Autophagy induction causes a synthetic lethal sensitization to ribonucleotide reductase inhibition in breast cancer cells

Macroautophagy can promote cellular survival or death depending on the cellular context and its extent. We hypothesized that autophagy induction would synergize with a therapeutic agent targeting the autophagic cargo. To test this hypothesis, we treated breast cancer MDA-MB-231 cells with tamoxifen (TMX), which induces autophagy through an estrogen receptor-independent pathway. Induction of autophagy reduced cellular levels of RRM2, a subunit of ribonucleotide reductase (RR), the rate limiting enzyme in the production of deoxyribonucleotide triphosphates (dNTPs). This autophagy inducer was combined with COH29, an inhibitor developed in our laboratory that targets RR through a novel mechanism. The combination therapy showed synergistic effects on cytotoxicity in vitro and in an in vivo xenograft model. This cytotoxicity was blocked by knockdown of the autophagy protein ATG5 or addition of chloroquine, an autophagy inhibitor. The combined therapy also induced dNTP depletion and massive genomic instability, leading us to hypothesize that combining autophagy induction with RR inhibition can lead to mitotic catastrophe in rapidly dividing cells. We propose that this TMX + COH29 combined therapy may have clinical benefit. Furthermore, autophagy induction may be a general mechanism for augmenting the effects of chemotherapeutic agents.

Integrin β3 and LKB1 are independently involved in the inhibition of proliferation by lovastatin in human intrahepatic cholangiocarcinoma

Human intrahepatic cholangiocarcinomas are one of the most difficult cancers to treat. In our study, Lovastatin, a 3-hydroxy-3-methylglutaryl-coenzyme-CoA (HMG-CoA) reductase inhibitor, demonstrated anticancer properties by inhibiting cancer cell proliferation, cell migration and cell adhesion. Lovastatin inhibited the expressions of transforming growth factor (TGF)-β1, cyclooxygenase (COX)-2, and intercellular adhesion molecule (ICAM)-1. Furthermore, lovastatin inhibited the expressions of integrin β1 and integrin β3 but not integrin αv or integrin β5. While Lovastatin's inhibitory effects on TGFβ1, COX2, and ICAM-1 expression were independently controlled by the tumor suppressor LKB1, integrin β3 expression was not affected. Lovastatin's inhibitory effect on cell adhesion was associated with the decreased expression of integrin β3 and cell surface heterodimer integrin αvβ3. Quantitative real time PCR, fluorescent microscopy, and cell migration assays all confirmed that Lovastatin inhibits integrin αvβ3 downstream signaling including FAK activation, and β-catenin, vimentin, ZO-1, and β-actin. Overall, Lovastatin reduced tumor cell proliferation and migration by modifying the expression of genes involved in cell adhesion and other critical cellular processes. Our study highlights novel anti-cancer properties of Lovastatin and supports further exploration of statins in the context of cholangiocarcinoma therapy.

Signature miRNAs in colorectal cancers were revealed using a bias reduction small RNA deep sequencing protocol

To explore the role of miRNAs in colorectal cancers (CRC), we have deep sequenced 48 pairs of frozen CRC samples, of which 44 pairs produced high quality sequencing data. By using a combined approach of our bias reduction small RNA (smRNA) deep sequencing protocol and Illumina small RNA TruSeq method for sample bar coding, we have obtained data from samples of relatively large size with bias reduced digital profile results. This novel approach allowed us to validate many previously published results using various techniques to profile miRNAs in CRC tissues or cell lines and to characterize ‘true’ miRNA signatures highly expressed in colon/rectum (CR) or CRC tissues. According to our results, miR-21, a miRNA that is up-regulated in CRC, and miR-143, a miRNA that is down-regulated in CRC, are the two miRNAs that dominated the miRNA population in CR tissues, and probably are also the most important miRNAs in CRCs. These two miRNAs, together with the other eight miRNAs, miR-148a, -194, -192, 200b, -200c, -10b, -26a, and -145, with descending expressing levels, constituted the top 10 highly expressed miRNAs in CR/CRC. Using TaqMan miRNA qPCR, we detected the relative expression of some of the CRC miRNAs in 10 CRC cell lines, validated their dysregulation under cancer condition, and provided possible explanation for their dysregulation, which could be caused by APC, KRAS, or TP53 mutations. We believe these results will provide a new direction in future miRNA-related CRC development studies, and application of miRNAs in CRC diagnosis/prognosis, and therapy.

Does aspirin use reduce the risk for cancer?

Recently, studies have reported that aspirin has chemopreventive properties. In this study, we used the Taiwan NHI database, which covers a population of 23 million (99.99%) Taiwanese from 2001 to 2011. This was a case-control study which identified 601,733 patients using ICD-9-CM codes who were diagnosed with cancer. Each case with 4 eligible controls was matched for age, sex, and index date and adjusted for confounding factors. The observed overall cancer risk (adjusted OR (AOR), 0.95; 95% CI 0.94 to 0.96) reduced with aspirin use, specifically, colorectal (AOR, 0.97; 95% CI 0.94 to 0.99) and digestive system (AOR, 0.96; 95% CI 0.94 to 0.98) cancers. Findings from the Asian population would contribute to the discussion on aspirin's safety profile.

Prognostic and therapeutic value of mitochondrial serine hydroxyl-methyltransferase 2 as a breast cancer biomarker

Mitochondrial serine hydroxylmethyltransferase 2 (SHMT2) is a key enzyme in the serine/glycine synthesis pathway. SHMT2 has been implicated as a critical component for tumor cell survival. The aim of the present study was to evaluate the prognostic value and efficiency of SHMT2 as a biomarker in patients with breast cancer. Individual and pooled survival analyses were performed on five independent breast cancer microarray datasets. Gene signatures enriched by SHMT2 were also analyzed in these datasets. SHMT2 protein expression was detected using immunohistochemistry (IHC) assay in 128 breast cancer cases. Gene set enrichment analysis revealed that SHMT2 was significantly associated with gene signatures of mitochondrial module, cancer invasion, metastasis and poor survival among breast cancer patients (p<0.05). The clinical relevance of SHMT2 was validated on IHC data. The mitochondrial localization of SHMT2 protein was visualized on IHC staining. Independent and pooled analysis confirmed that SHMT2 expression was associated with breast cancer tumor aggressiveness (TNM staging and Elson grade) in a dose-dependent manner (p<0.05). The prognostic performance of SHMT2 mRNA was comparable to other gene signatures and proved superior to TNM staging. Further analysis results indicated that SHMT2 had better prognostic value for estrogen receptor (ER)-negative breast cancer patients, compared to ER-positive patients. In cases involving stage IIb breast cancer, chemotherapy significantly extended survival time among patients with high SHMT2 expression. These results indicate that SHMT2 may be a valuable prognostic biomarker in ER-negative breast cancer cases. Furthermore, SHMT2 may be a potential target for breast cancer treatment and drug discovery.

Lowered circulating aspartate is a metabolic feature of human breast cancer

Distinct metabolic transformation is essential for cancer cells to sustain a high rate of proliferation and resist cell death signals. Such a metabolic transformation results in unique cellular metabolic phenotypes that are often reflected by distinct metabolite signatures in tumor tissues as well as circulating blood. Using a metabolomics platform, we find that breast cancer is associated with significantly (p = 6.27E-13) lowered plasma aspartate levels in a training group comprising 35 breast cancer patients and 35 controls. The result was validated with 103 plasma samples and 183 serum samples of two groups of primary breast cancer patients. Such a lowered aspartate level is specific to breast cancer as it has shown 0% sensitivity in serum from gastric (n = 114) and colorectal (n = 101) cancer patients. There was a significantly higher level of aspartate in breast cancer tissues (n = 20) than in adjacent non-tumor tissues, and in MCF-7 breast cancer cell line than in MCF-10A cell lines, suggesting that the depleted level of aspartate in blood of breast cancer patients is due to increased tumor aspartate utilization. Together, these findings suggest that lowed circulating aspartate is a key metabolic feature of human breast cancer.

Chemotherapy for advanced biliary tract carcinoma: A meta-analysis of randomized controlled trials

BACKGROUND

Although gemcitabine and platinum-based agents (GP) are currently regarded as the standard chemotherapy for advanced biliary tract cancer (BTC), the prognosis remains poor. Combinations with fluoropyrimidines and targeted therapy have demonstrated modest benefits. Therefore, we conducted a meta-analysis of randomized controlled trials to evaluate the efficacy of different chemotherapy regimens.

METHODS

The PubMed, EMBASE, Cochrane Library, Scopus, and ClinicalTrials.gov registries were searched for studies published until April 2016. A meta-analysis was conducted to calculate the pooled effect size by using random effects models. Treatment efficacies were measured using progression-free survival (PFS) and overall survival. The secondary outcomes included the objective response rate (ORR), 1-year survival rate, quality of life, disease control rate, and adverse events.

RESULTS

Fifteen trials that involved examining 1775 patients were reviewed. Patients who received epidermal growth factor receptor (EGFR)-targeted therapy in addition to standard GP chemotherapy exhibited a significantly higher median PFS (weighted mean difference = -1.49; 95% confidence interval -2.56 to -0.43), PFS (hazard ratio = 0.79; 95% confidence interval 0.63-0.99), and ORR (odd ratio = 0.56; 95% confidence interval 0.38-0.82). Combining GP with fluoropyrimidines or vascular EGFR inhibitors (VEGFR) did not improve patient outcomes.

CONCLUSION

Combining EGFR-targeted therapy with the current standard GP chemotherapy is a safe and viable option that may improve the median PFS, PFS, and ORR in patients with advanced BTC. Further research investigating the optimal dosage and drug type of EGFR inhibitors for specific BTC patient groups is warranted.

The Impact of dUTPase on Ribonucleotide Reductase-Induced Genome Instability in Cancer Cells

The appropriate supply of dNTPs is critical for cell growth and genome integrity. Here, we investigated the interrelationship between dUTP pyrophosphatase (dUTPase) and ribonucleotide reductase (RNR) in the regulation of genome stability. Our results demonstrate that reducing the expression of dUTPase increases genome stress in cancer. Analysis of clinical samples reveals a significant correlation between the combination of low dUTPase and high R2, a subunit of RNR, and a poor prognosis in colorectal and breast cancer patients. Furthermore, overexpression of R2 in non-tumorigenic cells progressively increases genome stress, promoting transformation. These cells display alterations in replication fork progression, elevated genomic uracil, and breaks at AT-rich common fragile sites. Consistently, overexpression of dUTPase abolishes R2-induced genome instability. Thus, the expression level of dUTPase determines the role of high R2 in driving genome instability in cancer cells.

Underexpression of LKB1 tumor suppressor is associated with enhanced Wnt signaling and malignant characteristics of human intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a rare and highly aggressive malignancy. In this study, we identified the presence of gene deletion and missense mutation leading to inactivation or underexpression of liver kinase B1 (LKB1) tumor suppressor and excluded the involvement of LKB1 gene hypermethylation in ICC tissues. Immunohistochemical analysis showed that LKB1 was underexpressed in a portion of 326 ICC tissues compared to their adjacent normal tissues. By statistical analysis underexpression of LKB1 in ICC tissues significantly correlated with poor survival and malignant disease characteristics in ICC patients. Moreover, we showed that knockdown of LKB1 significantly enhanced growth, migration, and invasion of three LKB1-competent ICC cell lines. Global transcriptional profiling analysis identified multiple malignancy-promoting genes, such as HIF-1α, CD24, Talin1, Vinculin, Wnt5, and signaling pathways including Hedgehog, Wnt/β-catenin, and cell adhesion as novel targets of LKB1 underexpression in ICC cells. Furthermore, knockdown of LKB1 gene expression dramatically enhanced Wnt/β-catenin signaling in ICC cells, while an inverse correlation between LKB1 and nuclear β-catenin was observed in ICC tissues. Our findings suggest a novel mechanism for ICC carcinogenesis in which LKB1 underexpression enhances multiple signaling pathways including Wnt/β-catenin to promote disease progression.

Pu-erh Tea Extract Attenuates Nicotine-Induced Foam Cell Formation in Primary Cultured Monocytes: An in Vitro Mechanistic Study

In this study, the mechanisms by which pu-erh tea extract (PETE) attenuates nicotine-induced foam cell formation were investigated. Monocytes were purified from healthy individuals using commercial antibodies coated with magnetic beads. We found that the nicotine-induced (1-10 μM) expression of oxidized low-density lipoprotein receptors (ox-LDLRs) and α9-nAchRs in monocytes was significantly attenuated by 24 h of PETE (10 μg/mL; ∗, p < 0.05) cotreatment. Nicotine (1 μM for 24 h) significantly induced the expression of the surface adhesion molecule ICAM-1 and the monocyte integrin adhesion molecule (CD11b) by human umbilical vein endothelial cells (HUVECs) and triggered monocytes to differentiate into macrophages via interactions with the endothelium. After treatment with nicotine (0.1-10 μM for 24 h), the HUVECs released chemotactic factors (IL-8) to attract monocytes into the tunica intima of the artery, and the monocytes then transformed into foam cells. We demonstrated that PETE treatment (>1 μg/mL for 24 h; ∗, p < 0.05) significantly attenuates nicotine-induced (1 μM) monocyte migration toward HUVECs and foam cell formation. This study suggests that tea components effectively attenuate the initial step (foam cell formation) of nicotine-induced atherosclerosis in circulating monocytes.

Elevated HMGA2 expression is associated with cancer aggressiveness and predicts poor outcome in breast cancer

High mobility group AT-hook 2 (HMGA2) is involved in a wide spectrum of biological processes and is upregulated in several tumors. Here, we collected 273 breast cancer (BC) specimens as a training set and 310 specimens as a validation set to examine the expression of HMGA2 by immunohistochemical staining. It was found that HMGA2 expression was significantly positively correlated with advanced tumor grade and poor survival. Subgroup analysis indicated that high level of HMGA2 was significantly correlated with poor prognosis, especially in the subgroups of stage II-III, low pathological grade and non-triple negative breast cancer cases. Gene set enrichment analysis (GSEA) demonstrated a significant positive correlation between HMGA2 level and the gene expression signature of metaplastic and mesenchymal phenotype. Importantly, we also observed that ectopic expression of HMGA2 promoted the migration and invasion of breast cancer cells, and protected cancer cells against genotoxic stress from agents stimulating P53 (Ser15) phosphorylation. As a conclusion, expression of HMGA2 might indicate more advanced malignancy of breast cancer. Thus we believe HMGA2 could serve as a biomarker of poor prognosis and a novel target in treating BC tumors.

The pan-PI3K inhibitor GDC-0941 activates canonical WNT signaling to confer resistance in TNBC cells: resistance reversal with WNT inhibitor

The pan-PI3K inhibitors are one treatment option for triple-negative breast cancer (TNBC). However, this treatment is ineffective for unknown reasons. Here, we report that aberrant expression of wingless-type MMTV integration site family (WNT) and activated WNT signals, which crosstalk with the PI3K-AKT-mTOR signaling pathway through GSK3β, plays the most critical role in resistance to pan-PI3K inhibitors in TNBC cells. GDC-0941 is a pan-PI3K inhibitor that activates the WNT/beta-catenin pathway in TNBC cells through stimulation of WNT secretion. GDC-0941-triggered WNT/beta-catenin pathway activation was observed in MDA-MB-231 and HCC1937 cells, which are TNBC cell lines showing aberrant WNT/beta-catenin activation, and not in SKBR3 and MCF7 cells. This observation is further investigated in vivo. GDC-0941 exhibited minimal tumor inhibition in MDA-MB-231 cells, but it significantly suppressed tumor growth in HER-positive SK-BR3 cells. In vivo mechanism study revealed the activation of WNT/beta-catenin pathway by GDC-0941. A synergistic effect was observed when combined treatment with GDC-0941 and the WNT inhibitor LGK974 at low concentrations in MDA-MB-231 cells. These findings indicated that WNT pathway activation conferred resistance in TNBC cells treated with GDC-0941. This resistance may be further circumvented through combined treatment with pan-PI3K and WNT inhibitors. Future clinical trials of these two inhibitors are warranted.

A phase I pharmacodynamic study of GTI-2040, an antisense oligonucleotide against ribonuclotide reductase, in acute leukemias: a California Cancer Consortium study

We performed a phase I study of GTI-2040, an antisense oligonucleotide against ribonucleotide reductase mRNA, on a novel dosing schedule of days 1-4 and 15-18 by continuous infusion to examine efficacy and tolerability in patients with leukemia. A dose of 11 mg/kg/d was safely reached. Dose-limiting toxicities (DLTs) at the higher levels included elevated troponin I and liver function enzymes. There were no objective responses to GTI-2040 in this study; 7/24 patients were able to complete the predetermined three infusion cycles. Pharmacokinetic and pharmacodynamic studies were performed, indicating a trend towards increasing intracellular drug levels and decreasing RRM2 gene expression with increasing doses. This dose schedule may be considered if appropriate combinations are identified in preclinical studies.

Pilot trial of CRLX101 in patients (pts) with advanced, chemotherapy-refractory gastroesophageal cancer (GEC)

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Background: Camptothecin (CPT) derivatives such as irinotecan have activity in 2nd-line therapy in advanced GEC with reported response rates of 0-15%. CRLX101 is an investigational nanoparticle-drug conjugate (NDC) with a CPT payload. Preclinical evidence indicates preferential uptake in tumors, and animal GEC xenograft models demonstrate superiority of CRLX101 over irinotecan. A pilot trial was conducted at recommended phase 2 dosing (RP2D) to assess preferential uptake of CRLX101 in tumor vs. adjacent normal tissue in endoscopically accessible tumors in patients with chemotherapy-refractory GEC. Data demonstrating preferential tumor uptake of CRLX101 has been presented separately and here we report on the clinical outcomes of patients enrolled. Methods: All pts initiated CRLX101 dosed intravenously at RP2D (15 mg/m2) on days 1 and 15 of a 28-day cycle until disease progression or intolerant toxicity. While detection of preferential CRLX101 tumor uptake was the primary endpoint, with 10 pts enrolled a secondary analysis could be performed with the study having 90% power to detect ≥ 1 responder if the true response rate is ≥ 21%. Responses were assessed using RECIST 1.1. Results: Between Dec. 2012 and Dec. 2014, 10 patients with chemotherapy-refractory (median 2 prior lines of therapy, range 1-4) GEC and adenocarcinoma histology were enrolled and evaluable for response and toxicity. The median time-to-progression was 1.9 mo (range 0.6-8.7 mo). Best response was seen in 1 pt with stable disease (SD) for 8 cycles. Only ≥ grade 3 toxicities related to CRLX101 occurred in a single patient with grade 3 anemia and chest pain who was able to resume therapy without any further toxicity after CRLX101 was reduced to 12 mg/m2. Conclusions: CRLX101 demonstrated minimal activity with SD as best response in this heavily pretreated population. Future efforts with CRLX101 in advanced GEC should focus on combination strategies. Its favorable toxicity profile and evidence of preferential tumor uptake support further clinical research of combining CRLX101 with other targeted therapies such as anti-angiogenesis (ramucirumab) and/or immune checkpoint inhibitors. Clinical trial information: NCT01612546 Clinical trial information: NCT01612546.

Detection of Lysyl Oxidase-Like 2 (LOXL2), a Biomarker of Metastasis from Breast Cancers Using Human Blood Samples

Metastasis accounts for 90% of the mortality associated with breast cancer. Upregulated expression of members of the lysyl oxidase (LOX) family of secreted copper amine oxidases catalyzes the crosslinking of collagens and elastin in the extracellular matrix. LOXs are linked to the development and metastatic progression of breast cancers. Accordingly, aberrant expression of LOX-like 2 (LOXL2) is observed in poorly differentiated, high-grade tumors and is predictive of diseases recurrence, and for decreased overall patient survival. Therefore, LOXL2 expression may serve as a biomarker for breast cancer. Mechanistically, hydrogen peroxide is produced as a byproduct of LOXL2 when using an appropriate substrate, lysine. We exploited this chemistry to generate a revolutionary gold-based electrochemical biosensor capable of accurately detecting nanomolar quantities of LOXL2 in mouse blood, and in human blood samples. Two different sources of the blood samples obtained from breast cancer patients were used in this study indicating the applicability of detecting LOXL2 in breast cancers patients. Limited numbers of urine specimens from breast cancer patients were also tested. Collectively, all of these tests show the promise and potential of this biosensor for detecting LOXL2 as a surrogate biomarker of breast cancer. This work is described in WO 052962 A1 (2014).

PYCR1 and PYCR2 Interact and Collaborate with RRM2B to Protect Cells from Overt Oxidative Stress

Ribonucleotide reductase small subunit B (RRM2B) is a stress response protein that protects normal human fibroblasts from oxidative stress. However, the underlying mechanism that governs this function is not entirely understood. To identify factors that interact with RRM2B and mediate anti-oxidation function, large-scale purification of human Flag-tagged RRM2B complexes was performed. Pyrroline-5-carboxylate reductase 1 and 2 (PYCR1, PYCR2) were identified by mass spectrometry analysis as components of RRM2B complexes. Silencing of both PYCR1 and PYCR2 by expressing short hairpin RNAs induced defects in cell proliferation, partial fragmentation of the mitochondrial network, and hypersensitivity to oxidative stress in hTERT-immortalized human foreskin fibroblasts (HFF-hTERT). Moderate overexpression of RRM2B, comparable to stress-induced level, protected cells from oxidative stress. Silencing of both PYCR1 and PYCR2 completely abolished anti-oxidation activity of RRM2B, demonstrating a functional collaboration of these metabolic enzymes in response to oxidative stress.

Abstract B33: CRLX101, an investigational nanoparticle-drug conjugate, localizes in human tumors and not in adjacent healthy tissue after intravenous dosing

Background: Nanoparticle-based therapeutics are thought to rely on the enhanced permeability and retention effect to preferentially localize in solid tumors and not healthy tissue. These phenomena are rationalized primarily from animal models of the human disease. There is a need to obtain analogous information from humans in order to better understand how nanoparticle-based therapeutics perform in humans. CRLX101 is an investigational nanoparticle drug conjugate (NDC) consisting of a cyclodextrin-containing polymer (CDP) conjugate of the payload camptothecin (CPT). The individual polymer strands self-assemble into nanoparticles (ca. five strands) of approximately 10 to 40 nm diameter and 10 wt% CPT by multiple, interstrand, inclusion complex formation between the cyclodextrin and the CPT molecules. CRLX101 is currently being investigated in phase II trials in patients with renal, ovarian and rectal cancer.

Methods: A phase I clinical trial was performed with CRLX101 at the City of Hope, in patients with advanced or metastatic stomach, gastroesophageal or esophageal cancer. This study was sponsored by City of Hope Medical Center, and funding and CRLX101 was provided by Cerulean Pharma Inc. (ClinicalTrials.gov identifier: NCT01612546). The goal of this study was to test the hypothesis that intact CRLX101 nanoparticles deposit in human tumors and not in normal adjacent tissue after intravenous administration. Tumor and adjacent healthy tissue biopsies were obtained through endoscopic capture from patients who received CRLX101, and analyzed via a number of methodologies.

Results: Both the pre- and post-dosing, healthy tissue samples adjacent to tumors show no evidence of either the NDC or the payload (CPT) contained within the NDC. Similar results are obtained from the pre-dosing tumor samples. However, in 8 of 9 patients that were evaluated, CPT is detected in the tumor tissue by fluorescent microscopy examination of fixed sections. For 3 of these patients, proof of intact CRLX101 NDC is obtained from tissue sections by colocalized, fluorescence from the CPT and a secondary antibody used to stain a PEG specific antibody (binds to the PEG in CRLX101). Following fluorescence imaging, remaining tissues from 3 patients were homogenized and measured for free and CDP conjugated CPT using HPLC. CPT was present in the post-treatment tumor tissue of all 3 patient samples with an average of 96.2±13.1% in the conjugated form, indicating that CRLX101 NDCs are localized in these samples.

Conclusions: Tumor and adjacent healthy tissue biopsies obtained from cancer patients who have received CRLX101show that these NDCs do localize in human tumors and not in adjacent tissues.

Citation Format: Andrew Clark, Devin T. Wiley, Jonathan E. Zuckerman, Paul Webster, Joseph Chao, James Lin, Yun Yen, Mark E. Davis, Scott Eliasof. CRLX101, an investigational nanoparticle-drug conjugate, localizes in human tumors and not in adjacent healthy tissue after intravenous dosing. [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 B33.

Proton pump inhibitors and risk of periampullary cancers--A nested case-control study

Considerable attention has been focused on long-term use of proton pump inhibitor (PPI) medications in relation to increased risk of cancer via stimulation of DNA-damaged cells. The aim of this study is to examine the dose-dependent effect of PPI on periampullary cancers in a national population-based cohort. A nested case-control analysis was constructed based on Taiwan's National Health Insurance Research Database and the Taiwan Cancer Registry between the years 2000 and 2010. Cases involving patients diagnosed with periampullary cancers were selected and controls were matched to cases according to age, sex and observational period. A "PPI user" was defined as any patient receiving more than 28 cumulative defined daily doses as measured by prescription drug claims. Conditional logistic regression analysis was conducted to calculate odds ratios (ORs) and 95% confidence intervals (CIs) according to the level of PPI exposure. A total of 7,681 cases and 76,762 matched controls were included with a mean follow-up period of 6.6 years (SD: 2.0). The odds of PPI exposure in patients with periampullary cancers were higher than that of control patients with an adjusted OR of 1.35 (95% CIs: 1.16-1.57). Our results also showed that PPI exposure was slightly linked to periampullary cancers in dose-dependent manner. A similar association was observed in patients who solely took PPI but no eradication therapy for Helicobacter pylori infection. Long-term PPI use was associated with an increased risk of periampullary cancers in the current population-based study. Physicians must weigh potential risks of long-term maintenance against therapeutic benefit.

Anti-proliferative and gene expression actions of resveratrol in breast cancer cells in vitro

We have used a perfusion bellows cell culture system to investigate resveratrolinduced anti-proliferation/apoptosis in a human estrogen receptor (ER)-negative breast cancer cell line (MDA-MB-231). Using an injection system to perfuse media with stilbene, we showed resveratrol (0.5 – 100 μM) to decrease cell proliferation in a concentration-dependent manner. Comparison of influx and medium efflux resveratrol concentrations revealed rapid disappearance of the stilbene, consistent with cell uptake and metabolism of the agent reported by others. Exposure of cells to 10 μM resveratrol for 4 h daily × 6 d inhibited cell proliferation by more than 60%. Variable extracellular acid-alkaline conditions (pH 6.8 – 8.6) affected basal cell proliferation rate, but did not alter anti-proliferation induced by resveratrol. Resveratrol-induced gene expression, including transcription of the most up-regulated genes and pro-apoptotic p53-dependent genes, was not affected by culture pH changes. The microarray findings in the context of induction of anti-proliferation with brief daily exposure of cells to resveratrol—and rapid disappearance of the compound in the perfusion system—are consistent with existence of an accessible initiation site for resveratrol actions on tumor cells, e.g., the cell surface receptor for resveratrol described on integrin αvβ3.

Abstract 4880: Characterization of genetic concordance between primary tumor cells, circulating tumor cells, and metastatic tumor cells from patients with prostate cancer

Circulating tumor cells (CTCs) which disseminate from the primary tumor site have been found to be a major source of metastatic tumor. However, CTCs are heterogeneous and most CTC DNA is fragmented due to apoptosis. To better understand the molecular pathogenesis of metastasis, it is imperative to obtain single, non-apoptotic CTCs and investigate the genetic concordance between primary tumor cells, CTCs and metastatic tumor cells. Due to the abundance of normal cells present in the blood and in tumor tissue, isolation of single tumor cells or pure cell populations of these cells is extremely difficult. The DEPArray platform is designated to collect single CTCs after Cell-Search enrichment, and to sort pure intact tumor cells from formalin-fixed, paraffin-embedded (FFPE) tissues. Taking advantage of this technology, we have isolated single CTCs from prostate cancer patients. Whole genome amplification was performed and genomes with high integrity were used to evaluate the hotspot mutations in PIK3CA. For comparison, we also made single cell suspensions from FFPE tissue blocks of primary tumors and metastatic tumor in lymph nodes from the same patients. Immunofluorescence staining for cytokeratin (CK) and vimentin (Vim) was performed, followed by isolation of pure tumor cells (CK+), stromal cells (Vim+) and double-positive cells (CK+/Vim+) from both primary tumor and lymph node samples. We plan to do genetic analysis on these cells and compare the results to determine the genetic concordance between primary tumor cells, CTCs and metastatic tumor cells. By using the DEPArray, we have successfully isolated single CTCs, and populations of tumor cells, stromal cells and double-positive cells from primary and metastatic tumors. We will present new data on the genetic concordance between these cells, which will provide new insight into our understanding of metastasis in prostate cancer.

Citation Format: Lixin Yang, Linling Chen, Yafan Wang, Jeremy Jones, Yun Yen, Sofia Loera, Raju Pillai, Peiguo Chu, Dennis Weisenburger. Characterization of genetic concordance between primary tumor cells, circulating tumor cells, and metastatic tumor cells from patients with prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4880. doi:10.1158/1538-7445.AM2015-4880

Abstract 3017: Ribonucleotide reductase promotes uracil-mediated genome instability in tumor progression

The elevation of RRM2A subunit of ribonucleotide reductase (RNR) has been shown oncogenic and associated with human cancers. However, the molecular mechanism of RRM2A in cancer promotion is unclear. In this study, we investigated whether RNR-mediated dUTP formation is involved in promoting genome instability. Since dUTP is degraded by dUTPase, we analyzed the expression of RRM2A and dUTPase in clinical samples from colorectal and breast cancer patients. The results revealed that high RRM2A and low dUTPase in tumors are correlated with poorer survival. In cancer cell lines that express high level of RRM2A and dUTPase, knockdown of dUTPase increases genome instability. Conversely, overexpression of dUTPase reduces genome stress in cancer cells expressing high RRM2A and low dUTPase. In non-tumorigenic cells, overexpression of RRM2A increases replication stress and genome instability accompanied by higher levels of 53BP1 foci and increased breaks at AT-rich fragile sites bound by 53BP1. Thymidine supplement in growth medium or co-expression of dUTPase was able to reduce RRM2A-mediated replication stress and 53BP1 foci. We further provide evidence that RRM2A promotes replication stress and error prone-translesion synthesis dependent on uracil DNA glycosylase. These results suggest that up-regulation of RRM2A in tumor cells increases uracil-mediated replication stress to promote genome instability. Therefore, high RRM2A/low dUTPase context confers tumor genome evolution advantage, correlating with poorer prognosis.

Citation Format: Chih-Wei Chen, Ning Tsao, Yun Yen, Christine E. Lehman, Yuh-Hwa Wang, Chian-Feng Chen, Tse-Hsiang Wu, Sui-Chih Tien, Ming-Hsiang Lee, Zee-Fen Chang. Ribonucleotide reductase promotes uracil-mediated genome instability in tumor progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3017. doi:10.1158/1538-7445.AM2015-3017

Tumor suppressor FOXO3 regulates ribonucleotide reductase subunit RRM2B and impacts on survival of cancer patients

The role of Ribonucleotide reductase (RR) subunits in different cancers has been intensively studied in our laboratory. RRM2B was identified as a p53-inducible RR subunit that involves in various critical cellular mechanisms such as cell cycle regulation, DNA repair and replication, and mitochondrial homeostasis, etc. However, little is known about the p53-independent regulation of RRM2B in cancer pathology. In this study, we discovered tumor suppressor FOXO3 as the novel regulator of RRM2B. FOXO3 directly bound to and transcriptionally activated the promoter of RRM2B, and induced the expression of RRM2B at RNA and protein levels. Moreover, Overexpression of RRM2B and/or FOXO3 inhibited the proliferation of cancer cells. The cancer tissue microarray data also demonstrated a strong correlation between the co-expression of FOXO3 plus RRM2B and increased disease survival and reduced recurrence or metastasis in lung cancer patients. Our results suggest a novel regulatory control of RRM2B function, and imply the importance of FOXO signaling pathway in DNA replication modulation. This study provides the first time evidence that RRM2B is transcriptionally and functionally regulated independent of p53 pathway by FOXO3, and it establishes that FOXO3 and RRM2B could be used as predictive biomarkers for cancer progression.