Expression of transketolase-like 1 protein (TKTL1) in human endometrial cancer

Malignant tumors metabolize glucose to lactate even in the presence of oxygen (aerobic glycolysis). The metabolic switch from oxidative glycolysis to non-oxidative fermentation of glucose and proteins performed by the tumor cells seems to be associated with TKTL1 and pAkt overexpression. Therefore the aim of the present study was to investigate the expression of TKTL1 and pAkt in human specimens of endometrial cancer as compared to benign endometrium. Additionally, expression of the glucose transporter GLUT1 was also investigated as aerobic glycolysis is associated with an increased need for glucose.

O-GlcNAc transferase integrates metabolic pathways to regulate the stability of c-MYC in human prostate cancer cells

Metabolic disruptions that occur widely in cancers offer an attractive focus for generalized treatment strategies. The hexosamine biosynthetic pathway (HBP) senses metabolic status and produces an essential substrate for O-linked β-N-acetylglucosamine transferase (OGT), which glycosylates and thereby modulates the function of its target proteins. Here, we report that the HBP is activated in prostate cancer cells and that OGT is a central regulator of c-Myc stability in this setting. HBP genes were overexpressed in human prostate cancers and androgen regulated in cultured human cancer cell lines. Immunohistochemical analysis of human specimens (n = 1987) established that OGT is upregulated at the protein level and that its expression correlates with high Gleason score, pT and pN stages, and biochemical recurrence. RNA interference-mediated siliencing or pharmacologic inhibition of OGT was sufficient to decrease prostate cancer cell growth. Microarray profiling showed that the principal effects of OGT inhibition in prostate cancer cells were related to cell-cycle progression and DNA replication. In particular, c-MYC was identified as a candidate upstream regulator of OGT target genes and OGT inhibition elicited a dose-dependent decrease in the levels of c-MYC protein but not c-MYC mRNA in cell lines. Supporting this relationship, expression of c-MYC and OGT was tightly correlated in human prostate cancer samples (n = 1306). Our findings identify HBP as a modulator of prostate cancer growth and c-MYC as a key target of OGT function in prostate cancer cells.

PIAS1 is increased in human prostate cancer and enhances proliferation through inhibition of p21

Prostate cancer development and progression are associated with alterations in expression and function of elements of cytokine networks, some of which can activate multiple signaling pathways. Protein inhibitor of activated signal transducers and activators of transcription (PIAS)1, a regulator of cytokine signaling, may be implicated in the modulation of cellular events during carcinogenesis. This study was designed to investigate the functional significance of PIAS1 in models of human prostate cancer. We demonstrate for the first time that PIAS1 protein expression is significantly higher in malignant areas of clinical prostate cancer specimens than in normal tissues, thus suggesting a growth-promoting role for PIAS1. Expression of PIAS1 was observed in the majority of tested prostate cancer cell lines. In addition, we investigated the mechanism by which PIAS1 might promote prostate cancer and found that down-regulation of PIAS1 leads to decreased proliferation and colony formation ability of prostate cancer cell lines. This decrease correlates with cell cycle arrest in the G0/G1 phase, which is mediated by increased expression of p21(CIP1/WAF1). Furthermore, PIAS1 overexpression positively influences cell cycle progression and thereby stimulates proliferation, which can be mechanistically explained by a decrease in the levels of cellular p21. Taken together, our data reveal an important new role for PIAS1 in the regulation of cell proliferation in prostate cancer.

Heterogeneity and clinical significance of ETV1 translocations in human prostate cancer

A fluorescence in situ hybridisation (FISH) assay has been used to screen for ETV1 gene rearrangements in a cohort of 429 prostate cancers from patients who had been diagnosed by trans-urethral resection of the prostate. The presence of ETV1 gene alterations (found in 23 cases, 5.4%) was correlated with higher Gleason Score (P=0.001), PSA level at diagnosis (P=<0.0001) and clinical stage (P=0.017) but was not linked to poorer survival. We found that the six previously characterised translocation partners of ETV1 only accounted for 34% of ETV1 re-arrangements (eight out of 23) in this series, with fusion to the androgen-repressed gene C15orf21 representing the commonest event (four out of 23). In 5'-RACE experiments on RNA extracted from formalin-fixed tissue we identified the androgen-upregulated gene ACSL3 as a new 5'-translocation partner of ETV1. These studies report a novel fusion partner for ETV1 and highlight the considerable heterogeneity of ETV1 gene rearrangements in human prostate cancer.

Prognostic role of lemur tyrosine kinase-3 germline polymorphisms in adjuvant gastric cancer in Japan and the United States

Lemur tyrosine kinase-3 (LMTK3) was recently identified as an estrogen receptor (ER)-α modulator related to endocrine therapy resistance, and its polymorphisms rs9989661 (T>C) T/T genotype and rs8108419 (G>A) G/G or A/G genotype predicted improved outcomes in breast cancer. Because different predominant ER distributions link to breast and gastric cancer and little is known of the prognostic role of LMTK3 in gastric cancer, this study was carried out to clarify the prognostic role of these polymorphisms in gastric cancer. One-hundred and sixty-nine Japanese and 137 U.S. patients with localized gastric adenocarcinoma were enrolled. Genomic DNA was extracted from blood or tissue, and all samples were analyzed by PCR-based direct DNA sequencing. Overall, these polymorphisms were not associated with survival in both cohorts. When gender was considered, in multivariate analysis, harboring rs9989661 T/T genotype was associated with disease-free survival [HR, 4.37; 95% confidence interval (CI), 2.08-9.18; P < 0.0001] and overall survival (OS; HR, 3.69; 95% CI, 1.65-8.24; P = 0.0014) in the Japanese males and time to recurrence (HR, 7.29; 95% CI, 1.07-49.80; P = 0.043) in the U.S. females. Meanwhile, harboring rs8108419 G/G genotype was associated with OS in the Japanese females (HR, 3.04; 95% CI, 1.08-8.56; P = 0.035) and the U.S. males (HR, 3.39; 95% CI, 1.31-8.80; P = 0.012). The prognostic role of these polymorphisms may be negative in gastric cancer. These findings suggest that the estrogen pathway may play a prognostic role in patients with gastric cancer but this may be dependent on the regional differences both in physiology and genetic alterations of gastric cancer.

The Early Effects of Rapid Androgen Deprivation on Human Prostate Cancer

The androgen receptor (AR) is the dominant growth factor in prostate cancer (PCa). Therefore, understanding how ARs regulate the human transcriptome is of paramount importance. The early effects of castration on human PCa have not previously been studied 27 patients medically castrated with degarelix 7 d before radical prostatectomy. We used mass spectrometry, immunohistochemistry, and gene expression array (validated by reverse transcription-polymerase chain reaction) to compare resected tumour with matched, controlled, untreated PCa tissue. All patients had levels of serum androgen, with reduced levels of intraprostatic androgen at prostatectomy. We observed differential expression of known androgen-regulated genes (TMPRSS2, KLK3, CAMKK2, FKBP5). We identified 749 genes downregulated and 908 genes upregulated following castration. AR regulation of α-methylacyl-CoA racemase expression and three other genes (FAM129A, RAB27A, and KIAA0101) was confirmed. Upregulation of oestrogen receptor 1 (ESR1) expression was observed in malignant epithelia and was associated with differential expression of ESR1-regulated genes and correlated with proliferation (Ki-67 expression).

PATIENT SUMMARY: This first-in-man study defines the rapid gene expression changes taking place in prostate cancer (PCa) following castration. Expression levels of the genes that the androgen receptor regulates are predictive of treatment outcome. Upregulation of oestrogen receptor 1 is a mechanism by which PCa cells may survive despite castration.

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

Analysis of wntless (WLS) expression in gastric, ovarian, and breast cancers reveals a strong association with HER2 overexpression

The oncogenic role of WNT is well characterized. Wntless (WLS) (also known as GPR177, or Evi), a key modulator of WNT protein secretion, was recently found to be highly overexpressed in malignant astrocytomas. We hypothesized that this molecule may be aberrantly expressed in other cancers known to possess aberrant WNT signaling such as ovarian, gastric, and breast cancers. Immunohistochemical analysis using a TMA platform revealed WLS overexpression in a subset of ovarian, gastric, and breast tumors; this overexpression was associated with poorer clinical outcomes in gastric cancer (P=0.025). In addition, a strong correlation was observed between WLS expression and human epidermal growth factor receptor 2 (HER2) overexpression. Indeed, 100% of HER2-positive intestinal gastric carcinomas, 100% of HER2-positive serous ovarian carcinomas, and 64% of HER2-positive breast carcinomas coexpressed WLS protein. Although HER2 protein expression or gene amplification is an established predictive biomarker for trastuzumab response in breast and gastric cancers, a significant proportion of HER2-positive tumors display resistance to trastuzumab, which may be in part explainable by a possible mechanistic link between WLS and HER2.

BubR1 is required for the mitotic block induced by combretastatin-A4 and a novel cis-restricted ß-lactam analogue in human cancer cells

BubR1 is a well-defined guardian of the mitotic spindle, initiating mitotic arrest in response to the lack of tension and/or chromosome alignment across the mitotic plate. However, the role of BubR1 in combretastatin-induced cell death remains unknown. In this study, we describe the effects of combretastatin A-4 (CA-4) and a synthetic cis-restricted 3,4-diaryl-2-azetidinone (ß-lactam) analogue (CA-432) on the modulation and phosphorylation of BubR1 in human cervical cancer-derived cells. We demonstrate that CA-4 and CA-432 depolymerise the microtubular network of human cervical carcinoma-derived cells. Both compounds induced the disassembly of the microtubules and the loss of microtubule tension led to the early phosphorylation of BubR1 and the late cleavage of BubR1. The phosphorylation of BubR1 correlated with the onset of G2M cell cycle arrest whilst the cleavage of BubR1 coincided with apoptosis induced by the combretastatins. The combretastatin-induced apoptosis and the BubR1 cleavage were caspase-dependent. In vitro enzyme digests demonstrated that combretastatin-activated BubR1 is a substrate for caspase-3. Gene silencing of BubR1 with small interfering RNA severely compromised combretastatin-induced G2M cell cycle arrest with a corresponding increase in the formation of polyploid cells in both cervical and breast cancer-derived cells. In summary, BubR1 is required to maintain the G2M arrest and limit the formation of polyploid cells in response to continued combretastatin exposure. Moreover, substitution of the ethylene bridge with 3,4-diaryl-2-azetidinone did not alter the tubulin depolymerising properties or the subsequent mitotic spindle checkpoint response to CA-4 in human cancer cells.

Nonapical and Cytoplasmic Expression of Interleukin-8, CXCR1, and CXCR2 Correlates with Cell Proliferation and Microvessel Density in Prostate Cancer

Purpose: We characterized interleukin-8 (IL-8) and IL-8 receptor expression (CXCR1 and CXCR2) in prostate cancer to address their significance to this disease. Experimental Design: Immunohistochemistry was conducted on 40 cases of human prostate biopsy containing histologically normal and neoplastic tissue, excised from patients with locally confined or invasive androgen-dependent prostate cancer, and 10 cases of transurethral resection of the prostate material from patients with androgen-independent disease. Results: Weak to moderate IL-8 expression was strictly localized to the apical membrane of normal prostate epithelium. In contrast, membranous expression of IL-8, CXCR1, and CXCR2 was nonapical in cancer cells of Gleason pattern 3 and 4, whereas circumferential expression was present in Gleason pattern 5 and androgen-independent prostate cancer. Each of IL-8, CXCR1, and CXCR2 were also increasingly localized to the cytoplasm of cancer cells in correlation with advancing stage of disease. Cytoplasmic expression (but not apical membrane expression) of IL-8 in Gleason pattern 3 and 4 cancer correlated with Ki-67 expression (R = 0.79; P <0.001), cyclin D1 expression (R = 0.79; P <0.001), and microvessel density (R = 0.81; P <0.001). In vitro studies on androgen-independent PC3 cells confirmed the mitogenic activity of IL-8, increasing the rate of cell proliferation through activation of both CXCR1 and CXCR2 receptors. Conclusions: We propose that the concurrent increase in IL-8 and IL-8 receptor expression in human prostate cancer induces autocrine signaling that may be functionally significant in initiating and promoting the progression of prostate cancer by underpinning cell proliferation and angiogenesis.

Epidermal Growth Factor Receptor Activity Determines Response of Colorectal Cancer Cells to Gefitinib Alone and in Combination with Chemotherapy.

Purpose: Up to now, there have been no established predictive markers for response to epidermal growth factor receptor (EGFR/HER1/erbB1) inhibitors alone and in combination with chemotherapy in colorectal cancer. To identify markers that predict response to EGFR-based chemotherapy regimens, we analyzed the response of human colorectal cancer cell lines to the EGFR-tyrosine kinase inhibitor, gefitinib (Iressa, AstraZeneca, Wilmington, DE), as a single agent and in combination with oxaliplatin and 5-fluorouracil (5-FU). Experimental Design: Cell viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and crystal violet cell viability assays and analyzed by ANOVA. Apoptosis was measured by flow cytometry, poly(ADP-ribose) polymerase, and caspase 3 cleavage. EGFR protein phosphorylation was detected by Western blotting. Results: Cell lines displaying high constitutive EGFR phosphorylation (a surrogate marker for EGFR activity) were more sensitive to gefitinib. Furthermore, in cell lines exhibiting low constitutive EGFR phosphorylation, an antagonistic interaction between gefitinib and oxaliplatin was observed, whereas in cell lines with high basal EGFR phosphorylation, the interaction was synergistic. In addition, oxaliplatin treatment increased EGFR phosphorylation in those cell lines in which oxaliplatin and gefitinib were synergistic but down-regulated EGFR phosphorylation in those lines in which oxaliplatin and gefitinib were antagonistic. In contrast to oxaliplatin, 5-FU treatment increased EGFR phosphorylation in all cell lines and this correlated with synergistic decreases in cell viability when 5-FU was combined with gefitinib. Conclusions: These results suggest that phospho-EGFR levels determine the sensitivity of colorectal cancer cells to gefitinib alone and that chemotherapy-mediated changes in phospho-EGFR levels determine the nature of interaction between gefitinib and chemotherapy.

HIF-1 and NF-kappaB-mediated upregulation of CXCR1 and CXCR2 expression promotes cell survival in hypoxic prostate cancer cells

Hypoxic cancer cells are resistant to treatment, leading to the selection of cells with a more malignant phenotype. The expression of interleukin-8 (IL-8) plays an important role in the tumorigenesis and metastasis of solid tumors including prostate cancer. Recently, we detected elevated expression of IL-8 and IL-8 receptors in human prostate cancer tissue. The objective of the current study was to determine whether hypoxia increases IL-8 and IL-8 receptor expression in prostate cancer cells and whether this contributes to a survival advantage in hypoxic cells. IL-8, CXCR1 and CXCR2 messenger RNA (mRNA) expression in PC3 cells was upregulated in response to hypoxia in a time-dependent manner. Elevated IL-8 secretion following hypoxia was detected by enzyme-linked immunosorbent assay, while immunoblotting confirmed elevated receptor expression. Attenuation of hypoxia-inducible factor (HIF-1) and nuclear factor-kappaB (NF-kappaB) transcriptional activity using small interfering RNA (siRNA), a HIF-1 dominant-negative and pharmacological inhibitors, abrogated hypoxia-induced transcription of CXCR1 and CXCR2 in PC3 cells. Furthermore, chromatin-IP analysis demonstrated binding of HIF-1 and NF-kappaB to CXCR1. Finally, inhibition of IL-8 signaling potentiated etoposide-induced cell death in hypoxic PC3 cells. These results suggest that IL-8 signaling confers a survival advantage to hypoxic prostate cancer cells, and therefore, strategies to inhibit IL-8 signaling may sensitize hypoxic tumor cells to conventional treatments.

Molecular basis for estrogen receptor alpha deficiency in BRCA1-linked breast cancer

Background BRCA1-mutant breast tumors are typically estrogen receptor alpha (ER alpha) negative, whereas most sporadic tumors express wild-type BRCA1 and are ER alpha positive. We examined a possible mechanism for the observed ER alpha-negative phenotype of BRCA1-mutant tumors.

Methods We used a breast cancer disease-specific microarray to identify transcripts that were differentially expressed between paraffin-embedded samples of 17 BRCA1-mutant and 14 sporadic breast tumors. We measured the mRNA levels of estrogen receptor 1 (ESR1) ( the gene encoding ER alpha), which was differentially expressed in the tumor samples, by quantitative polymerase chain reaction. Regulation of ESR1 mRNA and ER alpha protein expression was assessed in human breast cancer HCC1937 cells that were stably reconstituted with wild-type BRCA1 expression construct and in human breast cancer T47D and MCF-7 cells transiently transfected with BRCA1-specific short-interfering RNA ( siRNA). Chromatin immunoprecipitation assays were performed to determine if BRCA1 binds the ESR1 promoter and to identify other interacting proteins. Sensitivity to the antiestrogen drug fulvestrant was examined in T47D and MCF-7 cells transfected with BRCA1-specific siRNA. All statistical tests were two-sided.

Results Mean ESR1 gene expression was 5.4-fold lower in BRCA1-mutant tumors than in sporadic tumors ( 95% confidence interval [CI]=2.6-fold to 40.1-fold, P =.0019). The transcription factor Oct-1 recruited BRCA1 to the ESR1 promoter, and both BRCA1 and Oct-1 were required for ER alpha expression. BRCA1-depleted breast cancer cells expressing exogenous ER alpha were more sensitive to fulvestrant than BRCA1-depleted cells transfected with empty vector ( T47D cells, the mean concentration of fulvestrant that inhibited the growth of 40% of the cells [IC40] for empty vector versus ER alpha: > 10(-5) versus 8.0 x 10(-9) M [ 95% CI=3.1x10(-10) to 3.2 x 10(-6) M]; MCF-7 cells, mean IC40 for empty vector versus ER alpha : > 10(-5) versus 4.9 x 10(-8) M [ 95% CI=2.0 x 10(-9) to 3.9 x 10(-6) M]).

Conclusions BRCA1 alters the response of breast cancer cells to antiestrogen therapy by directly modulating ER alpha expression.

Histone H2AX phosphorylation as a molecular pharmacological marker for DNA interstrand crosslink cancer chemotherapy

The aims of this study were to investigate mechanisms of action involved in H2AX phosphorylation by DNA interstrand crosslinking (ICL) agents and determine whether gamma H2AX could be a suitable pharmacological marker for identifying potential ICL cellular chemosensitivity. In normal human fibroblasts, after treatment with nitrogen mustard (HN2) or cisplatin, the peak gamma H2AX response was detected 2-3 h after the peak of DNA ICLs measured using the comet assay, a validated method for detecting ICLs in vitro or in clinical samples. Detection of gamma H2AX foci by immunofluorescence microscopy could be routinely detected with 6-10 times lower concentrations of both drugs compared to detection of ICLs using the comet assay. A major pathway for repairing DNA ICLs is the initial unhooking of the ICL by the ERCC1-XPF endonuclease followed by homologous recombination. HN2 or cisplatin-induced gamma H2AX foci persisted significantly longer in both, ERCC1 or XRCC3 (homologous recombination) defective Chinese hamster cells that are highly sensitive to cell killing by ICL agents compared to wild type or ionising radiation sensitive XRCC5 cells. An advantage of using gamma H2AX immunofluorescence over the comet assay is that it appears to detect ICL chemosensitivity in both ERCC1 and HR defective cells. With HN2 and cisplatin, gamma H2AX foci also persisted in chemosensitive human ovarian cancer cells (A2780) compared to chemoresistant (A2780cisR) cells. These results show that gamma H2AX can act as a highly sensitive and general marker of DNA damage induced by HN2 or cisplatin and shows promise for predicting potential cellular chemosensitivity to ICL agents. (c) 2008 Elsevier Inc. All rights reserved.