Alexandra Pohl

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.

Gender Disparities in Metastatic Colorectal Cancer Survival

Purpose: Previous studies have shown that estrogen prevents colon cancer in postmenopausal women, indicating a role in colorectal cancer carcinogenesis and tumor progression. We investigated the interactions between sex, age, ethnicity, and year of diagnosis on overall survival (OS) in patients with metastatic colorectal cancer (MCRC). Experimental Design: We screened 52,882 patients with MCRC from 1988 to 2004, using the Surveillance Epidemiology and End Results registry. Age at diagnosis, sex, ethnicity, tumor location, year of diagnosis, OS, and cancer-specific survival were evaluated using Cox proportional hazards model. The models were adjusted for marital status, tumor site, tumor differentiation, and treatment with radiation and/or surgery. Results: We observed that younger women (18-44 years old) with MCRC lived longer than younger men (17 months versus 14; P < 0.0001, log-rank test). In contrast, older women (55 years and older) had significantly worse OS than older men (7 months versus 9; P < 0.0001, log-rank test). In multivariate analysis, we found that gender discrepancies have widened in recent years; young women diagnosed after 2000 have improved cancer-specific survival, compared to men (hazard ratio, 0.778; 95% confidence interval, 0.669-0.904), but those diagnosed before 2000 benefit less (hazard ratio, 0.931; 95% confidence interval, 0.821-1.056). Conclusion: As one of the largest data sets analyzed to establish that younger women with MCRC survive longer than younger men, hormonal status not only seems to play an important role in the development and pathogenesis of colorectal cancer but also may be of prognostic significance. These data warrant further studies to determine the role of estrogen in colorectal cancer. (Clin Cancer Res 2009;15(20):6391–7)

Survival of metastatic gastric cancer: Significance of age, sex and race/ethnicity

BACKGROUND Despite the success of modern chemotherapy in the treatment of large bowel cancers, patients with metastatic gastric cancer continue to have a dismal outcome. Identifying predictive and prognostic markers is an important step to improving current treatment approaches and extending survival. METHODS Extracting data from the US NCIs Surveillance, Epidemiology, and End Results (SEER) registries, we compared overall survival for patients with metastatic gastric cancer by gender, age, and ethnicity using Cox proportional hazards models. 13,840 patients (≥ 18 years) were identified from 1988-2004. Males and females were categorized by age grouping and ethnicity. RESULTS 19% of Hispanic patients were diagnosed < 45 years of age as compared to 5.5% of Caucasians. Caucasian patients and men were more likely to be diagnosed with tumors in the gastric cardia (P<0.001). In our survival analysis, we found that women had a lower risk of dying as compared to men (P<0.001). Overall survival diminished with age (P<0.001). The median overall survival was 6 months in patients of ≤ 44 years old as compared to 3 months in patients 75 years and older. Gender differences in overall survival significantly varied by race and tumor grade/differentiation (P for interaction = 0.003 and 0.005, respectively). CONCLUSION This is the largest study of metastatic gastric cancer patients from the SEER registry to show that age, gender, and tumor location are significant independent prognostic factors for overall survival in patients with metastatic gastric cancer.

Thymidylate synthase gene variations: predictive and prognostic markers

Since its introduction more than 50 years ago by Heidelberger et al., the fluoropyrimidine 5-fluorouracil (5-FU) has remained the mainstay of therapeutic regimens used in the treatment of colorectal cancer and other human malignancies, with single-agent response rates of 20% to 25% in advanced disease stage. Pharmacogenomics has emerged as a useful tool to address interindividual gene variations by analyzing the interplay of host and tumor genotype and drug efficacy and toxicity. Having a reliable panel of prognostic and predictive markers will be critical in selecting an individualized and tailored chemotherapy regimen based on the particular tumor and host genotype. Although conflicting results have been reported, higher thymidylate synthase (TS) protein and mRNA expression levels in tumors have generally been associated with poor clinical outcome in patients treated with 5-FU–based chemotherapy regimens. However, the cause of the variability in TS expression still remains not fully understood, although several germ-line polymorphisms seem to affect the expression of TS, some of which have been found to have an effect on prognosis and the probability of response to 5-FU–based chemotherapy. This review will provide an update on pharmacogenomic studies of TS that were aimed at elucidating their role as prognostic and predictive markers. [Mol Cancer Ther 2009;8(5):1000–7]

Thymidylate Synthase Haplotype is Associated with Tumor Recurrence in Stage II and Stage III Colon Cancer Patients

Background Tumor recurrence after curative resection is a major problem in the management of colon cancer therapy. Identifying molecular markers for tumor recurrence is critical for successfully selecting patients who are more likely to benefit from adjuvant chemotherapy. We analyzed the value of thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms as a prognostic marker in stage II and stage III colon cancer patients treated with 5-fluorouracil-based adjuvant chemotherapy. Methods Between 1987 and 2007, blood samples were obtained from 197 patients with stage II or stage III colon cancer at medical facilities at the University of Southern California. DNA was extracted from peripheral blood, and the genotypes were analyzed using PCR–restriction fragment length polymorphism technique. Results Patients harboring the TS 3RG/+6-bp haplotype were at greatest risk to develop tumor recurrence [relative risk (RR): 2.25; 95% confidence interval (CI): 1.04–4.85; adjusted P value=0.032]. TS enhancer region 3RG alone (RR: 3.48 years; 95% CI: 1.61–7.54; adjusted P value=0.013) or in combination with TS 1494del6 bp (RR: 3.41 years; 95% CI: 1.33–8.75; adjusted P value=0.044) proved to be adverse prognostic markers in both univariate and multivariable analysis. Conclusion ‘High-expression’ variants of TS 2R/3R repeat, TS enhancer region 3R G/C, TS 1494del6 bp, and TS haplotype analysis might help to identify stage II and stage III colon cancer patients who are at great risk of developing tumor recurrence, and also those who are more likely to benefit from 5-fluorouracil-based adjuvant chemotherapy. Larger, independent, prospective studies are, however, needed to confirm and validate our preliminary findings.

Polymorphisms in interleukin 1 beta and interleukin 1 receptor antagonist associated with tumor recurrence in stage Ii colon cancer

Purpose Identifying molecular markers for tumor recurrence is critical in successfully selecting patients with stage II colon cancer who are more likely to benefit from adjuvant chemotherapy. Interleukin 1 beta (IL1B) and interleukin 1 receptor antagonist (IL1RN) have been shown to play a critical role in the early onset of tumor-associated angiogenesis. In this study, we tested whether eight functionally significant polymorphisms within six genes of the angiogenesis pathway [IL1B, IL1RN, vascular endothelial growth factor A (VEGFA), VEGF receptor 2, interleukin-8, cyclooxygenase-2] will predict the risk of tumor recurrence in stage II colon cancer patients treated with 5-fluorouracil based adjuvant chemotherapy. Experimental design Blood samples were obtained from 109 patients with stage II colon cancer at the University of Southern California medical facilities. DNA was extracted from peripheral blood and the genotypes were analyzed using PCR-restriction fragment length polymorphism protocols. Results Patients harboring the IL1RN/IL1B 1-T-C (IL-1RN variable number tandem repeats (VNTR)/IL1B C+3954T/C-511T) haplotype were at greatest risk of developing tumor recurrence [relative risk (RR): 2.72, 95% confidence interval (CI): 1.22–6.08] (adjusted P=0.015). In addition, IL1B +3954 any T (RR: 2.78, 95% CI: 0.99–7.83) (adjusted P=0.043), IL1RN VNTR (RR: 6.09, 95% CI: 1.11–33.4) (adjusted P=0.038), and VEGFA –634 any C (RR: 2.91, 95% CI: 1.13–7.48) (adjusted P=0.026) were shown to be adverse prognostic markers, in both univariate and multivariable analyses. Conclusion Polymorphisms in IL1B, IL1RN, and VEGFA as well as IL1B/IL1RN haplotype analysis may serve as molecular markers for tumor recurrence in stage II colon cancer, indicating that the analysis of angiogenesis-related gene polymorphisms may help to identify patient subgroups 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.

Genetic variations in angiogenesis pathway genes predict tumor recurrence in localized adenocarcinoma of the esophagus.

Objective:The aim of this study was to determine whether the risk of systemic disease after esophagectomy could be predicted by angiogenesis-related gene polymorphisms. Summary Background Data:Systemic tumor recurrence after curative resection continues to impose a significant problem in the management of patients with localized esophageal adenocarcinoma (EA). The identification of molecular markers of prognosis will help to better define tumor stage, indicate disease progression, identify novel therapeutic targets, and monitor response to therapy. Proteinase-activated-receptor 1 (PAR-1) and epidermal growth factor (EGF) have been shown to mediate the regulation of local and early-onset angiogenesis, and in turn may impact the process of tumor growth and disease progression. Methods:We investigated tissue samples from 239 patients with localized EA treated with surgery alone. DNA was isolated from formalin-fixed paraffin-embedded normal esophageal tissue samples and polymorphisms were analyzed using polymerase chain reaction-restriction fragment length polymorphism and 5′-end [&ggr;-33P] ATP-labeled polymerase chain reaction methods. Results:PAR-1 −506 ins/del (adjusted P value = 0.011) and EGF +61 A>G (adjusted P value = 0.035) showed to be adverse prognostic markers, in both univariate and multivariable analyses. In combined analysis, grouping alleles into favorable versus nonfavorable alleles, high expression variants of PAR-1 −506 ins/del (any insertion allele) and EGF +61 A>G (A/A) were associated with a higher likelihood of developing tumor recurrence (adjusted P value <0.001). Conclusion:This study supports the role of functional PAR-1 and EGF polymorphisms as independent prognostic markers in localized EA and may therefore help to identify patient subgroups at high risk for tumor recurrence.

Stem cells in colon cancer.

The concept that cancer might arise from a rare population of cells with stem cell-like properties was proposed 150 years ago. Increasing evidence during the past 2 decades suggests the existence of a small subgroup of cells in cancer that are responsible for tumor growth and proliferation. Stem cells have self-renewing properties; thus, they are appealing candidates for generating the malignant phenotype. Although the concept of stem cells in leukemia has received significant attention for more than the past decade, over the past several years, expression of several surface markers on cancer cells has led to identification of tumor-initiating cells in several solid tumors, including melanoma, brain, breast, prostate, liver, pancreatic, ovarian, and recently, colon cancer. This review will provide an update of the biologic basis of the stem cell model and possible targets for the treatment of colon cancer.

Pharmacogenetic profiling of CD133 is associated with response rate (RR) and progression-free survival (PFS) in patients with metastatic colorectal cancer (mCRC), treated with bevacizumab-based chemotherapy.

Recent studies suggest CD133, a surface protein widely used for isolation of colon cancer stem cells, to be associated with tumor angiogenesis and recurrence. We hypothesized that gene expression levels and germline variations in CD133 will predict clinical outcome in patients with metastatic colorectal cancer (mCRC), treated in first-line setting with 5-fluorouracil, oxaliplatin and bevacizumab (BV), and we investigated whether there is a correlation with gene expression levels of CD133, vascular endothelial growth factor (VEGF) and its receptors. We evaluated intra-tumoral gene expression levels by quantitative real-time (RT) PCR from 54 patients and three germline variants of the CD133 gene by PCR-restriction-fragment length polymorphism from 91 patients with genomic DNA. High gene expression levels of CD133 (>7.76) conferred a significantly greater tumor response (RR=86%) than patients with low expression levels (⩽7.76, RR=38%, adjusted P=0.003), independent of VEGF or its receptor gene expression levels. Gene expression levels of CD133 were significantly associated with VEGF and its receptors messenger RNA levels (VEGFR-1 (P<0.01), -2 and -3, P<0.05). Combined analyses of two polymorphisms showed a significant association with progression-free survival (PFS) (18.5 months vs 9.8 months, P=0.004) in a multivariate analysis as an independent prognostic factor for PFS (adjusted P=0.002). These results suggest that CD133 is a predictive marker for standard first-line BV-based treatment in mCRC.