1 assay. Gene expression of squamous differentiation markers such as involucrin and cytokeratin 13 (CK13) as well as proliferative activity were determined.

RESULTS: TE-11R cells formed bulky tumors in NOD SCID mice, and the tumor formation rate of TE-11R cells (6/6: 100%) was higher than that of TE-11 cells (1/8: 12.5%). TE-11R-derived tumors showed a less differentiated and more proliferative phenotype represented by fewer ‘keratin pearl’ formations with lower involucrin and Notch3 expressions as well as higher Ki67 expression in comparison with TE-11-derived tumors. Consistent with this, TE-11R cells showed lower gene expressions of Notch3, involucrin, and CK13, and exhibited approximately 1.4-fold higher proliferative activity than parental TE-11 cells in vitro. Notch3 overexpression resulted in the promotion of cell differentiation accompanied by increased expressions of involucrin and CK13, and suppressed cell growth in vitro as well as tumorigenicity in vivo. Finally, it clearly reduced the 5-FU resistance of TE-11R cells in vitro. IC50 values of TE-11R-ICN3 (DOX-) and TE-11R-ICN3 (DOX+) were 96.0 ± 19.7 and 21.6 ± 10.4 μM (P &lt; 0.01), respectively.

CONCLUSION: Our study showed that Notch3-mediated squamous cell differentiation reduced both the tumorigenicity and 5-FU resistance of ESCC cells. We suggest that a strategy to promote squamous cell differentiation may ameliorate the outcome associated with 5-FU-resistant ESCC.

Citation Format: Osamu Kikuchi, Shinya Ohashi, Yukie Nakai, Yusuke Amanuma, Masahiro Yoshioka, Shin'ichi Miyamoto, Mitsuteru Natsuizaka, Hiroshi Nakagawa, Tsutomu Chiba, Manabu Muto. Notch3-mediated squamous cell differentiation shows anti-tumor effect on esophageal squamous cell carcinoma as well as reduces its resistance to 5-Fluorouracil. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5346. doi:10.1158/1538-7445.AM2015-5346

Novel 5-fluorouracil-resistant human esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase overexpression

5-Fluorouracil (5-FU) is a key drug for the treatment of esophageal squamous cell carcinoma (ESCC); however, resistance to it remains a critical limitation to its clinical use. To clarify the mechanisms of 5-FU resistance of ESCC, we originally established 5-FU-resistant ESCC cells, TE-5R, by step-wise treatment with continuously increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold more resistant to 5-FU in comparison with parental TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation. 5-FU treatment resulted in a significant decrease of the intracellular 5-FU concentration and increase of the concentration of α-fluoro-ureidopropionic acid (FUPA), a metabolite of 5-FU, in TE-5R compared with TE-5 cells in vitro. Conversely, gimeracil, a DPD inhibitor, markedly increased the intracellular 5-FU concentration, decreased the intracellular FUPA concentration, and attenuated 5-FU resistance of TE-5R cells. These results indicate that 5-FU resistance of TE-5R cells is due to the rapid degradation of 5-FU by DPD overexpression. The investigation of 5-FU-resistant ESCC with DPYD gene copy number amplification and consequent DPD overexpression may generate novel biological evidence to explore strategies against ESCC with 5-FU resistance.

EGFR inhibitors prevent induction of cancer stem-like cells in esophageal squamous cell carcinoma by suppressing epithelial-mesenchymal transition

There exists a highly tumorigenic subset of esophageal squamous cell carcinoma (ESCC) cells defined by high expression of CD44. A novel therapy targeting these cancer stem-like cells (CSCs) is needed to improve prognosis of ESCC. CSCs of ESCC have a mesenchymal phenotype and epithelial-mesenchymal transition (EMT) is critical to enrich and maintain CSCs. EGFR, frequently overexpressed in ESCC, has pivotal roles in EMT induced by TGF-β in invasive fronts. Thus, EMT in invasive fronts of ESCC might be important for CSCs and EGFR could be a target of a novel therapy eliminating CSCs. However, effects of EGFR inhibitors on CSCs in ESCC have not been fully examined. EGFR inhibitors, erlotinib and cetuximab, significantly suppressed enrichment of CSCs via TGF-β1-mediated EMT. Importantly, EGFR inhibitors sharply suppressed ZEB1 that is essential for EMT in ESCC. Further, EGFR inhibitors activated Notch1 and Notch3, leading to squamous cell differentiation. EGFR inhibition may suppress expression of ZEB1 and induce differentiation, thereby blocking EMT-mediated enrichment of CSCs. In organotypic 3D culture, a form of human tissue engineering, tumor cells in invasive nests showed high expression of CD44. Erlotinib significantly blocked invasion into the matrix and CD44 high expressing CSCs were markedly suppressed by erlotinib in organotypic 3D culture. In conclusion, EMT is a critical process for generation of CSCs and the invasive front of ESCC, where EMT occurs, might form a CSC niche in ESCC. EGFR inhibitors could suppress EMT in invasive fronts and be one therapeutic option targeting against generation of CSCs in ESCC.

Acetaldehyde/ethanol breath test for identifying people at high risk of upper aerodigestive tract cancer

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Background: Alcohol drinking increases the risk of upper aerodigestive tract cancer, and acetaldehyde (a metabolite of alcohol) is a definite carcinogen for this type of cancer. Acetaldehyde is formed mainly by the oxidation of ethanol by alcohol dehydrogenase 1B (ADH1B) and is eliminated by aldehyde dehydrogenase 2 (ALDH2) in the liver. About 50% of Asian people have the ALDH2*2 variant allele, which encodes an inactive enzyme. Those with the ALDH2*2 allele and an alcohol drinking habit are at definite risk of esophageal and head and neck cancers. Genetic testing is the most reliable method for identifying the ALDH2 genotype, but it is not practical for mass screening because of the cost and time. Therefore, we have established a simple method to identify the ALDH2 genotype by analyzing breath samples. Methods: One hundred seven consecutive healthy Japanese volunteers participated in this study. After providing informed consent, participants drank 100 ml of 0.5% ethanol in a single gulp. Breath samples were collected with originally developed simple gasbags before the alcohol was consumed, and 1, 2, and 5 minutes later. The concentrations of acetaldehyde and ethanol in the bag were measured by high-sensitivity gas chromatography. The ALDH2 and ADH1B genotypes of all participants were confirmed using blood DNA. The relationships between acetaldehyde level and genotypes were determined. Results: The frequencies of ALDH2*1/*1, ALDH2*1/*2, and ALDH2*2/*2 were 46.7%, 43.9%, and 9.3%, respectively. The breath acetaldehyde levels at 1 minute after alcohol ingestion were 89.2 (18.1–399.0) ppb in those with ALDH2*1/*1, 346.3 (78.4–1218.4) ppb in those with ALDH2*1/*2, and 537.1 (213.2–1353.8) ppb in those with ALDH2*2/*2. The breath acetaldehyde level was significantly higher in the ALDH2*2 carrier group regardless of the ADH1B genotype (P<0.001). Setting the cutoff for the acetaldehyde/ethanol ratio at 22.3×10–3 to include ALDH2*2 carriers yielded an accuracy for the detection of ALDH2*2 carriers of 96.3% (95% CI: 91.5–96.9%), sensitivity of 100%, and specificity of 92%. Conclusions: Our breath test may be a convenient screening tool for identifying those at high risk of upper aerodigestive tract cancer.

Abstract A74: TGF-β in tumor microenvironment changes a switch of Notch1-mediated signaling to maintain cancer stem-like cells in esophageal squamous cell carcinoma

There exists a highly tumorigenic subset of esophageal squamous cell carcinoma (ESCC) cells defined by high expression of CD44 (CD44H). CD44H cells have cancer stem-like characteristics and as few as ten CD44H cells can form tumors in an athymic nude mouse. Epithelial-mesenchymal transition (EMT) has a critical role to maintain CD44H cells in ESCC. Notch1-mediated signaling may facilitate either EMT or squamous-cell differentiation in a context-dependent manner. However, detailed mechanism how Notch signaling promotes either EMT or differentiation remains unclear. We investigated how TGF-β in tumor microenvironment might influence Notch signaling to maintain CD44H cells via EMT in ESCC. TGF-β promoted EMT and enriched CD44H cells by activating Notch1 and ZEB1 and suppressing Notch3, while in absence of TGF-β, Notch1 rather activated Notch3, one of pivotal transcription factors in keratinocyte differentiation, led to keratinocyte differentiation. Highly conserved binding sites of ZEB1 exist in the 2nd intron of Notch3. ZEB1 induced by TGF-β bound to the 2nd intron of Notch3 and sharply suppressed the Notch3 transcription, confirmed by CHIP and luciferase assay. Thus TGF-β and Notch1 cooperatively promote EMT and maintain tumor initiating cells. TGF-β signaling influences the tumor initiating capacity of ESCC by modulating novel opposing activities of Notch1 and Notch3 in EMT, and may have translational implications.

Citation Format: Mitsuteru Natsuizaka, Shingo Kagawa, Kelly Whelan, Shinya Ohashi, Shunsuke Ohnishi, Goki Suda, Naoya Sakamoto, Anil K. Rustgi, Hiroshi Nakagawa. TGF-β in tumor microenvironment changes a switch of Notch1-mediated signaling to maintain cancer stem-like cells in esophageal squamous cell carcinoma. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A74. doi:10.1158/1538-7445.CHTME14-A74

Preclinical validation of talaporfin sodium-mediated photodynamic therapy for esophageal squamous cell carcinoma

Photodynamic therapy (PDT) kills cancer cells via a photochemical reaction mediated by an oncotropic photosensitizer. Herein, we performed an experimental preclinical study to validate the anti-tumour effect of talaporfin sodium-mediated PDT (t-PDT) for esophageal squamous cell carcinoma (ESCC) cells. We used human ESCC cells derived from various differentiation grades or resistant to 5-fluorouracil (5-FU). The cytotoxic effect of t-PDT was determined by evaluating cell viability, apoptosis and generation of reactive oxygen species (ROS) and DNA double-strand breaks. Furthermore, the anti-tumour effect of t-PDT was assessed using an anchorage-independent cell-growth assay and xenograft transplantation models. t-PDT induced potent cytotoxicity in ESCC cells independent of their differentiation grade or 5-FU resistance. Moreover, t-PDT induced robust apoptosis, as indicated by cell shrinkage, perinuclear vacuolization, nuclear fragmentation and induction of annexin V-positive cells. This apoptotic response was accompanied by concurrent activation of ROS, and induction of DNA double-strand breakage. Importantly, t-PDT suppressed efficiently anchorage-independent cell growth as well as ESCC-xenografted tumor formation. In aggregate, t-PDT showed anti-tumor potential for ESCC cells with various histological grades or chemoresistance, providing a novel translational rationale of t-PDT for the treatment of ESCC.

Impairment of aldehyde dehydrogenase 2 increases accumulation of acetaldehyde-derived DNA damage in the esophagus after ethanol ingestion

Ethanol and its metabolite, acetaldehyde, are the definite carcinogens for esophageal squamous cell carcinoma (ESCC), and reduced catalytic activity of aldehyde dehydrogenase 2 (ALDH2), which detoxifies acetaldehyde, increases the risk for ESCC. However, it remains unknown whether the ALDH2 genotype influences the level of acetaldehyde-derived DNA damage in the esophagus after ethanol ingestion. In the present study, we administered ethanol orally or intraperitoneally to Aldh2-knockout and control mice, and we quantified the level of acetaldehyde-derived DNA damage, especially N(2) -ethylidene-2'-deoxyguanosine (N(2) -ethylidene-dG), in the esophagus. In the model of oral ethanol administration, the esophageal N(2) -ethylidene-dG level was significantly higher in Aldh2-knockout mice compared with control mice. Similarly, in the model of intraperitoneal ethanol administration, in which the esophagus is not exposed directly to the alcohol solution, the esophageal N(2) -ethylidene-dG level was also elevated in Aldh2-knockout mice. This result indicates that circulating ethanol-derived acetaldehyde causes esophageal DNA damage, and that the extent of damage is influenced by knockout of Aldh2. Taken together, our findings strongly suggest the importance of acetaldehyde-derived DNA damage which is induced in the esophagus of individuals with ALDH2 gene impairment. This provides a physiological basis for understanding alcohol-related esophageal carcinogenesis.

Notch receptor inhibition reveals the importance of cyclin D1 and Wnt signaling in invasive esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive forms of squamous cell carcinomas. Common genetic lesions in ESCC include p53 mutations and EGFR overexpression, both of which have been implicated in negative regulation of Notch signaling. In addition, cyclin D1 is overexpressed in ESCC and can be activated via EGFR, Notch and Wnt signaling. To elucidate how these genetic lesions may interact during the development and progression of ESCC, we tested a panel of genetically engineered human esophageal cells (keratinocytes) in organotypic 3D culture (OTC), a form of human tissue engineering. Notch signaling was suppressed in culture and mice by dominant negative Mastermind-like1 (DNMAML1), a genetic pan-Notch inhibitor. DNMAML1 mice were subjected to 4-Nitroquinoline 1-oxide-induced oral-esophageal carcinogenesis. Highly invasive characteristics of primary human ESCC were recapitulated in OTC as well as DNMAML1 mice. In OTC, cyclin D1 overexpression induced squamous hyperplasia. Concurrent EGFR overexpression and mutant p53 resulted in transformation and invasive growth. Interestingly, cell proliferation appeared to be regulated differentially between those committed to squamous-cell differentiation and those invading into the stroma. Invasive cells exhibited Notch-independent activation of cyclin D1 and Wnt signaling. Within the oral-esophageal squamous epithelia, Notch signaling regulated squamous-cell differentiation to maintain epithelial integrity, and thus may act as a tumor suppressor by preventing the development of a tumor-promoting inflammatory microenvironment.