Whole-genome bisulfite sequencing identifies stage- and subtype-specific DNA methylation signatures in pancreatic cancer

In pancreatic ductal adenocarcinoma (PDAC), no recurrent metastasis-specific mutation has been found, suggesting that epigenetic mechanisms, such as DNA methylation, are the major contributors of late-stage disease progression. Here, we performed the first whole-genome bisulfite sequencing (WGBS) on mouse and human PDAC organoid models to identify stage-specific and molecular subtype-specific DNA methylation signatures. With this approach, we identified thousands of differentially methylated regions (DMRs) that can distinguish between the stages and molecular subtypes of PDAC. Stage-specific DMRs are associated with genes related to nervous system development and cell-cell adhesions, and are enriched in promoters and bivalent enhancers. Subtype-specific DMRs showed hypermethylation of GATA6 foregut endoderm transcriptional networks in the squamous subtype and hypermethylation of EMT transcriptional networks in the progenitor subtype. These results indicate that aberrant DNA methylation contributes to both PDAC progression and subtype differentiation, resulting in significant and reoccurring DNA methylation patterns with diagnostic and prognostic potential.

Establishment, characterization, and biobanking of 36 pancreatic cancer organoids: prediction of metastasis in resectable pancreatic cancer

PURPOSE

Early dissemination of primary pancreatic ductal adenocarcinoma (PDAC) is the main cause of dismal prognosis as it highly limits possible treatment options. A number of PDAC patients experience distant metastasis even after treatment due to the metastatic clones. We aimed to demonstrate the molecular architecture of borderline resectable PDAC manifests cancer dissemination of PDAC.

METHODS

Here, 36 organoids isolated from primary tumor masses of PDAC patients with diverse metastatic statues are presented. Whole-exome sequencing and RNA sequencing were performed and drug responses to clinically relevant 18 compounds were assessed.

RESULTS

Our results revealed that borderline resectable PDAC organoids exhibited distinct patterns according to their metastatic potency highlighted by multiple genetic and transcriptional factors and strong variances in drug responses.

CONCLUSIONS

These data suggest that the presence of metastatic PDAC can be identified by integrating molecular compositions and drug responses of borderline resectable PDAC.

ELAVL2 loss promotes aggressive mesenchymal transition in glioblastoma

Glioblastoma (GBM), the most lethal primary brain cancer, exhibits intratumoral heterogeneity and molecular plasticity, posing challenges for effective treatment. Despite this, the regulatory mechanisms underlying such plasticity, particularly mesenchymal (MES) transition, remain poorly understood. In this study, we elucidate the role of the RNA-binding protein ELAVL2 in regulating aggressive MES transformation in GBM. We found that ELAVL2 is most frequently deleted in GBM compared to other cancers and associated with distinct clinical and molecular features. Transcriptomic analysis revealed that ELAVL2-mediated alterations correspond to specific GBM subtype signatures. Notably, ELAVL2 expression negatively correlated with epithelial-to-mesenchymal transition (EMT)-related genes, and its loss promoted MES process and chemo-resistance in GBM cells, whereas ELAVL2 overexpression exerted the opposite effect. Further investigation via tissue microarray analysis demonstrated that high ELAVL2 protein expression confers a favorable survival outcome in GBM patients. Mechanistically, ELAVL2 was shown to directly bind to the transcripts of EMT-inhibitory molecules, SH3GL3 and DNM3, modulating their mRNA stability, potentially through an m6A-dependent mechanism. In summary, our findings identify ELAVL2 as a critical tumor suppressor and mRNA stabilizer that regulates MES transition in GBM, underscoring its role in transcriptomic plasticity and glioma progression.

Antiproliferative Activity of Piceamycin by Regulating Alpha-Actinin-4 in Gemcitabine-Resistant Pancreatic Cancer Cells

Although gemcitabine-based regimens are widely used as an effective treatment for pancreatic cancer, acquired resistance to gemcitabine has become an increasingly common problem. Therefore, a novel therapeutic strategy to treat gemcitabine-resistant pancreatic cancer is urgently required. Piceamycin has been reported to exhibit antiproliferative activity against various cancer cells; however, its underlying molecular mechanism for anticancer activity in pancreatic cancer cells remains unexplored. Therefore, the present study evaluated the antiproliferation activity of piceamycin in a gemcitabine-resistant pancreatic cancer cell line and patient-derived pancreatic cancer organoids. Piceamycin effectively inhibited the proliferation and suppressed the expression of alpha-actinin-4, a gene that plays a pivotal role in tumorigenesis and metastasis of various cancers, in gemcitabine-resistant cells. Long-term exposure to piceamycin induced cell cycle arrest at the G0/G1 phase and caused apoptosis. Piceamycin also inhibited the invasion and migration of gemcitabine-resistant cells by modulating focal adhesion and epithelial-mesenchymal transition biomarkers. Moreover, the combination of piceamycin and gemcitabine exhibited a synergistic antiproliferative activity in gemcitabine-resistant cells. Piceamycin also effectively inhibited patient-derived pancreatic cancer organoid growth and induced apoptosis in the organoids. Taken together, these findings demonstrate that piceamycin may be an effective agent for overcoming gemcitabine resistance in pancreatic cancer.

Patient-derived glioblastoma cell lines with conserved genome profiles of the original tissue

Glioblastoma (GBM) is the most lethal intracranial tumor. Sequencing technologies have supported personalized therapy for precise diagnosis and optimal treatment of GBM by revealing clinically actionable molecular characteristics. Although accumulating sequence data from brain tumors and matched normal tissues have facilitated a comprehensive understanding of genomic features of GBM, these in silico evaluations could gain more biological credibility when they are verified with in vitro and in vivo models. From this perspective, GBM cell lines with whole exome sequencing (WES) datasets of matched tumor tissues and normal blood are suitable biological platforms to not only investigate molecular markers of GBM but also validate the applicability of druggable targets. Here, we provide a complete WES dataset of 26 GBM patient-derived cell lines along with their matched tumor tissues and blood to demonstrate that cell lines can mostly recapitulate genomic profiles of original tumors such as mutational signatures and copy number alterations.

Antiproliferative Activity of Krukovine by Regulating Transmembrane Protein 139 (TMEM139) in Oxaliplatin-Resistant Pancreatic Cancer Cells

Krukovine (KV) is an alkaloid isolated from the bark of Abuta grandifolia (Mart.) Sandw. (Menispermaceae) with anticancer potential in some cancers with KRAS mutations. In this study, we explored the anticancer efficacy and mechanism of KV in oxaliplatin-resistant pancreatic cancer cells and patient-derived pancreatic cancer organoids (PDPCOs) with KRAS mutation. After treatment with KV, mRNA and protein levels were determined by RNA-seq and Western blotting, respectively. Cell proliferation, migration, and invasion were measured by MTT, scratch wound healing assay, and transwell analysis, respectively. Patient-derived pancreatic cancer organoids (PDPCOs) with KRAS mutations were treated with KV, oxaliplatin (OXA), and a combination of KV and OXA. KV suppresses tumor progression via the downregulation of the Erk-RPS6K-TMEM139 and PI3K-Akt-mTOR pathways in oxaliplatin-resistant AsPC-1 cells. Furthermore, KV showed an antiproliferative effect in PDPCOs, and the combination of OXA and KV inhibited PDPCO growth more effectively than either drug alone.

Involvement of cell shape and lipid metabolism in glioblastoma resistance to temozolomide

Temozolomide (TMZ) has been used as standard-of-care for glioblastoma multiforme (GBM), but the resistance to TMZ develops quickly and frequently. Thus, more studies are needed to elucidate the resistance mechanisms. In the current study, we investigated the relationship among the three important phenotypes, namely TMZ-resistance, cell shape and lipid metabolism, in GBM cells. We first observed the distinct difference in cell shapes between TMZ-sensitive (U87) and resistant (U87R) GBM cells. We then conducted NMR-based lipid metabolomics, which revealed a significant increase in cholesterol and fatty acid synthesis as well as lower lipid unsaturation in U87R cells. Consistent with the lipid changes, U87R cells exhibited significantly lower membrane fluidity. The transcriptomic analysis demonstrated that lipid synthesis pathways through SREBP were upregulated in U87R cells, which was confirmed at the protein level. Fatostatin, an SREBP inhibitor, and other lipid pathway inhibitors (C75, TOFA) exhibited similar or more potent inhibition on U87R cells compared to sensitive U87 cells. The lower lipid unsaturation ratio, membrane fluidity and higher fatostatin sensitivity were all recapitulated in patient-derived TMZ-resistant primary cells. The observed ternary relationship among cell shape, lipid composition, and TMZ-resistance may be applicable to other drug-resistance cases. SREBP and fatostatin are suggested as a promising target-therapeutic agent pair for drug-resistant glioblastoma.

Proteogenomic landscape of human pancreatic ductal adenocarcinoma in an Asian population reveals tumor cell-enriched and immune-rich subtypes

We report a proteogenomic analysis of pancreatic ductal adenocarcinoma (PDAC). Mutation-phosphorylation correlations identified signaling pathways associated with somatic mutations in significantly mutated genes. Messenger RNA-protein abundance correlations revealed potential prognostic biomarkers correlated with patient survival. Integrated clustering of mRNA, protein and phosphorylation data identified six PDAC subtypes. Cellular pathways represented by mRNA and protein signatures, defining the subtypes and compositions of cell types in the subtypes, characterized them as classical progenitor (TS1), squamous (TS2-4), immunogenic progenitor (IS1) and exocrine-like (IS2) subtypes. Compared with the mRNA data, protein and phosphorylation data further classified the squamous subtypes into activated stroma-enriched (TS2), invasive (TS3) and invasive-proliferative (TS4) squamous subtypes. Orthotopic mouse PDAC models revealed a higher number of pro-tumorigenic immune cells in TS4, inhibiting T cell proliferation. Our proteogenomic analysis provides significantly mutated genes/biomarkers, cellular pathways and cell types as potential therapeutic targets to improve stratification of patients with PDAC.

Long Non-Coding RNA GAS5 Promotes BAX Expression by Competing with microRNA-128-3p in Response to 5-Fluorouracil

The acquisition of drug resistance is a major hurdle for effective cancer treatment. Although several efforts have been made to overcome drug resistance, the underlying mechanisms have not been fully elucidated. This study investigated the role of long non-coding RNA (lncRNA) growth arrest-specific 5 (GAS5) in drug resistance. GAS5 was found to be downregulated in colon cancer cell lines that are resistant to 5-fluorouracil (5-FU). Downregulation of GAS5 decreased the viability of HCT116 cells and the level of the pro-apoptotic BAX protein, while GAS5 overexpression promoted cell death in response to 5-FU. The interaction between GAS5 and BAX mRNA was investigated using MS2-tagged RNA affinity purification (MS2-trap) followed by RT-qPCR, and the results showed that GAS5 bound to the 3'-untranslated region of BAX mRNA and enhanced its expression by interfering with the inhibitory effect of microRNA-128-3p, a negative regulator of BAX. In addition, ectopic expression of GAS5 increased the sensitivity of resistant cells in response to anti-cancer drugs. These results suggest that GAS5 promoted cell death by interfering with miR-128-3p-mediated BAX downregulation. Therefore, GAS5 overexpression in chemo-resistant cancer cells may be a potential strategy to improve the anti-cancer efficacy of drugs.

Enterotypical Prevotella and three novel bacterial biomarkers in preoperative stool predict the clinical outcome of colorectal cancer

BACKGROUND

A significant proportion of colorectal cancer (CRC) patients suffer from early recurrence and progression after surgical treatment. Although the gut microbiota is considered as a key player in the initiation and progression of CRC, most prospective studies have been focused on a particular pathobionts such as Fusobacterium nucleatum. Here, we aimed to identify novel prognostic bacteria for CRC by examining the preoperative gut microbiota through 16S ribosomal RNA gene sequencing.

RESULTS

We collected stool samples from 333 patients with primary CRC within 2 weeks before surgery and followed up the patients for a median of 27.6 months for progression and 43.6 months for survival. The sequence and prognosis data were assessed using the log-rank test and multivariate Cox proportional hazard analysis. The gut microbiota was associated with the clinical outcomes of CRC patients (P_progress = 0.011, P_decease = 0.007). In particular, the high abundance of Prevotella, a representative genus of human enterotypes, indicated lower risks of CRC progression (P = 0.026) and decease (P = 0.0056), while the occurrence of Alistipes assigned to Bacteroides sp., Pyramidobacter piscolens, Dialister invisus, and Fusobacterium nucleatum indicated a high risk of progression. A microbiota-derived hazard score considering the five prognostic bacteria accurately predicted CRC progression in 1000 random subsamples; it outperformed widely accepted clinical biomarkers such as carcinoembryonic antigen and lymphatic invasion, after adjustment for the clinicopathological stage (adjusted HR 2.07 [95% CI, 1.61-2.64], P = 7.8e-9, C-index = 0.78). PICRUSt2 suggested that microbial pathways pertaining to thiamine salvage and L-histidine degradation underlie the different prognoses.

CONCLUSIONS

The enterotypical genus Prevotella was demonstrated to be useful in improving CRC prognosis, and combined with the four pathobionts, our hazard score based on the gut microbiota should provide an important asset in predicting medical outcomes for CRC patients. Video Abstract.

The telomere maintenance mechanism spectrum and its dynamics in gliomas

Background

The activation of the telomere maintenance mechanism (TMM) is one of the critical drivers of cancer cell immortality. In gliomas, TERT expression and TERT promoter mutation are considered to reliably indicate telomerase activation, while ATRX mutation and/or loss indicates an alternative lengthening of telomeres (ALT). However, these relationships have not been extensively validated in tumor tissues.

Methods

Telomerase repeated amplification protocol (TRAP) and C-circle assays were used to profile and characterize the TMM cross-sectionally (n = 412) and temporally (n = 133) across glioma samples. WES, RNA-seq, and NanoString analyses were performed to identify and validate the genetic characteristics of the TMM groups.

Results

We show through the direct measurement of telomerase activity and ALT in a large set of glioma samples that the TMM in glioma cannot be defined solely by the combination of telomerase activity and ALT, regardless of TERT expression, TERT promoter mutation, and ATRX loss. Moreover, we observed that a considerable proportion of gliomas lacked both telomerase activity and ALT. This telomerase activation-negative and ALT negative group exhibited evidence of slow growth potential. By analyzing a set of longitudinal samples from a separate cohort of glioma patients, we discovered that the TMM is not fixed and can change with glioma progression.

Conclusions

This study suggests that the TMM is dynamic and reflects the plasticity and oncogenicity of tumor cells. Direct measurement of telomerase enzyme activity and evidence of ALT should be considered when defining TMM. An accurate understanding of the TMM in glioma is expected to provide important information for establishing cancer management strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01095-x.

Colon cancer organoids using monoclonal organoids established in four different lesions of one cancer patient reveal tumor heterogeneity and different real-time responsiveness to anti-cancer drugs

Organoid culture technique has been taking center stage as a next-generation ex-vivo model due to advancement of stem cell research techniques. The importance of the laboratory-based ex vivo model has increasingly been recognized for recapitulating histological, and physioglocal conditions of in vivo microenviorment. Accordingly, the use of this technique has also broadened the understanding of intratumoral heterogeneity which is closely associated with varied drug responses observed in patients. Likewise, studies on heterogeneity within a single tumor tissue have drawn much attention. Here, we isolated 15 single clones from 4 tumor organoid lines from 1 patient at a primary passage from one patient. Each organoid line showed variable alterations in both genotype and phenotype. Furthermore, our methodological approach on drug test employing a high-throughput screening system enabled us to pinpoint the optimal time frame for anti-cancer drugs within a single tumor. We propose that our method can effectively reveal the heterogeneity of time-point in drug response, and the most optimal therapeutic strategies for individual patient.

Establishment of Patient-Derived Pancreatic Cancer Organoids from Endoscopic Ultrasound-Guided Fine-Needle Aspiration Biopsies

Background/Aims

Three-dimensional cultures of human pancreatic cancer tissue also known as "organoids" have largely been developed from surgical specimens. Given that most patients present with locally advanced and/or metastatic disease, such organoids are not representative of the majority of patients. Therefore, we used endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) to collect pancreatic cancer tissues from patients with advanced pancreatic cancer to create organoids, and evaluated their utility in pancreatic cancer research.

Methods

Single-pass EUS-FNA samplings were employed to obtain the tissue for organoid generation. After establishment of the organoid, we compared the core biopsy tissues with organoids using hematoxylin and eosin staining, and performed whole exome sequencing (WES) to detect mutational variants. Furthermore, we compared patient outcome with the organoid drug response to determine the potential utility of the clinical application of such organoid-based assays.

Results

Organoids were successfully generated in 14 of 20 tumors (70%) and were able to be passaged greater than 5 times in 12 of 20 tumors (60%). Among them, we selected eight pairs of organoid and core biopsy tissues for detailed analyses. They showed similar patterns in hematoxylin and eosin staining. WES revealed mutations in KRAS, TP53, CDKN2A, SMAD4, BRCA1, and BRCA2 which were 93% homologous, and the mean nonreference discordance rate was 5.47%. We observed moderate drug response correlations between the organoids and clinical outcomes in patients who underwent FOLFIRINOX chemotherapy.

Conclusions

The established organoids from EUS-FNA core biopsies can be used for a suitable model system for pancreatic cancer research.

Wnt/β-Catenin Inhibition by CWP232291 as a Novel Therapeutic Strategy in Ovarian Cancer

The poor prognosis of ovarian cancer patients mainly results from a lack of early diagnosis approaches and a high rate of relapse. Only a very modest improvement has been made in ovarian cancer patient survival with traditional treatments. More targeted therapies precisely matching each patient are strongly needed. The aberrant activation of Wnt/β-catenin signaling pathway plays a fundamental role in cancer development and progression in various types of cancer including ovarian cancer. Recent insight into this pathway has revealed the potential of targeting Wnt/β-catenin in ovarian cancer treatment. This study aims to investigate the effect of CWP232291, a small molecular Wnt/β-catenin inhibitor on ovarian cancer progression. Various in vitro, in vivo and ex vivo models are established for CWP232291 testing. Results show that CWP232291 could significantly attenuate ovarian cancer growth through inhibition of β-catenin. Noticeably, CWP232291 could also s suppress the growth of cisplatin-resistant cell lines and ovarian cancer patient-derived organoids. Overall, this study has firstly demonstrated the anti-tumor effect of CWP232291 in ovarian cancer and proposed Wnt/β-catenin pathway inhibition as a novel therapeutic strategy against ovarian cancer.

Culture and multiomic analysis of lung cancer patient-derived pleural effusions revealed distinct druggable molecular types

Malignant pleural effusion (MPE) is an independent determinant of poor prognostic factor of non-small cell lung cancer (NSCLC). The course of anchorage independent growth within the pleural cavity likely reforms the innate molecular characteristics of malignant cells, which largely accounts for resistance to chemotherapy and poor prognosis after the surgical resection. Nevertheless, the genetic and transcriptomic features with respect to various drug responses of MPE-complicated NSCLC remain poorly understood. To obtain a clearer overview of the MPE-complicated NSCLC, we established 28 MPE-derived lung cancer cell lines which were subjected to genomic, transcriptomic and pharmacological analysis. Our results demonstrated MPE-derived NSCLC cell lines recapitulated representative driver mutations generally found in the primary NSCLC. It also exhibited the presence of distinct translational subtypes in accordance with the mutational profiles. The drug responses of several targeted chemotherapies accords with both genomic and transcriptomic characteristics of MPE-derived NSCLC cell lines. Our data also suggest that the impending drawback of mutation-based clinical diagnosis in evaluating MPE-complicated NSCLS patient responses. As a potential solution, our work showed the importance of comprehending transcriptomic characteristics in order to defy potential drug resistance caused by MPE.

Acquired Resistance Mechanism of EGFR Kinase Domain Duplication to EGFR TKIs in Non-Small Cell Lung Cancer

PURPOSE

Epidermal growth factor receptor kinase domain duplication (EGFR-KDD) is a rare and poorly understood oncogenic mutation in non-small cell lung cancer (NSCLC). We aimed to investigate the acquired resistance mechanism of EGFR-KDD against EGFR-TKIs.

MATERIALS AND METHODS

We identified EGFR-KDD in tumor tissue obtained from a patient with stage IV lung adenocarcinoma and established the patient-derived cell line SNU-4784. We also established several EGFR-KDD Ba/F3 cell lines: EGFR-KDD wild type (EGFR-KDDWT), EGFR-KDD domain 1 T790M (EGFR-KDDD1T), EGFR-KDD domain 2 T790M (EGFR-KDDD2T), and EGFR-KDD both domain T790M (EGFR-KDDBDT). We treated the cells with EGFR tyrosine kinase inhibitors (TKIs) and performed cell viability assays, immunoblot assays, and ENU (N-ethyl-N-nitrosourea) mutagenesis screening.

RESULTS

In cell viability assays, SNU-4784 cells and EGFR-KDDWT Ba/F3 cells were sensitive to 2nd generation and 3rd generation EGFR TKIs. In contrast, the T790M-positive EGFR-KDD Ba/F3 cell lines (EGFR-KDDT790M) were only sensitive to 3rd generation EGFR TKIs. In ENU mutagenesis screening, we identified the C797S mutation in kinase domain 2 of EGFR-KDDBDT Ba/F3 cells. Based on this finding, we established an EGFR-KDD domain 1 T790M/domain 2 cis-T790M+C797S (EGFR-KDDT/T+C) Ba/F3 model, which was resistant to EGFR TKIs and anti-EGFR monoclonal antibody combined with EGFR TKIs.

CONCLUSION

Our study reveals that the T790M mutation in EGFR-KDD confers resistance to 1st and 2nd generation EGFR TKIs, but is sensitive to 3rd generation EGFR TKIs. In addition, we identified that the C797S mutation in kinase domain 2 of EGFR-KDDT790M mediates a resistance mechanism against 3rd generation EGFR TKIs.

Facile discovery of a therapeutic agent for NK-mediated synergistic antitumor effects using a patient-derived 3D platform

Despite the essential roles of natural killer (NK) cells in cancer treatment, the physical barrier and biological cues of the tumor microenvironment (TME) may induce NK cell dysfunction, causing their poor infiltration into tumors. The currently available two-dimensional (2D) cancer-NK co-culture systems hardly represent the characteristics of TME and are not suitable for tracking the infiltration of immune cells and assessing the efficacy of immunotherapy. This study aims to monitor NK-mediated cancer cell killing using a polymer thin film-based, 3D assay platform that contains highly tumorigenic cancer spheroids. A poly(cyclohexyl methacrylate) (pCHMA)-coated surface enables the generation of tumorigenic spheroids from pancreatic cancer patient-derived cancer cells, showing considerable amounts of extracellular matrix (ECM) proteins and cancer stem cell (CSC)-like characteristics. The 3D spheroid-based assay platform allows rapid discovery of a therapeutic agent for synergistic NK-mediated cytotoxicity through imaging-based high-content screening. In detail, the small molecule C19, known as a multi-epithelial-mesenchymal transition pathway inhibitor, is shown to enhance NK activation and infiltration via modulation of the ECM, resulting in synergistic cytotoxicity against cancer spheroids. This 3D biomimetic co-culture assay platform provides promising applications for predicting patient-specific responses to immunotherapy through advanced therapeutic combinations involving a chemical drug and immune cells.

Nuclear HKII-P-p53 (Ser15) Interaction is a Prognostic Biomarker for Chemoresponsiveness and Glycolytic Regulation in Epithelial Ovarian Cancer

Simple Summary

Hexokinase II (HKII) is a key glycolysis enzyme associated with tumorigenesis, but its molecular mechanism and pathophysiological role in chemoresistant ovarian cancer remain elusive. In this study, we delineate the novel mechanism showing that activated phosphorylated-p53 (P-p53 Ser15) is required for the regulation of HKII intracellular trafficking and metabolic regulation in chemosensitive ovarian cancer, but not in chemoresistant ovarian cancer harboring p53 mutation. We have observed that increased nuclear HKII-P-p53 (Ser15) interaction is likely associated with chemosensitivity and better survival outcomes in epithelial ovarian cell lines, human primary epithelial ovarian cancer cells, and tumor sections. Nuclear HKII-P-p53 (Ser15) interaction may function as a promising prognostic biomarker, enabling prediction of patients with poor prognosis for deciding better clinical strategies.

Abstract

In epithelial ovarian cancer (EOC), carboplatin/cisplatin-induced chemoresistance is a major hurdle to successful treatment. Aerobic glycolysis is a common characteristic of cancer. However, the role of glycolytic metabolism in chemoresistance and its impact on clinical outcomes in EOC are not clear. Here, we show a functional interaction between the key glycolytic enzyme hexokinase II (HKII) and activated P-p53 (Ser15) in the regulation of bioenergetics and chemosensitivity. Using translational approaches with proximity ligation assessment in cancer cells and human EOC tumor sections, we showed that nuclear HKII-P-p53 (Ser15) interaction is increased after chemotherapy, and functions as a determinant of chemoresponsiveness as a prognostic biomarker. We also demonstrated that p53 is required for the intracellular nuclear HKII trafficking in the control of glycolysis in EOC, associated with chemosensitivity. Mechanistically, cisplatin-induced P-p53 (Ser15) recruits HKII and apoptosis-inducing factor (AIF) in chemosensitive EOC cells, enabling their translocation from the mitochondria to the nucleus, eliciting AIF-induced apoptosis. Conversely, in p53-defective chemoresistant EOC cells, HKII and AIF are strongly bound in the mitochondria and, therefore, apoptosis is suppressed. Collectively, our findings implicate nuclear HKII-P-p53(Ser15) interaction in chemosensitivity and could provide an effective clinical strategy as a promising biomarker during platinum-based therapy.

Comparison of oncologic outcomes between patients with Lynch syndrome and sporadic microsatellite instability-high colorectal cancer

Purpose

Long-term oncologic differences in outcome between groups of patients with Lynch syndrome (LS) colorectal cancer (CRC) and sporadic CRC with microsatellite instability-high (MSI-H) are the focus of investigation in the current study.

Methods

Patients registered in the Korean Hereditary Tumor Registry and 2 tertiary referral hospitals treated for stage I–III CRC between 2005 and 2015 were retrospectively analyzed. Detection for both groups was performed using pedigree, microsatellite instability, and mismatch repair (MMR) gene testing. Multivariate analyses for overall survival (OS) and disease-free survival (DFS) were conducted.

Results

Cases of LS (n = 77) and sporadic CRC with MSI-H (n = 96) were identified. LS CRC patients were younger in age and displayed tumor sidedness, typically involving left-sided colon and rectum, compared to patients with sporadic CRC with MSI-H. OS and DFS were lower for LS CRC relative to CRC with MSI-H (OS, 72.7% vs. 93.8%, P = 0.001; DFS, 71.4% vs. 88.5%, P = 0.001). In multivariate analyses, tumor sidedness, stage, and chemotherapy were independent factors for OS and DFS. LS CRC was a prognostic factor for poorer OS (hazard ratio, 2.740; 95% confidence interval, 1.003–7.487; P = 0.049), but not DFS.

Conclusion

Our findings indicate that LS CRC is associated with poorer outcomes compared to sporadic CRC with MSI-H, presenting distinct clinical features. In view of the current lack of knowledge on genetic and molecular mechanisms, appropriate management taking into consideration the difficulty of identification of CRC with hypermutable tumors harboring heterogeneity is essential.

Glucose deprivation-induced endoplasmic reticulum stress response plays a pivotal role in enhancement of TRAIL cytotoxicity

Abnormalities of the tumor vasculature result in insufficient blood supply and development of a tumor microenvironment that is characterized by low glucose concentrations, low extracellular pH, and low oxygen tensions. We previously reported that glucose-deprived conditions induce metabolic stress and promote tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced cytotoxicity. In this study, we examined whether the metabolic stress-associated endoplasmic reticulum (ER) stress response pathway plays a pivotal role in the enhancement of TRAIL cytotoxicity. We observed no significant cytotoxicity when human colorectal cancer SW48 cells were treated with various doses of TRAIL (2-100 ng/ml) for 4 h or glucose (0-25 mM) for 24 h. However, a combination of TRAIL and low glucose-induced dose-dependent apoptosis through activation of caspases (-8, -9, and -3). Studies with activating transcription factor 4 (ATF4), C/EBP-homologous protein (CHOP), p53 upregulated modulator of apoptosis (PUMA), or death receptor 5 (DR5)-deficient mouse embryonic fibroblasts or HCT116 cells suggest that the ATF4-CHOP-PUMA axis and the ATF4-CHOP-DR5 axis are involved in the combined treatment-induced apoptosis. Moreover, the combined treatment-induced apoptosis was completely suppressed in BH3 interacting-domain death agonist (Bid)- or Bcl-2-associated X protein (Bax)-deficient HCT116 cells, but not Bak-deficient HCT116 cells. Interestingly, the combined treatment-induced Bax oligomerization was suppressed in PUMA-deficient HCT116 cells. These results suggest that glucose deprivation enhances TRAIL-induced apoptosis by integrating the ATF4-CHOP-PUMA axis and the ATF4-CHOP-DR5 axis, consequently amplifying the Bid-Bax-associated mitochondria-dependent pathway.

Exosomal miR-193a and let-7g accelerate cancer progression on primary colorectal cancer and paired peritoneal metastatic cancer

A metastasis of colorectal cancer is difficult to diagnose, and has a poor prognosis. Therefore, we tried to elucidate the possibility of a diagnostic and prognostic marker. Exosomal miR-193a and let-7g were sorted by miRNA microarray. The expression of miR-193a in the PTM group was lower than that of the primary CRC group, and the expression of let-7g was higher than that of the primary CRC. MMP16 and CDKN1A expression was confirmed respectively for target genes of two miRNAs. When the mimics of these miRNAs were treated with cell lines, both MMP16 and CDKN1A decreased intracellular expression. Cell invasiveness and proliferation were decreased by miR-193a and increased by let-7g. The differences in expression of exosomal miR-193a and let-7g extracted from the plasma of patients were classified as cancer progression indicators. Furthermore, the survival rate decreased in the group with low miR-193a expression and high let-7g expression. Our study confirmed the possibility of using this as a diagnostic and prognostic marker for colorectal cancer by measuring the expression levels of exosomal miR-193a and let-7g in blood.

The role of novel fusion genes in human GIST cell lines derived from imatinib-resistant GIST patients: A therapeutic potential of fusion gene

Gastrointestinal stromal tumor (GIST) is the most common sarcoma in the gastrointestinal (GI) tract. Approximately 85% of the GIST is associated with a c-KIT mutation. A few GISTs show mutations in the gene encoding platelet-derived growth factor receptor alpha (PDGFR α or PDGFRA) without c-KIT gene mutation. GIST without c-KIT or PDGFRA mutations, which called wild type GIST, is about 5-10% of the total GIST. Fusion genes were also reported as one of the factors associated with carcinogenesis and drug resistance. With five cell lines derived from imatinib-resistant patients, novel fusion genes were identified from RNA sequencing and both physiological role and therapeutic potential were elucidated. Next-generation sequencing (NGS) analysis and lentiviral transduction were used to effect of fusion gene on GISTs. All the GIST cell lines carried c-KIT-positivity. Three different fusion gene analysis methods were used to find candidate fusion genes, including EIF3K-ACTN4, SYNCRIP-SNX14 and EXOC2-AK7. A novel interchromosomal fusion gene of the candidates, especially EXOC2-AK7, was confirmed in both tissue and cell line. The transduction of fusion gene increased the proliferation compared with the control group. Additionally, the fusion gene increased wound coverage capability. The fusion gene-transduced cell lines were more sensitive than the control group in the treatment of imatinib. In conclusion, five different imatinib-resistant GIST cell lines including the EXOC2-AK7 fusion gene derived from GIST-R5 represent important research tools for the investigation of cancer cell mechanisms underlying drug resistance and genetic variation. Furthermore, our study may facilitate pre-clinical studies of new therapeutic strategies.

Rationally designed redirection of natural killer cells anchoring a cytotoxic ligand for pancreatic cancer treatment

The emergence of T-cell engineering with chimeric antigen receptors (CARs) has led to attractive therapeutics; however, autologous CAR-T cells are associated with poor clinical outcomes in solid tumors because of low safety and efficacy. Therefore, the aim of our study was to develop a CAR therapy with enhanced cytotoxicity against solid cancer using allogeneic NK cells. In this study, we engineered "off-the-shelf" NK cells to redirect them towards pancreatic ductal adenocarcinoma (PDAC) by improving their target-specific cytotoxic potential. By integrated bioinformatic and clinicopathological analyses, folate receptor alpha (FRα) and death receptor 4 (DR4) were significantly highly expressed in patient-derived tumor cells. The combined expression of FRα and DR4/5 was associated with inferior clinical outcomes, therefore indicating their use as potential targets for biomolecular treatment. Thus, FRα and DR4 expression pattern can be a strong prognostic factor as promising therapeutic targets for the treatment of PDAC. For effective PDAC treatment, allogeneic CAR-NK cells were reprogrammed to carry an apoptosis-inducing ligand and to redirect them towards FRα and initiate DR4/5-mediated cancer-selective cell death in FRα- and DR4/5-positive tumors. As a result, the redirected cytotoxic ligand-loaded NK cells led to a significantly enhanced tumor-selective apoptosis. Accordingly, use of allogeneic CAR-NK cells that respond to FRα and DR4/5 double-positive cancers might improve clinical outcomes based on personal genome profiles. Thus, therapeutic modalities based on allogeneic NK cells can potentially be used to treat large numbers of patients with optimally selective cytotoxicity.

Penta-fluorophenol: a Smiles rearrangement-inspired cysteine-selective fluorescent probe for imaging of human glioblastoma

Two of the most critical factors for the survival of glioblastoma (GBM) patients are precision diagnosis and the tracking of treatment progress. At the moment, various sophisticated and specific diagnostic procedures are being used, but there are relatively few simple diagnosis methods. This work introduces a sensing probe based on a turn-on type fluorescence response that can measure the cysteine (Cys) level, which is recognized as a new biomarker of GBM, in human-derived cells and within on-site human clinical biopsy samples. The Cys-initiated chemical reactions of the probe cause a significant fluorescence response with high selectivity, high sensitivity, a fast response time, and a two-photon excitable excitation pathway, which allows the imaging of GBM in both mouse models and human tissue samples. The probe can distinguish the GBM cells and disease sites in clinical samples from individual patients. Besides, the probe has no short or long-term toxicity and immune response. The present findings hold promise for application of the probe to a relatively simple and straightforward following of GBM at clinical sites.

SORBS1 serves a metastatic role via suppression of AHNAK in colorectal cancer cell lines

Cbl-associated protein (CAP) is encoded by the sorbin and SH3 domain-containing 1 (SORBS1) gene. CAP has been reported to be associated with the actin cytoskeleton, receptor tyrosine kinase signaling and cell adhesion through interactions with various proteins. It may be hypothesized that SORBS1 has numerous unknown functions, which may include providing a favorable condition for metastasis. Although CAP has been demonstrated to possess a number of functions, the role of this protein has only been reported in metabolic signaling pathways and its function in cancer remains to be elucidated. In the present study, SORBS1 expression was detected in colorectal cancer cell lines divided into the primary group and the metastatic group by reverse transcription-quantitative PCR and western blot analysis. In addition, SORBS1 expression was manipulated by vector transfection and lentivirus transduction. The metastatic role of SORBS1, as determined by assessing its effects on cell proliferation and migration, was determined by colony formation assay, cell cycle analysis and Boyden chamber assay. To elucidate the SORBS1-binding protein, immunoprecipitation was performed. Co-localization of SORBS1 and AHNAK nucleoprotein (AHNAK) was identified by confocal microscopy. Notably, the protein expression levels of CAP were higher in SNU-769A and SW480 cells than in SNU-769B and SW620 cells. In addition, the number of colonies in the SORBS1-overexpressing group was significantly increased compared with that of the control group, as determined using the colony formation assay; the SORBS1 overexpression group formed >8-fold more colonies than the control group. The proliferative ability of the SORBS1 overexpression group was also significantly increased compared with the control group over the entire incubation period. Cell migration assays revealed that the number of migrated SORBS1-knockdown cells was reduced compared with the control in both HCT-116 and SNU-C4 cell lines; migration area was decreased to 31 and 26% in HCT-116 and SNU-C4 cell lines, respectively. Consequently, it was confirmed that SORBS1 could form a complex with AHNAK, which functions as a tumor suppressor through inhibition of phosphorylated-ERK and Rho-associated coiled-coil containing protein kinase 1. In conclusion, SORBS1 may serve a crucial role in cancer growth and migration via inhibition of AHNAK expression.

Establishment and characterization of 18 human colorectal cancer cell lines

Colorectal cancer (CRC) represents the third most frequently diagnosed malignancy worldwide and is the second most common cause of tumor-associated mortalities in Korea. Due to the disease’s aggressive behavior, the 5-year survival rate for CRC patients remains unpromising. Well-characterized cell lines have been used as a biological model for studying the biology of cancer and developing novel therapeutics. To assist in vitro studies, 18 CRC cell lines (SNU-1566, SNU-1983, SNU-2172, SNU-2297, SNU-2303, SNU-2353B, SNU-2359, SNU-2373B, SNU-2407, SNU-2423, SNU-2431, SNU-2465, SNU-2493, SNU-2536C, SNU-2621B, SNU-NCC-61, SNU-NCC-376, and SNU-NCC-377) derived from Korean patients were established and characterized in the present study. General characteristics of each cell line including doubling time, in vitro morphology, mutational profiles, and protein expressions of CRC-related genes were described. Whole exome sequencing was performed on each cell line to configure mutational profiles. Single nucleotide variation, frame shift, in-frame deletions and insertions, start codon deletion, and splice stop codon mutation of various genes were found and classified based on their pathogenicity reports. In addition, cell viability was assayed to measure their sensitivities to 24 anti-cancer drugs including anti-metabolites, kinase inhibitors, histone deacetylase inhibitors, alkylating inhibitors, and topoisomerase inhibitors, all widely used for various cancers. On testing, five CRC cell lines showed MSI, of which MLH1 or MSH6 gene was mutated. These newly established CRC cell lines can be used to investigate biological characteristics of CRC, particularly for investigating gene alterations associated with CRC.

Maternal exposures to persistent organic pollutants are associated with DNA methylation of thyroid hormone-related genes in placenta differently by infant sex

Exposure to persistent organic pollutants (POPs) during pregnancy is associated with a disruption in thyroid hormone balance. The placenta serves as an important environment for fetal development and also regulates thyroid hormone supply to the fetus. However, epigenetic changes of thyroid regulating genes in placenta have rarely been studied. This study was conducted to evaluate the association between several POP concentrations in maternal serum and DNA methylation of thyroid hormone-related genes in the placenta. The placenta samples were collected from 106 Korean mother at delivery, and the promoter methylation of the placental genes was measured by a bisulfite pyrosequencing. The deiodinase type 3 (DIO3), monocarboxylate transporter 8 (MCT8), and transthyretin (TTR) genes were selected as the target genes as they play an important role in the regulation of fetal thyroid balance. Because people are exposed to multiple chemicals at the same time, a multiple-POP model using principal component analysis (PCA) was applied to evaluate the association between the multiple POPs exposure and the epigenetic change in placenta. In addition, a single-POP model which includes one chemical each in the statistical model for association was conducted. Based on the single-POP models, serum concentrations of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and brominated diphenyl ether-47 (BDE-47) were significantly associated with an increase in placental DIO3 methylation, but only among female infants. Among male infants, a positive association between serum p,p'-DDT and MCT8 methylation level was found. According to the multiple-POP models, serum DDTs were positively associated with DIO3 methylation in the placenta of female infants, while a positive association with MCT8 methylation was observed in those of the male infants. Our observation showed that in utero exposure to DDTs may influence the DNA methylation of DIO3 and MCT8 genes in the placenta, in a sexually dimorphic manner. These alterations in placental epigenetic regulation may in part explain the thyroid hormone disruption observed among the newborns or infants followed by in utero exposure to POPs.

Identification of a Novel Fusion Gene, FAM174A-WWC1, in Early-Onset Colorectal Cancer: Establishment and Characterization of Four Human Cancer Cell Lines from Early-Onset Colorectal Cancers

Colorectal cancer (CRC) is the third most common cancer diagnosed worldwide and represents the second most common cause of all cancer-related deaths in Korea. Although epidemiological data indicate a sharp increase in the incidence of CRC among individuals older than 50 years, more than 10% of CRCs occur before reaching 50. These are known as early-onset CRCs (EOCRCs) and are likely to be suggestive of hereditary predisposition. However, known familial CRC syndromes account for only 20% of genetic aberrations of EOCRC, and the remaining 80% are still in question. Therefore, we aimed to establish reproducible biological resources and contribute to expand the mutation database of EOCRC. Four cell lines derived from the original tumor mass of CRC patients diagnosed under age 30 years were established, and next-generation sequencing technique was used to identify the genetic features of EOCRC. We have identified one novel fusion gene, FAM174A-WWC1, and analyzed its functional role. The induction of FAM174A-WWC1 to normal fibroblast caused alternations in cellular morphology as well as intercellular expression of E-cadherin and N-cadherin. Moreover, WWC1 carrying the fused FAM174A domain not only abrogated the membrane expression of YAP1 but also significantly increased the levels of nucleic YAP1. As a result, the FAM174A-WWC1 expression increased the oncogenic capacity and invasiveness of normal fibroblasts, which suggests its role as a potential driver mutation of EOCRC.

Prenatal exposure to persistent organic pollutants and methylation of LINE-1 and imprinted genes in placenta: A CHECK cohort study

Prenatal exposure to persistent organic pollutants (POPs) has been linked to numerous adverse birth outcomes among newborn infants in many epidemiological studies. Although epigenetic modifications have been suggested as possible explanations for those associations, studies have rarely reported a relationship between POP exposure during pregnancy and DNA methylation in the placenta. In the present study, we investigated the association between prenatal exposure to several POPs, including organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), and methylation levels of long interspersed element 1 (LINE-1), as well as imprinted genes in placental DNAs among Korean mother-child pairs (N = 109). We assessed the association of DNA methylation not only with each target POP (single-POP models) but also with multiple POPs applying principal component analysis (multiple-POP models). Potential associations between placental DNA methylation and birth outcomes of newborn infants were also estimated. In single-POP models, significant associations were detected between OCP measurements and placental DNA methylation. Elevated concentrations of β-hexachlorhexane (β-HCH) in maternal serum collected during delivery were significantly associated with a decrease in methylation of LINE-1 in the placenta. Higher levels of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) in maternal serum were associated with hypermethylation of insulin-like growth factor 2 (IGF2). In multiple-POP models, a significant and positive association between DDTs and IGF2 methylation was also observed. Placental LINE-1 methylation was inversely associated with birth length. Our observations indicate that prenatal exposure to several POPs including DDTs is associated with the changes in methylation of genes, including major imprinted genes in the placenta. The consequences of these epigenetic alterations in placenta during development deserve further investigation.

Establishment and Characterization of Paired Primary and Peritoneal Seeding Human Colorectal Cancer Cell Lines: Identification of Genes That Mediate Metastatic Potential

Peritoneal metastasis is one of the major patterns of unresectability in colorectal cancer (CRC) and a cause of death in advanced CRC. Identification of distinct gene expressions between primary CRC and peritoneal seeding metastasis is to predict the metastatic potential of primary human CRC. Three pairs of primary CRC (SNU-2335A, SNU-2404A, and SNU-2414A) and corresponding peritoneal seeding (SNU-2335D, SNU-2404B, and SNU-2414B) cell lines were established to determine the different gene expressions and resulting aberrated signaling pathways in peritoneal metastasis tumor using whole exome sequencing and microarray. Whole exome sequencing detected that mutation in CYP2A7 was exclusively shared in peritoneal seeding cell lines. Microarray identified that there were five upregulated genes (CNN3, SORBS1, BST2, EPSTI1, and KLHL5) and two downregulated genes (TRY6 and STYL5) in the peritoneal metastatic cell lines. CNN3 expression was highly augmented in both mRNA and protein levels in peritoneal metastasis cells. Knockdown of Calponin 3 resulted in augmented level of E-cadherin in peritoneal metastasis cells, and migration and invasiveness decreased accordingly. We suggest that CNN3 takes part in cell projection and movement, and the detection and distribution of CNN3 may render prognostic information for predicting peritoneal seeding metastasis from primary colorectal cancer.

Abstract 1175: The establishment of single colorectal cancer organoid clones derived from regional biopsies for studying tumor heterogeneity

Nowadays, there is a spotlight on organoid culture, which is cultivated in 3D by using specimens derived from human or another mammalian. In addition, in the process of testing and screening anticancer drugs in vitro, the limitations of 2D culture have been pointed out because homogenous culture condition does not sufficiently represent the real environment in human body. Simultaneously, there has been consensus that 3D models such as spheroids and organoids are more physiologically similar to in vivo system when compared to 2D. In fact, tumor tissue grows in 3D and in heterogenous environment including extra-cellular matrix, immune cells and various lineage of cells differentiated from stem cells. To further comprehend complex in vivo tumor development pathway, new experimental model for mimicking real three-dimensional biopsy has been required and successfully become a part of biological field. Accordingly, organoid culture technic as an emerging next generation ex-vivo model has drawn tremendous attention for its advantages in lots of experimental and therapeutic application. Thus, we have established organoid (3D) lines by isolating tumor epithelium from colon cancer patient tissue and to look into the heterogenous environment of human intestine as well as investigating sensitivity in response to various stimulations such as anti-cancer reagents treatment and irradiation (professors Seung-Yong Jeong and Ji-Won Park contributed this work). And in particular, six to eight single organoids were isolated from the primary passage in each regional biopsy. 4 tumor tissues and 6 to 8 single organoids were obtained from a patient and each biopsy, respectively. In sum, more than 30 organoid lines from one patient were established and cultured to confirm both heterogeneity among regional biopsies and single organoids derived from each biopsy. Each single organoid was successfully isolated by using micromanipulator and micropipette without contamination. Then, we confirmed whether single clones were solely isolated. Furthermore, during the process of expansion of each organoid population, we observed differences in morphology and proliferation rate among organoid lines. However, distinct mechanisms that mainly influences on the tumor heterogeneity are still not fully understood. The technic of single organoid clone isolation could give insights for further studies on investigating heterogeneity among regional tumor biopsies.

Citation Format: Myoung-Hyun Song, Ja-Lok Ku. The establishment of single colorectal cancer organoid clones derived from regional biopsies for studying tumor heterogeneity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1175.

Identification of genes inducing resistance to ionizing radiation in human rectal cancer cell lines: re-sensitization of radio-resistant rectal cancer cells through down regulating NDRG1

Background

Resistance to preoperative radiotherapy is a major clinical problem in the treatment for locally advanced rectal cancer. The role of NDRG1 in resistance to ionizing radiation in rectal cancer has not been fully elucidated. This study aimed to investigate the effect of the reduced intracellular NDRG1 expression on radio-sensitivity of human rectal cancer cells for exploring novel approaches for treatment of rectal cancer.

Methods

Three radio-resistant human rectal cancer cell lines (SNU-61R80Gy, SNU-283R80Gy, and SNU-503R80Gy) were established from human rectal cancer cell lines (SNU-61, SNU-283, and SNU-503) using total 80 Gy of fractionated irradiation. Microarray analysis was performed to identify differently expressed genes in newly established radio-resistant human rectal cancer cells compared to parental rectal cancer cells.

Results

A microarray analysis indicated the RNA expression of five genes (NDRG1, ERRFI1, H19, MPZL3, and UCA1) was highly increased in radio-resistant rectal cancer cell lines. Short hairpin RNA-mediated silencing of NDRG1 sensitized rectal cancer cell lines to clinically relevant doses of radiation by causing more DNA double strand breakages to rectal cancer cells when exposed to radiation.

Conclusions

Targeting NDRG1 represents a promising strategy to increase response to radiotherapy in human rectal cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4514-3) contains supplementary material, which is available to authorized users.

Abstract 4862: SORBS1-AHNAK complex regulates metastatic properties of cancer

Purpose: CAP encoded by SORBS1, Vinexin and ArgBP2 is participated in the SoHo family of proteins. The SoHo protein interacts with different signaling molecules and involves with cell migration, and has been implicated in a variety of cellular processes including insulin-stimulated glucose transport. CAP has specific role in the stabilization of adhesion complexes and the consequent effect of cell migration. It is possible that CAP or complex between CAP and other proteins induces change of cancer cell characters. We assumed that SORBS1 has substantial role of cell proliferation, migration and interaction with other subcellular proteins.

Methods and materials: To elucidate endogenous role of SORBS1, colorectal cancer cell lines were manipulated by pcDNA, siRNA and shRNA in some colorectal cancer cell lines. Function of SORBS1 as regulator of cancer proliferation was demonstrated by cell cycle assay. And several methods including western blotting, cell migration assay and immunoprecipitation assay were performed for determining role of SORBS1 related other metastatic properties.

Conclusion: Colony formation ability and proliferation were induced by SORBS1-overexpression in HT29 cell line. In contrast, transient suppression of SORBS1 inhibits cell proliferation. Moreover, when SORBS1 was constantly suppressed in HCT-116 and SNU-C4 cell line, cell migration was impeded. According to immunoprecipitation data, we chose the AHNAK protein as the convincing candidate protein related with SORBS1. An interaction of SORBS1 and AHNAK was observed in both cytoplasm and nucleus. Expression level of SORBS1 and AHNAK was also negative correlation in extraction of cytoplasm and nucleus.

SORBS1 and AHNAK bind each other as form of protein complex, however, AHNAK known as nucleoprotein is abundant in both cytoplasm and nucleus when SORBS1 is suppressed. Consequently, these results indicate that SORBS1 has a key role of cancer cell growth and invasiveness through regulation of AHNAK expression and degradation.

Note: This abstract was not presented at the meeting.

Citation Format: Woo-Cheol Cho, Ji-Eun Jang, Ja-Lok Ku. SORBS1-AHNAK complex regulates metastatic properties of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4862. doi:10.1158/1538-7445.AM2017-4862

Abstract 2439: Establishment of six human colorectal cancer cell lines: identification of genes that have metastatic potential

A number of genes have been studied in accordance with their metastatic potential. Nevertheless, widely used metastatic colorectal cancer cell lines such as SW-620 or IS3 only show the influence of metastatic genes within limited mutational landscape. Here, three pairs of primary CRC (SNU-2335A, SNU-2335D, SNU-2404A, SNU-2404B, SNU-2414A, and SNU-2414B) and corresponding metastasis cell lines were established and analyzed by whole exome sequencing and microarray.

Three pairs of primary CRC (SNU-2335A, SNU-2404A, and SNU-2414A) and corresponding matched metastasis cell lines (SNU-2335D, SNU-2404B, and SNU-2414B) were analyzed for gene expression by microarray and whole exome sequencing. Selected target genes from microarray were analyzed again by real-time PCR in order to confirm the mRNA expression level in the paired CRC cell lines.

The genes selected for examination were calponin 3, acidic (CNN3); sorbin and SH3 domain containing 1(SORBS1); epithelial stromal interaction 1 (EPSTI1); bone marrow stromal cell antigen 2(BST2); kelch-like 5 (KLHL5); trypsinogen C (TRY6); and synaptotagmin-like 5 (SYTL5). We calculated the intersection of all three metastatic CRC cell lines. Five genes (BST2, SORBS1, CNN3, EPSTI1, and KLHL5) were up-regulated in metastatic cell lines compared to primary cell lines. Two genes (TRY6 and SYTL5) were down-regulated in metastatic cell lines compared to primary cell lines. Then, we ranked 15 genes that were up-regulated and 15 genes that were down-regulated in omental metastasis regardless of the 2-folds threshold. Of the 30 genes that were differently expressed, we selected three genes (CNN3, SORBS1, and TRY6) that showed the highest fold changes and are found in 2-fold change analysis.

We identified 7 genes that were differently expressed in metastatic CRC cell lines compared to primary CRC cell lines. These genes may serve as diagnostic markers and therapeutic targets for patients with metastatic CRC.

Note: This abstract was not presented at the meeting.

Citation Format: Soon-Chan Kim, Chang-Won Hong, Sang-Geun Jang, Seung-Yong Jeong, Jae-Gahb Park, Ja-Lok Ku. Establishment of six human colorectal cancer cell lines: identification of genes that have metastatic potential [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2439. doi:10.1158/1538-7445.AM2017-2439

Clonal History and Genetic Predictors of Transformation Into Small-Cell Carcinomas From Lung Adenocarcinomas

Purpose Histologic transformation of EGFR mutant lung adenocarcinoma (LADC) into small-cell lung cancer (SCLC) has been described as one of the major resistant mechanisms for epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, the molecular pathogenesis is still unclear. Methods We investigated 21 patients with advanced EGFR-mutant LADCs that were transformed into EGFR TKI-resistant SCLCs. Among them, whole genome sequencing was applied for nine tumors acquired at various time points from four patients to reconstruct their clonal evolutionary history and to detect genetic predictors for small-cell transformation. The findings were validated by immunohistochemistry in 210 lung cancer tissues. Results We identified that EGFR TKI-resistant LADCs and SCLCs share a common clonal origin and undergo branched evolutionary trajectories. The clonal divergence of SCLC ancestors from the LADC cells occurred before the first EGFR TKI treatments, and the complete inactivation of both RB1 and TP53 were observed from the early LADC stages in sequenced tumors. We extended the findings by immunohistochemistry in the early-stage LADC tissues of 75 patients treated with EGFR TKIs; inactivation of both Rb and p53 was strikingly more frequent in the small-cell-transformed group than in the nontransformed group (82% v 3%; odds ratio, 131; 95% CI, 19.9 to 859). Among patients registered in a predefined cohort (n = 65), an EGFR mutant LADC that harbored completely inactivated Rb and p53 had a 43× greater risk of small-cell transformation (relative risk, 42.8; 95% CI, 5.88 to 311). Branch-specific mutational signature analysis revealed that apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC)-induced hypermutation was frequent in the branches toward small-cell transformation. Conclusion EGFR TKI-resistant SCLCs are branched out early from the LADC clones that harbor completely inactivated RB1 and TP53. The evaluation of RB1 and TP53 status in EGFR TKI-treated LADCs is informative in predicting small-cell transformation.

Abstract 1640: SORBS1-related multiprotein complex regulates metastasis of cancer

Purpose: CAP (Cbl-associated protein), also known as Sorbin and SH3 domain-containing protein 1 is encoded by the SORBS1 gene. These proteins contain a conserved sorbin homology (SOHO) domain and three SH3 domains. CAP is an adaptor protein that has been associated with the actin cytoskeleton, signaling through receptor tyrosine kinases and cell adhesion. Although, CAP is proven to have many known functions, this protein is only reported in specific field of signaling pathway. Cell adhesion and actin dynamics which have been supposed to participate in CAP are crucial factors of cancer metastasis. The role of CAP has been described in the literature, although their specific roles remain to be clarified in cancer.

Methods and materials: Colorectal cancer cell lines were transduced by lentivirus containing shRNA plasmid (shSORBS1 plasmid). To elucidate function of SORBS1 as regulator of cancer metastasis, western blotting, cell migration assay and immunoprecipitation assays were performed.

Conclusion: According to the several reports of SORBS1 function, phosphorylation of ERK and mTOR was identified. Although ERK phosphorylation were not changed in normal condition, there were different aspects between control group and SORBS1 knockdown group with insulin treatment. Moreover, mTOR phosphorylation of SORBS1 knockdown group was less in the control group than in the normal condition.

Immunoprecipitation of SORBS1 was performed to search for the binding compounds. We chose the AHNAK protein as the convincing candidate protein related with SORBS1. Several studies reported that AHNAK protein is related to proliferation and EMT by binding of specific signaling molecules. Indeed, there were remarkable differences of invasiveness ability between control group and knockdown group.

Citation Format: Woo-Cheol Cho, Ja-Lok Ku. SORBS1-related multiprotein complex regulates metastasis of cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1640.

Abstract 1642: Calponin-3, acidic (CNN3) mediates EMT-related genes in human colorectal cancer metastasis

(a) An introductory sentence indicating the purposes of the study Distant metastasis is the major cause of cancer-related death in colorectal cancer (CRC) patients. Although the Calponin family has emerged as a distinguishing feature in epithelial-to-mesenchymal transition (EMT) in human cancer, the role of CNN3 member in the metastatic CRC has not been investigated.

(b) A brief description of pertinent experimental procedures. Three pairs of primary CRC and corresponding matched metastasis cell lines were analyzed for gene expression by microarray and western blotting. CNN3 was transduced to CRC cell line with lower CNN3 expression level (SW-480), and CNN3 with higher CNN3 expression CRC cell lines (SW-620, HCT-116) was suppressed by lentiviral-induced shRNA. Functional analysis of CNN3 overexpression and suppression was investigated in these CRC cell lines for proliferation and invasion. Expression of several potential CNN3 target genes (ERK1/2) and EMT markers (E-cadherin and vimentin) in primary CRC and matching metastasis CRC cell lines was validated.

(c) A summary of the new, unpublished data. Global CNN3 expression levels were significantly higher in metastasis cell lines compared with the matched primary cell lines in both mRNA (FC = 2.3, p = 0.017) and protein levels. CRC cell lines with suppressed CNN3 showed decreased cell proliferation and reduced invasive behavior in CRC cell lines. Suppression of CNN3 in CRC cell lines with higher CNN3 expression resulted in increased E-cadherin and decreased vimentin. pERK1/2 were decreased in accordance with suppression of CNN3 in both SW-620 and HCT-116. Overexpression of CNN3 in CRC cell lines caused reduced E-cadherin in SW-480 and HT-29.

(d) A statement of the conclusions CNN3 is involved in mediating EMT and metastatic behavior in the colon. Its expression is accordantly related to EMT markers, and CNN3 may serve as a possible diagnostic marker and therapeutic target for patients with CRC.

Citation Format: Soon-Chan Kim, Chang-Won Hong, Sang-Geun Jang, Yeh-Ah Kim, Seung-Yong Jung, Jea-Gab Park, Ja-Lok Ku. Calponin-3, acidic (CNN3) mediates EMT-related genes in human colorectal cancer metastasis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1642.

Improving gastric cancer preclinical studies using diverse in vitro and in vivo model systems

BACKGROUND

"Biomarker-driven targeted therapy," the practice of tailoring patients' treatment to the expression/activity levels of disease-specific genes/proteins, remains challenging. For example, while the anti-ERBB2 monoclonal antibody, trastuzumab, was first developed using well-characterized, diverse in vitro breast cancer models (and is now a standard adjuvant therapy for ERBB2-positive breast cancer patients), trastuzumab approval for ERBB2-positive gastric cancer was largely based on preclinical studies of a single cell line, NCI-N87. Ensuing clinical trials revealed only modest patient efficacy, and many ERBB2-positive gastric cancer (GC) patients failed to respond at all (i.e., were inherently recalcitrant), or succumbed to acquired resistance.

METHOD

To assess mechanisms underlying GC insensitivity to ERBB2 therapies, we established a diverse panel of GC cells, differing in ERBB2 expression levels, for comprehensive in vitro and in vivo characterization. For higher throughput assays of ERBB2 DNA and protein levels, we compared the concordance of various laboratory quantification methods, including those of in vitro and in vivo genetic anomalies (FISH and SISH) and xenograft protein expression (Western blot vs. IHC), of both cell and xenograft (tissue-sectioned) microarrays.

RESULTS

The biomarker assessment methods strongly agreed, as did correlation between RNA and protein expression. However, although ERBB2 genomic anomalies showed good in vitro vs. in vivo correlation, we observed striking differences in protein expression between cultured cells and mouse xenografts (even within the same GC cell type). Via our unique pathway analysis, we delineated a signaling network, in addition to specific pathways/biological processes, emanating from the ERBB2 signaling cascade, as a potential useful target of clinical treatment. Integrated analysis of public data from gastric tumors revealed frequent (10 - 20 %) amplification of the genes NFKBIE, PTK2, and PIK3CA, each of which resides in an ERBB2-derived subpathway network.

CONCLUSION

Our comprehensive bioinformatics analyses of highly heterogeneous cancer cells, combined with tumor "omics" profiles, can optimally characterize the expression patterns and activity of specific tumor biomarkers. Subsequent in vitro and in vivo validation, of specific disease biomarkers (using multiple methodologies), can improve prediction of patient stratification according to drug response or nonresponse.

Abstract A13: Establishment and characterization of patient-derived xenograft models of gastrointestinal stromal tumor resistant to standard tyrosine kinase inhibitors

BACKGROUND: The prognosis of gastrointestinal stromal tumor (GIST) has been dramatically improved after introduction of imatinib which can inhibit the driver mutated oncoproteins,KIT or PDGFRa. However, most patients eventually develop resistance to the tyrosine kinase inhibitors (TKIs) targeting these oncoproteins including imatinib, sunitinib, or regorafenib. The paucity of TKIs-resistant commercially available GIST cell lines hampers development of effective therapy for drug-resistant GIST. Therefore, we established patient-derived xenograft (PDX) models that faithfully recapitulate the genetic and phenotypic features of drug-resistant GIST.

METHODS: PDXs have been established in NOD-SCID mice with tumor fragments of patients with metastatic and/or unresectable GIST after failure of at least imatinib and/or sunitinib. The histological and genomic similarities between all xenografts and the parental tumors have been confirmed using H&E and KIT staining, and short tandem repeat (STR) analysis, respectively. Mutation was detected by whole exome sequencing of patients' tumors on a HiSeq2000 and validated by Sanger sequencing of patients tumors and PDXs. After sequential passaging to BALB/c nude mouse, drug sensitivity assay (imatininb, sunitinib, and regorafenib) was conducted in established PDX models along with Western blotting regarding to KIT and FGFR signaling pathway. As an imatinib-sensitive control model, a xenograft established with GIST-T1 cell line was used.

RESULTS: Three GIST PDX models were established from an imatinib/sunitinib/sorafenib-resistant GIST harboring KIT exon 11 (p.Y570-L576del) and 17 (p.D816E) mutations (AMC-GX1), an imatinib-resistant GIST harboring KIT exon 11 (p.K550_K558del) and 14 (p.T670I) mutations (AMC-GX2), and an imatinib/sunitinib-resistant GIST harboring KIT exon 11 (p.565-577GNNYVVIDPTQLP>Q) and 17 (p.D820Y) mutations (AMC-GX3). Histologic and genetic similarities were confirmed between primary patients' tumors and PDXs. The mutation status of GIST PDXs was consistent with primary tumors. The GIST PDX models showed TKI sensitivity profiles comparable to clinical responses in patients. At day 21 after treatmemt with imatinib, tumor growth was inhibited by 17.8, 53.9, and 12.6% in AMC-GX1, GX2, and GX3, respectively, while by 80.0% in GIST-T1 xenografts. Western blotting analysis showed that KIT phosphorylation was inhibited by imatinib treatment in AMC-GX1 similar to GIST-T1, but not in AMC-GX2 and AMC-GX3. In contrast to GIST-T1, PI3K downstream of KIT was not inhibited with imatinib in AMC-GX1, GX2, and GX3. In addition, TKIs-resistant PDX models showed FGFR1 activation at baseline which was not evident in GIST-T1 xenografts.

CONCLUSION: We have established 3 TKI-resistant GIST PDX models harboring variable KIT mutations which show different KIT and FGFR signaling features from imatinib-sensitive models. The established GIST PDX models will play a role for further studies on mechanisms of resistance to TKI and evaluation of novel targeted therapies in GIST.

Citation Format: Young-Soon Na, Min-Hee Ryu, Sook Ryun Park, Ju-Kyung Lee, Hanui Kim, Chae-Won Lee, Sun Young Lee, Young-Kyoung Shin, Ja-Lok Ku, Sung-Min Ahn, Yoon-Koo Kang. Establishment and characterization of patient-derived xenograft models of gastrointestinal stromal tumor resistant to standard tyrosine kinase inhibitors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A13.

Correlation between the promoter methylation status of ATP-binding cassette sub-family G member 2 and drug sensitivity in colorectal cancer cell lines

Resistance to chemotherapeutic agents has been considered as a major reason for the high incidence rate of recurrence and metastasis suffered by colorectal cancer (CRC) patients. ATP-binding cassette sub-family G member 2 (ABCG2) is involved in drug resistance. DNA methylation of the ABCG2 promoter site has a significant influence on the regulation of epigenetic gene expression. In the present study, we investigated whether the methylation status of the ABCG2 promoter is related to drug sensitivity in CRC cell lines. In order to examine the ABCG2 expression level and identify the methylation status, RT-PCR, qRT-PCR analysis, MS-PCR and bisulfite sequencing were conducted on 32 CRC cell lines. SNU-C4, LS174T and NCI-H716 were selected as low ABCG2-expressing and high promoter methylated cell lines. The cell proliferation assay for 5-fluorouracil, oxaliplatin and irinotecan was performed after 5-aza-2'-deoxycytidine (5-aza) treatment in these cell lines. In the 32 CRC cell lines, 25% of the cell lines expressed low or no ABCG2 expression. Of these cell lines, SNU-C4, LS174T and NCI-H716 were hypermethylated at the promoter region, ~20%. Demethylation of ABCG2 was induced by 5-aza, which enhanced the ABCG2 expression level and influenced the cell proliferation similar to treatment with the anticancer agents. Our data suggest that the ABCG2 expression level regulated by methylation is related to anticancer drug sensitivity. Based on these results, it can be applied to predict the anticancer drug response.

Validation of Prediction Models for Mismatch Repair Gene Mutations in Koreans

PURPOSE

Lynch syndrome, the commonest hereditary colorectal cancer syndrome, is caused by germline mutations in mismatch repair (MMR) genes. Three recently developed prediction models for MMR gene mutations based on family history and clinical features (MMRPredict, PREMM(1,2,6), and MMRPro) have been validated only in Western countries. In this study, we propose validating these prediction models in the Korean population.

MATERIALS AND METHODS

We collected MMR gene analysis data from 188 individuals in the Korean Hereditary Tumor Registry. The probability of gene mutation was calculated using three prediction models, and the overall diagnostic value of each model compared using receiver operator characteristic (ROC) curves and area under the ROC curve (AUC). Quantitative test characteristics were calculated at sensitivities of 90%, 95%, and 98%.

RESULTS

Of the individuals analyzed, 101 satisfied Amsterdam criteria II, and 87 were suspected hereditary nonpolyposis colorectal cancer. MMR mutations were identified in 62 of the 188 subjects (33.0%). All three prediction models showed a poor predictive value of AUC (MMRPredict, 0.683; PREMM(1,2,6), 0.709; MMRPro, 0.590). Within the range of acceptable sensitivity (> 90%), PREMM(1,2,6) demonstrated higher specificity than the other models.

CONCLUSION

In the Korean population, overall predictive values of the three models (MMRPredict, PREMM(1,2,6), MMRPro) for MMR gene mutations are poor, compared with their performance in Western populations. A new prediction model is therefore required for the Korean population to detect MMR mutation carriers, reflecting ethnic differences in genotype-phenotype associations.

Clinicopathological Features and Type of Surgery for Lynch Syndrome: Changes during the Past Two Decades

Purpose

The Korean Hereditary Tumor Registry, the first and one of the largest registries of hereditary tumors in Korea, has registered about 500 families with hereditary cancer syndromes. This study evaluates the temporal changes in clinicopathologic features and surgical patterns of Lynch syndrome (LS) patients.

Materials and Methods

Data on 182 unrelated LS patients were collected retrospectively. The patients were divided into the period 1 group (registered in 1990-2004) and 2 (registered in 2005-2014). The clinical characteristics of the two groups were compared to identify changes over time.

Results

The period 1 group included 76 patients; the period 2 group, 106 patients. The mean ages at diagnosis were 45.1 years (range, 13 to 85 years) for group 1 and 49.7 years (range, 20 to 84 years) for group 2 (p=0.015). The TNM stage at diagnosis did not differ significantly—period 1 group: stage 0-I (n=18, 23.7%), II (n=37, 48.7%), III (n=19, 25.0%), and IV (n=2, 2.6%); period 2 group: stage 0-I (n=30, 28.3%), II (n=35, 33.0%), III (n=37, 34.9%), and IV (n=4, 3.8%). Extended resection was more frequently performed (55/76, 72.4%) in the period 1 group than period 2 (49/106, 46.2%) (p=0.001).

Conclusion

Colorectal cancer in patients with LS registered at the Korean Hereditary Tumor Registry is still diagnosed at an advanced stage, more than two decades after registry’s establishment. Segmental resection was more frequently performed in the past decade. A prompt nationwide effort to raise public awareness of hereditary colorectal cancer and to support hereditary cancer registries is required in Korea.

Interleukin-7 receptor contributes to increase of wound-healing migration as well as Invasion in the prostate cancer (TUM3P.1049)

IL-7Rα plays a critical role in the development and maintenance of immune cells but no studies suggest a verification of a key factor of bone metastasis. To investigate the role of IL-7Rα on bone metastases from prostate cancer, we evaluate the expression of IL-7Rα, wound healing migration, invasion, and zymography on the prostate cancer cells after IL-7 treatment. As results, the expression of IL-7Rα in PC-3 cells was higher than in other metastatic cell lines. Not only wound-healing but also invasion was increased after IL-7 treatment at the PC-3 cells. And, MMP2, MMP9 was also increased in PC-3 cells upon IL-7 stimulation. Moreover, the invasiveness of cells overexpressing IL-7Rα (PC-3IL-7Rα OE) was significantly increased compared to control cells. Furthermore, in order to elucidate the role of IL-7Rα in bone metastasis, PC-3IL-7Rα OE cells were administered into NSG mouse by intra-cardiac injection. Metastasis into the bone was markedly increased when PC-3IL-7Rα OE were injected compared with control vector expressed PC-3 cells. In conclusion, migration and invasion were increase in PC-3 cells after IL-7 treatment. Metastasis into bone was enhanced by PC-3IL-7Rα OE, suggesting IL-7Rα might be involved in migration as well as invasion in the bone metastatic prostate cancer. Acknowledgement: This research was supported by National Research Foundation of Korea (2014M3A7B4052194 for H Kim and 2014R1A6A3A01058743 for J Kim)

Abstract 780: Metformin induces apoptotic cell death and inhibits CD133+ cancer stem cells in 5-Fu-resistant colorectal cancer cells

Colorectal cancer (CRC) is the third most common cancer and estimated cancer related death is high in worldwide. 5-Fluorouracil (5-Fu) is common used chemotherapeutic agent for colorectal cancer. Nevertheless the use frequency, the resistance to 5-Fu is still a critical problem. To improvement of therapeutic effects of 5-Fu, there are the new chemotherapeutic strategies like FOLFOX and FORFIRI, combination treatment 5-Fu with oxaliplatin or irinotecan. However, it is arguable that the side effects and efficiency of these strategies.

Metformin is widely used therapeutic agent for type II diabetics, obesity, and polycystic ovarian syndrome with limited side effects. Recently, there are some evidence that metformin has anticancer effects for some types of cancers e.g. breast, pancreases, prostate, and colon. Recently, correlation of metformin and cancer stem cell population was proved.

Here, we examined that metformin effects on parental colorectal cancer cells and their 5-Fu-resistant colorectal cancer cells. Metformin has the anticancer effects in parental cells and their 5-Fu-resistant cells in both cell lines. As treated with metformin, wound healing ability is decreased in both cell lines. Cell proliferation was 41.7% decreased in parental cells and 30.6% in 5-Fu-resistant cells. Also, expression of PARP and caspase-3 were induced by metformin dose dependent manner in both cell lines. It is suggested that metformin induces inhibition of cell proliferation and increased apoptosis. In addition, metformin treatment affects cell cycle; subG1 stage was increased to 1.7 fold and G2/M stage was increased to 1.6 fold in both cell lines. It means that metformin induces cell death and leads cell cycle arrest. However, there are no significant synergistic effect in cell proliferation, apoptosis, and cell cycle change with combination treatment of 5-Fu and metformin. CD133+ cancer stem cell population was decreased in 20 to 40 % as treated with 5-Fu and low dose of metformin to parental cells. On the other hand, CD133+ population in 5-Fu-resistant cells was affected in only low dose of metformin not 5-Fu.

In sum, metformin has anticancer effects via inhibition of cell proliferation, cell cycle changes and metformin decreases CD133+ cancer stem cell population. Further studies will be necessary to verify the mechanisms that metformin decreases CD133+ cancer stem cell population in colorectal cancer cell lines.

Citation Format: Sunghee Kim, Ja-Lok Ku. Metformin induces apoptotic cell death and inhibits CD133+ cancer stem cells in 5-Fu-resistant colorectal cancer cells. [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 780. doi:10.1158/1538-7445.AM2014-780

Abstract 2783: Variability of HER2 expression between in vitro and in vivo models within gastric cancer cell lines

In the process of developing individualized cancer therapeutics, tumor derived cell line based preclinical (in vitro and in vivo) methods have been widely used. Patient derived genome analysis revealed significant cancer biomarkers for targeted drug development. Classic cancer biomarker, HER2, overexpression was discovered as a cancer biomarker and as a druggable target in breast cancer, which lead to the development of Trastuzumab. HER2 is overexpressed in 10-25% of gastric cancer, and treatment with Trastuzumab showed positive yet limited activity in advanced gastric cancer treatment in the ToGA study. These results present HER2 as an attractive target for gastric cancer. However, Gillet and colleagues reported the challenges in the use of in vitro and in vivo studies for drug validation and development. They reported variance in gene expression patterns between the in vitro and in vivo context within a single cancer cell line. In our study using gastric cancer derived cell lines, we observed differences in HER2 expression between in vitro and in vivo xenograft model. Also, we show the potential promising in vivo xenograft model in the development of HER2 targeting agents for gastric cancer.

Eleven out of 25 gastric cancer cell lines showed HER2 expression, which was demonstrated using the IHC assay on a cell microarray. Sixteen out of 25 cell lines successfully produced xenograft models. Gastric cancer cell lines (SNU-5, SNU-16, SNU-638, SNU-1967, MKN-1, MKN-28, and NUGC-3) that had no HER2 expression when cultured in vitro showed HER2 expression in vivo. Two cell lines (NCC-19 and NCI-N87) that had HER2 expression in vitro showed a decrease in HER2 expression in vivo. Three cell lines (SNU-484, SNU-668, and SNU-719) showed various levels of increase in HER2 expression. Two cell lines showed minor to no changes in HER2 expression. NUGC-4 had consistent significant HER2 expression levels in both assays, while MKN-45 had consistent insignificant to no HER2 expression. Our study demonstrates inconsistency in HER2 gene expression between in vitro and in vivo cancer cell line models for the first time in gastric cancer.

Citation Format: Youme Gim, Hee Seo Park, Hae Rim Jung, Hae Ryung Chang, Seungyoon Nam, Yong Doo Choi, Ja-Lok Ku, Yon Hui Kim. Variability of HER2 expression between in vitro and in vivo models within gastric cancer cell lines. [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 2783. doi:10.1158/1538-7445.AM2014-2783

A long non-coding RNA snaR contributes to 5-fluorouracil resistance in human colon cancer cells

Several types of genetic and epigenetic regulation have been implicated in the development of drug resistance, one significant challenge for cancer therapy. Although changes in the expression of non-coding RNA are also responsible for drug resistance, the specific identities and roles of them remain to be elucidated. Long non-coding RNAs (lncRNAs) are a type of ncRNA (> 200 nt) that influence the regulation of gene expression in various ways. In this study, we aimed to identify differentially expressed lncRNAs in 5-fluorouracil-resistant colon cancer cells. Using two pairs of 5-FU-resistant cells derived from the human colon cancer cell lines SNU-C4 and SNU-C5, we analyzed the expression of 90 lncRNAs by qPCR-based profiling and found that 19 and 23 lncRNAs were differentially expressed in SNU-C4R and SNU-C5R cells, respectively. We confirmed that snaR and BACE1AS were downregulated in resistant cells. To further investigate the effects of snaR on cell growth, cell viability and cell cycle were analyzed after transfection of siRNAs targeting snaR. Down-regulation of snaR decreased cell death after 5-FU treatment, which indicates that snaR loss decreases in vitro sensitivity to 5-FU. Our results provide an important insight into the involvement of lncRNAs in 5-FU resistance in colon cancer cells.