Simona Tavolari

IL-6 triggers malignant features in mammospheres from human ductal breast carcinoma and normal mammary gland

High serum levels of IL-6 correlate with poor outcome in breast cancer patients. However, no data are available on the relationship between IL-6 and mammary stem/progenitor cells, which may fuel the genesis of breast cancer in vivo. Herein, we address this issue in the MCF-7 breast cancer cell line and in primary human mammospheres (MS), multicellular structures enriched in stem/progenitor cells of the mammary gland. MS from node invasive breast carcinoma tissues expressed IL-6 mRNA at higher levels than did MS from matched non-neoplastic mammary glands. In addition, IL-6 mRNA was detected only in basal-like breast carcinoma tissues, an aggressive breast carcinoma variant showing stem cell features. IL-6 treatment triggered Notch-3-dependent upregulation of the Notch ligand Jagged-1 and promotion of MS and MCF-7-derived spheroid growth. Moreover, IL-6 induced Notch-3-dependent upregulation of the carbonic anhydrase IX gene and promoted a hypoxia-resistant/invasive phenotype in MCF-7 cells and MS. Finally, autocrine IL-6 signaling relied upon Notch-3 activity to sustain the aggressive features of MCF-7-derived hypoxia-selected cells. In conclusion, these data support the hypothesis that IL-6 induces malignant features in Notch-3-expressing stem/progenitor cells from human ductal breast carcinoma and normal mammary gland.

MiR-122/cyclin G1 interaction modulates p53 activity and affects doxorubicin sensitivity of human hepatocarcinoma cells

The identification of target genes is a key step for assessing the role of aberrantly expressed microRNAs (miRNA) in human cancer and for the further development of miRNA-based gene therapy. MiR-122 is a liver-specific miRNA accounting for 70% of the total miRNA population. Its down-regulation is a common feature of both human and mouse hepatocellular carcinoma (HCC). We have previously shown that miR-122 can regulate the expression of cyclin G1, whose high levels have been reported in several human cancers. We evaluated the role of miR-122 and cyclin G1 expression in hepatocarcinogenesis and in response to treatment with doxorubicin and their relevance on survival and time to recurrence (TTR) of HCC patients. We proved that, by modulating cyclin G1, miR-122 influences p53 protein stability and transcriptional activity and reduces invasion capability of HCC-derived cell lines. In addition, in a therapeutic perspective, we assayed the effects of a restored miR-122 expression in triggering doxorubicin-induced apoptosis and we proved that miR-122, as well as cyclin G1 silencing, increases sensitivity to doxorubicin challenge. In patients resected for HCC, lower miR-122 levels were associated with a shorter TTR, whereas higher cyclin G1 expression was related to a lower survival, suggesting that miR-122 might represent an effective molecular target for HCC. Our findings establish a basis toward the development of combined chemo- and miRNA-based therapy for HCC treatment.

Fibroblasts Isolated from Common Sites of Breast Cancer Metastasis Enhance Cancer Cell Growth Rates and Invasiveness in an Interleukin-6–Dependent Manner

Common sites of breast cancer metastasis include the lung, liver, and bone, and of these secondary metastatic sites, estrogen receptor alpha (ERalpha)-positive breast cancer often favors bone. Within secondary organs, cancer cells would predictably encounter tissue-specific fibroblasts or their soluble factors, yet our understanding of how tissue-specific fibroblasts directly affect cancer cell growth rates and survival remains largely unknown. Therefore, we tested the hypothesis that mesenchymal fibroblasts isolated from common sites of breast cancer metastasis provide a more favorable microenvironment with respect to tumor growth rates. We found a direct correlation between the ability of breast, lung, and bone fibroblasts to enhance ERalpha-positive breast cancer cell growth and the level of soluble interleukin-6 (IL-6) produced by each organ-specific fibroblast, and fibroblast-mediated growth enhancement was inhibited by the removal or inhibition of IL-6. Interestingly, mice coinjected with MCF-7 breast tumor cells and senescent skin fibroblasts, which secrete IL-6, developed tumors, whereas mice coinjected with presenescent skin fibroblasts that produce little to no IL-6 failed to form xenograft tumors. We subsequently determined that IL-6 promoted growth and invasion of breast cancer cells through signal transducer and activator of transcription 3-dependent up-regulation of Notch-3, Jagged-1, and carbonic anhydrase IX. These data suggest that tissue-specific fibroblasts and the factors they produce can promote breast cancer disease progression and may represent attractive targets for development of new therapeutics.

The basal-like breast carcinoma phenotype is regulated by SLUG gene expression.

Basal‐like breast carcinoma is an aggressive form of breast cancer, characterized by the absence of oestrogen receptor and HER2 expression, the presence of cytokeratin 5 and epidermal growth factor receptor expression, and by the up‐regulation of stem cell regulatory genes. We show here that tumour tissues expressing high levels of SLUG mRNA show a basal‐like breast carcinoma phenotype and that such tumours also express high levels of stem cell‐regulatory genes, ie CD133, Bmi1. Further, we show that stem/progenitor cells, isolated from ductal breast carcinoma and from normal mammary gland as mammospheres, express SLUG, CD133, and Bmi1 mRNA and show a phenotype similar to that of basal‐like breast carcinoma. We also report that SLUG expression in tumour tissues correlates with that of the hypoxia survival gene carbonic anhydrase IX. In this regard, we report that the exposure of SLUG‐negative/luminal‐like MCF‐7 cells to a hypoxic environment promotes the onset of the basal‐like breast carcinoma phenotype, together with up‐regulation of the SLUG gene, which in turn blunts oestrogen receptor‐α and boosts carbonic anhydrase IX gene expression. Finally, we show that SLUG expression promotes the invasiveness of MCF‐7 cells exposed to hypoxia and sustains the in vivo aggressiveness of hypoxia‐selected, MCF‐7‐derived cells in xenografts. These data indicate that SLUG gene expression is part of a hypoxia‐induced genetic programme which sets up a basal/stem cell‐like, aggressive phenotype in breast cancer cells. Copyright

TNFalpha up-regulates SLUG via the NF-kappaB/HIF1alpha axis, which imparts breast cancer cells with a stem cell-like phenotype

Extracellular and intracellular mediators of inflammation, such as tumor necrosis factor alpha (TNFα) and NF‐kappaB (NF‐κB), play major roles in breast cancer pathogenesis, progression and relapse. SLUG, a mediator of the epithelial–mesenchymal transition process, is over‐expressed in CD44+/CD24− tumor initiating breast cancer cells and in basal‐like carcinoma, a subtype of aggressive breast cancer endowed with a stem cell‐like gene expression profile. Cancer stem cells also over‐express members of the pro‐inflammatory NF‐κB network, but their functional relationship with SLUG expression in breast cancer cells remains unclear. Here, we show that TNFα treatment of human breast cancer cells up‐regulates SLUG with a dependency on canonical NF‐κB/HIF1α signaling, which is strongly enhanced by p53 inactivation. Moreover, SLUG up‐regulation engenders breast cancer cells with stem cell‐like properties including enhanced expression of CD44 and Jagged‐1 in conjunction with estrogen receptor alpha down‐regulation, growth as mammospheres, and extracellular matrix invasiveness. Our results reveal a molecular mechanism whereby TNFα, a major pro‐inflammatory cytokine, imparts breast cancer cells with stem cell‐like features, which are connected to increased tumor aggressiveness. J. Cell. Physiol. 225: 682–691, 2010.

The decrease of cell membrane fluidity by the non-steroidal anti-inflammatory drug Licofelone inhibits epidermal growth factor receptor signalling and triggers apoptosis in HCA-7 colon cancer cells

The ability to induce changes in cell membrane properties is nowadays considered an additional mechanism to explain the pharmacological effects of non-steroidal anti-inflammatory drugs (NSAIDs). We previously demonstrated that the NSAID Licofelone, a dual cyclooxygenase/5-lipoxygenase inhibitor, triggers apoptosis in HCA-7 colon cancer cells independently from the inhibition of these enzymes. Here, we provide evidence that, in HCA-7 cells, the pro-apoptotic effect of this drug relies, at least in part, on its ability to inhibit epidermal growth factor receptor (EGFR) signalling by a decrease of cell membrane fluidity. Indeed, Licofelone induced a relevant change in the relative proportions of some saturated, monounsaturated and polyunsaturated fatty acids constituting HCA-7 phospholipid fraction and significantly increased the levels of cholesterol in HCA-7 cell membrane. All of these changes resulted in a remarkable decrease of membrane fluidity. Such phenomenon was associated with the block of EGFR kinase activity and of its downstream targets, the p44-42 mitogen-activated protein kinase (MAPK) and AKT cascades, whose inhibitions were found to induce apoptosis in HCA-7 cells. Overall, these findings provide a new additional mechanism by which NSAIDs are effective toward colon cancer cells.

Antitumoral Efficacy of the Protease Inhibitor Gabexate Mesilate in Colon Cancer Cells Harbouring KRAS, BRAF and PIK3CA Mutations

The employment of anti-epidermal growth factor receptor (EGFR) antibodies represents a backbone of the therapeutic options for the treatment of metastatic colorectal cancer (mCRC). However, this therapy is poorly effective or ineffective in unselected patients. Mutations in KRAS, BRAF and PIK3CA genes have recently emerged as the best predictive factors of low/absent response to EGFR-targeted therapy. Due to the need for efficacious treatment options for mCRC patients bearing these mutations, in this short report we examined the antitumoral activity of the protease inhibitor gabexate mesilate, alone and in combination with the anti-EGFR monoclonal antibody cetuximab, in a panel of human CRC cell lines harbouring a different expression pattern of wild-type/mutated KRAS, BRAF and PIK3CA genes. Results obtained showed that gabexate mesilate significantly inhibited the growth, invasive potential and tumour-induced angiogenesis in all the CRC cells employed in this study (including those ones harbouring dual KRAS/PIK3CA or BRAF/PIK3CA mutation), while cetuximab affected these parameters only in CRC cells with KRAS, BRAF and PIK3CA wild-type. Notably, the antitumoral efficacy of gabexate mesilate and cetuximab in combination was found to be not superior than that observed with gabexate mesilate as single agent. Overall, these preliminary findings suggest that gabexate mesilate could represent a promising therapeutic option for mCRC patients, particularly for those harbouring KRAS, BRAF and PIK3CA mutations, either as mono-therapy or in addition to standard chemotherapy regimens. Further studies to better elucidate gabexate mesilate mechanism of action in CRC cells are therefore warranted.

Simple and Dendritic Cyclam Derivatives. Photophysical Properties, Effect of Protonation and Zn2+ Coordination, Preliminary Screening as Inhibitors of Tumour Cell Growth

We have synthesized two novel dendrimers (BG1 and BG2) consisting of a 1,4,8,11-tetraazacyclotetradecane (cyclam, 1) core with appended four dimethoxybenzene and eight benzyl units (BG1) and twelve dimethoxybenzene and sixteen benzyl units (BG2). The absorption and luminescence spectra of these compounds and the changes taking place upon protonation and Zn2+ coordination of their cyclam core have been investigated in acetonitrile-dichloromethane 1:1 v/v solution. For comparison purposes, the absorption and luminescence spectra of 1,4,8,11-tetrabenzyl-cyclam (2), and dendrons BD1 and BD2, model compounds of the branches of BG1 and BG2 respectively, have also been studied. BD1, BD2, BG1, and BG2 exhibit the absorption and emission spectra of their 1,3-dimethoxybenzene unit, but in the two dendrimers the emission intensity is quenched by the cyclam amine groups and increases upon protonation and metal coordination. In order to test if these cyclam derivatives have an antitumour effect, we have studied their action on proliferation in the human neuroblastoma TS12 cell line. Screening experiments have shown that cell proliferation was (i) strongly reduced by the tetrabenzyl substituted cyclam 2, and (ii) unaffected by cyclam and the benzo dendrimers BG1 and BG2. Antitumour screening experiments have also been performed on the tetranaphthyl substituted cyclam 3 and the naphtho-dendrimer NG2, whose photophysical properties have been previously studied. Cell proliferation came out to be moderately reduced by 3, whereas dendrimer NG2 had no effect, similar to dendrimers BG1 and BG2.

Molecular and proteomic insight into Notch1 characterization in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) ranks fifth in frequency worldwide amongst all human cancers causing one million deaths annually. Despite many promising treatment options, long-term prognosis remains dismal for the majority of patients who develop recurrence or present with advanced disease. Notch signaling is an evolutionarily conserved pathway crucial for the development and homeostasis of many organs including liver. Herein we showed that aberrant Notch1 is linked to HCC development, tumor recurrence and invasion, which might be mediated, at least in part, through the Notch1-E-Cadherin pathway. Collectively, these findings suggest that targeting Notch1 has important therapeutic value in hepatocellular carcinoma. In this regard, comparative analysis of the secretome of HepG2 and HepG2 Notch1 depleted cells identified novel secreted proteins related to Notch1 expression. Soluble E-Cadherin (sE-Cad) and Thrombospondin-1 (Thbs1) were further validated in human serum as potential biomarkers to predict response to Notch1 inhibitors for a tailored individualized therapy.

Membrane Localization of Human Equilibrative Nucleoside Transporter 1 in Tumor Cells May Predict Response to Adjuvant Gemcitabine in Resected Cholangiocarcinoma Patients

BACKGROUND The use of gemcitabine as an adjuvant modality for cholangiocarcinoma (CC) is increasing, but limited data are available on predictive biomarkers of response. Human equilibrative nucleoside transporter 1 (hENT-1) is the major transporter involved in gemcitabine intracellular uptake. This study investigated the putative predictive role of hENT-1 localization in tumor cells of CC patients undergoing treatment with adjuvant gemcitabine. METHODS Seventy-one consecutive patients with resected CC receiving adjuvant gemcitabine at our center were retrospectively analyzed by immunohistochemistry for hENT-1 localization in tumor cells. The main outcome measure was disease-free survival (DFS). Hazard ratios (HRs) of relapse and associated 95% confidence intervals (CIs) were obtained from proportional hazards regression models stratified on quintiles of propensity score. RESULTS Twenty-three (32.4%) cases were negative for hENT-1, 22 (31.0%) were positive in the cytoplasm only, and 26 (36.6%) showed concomitant cytoplasm/membrane staining. Patients with membrane hENT-1 had a longer DFS (HR 0.49, 95% CI 0.24-0.99, p = .046) than those who were negative or positive only in the cytoplasm of tumor cells. Notably, the association between DFS and membrane hENT-1 was dependent on the number of gemcitabine cycles (one to two cycles: HR 0.96, 95% CI 0.34-2.68; three to four cycles: HR 0.99, 95% CI 0.34-2.90; five to six cycles: HR 0.27, 95% CI 0.10-0.77). CONCLUSION hENT-1 localization on tumor cell membrane may predict response to adjuvant gemcitabine in CC patients receiving more than four cycles of chemotherapy. Further prospective randomized trials on larger populations are required to confirm these preliminary results, so that optimal gemcitabine-based chemotherapy may be tailored for CC patients in the adjuvant setting. IMPLICATIONS FOR PRACTICE Gemcitabine is becoming an increasingly used adjuvant modality in cholangiocarcinoma (CC), but limited data are available on predictive biomarkers of response. In this study, patients receiving more than four cycles of adjuvant gemcitabine and harboring Human equilibrative nucleoside transporter 1 (hENT-1, the major transporter involved in gemcitabine intracellular uptake) on tumor cell membrane had a longer disease-free survival compared with patients negative or positive for hENT-1 only in the cytoplasm of tumor cells. Overall these results may lay the basis for further prospective randomized trials based on a larger population of patients and may prove useful for tailoring appropriate gemcitabine-based chemotherapy for CC patients in the adjuvant setting.