Long-term Multimodal Recording Reveals Epigenetic Adaptation Routes in Dormant Breast Cancer Cells.

Patients with estrogen receptor-positive breast cancer receive adjuvant endocrine therapies (ET) that delay relapse by targeting clinically undetectable micrometastatic deposits. Yet, up to 50% of patients relapse even decades after surgery through unknown mechanisms likely involving dormancy. To investigate genetic and transcriptional changes underlying tumor awakening, we analyzed late relapse patients and longitudinally profiled a rare cohort treated with long-term neoadjuvant ETs until progression. Next, we developed an in vitro evolutionary study to record the adaptive strategies of individual lineages in unperturbed parallel experiments. Our data demonstrate that ETs induce nongenetic cell state transitions into dormancy in a stochastic subset of cells via epigenetic reprogramming. Single lineages with divergent phenotypes awaken unpredictably in the absence of recurrent genetic alterations. Targeting the dormant epigenome shows promising activity against adapting cancer cells. Overall, this study uncovers the contribution of epigenetic adaptation to the evolution of resistance to ETs. SIGNIFICANCE: This study advances the understanding of therapy-induced dormancy with potential clinical implications for breast cancer. Estrogen receptor-positive breast cancer cells adapt to endocrine treatment by entering a dormant state characterized by strong heterochromatinization with no recurrent genetic changes. Targeting the epigenetic rewiring impairs the adaptation of cancer cells to ETs. See related commentary by Llinas-Bertran et al., p. 704. This article is featured in Selected Articles from This Issue, p. 695.

A Gradual Transition Toward Anaplasia in Wilms Tumor Through Tolerance to Genetic Damage.

Patients with Wilms tumor (WT) in general have excellent survival, but the prognosis of patients belonging to the subgroup of WT with diffuse anaplasia (DA) is poor due to frequent resistance to chemotherapy. We hypothesized that DA WT cells might undergo changes, such as acquiring a persistent tolerance to DNA damage and copy number aberrations (CNAs), which could eventually lead to their resistance to chemotherapy treatment. Tissue sections from chemotherapy-treated DA WTs (n = 12) were compared with chemotherapy-treated nonanaplastic WTs (n = 15) in a tissue microarray system, enabling analysis of 769 tumor regions. All regions were scored for anaplastic features and immunohistochemistry was used to quantify p53 expression, proliferation index (Ki67), and DNA double-strand breaks (γH2AX). CNAs were assessed by array-based genotyping and TP53 mutations using targeted sequencing. Proliferation index and the frequency of DNA double-strand breaks (γH2AX dot expression) increased with higher anaplasia scores. Almost all (95.6%) areas with full-scale anaplasia had TP53 mutations or loss of heterozygosity, along with an increased amount of CNAs. Interestingly, areas with wild-type TP53 with loss of heterozygosity and only one feature of anaplasia (anaplasia score 1) also had significantly higher proliferation indices, more DNA double-strand breaks, and more CNAs than regions without any anaplastic features (score 0); such areas may be preanaplastic cell populations under selective pressure for TP53 mutations. In conclusion, we suggest that chemoresistance of DA WTs may be partly explained by a high proliferative capability of anaplastic cells, which also have a high burden of double-stranded DNA breaks and CNAs, and that there is a gradual emergence of anaplasia in WT.

Periprosthetic effusions surrounding breast expander: a flow cytometric, immunohistochemical and molecular characterization.

INTRODUCTION: The synthesis of the periprosthetic capsule during implant-based breast reconstruction is the result of a coordinate cascade of inflammatory events ending in a fibrous tissue deposition around the expander or implant. Although the development of small volumes of fluid is one of the complications of prosthetic-based breast reconstruction, the characterization of the periprosthetic effusions coupled with the micro-textured devices, that have been recently introduced after the recall of macro-textured ones, is still lacking. The investigation of these periprosthetic effusions and paired capsules in terms of immunological content were the primary and secondary aims of the present study, respectively. METHODS: For this, 68 women, 41 of whom had periprosthetic effusions at the time of expander replacement with implant, were recruited. For each case, capsule and healthy dermal tissues were taken and for women with periprosthetic effusion, peripheral blood was also collected. Periprosthetic effusions and peripheral blood were characterized by cytometry while capsules and dermal tissues by immunohistochemistry and Nanostring analysis. RESULTS: The results showed an increase of Th1, Th2 lymphocytes and a HLA-DR+bright CD16+ cells (likely representing monocytes-derived macrophages) in periprosthetic effusions in respect to peripheral blood. These pro-inflammatory cells were counterbalanced by the gain of suppressive CD4 Treg cells. In the corresponding capsules, immunohistochemistry revealed the absence of Th1 cells and the presence of tissutal FOXP3 Treg. No significant difference in expression of inflammatory-related genes between capsules and dermal tissues was present. CONCLUSIONS: These results suggest the presence of a Treg-controlled inflammation in both periprosthetic effusions and capsules.

Psychobiological personality traits of children and adolescents with disorders of arousal.

INTRODUCTION: Disorders of arousal (DOA) are parasomnias that emerge from incomplete arousal out of Non-Rem Sleep (NREM) and lead to a broad variety of emotional and motor behaviours. Increasing evidence supports the hypothesis that specific psychopathological traits contribute to the multifactorial origin of these phenomena. The aim of the current multicenter study was to compare the personality profile of children and adolescents with and without DOA using the Junior Temperament and Character Inventory (JTCI). METHODS: We enrolled 36 patients with a diagnosis of DOA (mean age of 11 ± 3 years, 64% males), and 36 healthy age and gender matched control subjects (mean age of 11.2 ± 3.6, years, 67% males). Their parents completed the Paris Arousal Disorder Severity Scale (PADSS), the Sleep Disturbance Scale for Children (SDSC) and the JTCI. RESULTS: Patients with DOA reached significantly higher levels compared to their control group in total PADSS (p < 0.0001) and in total SDSC (p < 0.0001). They also displayed higher scores in novelty seeking (p = 0.005), harm avoidance (p = 0.01), self-transcendence (p = 0.006) JTCI subscales, and lower scores on the self-directedness subscale (p = 0.004). CONCLUSION: Our pediatric sample with DOA exhibited specific psychobiological personality traits compared to age and gender matched subjects without DOA. These results shed light on new possible etiopathogenetic mechanisms, as TCI traits have been linked to specific genetic variants and brain circuits, like the reward system. Prospective studies are required to assess the effect of targeted psychological/psychiatric treatment on DOA symptomatology.

Gene expression-based dissection of inter-histotypes, intra-histotype and intra-tumor heterogeneity in pediatric tumors.

Intra-tumor heterogeneity (ITH) fosters tumor evolution, resistance to therapy, and relapse. Recently, many evidence have been accumulated on the occurrence of genetic ITH in pediatric cancers. With this study we aimed to address the downstream effects that genetic and epigenetic ITH, and tumor-microenvironment interactions may produce within a tumor mass. To this aim, we investigated by high-throughput gene expression multiple samples of 5 hepatoblastomas, 5 neuroblastomas, 5 rhabdomyosarcomas, and 5 Wilms tumors. Principal component analysis, single sample hallmark gene sets analysis, and weighted gene co-expression network analysis were performed on gene expression data. We observed that the different tumors clustered by histotype, and then by case, and in addition, a variable degree of ITH was visible in all the investigated cases. The ITH highlighted in this study can represent a challenge in tumor treatment since we demonstrated that different druggable hallmarks and targets may be heterogeneously present within the same tumor mass, and this can potentially lead to therapeutic failure. Despite this heterogeneity, we could highlight some commonalities among the different histotypes investigated, supporting the feasibility to move in the clinic from a histotype-driven to a target-driven, sometimes agnostic, approach at least in some cases.

Renal cell carcinoma in children and adolescents: a retrospective study of a French-Italian series of 93 cases.

AIMS: Renal cell carcinomas (RCCs) represent 2-5% of kidney malignancies in children and adolescents. Appropriate diagnostic and classification are crucial for the correct management of the patients and in order to avoid inappropriate pre-operative chemotherapy, which is usually recommended if a Wilms' tumour is suspected. METHODS AND RESULTS: A French-Italian series of 93 renal cell carcinomas collected from 1990 to 2019 in patients aged less than 18 years was reclassified according to the 2016 World Health Organization (WHO) classification and the latest literature. TFE3 and TFEB fluorescence in-situ hybridisation (FISH) analyses and a panel of immunohistochemical stains were applied. The median age at diagnosis was 11 years (range = 9 months-17 years). MiT family (MiTF) translocation RCCs accounted for 52% of the tumours, followed by papillary (20%) and unclassified RCCs (13%). Other subtypes, such as SDHB-deficient and fumarate hydratase-deficient RCCs, represented 1-3% of the cases. We also described a case of ALK-rearranged RCC with a metanephric adenoma-like morphology. CONCLUSION: A precise histological diagnosis is mandatory, as targeted therapy could be applied for some RCC subtypes, i.e. MiTF-translocation and ALK-translocation RCC. Moreover, some RCC subtypes may be associated with a predisposition syndrome that will impact patients' and family's management and genetic counselling. A precise RCC subtype is also mandatory for the clinical management of the patients and inclusion in new prospective clinical trials.

Molecular Determinants of Soft Tissue Sarcoma Immunity: Targets for Immune Intervention.

Soft tissue sarcomas (STSs) are a family of rare malignant tumors encompassing more than 80 histologies. Current therapies for metastatic STS, a condition that affects roughly half of patients, have limited efficacy, making innovative therapeutic strategies urgently needed. From a molecular point of view, STSs can be classified as translocation-related and those with a heavily rearranged genotype. Although only the latter display an increased mutational burden, molecular profiles suggestive of an "immune hot" tumor microenvironment are observed across STS histologies, and response to immunotherapy has been reported in both translocation-related and genetic complex STSs. These data reinforce the notion that immunity in STSs is multifaceted and influenced by both genetic and epigenetic determinants. Cumulative evidence indicates that a fine characterization of STSs at different levels is required to identify biomarkers predictive of immunotherapy response and to discover targetable pathways to switch on the immune sensitivity of "immune cold" tumors. In this review, we will summarize recent findings on the interplay between genetic landscape, molecular profiling and immunity in STSs. Immunological and molecular features will be discussed for their prognostic value in selected STS histologies. Finally, the local and systemic immunomodulatory effects of the targeted drugs imatinib and sunitinib will be discussed.

Gut Microbiota Condition the Therapeutic Efficacy of Trastuzumab in HER2-Positive Breast Cancer.

Emerging evidence indicates that gut microbiota affect the response to anticancer therapies by modulating the host immune system. In this study, we investigated the impact of gut microbiota on immune-mediated trastuzumab antitumor efficacy in preclinical models of HER2-positive breast cancer and in 24 patients with primary HER2-positive breast cancer undergoing trastuzumab-containing neoadjuvant treatment. In mice, the antitumor activity of trastuzumab was impaired by antibiotic administration or fecal microbiota transplantation from antibiotic-treated donors. Modulation of the intestinal microbiota was reflected in tumors by impaired recruitment of CD4+ T cells and granzyme B-positive cells after trastuzumab treatment. Antibiotics caused reductions in dendritic cell (DC) activation and the release of IL12p70 upon trastuzumab treatment, a mechanism that was necessary for trastuzumab effectiveness in our model. In patients, lower α-diversity and lower abundance of Lachnospiraceae, Turicibacteraceae, Bifidobacteriaceae, and Prevotellaceae characterized nonresponsive patients (NR) compared with those who achieved pathologic complete response (R), similar to antibiotic-treated mice. The transfer of fecal microbiota from R and NR into mice bearing HER2-positive breast cancer recapitulated the response to trastuzumab observed in patients. Fecal microbiota ß-diversity segregated patients according to response and positively correlated with immune signature related to interferon (IFN) and NO2-IL12 as well as activated CD4+ T cells and activated DCs in tumors. Overall, our data reveal the direct involvement of the gut microbiota in trastuzumab efficacy, suggesting that manipulation of the gut microbiota is an optimal future strategy to achieve a therapeutic effect or to exploit its potential as a biomarker for treatment response. SIGNIFICANCE: Evidence of gut microbiota involvement in trastuzumab efficacy represents the foundation for new therapeutic strategies aimed at manipulating commensal bacteria to improve response in trastuzumab-resistant patients.See related commentary by Sharma, p. 1937 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/8/2195/F1.large.jpg.

The Leydig cell tumour Scaled Score (LeSS): a method to distinguish benign from malignant cases, with additional correlation with MDM2 and CDK4 amplification.

AIMS: To investigate the morphological and molecular characteristics of Leydig cell tumours (LCTs) of the testis for the identification of cases that may metastasise. METHODS AND RESULTS: Six parameters for a predictive model of the metastatic risk were evaluated in 37 benign and 14 malignant LCTs of the testis [LCT Scaled Score (LeSS)]. The tumour size (benign LCTs, mean 13.3 mm; malignant LCTs, mean 44 mm) (P < 0.001) and five other parameters (infiltrative margins, necrosis, vascular invasion, mitotic count, and nuclear atypia) showed significant differences (Wilcoxon's test, P < 0.001). Eight metastatic LCTs and one benign LCT had infiltrative margins. Foci of coagulative necrosis occurred in 10 metastatic LCTs, whereas vascular invasion was identified in nine of 14 metastatic LCTs and none of 37 benign LCTs. Benign LCTs showed <2 mitoses/10 high-power fields (HPFs), whereas a high mitotic count (range, 3-50 mitoses/10 HPFs) was a feature of malignant LCTs. These parameters were selected by use of an inferential analysis based on univariate logistic regression models to develop a score. A LeSS of <4 correctly identified all histologically and clinically benign LCTs. A LeSS of ≥4 correctly identified all malignant LCTs. MDM2 and CDK4 immunostains were applied in all 51 cases: benign LCTs were negative; three of 11 malignant LCTs (27%) showed strong and diffuse immunopositivity and high levels of MDM2 and CDK4 amplification as determined with fluorescence in-situ hybridisation analysis and next-generation sequencing. CONCLUSION: We provide a new tool, the LeSS, for the prediction of malignant behaviour in LCTs.

Myoid gonadal tumor. Case series, systematic review, and Bayesian analysis.

Myoid gonadal stromal tumor represents a rare testicular neoplasm displaying smooth muscular and gonadal stromal differentiation. This entity has very few cases reported in the literature that describe heterogeneous clinical and pathological characteristics. Bayesian statistics provides a useful framework to combine information from diverse sources. We here presented a case series-the largest so far reported-of myoid gonadal stromal tumor (4 cases) with extensive morphologic, immunohistochemical, and molecular characterization, performed a systematic review of the literature (that identified 9 papers), and used a Bayesian data analysis to understand the characteristics of this disease. Our study collectively described 16 cases. This neoplasm is mainly found in adults (mean age about 40 years) and often has a size of about 3 cm. By morphology, the tumor can infiltrate testicular tubules and is composed of spindle cells; few mitoses can be seen (usually 2/10 HPF). Neoplastic cells are diffusely positive with α-smooth muscle actin with a tram-track staining pattern. S100 protein, FOXL2, and SF1 are also characteristically positive. Moreover, this neoplasm can display epithelial differentiation, in about half of the cases. In conclusion, we foresee the use of this statistical approach in pathology: our analysis allowed a more precise description of this rare entity.

Analysis of the mutational status of SIX1/2 and microRNA processing genes in paired primary and relapsed Wilms tumors and association with relapse.

Whereas 90% of patients with Wilms tumor (WT) reach cure, approximately half of patients developing a recurrent tumor die of the disease. Therefore, to disclose events leading to recurrence represents a clinical need. To study paired primary/recurrent tumor samples, being aware of the intra-tumoral heterogeneity, might help finding these answers. We previously suggested that mutations in SIX1 and DROSHA underlie WT recurrence. With the aim to better investigate this scenario, we collected 19 paired primary/recurrent tumors and 10 primary tumors from relapsing patients and searched for mutations in the SIX1/2 genes and microRNA processing genes (miRNAPGs). We found SIX1 mutation in one case, miRNAPGs mutations in seven cases, and the co-occurrence of SIX1 and miRNAPG mutations in one case. We could observe that, whereas in primary tumors the mutations could be heterogeneously present, in all cases they were positively selected and homogeneously present in the recurrent disease, as also indicated by a "moderate" and "almost perfect" agreement (according to the Landis and Koch classification criteria) between paired samples. Analysis of SIX1/2 genes and miRNAPGs in 50 non-relapsing WTs disclosed SIX2 mutation in one case and miRNAPGs mutations in seven. A borderline statistically significant association was observed between miRNAPGs mutations and the occurrence of relapse (p value: 0.05). These data suggest that SIX1 and miRNAPGs mutations may provide an advantage during tumor progression to recurrence and can represent oncogenic drivers in WT development.

A cell-of-origin epigenetic tracer reveals clinically distinct subtypes of high-grade serous ovarian cancer.

BACKGROUND: High-grade serous ovarian cancer (HGSOC) is a major unmet need in oncology. The remaining uncertainty on its originating tissue has hampered the discovery of molecular oncogenic pathways and the development of effective therapies. METHODS: We used an approach based on the retention in tumors of a DNA methylation trace (OriPrint) that distinguishes the two putative tissues of origin of HGSOC, the fimbrial (FI) and ovarian surface epithelia (OSE), to stratify HGSOC by several clustering methods, both linear and non-linear. The identified tumor subtypes (FI-like and OSE-like HGSOC) were investigated at the RNAseq level to stratify an in-house cohort of macrodissected HGSOC FFPE samples to derive overall and disease-free survival and identify specific transcriptional alterations of the two tumor subtypes, both by classical differential expression and weighted correlation network analysis. We translated our strategy to published datasets and verified the co-occurrence of previously described molecular classification of HGSOC. We performed cytokine analysis coupled to immune phenotyping to verify alterations in the immune compartment associated with HGSOC. We identified genes that are both differentially expressed and methylated in the two tumor subtypes, concentrating on PAX8 as a bona fide marker of FI-like HGSOC. RESULTS: We show that: - OriPrint is a robust DNA methylation tracer that exposes the tissue of origin of HGSOC. - The tissue of origin of HGSOC is the main determinant of DNA methylation variance in HGSOC. - The tissue of origin is a prognostic factor for HGSOC patients. - FI-like and OSE-like HGSOC are endowed with specific transcriptional alterations that impact patients' prognosis. - OSE-like tumors present a more invasive and immunomodulatory phenotype, compatible with its worse prognostic impact. - Among genes that are differentially expressed and regulated in FI-like and OSE-like HGSOC, PAX8 is a bona fide marker of FI-like tumors. CONCLUSIONS: Through an integrated approach, our work demonstrates that both FI and OSE are possible origins for human HGSOC, whose derived subtypes are both molecularly and clinically distinct. These results will help define a new roadmap towards rational, subtype-specific therapeutic inroads and improved patients' care.

Frequent mutation and nuclear localization of ß-catenin in sertoli cell tumors of the testis.

The Sertoli cell tumor (SCT) of the testis is a sex cord stromal tumor, usually sporadic, rarely associated with genetic syndromes. Much remains unclear about the molecular genetic changes involved in SCT and its histogenesis. Recently, nuclear ß-catenin immunostaining has been reported in a case of bilateral SCT, but the molecular basis of the aberrant nuclear ß-catenin expression remains uncertain. In the present study, ß-catenin immunohistochemical assay and mutational analysis of exon 3 of the CTNNB1 gene by direct sequencing were performed in 14 SCTs, 2 of which had an unfavorable clinical course. Immunohistochemical study showed that ß-catenin was located in the cytoplasm of tumor cells in 4 cases (28.6%) and in both the nuclei and the cytoplasm in the remaining 10 cases (71.4%). ß-Catenin mutations were detected in 10 of the 14 patients (71.4%) under evaluation. Ten of 10 mutation-carrying cases showed strong nuclear and diffuse cytoplasmic ß-catenin immunoreactivity. Seven of the 8 CTNNB1-mutated tumors tested for cyclin D1 displayed diffuse immunoreactivity in the nuclei of tumor cells. We conclude that CTNNB1 exon 3 mutations are likely to be involved in the pathogenesis of male SCT with nuclear accumulation of ß-catenin and affect the expression of cyclin D1.

Genetic control of renal tumorigenesis by the mouse Rtm1 locus.

BACKGROUND: The genetic basis of susceptibility to renal tumorigenesis has not yet been established in mouse strains. Mouse lines derived by bidirectional phenotypic selection on the basis of their maximal (AIRmax) or minimal (AIRmin) acute inflammatory responsiveness differ widely in susceptibility to spontaneous and urethane-induced renal tumorigenesis. To map the functional loci modulating renal tumor susceptibility in these mice, we carried out a genome-wide genetic linkage study, using SNP arrays, in an (AIRmax x AIRmin)F2 intercross population treated with a single urethane dose at 1 week of age and phenotyped for renal tumors at 35 weeks of age. RESULTS: AIRmax mice did not develop renal tumors spontaneously nor in response to urethane, whereas in AIRmin mice renal tumors formed spontaneously (in 52% of animals) and after urethane induction (89%). The tumors had a papillary morphology and were positive for alpha-methylacyl-CoA racemase and negative for CD10. By analysis of 879 informative SNPs in 662 mice, we mapped a single quantitative trait locus modulating the incidence of renal tumors in the (AIRmax x AIRmin)F2 intercross population. This locus, which we named Renal tumor modifier QTL 1 (Rtm1), mapped to chromosome 17 at 23.4 Mb (LOD score = 15.8), with SNPs rs3696835 and rs3719497 flanking the LOD score peak. The A allele of rs3719497 from AIRmin mice was associated with a 2.5-fold increased odds ratio for renal tumor development. The LOD score peak included the Tuberous sclerosis 2 (Tsc2) gene which has already been implicated in kidney disease: loss of function by germline retroviral insertion is associated with spontaneous renal tumorigenesis in the Eker rat, and heterozygous-null Tsc2(+/-) mice develop renal cystadenomas. CONCLUSIONS: We mapped Rtm1 as a single major locus modulating renal tumorigenesis in a murine intercross population. Thus, the AIR mouse lines can be considered a new genetic model for studying the role of germline and somatic molecular alterations in kidney neoplastic disease.

Investigation of the mechanisms underpinning IL-6 cytokine release in bystander responses: the roles of radiation dose, radiation quality and specific ROS/RNS scavengers.

PURPOSE: To investigate the mechanisms regulating the pathways of the bystander transmission in vitro, focusing on the radiation-perturbed signalling (via Interleukine 6, IL-6) of the irradiated cells after exposure to low doses of different radiation types. MATERIALS AND METHODS: An integrated 'systems radiation biology' approach was adopted. Experimentally the level of the secreted cytokine from human fibroblasts was detected with ELISA (Enzyme-Linked ImmunoSorbent Assay) method and subsequently the data were analyzed and coupled with a phenomenological model based on differential equations to evaluate the single-cell release mechanisms. RESULTS: The data confirmed the important effect of radiation on the IL-6 pathway, clearly showing a crucial role of the ROS (Reactive Oxygen Species) in transducing the effect of initial radiation exposure and the subsequent long-term release of IL-6. Furthermore, a systematic investigation of radiation dose/radiation quality dependence seems to indicate an increasing efficiency of high LET (Linear Energy Transfer) irradiation in the release of the cytokine. Basic hypotheses were tested, on the correlation between direct radiobiological damage and signal release and on the radiation target for this endpoint (secretion of IL-6). CONCLUSIONS: The results demonstrate the role of reactive oxygen and nitrogen species in the signaling pathways of IL-6. Furthermore the systems radiation biology approach here adopted, allowed us to test and verify hypotheses on the behavior of the single cell in the release of cytokine, after the exposure to different doses and different qualities of ionizing radiation.

Effects of ionizing radiation on cell-to-cell communication.

Cell-to-cell signaling has become a significant issue in radiation biology due to experimental evidence, accumulated primarily since the early 1990s, of radiation-induced bystander effects. Several candidate mediators involved in cell-to-cell communication have been investigated and proposed as being responsible for this phenomenon, but the current investigation techniques (both theoretical and experimental) of the mechanisms involved, due to the particular set-up of each experiment, result in experimental data that often are not directly comparable. In this study, a comprehensive approach was adopted to describe cell-to-cell communication (focusing on cytokine signaling) and its modulation by external agents such as ionizing radiation. The aim was also to provide integrated theoretical instruments and experimental data to help in understanding the peculiarities of in vitro experiments. Theoretical/modeling activities were integrated with experimental measurements by (1) redesigning a cybernetic model (proposed in its original form in the 1950s) to frame cell-to-cell communication processes, (2) implementing and developing a mathematical model, and (3) designing and carrying out experiments to quantify key parameters involved in intercellular signaling (focusing as a pilot study on the release and decay of IL-6 molecules and their modulation by radiation). This formalization provides an interpretative framework for understanding the intercellular signaling and in particular for focusing on the study of cell-to-cell communication in a "step-by-step" approach. Under this model, the complex phenomenon of signal transmission was reduced where possible into independent processes to investigate them separately, providing an evaluation of the role of cell communication to guarantee and maintain the robustness of the in vitro experimental systems against the effects of perturbations.

The effects of alginate encapsulation on NIT-1 insulinoma cells: viability, growth and insulin secretion.

Transplantation of microencapsulated insulin-secreting cells is proposed as a promising therapy for the treatment of type I diabetes mellitus. In recent years, important advances have been made in the field of immunoisolation and many studies have shown that alginate provides some major advantages for encapsulation over other systems. Since it is known that the extracellular matrix influences the behaviour of encapsulated cells, the aim of the present work has been to study the consequences of encapsulation on some cell functions. For this purpose, cell growth and dynamics of insulin release of NIT-1 cells entrapped in alginate capsules compared with those exhibited by free NIT-1 cells were investigated by means of growth curves, assays, Trypan blue staining and ELISA test. All investigations performed allowed us to conclude that alginate-entrapped NIT-1 cells maintain their growth features and secretory functions although with some important differences. In particular, alginate encapsulation affects the cellular growth profile and causes the lost of time dependence of insulin secretion profile.

Experimental and theoretical analysis of cytokine release for the study of radiation-induced bystander effect.

PURPOSE: To clarify the experimental conditions that might influence the release of cytokines in the culture medium and give some basic input for building a model for cytokine (e.g., Interleukin-6, IL-6) regulation in the case of 'sham irradiation' and after ionising radiation exposure. MATERIALS AND METHODS: The influence of cell type, cell density, medium volume, medium storage temperature and other methodological aspects on IL-6 and Interleukin-8 (IL-8) release were investigated. In addition, the effects over the time of different doses of gamma irradiation on the clonogenic survival of bystander cells and on the secretion of these cytokines were studied. RESULTS: We observed significant decreases of clonogenic survival in AG01522 and T98G cells after the transfer of medium collected 5 and 20 h after low doses of gamma irradiation. Concerning the Interleukins' measurements, our experiments showed that the aggregate removal modalities tested, and up to 10 freeze-thaw cycles, do not have significant influence on the measurements of IL-6 concentration in the medium. We also observed that the IL-6 accumulated in the medium of human fibroblasts is not degraded when maintained at 37 degrees C. Sets of experiments demonstrated that cell density or medium volume do not influence the release of IL-6. On the contrary, our results showed that IL-8 released by glioblastoma cells strongly depends on the amount of medium. Finally, the exposure of fibroblasts to gamma irradiation has influence on the release kinetics of both IL-6 and IL-8 with peculiar features. CONCLUSIONS: This study solved some of the methodological doubts concerning the study of bystander effects by means of the medium transfer technique; moreover it also highlighted some experimental aspects that need to be considered when approaching this sort of experiments.