Gianluca Storci

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.

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.

p66Shc/Notch-3 interplay controls self-renewal and hypoxia survival in human stem/progenitor cells of the mammary gland expanded in vitro as mammospheres.

The comprehension of the basic biology of stem cells is expected to provide a useful insight into the pathogenesis of cancer. In particular, there is evidence that hypoxia promotes stem cell renewal in vitro as well as in vivo. It therefore seems reasonable that stem cell survival and hypoxia response are strictly connected at molecular level. We here report that the 66‐kDa isoform of the SHC gene (p66Shc) is induced in a breast cancer cell line by the exposure to hypoxic environment and that it controls the expression of the stem cell regulatory gene Notch‐3. Then, we show that p66Shc/Notch‐3 interplay modulates self‐renewal (by inducing the Notch‐ligand Jagged‐1) and hypoxia survival (by inducing the hypoxia‐survival gene carbonic anhydrase IX) in mammary gland stem/progenitor cells, expanded in vitro as multicellular spheroids (mammospheres). We conclude that mechanisms that regulate stem cell renewal and hypoxia survival are integrated at the level of the p66Shc/Notch3 interplay. Because Notch‐3, Jagged‐1, and carbonic anhydrase IX are dysregulated in breast cancer, and because p66Shc is an aging‐regulating gene, we envision that these data may help in understanding the relationship among aging, cancer, and stem cells.

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

Thoracic aortas from multiorgan donors are suitable for obtaining resident angiogenic mesenchymal stromal cells.

The clinical use of endothelial progenitor cells is hampered by difficulties in obtaining an adequate number of functional progenitors. This study aimed to establish whether human thoracic aortas harvested from healthy multiorgan donors can be a valuable source of angiogenic progenitors. Immunohistochemical tissue studies showed that two distinct cell populations with putative stem cell capabilities, one composed of CD34+ cells and the other of c‐kit+ cells, are present in between the media and adventitia of human thoracic aortas. Ki‐67+ cells with high growth potential were located in an area corresponding to the site of CD34+ and c‐kit+ cell residence. We thus isolated cells (0.5 ∼ 2.0 × 104 aortic progenitors per 25 cm2) which, upon culturing, coexpressed molecules of mesenchymal stromal cells (i.e., CD44+, CD90+, CD105+) and showed a transcript expression of stem cell markers (e.g., OCT4, c‐kit, BCRP‐1, Interleukin‐6) and BMI‐1. Cell expansion was adequate for use in a clinical setting. A subset of cultured cells acquired the phenotype of endothelial cells in the presence of vascular endothelial growth factor (e.g., increased expression of KDR and von Willebrand factor positivity), as documented by flow cytometry, immunofluorescence, electron microscopy, and reverse transcription‐polymerase chain reaction assays. An in vitro angiogenesis test kit revealed that cells were able to form capillary‐like structures within 6 hours of seeding. This study demonstrates that thoracic aortas from multiorgan donors yield mesenchymal stromal cells with the ability to differentiate in vitro into endothelial cells. These cells can be used for the creation of an allogenic bank of angiogenic progenitors, thus providing new options for restoring vascularization at ischemic sites.

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 different apoptotic potential of the p53 codon 72 alleles increases with age and modulates in vivo ischaemia-induced cell death

AbstractA common arginine to proline polymorphism is harboured at codon 72 of the human p53 gene. In this investigation, we found that fibroblasts and lymphocytes isolated from arginine allele homozygote centenarians and sexagenarians (Arg+) undergo an oxidative-stress-induced apoptosis at a higher extent than cells obtained from proline allele carriers (Pro+). At variance, the difference in apoptosis susceptibility between Arg+ and Pro+ is not significant when cells from 30-year-old people are studied. Further, we found that Arg+ and Pro+ cells from centenarians differ in the constitutive levels of p53 protein and p53/MDM2 complex, as well as in the levels of oxidative stress-induced p53/Bcl-xL complex and mitochondria-localised p53. Consistently, all these differences are less evident in cells from 30-year-old people. Finally, we investigated the in vivo functional relevance of the p53 codon 72 genotype in a group of old patients (66–99 years of age) affected by acute myocardial ischaemia, a clinical condition in which in vivo cell death occurs. We found that Arg+ patients show increased levels of Troponin I and CK-MB, two serum markers that correlate with the extent of the ischaemic damage in comparison to Pro+ patients. In conclusion, these data suggest that p53 codon 72 polymorphism contributes to a genetically determined variability in apoptotic susceptibility among old people, which has a potentially relevant role in the context of an age-related pathologic condition, such as myocardial ischaemia.

Novel Dyskerin-Mediated Mechanism of p53 Inactivation through Defective mRNA Translation

In up to 60% of human cancers, p53 gene mutations are responsible for direct inactivation of the tumor suppressor function of p53. Alternative mechanisms of p53 inactivation described thus far mainly affect its posttranslational regulation. In X-linked dyskeratosis congenita, a multisystemic syndrome characterized by increased cancer susceptibility, mutations of the DKC1 gene encoding dyskerin cause a selective defect in the translation of a subgroup of internal ribosome entry site (IRES)-containing cellular mRNAs. In this study, we show that impairment of dyskerin function can cause p53 inactivation due to a defect in p53 mRNA translation. siRNA-mediated reduction of dyskerin levels caused a decrease of p53 mRNA translation, protein levels, and functional activity, both in human breast cancer cells and in primary mammary epithelial progenitor cells. These effects seemed to be independent of the known role of dyskerin in telomerase function, and they were associated with a specific impairment of translation initiation mediated by IRES elements present in p53 mRNA. In a series of human primary breast cancers retaining wild-type p53, we found that low levels of dyskerin expression were associated with reduced expression of p53-positive target genes. Our findings suggest that a dyskerin-mediated mechanism of p53 inactivation may occur in a subset of human tumors.

p53 codon 72 alleles influence the response to anticancer drugs in cells from aged people by regulating the cell cycle inhibitor p21WAF1

A common polymorphism at codon 72 in p53 gene leads to an arginine to proline aminoacidic substitution which affects in an age-dependent manner the susceptibility of cells to undergo apoptosis after oxidative stress. Here we report that dermal fibroblasts from Proline allele carriers (Pro+) display a higher expression of p21WAF1 gene, in both basal conditions and after treatment with doxorubicin and camptothecin. This phenomenon is accompanied by a lower susceptibility of Pro+ cells to undergo apoptosis, a lower capability to over cross G1-S transition and an increased propensity to express markers of cell senescence, with respect to fibroblasts from Arginine homozygotes (Pro-). All these phenomena are particularly evident in cells from centenarians. We conclude that the functional difference between the two p53 codon 72 alleles exerts a broadimpact on the capability of cell from aged people to respond to stressors such as cytotoxic drugs.

What studies on human longevity tell us about the risk for cancer in the oldest old: data and hypotheses on the genetics and immunology of centenarians.

Centenarians are people who escaped from major common diseases, including cancer, and reached the extreme limits of human life-span. The analysis of demographic data indicates that cancer incidence and mortality show a levelling off around the age of 85-90 years, and suggests that oldest old people and centenarians are protected from cancer onset and progression. In this paper, we review data of recent literature on the distribution in centenarians of germ-line polymorphisms, which are supposed to affect the individual susceptibility to cancer (p53, HRAS1, BRCA1, glutathione transferases, cytochrome oxidases, steroid-5 alpha-reductase enzyme type II). Moreover, we add new data on two p53 polymorphisms in a total of 1086 people of different age, including 307 centenarians. In addition, we put forth the hypothesis that the remodelling of the immune system occurring with age is capable of creating a hostile environment for the growth of cancer cells in these exceptional individuals. We conclude that future studies on centenarians regarding the germ-line variability of genes involved in the control of the immune response, including apoptosis (ApoJ), are likely to be of fundamental importance in understanding the basic mechanisms for cancer, aging and their complex relationship.