Targeting nucleotide metabolism enhances the efficacy of anthracyclines and anti-metabolites in triple-negative breast cancer

Triple-negative breast cancer (TNBC) remains the most lethal breast cancer subtype with poor response rates to the current chemotherapies and a lack of additional effective treatment options. We have identified deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase) as a critical gatekeeper that protects tumour DNA from the genotoxic misincorporation of uracil during treatment with standard chemotherapeutic agents commonly used in the FEC regimen. dUTPase catalyses the hydrolytic dephosphorylation of deoxyuridine triphosphate (dUTP) to deoxyuridine monophosphate (dUMP), providing dUMP for thymidylate synthase as part of the thymidylate biosynthesis pathway and maintaining low intracellular dUTP concentrations. This is crucial as DNA polymerase cannot distinguish between dUTP and deoxythymidylate triphosphate (dTTP), leading to dUTP misincorporation into DNA. Targeting dUTPase and inducing uracil misincorporation during the repair of DNA damage induced by fluoropyrimidines or anthracyclines represents an effective strategy to induce cell lethality. dUTPase inhibition significantly sensitised TNBC cell lines to fluoropyrimidines and anthracyclines through imbalanced nucleotide pools and increased DNA damage leading to decreased proliferation and increased cell death. These results suggest that repair of treatment-mediated DNA damage requires dUTPase to prevent uracil misincorporation and that inhibition of dUTPase is a promising strategy to enhance the efficacy of TNBC chemotherapy.

Changes in body-related self-conscious emotions over time among youth female athletes

The current study explored change in body-related self-conscious emotions (e.g., shame, guilt, authentic pride, hubristic pride) over three years, and tested body surveillance, age, weight status, years in sport, and competitive status as baseline predictors of change. Adolescent females engaged in organized sport (N = 518 at baseline, M_age = 14.02, SD = 1.38 years) completed a self-report survey once a year for three years (n = 293 and n = 215 in Years 2 and 3, respectively). Based on the unconditional latent growth model, body-related shame and guilt increased over time, and authentic and hubristic pride decreased over time. There was substantial between-person variability in the intercepts for all emotions and slopes for shame, guilt, and hubristic pride. In the conditional parallel process latent growth model, body surveillance predicted shallower change in shame and guilt over time. Female athletes high in body surveillance also reported higher body-related shame and guilt and lower authentic and hubristic pride at baseline. These findings highlight the importance of studying changes in self-conscious emotions over time in sport, and demonstrate that body surveillance may be an important factor to explore in interventions early in development.

Standards of reporting: the use of CONSORT PRO and CERT in individuals living with osteoporosis

The Consolidated Standards of Reporting Trials for Patient-Reported Outcomes (CONSORT PRO) and the Consensus on Exercise Reporting Template (CERT) have been developed to improve the quality and transparency of reporting standards in scientific research. The purpose of this study was to provide evidence for the adoption of CONSORT PRO and CERT by researchers examining the link between exercise and quality of life in individuals living with osteoporosis. A systematic search was conducted to identify randomized control trials published in English evaluating exercise interventions on quality of life in individuals living with osteoporosis. Reporting standards were assessed using CONSORT PRO and CERT. A total of 127 studies were identified with 23 meeting inclusion criteria. "Good" evidence for eight (42.1%) CONSORT PRO and two (12.5%) CERT items was found. Adherence to CONSORT PRO was not related to the year of publication, journal impact factor, or study quality. Adherence to CONSORT PRO and CERT reporting standards is inadequate in the literature examining exercise interventions on quality of life in individuals living with osteoporosis. Sufficient reporting is paramount to knowledge translation, interpretation by interventionists, and clinician confidence in understanding if (and how) exercise is associated with quality of life outcomes in this cohort. Concerns associated with failure to include this information are highlighted.

A Phase II Biomarker-Embedded Study of Lapatinib plus Capecitabine as First-line Therapy in Patients with Advanced or Metastatic Gastric Cancer

An exploratory phase II biomarker-embedded trial (LPT109747; NCT00526669) designed to determine the association of lapatinib-induced fluoropyrimidine gene changes with efficacy of lapatinib plus capecitabine as first-line treatment for advanced gastric cancer or gastroesophageal junction adenocarcinoma independent of tumor HER2 status. Tumor biopsies obtained before and after 7-day lapatinib (1,250 mg) to analyze changes in gene expression, followed by a 14-day course of capecitabine (1,000 mg/m(2) twice daily, 14/21 days) plus lapatinib 1,250 mg daily. Blood samples were acquired for pharmacokinetic analysis. Primary clinical objectives were response rate (RR) and 5-month progression-free survival (PFS). Secondary objectives were overall survival (OS), PFS, time to response, duration of response, toxicity, and identification of associations between lapatinib pharmacokinetics and biomarker endpoints. Primary biomarker objectives were modulation of 5-FU-pathway genes by lapatinib, effects of germline SNPs on treatment outcome, and trough steady-state plasma lapatinib concentrations. Sixty-eight patients were enrolled; (75% gastric cancer, 25% gastroesophageal junction). Twelve patients (17.9%) had confirmed partial response, 31 (46.3%) had stable disease, and 16 (23.9%) had progressive disease. Median PFS and OS were 3.3 and 6.3 months, respectively. Frequent adverse events included diarrhea (45%), decreased appetite (39%), nausea (36%), and fatigue (36%). Lapatinib induced no changes in gene expression from baseline and no significant associations were found for SNPs analyzed. Elevated baseline HER3 mRNA expression was associated with a higher RR (33% vs. 0%; P = 0.008). Lapatinib plus capecitabine was well tolerated, demonstrating modest antitumor activity in patients with advanced gastric cancer. The association of elevated HER3 and RR warrants further investigation as an important player for HER-targeted regimens in combination with capecitabine. Mol Cancer Ther; 15(9); 2251-8. ©2016 AACR.

Solution-stable anisotropic carbon nanotube/graphene hybrids based on slanted columnar thin films for chemical sensing

Because of their structural anisotropy and stability in liquids, carbon nanotube/graphene hybrid structures are promising for biosensing applications, as shown in a proof-of-concept experiment on in situ ellipsometry monitoring of pyrene-functionalized DNA attachment.

Few-layered titanium trisulfide (TiS3) field-effect transistors

Titanium trisulfide (TiS3) is a promising layered semiconductor material. Several-mm-long TiS3 whiskers can be conveniently grown by the direct reaction of titanium and sulfur. In this study, we exfoliated these whiskers using the adhesive tape approach and fabricated few-layered TiS3 field-effect transistors (FETs). The TiS3 FETs showed an n-type electronic transport with room-temperature field-effect mobilities of 18-24 cm(2) V(-1) s(-1) and ON/OFF ratios up to 300. We demonstrate that TiS3 is compatible with the conventional atomic layer deposition (ALD) procedure for Al2O3. ALD of alumina on TiS3 FETs resulted in mobility increase up to 43 cm(2) V(-1) s(-1), ON/OFF ratios up to 7000, and much improved subthreshold swing characteristics. This study shows that TiS3 is a competitive electronic material in the family of two-dimensional (2D) transition metal chalcogenides and can be considered for emerging device applications.

Multilayer graphitic coatings for thermal stabilization of metallic nanostructures

We demonstrate that graphitic coatings, which consist of multilayer disordered graphene sheets, can be used for the thermal protection of delicate metal nanostructures. We studied cobalt slanted nanopillars grown by glancing angle deposition that were shown to melt at temperatures much lower than the melting point of bulk cobalt. After graphitic coatings were conformally grown over the surfaces of Co nanopillars by chemical vapor deposition, the resulting carbon-coated Co nanostructures retained their morphology at elevated temperatures, which would damage the uncoated structures. Thermal stabilization is also demonstrated for carbon-coated Ti nanopillars. The results of this study may be extended to other metallic and possibly even nonmetallic nanostructures that need to preserve their morphology at elevated temperatures in a broad range of applications.

Oxidative peeling of carbon black nanoparticles

We demonstrate that layered carbon black nanoparticles can be oxidatively peeledviathe reaction with potassium permanganate in sulfuric acid.

Standing the test of time: targeting thymidylate biosynthesis in cancer therapy

Over the past 60 years, chemotherapeutic agents that target thymidylate biosynthesis and the enzyme thymidylate synthase (TS) have remained among the most-successful drugs used in the treatment of cancer. Fluoropyrimidines, such as 5-fluorouracil and capecitabine, and antifolates, such as methotrexate and pemetrexed, induce a state of thymidylate deficiency and imbalances in the nucleotide pool that impair DNA replication and repair. TS-targeted agents are used to treat numerous solid and haematological malignancies, either alone or as foundational therapeutics in combination treatment regimens. We overview the pivotal discoveries that led to the rational development of thymidylate biosynthesis as a chemotherapeutic target, and highlight the crucial contribution of these advances to driving and accelerating drug development in the earliest era of cancer chemotherapy. The function of TS as well as the mechanisms and consequences of inhibition of this enzyme by structurally diverse classes of drugs with distinct mechanisms of action are also discussed. In addition, breakthroughs relating to TS-targeted therapies that transformed the clinical landscape in some of the most-difficult-to-treat cancers, such as pancreatic, colorectal and non-small-cell lung cancer, are highlighted. Finally, new therapeutic agents and novel mechanism-based strategies that promise to further exploit the vulnerabilities and target resistance mechanisms within the thymidylate biosynthesis pathway are reviewed.

Insulin-like growth factor receptor polymorphism defines clinical outcome in estrogen receptor-positive breast cancer patients treated with tamoxifen

Compelling evidence points to a key role for insulin-like growth factor 1 (IGF1) signaling in breast cancer development and progression. In addition, IGF1 receptor (IGF1R) expression has been correlated and functionally linked with estrogen receptor (ER) signaling. Recent translational studies support a cross talk between IGF1R and ERα at different levels and data suggest enhanced IGF1R signaling as a causative mechanism of tamoxifen (TAM) resistance. We tested whether functional germline variations in the IGF pathway are associated with clinical outcome in ER-positive primary invasive breast cancer patients, who were treated with surgery and adjuvant TAM. Tissue samples of 222 patients with ER+ primary invasive breast cancer, who had undergone surgery at Charing Cross Hospital, London, UK between 1981 and 2003, were analyzed. Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue samples and six functional IGF1 pathway polymorphisms were analyzed using direct DNA sequencing and PCR-restriction fragment length polymorphism. In multivariable analysis, patients with primary invasive breast cancer carrying IGF1R_rs2016347 G allele had a significantly increased risk of early tumor progression (hazard ratio (HR) 2.01; adjusted P=0.004) and death (HR 1.84; adjusted P=0.023) compared with patients carrying G/T or T/T, independent of established clinicopathological determinants. This association remained significant after adjusting for multiple testing. In addition, we were able to demonstrate that IRS1_rs1801123 and IGFBP3_rs2854744 were significantly associated with lymph node involvement and tumor size, respectively. We provide the first evidence for IGF1R_rs2016347 as an independent prognostic marker for ER+ breast cancer patients treated with TAM and support a rational for combined treatment strategies.

Sustained inhibition of deacetylases is required for the antitumor activity of the histone deactylase inhibitors panobinostat and vorinostat in models of colorectal cancer

Despite compelling preclinical data in colorectal cancer (CRC), the efficacy of HDACIs has been disappointing in the clinic. The goal of this study was to evaluate the effectiveness of vorinostat and panobinostat in a dose- and exposure-dependent manner in order to better understand the dynamics of drug action and antitumor efficacy. In a standard 72 h drug exposure MTS assay, notable concentration-dependent antiproliferative effects were observed in the IC50 range of 1.2-2.8 μmol/L for vorinostat and 5.1-17.5 nmol/L for panobinostat. However, shorter clinically relevant exposures of 3 or 6 h failed to elicit any significant growth inhibition and in most cases a >24 h exposure to vorinostat or panobinostat was required to induce a sigmoidal dose-response. Similar results were observed in colony formation assays where ≥ 24 h of exposure was required to effectively reduce colony formation. Induction of acetyl-H3, acetyl-H4 and p21 by vorinostat were transient and rapidly reversed within 12 h of drug removal. In contrast, panobinostat-induced acetyl-H3, acetyl-H4, and p21 persisted for 48 h after an initial 3 h exposure. Treatment of HCT116 xenografts with panobinostat induced significant increases in acetyl-H3 and downregulation of thymidylate synthase after treatment. Although HDACIs exert both potent growth inhibition and cytotoxic effects when CRC cells were exposed to drug for ≥ 24 h, these cells demonstrate an inherent ability to survive HDACI concentrations and exposure times that exceed those clinically achievable. Continued efforts to develop novel HDACIs with improved pharmacokinetics/phamacodynamics, enhanced intratumoral delivery and class/isoform-specificity are needed to improve the therapeutic potential of HDACIs and HDACI-based combination regimens in solid tumors.

Intratumoral expression profiling of genes involved in angiogenesis in colorectal cancer patients treated with chemotherapy plus the VEGFR inhibitor PTK787/ZK 222584 (vatalanib)

The phase III CONFIRM clinical trials demonstrated that metastatic colorectal cancer patients with elevated serum lactate dehydrogenase (LDH) had improved outcome when the vascular endothelial growth factor receptor (VEGFR) inhibitor PTK/ZK (Vatalanib) was added to FOLFOX4 chemotherapy. We investigated the hypothesis that high intratumoral expression of genes regulated by hypoxia-inducible factor-1 alpha (HIF1α), namely LDHA, glucose transporter-1 (GLUT-1), VEGFA, VEGFR1, and VEGFR2, were predictive of outcome in CONFIRM-1. Tumor tissue was isolated by laser-capture microdissection from 85 CONFIRM-1 tumor specimens; FOLFOX4/placebo n=42, FOLFOX4/PTK/ZK n=43. Gene expression was analyzed using quantitative RT-PCR. In univariate analyses, elevated mRNA expression of LDHA, GLUT-1, and VEGFR1 were associated with response to FOLFOX4/PTK/ZK. In univariate and multivariate analyses, elevated LDHA and VEGFR1 mRNA levels were associated with improved progression-free survival in FOLFOX4/PTK/ZK patients. Furthermore, increased HIF1α and VEGFR2 mRNA levels were associated with decreased survival in FOLFOX/placebo patients but not in patients who received FOLFOX4/PTK/ZK. These are the first data suggesting intratumoral mRNA expression of genes involved in angiogenesis/HIF pathway may predict outcome to VEGFR-inhibitors. Biomarkers that assist in directing VEGFR-inhibitors toward patients with an increased likelihood of benefit will improve the cost-effectiveness of these promising agents.

An individual coding polymorphism and the haplotype of the SPARC gene predict gastric cancer recurrence

The 5-year survival rate for gastric adenocarcinoma (GA) remains only 40% and biomarkers to identify patients at high risk of tumor recurrence are urgently needed. Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein that mediates cell matrix interactions, and upregulation of SPARC can promote tumor progression and metastasis. This study investigated whether single-nucleotide polymorphisms (SNPs) in SPARC impact the prognosis of GA. Blood or formalin-fixed, paraffin-embedded tissues were obtained from 137 GA patients at the University of Southern California and Memorial Sloan-Kettering Cancer Center medical facilities. DNA was isolated and five SNPs in the SPARC 3'-untranslated region (UTR) were evaluated by DNA sequencing or PCR-restriction fragment length polymorphism. Associations between SNPs and time to tumor recurrence (TTR) were analyzed using Kaplan-Meier curves, log-rank tests, and likelihood-ratio test within logistic or Cox regression model as appropriate. Patients carrying at least one G allele of the SPARC rs1059829 polymorphism (GG, AG) showed a median TTR of 3.7 years compared with 2.1 years TTR for patients with AA (hazard ratio (HR) 0.57; P=0.033). In a multivariate analysis adjusted for T and N category as covariates and stratified by race, hospital and chemotherapy, patients with at least one SPARC rs1059829 G allele (GG, AG) remained significantly associated with superior TTR than patients with AA genotype (adjusted P=0.026). In addition, patients harboring the G-A-A haplotype had the highest risk of tumor recurrence (HR 1.892; adjusted P=0.016). Our findings suggest that SPARC 3'-UTR SNPs may be useful in predicting GA patients at increased risk of recurrence.

An individual coding polymorphism and the haplotype of the SPARC gene predict gastric cancer recurrence

The 5-year survival rate for gastric adenocarcinoma (GA) remains only 40% and biomarkers to identify patients at high risk of tumor recurrence are urgently needed. Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein that mediates cell matrix interactions, and upregulation of SPARC can promote tumor progression and metastasis. This study investigated whether single-nucleotide polymorphisms (SNPs) in SPARC impact the prognosis of GA. Blood or formalin-fixed, paraffin-embedded tissues were obtained from 137 GA patients at the University of Southern California and Memorial Sloan-Kettering Cancer Center medical facilities. DNA was isolated and five SNPs in the SPARC 3'-untranslated region (UTR) were evaluated by DNA sequencing or PCR-restriction fragment length polymorphism. Associations between SNPs and time to tumor recurrence (TTR) were analyzed using Kaplan-Meier curves, log-rank tests, and likelihood-ratio test within logistic or Cox regression model as appropriate. Patients carrying at least one G allele of the SPARC rs1059829 polymorphism (GG, AG) showed a median TTR of 3.7 years compared with 2.1 years TTR for patients with AA (hazard ratio (HR) 0.57; P=0.033). In a multivariate analysis adjusted for T and N category as covariates and stratified by race, hospital and chemotherapy, patients with at least one SPARC rs1059829 G allele (GG, AG) remained significantly associated with superior TTR than patients with AA genotype (adjusted P=0.026). In addition, patients harboring the G-A-A haplotype had the highest risk of tumor recurrence (HR 1.892; adjusted P=0.016). Our findings suggest that SPARC 3'-UTR SNPs may be useful in predicting GA patients at increased risk of recurrence.

Inhibition of dUTPase induces synthetic lethality with thymidylate synthase-targeted therapies in non-small cell lung cancer

Chemotherapies that target thymidylate synthase (TS) continue to see considerable clinical expansion in non-small cell lung cancer (NSCLC). One drawback to TS-targeted therapies is drug resistance and subsequent treatment failure. Novel therapeutic and biomarker-driven strategies are urgently needed. The enzyme deoxyuridine triphosphate nucleotidohydrolase (dUTPase) is reported to protect tumor cells from aberrant misincorporation of uracil during TS inhibition. The goal of this study was to investigate the expression and significance of dUTPase in mediating response to TS-targeted agents in NSCLC. The expression of dUTPase in NSCLC cell lines and clinical specimens was measured by quantitative real-time reverse transcriptase PCR and immunohistochemistry. Using a validated RNA interference approach, dUTPase was effectively silenced in a panel of NSCLC cell lines and response to the fluoropyrimidine fluorodeoxyuridine (FUdR) and the antifolate pemetrexed was analyzed using growth inhibition and clonogenic assays. Apoptosis was analyzed by flow cytometry. Significant variation in the quantity and cellular expression of dUTPase was observed, including clear evidence of overexpression in NSCLC cell line models and tumor specimens at the mRNA and protein level. RNA interference-mediated silencing of dUTPase significantly sensitized NSCLC cells to growth inhibition induced by FUdR and pemetrexed. This sensitization was accompanied by a significant expansion of intracellular dUTP pools and significant decreases in NSCLC cell viability evaluated by clonogenicity and apoptotic analyses. Together, these results strongly suggest that uracil misincorporation is a potent determinant of cytotoxicity to TS inhibition in NSCLC and that inhibition of dUTPase is a mechanism-based therapeutic approach to significantly enhance the efficacy of TS-targeted chemotherapeutic agents.

The Cyclin D1 (CCND1) A870G polymorphism predicts clinical outcome to lapatinib and capecitabine in HER2-positive metastatic breast cancer

BACKGROUND

Lapatinib plus capecitabine emerged as an efficacious therapy in metastatic breast cancer (mBC). We aimed to identify germline single-nucleotide polymorphisms (SNPs) in genes involved in capecitabine catabolism and human epidermal receptor signaling that were associated with clinical outcome to assist in selecting patients likely to benefit from this combination.

PATIENTS AND METHODS

DNA was extracted from 240 of 399 patients enrolled in EGF100151 clinical trial (NCT00078572; clinicaltrials.gov) and SNPs were successfully evaluated in 234 patients. The associations between SNPs and clinical outcome were analyzed using Fisher's exact test, Kaplan-Meier curves, log-rank tests, likelihood ratio test within logistic or Cox regression model, as appropriate.

RESULTS

There were significant interactions between CCND1 A870G and clinical outcome. Patients carrying the A-allele were more likely to benefit from lapatinib plus capecitabine versus capecitabine when compared with patients harboring G/G (P = 0.022, 0.024 and 0.04, respectively). In patients with the A-allele, the response rate (RR) was significantly higher with lapatinib plus capecitabine (35%) compared with capecitabine (11%; P = 0.001) but not between treatments in patients with G/G (RR = 24% and 32%, respectively; P = 0.85). Time to tumor progression (TTP) was longer in patients with the A-allele treated with lapatinib plus capecitabine compared with capecitabine (median TTP = 7.9 and 3.4 months; P < 0.001), but not in patients with G/G (median TTP = 6.1 and 6.6 months; P = 0.92).

CONCLUSION

Our findings suggest that CCND1A870G may be useful in predicting clinical outcome in HER2-positive mBC patients treated with lapatinib plus capecitabine.

Common cancer stem cell gene variants predict colon cancer recurrence

PURPOSE

Recent evidence suggests that cancer stem cells (CSC) are responsible for key elements of colon cancer progression and recurrence. Germline variants in CSC genes may result in altered gene function and/or activity, thereby causing interindividual differences in a patient's tumor recurrence capacity and chemoresistance. We investigated germline polymorphisms in a comprehensive panel of CSC genes to predict time to tumor recurrence (TTR) in patients with stage III and high-risk stage II colon cancer.

EXPERIMENTAL DESIGN

A total of 234 patients treated with 5-fluorouracil-based chemotherapy at the University of Southern California were included in this study. Whole blood samples were analyzed for germline polymorphisms in genes that have been previously associated with colon CSC (CD44, Prominin-1, DPP4, EpCAM, ALCAM, Msi-1, ITGB1, CD24, LGR5, and ALDH1A1) by PCR-RFLP or direct DNA-sequencing.

RESULTS

The minor alleles of CD44 rs8193 C>T, ALCAM rs1157 G>A, and LGR5 rs17109924 T>C were significantly associated with increased TTR (9.4 vs. 5.4 years; HR, 0.51; 95% CI: 0.35-0.93; P = 0.022; 11.3 vs. 5.7 years; HR, 0.56; 95% CI: 0.33-0.94; P = 0.024, and 10.7 vs. 5.7 years; HR, 0.33; 95% CI: 0.12-0.90; P = 0.023, respectively) and remained significant in the multivariate analysis stratified by ethnicity. In recursive partitioning, a specific gene variant profile including LGR5 rs17109924, CD44 rs8193, and ALDH1A1 rs1342024 represented a high-risk subgroup with a median TTR of 1.7 years (HR, 6.71, 95% CI: 2.71-16.63, P < 0.001).

CONCLUSION

This is the first study identifying common germline variants in colon CSC genes as independent prognostic markers for stage III and high-risk stage II colon cancer patients.

Pharmacogenetic angiogenesis profiling for first-line Bevacizumab plus oxaliplatin-based chemotherapy in patients with metastatic colorectal cancer

PURPOSE

There is substantial germline genetic variability within angiogenesis pathway genes, thereby causing interindividual differences in angiogenic capacity and resistance to antiangiogenesis therapy. We investigated germline polymorphisms in genes involved in VEGF-dependent and -independent angiogenesis pathways to predict clinical outcome and tumor response in metastatic colorectal cancer (mCRC) patients treated with bevacizumab and oxaliplatin-based chemotherapy.

EXPERIMENTAL DESIGN

A total of 132 patients treated with first-line bevacizumab and FOLFOX or XELOX were included in this study. Genomic DNA was isolated from whole-blood samples by PCR-RFLP or direct DNA sequencing. The endpoints of the study were progression-free survival (PFS), overall survival (OS), and response rate (RR).

RESULTS

The minor alleles of EGF rs444903 A>G and IGF-1 rs6220 A>G were associated with increased OS and remained significant in multivariate Cox regression analysis (HR: 0.52; 95% CI: 0.31-0.87; adjusted P = 0.012 and HR: 0.60; 95% CI: 0.36-0.99; adjusted P = 0.046, respectively). The minor allele of HIF1α rs11549465 C>T was significantly associated with increased PFS but lost its significance in multivariate analysis. CXCR1 rs2234671 G>C, CXCR2 rs2230054 T>C, EGFR rs2227983 G>A, and VEGFR-2 rs2305948 C>T predicted tumor response, with CXCR1 rs2234671 G>C remaining significant in multiple testing (P(act) = 0.003).

CONCLUSION

In this study, we identified common germline variants in VEGF-dependent and -independent angiogenesis genes predicting clinical outcome and tumor response in patients with mCRC receiving first-line bevacizumab and oxaliplatin-based chemotherapy.

Calbindin 2 (CALB2) regulates 5-fluorouracil sensitivity in colorectal cancer by modulating the intrinsic apoptotic pathway

The role of the calcium binding protein, Calbindin 2 (CALB2), in regulating the response of colorectal cancer (CRC) cells to 5-Fluorouracil (5-FU) was investigated. Real-time RT-PCR and Western blot analysis revealed that CALB2 mRNA and protein expression were down-regulated in p53 wild-type and p53 null isogenic HCT116 CRC cell lines following 48 h and 72 h 5-FU treatment. Moreover, 5-FU-induced apoptosis was significantly reduced in HCT116 and LS174T CRC cell lines in which CALB2 expression had been silenced. Further investigation revealed that CALB2 translocated to the mitochondria following 5-FU treatment and that 5-FU-induced loss of mitochondrial membrane potential (Δψ(m)) was abrogated in CALB2-silenced cells. Furthermore, CALB2 silencing decreased 5-FU-induced cytochrome c and smac release from the mitochondria and also decreased 5-FU-induced activation of caspases 9 and 3/7. Of note, co-silencing of XIAP overcame 5-FU resistance in CALB2-silenced cells. Collectively, these results suggest that following 5-FU treatment in CRC cell lines, CALB2 is involved in apoptosis induction through the intrinsic mitochondrial pathway. This indicates that CALB2 may be an important mediator of 5-FU-induced cell death. Moreover, down-regulation of CALB2 in response to 5-FU may represent an intrinsic mechanism of resistance to this anti-cancer drug.

A novel fluorescence-based assay for the rapid detection and quantification of cellular deoxyribonucleoside triphosphates

Current methods for measuring deoxyribonucleoside triphosphates (dNTPs) employ reagent and labor-intensive assays utilizing radioisotopes in DNA polymerase-based assays and/or chromatography-based approaches. We have developed a rapid and sensitive 96-well fluorescence-based assay to quantify cellular dNTPs utilizing a standard real-time PCR thermocycler. This assay relies on the principle that incorporation of a limiting dNTP is required for primer-extension and Taq polymerase-mediated 5–3′ exonuclease hydrolysis of a dual-quenched fluorophore-labeled probe resulting in fluorescence. The concentration of limiting dNTP is directly proportional to the fluorescence generated. The assay demonstrated excellent linearity (R² > 0.99) and can be modified to detect between ∼0.5 and 100 pmol of dNTP. The limits of detection (LOD) and quantification (LOQ) for all dNTPs were defined as <0.77 and <1.3 pmol, respectively. The intra-assay and inter-assay variation coefficients were determined to be <4.6% and <10%, respectively with an accuracy of 100 ± 15% for all dNTPs. The assay quantified intracellular dNTPs with similar results obtained from a validated LC–MS/MS approach and successfully measured quantitative differences in dNTP pools in human cancer cells treated with inhibitors of thymidylate metabolism. This assay has important application in research that investigates the influence of pathological conditions or pharmacological agents on dNTP biosynthesis and regulation.

Interleukin-8 is associated with proliferation, migration, angiogenesis and chemosensitivity in vitro and in vivo in colon cancer cell line models

Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, is known to possess tumorigenic and proangiogenic properties. Overexpression of IL-8 has been detected in many human tumors, including colorectal cancer (CRC), and is associated with poor prognosis. The goal of our study was to determine the role of IL-8 overexpression in CRC cells in vitro and in vivo. We stably transfected the IL-8 cDNA into two human colon cancer cell lines, HCT116 and Caco2, and selected IL-8-secreting transfectants. Real-time RT-PCR confirmed that IL-8 mRNA was overexpressed in IL-8 transfectants with 45- to 85-fold higher than parental cells. The IL-8-transfected clones secreted 19- to 28-fold more IL-8 protein than control and parental cells as detected by ELISA. The IL-8 transfectants demonstrated increased cellular proliferation, cell migration and invasion based on functional assays. Growth inhibition studies showed that IL-8 overexpression lead to a significant resistance to oxaliplatin (p < 0.0001). Inhibition of IL-8 overexpression with small interfering RNA reversed the observed increases in tumorigenic functions and oxaliplatin resistance, suggesting that IL-8 not only provides a proliferative advantage but also promotes the metastatic potential of colon cancer cells. Using a tumor xenograft model, IL-8-expressing cells formed significantly larger tumors than the control cells with increased microvessel density. Together, these findings indicate that overexpression of IL-8 promotes tumor growth, metastasis, chemoresistance and angiogenesis, implying IL-8 to be an important therapeutic target in CRC.

Interleukin-8 is associated with proliferation, migration, angiogenesis and chemosensitivity in vitro and in vivo in colon cancer cell line models

Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, is known to possess tumorigenic and proangiogenic properties. Overexpression of IL-8 has been detected in many human tumors, including colorectal cancer (CRC), and is associated with poor prognosis. The goal of our study was to determine the role of IL-8 overexpression in CRC cells in vitro and in vivo. We stably transfected the IL-8 cDNA into two human colon cancer cell lines, HCT116 and Caco2, and selected IL-8-secreting transfectants. Real-time RT-PCR confirmed that IL-8 mRNA was overexpressed in IL-8 transfectants with 45- to 85-fold higher than parental cells. The IL-8-transfected clones secreted 19- to 28-fold more IL-8 protein than control and parental cells as detected by ELISA. The IL-8 transfectants demonstrated increased cellular proliferation, cell migration and invasion based on functional assays. Growth inhibition studies showed that IL-8 overexpression lead to a significant resistance to oxaliplatin (p < 0.0001). Inhibition of IL-8 overexpression with small interfering RNA reversed the observed increases in tumorigenic functions and oxaliplatin resistance, suggesting that IL-8 not only provides a proliferative advantage but also promotes the metastatic potential of colon cancer cells. Using a tumor xenograft model, IL-8-expressing cells formed significantly larger tumors than the control cells with increased microvessel density. Together, these findings indicate that overexpression of IL-8 promotes tumor growth, metastasis, chemoresistance and angiogenesis, implying IL-8 to be an important therapeutic target in CRC.

Interleukin-8 is associated with proliferation, migration, angiogenesis and chemosensitivity in vitro and in vivo in colon cancer cell line models

Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, is known to possess tumorigenic and proangiogenic properties. Overexpression of IL-8 has been detected in many human tumors, including colorectal cancer (CRC), and is associated with poor prognosis. The goal of our study was to determine the role of IL-8 overexpression in CRC cells in vitro and in vivo. We stably transfected the IL-8 cDNA into two human colon cancer cell lines, HCT116 and Caco2, and selected IL-8-secreting transfectants. Real-time RT-PCR confirmed that IL-8 mRNA was overexpressed in IL-8 transfectants with 45- to 85-fold higher than parental cells. The IL-8-transfected clones secreted 19- to 28-fold more IL-8 protein than control and parental cells as detected by ELISA. The IL-8 transfectants demonstrated increased cellular proliferation, cell migration and invasion based on functional assays. Growth inhibition studies showed that IL-8 overexpression lead to a significant resistance to oxaliplatin (p < 0.0001). Inhibition of IL-8 overexpression with small interfering RNA reversed the observed increases in tumorigenic functions and oxaliplatin resistance, suggesting that IL-8 not only provides a proliferative advantage but also promotes the metastatic potential of colon cancer cells. Using a tumor xenograft model, IL-8-expressing cells formed significantly larger tumors than the control cells with increased microvessel density. Together, these findings indicate that overexpression of IL-8 promotes tumor growth, metastasis, chemoresistance and angiogenesis, implying IL-8 to be an important therapeutic target in CRC.

The dual EGFR/HER2 inhibitor lapatinib synergistically enhances the antitumor activity of the histone deacetylase inhibitor panobinostat in colorectal cancer models

As key molecules that drive progression and chemoresistance in gastrointestinal cancers, epidermal growth factor receptor (EGFR) and HER2 have become efficacious drug targets in this setting. Lapatinib is an EGFR/HER2 kinase inhibitor suppressing signaling through the RAS/RAF/MEK (MAP/ERK kinase)/MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase)/AKT pathways. Histone deacetylase inhibitors (HDACi) are a novel class of agents that induce cell cycle arrest and apoptosis following the acetylation of histone and nonhistone proteins modulating gene expression and disrupting HSP90 function inducing the degradation of EGFR-pathway client proteins. This study sought to evaluate the therapeutic potential of combining lapatinib with the HDACi panobinostat in colorectal cancer (CRC) cell lines with varying EGFR/HER2 expression and KRAS/BRAF/PIK3CA mutations. Lapatinib and panobinostat exerted concentration-dependent antiproliferative effects in vitro (panobinostat range 7.2-30 nmol/L; lapatinib range 7.6-25.8 μmol/L). Combined lapatinib and panobinostat treatment interacted synergistically to inhibit the proliferation and colony formation in all CRC cell lines tested. Combination treatment resulted in rapid induction of apoptosis that coincided with increased DNA double-strand breaks, caspase-8 activation, and PARP cleavage. This was paralleled by decreased signaling through both the PI3K and MAPK pathways and increased downregulation of transcriptional targets including NF-κB1, IRAK1, and CCND1. Panobinostat treatment induced downregulation of EGFR, HER2, and HER3 mRNA and protein through transcriptional and posttranslational mechanisms. In the LoVo KRAS mutant CRC xenograft model, the combination showed greater antitumor activity than either agent alone, with no apparent increase in toxicity. Our results offer preclinical rationale warranting further clinical investigation combining HDACi with EGFR and HER2-targeted therapies for CRC treatment.

GRP78 promoter polymorphism rs391957 as potential predictor for clinical outcome in gastric and colorectal cancer patients

BACKGROUND

Recently, the analysis of gastric and colorectal tumor specimens determined that 78-kiloDalton glucose-regulated protein (GRP78), an endoplasmic reticulum chaperone, up-regulation serves as an efficient mechanism protecting cells against apoptosis and can confer drug resistance. We tested whether functional polymorphisms within the GRP78 gene are related to clinical outcome in gastric and colorectal cancer (CRC) patients.

PATIENTS AND METHODS

Blood samples of 234 stage II/III CRC patients at the University of Southern California (USC) and formalin-fixed paraffin-embedded tissues of 137 patients with localized gastric adenocarcinoma (GA) at USC and Memorial Sloan-Kettering Cancer Centers were obtained. GRP78 polymorphisms analyzed on germline DNA were correlated with clinical outcome using univariate and multivariate analyses.

RESULTS

GA patients with the combined GRP78 rs391957 C/T and T/T genotype were at higher risk for tumor recurrence and death [hazard ratio (HR) 2.61; P < 0.001 and HR 3.17; P < 0.001, respectively], than those with C/C. These findings were subsequently tested in a CRC cohort where patients with the homozygous T/T genotype were at highest risk for tumor recurrence (HR 2.61; P = 0.015). The results remained significant after adjusting for clinicopathologic determinants.

CONCLUSION

These data provide the first evidence that the GRP78 rs391957 polymorphism can predict clinical outcome in localized GA and locally advanced CRC patients.

Germline polymorphisms in genes involved in the CD44 signaling pathway are associated with clinical outcome in localized gastric adenocarcinoma

The cluster of differentiation 44 (CD44) signaling pathway is crucial in cancer-cell growth, invasion, proliferation and metastasis. CD44 is a transmembrane receptor for hyaluronan and osteopontin, and has recently attracted attention as a gastric cancer stem cell marker. Previous studies showed that polymorphisms in the CD44 gene can influence both human cancer survival and determine cellular response to cytotoxic chemotherapeutics. In addition, CD44 protein overexpression has been associated with poor prognosis in gastric adenocarcinoma (GA). We tested the hypothesis whether polymorphisms involved in the CD44 pathway will predict clinical outcome in patients with localized GA. Either blood or formalin-fixed paraffin-embedded (FFPE) tissues were obtained from 137 patients with localized GA at University of Southern California and Memorial Sloan-Kettering Cancer Center medical facilities. DNA was isolated and polymorphisms within the CD44 pathway were determined by PCR-RFLP technique. In univariate analysis CD44 rs187116 and CD44 rs7116432 were significantly associated with time to tumor recurrence (TTR) and overall survival (OS). After adjusting for covariates, patients harboring at least one G allele of CD44 rs187116 remained significantly associated with TTR (adjusted p=0.009) and OS (adjusted p=0.045). Further, patients harboring CD44 T-A haplotype were at the lowest risk of developing tumor recurrence (HR: 0.255; 95% CI: 0.11-0.591; adjusted p=0.001) and death (HR 0.198; 95% CI: 0.07-0.563; adjusted p=0.002). These results provide the first evidence that CD44 polymorphisms predict clinical outcome in patients with localized GA. This may help to identify localized GA patients at high risk for tumor recurrence.

Germline polymorphisms in genes involved in the IGF1 pathway predict efficacy of cetuximab in wild-type KRAS mCRC patients

PURPOSE

The insulin-like growth factor 1 (IGF1) signaling pathway is an important growth-regulatory pathway, which plays a crucial role in colorectal cancer (CRC) proliferation, differentiation, migration, angiogenesis, and apoptosis. Previous studies showed that hyperactivation of the IGF1 receptor (IGF1R) may result in resistance to anti-epidermal growth factor receptor-targeted treatment. We tested whether germline variations within the IGF1 pathway are associated with clinical outcome in wild-type (wt) KRAS drug-refractory metastatic CRC (mCRC) patients who were treated with cetuximab monotherapy (IMC-0144).

EXPERIMENTAL DESIGN

Formalin-fixed, paraffin-embedded (FFPE) tissue samples of 130 drug-refractory mCRC patients enrolled in IMC-0144, a phase II clinical trial of cetuximab monotherapy, were analyzed. gDNA was extracted from dissected FFPE tumor tissue, and KRAS mutation status and six potentially functional IGF1 and IGF1R polymorphisms were analyzed using direct DNA sequencing or PCR-RFLP. Tumor response analysis was based on recursive partitioning, and survival analyses were based on univariate and multivariate hazard regression models.

RESULTS

In univariate and multivariate analyses, five IGF pathway single-nucleotide polymorphisms were significantly associated with progression-free survival (PFS) and/or overall survival (OS). In multivariate combined risk allele analysis, the additive model for PFS and OS was significantly associated with the number of risk alleles in wt KRAS patients (P = 0.001 and P = 0.02, respectively). In addition, wt KRAS patients harboring IGF1 rs2946834 A/A genotype had a 50% objective response rate compared with 0% for A/G genotype.

CONCLUSIONS

These results indicate that IGF1 pathway polymorphisms are potential predictive/prognostic molecular markers for cetuximab efficacy in wt KRAS mCRC patients. Prospective biomarker-embedded clinical trials are warranted to validate our findings. Clin Cancer Res; 16(22); 5591-602. ©2010 AACR.

A let-7 microRNA-binding site polymorphism in 3'-untranslated region of KRAS gene predicts response in wild-type KRAS patients with metastatic colorectal cancer treated with cetuximab monotherapy

PURPOSE

recent studies have found that KRAS mutations predict resistance to monoclonal antibodies targeting the epidermal growth factor receptor in metastatic colorectal cancer (mCRC). A polymorphism in a let-7 microRNA complementary site (lcs6) in the KRAS 3' untranslated region (UTR) is associated with an increased cancer risk in non-small-cell lung cancer and reduced overall survival (OS) in oral cancers. We tested the hypothesis whether this polymorphism may be associated with clinical outcome in KRAS wild-type (KRASwt) mCRC patients treated with cetuximab monotherapy.

PATIENTS AND METHODS

the presence of KRAS let-7 lcs6 polymorphism was evaluated in 130 mCRC patients who were enrolled in a phase II study of cetuximab monotherapy (IMCL-0144). Genomic DNA was extracted from dissected formalin-fixed paraffin-embedded tumor tissue, KRAS mutation status and polymorphism were assessed using direct sequencing and PCR restriction fragment length polymorphism technique.

RESULTS

KRAS let-7 lcs6 polymorphism was found to be related to object response rate (ORR) in mCRC patients whose tumors had KRASwt. The 12 KRASwt patients harboring at least a variant G allele (TG or GG) had a 42% ORR compared with a 9% ORR in 55 KRASwt patients with let-7 lcs6 TT genotype (P = 0.02, Fisher's exact test). KRASwt patients with TG/GG genotypes had trend of longer median progression-free survival (3.9 versus 1.3 months) and OS (10.7 versus 6.4 months) compared to those with TT genotypes.

CONCLUSIONS

these results are the first to indicate that the KRAS 3'UTR polymorphism may predict for cetuximab responsiveness in KRASwt mCRC patients, which warrants validation in other clinical trials.

A let-7 microRNA-binding site polymorphism in 3'-untranslated region of KRAS gene predicts response in wild-type KRAS patients with metastatic colorectal cancer treated with cetuximab monotherapy

PURPOSE

recent studies have found that KRAS mutations predict resistance to monoclonal antibodies targeting the epidermal growth factor receptor in metastatic colorectal cancer (mCRC). A polymorphism in a let-7 microRNA complementary site (lcs6) in the KRAS 3' untranslated region (UTR) is associated with an increased cancer risk in non-small-cell lung cancer and reduced overall survival (OS) in oral cancers. We tested the hypothesis whether this polymorphism may be associated with clinical outcome in KRAS wild-type (KRASwt) mCRC patients treated with cetuximab monotherapy.

PATIENTS AND METHODS

the presence of KRAS let-7 lcs6 polymorphism was evaluated in 130 mCRC patients who were enrolled in a phase II study of cetuximab monotherapy (IMCL-0144). Genomic DNA was extracted from dissected formalin-fixed paraffin-embedded tumor tissue, KRAS mutation status and polymorphism were assessed using direct sequencing and PCR restriction fragment length polymorphism technique.

RESULTS

KRAS let-7 lcs6 polymorphism was found to be related to object response rate (ORR) in mCRC patients whose tumors had KRASwt. The 12 KRASwt patients harboring at least a variant G allele (TG or GG) had a 42% ORR compared with a 9% ORR in 55 KRASwt patients with let-7 lcs6 TT genotype (P = 0.02, Fisher's exact test). KRASwt patients with TG/GG genotypes had trend of longer median progression-free survival (3.9 versus 1.3 months) and OS (10.7 versus 6.4 months) compared to those with TT genotypes.

CONCLUSIONS

these results are the first to indicate that the KRAS 3'UTR polymorphism may predict for cetuximab responsiveness in KRASwt mCRC patients, which warrants validation in other clinical trials.

Abstract 5438: A novel therapeutic combination with synergistic antitumor activity in colon cancer: The dual tyrosine kinase inhibitor lapatinib and the histone deacetylase inhibitor LBH589

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States. Effective treatment is hindered by the high incidence of drug resistance and tumor recurrence, resulting in the need to identify and exploit novel therapeutic targets and drug combinations to improve clinical efficacy. The epidermal growth factor receptor (EGFR) has been implicated in colon cancer growth, progression and chemoresistance and inhibition of EGFR has therefore become an efficacious drug target. Lapatinib is a dual tyrosine kinase inhibitor targeting EGFR and HER-2 and suppressing oncogenic signaling through the RAS-RAF-MEK-ERK and PI3K/AKT pathways. Histone deacetylase inhibitors (HDACi) are a novel class of agents demonstrating promising activity against colon cancer cells through the hyper-acetylation of histone and non-histone proteins resulting in cell cycle arrest and apoptosis. HDACi are also reported to disrupt HSP90 function, inducing the degradation of EGFR-pathway client proteins (e.g. EGFR, HER-2, BRAF). This study sought to evaluate the therapeutic potential of lapatinib in combination with the HDACi LBH589 (Panobinostat) in a panel of eight colon cancer cell lines with varying EGFR/HER-2 expression and KRAS mutational status. EGFR and HER-2 mRNA and protein expression levels were determined by quantitative PCR and Western blot. Concentration-dependent antiproliferative effects of both lapatinib and LBH589 were observed in vitro (lapatinib range 7.6-15.8 μM; LBH589 range 7.2-30 nM) using the MTS assay. The combination of LBH589 and lapatinib interacted synergistically to inhibit both cell proliferation and colony formation in all colon cancer cell lines tested. Combination treatment resulted in decreased signaling through both the PI3K and MAPK pathways as determined by decreased levels of phospho-AKT and phospho-p44/42 MAPK. Co-treatment with lapatinib and LBH589 also resulted in the rapid induction of apoptosis as early as 18 h post-treatment as determined by flow cytometry and Western blot analysis of apoptotic factors including cleaved caspase-8 and PARP. These in vitro observations were extended to a LoVo colon cancer xenograft model where combination treatment resulted in greater antitumor activity than either lapatinib or LBH589 alone, with no apparent increase in toxicity. Together these data provide scientific rationale warranting further investigation of HDACi in combination with EGFR and HER-2-targeted therapies for the treatment of colorectal cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5438.

Abstract A4: Identification of novel histone deacetylase inhibitor-regulated drug targets and a phase I/II trial of vorinostat in combination with 5-fluorouracil in metastatic colorectal cancer

Histone deacetylase inhibitors (HDACi) represent a novel class of agents that are undergoing clinical evaluation in colorectal cancer (CRC). Previously, we identified that HDACi including vorinostat (Vor) and LBH589 induced downregulation of the 5-FU target enzyme thymidylate synthase (TS) resulting in the sensitization of CRC cells to 5-FU. There were two goals in the present study: Firstly to identify additional genes in CRC cells that are differentially regulated by two clinically advanced HDACi, Vor and LBH589, furthering our understanding of their mechanism of action and to identify potential targets for novel HDACi-based drug combinations. Secondly, to extend our preclinical observations and evaluate the safety and feasibility of combining Vor with 5-FU in a phase I/II trial in patients with metastatic CRC (mCRC) and elevated intratumoral TS who had failed 5-FU-based therapy. HCT116 and HT29 CRC cells treated with Vor and LBH589 were analyzed using the Illumina Human-6 V2 BeadChip array. Differentially expressed genes (DEGs) were subject to hierarchical clustering, venn diagram analysis and interpreted using Ingenuity® Pathway Analysis. Results from microarray analysis were validated by quantitative PCR (qPCR) and analyzed in a panel of 8 CRC cell lines in vitro and in HCT116 and HT29 xenograft models. Bioinformatic analysis of the microarray results revealed significant similarity in DEGs following treatment with the two HDACi tested within each cell line. However, analysis of in the HCT116 and HT29 cells revealed cell-line-specific responses to HDACi treatment. In addition a core cassette of 11 DEGs modulated by both Vor and LBH589 were identified in both CRC cell lines analyzed and further validated in a panel of 8 CRC cell lines and in HCT116 and HT29 xenograft models treated with LBH589. This study identified HDACi-induced alterations in critical genes involved in nucleotide metabolism, angiogenesis, mitosis and cell survival which may represent potential intervention points for novel HDACi-based drug combinations in CRC. We concurrently conducted a Phase I/II clinical trial to determine the safety and feasibility of combining Vor with 5-FU in patients with mCRC and elevated intratumoral TS. Patients who had failed all standard therapeutic options were eligible. Intratumoral TS mRNA expression and peripheral blood mononuclear cell (PBMC) histone acetylation were measured before and after 6 consecutive days of Vor treatment at 400 mg PO daily. 5-FU/LV were given on days 6 and 7 and repeated every 2 wks, along with continuous daily Vor. Ten patients were enrolled and three dose levels were explored in the phase I portion of the study. Two dose-limiting toxicities (DLTs) were observed at the starting dose level, resulting in de-escalation to levels −1 and −2. Given the occurrence of two DLTs at each of the dose levels, we were unable to establish a maximum tolerated dose (MTD). Two patients achieved significant disease stabilization for 4 and 6 months. Grade 3 and 4 toxicities included fatigue, thrombocytopenia and mucositis. Intratumoral TS downregulation ≥50% was observed in one patient only. Acetylation of histone 3 was observed in PBMCs following Vor treatment. The study failed to establish a MTD and was terminated. The presence of PBMC histone acetylation indicates biological activity of Vor, however, consistent reductions in intratumoral TS mRNA were not observed. Alternate Vor dose-scheduling may alleviate the toxicity, achieve optimal TS downregulation and improve efficacy.

Citation Information: Clin Cancer Res 2010;16(7 Suppl):A4

A phase I/II trial of vorinostat in combination with 5-fluorouracil in patients with metastatic colorectal cancer who previously failed 5-FU-based chemotherapy

PURPOSE

We conducted a phase I/II clinical trial to determine the safety and feasibility of combining vorinostat with 5-fluorouracil (5-FU) in patients with metastatic colorectal cancer (mCRC) and elevated intratumoral thymidylate synthase (TS).

METHODS

Patients with mCRC who had failed all standard therapeutic options were eligible. Intratumoral TS mRNA expression and peripheral blood mononuclear cell (PBMC) histone acetylation were measured before and after 6 consecutive days of vorinostat treatment at 400 mg PO daily. 5-FU/LV were given on days 6 and 7 and repeated every 2 weeks, along with continuous daily vorinostat. Dose escalation occurred in cohorts of three to six patients.

RESULTS

Ten patients were enrolled. Three dose levels were explored in the phase I portion of the study. Two dose-limiting toxicities (DLTs) were observed at the starting dose level, which resulted in dose de-escalation to levels -1 and -2. Given the occurrence of two DLTs at each of the dose levels, we were unable to establish a maximum tolerated dose (MTD). Two patients achieved significant disease stabilization for 4 and 6 months. Grade 3 and 4 toxicities included fatigue, thrombocytopenia and mucositis. Intratumoral TS downregulation > or = 50% was observed in one patient only. Acetylation of histone 3 was observed in PBMCs following vorinostat treatment.

CONCLUSIONS

The study failed to establish a MTD and was terminated. The presence of PBMC histone acetylation indicates biological activity of vorinostat, however, consistent reductions in intratumoral TS mRNA were not observed. Alternate vorinostat dose-scheduling may alleviate the toxicity and achieve optimal TS downregulation.

The dual EGFR/HER-2 tyrosine kinase inhibitor lapatinib sensitizes colon and gastric cancer cells to the irinotecan active metabolite SN-38

Members of the human epidermal receptor (HER) family are frequently associated with aggressive disease and poor prognosis in multiple malignancies. Lapatinib is a dual tyrosine kinase inhibitor targeting the epidermal growth factor receptor (EGFR) and HER-2. This study evaluated the therapeutic potential of lapatinib, alone and in combination with SN-38, the active metabolite of irinotecan (CPT-11), in colon and gastric cancer cell lines. Concentration-dependent antiproliferative effects of both lapatinib and SN-38 were observed in all colon and gastric cancer cell lines tested but varied significantly between individual cell lines (lapatinib range 0.08-11.7 muM; SN-38 range 3.6-256 nM). Lapatinib potently inhibited the growth of a HER-2 overexpressing gastric cancer cell line and demonstrated moderate activity in gastric and colon cancer cells with detectable HER-2 expression. The combination of lapatinib and SN-38 interacted synergistically to inhibit cell proliferation in all colon and gastric cancer cell lines tested. Cotreatment with lapatinib and SN-38 also resulted in enhanced cell cycle arrest and the induction of apoptosis with subsequent cellular pharmacokinetic analysis demonstrating that lapatinib promoted the increased intracellular accumulation and retention of SN-38 when compared to SN-38 treatment alone. Finally, the combination of lapatinib and CPT-11 demonstrated synergistic antitumor efficacy in the LoVo colon cancer mouse xenograft model with no apparent increase in toxicity compared to CPT-11 monotherapy. These results provide compelling preclinical rationale indicating lapatinib to be a potentially efficacious chemotherapeutic combination partner for irinotecan in the treatment of gastrointestinal carcinomas.

DNA microarray profiling of genes differentially regulated by the histone deacetylase inhibitors vorinostat and LBH589 in colon cancer cell lines

BACKGROUND

Despite the significant progress made in colon cancer chemotherapy, advanced disease remains largely incurable and novel efficacious chemotherapies are urgently needed. Histone deacetylase inhibitors (HDACi) represent a novel class of agents which have demonstrated promising preclinical activity and are undergoing clinical evaluation in colon cancer. The goal of this study was to identify genes in colon cancer cells that are differentially regulated by two clinically advanced hydroxamic acid HDACi, vorinostat and LBH589 to provide rationale for novel drug combination partners and identify a core set of HDACi-regulated genes.

METHODS

HCT116 and HT29 colon cancer cells were treated with LBH589 or vorinostat and growth inhibition, acetylation status and apoptosis were analyzed in response to treatment using MTS, Western blotting and flow cytometric analyses. In addition, gene expression was analyzed using the Illumina Human-6 V2 BeadChip array and Ingenuity Pathway Analysis.

RESULTS

Treatment with either vorinostat or LBH589 rapidly induced histone acetylation, cell cycle arrest and inhibited the growth of both HCT116 and HT29 cells. Bioinformatic analysis of the microarray profiling revealed significant similarity in the genes altered in expression following treatment with the two HDACi tested within each cell line. However, analysis of genes that were altered in expression in the HCT116 and HT29 cells revealed cell-line-specific responses to HDACi treatment. In addition a core cassette of 11 genes modulated by both vorinostat and LBH589 were identified in both colon cancer cell lines analyzed.

CONCLUSION

This study identified HDACi-induced alterations in critical genes involved in nucleotide metabolism, angiogenesis, mitosis and cell survival which may represent potential intervention points for novel therapeutic combinations in colon cancer. This information will assist in the identification of novel pathways and targets that are modulated by HDACi, providing much-needed information on HDACi mechanism of action and providing rationale for novel drug combination partners. We identified a core signature of 11 genes which were modulated by both vorinostat and LBH589 in a similar manner in both cell lines. These core genes will assist in the development and validation of a common gene set which may represent a molecular signature of HDAC inhibition in colon cancer.

Histone deacetylase inhibitors suppress thymidylate synthase gene expression and synergize with the fluoropyrimidines in colon cancer cells

Despite recent therapeutic advances, the response rates to chemotherapy for patients with metastatic colon cancer remain at approximately 50% with the fluoropyrimidine, 5-fluorouracil (5-FU), continuing to serve as the foundation chemotherapeutic agent for the treatment of this disease. Previous studies have demonstrated that overexpression of thymidylate synthase (TS) is a key determinant of resistance to 5-FU-based chemotherapy. Therefore, there is a significant need to develop alternative therapeutic strategies to overcome TS-mediated resistance. In this study, we demonstrate that the histone deacetylase inhibitors (HDACi) vorinostat and LBH589 significantly downregulate TS gene expression in a panel of colon cancer cell lines. Downregulation of TS was independent of p53, p21 and HDAC2 expression and was achievable in vivo as demonstrated by mouse xenograft models. We provide evidence that HDACi treatment leads to a potent transcriptional repression of the TS gene. Combination of the fluoropyrimidines 5-FU or FUdR with both vorinostat and LBH589 enhanced cell cycle arrest and growth inhibition. Importantly, the downstream effects of TS inhibition were significantly enhanced by this combination including the inhibition of acute TS induction and the enhanced accumulation of the cytotoxic nucleotide intermediate dUTP. These data demonstrate that HDACi repress TS expression at the level of transcription and provides the first evidence suggesting a direct mechanistic link between TS downregulation and the synergistic interaction observed between HDACi and 5-FU. This study provides rationale for the continued clinical evaluation of HDACi in combination with 5-FU-based therapies as a strategy to overcome TS-mediated resistance.

Polymorphisms in cyclooxygenase-2 and epidermal growth factor receptor are associated with progression-free survival independent of K-ras in metastatic colorectal cancer patients treated with single-agent cetuximab

PURPOSE

Recently, an objective response rate of 12% was reported in a phase II study of cetuximab in patients with epidermal growth factor receptor (EGFR)-expressing metastatic colorectal cancer (mCRC) refractory to fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy (IMC-0144). In this large molecular correlates study, we tested whether K-ras mutation status and polymorphisms in genes involved in the EGFR-signaling pathway were associated with clinical outcome in IMC-0144.

EXPERIMENTAL DESIGN

We analyzed all available tissue samples from 130 of 346 mCRC patients enrolled in the IMC-0144 phase II clinical trial of cetuximab. Genomic DNA was extracted from formalin-fixed paraffin-embedded tumor tissues, and K-ras mutation status and the genotypes were analyzed using PCR-RFLP, direct DNA-sequencing, and 5'-end [gamma-33P] ATP-labeled PCR-protocols.

RESULTS

The PFS of patients with cyclooxygenase-2 (COX-2) -765 G>C [C/C; risk ratio (RR), 0.31; 95% confidence interval (95% CI), 0.12-0.84; P = 0.032], COX-2 +8473 T>C (C/C; RR, 0.67; 95% CI, 0.40-1.13; P = 0.003), EGF +61 A>G (G/G; RR, 0.57; 95% CI, 0.34-0.95; P = 0.042), and EGFR +497 G>A (A/G; RR, 0.82; 95% CI, 0.56-1.20; P = 0.017) genotypes was significantly longer compared with those with other genotypes. In addition, patients whose tumors did not have K-ras mutations showed better RR, PFS, and overall survival than patients with K-ras mutations. In multivariable analysis, COX-2 +8473 T>C (adjusted P = 0.013) and EGFR +497 G>A (adjusted P = 0.010) remained significantly associated with progression-free survival, independent of skin rash toxicity, K-ras mutation status, and Eastern Cooperative Group performance status.

CONCLUSIONS

Polymorphisms in COX-2 and EGFR may be useful independent molecular markers to predict clinical outcome in patients with mCRC treated with single-agent cetuximab, independent of skin rash toxicity, K-ras mutation, and Eastern Cooperative Oncology Group performance status.

Regulation of human dUTPase gene expression and p53-mediated transcriptional repression in response to oxaliplatin-induced DNA damage

Deoxyuridine triphosphate nucleotidohydrolase (dUTPase) catalyzes the hydrolysis of dUTP to dUMP and PPi. Although dUTP is a normal intermediate in DNA synthesis, its accumulation and misincorporation into DNA is lethal. Importantly, uracil misincorporation is a mechanism of cytotoxicity induced by fluoropyrimidine chemotherapeutic agents including 5-fluorouracil (5-FU) and elevated expression of dUTPase is negatively correlated with clinical response to 5-FU-therapy. In this study we performed the first functional characterization of the dUTPase promoter and demonstrate a role for E2F-1 and Sp1 in driving dUTPase expression. We establish a direct role for both mutant and wild-type forms of p53 in modulating dUTPase promoter activity. Treatment of HCT116 p53(+/+) cells with the DNA-damaging agent oxaliplatin induced a p53-dependent transcriptional downregulation of dUTPase not observed in the isogenic null cell line. Oxaliplatin treatment induced enrichment of p53 at the dUTPase promoter with a concomitant reduction in Sp1. The suppression of dUTPase by oxaliplatin promoted increased levels of dUTP that was enhanced by subsequent addition of fluoropyrimidines. The novel observation that oxaliplatin downregulates dUTPase expression may provide a mechanistic basis contributing to the synergy observed between 5-FU and oxaliplatin in the clinic. Furthermore, these studies provide the first evidence of a direct transcriptional link between the essential enzyme dUTPase and the tumor suppressor p53.

Novel opportunities for thymidylate metabolism as a therapeutic target

For over 40 years, the fluoropyrimidine 5-fluorouracil (5-FU) has remained the central agent in therapeutic regimens employed in the treatment of colorectal cancer and is frequently combined with the DNA-damaging agents oxaliplatin and irinotecan, increasing response rates and improving overall survival. However, many patients will derive little or no benefit from treatment, highlighting the need to identify novel therapeutic targets to improve the efficacy of current 5-FU-based chemotherapeutic strategies. dUTP nucleotidohydrolase (dUTPase) catalyzes the hydrolysis of dUTP to dUMP and PPi, providing substrate for thymidylate synthase (TS) and DNA synthesis and repair. Although dUTP is a normal intermediate in DNA synthesis, its accumulation and misincorporation into DNA as uracil is lethal. Importantly, uracil misincorporation represents an important mechanism of cytotoxicity induced by the TS-targeted class of chemotherapeutic agents including 5-FU. A growing body of evidence suggests that dUTPase is an important mediator of response to TS-targeted agents. In this article, we present further evidence showing that elevated expression of dUTPase can protect breast cancer cells from the expansion of the intracellular uracil pool, translating to reduced growth inhibition following treatment with 5-FU. We therefore report the implementation of in silico drug development techniques to identify and develop small-molecule inhibitors of dUTPase. As 5-FU and the oral 5-FU prodrug capecitabine remain central agents in the treatment of a variety of malignancies, the clinical utility of a small-molecule inhibitor to dUTPase represents a viable strategy to improve the clinical efficacy of these mainstay chemotherapeutic agents.

Evidence for a multidimensional self-efficacy for exercise scale

This series of three studies considers the multidimensionality of exercise self-efficacy by examining the psychometric characteristics of an instrument designed to assess three behavioral subdomains: task, scheduling, and coping. In Study 1, exploratory factor analysis revealed the expected factor structure in a sample of 395 students. Confirmatory factor analysis (CFA) confirmed these results in a second sample of 282 students. In Study 2, the generalizability of the factor structure was confirmed with CFA in a randomly selected sample of 470 community adults, and discriminant validity was supported by theoretically consistent distinctions among exercisers and nonexercisers. In Study 3, change in self-efficacy in conjunction with adoption of novel exercise was examined in a sample of 58 women over 12 weeks. Observed changes in the three self-efficacy domains appeared to be relatively independent. Together, the three studies support a multidimensional conceptualization of exercise self-efficacy that can be assessed and appears to be sensitive to change in exercise behavior.

Exploring alternative individualized treatment strategies in colorectal cancer

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in men and women in the United States, with a predicted 154,000 new cases this year. For > 40 years, 5-fluorouracil (5-FU) has remained the central agent in therapeutic regimens used in the treatment of CRC, with single-agent response rates (RRs) of 20%-25% in advanced-stage disease. The past decade has witnessed the introduction of newer agents, such as the DNA-damaging agents oxaliplatin and irinotecan, which when used in combination with 5-FU, have dramatically increased RRs to 40%-50% in advanced disease and improved overall survival. The development of monoclonal antibodies targeting the epidermal growth factor receptor or vascular endothelial growth factor have now demonstrated additional clinical benefit for patients with metastatic disease, and the clinical development of these agents continues to progress. However, many patients will die, and a significant proportion will experience severe chemotherapy-induced toxicities, while deriving little or no benefit. Global efforts are currently under way to identify reliable and validated cassettes of markers with the ability to predict response and toxicity from a chemotherapeutic regimen. In addition, the ability to accurately predict patients with early-stage disease at high risk of recurrence will enable the appropriate administration of adjuvant therapy. The emerging cancer stem cell hypothesis continues to gain momentum with ongoing research, suggesting this might become one of the prime targets for future therapy. Together, these approaches are spearheading a paradigm shift toward individualized treatment strategies in CRC treatment.

Predictive and prognostic markers in colorectal cancer

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in both men and women in the United States, with an estimated 153,760 new cases predicted for 2007. Since the 1960s, 5-fluorouracil (5-FU) has remained the mainstay of therapeutic options in the treatment of advanced CRC, with response rates of 20% to 25%. The introduction of newer agents such as oxaliplatin and irinotecan in combination with 5-FU has increased response rates to 40% to 50% in advanced disease and improved overall survival. The development of monoclonal antibodies targeting the epidermal growth factor receptor or vascular endothelial growth factor has demonstrated additional clinical benefit for patients with metastatic disease. However, many patients succumb to their disease, and a significant proportion will experience severe chemotherapy-associated toxicities while deriving little or no benefit. To improve the treatment of CRC, efforts must be directed toward the identification of patients who are likely to respond to a specific therapy, those who will experience severe toxicities, and those who will benefit from chemotherapy in the adjuvant setting. However, the utility of individual markers of response, toxicity, and disease recurrence remains in question. Efforts are now under way to develop multimarker profiles that can more accurately predict disease response. In this review, we discuss both predictive and prognostic markers identified in the treatment of CRC in terms of their robustness and their ability to assist the clinician in developing the most efficacious and least toxic therapeutic strategy for each patient.

The role of spermidine/spermine N1-acetyltransferase in determining response to chemotherapeutic agents in colorectal cancer cells

Polyamines have been shown to play a role in the growth and survival of several solid tumors, including colorectal cancer. We identified the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) as being one of the most highly inducible genes in two DNA microarray screens to identify novel determinants of response to chemotherapeutic agents in colorectal cancer. SSAT was shown to be inducible in response to 5-fluorouracil (5-FU) or oxaliplatin in parental and drug-resistant HCT116 cell lines. It was also shown that SSAT mRNA was up-regulated in response to 5-FU or oxaliplatin in a panel of six colorectal cancer cell lines. The polyamine analogue N(1),N(11)-diethylnorspermine (DENSpm) depletes polyamine pools and potently induces SSAT. We evaluated the effect of combining DENSpm with chemotherapeutic agents in HCT116 p53(+/+) cells and in HCT116 drug-resistant daughter cell lines. Western blot analyses showed that SSAT protein expression was dramatically enhanced when DENSpm was combined with oxaliplatin or 5-FU in HCT116 p53(+/+) cells. Using cell viability assays and flow cytometry, synergistic induction of cell death was observed following cotreatment of HCT116 p53(+/+) cells with DENSpm and each chemotherapeutic agent. Of note, this combined therapy increased the chemosensitivity of cells rendered resistant to each of these chemotherapeutic agents. Small interfering RNA-mediated down-regulation of SSAT resulted in loss of synergy between DENSpm and these agents. These results show that SSAT plays an important role in regulating cell death following combined cytotoxic drug and DENSpm treatment. Furthermore, DENSpm sensitizes both sensitive and resistant cells to chemotherapeutic agents. Taken together, these results suggest that SSAT may be an important target for therapeutic intervention in colorectal cancer.

Pharmacogenomic identification of novel determinants of response to chemotherapy in colon cancer

DNA microarray analysis was used to analyze the transcriptional profile of HCT116 colorectal cancer cells that were treated with 5-fluorouracil (5-FU) or oxaliplatin and selected for resistance to these agents. Bioinformatic analyses identified sets of genes that were constitutively dysregulated in drug-resistant cells and transiently altered following acute exposure of parental cells to drug. We propose that these genes may represent molecular signatures of sensitivity to 5-FU and oxaliplatin. Using real-time reverse transcription-PCR (RT-PCR), the robustness of our microarray data was shown with a strong overall concordance of expression trends for > or =82% (oxaliplatin) and > or =85% (5-FU) of a representative subset of genes. Furthermore, strong correlations between the microarray and real-time RT-PCR measurements of average fold changes in gene expression were observed for both the 5-FU (R(2) > or = 0.73) and oxaliplatin gene sets (R(2) > or = 0.63). Functional analysis of three genes identified in the microarray study [prostate-derived factor (PDF), calretinin, and spermidine/spermine N(1)-acetyl transferase (SSAT)] revealed their importance as novel regulators of cytotoxic drug response. These data show the power of this novel microarray-based approach to identify genes which may be important markers of response to treatment and/or targets for therapeutic intervention.

Case report of a 13-year-old struck by lightning

Lightning strikes kill 1,000 people per year worldwide. Cardiac arrests resulting from lightning strikes have good survival rates but there is a significant degree of morbidity amongst the survivors. This is the case report of a 13-year-old boy who had a cardiac arrest following a direct lightning strike, and his subsequent management.

A policy analysis of the Expert Patient in the United Kingdom: self-care as an expression of pastoral power?

The rise in chronic illness and comorbidity in Western society has resulted in an increasing emphasis on self-care initiatives. In the United Kingdom this is exemplified by the Expert Patient policy. This paper discusses the Expert Patient initiative as an example of the State's third way approach to public health. The extent to which this policy challenges conventional power relationships between professional and patient, and fosters equal partnership is examined. In particular, how expert is defined and whether a professional understanding of the term is reconcilable with a patient's expertise is debated. The paper argues that the Expert Patient initiative is unlikely to reconstruct chronic illness and may further complicate the State's responsibility in meeting the needs of those with chronic illness. Issues of power within self-care are explored to illuminate the policy, and this paper argues that the Expert Patient initiative is an example of Foucault's notion of pastoral power. Although the Expert Patient policy focuses on the rights and responsibilities of those with chronic illness, this paper concludes that there is no corresponding strategy to challenge professionals' assumptions toward those with chronic illness.

Systematic review of water fluoridation

OBJECTIVE

To review the safety and efficacy of fluoridation of drinking water.

DESIGN

Search of 25 electronic databases and world wide web. Relevant journals hand searched; further information requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity.

MAIN OUTCOME MEASURES

Decayed, missing, and filled primary/permanent teeth. Proportion of children without caries. Measure of effect was the difference in change in prevalence of caries from baseline to final examination in fluoridated compared with control areas. For potential adverse effects, all outcomes reported were used.

RESULTS

214 studies were included. The quality of studies was low to moderate. Water fluoridation was associated with an increased proportion of children without caries and a reduction in the number of teeth affected by caries. The range (median) of mean differences in the proportion of children without caries was -5.0% to 64% (14.6%). The range (median) of mean change in decayed, missing, and filled primary/permanent teeth was 0.5 to 4.4 (2.25) teeth. A dose-dependent increase in dental fluorosis was found. At a fluoride level of 1 ppm an estimated 12.5% (95% confidence interval 7.0% to 21.5%) of exposed people would have fluorosis that they would find aesthetically concerning.

CONCLUSIONS

The evidence of a beneficial reduction in caries should be considered together with the increased prevalence of dental fluorosis. There was no clear evidence of other potential adverse effects.