Adriana Prati

Inhibition of Cell Survival and Invasive Potential of Colorectal Carcinoma Cells by the Tyrosine Kinase Inhibitor STI571

Inhibiting tyrosine kinases has recently emerged as a therapeutic modality in several forms of neoplasia. The tyrosine kinase inhibitor STI571 (IMATINIB MESYLATE; GLEEVEC; GLIVEC) is a case in point as it has shown promise in the treatment of malignancies expressing the BCR/ABL fusion protein. In addition to BCR/ABL, STI571 inhibits the tyrosine kinase moieties of several cell surface receptors including the platelet-derived growth factor (PDGF) receptors and c-Kit. Previous work demonstrated that c-Kit activation supports migration, invasion and, survival of certain colorectal carcinoma cells including DLD-1. Here we describe that blocking c-Kit with STI571 inhibits these malignant traits not only in DLD-1 cells but also in two early passage colorectal carcinoma cell strains. Specifically, STI571 inhibited anchorage-independent colony formation and cell scattering in semi-solid medium. Furthermore, it enhanced apoptosis susceptibility and abrogated invasion of DLD-1 cells through Matrigel. In addition, STI571 treatment affected the balance of the Bcl-2 family of apoptosis regulators on favor of a pro-apoptotic phenotype. Specifically, STI571 treatment of DLD1 cells was associated with lower levels of Bcl-2 expression accompanied by de novo expression of Bcl-xS. Finally, STI571 acted as a chemosensitizing agent in DLD-1 cells when used in combination with 5-fluorouracil.

Ski/SnoN expression in the sequence metaplasia-dysplasia-adenocarcinoma of Barrett's esophagus☆

Barretts esophagus (BE) is a precancerous condition. However, the mechanisms underlying the transformation from metaplastic to dysplastic to adenocarcinomatous epithelium are still poorly understood. As loss of transforming growth factor-beta growth inhibition is considered a hallmark of several human neoplasms, we evaluated the expression of Ski and SnoN (proteins that antagonize transforming growth factor-beta signaling through physical interaction with Smad complex and by recruiting histone deacetylases), as markers of the transforming growth factor-beta signaling pathway, in BE with and without dysplasia. Biopsy samples from 37 patients (26 men, aged 60 +/- 8 years) with histologically proven BE were evaluated; 10 patients had concomitant low-grade dysplasia, 7 high-grade dysplasia (HGD), and 6 HGD associated with adenocarcinoma. Ski and SnoN expression was assessed immunohistochemically. Neither Ski nor SnoN was expressed in normal esophageal epithelium, but both were strongly expressed in BE tissue, with intense cytoplasmic positivity. Expression of these proteins decreased markedly in dysplastic areas in patients with low-grade dysplasia and was absent in those with HGD or HGD/adenocarcinoma. Ski and SnoN proteins are overexpressed in BE and may be involved in abnormal signaling elicited by transforming growth factor-beta in this epithelium, enhancing the tumorigenesis process. These observations might help to elucidate the molecular mechanisms involved in the BE tumorigenesis process.

Comparative evaluation of cancer stem cell markers in normal pancreas and pancreatic ductal adenocarcinoma

Chemoresistance and self-renewal of cancer stem cells (CSC), found in many tumors including pancreatic ductal adenocarcinoma (PDAC), are believed to underlie tumor mass regrowth. The distribution of cells carrying the putative stem-cell markers CD133, Nestin, Notch1-4, Jagged1 and 2, ABCG2 and aldehyde dehydrogenase (ALDH1) was assessed immunohistochemically using PDAC and normal pancreas tissue microarrays. The immunoreactivity was semi-quantitatively graded against the normal pancreas and was correlated with the differentiation grade and disease stage. No statistical significant differences were found between normal pancreas and PDAC in the expression of Nestin, Notch1, 3 and 4, ABCG2 or ALDH1. Notch2 and Jagged1 and 2 expression were increased in PDAC. CD133-positive cells were above-normal in PDAC, but the difference was not statistically significant. Nestin, Notch1-4, Jagged1, ABCG2 and ALDH1 immunostaining scores were not correlated with tumor grade or disease stage. CD133 and Notch2 expression was significantly inversely correlated with tumor grade, but not disease stage. Notch3 immunostaining positively correlated with tumor stage, but not with differentiation grade. Jagged2 protein expression correlated inversely with disease stage, but not with tumor grade. From the clinical standpoint, improved delineation of the tumor CSC signature, putatively responsible for tumor initiation and recurrence after initial response to chemotherapy, may offer novel therapeutic targets for this highly lethal cancer.

Pilot study to relate clinical outcome in pancreatic carcinoma and angiogenic plasma factors/circulating mature/progenitor endothelial cells : Preliminary results

Circulating endothelial cells (CEC) and bone marrow‐derived endothelial progenitors (ECP) play important roles in tumor growth and have been proposed as non‐invasive markers of angiogenesis. However, CEC and ECP levels have not been investigated in pancreatic carcinoma patients. Using four‐color flow cytometry procedures, we evaluated the count of resting (rCEC) and activated (aCEC) endothelial cells and ECP in the peripheral blood of pancreatic carcinoma patients before and after chemotherapy, consisting of gemcitabine (GEM) alone or in combination with oxaliplatin (OX), or with 5‐fluorouracil (5‐FU). We also correlated CEC and ECP levels with plasma levels of relevant angiogenic factors, such as vascular endothelial growth factor (VEGF)‐A, VEGF‐D, angiopoietin (Angio)‐1, and chemokine C‐X‐C motif ligand (CXCL)12, measured by ELISA, and with clinical features of pancreatic cancer. The aCEC, rCEC, ECP, and VEGF‐A plasma levels were significantly higher in locally‐advanced and metastatic patients than controls. Both ECP and VEGF‐A levels correlated positively with disease stage and inversely with patient’s overall survival. Measurements after the treatment course showed that VEGF‐A plasma concentrations and ECP counts had decreased significantly. In particular, VEGF‐A and rCEC were significantly down after treatment with GEM alone or in combination with OX. No significant differences in terms of circulating angiogenic factor or endothelial cell subtype levels were found between responders (patients entering partial remission or with stable disease) and non‐responders (patients with progressive disease). The study provides insights into angiogenesis mechanisms in pancreatic carcinoma, for which anti‐angiogenic targeting of VEGF‐A and ECP could be of interest. (Cancer Sci 2010; 101: 2448–2454)

Human pancreatic carcinoma cells secrete bioactive interleukin-18 after treatment with 5-fluorouracil : Implications for anti-tumor immune response

Recently we observed that pancreatic carcinoma cell lines constitutively express Interleukin-18 (IL-18). Bioactive IL-18 induces Interferon (IFN)-g production, Fas Ligand (FasL) expression, and inhibits angiogenesis, raising the issue of anti-tumor effects of a tumor-derived cytokine and motivating a more detailed analysis of IL-18 production in pancreatic carcinoma cells. This analysis included the study of effects of chemotherapeutic drugs (5-fluorouracil [5-FU], gemcitabine, cisplatin) commonly used in the treatment of pancreatic cancer patients on IL-18 production and processing. IL-18 expression and posttranslational processing were determined using RT-PCR, immunoblot and ELISA in pancreatic carcinoma cell lines and in tumor tissue and serum samples from pancreatic carcinoma patients in the presence and absence of chemotherapeutic drugs. We describe expression of IL-18 in pancreatic carcinoma cells and tissues associated with significantly elevated IL-18 levels in patients sera. Specifically, Capan-2 pancreatic tumor cells produced and secreted precursor IL-18 with no apparent biological activity. However, the chemotherapeutic agent 5-FU, by inducing Caspase-1 and Caspase-3 activation, induced secretion of proteolytically processed mature and degraded IL-18 species, respectively, in Capan-2 cells. Conditioned medium from 5-FU-treated but not control Capan-2 cells induced IFN-g production by activated T cells in an IL-18-dependent manner. Furthermore, adjuvant polychemotherapy including 5-FU significantly increased serum levels of mature, bioactive IL-18 in pancreatic carcinoma patients. Treatment of pancreatic cancer cells with 5-FU induced Caspase-dependent processing of pro-IL18 leading to the secretion of biologically active IL-18. These findings delineate a novel mechanism by which chemotherapeutic agents may modulate local anti-tumor cell-mediated immune responses.

IL-18 Paradox in Pancreatic Carcinoma: Elevated Serum Levels of Free IL-18 are Correlated With Poor Survival

The role of the proinflammatory interleukin (IL)-18 in cancer progression remains controversial; we thus examined the hypothesis that impaired antitumor immune response in pancreatic carcinoma patients is related to elevated levels of its natural inhibitor IL-18 binding protein (BP) and/or to alteration in the IL-18 receptor complex expression and function. IL-18 and IL-18 binding protein isoform a (BPa) was assessed in pancreatic carcinoma patients at various disease stages, and after surgery/chemotherapy; free bioactive IL-18 concentrations were calculated. IL-18 receptor complex expression in lymphocyte subsets was analyzed and signaling function was assessed versus healthy donors. Carcinoma cells exhibited below normal IL-18BPa expression and above normal IL-18 expression. Circulating IL-18BPa and IL-18 were above controls. Unexpectedly, free unbound IL-18 serum levels were correlated with disease severity and poor survival. IL-18BPa levels were unchanged by surgery but free IL-18 levels were elevated. Gemcitabine with 5-fluorouracile or oxaliplatin, but not alone, increased IL-18 and free IL-18 levels statistically significantly, without affecting IL-18BPa. Spontaneous/induced IL-18 receptor α and receptor β expression in peripheral blood lymphocyte subsets from patients with advanced disease were near-normal, although CD4+ and CD8+ cells were fewer in percentage, and fully functional in inducing interferon-γ. IL-18 is proposed as novel adjuvant cancer therapy, but free IL-18 levels are increased in the blood of pancreatic carcinoma patients, despite elevated IL-18BP levels, and are associated with poor survival; this highlights recent experimental insights into the prometastatic and proangiogenic effects of IL-18, and suggests that careful preclinical studies are needed to determine the proper application of IL-18 in cancer therapy.

Transforming Growth Factor-β Binding Receptor Endoglin (CD105) Expression in Esophageal Cancer and in Adjacent Nontumorous Esophagus as Prognostic Predictor of Recurrence

BackgroundWe hypothesized that the potent neovascularization marker endoglin (CD105), by differentially highlighting a subset of microvessels (MV) in esophageal cancer (EC), could provide better prognostic/therapeutic information than the panendothelial marker CD34, which also highlights MV.MethodsEndoglin messenger ribonucleic acid (mRNA) expression in normal, malignant, and adjacent nontumorous esophagus tissue was quantified by real-time reverse-transcription polymerase chain reaction (RT-PCR). Sections of formalin-fixed, paraffin-embedded tissues were analyzed immunohistochemically for CD105 and CD34. MV density was counted following a standard protocol. Circulating soluble endoglin levels were determined in patient and control sera, and compared with clinical outcome.ResultsCD105 mRNA was upregulated by a median factor of 2.89 in ECs versus controls. In 28% of patients, CD105 mRNA was upregulated by a median factor of 2.65 in adjacent non-tumorous versus normal tissue. In tumor tissues, CD105 was stained negatively or positively only in a subset of MV. CD34 always showed positive extensive MV staining. In adjacent nontumorous esophagus, CD105 rarely showed diffuse MV staining, while CD34 stained blood-vessel endothelial cells in all non-neoplastic tissue. CD105 expression was high in residual highly dysplastic Barrett’s-type mucosa associated with some adenocarcinomas. No statistically significant difference in endoglin serum levels appeared between patients and normal subjects. Correlation with clinicopathological data showed higher intra-tumor MV-CD105+ scores at more-advanced clinical stages. High-scoring MV-CD105+ patients had significantly shorter disease-free and overall survival; MV-CD34+ density was not survival related. Diffuse CD105 expression in adjacent nontumorous esophagus predicted poorer disease-free and overall survival.ConclusionsOur findings could help identify EC patients who may benefit from targeted anti-angiogenic therapies.

Pancreatic-carcinoma-cell-derived pro-angiogenic factors can induce endothelial-cell differentiation of a subset of circulating CD34+ progenitors

BackgroundCD34+ progenitor cells comprise both hematopoietic and endothelial progenitor cells. Recent studies suggest that circulating endothelial progenitor cells are recruited into the angiogenic vascular system of several cancers, including pancreatic carcinoma, and that they correlate with clinical progress. However, whether endothelial progenitor cell mobilization occurs in response to cytokine release by tumor cells is still unclear.MethodsThe chemotactic- and/or differentiating-activities of the poorly-differentiated pancreatic carcinoma cell line PT45, and of the immortal H6c7 cell line, a line of near-normal pancreatic duct epithelial cells, on endothelial progenitor cells were investigated in vitro using circulating CD34+ as model.ResultsThe study showed that Vascular Endothelial Growth Factor produced by PT45 cells and, at lesser extent, by H6c7 cells, predominantly chemoattract peripheral blood CD34+ expressing the type 2 relative receptor. Addition of PT45-conditioned medium to CD34+ cells, cultured under conditions supporting myeloid cell development, diverted the differentiation of a subset of these progenitor cells into cells expressing endothelial cell markers, such as CD146, CD105, VE-cadherin and von Willebrand Factor-related antigen. Moreover, these endothelial-like cells formed capillary networks in vitro, chiefly through the release of Angiopoietin-1 by PT45 cells.ConclusionsThe results demonstrate that pancreatic-carcinoma cells potentially attract circulating endothelial progenitor cells to the tumor site, by releasing high levels of pro-angiogenic factors such as Vascular Endothelial Growth Factor and Angiopoietin-1, and may direct the differentiation of these cell subsets of the CD34+ cell population into endothelial cells; the latter cells may become a component of the newly-formed vessels, contributing to angiogenesis-mediated tumor growth and metastasis.

Thymic stromal lymphopoietin in human pancreatic ductal adenocarcinoma: expression and prognostic significance

Thymic stromal lymphopoietin (TSLP) has emerged as an important, but contradictory, player conditioning tumor growth. In certain contexts, by driving T helper (h) 2 responses via tumor-associated OX40 Ligand (OX40L)+ dendritic cells (DCs), TSLP may play a pro-tumorigenic role. The study elucidates the importance of TSPL in pancreatic ductal adenocarcinoma (PDAC), by analyzing: i) TSLP levels in PDAC cell-line supernatants and plasma from patients with locally-advanced/metastatic PDAC, pre- and post-treatment with different chemotherapeutic protocols, in comparison with healthy donors; ii) TSLP and OX40L expression in PDAC and normal pancreatic tissues, by immunohistochemistry; iii) OX40L expression on ex vivo-generated normal DCs in the presence of tumor-derived TSLP, by flow cytometry; iv) clinical relevance in terms of diagnostic and prognostic value and influence on treatment modality and response. Some PDAC cell lines, such as BxPC-3, expressed both TSLP mRNA and protein. Normal DCs, generated ex vivo in the presence of TSLP-rich-cell supernatants, displayed increased expression of OX40L, reduced by the addition of a neutralizing anti-TSLP polyclonal antibody. OX40L+ cells were detected in pancreatic tumor inflammatory infiltrates. Abnormally elevated TSLP levels were detected in situ in tumor cells and, systemically, in locally-advanced/metastatic PDAC patients. Of the chemotherapeutic protocols applied, gemcitabine plus oxaliplatin (GEMOX) significantly increased circulating TSLP levels. Elevated plasma TSLP concentration was associated with shorter overall survival and increased risk of poor outcome. Plasma TSLP measurement successfully discriminated PDAC patients from healthy controls. These data show that TSLP secreted by pancreatic cancer cells may directly impact PDAC biology and patient outcome.

Alcoholic extracts of Epilobium, Urtica dioica and Evernia prunastri with 5-fluorouracil in controlling murine colon carcinoma cell growth in vitro

In recent years, there has been growing interest in plant-derived products for their bioactive properties., Results and Conclusion. This study aimed to verify the effect of an herbal-food supplement, comprising alcoholic extracts of Epilobium, Urtica dioica and Evernia prunastri (YATROS, Etnopharma, Turin, Italy), alone or in combination with 5-Fluorouracil, on cell growth, DNA synthesis, cell-cycle profile, cytoskeleton reorganization and E-cadherin protein expression, in the murine colon carcinoma cell line C26. Assays used were respectively the Neutral Red uptake assay, median effect analysis, tritiated thymidine incorporation, flow cytometry, Phalloidin staining, and immunohistochemistry. A chemical fingerprint and multidimensional HPLC-UV-HRMS analysis was also performed on the herbal-food supplements. Intriguingly, a substantial synergistic inhibitory effects on cell growth, DNA synthetic activity and percentage of cells in S phase were noticed when YATROS was combined with 5-Fluorouracil, reducing both dose and timing of exposure of C26 cells to the drug. Moreover, by inducing cytoskeleton reorganization and E-cadherin expression, YATROS can interfere with tumor cell invasiveness. These indications of an agonistic interaction between YATROS and 5-Fluorouracil in colon carcinoma cells may be of interest for clinical applications, and thus merit further investigation.