Philipp C. Manegold

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.

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]

A coactivator role of CARM1 in the dysregulation of β-catenin activity in colorectal cancer cell growth and gene expression

Aberrant activation of Wnt/β-catenin signaling, resulting in the expression of Wnt-regulated oncogenes, is recognized as a critical factor in the etiology of colorectal cancer. Occupancy of β-catenin at promoters of Wnt target genes drives transcription, but the mechanism of β-catenin action remains poorly understood. Here, we show that CARM1 (coactivator-associated arginine methyltransferase 1) interacts with β-catenin and positively modulates β-catenin–mediated gene expression. In colorectal cancer cells with constitutively high Wnt/β-catenin activity, depletion of CARM1 inhibits expression of endogenous Wnt/β-catenin target genes and suppresses clonal survival and anchorage-independent growth. We also identified a colorectal cancer cell line (RKO) with a low basal level of β-catenin, which is dramatically elevated by treatment with Wnt3a. Wnt3a also increased the expression of a subset of endogenous Wnt target genes, and CARM1 was required for the Wnt-induced expression of these target genes and the accompanying dimethylation of arginine 17 of histone H3. Depletion of β-catenin from RKO cells diminished the Wnt-induced occupancy of CARM1 on a Wnt target gene, indicating that CARM1 is recruited to Wnt target genes through its interaction with β-catenin and contributes to transcriptional activation by mediating events (including histone H3 methylation) that are downstream from the actions of β-catenin. Therefore, CARM1 is an important positive modulator of Wnt/β-catenin transcription and neoplastic transformation, and may thereby represent a novel target for therapeutic intervention in cancers involving aberrantly activated Wnt/β-catenin signaling. Mol Cancer Res; 9(5); 660–70. ©2011 AACR.

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.

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 μM; 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.

Pharmacogenomics and -genetics in colorectal cancer.

Despite recent progress in our knowledge about the development and therapy of colorectal cancer (CRC), it still remains one of the major cancer related deaths throughout the world. With the introduction of new cytotoxic and targeting agents a significant improvement in progression-free and overall survival has been achieved. However, a significant percentage (40-50%) of patients do not experience beneficial effects and suffer from severe toxicities. It will be critical to identify molecular markers, which may help to assess therapeutic response and outcome in CRC. Validation of predictive and prognostic molecular markers will enable oncologists to tailor patient specific treatment strategies for the individual patient according to the molecular profile of both the patient and their tumor. Individualized therapy will help to improve therapeutic efficacy and to minimize toxicities and therapeutic expenses.

Wnt Signaling in Stem Cells

Wnt signaling pathways play divergent roles during development, normal homeostasis and disease. Wnt signaling is also critically important in stem cell biology. It has been demonstrated to be involved in both the proliferation and differentiation of stem and progenitor populations. Wnt/β-catenin signaling also plays a critical role in lineage decision/commitment. These dramatically different outcomes upon activation of the Wnt signaling cascade has fueled enormous controversy concerning the role of Wnt signaling in maintenance of potency and induction of differentiation. Tight regulation and controlled coordination of the Wnt signaling cascade is required to maintain the balance between proliferation and differentiation. The diverse and titrated responses that result from the activation of the Wnt signaling pathway however begs the question of how the Wnt signaling network integrates the various inputs that a cell receives to elicit the correct and coordinated responses.

Can we predict the response to epidermal growth factor receptor targeted therapy

Epidermal growth factor receptor (EGFR) targeted therapy interferes with a molecular pathway that significantly regulates tumor growth, progression, and survival. Several clinical trials on EGFR targeted therapy revealed objective responses, and also improved survival in patients with different solid tumors. However, considerable differences in therapeutic efficacy were recognized across patient populations that might rely on specific characteristics of the individual patient, the tumor dependence on the EGFR pathway or alternative signaling pathways. Therefore, molecular markers that predict responsiveness to the specific targeted therapy are essential. Predictive markers will help to identify which individual patients might benefit the most from targeted therapy, and thus will help to increase efficacy and decrease toxicities. The occurrence of an acne-like skin rash was the first clinical surrogate marker in EGFR targeted therapy significantly associated with response rate. In gastrointestinal cancer patients promising predictive molecular markers have now been identified within the EGFR signaling pathway. K-ras mutations are associated with resistance to EGFR monoclonal antibodies (mAbs) in metastatic colorectal cancer patients. Moreover, high gene expression levels of EGFR ligands amphiregulin and epiregulin are indicative for improved progression-free survival (PFS) in response to EGFR targeted therapy. Favorable response to EGFR targeted therapy has been correlated with low gene expression levels of vascular endothelial growth factor (VEGF). Furthermore, germline polymorphisms within the genes of epidermal growth factor (EGF) and EGFR, cyclooxygenase-2 (Cox-2), cyclin D1, and FCGR2A/3A are of predictive value. However, these first encouraging findings are limited mostly due to the small patient numbers evaluated in retrospective studies. Thus, large prospective clinical trials are needed to validate these data.

Differentiation Therapy Targeting the β-Catenin/CBP Interaction in Pancreatic Cancer

Background: Although canonical Wnt signaling is known to promote tumorigenesis in pancreatic ductal adenocarcinoma (PDAC), a cancer driven principally by mutant K-Ras, the detailed molecular mechanisms by which the Wnt effector β-catenin regulates such tumorigenesis are largely unknown. We have previously demonstrated that β-catenin’s differential usage of the Kat3 transcriptional coactivator cyclic AMP-response element binding protein-binding protein (CBP) over its highly homologous coactivator p300 increases self-renewal and suppresses differentiation in other types of cancer. Aim/methods: To investigate Wnt-mediated carcinogenesis in PDAC, we have used the specific small molecule CBP/β-catenin antagonist, ICG-001, which our lab identified and has extensively characterized, to examine its effects in human pancreatic cancer cells and in both an orthotopic mouse model and a human patient-derived xenograft (PDX) model of PDAC. Results/conclusion: We report for the first time that K-Ras activation increases the CBP/β-catenin interaction in pancreatic cancer; and that ICG-001 specific antagonism of the CBP/β-catenin interaction sensitizes pancreatic cancer cells and tumors to gemcitabine treatment. These effects were associated with increases in the expression of let-7a microRNA; suppression of K-Ras and survivin; and the elimination of drug-resistant cancer stem/tumor-initiating cells.

Abstract 5772: Antagonizing the CREB binding protein (CBP)/beta-catenin interaction sensitizes pancreatic cancer cells to chemotherapy

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Wnt/beta-catenin signaling plays an important role in the regulation of cell proliferation and differentiation, maintenance of stem cell pluripotency and cancer development. Using specific small molecular inhibitors, we have previously demonstrated that the critical mechanism differentiating between cell proliferation and cell differentiation is the switch of beta-catenin binding to the coactivator CBP or p300 respectively. In colorectal cancer, and hematologic malignancies with overt wnt/beta-catenin signaling activity, the small molecular inhibitor of CBP/beta-catenin enhances sensitivity to chemotherapy and tumor growth control. Although pancreatic cancers do not generally carry mutations in Wnt signaling regulators (e.g. APC, beta-catenin), recent studies indicate that Wnt/beta-catenin signaling promotes tumorigenesis in pancreatic cancer as well. Since pancreatic cancer is one of the most intrinsically resistant cancers to chemotherapy, the purpose of this study was to explore the effect of the small molecular CBP/beta-catenin inhibitor alone and in combination with standard chemotherapy in pancreatic cancer cell lines in vitro and in vivo. The combination of the small molecular inhibitor of CBP/beta-catenin with Gemcitabine or Erlotinib significantly inhibited cell proliferation of Panc-1, BxPC-3 and AsPC-1 pancreatic cancer cells in vitro. Anti-proliferative effects were seen with the combination of a small molecular CBP/beta-catenin antagonist and Gemcitabine concentrations as low as 1nM. qRT-PCR revealed a significant down regulation of the Wnt target genes Survivin and S100A4 which have been shown previously to be of prognostic relevance in pancreatic cancer patients. AsPC-1-Luc pancreatic cancer cells with stable transfected luciferase activity were implanted orthotopically into the pancreas of Nu/Nu mice and mice were randomized to either treatment with single agent small molecular CBP/beta-catenin inhibitor, Gemicitabine, Erlotinib or the combination of small molecular inhibitor and Gemcitabine or Erlotinib. Tumor engraftment and tumor growth were monitored once per week using the bioluminescence imaging system IVIS200. The data of the ongoing orthotopic tumor xenograft study show a beneficial therapeutic effect of the small molecular inhibitor in combination with chemotherapeutic and targeted agents. The results of our study indicate that the Wnt/beta-catenin pathway is an attractive therapeutic target in pancreatic cancer. In particular the inhibition of CBP/beta-catenin interaction using a small molecular inhibitor sensitizes pancreatic cancer cells to the chemotherapeutic agent Gemcitabine and EGFR-targeted therapy with Erlotinib in vitro. Ongoing in vivo experiments appear to be highly promising to confirm the in vitro results. 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 5772.