Cyclin A2 regulates erythrocyte morphology and numbers

Cyclin A2 is an essential gene for development and in haematopoietic stem cells and therefore its functions in definitive erythropoiesis have not been investigated. We have ablated cyclin A2 in committed erythroid progenitors in vivo using erythropoietin receptor promoter-driven Cre, which revealed its critical role in regulating erythrocyte morphology and numbers. Erythroid-specific cyclin A2 knockout mice are viable but displayed increased mean erythrocyte volume and reduced erythrocyte counts, as well as increased frequency of erythrocytes containing Howell-Jolly bodies. Erythroblasts lacking cyclin A2 displayed defective enucleation, resulting in reduced production of enucleated erythrocytes and increased frequencies of erythrocytes containing nuclear remnants. Deletion of the Cdk inhibitor p27^Kip1 but not Cdk2, ameliorated the erythroid defects resulting from deficiency of cyclin A2, confirming the critical role of cyclin A2/Cdk activity in erythroid development. Loss of cyclin A2 in bone marrow cells in semisolid culture prevented the formation of BFU-E but not CFU-E colonies, uncovering its essential role in BFU-E function. Our data unveils the critical functions of cyclin A2 in regulating mammalian erythropoiesis.

Direct Induction and Functional Maturation of Forebrain GABAergic Neurons from Human Pluripotent Stem Cells

Gamma-aminobutyric acid (GABA)-releasing interneurons play an important modulatory role in the cortex and have been implicated in multiple neurological disorders. Patient-derived interneurons could provide a foundation for studying the pathogenesis of these diseases as well as for identifying potential therapeutic targets. Here, we identified a set of genetic factors that could robustly induce human pluripotent stem cells (hPSCs) into GABAergic neurons (iGNs) with high efficiency. We demonstrated that the human iGNs express neurochemical markers and exhibit mature electrophysiological properties within 6-8 weeks. Furthermore, in vitro, iGNs could form functional synapses with other iGNs or with human-induced glutamatergic neurons (iENs). Upon transplantation into immunodeficient mice, human iGNs underwent synaptic maturation and integration into host neural circuits. Taken together, our rapid and highly efficient single-step protocol to generate iGNs may be useful to both mechanistic and translational studies of human interneurons.

CD275-Independent IL-17-Producing T Follicular Helper-like Cells in Lymphopenic Autoimmune-Prone Mice

T cells undergo homeostatic expansion and acquire an activated phenotype in lymphopenic microenvironments. Restoration of normal lymphocyte numbers typically re-establishes normal homeostasis, and proinflammatory cytokine production returns to baseline. Mice deficient in guanine nucleotide exchange factor RasGRP1 exhibit dysregulated homeostatic expansion, which manifests as lymphoproliferative disease with autoantibody production. Our previous work revealed that autoreactive B cells lacking RasGRP1 break tolerance early during development, as well as during germinal center responses, suggesting that T cell-independent and T cell-dependent mechanisms are responsible. Examination of whether a particular T cell subset is involved in the breach of B cell tolerance revealed increased Th17 cells in Rasgrp1-deficient mice relative to control mice. Rasgrp1-deficient mice lacking IL-17R had fewer germinal centers, and germinal centers that formed contained fewer autoreactive B cells, suggesting that IL-17 signaling is required for a break in B cell tolerance in germinal centers. Interestingly, a fraction of Th17 cells from Rasgrp1-deficient mice were CXCR5(+) and upregulated levels of CD278 coordinate with their appearance in germinal centers, all attributes of T follicular helper cells (Tfh17). To determine whether CD278-CD275 interactions were required for the development of Tfh17 cells and for autoantibody, Rasgrp1-deficient mice were crossed with CD275-deficient mice. Surprisingly, mice deficient in RasGRP1 and CD275 formed Tfh17 cells and germinal centers and produced similar titers of autoantibodies as mice deficient in only RasGRP1. Therefore, these studies suggest that requirements for Tfh cell development change in lymphopenia-associated autoimmune settings.

Abstract P5-02-06: Predicting the response of molecular targeting agents in triple-negative breast cancer cell lines by kinase activities

Introduction

Mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)-AKT pathways are two major hyper-activated cascades in triple-negative breast cancer (TNBC) that critically regulate cancer progression by enhancing cell survival, proliferation, metastasis, EMT, cancer stem cell regulate, and transformation. While many therapeutic agents targeting kinases in these pathways are being developed, the development of predictor of response for such agents are critical to successfully translate them into the clinic. Genomic analysis (amplification, deletion of mutation) is one of the prediction methods. However, these technologies do not always reflect the intrinsic functionalities/activities of the kinase molecules. Therefore, we hypothesized that kinase activity predicts the response to the targeted therapy in TNBC.

Materials and methods

Seventeen TNBC cell lines were used in this study. To analyze cell growth inhibition, cells were incubated for 72 h with various concentrations of trametinib or wortmannin, then processed for sulforhodamine B (SRB) staining assay. To measure MEK or PI3K enzymatic activity, TNBC cell lines were lysed and immunoprecipitated with magnetic beads conjugated with MEK antibody or with PI3K p110α antibody. Kinase reaction buffer including respective substrate and ATP was added to the immunoprecipitates and incubated for 120 minutes at 37 °C. Resultant ADP was quantified by HPLC and determined MEK and PI3K activities. Protein mass of MEK, PI3K, phospho-MEK and phospho-PI3K were determined by Western Blot analysis. Total protein amount was measured by A280. Lactate dehydrogenase (LDH) activity was measured by N-assay L LDH Nittobo. Total protein and LDH were used to normalize MEK and PI3K activities for the further analysis.

Results

Seventeen TNBC cell lines were classified into 4 groups depending on pattern of inhibition to two inhibitors as follows; Wortmannin (PI3K inhibitor) sensitive group (W, 2/17), Trametinib (MEK inhibitor) sensitive group (T, 2/17), Both sensitive group (S, 5/17) and Resistant group (R, 8/17). We found that ratio of PI3K activity and MEK activity showed good agreement to the cell classification (PPV [Wortmannin]: 67 %, PPV [Trametinib]: 33 %, NPV: = 100 %). The other parameters; enzymatic activity of MEK or PI3K, protein mass of MEK, PI3K, phospho-MEK, or phospho-PI3K, ratios of the protein mass, and the phospho-protein did not show statistically significant agreement to the classification. Mutational status and enzymatic activities or cell classification had no correlation. Additionally, MEK activity correlated to downstream phospho-ERK expression level (R = 0.7309).

Conclusion

Our results show that relative activity of two relevant kinases in the signaling cascade could predict the cell lines that will not respond to molecular targeting agents against corresponding cascades. Our concept should be warranted in the clinical study with statistically sufficient number of patients.

Citation Format: Sato N, Wakabayashi M, Lee J, Lim B, Ueno NT, Ishihara H. Predicting the response of molecular targeting agents in triple-negative breast cancer cell lines by kinase activities. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-02-06.

Abstract P1-14-07: Association between quantitative values of estrogen receptor expression level and pathological complete response in human epidermal growth factor 2-negative breast cancer: Should the clinical definition of triple-negative breast cancer be redefined?

Background: The American Society of Clinical Oncology/College of American Pathologists recommended that the cut-off for negative status of estrogen receptor (ER) should be <1% positively staining cells, although a 10% cut-off has often been used clinically. Prior studies reported that patients with ER ranging from 1% to 9% showed survival outcomes and molecular features similar to those of patients with ER positivity of <1%; however, those studies did not take into account patients' human epidermal growth factor 2 (HER2) status. This means we have yet to clarify the exact clinical definition of triple-negative breast cancer (TNBC) on the basis of response to preoperative chemotherapy. Previous studies reported that hormone receptor–positive tumors were less sensitive to systemic chemotherapies. On the basis of these facts, we hypothesized that in patients with HER2-negative breast cancer ER expression level as a continuous variable has an inverse linear association with pathological complete response (pCR) rate. Our primary objective was to determine whether a quantitative value of ER between 0% and 10% is predictive of pCR rate in HER2-negative patients treated with neoadjuvant chemotherapy. Secondary objective was to find the ideal cut-off value of ER expression.

Methods: We included newly diagnosed stage I-III HER2-negative breast cancer patients with available ER (0%≤ER<10%) who were treated with neoadjuvant systemic chemotherapy. ER status was determined by immunohistochemical (IHC) staining; HER2 status was determined by IHC and/or FISH. We used univariate and multivariate logistic regression models to determine the association between baseline variables and pCR. A backward stepwise method was used to select the covariates for the multivariate analysis. Recursive partitioning and regression tree method were used to identify the potential significant cut-off of ER.

Results: The analysis included 1155 patients with newly diagnosed HER2-negative invasive breast cancer. The univariate logistic regression analysis showed that ER as a continuous variable was not a statistically significant factor for predicting pCR (ER: OR=0.98, 95%CI: 0.9-1.07, P=0.68). In the multivariate analysis, ER status again was not a significant factor for predicting pCR (OR=0.97, 95%CI 0.9-1.06, P=0.55). ER as a categorical variable, there was no significant difference of the pCR rate between 0<ER<1 and 1≤ER<10 groups (OR=1.27, 95%CI: 0.62-2.62, P=0.52). Among ER> 0 (n=229), the recommended cut-off value of ER was 5.5. However, the odds ratio of pCR rate divided by this value of 5.5 was not significant (ER≤5 vs ER>5; OR 1.94 95%CI 0.54-6.95 P=0.31).

Conclusion: Evaluating ER (<10%) as a continuous variable showed no association with pCR rate, and no cut-off of ER was identified with which to stratify patients into groups more or less likely to achieve pCR. A potential meaningful cut-off ER value might exist between 10% and 100% in HER2-negative patients. We will explore whether a meaningful cut-off ER value exists that will change the pCR rate and possibly lead to redefining the clinical definition of TNBC.

Citation Format: Fujii T, Kogawa T, Dong W, Moulder S, Litton JK, Tripathy D, Lim B, Shen Y, Ueno NT. Association between quantitative values of estrogen receptor expression level and pathological complete response in human epidermal growth factor 2-negative breast cancer: Should the clinical definition of triple-negative breast cancer be redefined?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-07.

Abstract P3-07-58: CD44v as a potential predictive biomarker for pathologic complete response in primary HER2+ breast cancer: Utility of adaptive response biopsy in preoperative therapy

Background: Preoperative dual anti-HER2 therapy with lapatinib and trastuzumab in combination with conventional chemotherapy demonstrates a higher pathologic complete response rate (pCR) than trastuzumab with chemotherapy in patients with HER2+ breast cancer. Preoperative chemotherapy has been reported to increase the fraction of cancer stem-like cells (CSCs) in breast cancer, but this effect has not been well validated in clinical setting. Cancer cells with the epithelial-mesenchymal transition (EMT) phenotype also exhibit stem cell–like properties with drug resistance. Our goal was to determine the quantitative values of various biomarkers in baseline and adaptive response biopsy specimens and in subsequent surgical specimens to predict pCR in patients treated with dual anti-HER2 therapy as demonstrated by reduction of CSCs, phosphorylated receptors and signaling kinases, and circulating tumor cells (CTC) with the EMT phenotype. Methods: Eighteen patients with operable primary HER2+ invasive breast cancer (≥T2 excluding inflammatory breast cancer, any N) were eligible. Patients received lapatinib (1000 mg PO daily) + trastuzumab (4 mg/kg at loading, then 2 mg/kg IV weekly) for the first 6 weeks, then lapatinib (750 mg daily) + trastuzumab (2 mg/kg IV weekly) + paclitaxel (80 mg/m2 IV weekly) for 12 weeks, followed by surgery (ClinicalTrials.gov Identifier: NCT01688609). Tumor and blood specimens were collected before (baseline), after the 6 weeks of dual anti-HER2 therapy (adaptive response biopsy), and at 18 weeks, after 12 weeks of dual anti-HER2 therapy + paclitaxel (surgical specimens). We measured CSC biomarkers CD44 variant (CD44v) and aldehyde dehydrogenase-1 in tumor tissues, EMT markers in CTCs (TWIST1, SNAIL1, SLUG, ZEB1, and FOXC2) in blood samples by quantitative RT-PCR, and the ratios of phosphorylated EGFR (pEGFR)/EGFR, pHER2/HER2, pERK/ERK, and pAkt/Akt in tumor tissues. All tissue and CTC biomarker levels at all three time points were evaluated for their association with response via Fisher's exact test, McNemar's test, and Wilcoxon rank sum test according to the variables. Results: Eight of 18 patients (44.4%) achieved pCR after dual anti-HER2 therapy + concurrent paclitaxel. All patients who achieved pCR showed reduction or disappearance of CD44v+ cells over the treatment course. Five of the 10 non-pCR patients showed consistent CD44v expression or enrichment after dual anti-HER2 therapy in both the adaptive response biopsy and the surgical specimens. None of the eight pCR patients had detectable CD44v in the 7-week adaptive response biopsy specimen (Fisher exact test, two-tailed, P = 0.0359). None of the other markers significantly predicted pCR. Conclusion: Persistent expression or enrichment of CD44v was suggested to be predictive for non-pCR in breast cancer patients treated with preoperative dual anti-HER2 therapy plus concurrent cytotoxic chemotherapy. A single evaluation of biomarkers before therapy is insufficient for prediction of clinical response. Application of the adaptive response biopsy during the course of preoperative therapy might play a significant role in the success of therapeutic strategies that target CSCs.

Citation Format: Yamauchi T, Imamura CK, Yamauchi H, Jinno H, Takahashi M, Kitagawa Y, Nakamura S, Lim B, Krishnamurthy S, Reuben JM, Liu D, Tripathy D, Zujewski JA, Chen H, Takebe N, Saya H, Ueno NT. CD44v as a potential predictive biomarker for pathologic complete response in primary HER2+ breast cancer: Utility of adaptive response biopsy in preoperative therapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-58.

Abstract P4-14-22: A single-center, open-label phase 1b study of entinostat, and lapatinib alone, and in combination with and trastuzumab in patients with HER2+ metastatic breast cancer after progression on trastuzumab

Background: Our in vitro and in vivo preclinical data showed that entinostat enhances the efficacy of lapatinib in HER2 positive (HER2+) breast cancer cells via FOXO3-mediated Bim1 expression, which resulted in enhanced apoptosis in HER2 targeted therapy (lapatinib and trastuzumab)-resistant breast cancer (IBC and non-IBC) cells [Lee et al.]. Based on these findings, we conducted a phase 1b trial of entinostat to determine the maximal tolerated dose (MTD) in combination with lapatinib alone and in combination with lapatinib and trastuzumab for metastatic HER2+ breast cancer patients (pts), who progressed on trastuzumab.

Method: This was a single-center, open-label phase 1b study to evaluate the dose limiting toxicity (DLT) and determine MTD. 3+3 dose escalation schedule was used for Cohorts 1 and 2. Pts received lapatinib and entinostat (Cohort 1) or entinostat, lapatinib, and trastuzumab (Cohort 2). Initial dose of lapatinib 1250mg in Cohort 1 and 1000mg for Cohort 2 to match standard dose in combination with trastuzumab dose. In Cohort 1, entinostat was given PO on day 1 and 15 every 28 days cycle at dose levels 10 mg (level 0), 12 mg (level 1), or 15 mg (level 2). The dose levels for Cohort 2 were 12 mg (co-level 0) or 15 mg (co-level 1) on day 1 and 15 every 28 days cycle. While lapatinib and entinostat were given 28 days cycle due to entinostat dosing, the dosing of trastuzumab followed approved schedule every 21 days starting at 8mg/kg loading followed by 6mg/kg q 3 wks in Cohort 2 and 3. After the MTD of entinostat in cohort 2 was determined at 12mg, an expansion cohort of 10 pts (cohort 3) was conducted.

Results: Median age was 52 (26-69 yrs). Median number of prior trastuzumab-based regimens was 2 (1-6), 8 pts had lapatinib containing treatment prior to the trial, including 5 pts who had clinical benefit. 16 had ER+ and 13 ER negative, and 9 had IBC. Clinical efficacy and toxicity of treatment is summarized in table 1. Out of 14 pts who had clinical benefit (CR, PR, SD), 6 had IBC. Three pts are still on therapy (1CR, 1PR, 1SD).

Table 1. Clinical Efficacy, Toxicity of combination Receptor StatusResponseGrade 3 toxicityGrade 4 toxicityCohort 1HER2+/ER- (N=8) HER2+/ER+ (N=7)CR (N=1; 8M), SD (N=4;1,2,4M)Lapatinib dose reduction: 3 pts Rash (2) Abdominal pain + dyspnea (1)Entinostat dose reduction: 2pts Neutropenia (1 at 12mg, 1 at 15mg)Cohort 2/3HER2+/ER- (N=8) HER2+/ER+ (N=6)CR (N=2; 3,6M), PR (N=2;4,5M) SD (N=5;1,2,4,6M)Lapatinib dose reduction: 2 pts Diarrhea (N=1 at 12mg N=1 at 10mg) Entinostat dose reduction: 5 pts Neutropenia (N=2 at 12 mg) Leukopenia (N=1 at 12mg) Anemia (N=1 at 12mg)Entinostat dose reduction: 2pts Hypokalemia (N=1 at 12mg) Thrombocytopenia (N=1 at 15mg)CR: complete response, PR: partial response, SD: stable disease, N=number of pts, M=months

Conclusion: MTD was reached at 12mg q 2wkly entinostat, lapatinib 1000 mg daily and trastuzumab 8 mg/kg followed by 6mg/kg q 3 wks. This combination was safe and had promising clinical efficacy in patients with trastuzumab-resistant metastatic HER2+ breast cancer including IBC, warranting further study.

Citation Format: Lim B, Jackson S, Alvarez RH, Ibrahim NK, Willey JS, Murthy RK, Booser DJ, Giordano SH, Barcenas CH, Brewster A, Walters RS, Brown PH, Tripathy D, Valero V, Ueno NT. A single-center, open-label phase 1b study of entinostat, and lapatinib alone, and in combination with and trastuzumab in patients with HER2+ metastatic breast cancer after progression on trastuzumab. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-22.

Abstract B2-54: Intratumor heterogeneity in never-smoker Asian EGFR mutant lung adenocarcinoma

Lung cancer has the highest cancer associated mortality rate in many countries across the world. In contrast to western populations, approximately half of lung adenocarcinoma cases in Singapore harbour activating epidermal growth factor receptor (EGFR) mutations, with preponderance for never smokers and female gender. Although EGFR tyrosine kinase inhibitors (TKIs) confer high response rates of up to 70%, drug resistance invariably ensues - most commonly through the “acquisition” of EGFR T790M mutation. While the extent and pattern of intratumoral heterogeneity (ITH) in non-small cell lung cancer (NSCLC) were recently described, these studies examined histologically and molecularly diverse cohort of patients, majority being current or ex-smokers. Here we report ITH in eight never-smoker EGFR mutant lung adenocarcinoma cases of Asian ethnicity.

All eight patients had no prior treatment history and harboured an activating EGFR mutation (5 L858R , 2 exon 19 deletion, 1 exon 20 insertion). They underwent lobectomy for Stage IA, IB NSCLC. Tumors were harvested using a systematic sectoring protocol according to standard operation procedures, with tissue banked for exome sequencing, RNA-sequencing and SNP array. A total of 46 tumor sectors (at least 4 regions from each of the 8 tumors) were subject to whole exome sequencing, with matched normal samples.

With an average sequencing depth of 100x, we identified 860 somatic exonic SNVs (601 being non-synonymous) and 49 indels across all samples. The median number of SNVs per patient was 112 and per sector was 49. Notably, activating EGFR mutations were identified across all tumor sectors of all but two patients (for whom it was identified in 3 of 5 and 5 of 7 sectors respectively). In addition, we did not identify the EGFR T790M mutation in any of the sequenced tumor sectors, suggesting that, this resistance mutation is not present at detectable frequencies even as a branch or subclonal event in a treatment naïve scenario. Of 20 genes that were significantly mutated across 46 individual tumor sectors, only two overlapped with published recurrently mutated genes in NSCLC.

In conclusion, we show that activating EGFR mutations are ubiquitous truncal events in 6 of 8 Asian never-smoker lung adenocarcinoma – consistent with its role as a therapeutically tractable driver gene. The T790M mutation commonly associated with TKI resistance was not detected as a subclonal event in treatment naïve patients. Further, our study reveals the unique mutation spectra of Asian EGFR mutant lung adenocarcinoma, highlighting the value of multi-region sequencing in characterising the genomic architecture of defined molecular subsets of NSCLC from different ethnic backgrounds.

Citation Format: Rahul Nahar, Weiwei Zhai, Angela Takano, Alexis Jiaying Khng, Xingliang Liu, Chong Hee Lim, Audrey S.M. Teo, Cheryl Xueli Chan, Apoorva Gogna, Kiat-Hon Lim, Tina Koh, Huay Mei Poh, Yin Yeng Lee, Liang He Chen, Tong Zhang, Vidhya Gomathi Krishnan, N Gopalakrishna Iyer, Pauline Ng, Wan Teck Lim, Bing Lim, Eng-Huat Tan, Daniel S.W. Tan, Axel M. Hillmer. Intratumor heterogeneity in never-smoker Asian EGFR mutant lung adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Computational and Systems Biology of Cancer; Feb 8-11 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 2):Abstract nr B2-54.

Abstract A1-25: Intratumor heterogeneity in never-smoker Asian EGFR mutant lung adenocarcinoma

Lung cancer has the highest cancer associated mortality rate in many countries across the world. In contrast to western populations, approximately half of lung adenocarcinoma cases in Singapore harbour activating epidermal growth factor receptor (EGFR) mutations, with preponderance for never smokers and female gender. Although EGFR tyrosine kinase inhibitors (TKIs) confer high response rates of up to 70%, drug resistance invariably ensues - most commonly through the “acquisition” of EGFR T790M mutation. While the extent and pattern of intratumoral heterogeneity (ITH) in non-small cell lung cancer (NSCLC) were recently described, these studies examined histologically and molecularly diverse cohort of patients, majority being current or ex-smokers. Here we report ITH in eight never-smoker EGFR mutant lung adenocarcinoma cases of Asian ethnicity.

All eight patients had no prior treatment history and harboured an activating EGFR mutation (5 L858R, 2 exon 19 deletion, 1 exon 20 insertion). They underwent lobectomy for Stage IA, IB NSCLC. Tumors were harvested using a systematic sectoring protocol according to standard operation procedures, with tissue banked for exome sequencing, RNA-sequencing and SNP array. A total of 46 tumor sectors (at least 4 regions from each of the 8 tumors) were subject to whole exome sequencing, with matched normal samples.

With an average sequencing depth of 100x, we identified 860 somatic exonic SNVs (601 being non-synonymous) and 49 indels across all samples. The median number of SNVs per patient was 112 and per sector was 49. Notably, activating EGFR mutations were identified across all tumor sectors of all but two patients (for whom it was identified in 3 of 5 and 5 of 7 sectors respectively). In addition, we did not identify the EGFR T790M mutation in any of the sequenced tumor sectors, suggesting that, this resistance mutation is not present at detectable frequencies even as a branch or subclonal event in a treatment naïve scenario. Of 20 genes that were significantly mutated across 46 individual tumor sectors, only two overlapped with published recurrently mutated genes in NSCLC.

In conclusion, we show that activating EGFR mutations are ubiquitous truncal events in 6 of 8 Asian never-smoker lung adenocarcinoma – consistent with its role as a therapeutically tractable driver gene. The T790M mutation commonly associated with TKI resistance was not detected as a subclonal event in treatment naïve patients. Further, our study reveals the unique mutation spectra of Asian EGFR mutant lung adenocarcinoma, highlighting the value of multi-region sequencing in characterising the genomic architecture of defined molecular subsets of NSCLC from different ethnic backgrounds.

Citation Format: Rahul Nahar, Weiwei Zhai, Angela Takano, Alexis Jiaying Khng, Xingliang Liu, Chong Hee Lim, Audrey S.M. Teo, Cheryl Xueli Chan, Apoorva Gogna, Kiat-Hon Lim, Tina Koh, Huay Mei Poh, Yin Yeng Lee, Liang He Chen, Tong Zhang, Vidhya Gomathi Krishnan, N Gopalakrishna Iyer, Pauline Ng, Wan Teck Lim, Bing Lim, Eng-Huat Tan, Daniel S.W. Tan, Axel M. Hillmer. Intratumor heterogeneity in never-smoker Asian EGFR mutant lung adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Translation of the Cancer Genome; Feb 7-9, 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 1):Abstract nr A1-25.

Oocyte Factors Suppress Mitochondrial Polynucleotide Phosphorylase to Remodel the Metabolome and Enhance Reprogramming

Oocyte factors not only drive somatic cell nuclear transfer reprogramming but also augment the efficiency and quality of induced pluripotent stem cell (iPSC) reprogramming. Here, we show that the oocyte-enriched factors Tcl1 and Tcl1b1 significantly enhance reprogramming efficiency. Clonal analysis of pluripotency biomarkers further show that the Tcl1 oocyte factors improve the quality of reprogramming. Mechanistically, we find that the enhancement effect of Tcl1b1 depends on Akt, one of its putative targets. In contrast, Tcl1 suppresses the mitochondrial polynucleotide phosphorylase (PnPase) to promote reprogramming. Knockdown of PnPase rescues the inhibitory effect from Tcl1 knockdown during reprogramming, whereas PnPase overexpression abrogates the enhancement from Tcl1 overexpression. We further demonstrate that Tcl1 suppresses PnPase's mitochondrial localization to inhibit mitochondrial biogenesis and oxidation phosphorylation, thus remodeling the metabolome. Hence, we identified the Tcl1-PnPase pathway as a critical mitochondrial switch during reprogramming.

Non-invasive sensitive detection of KRAS and BRAF mutation in circulating tumor cells of colorectal cancer patients

Characterization of genetic alterations in tumor biopsies serves as useful biomarkers in prognosis and treatment management. Circulating tumor cells (CTCs) obtained non-invasively from peripheral blood could serve as a tumor proxy. Using a label-free CTC enrichment strategy that we have established, we aimed to develop sensitive assays for qualitative assessment of tumor genotype in patients. Blood consecutively obtained from 44 patients with local and advanced colorectal cancer and 18 healthy donors were enriched for CTCs using a size-based microsieve technology. To screen for CTC mutations, we established high-resolution melt (HRM) and allele-specific PCR (ASPCR) KRAS-codon 12/13- and BRAF-codon 600- specific assays, and compared the performance with pyrosequencing and Sanger sequencing. For each patient, the resulting CTC genotypes were compared with matched tumor and normal tissues. Both HRM and ASPCR could detect as low as 1.25% KRAS- or BRAF-mutant alleles. HRM detected 14/44 (31.8%) patients with KRAS mutation in CTCs and 5/44 (11.3%) patients having BRAF mutation in CTCs. ASPCR detected KRAS and BRAF mutations in CTCs of 10/44 (22.7%) and 1/44 (2.3%) patients respectively. There was an increased detection of mutation in blood using these two methods. Comparing tumor tissues and CTCs mutation status using HRM, we observed 84.1% concordance in KRAS genotype (p = 0.000129, Fishers' exact test; OR = 38.7, 95% CI = 4.05-369) and 90.9% (p = 0.174) concordance in BRAF genotype. Our results demonstrate that CTC enrichment, coupled with sensitive mutation detection methods, may allow rapid, sensitive and non-invasive assessment of tumor genotype.

Ex Uno Plures: Molecular Designs for Embryonic Pluripotency

Pluripotent cells in embryos are situated near the apex of the hierarchy of developmental potential. They are capable of generating all cell types of the mammalian body proper. Therefore, they are the exemplar of stem cells. In vivo, pluripotent cells exist transiently and become expended within a few days of their establishment. Yet, when explanted into artificial culture conditions, they can be indefinitely propagated in vitro as pluripotent stem cell lines. A host of transcription factors and regulatory genes are now known to underpin the pluripotent state. Nonetheless, how pluripotent cells are equipped with their vast multilineage differentiation potential remains elusive. Consensus holds that pluripotency transcription factors prevent differentiation by inhibiting the expression of differentiation genes. However, this does not explain the developmental potential of pluripotent cells. We have presented another emergent perspective, namely, that pluripotency factors function as lineage specifiers that enable pluripotent cells to differentiate into specific lineages, therefore endowing pluripotent cells with their multilineage potential. Here we provide a comprehensive overview of the developmental biology, transcription factors, and extrinsic signaling associated with pluripotent cells, and their accompanying subtypes, in vitro heterogeneity and chromatin states. Although much has been learned since the appreciation of mammalian pluripotency in the 1950s and the derivation of embryonic stem cell lines in 1981, we will specifically emphasize what currently remains unclear. However, the view that pluripotency factors capacitate differentiation, recently corroborated by experimental evidence, might perhaps address the long-standing question of how pluripotent cells are endowed with their multilineage differentiation potential.

Nurses compliance to hand hygiene practice and knowledge at Klang Valley hospital

BACKGROUND AND AIMS

Hand hygiene is the most important measure in the prevention of healthcare-associated infections (HCAI). Adherence to hand hygiene protocols in hospital by nurses enables in prevention and control the HCAI. The main aim of the present study was to assess nurses' compliance to hand hygiene practice and knowledge in a hospital.

MATERIALS AND METHODS

A descriptive cross-sectional study was conducted in the intensive care units of a hospital in Kuala Lumpur. A total of 84 registered nurses from the intensive care were recruited for this study. A self-administered questionnaire was deployed to measure knowledge and compliance about hand hygiene.

RESULTS

The findings showed the total mean and standard deviation of knowledge (60.65±4.213) and compliance (84.65±7.024) to be high among the respondents. There were no significant differences with the knowledge and compliance to hand hygiene with respondents' age groups with a p value >0.05. However, there were significant differences between respondents' years of service with the knowledge and compliance with p values <0.05. The results showed significant differences between respondents' with post basic course with compliance to hand hygiene with a p value <0.05 actual p value added (p = 0.001). There were no significant differences between the respondents' post basic course with knowledge to hand hygiene with p values >0.05 actual p value added (p=0.072).

CONCLUSION

Nurses compliance to hand hygiene practice and knowledge was good. Nurses' years of service have great implications on compliance to hand hygiene practice. The study opines that constant reinforcement and motivation are required by the hospital infection control team to impart hand hygiene practice.

Abstract 1654: Immune repertoire amongst subpopulations of tumor infiltrating lymphocytes (TILs) in colorectal cancer: Oligoclonality is predominantly observed in cytotoxic CD8+ TILs

Introduction: The immunophenotype and density of immune cell infiltrates in colorectal cancer (CRC) has consistently been shown to correlate with patient prognosis suggesting that the immune microenvironment plays an important role in regulating tumor progression. However, the immune repertoire of these tumor infiltrating lymphocytes has not been well characterized.

Methods: In this pilot study, we characterized the immue repertoire through TCR sequencing of T lymphocytes in the CRC tumor microenvironment and normal adjacent colonic mucosa. We collected fresh tumor and adjacent normal colonic mucosal tissue specimens from 2 patients who underwent surgery for CRC. A part of the tumor specimen was dissociated and sorted for collection of CD4+ and CD8+ T lymphocytes using FACSAria III cell sorter. 4 samples consisting of fresh frozen tumor, sorted CD4+ and CD8+ TILs and fresh frozen adjacent normal colonic mucosal tissue of each of the 2 patients were then sent for T-cell receptor β (TCRβ) complementarity-determining region 3 (CDR3) amplification and high-throughput next generation sequencing using the ImmunoSEQ platform at Adaptive Biotechnologies. The TCRβ CDR3 regions were then determined based on the definitions established by the ImMunoGeneTics Collaboration.

Results: The median total number of unique TCRβ CDR3 sequences identified in each of the 8 specimens evaluated was 5726 (range 475 to 54699), with an average of 78.3% of each specimen being productive sequences (range 75.1% to 81.9%). We next evaluated the diversity of T cell repertoire in terms of abundance and distribution of the T cell populations. There were more unique T cell clones present in the adjacent normal colonic mucosa (54699 and 24255) than in the tumor (7026 and 20887). Amongst the sorted TILs, there were less unique CD8+ T cell clones (561 and 475) compared to unique CD4+ T cell clones (2913 and 4426). There were fewer numbers of dominant clones making up 50% of total CDR3 reads in the CD8+ sorted TILs (15 and 29) compared to sorted CD4+ TILs (150 and 179), tumor tissue (390 and 668) and adjacent normal mucosa (1125 and 185).

Conclusion: Preliminary data from this pilot study suggests an oligoclonal population of cytotoxic T cells within the tumor microenvironment. We hypothesize that clonal expansion of these cytotoxic T cells were in response to specific tumor antigen stimulation. We have expanded the T cells and generated patient derived CRC cell lines. Further analysis of this population of expanded tumor infiltrating lymphocytes against their specific tumor cell lines are ongoing to evaluate T cell recognition and cytotoxic activity.

Citation Format: Si Lin Koo, Rachel Rui Xian Ten, Thin Zar Aung, Dennis Koh, Who Whong Wang, Wei Qiang Leow, Kiat Hon Lim, Suk Peng Chew, Ju Yuan, Bing Lim, Salvatore Albani, Iain Beehuat Tan. Immune repertoire amongst subpopulations of tumor infiltrating lymphocytes (TILs) in colorectal cancer: Oligoclonality is predominantly observed in cytotoxic CD8+ TILs. [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 1654. doi:10.1158/1538-7445.AM2014-1654

Abstract 1438: Targeting metabolic enzyme with locked nucleic acids in non-small cell lung cancer

Despite advances in our knowledge of genetics of cancer and some progress in cancer treatment over the last few decades, lung cancer remains the leading cause of cancer mortality worldwide. Recently cancer metabolomics have been widely applied into cancer research, including of cancer diagnosis and therapy. Our recent work has identified tumor initiating cells (TICs) derived from non-small cell lung cancer (NSCLC) patients and shown that metabolic enzyme glycine decarboxylase (GLDC) is critical for TICs in NSCLC. In the clinic, aberrant activation of GLDC correlates with poorer survival in lung cancer patients. Those findings provide potential diagnostic markers and/or therapeutic target for NSCLC. Locked nucleic acids (LNAs) are novel high-affinity DNA analogs that can be used as genotype-specific drugs. In this study we tested NSCLC patient-derived xenograft tumor growth inhibition by GLDC LNAs antisense oligonucleotides. These LNAs antisense oligonucleotides strongly reduce GLDC protein levels. The osmotic minipumps were filled with GLDC LNAs antisense oligonucleotides at 0.5,1 and 5 mg/kg/day dose and implanted dorsally into tumor-bearing NOD/SCID Il2rγ-/- mice. Tumor growth was inhibited at dosages from 1 mg/kg/day. LNAs antisense oligonucleotides appeared to be non-toxic at dosages of 5 mg/kg/day. Furthermore, we found significant changes of serum metabolomics in lung cancer patients compared to normal donors. Our data show that GLDC LNAs antisense oligonucleotides are potent genotype-specific drugs that can inhibit lung tumor growth in vivo.

Note: This abstract was not presented at the meeting.

Citation Format: Wen Cai Zhang, Bing Lim. Targeting metabolic enzyme with locked nucleic acids in non-small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1438. doi:10.1158/1538-7445.AM2014-1438

Divergent LIN28-mRNA associations result in translational suppression upon the initiation of differentiation

LIN28 function is fundamental to the activity and behavior of human embryonic stem cells (hESCs) and induced pluripotent stem cells. Its main roles in these cell types are the regulation of translational efficiency and let-7 miRNA maturation. However, LIN28-associated mRNA cargo shifting and resultant regulation of translational efficiency upon the initiation of differentiation remain unknown. An RNA-immunoprecipitation and microarray analysis protocol, eRIP, that has high specificity and sensitivity was developed to test endogenous LIN28-associated mRNA cargo shifting. A combined eRIP and polysome analysis of early stage differentiation of hESCs with two distinct differentiation cues revealed close similarities between the dynamics of LIN28 association and translational modulation of genes involved in the Wnt signaling, cell cycle, RNA metabolism and proteasomal pathways. Our data demonstrate that change in translational efficiency is a major contributor to early stages of differentiation of hESCs, in which LIN28 plays a central role. This implies that eRIP analysis of LIN28-associated RNA cargoes may be used for rapid functional quality control of pluripotent stem cells under manufacture for therapeutic applications.