Integrated Multi-omics Analysis of Early Lung Adenocarcinoma Links Tumor Biological Features with Predicted Indolence or Aggressiveness

Lung adenocarcinoma (LUAD) is a heterogeneous group of tumors associated with different survival rates, even when detected at an early stage. Here, we aim to investigate the biological determinants of early LUAD indolence or aggressiveness using radiomics as a surrogate of behavior. We present a set of 92 patients with LUAD with data collected across different methodologies. Patients were risk-stratified using the CT-based Score Indicative of Lung cancer Aggression (SILA) tool (0 = least aggressive, 1 = most aggressive). We grouped the patients as indolent (x ≤ 0.4, n = 14), intermediate (0.4 > x ≤ 0.6, n = 27), and aggressive (0.6 > x ≤ 1, n = 52). Using Cytometry by time of flight (CyTOF), we identified subpopulations with high HLA-DR expression that were associated with indolent behavior. In the RNA sequencing (RNA-seq) dataset, pathways related to immune response were associated with indolent behavior, while pathways associated with cell cycle and proliferation were associated with aggressive behavior. We extracted quantitative radiomics features from the CT scans of the patients. Integrating these datasets, we identified four feature signatures and four patient clusters that were associated with survival. Using single-cell RNA-seq, we found that indolent tumors had significantly more T cells and less B cells than aggressive tumors, and that the latter had a higher abundance of regulatory T cells and Th cells. In conclusion, we were able to uncover a correspondence between radiomics and tumor biology, which could improve the discrimination between indolent and aggressive LUAD tumors, enhance our knowledge in the biology of these tumors, and offer novel and personalized avenues for intervention.

Significance

This study provides a comprehensive profiling of LUAD indolence and aggressiveness at the biological bulk and single-cell levels, as well as at the clinical and radiomics levels. This hypothesis generating study uncovers several potential future research avenues. It also highlights the importance and power of data integration to improve our systemic understanding of LUAD and to help reduce the gap between basic science research and clinical practice.

HLA-DR cancer cells expression correlates with T cell infiltration and is enriched in lung adenocarcinoma with indolent behavior

Lung adenocarcinoma (ADC) is a heterogeneous group of tumors associated with different survival rates, even when detected at an early stage. Here, we aim to investigate whether CyTOF identifies cellular and molecular predictors of tumor behavior. We developed and validated a CyTOF panel of 34 antibodies in four ADC cell lines and PBMC. We tested our panel in a set of 10 ADCs, classified into long- (LPS) (n = 4) and short-predicted survival (SPS) (n = 6) based on radiomics features. We identified cellular subpopulations of epithelial cancer cells (ECC) and their microenvironment and validated our results by multiplex immunofluorescence (mIF) applied to a tissue microarray (TMA) of LPS and SPS ADCs. The antibody panel captured the phenotypical differences in ADC cell lines and PBMC. LPS ADCs had a higher proportion of immune cells. ECC clusters (ECCc) were identified and uncovered two ADC groups. ECCc with high HLA-DR expression were correlated with CD4+ and CD8+ T cells, with LPS samples being enriched for those clusters. We confirmed a positive correlation between HLA-DR expression on ECC and T cell number by mIF staining on TMA slides. Spatial analysis demonstrated shorter distances from T cells to the nearest ECC in LPS. Our results demonstrate a distinctive cellular profile of ECC and their microenvironment in ADC. We showed that HLA-DR expression in ECC is correlated with T cell infiltration, and that a set of ADCs with high abundance of HLA-DR+ ECCc and T cells is enriched in LPS samples. This suggests new insights into the role of antigen presenting tumor cells in tumorigenesis.

Abstract PO-045: Single cell proteomic analysis of lung adenocarcinoma identifies high HLA-DR expression to be associated with indolent tumor behavior

Lung adenocarcinoma (ADC) is a heterogeneous group of tumors associated with dramatically different survival rates, even when detected at an early stage. We hypothesized that a single cell proteomic approach would allow the dissection of cellular determinants of early lung ADC behavior. We developed a mass cytometry panel of 34 antibodies and validated their performance in four ADC cell lines (A459, H23, PC9 and H3211) and immune cells. We tested our panel in a set of 10 early stage lung ADCs, classified into long- (LPS) (n=4) and short-predicted survival (SPS) (n=6) based on radiomics features. Tumors were disaggregated and cryopreserved until mass cytometry analysis. We identified cellular subpopulations by clustering and analyzed differences in their distribution both within the tumor microenvironment and the epithelial compartment. To validate our results a tissue micro array was generated from lung tissue blocks from patients with LPS and SPS lung adenocarcinoma. Fluorescent staining was performed for PanCK, CD45, CD3, HLA-DR, DAPI. Cell nuclei were segmented using deep learning algorithm and were further processed in KNIME analytical platform where cell segmentation, feature extraction and cell classification were performed. The antibody panel captured the phenotypical differences in ADCs cell lines and PBMCs. When tumors were analyzed long-predicted survival tumors had a higher proportion of immune cells, whereas some short-predicted survival tumors had a higher proportion of fibroblasts/mesenchymal cells. Additionally, tumors show high degree of heterogeneity with distinct protein expression profiles among epithelial subpopulations, and some subsets with high HLA-DR expression were positively correlated with CD4+ and CD8+ T cells with LPS samples being enriched for such subsets. These results were further validated by Fluorescent staining on TMA slides. We found a positive correlation between HLA-DR expression on tumor cells and T cell number (r = 0.25, p = 2.2e-05). For this, in neighborhoods of 100 um diameter for each tumor cell, HLA-DR median signal intensity on neighboring tumor cells and number of T cells were calculated in Python and used as inputs for correlative analysis. Spatial analysis was performed in KNIME by calculation of distances from each T cell to nearest 1st and 2nd tumor cell, for which LPS tumors showed smaller distances for both 1st and 2nd tumor cell compared to SPS tumors (p = 0.039, p = 0.21). Our results demonstrate a distinct cellular profile of epithelial and stromal cells among indolent vs aggressive ADCs with higher HLA-DR expression in indolent tumors, which is associated with greater T cell infiltration. Our results illustrate the heterogeneity of T cell responses and HLA DR expression in lung adenocarcinoma and should further our understanding of mechanisms related to tumorigenesis. This work deserves further validation at the cellular and molecular level to gain further insights into tumor behavior. The work was supported by CA196405 to PPM.

Citation Format: Maria-Fernanda Senosain, Tatiana Novitskaya, Georgii Vasiukov, Yong Zou, Aneri Balar, Deon B. Doxie, Jonathan M. Lehman, Rosana Eisenberg, Fabien Maldonado, Andries Zijlstra, Sergey V. Novitskiy, Jonathan M. Irish, Pierre P. Massion. Single cell proteomic analysis of lung adenocarcinoma identifies high HLA-DR expression to be associated with indolent tumor behavior [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-045.

Abstract 2692: Novel chemotherapy stable subpopulations are conserved across multiple small cell lung carcinoma patient derived xenograft models

Introduction: Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma of the lung responsible for up to 25% of lung cancer deaths and the 6th leading cause of cancer death. SCLC initially responds well to chemotherapy, but inevitably recurs even after initial complete responses. The etiology of this relapse is likely secondary to tumor heterogeneity and/or chemotherapy resistance subpopulations reconstituting tumor. Characterization of these resistant subpopulations could yield novel therapeutic targets for SCLC treatment. Mass cytometry uses metal labeled antibodies to profile expression and phosphorylation of multiple proteins in a single cell and offers the opportunity to identify new subpopulations as targets for novel therapies in SCLC.

Methods: Nude mice with SCLC patient derived xenografts (PDXs) were treated with a single cycle of carboplatin/etoposide or saline injection. PDX samples were stained with a 26-35 marker panel and an intercalator dye to identify nucleated cells. This panel measured phospho-signaling, neuroendocrine, immune, and mesenchymal cell markers, and functional markers including ki67 and cleaved caspase 3. Mouse cells, including leukocytes, were excluded using mouse MHC1 gating and Histone H3 was used to identify nucleated cells Single cell protein expression and phosphorylation was analyzed using viSNE, manual gating, as well as unsupervised clustering approaches with SPADE to identified multiple subpopulations with neuroendocrine and non-neuroendocrine features. Subpopulations were compared across multiple patient derived xenograft (PDX) models with and without chemotherapy treatment.

Results: Patient derived Xenograft (PDX) tumors across 3 distinct models including with and without a single cycle of chemotherapy treatment released viable tumor and stromal cells suitable for cryopreservation and mass cytometry. Chemotherapy treated tumors had dramatic changes in subpopulation distribution compared to matched mock treated tumor. This included enrichment in EPCAM+, CD24+, CD44- progenitor like subpopulations. Similar patterns of population shift were observed in multiple models. Of note, chemotherapy stable subpopulations were conserved across 5 different PDX models including SOX2+ and Oct ¾+ tumor populations. These subpopulations sorted similarly in multidimensional space in multiple PDX models suggesting conserved origins.

Conclusions: Mass cytometry was able to identify multiple NE and non-neuroendocrine cell populations from SCLC PDXs and characterize their signaling include rare subpopulations with stem like signaling factors of interest. Chemotherapy treated PDX had differential subpopulation distribution with enrichment of progenitor like cells with chemotherapy treatment similar to previous work in mouse genetic SCLC. However, rare conserved chemotherapy stable subpopulations enriched in stem-like signaling factors were identified across 5 PDX models including those with and without chemotherapy treatment. This work raises the possibility that chemotherapy stable subpopulations may contribute to progenitor populations which lead to relapse. Future work in this lab will focus on characterizing the stem like features of these subpopulations and their phenotypic dynamics and signaling.

Citation Format: Jonathan M. Lehman, Jeremy Staub, Yong Zou, Jonathan Irish, Pierre Massion. Novel chemotherapy stable subpopulations are conserved across multiple small cell lung carcinoma patient derived xenograft models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2692.

Somatostatin receptor 2 targeting in small cell lung carcinoma: perspectives

Small Cell lung carcinoma (SCLC) is the most lethal and aggressive subtype of lung cancer. Novel targeting approaches and agents are desperately needed. In this perspectives, we briefly explore recent data published in the International Journal of Cancer suggesting Somatostatin Receptor 2 (SSTR2) as a viable target for SCLC, summarize the current clinical trial space, and describe promising new research and clinical directions for Somatostatin Receptor 2 targeting in SCLC.

Author Correction: Molecular subtypes of small cell lung cancer: a synthesis of human and mouse model data

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Abstract 4701: Single cell mass cytometry analysis distinguishes indolent from aggressive lung adenocarcinomas

Lung adenocarcinoma (ADC) is a heterogeneous group of tumors associated with dramatically different survival rates, even when detected at an early stage. The overarching goal of our research is to identify the cellular and molecular predictors of indolent and aggressive behavior of early lung ADCs. In the work presented here, we hypothesized that mass cytometry, a single cell proteomic approach, would allow the discovery of cellular determinants of early lung ADC behavior. To test this hypothesis, we prepared a mass cytometry panel of 34 labeled antibodies and validated their performance in four lung ADC cell lines (A459, H23, PC9 and H3211), and in peripheral blood mononuclear cells (PBMCs). We then tested our panel in a set of 11 early stage lung ADCs. Based on radiomics features, four of these ADCs were predicted to have long (LS), one intermediate and 6 short survival (SS) establishing the rationale for the comparisons. Tumors were disaggregated into a single cell suspension within one hour after resection and cryopreserved before mass cytometry analysis. We used unsupervised clustering algorithm FlowSOM to identify cellular subpopulations and analyze differences in their distribution both within the tumor microenvironment (TME) and the epithelial compartment. We found that predicted LS tumors had a higher proportion of leukocytes (p-value = 0.027), moderately enriched in CD8+ T cells (p-value = 0.5671), whereas predicted SS tumors had a higher proportion of fibroblasts/mesenchymal cells (p-value = 0.138). Additionally, tumors show high degree of heterogeneity with distinct protein expression profiles among epithelial subpopulations. Epithelial subsets with high vimentin and low HLA-DR, and other subsets expressing p-ERK and p-S6 were mainly present in predicted SS tumors, whereas subsets with a high HLA-DR and low vimentin were mainly present in predicted LS tumors. Also, similarities on the subsets distribution in some samples suggest the presence of ADC molecular subtypes. It remains to elucidate if the observed heterogeneity of the epithelial compartment in combination with a specific composition of the TME could lead to a stronger association with predicted survival. Our preliminary results of mass cytometry in early lung ADCs confirm a distinct cellular profile of epithelial and stromal cells among indolent vs aggressive ADCs. This work deserves further validation at the cellular and molecular level to gain further insights into tumor behavior. [Supported by UO1CA196405 to PPM.]

Citation Format: Maria-Fernanda Senosain, Yong Zou, Deon B. Doxie, Aneri Balar, Rosana Eisenberg, Jonathan M. Lehman, Jonathan M. Irish, Pierre P. Massion. Single cell mass cytometry analysis distinguishes indolent from aggressive lung adenocarcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4701.

Molecular subtypes of small cell lung cancer: a synthesis of human and mouse model data

Small cell lung cancer (SCLC) is an exceptionally lethal malignancy for which more effective therapies are urgently needed. Several lines of evidence, from SCLC primary human tumours, patient-derived xenografts, cancer cell lines and genetically engineered mouse models, appear to be converging on a new model of SCLC subtypes defined by differential expression of four key transcription regulators: achaete-scute homologue 1 (ASCL1; also known as ASH1), neurogenic differentiation factor 1 (NeuroD1), yes-associated protein 1 (YAP1) and POU class 2 homeobox 3 (POU2F3). In this Perspectives article, we review and synthesize these recent lines of evidence and propose a working nomenclature for SCLC subtypes defined by relative expression of these four factors. Defining the unique therapeutic vulnerabilities of these subtypes of SCLC should help to focus and accelerate therapeutic research, leading to rationally targeted approaches that may ultimately improve clinical outcomes for patients with this disease.

Somatostatin receptor 2 signaling promotes growth and tumor survival in small-cell lung cancer

Somatostatin receptor 2 (SSTR2) is overexpressed in a majority of neuroendocrine neoplasms, including small-cell lung carcinomas (SCLCs). SSTR2 was previously considered an inhibitory receptor on cell growth, but its agonists had poor clinical responses in multiple clinical trials. The role of this receptor as a potential therapeutic target in lung cancer merits further investigation. We evaluated the expression of SSTR2 in a cohort of 96 primary tumors from patients with SCLC and found 48% expressed SSTR2. Correlation analysis in both CCLE and an SCLC RNAseq cohort confirmed high-level expression and identified an association between NEUROD1 and SSTR2. There was a significant association with SSTR2 expression profile and poor clinical outcome. We tested whether SSTR2 expression might contribute to tumor progression through activation of downstream signaling pathways, using in vitro and in vivo systems and downregulated SSTR2 expression in lung cancer cells by shRNA. SSTR2 downregulation led to increased apoptosis and dramatically decreased tumor growth in vitro and in vivo in multiple cell lines with decreased AMPKα phosphorylation and increased oxidative metabolism. These results demonstrate a role for SSTR2 signaling in SCLC and suggest that SSTR2 is a poor prognostic biomarker in SCLC and potential future therapeutic signaling target.

Abstract 2180: Investigating lung adenocarcinoma tumor heterogeneity with single-cell mass cytometry

The lack of accuracy in predicting behavior of early detected lung adenocarcinoma (ADC) presents a major challenge to patients and their providers. Indolent tumors may be overdiagnosed and overtreated. While imaging tools may contribute to better prediction of tumor behavior, unveiling tumor heterogeneity of ADCs at the single-cell level will elucidate mechanisms of tumor progression. Mass cytometry allows us to profile tumor heterogeneity and identify cell populations driven by the activation of specific signaling pathways. We report the development of an antibody panel for mass cytometry and preliminary experiments in cancer cell lines and in ADC. ADCs were collected at the time of surgery, dissociated into suspension and cryopreserved within 24 hours. A mass cytometry antibody panel was developed, including commercially available and in-house metal conjugated antibodies. Biaxial gating or unsupervised analysis approaches SPADE and viSNE were used to compare major populations of cells. Our comprehensive antibody panel includes markers for cellular lineage (14) (immune, epithelial, mesenchymal, fibroblasts), cancer cells (3), signaling pathways (15) and quality control markers (2). The in-house conjugated antibodies (9/34) were titrated in concentrations going from 0 to 1 ug/mL using cell lines with known expression of the marker of interest. A panel of previously validated antibodies was used to gate cell populations. Signal medians of positive and negative populations and standard deviations of negative population were used to determine the stain index and the signal/noise ratio. Based on titration curves, optimal concentrations of antibody were selected for use. In the tumor studied, four cell populations were identified: endothelial cells, fibroblasts, epithelial tumor cells and leukocytes. Basal kinase activity was detected in cancer cells and infiltrating leukocytes, both exhibiting p-STAT5 activation, and cancer cells showing high p-AKT activation. Using our Marker Enrichment Modeling algorithm, we identified 3 differentially enriched subpopulations of tumor cells, as well as different leukocyte populations. These preliminary data proved mass cytometry and the panel developed are suitable tools to characterize tumor heterogeneity in lung ADC. The work in progress studying indolent and aggressive ADCs promises to identify detailed phenotypes and respective signaling pathway activation that may ultimately allow us to better predict tumor behavior and integrate this knowledge in the clinical workflow.

Supported by CA196415.

Citation Format: Maria-Fernanda Senosain-Ortega, Yong Zou, Deon B. Doxie, Caroline E. Roe, Jonathan M. Lehman, Jonathan M. Irish, Pierre P. Massion. Investigating lung adenocarcinoma tumor heterogeneity with single-cell mass cytometry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2180.

Abstract 3935: Dissecting small cell lung carcinoma heterogeneity and chemotherapy resistance with mass cytometry

Introduction: Small cell lung cancer (SCLC) is a high grade neuroendocrine carcinoma of the lung responsible for up to 25% of lung cancer deaths. Treatment in SCLC has not changed significantly in the last 20 years. SCLC initially responds well to chemotherapy, but inevitably recurs. Characterization of tumor heterogeneity and changes in SCLC cell signaling and phenotypes after chemotherapy could yield new insights and therapeutic options. Mass cytometry uses metal labeled antibodies to profile expression and phosphorylation of more than 40 proteins in single cells and offers the opportunity to identify new subpopulations including potential cancer stem cell populations as well as targets for novel therapies in SCLC.

Methods: Nude mice with SCLC patient derived xenografts (PDXs) were treated with one cycle of carboplatin/etoposide or saline injection. Tumors were harvested at ~2000mm3, disaggregated, and cryopreserved. PDX samples were stained with a 22 marker panel and an intercalator dye to identify nucleated cells. This panel measured phospho-signaling, neuroendocrine, immune, and mesenchymal cell markers, and functional markers including ki67 and cleaved caspase 3. ViSNE analysis and biaxial gating were used to identify major subpopulations of interest.

Results: PDX tumors released viable tumor and stromal cells suitable for cryopreservation and mass cytometry. ACK buffer and enzymatic dissociation yielded the best quality cells by depleting red blood cells. Mouse cells, including leukocytes, were excluded using mouse MHC1 gating and iridium intercalator was used to identify nucleated cells. Single cell protein expression and phosphorylation was analyzed using viSNE and yielded at least 9 distinct subpopulations based on density islands with neuroendocrine (CD56+) and non-neuroendocrine (CD56-) populations. Chemotherapy treated cells had dramatic changes in subpopulation distribution compared to matched mock treated tumor. This included 2-3 fold expansion of SOX2+, CD117+, and pSTAT3+ populations with chemotherapy treatment. A small CD44+ tumor subpopulation identified in the chemotherapy treated cells was not present in the matched mock treated tumor suggesting a potential chemotherapy resistant/ stem- like subpopulation. Kinase activity showed stable p-AKT overall, but increased p-S6 in the chemotherapy treated cells.

Conclusions: Mass cytometry was able to identify multiple neuroendocrine and non-neuroendocrine cell populations from SCLC PDXs and characterize their signaling. Chemotherapy treated PDX had differential subpopulation distribution with enrichment of multiple stem-like signaling factors. This work demonstrates the utility of mass cytometry and viSNE as novel techniques to identify subpopulations associated with chemotherapy resistance for future targeting and demonstrates the feasibility of this technique for characterizing signaling heterogeneity in human SCLC tumors.

Citation Format: Jonathan M. Lehman, Nalin Leelatian, Bradford Harris, Megan Hoeksema, Zou Yong, Deon B. Doxie, Jonathan M. Irish, Pierre P. Massion. Dissecting small cell lung carcinoma heterogeneity and chemotherapy resistance with mass cytometry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3935. doi:10.1158/1538-7445.AM2017-3935

Abstract 2911: Single cell mass cytometry analysis of human lung adenocarcinoma

Introduction: Lung cancer is the leading cause of cancer-related mortality in the world. Lung adenocarcinoma is the most common subtype. Tumor heterogeneity among adenocarcinomas presents a challenge in the management of the disease. Understanding heterogeneity may have implications in understanding the biological processes driving progression. Single cell platforms like mass cytometry offer an opportunity to profile tumor heterogeneity and to identify populations of driven by the activation of signaling pathways.

Methods: Adenocarcinomas were collected at the time of surgery and dissociated into suspension and cryopreserved. Mass cytometry analysis of tumors and adenocarcinoma cell lines was performed with a 30 marker antibody panel and rhodium intercalator dye to identify dead cells. The antibody panel included markers to characterize identity, cell cycle status, and signaling events. Biaxial gating or unsupervised analysis approaches SPADE and viSNE were used to compare major populations of cells.

Results: Validation of mass cytometry panels was performed with adenocarcinoma cell lines and human tumors. Adenocarcinoma cell lines PC9 (lung), A549 (lung), H520 (squamous) and SW620 (colon) exhibited phenotypically distinct cells between samples by expression of cytokeratin, CK7, and EGFR. Furthermore, PD-L1 expression was expressed on subsets within cell lines. Disaggregation of tumors was optimized with dissociation that included collagenase and DNase to release viable cells within 1 hour. Detection of viable cells was optimized with rhodium intercalator viability dye and histone H3 to identify nucleated cells. Using the 30 marker panel and viSNE analysis four populations were identified within tumors as infiltrating leukocytes, endothelial cells, fibroblast, and epithelial tumor cells. Epithelial cells were found to exhibit cellular heterogeneity between patients based on the expression of cytokeratin, CK7, TTF1, EGFR, vimentin, CD44, and MET. Preliminary signaling data identified basal kinase activity active in infiltrating leukocytes and cancer cells. Cancer cells and infiltrating immune cells had basal p-STAT5 activation, and cancer cells had high basal p-AKT implicated in dysregulated cell growth.

Conclusions: Populations of infiltrating stromal cells and epithelial (cancer) cells were identified in lung adenocarcinoma. The single cell phenotyping from tumors was consistent with the profile found in two lung adenocarcinoma cell lines. Preliminary differences in basal signaling pathways responsible for growth were observed within adenocarcinoma cell populations. This work demonstrates the feasibility of mass cytometry to identify and characterize tumor heterogeneity. Work is underway to define phenotypes within the epithelial and leukocyte populations that could predict tumor behavior and immune response within the microenvironment. This work is supported by NCI CA196405 to PPM.

Citation Format: Deon B. Doxie, Jonathan M. Lehman, Yong Zou, Maria S. Ortega, Caroline E. Maier, Jonathan M. Irish, Pierre P. Massion. Single cell mass cytometry analysis of human lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2911. doi:10.1158/1538-7445.AM2017-2911

Single cell analysis of human tissues and solid tumors with mass cytometry

BACKGROUND

Mass cytometry measures 36 or more markers per cell and is an appealing platform for comprehensive phenotyping of cells in human tissue and tumor biopsies. While tissue disaggregation and fluorescence cytometry protocols were pioneered decades ago, it is not known whether established protocols will be effective for mass cytometry and maintain cancer and stromal cell diversity.

METHODS

Tissue preparation techniques were systematically compared for gliomas and melanomas, patient derived xenografts of small cell lung cancer, and tonsil tissue as a control. Enzymes assessed included DNase, HyQTase, TrypLE, collagenase (Col) II, Col IV, Col V, and Col XI. Fluorescence and mass cytometry were used to track cell subset abundance following different enzyme combinations and treatment times.

RESULTS

Mechanical disaggregation paired with enzymatic dissociation by Col II, Col IV, Col V, or Col XI plus DNase for 1 h produced the highest yield of viable cells per gram of tissue. Longer dissociation times led to increasing cell death and disproportionate loss of cell subsets. Key markers for establishing cell identity included CD45, CD3, CD4, CD8, CD19, CD64, HLA-DR, CD11c, CD56, CD44, GFAP, S100B, SOX2, nestin, vimentin, cytokeratin, and CD31. Mass and fluorescence cytometry identified comparable frequencies of cancer cell subsets, leukocytes, and endothelial cells in glioma (R = 0.97), and tonsil (R = 0.98).

CONCLUSIONS

This investigation establishes standard procedures for preparing viable single cell suspensions that preserve the cellular diversity of human tissue microenvironments. © 2016 International Clinical Cytometry Society.

Role of epidermal primary cilia in the homeostasis of skin and hair follicles

Skin and hair follicle morphogenesis and homeostasis require the integration of multiple signaling pathways, including Hedgehog (Hh) and Wingless (Wnt), and oriented cell divisions, all of which have been associated with primary cilia. Although studies have shown that disrupting dermal cilia causes follicular arrest and attenuated Hh signaling, little is known about the role of epidermal cilia. Here, epidermal cilia function was analyzed using conditional alleles of the ciliogenic genes Ift88 and Kif3a. At birth, epidermal cilia mutants appeared normal, but developed basaloid hyperplasia and ingrowths into the dermis of the ventrum with age. In addition, follicles in the tail were disorganized and had excess sebaceous gland lobules. Epidermal cilia mutants displayed fewer long-term label-retaining cells, suggesting altered stem cell homeostasis. Abnormal proliferation and differentiation were evident from lineage-tracing studies and showed an expansion of follicular cells into the interfollicular epidermis, as is seen during wound repair. These phenotypes were not associated with changes in canonical Wnt activity or oriented cell division. However, nuclear accumulation of the ΔNp63 transcription factor, which is involved in stratification, keratinocyte differentiation and wound repair, was increased, whereas the Hh pathway was repressed. Intriguingly, the phenotypes were not typical of those associated with loss of Hh signaling but exhibited similarities with those of mice in which ΔNp63 is overexpressed in the epidermis. Collectively, these data indicate that epidermal primary cilia may function in stress responses and epidermal homeostasis involving pathways other than those typically associated with primary cilia.

An essential role for dermal primary cilia in hair follicle morphogenesis

The primary cilium is a microtubule-based organelle implicated as an essential component of a number of signaling pathways. It is present on cells throughout the mammalian body; however, its functions in most tissues remain largely unknown. Herein we demonstrate that primary cilia are present on cells in murine skin and hair follicles throughout morphogenesis and during hair follicle cycling in postnatal life. Using the Cre-lox system, we disrupted cilia assembly in the ventral dermis and evaluated the effects on hair follicle development. Mice with disrupted dermal cilia have severe hypotrichosis (lack of hair) in affected areas. Histological analyses reveal that most follicles in the mutants arrest at stage 2 of hair development and have small or absent dermal condensates. This phenotype is reminiscent of that seen in the skin of mice lacking Shh or Gli2. In situ hybridization and quantitative RT-PCR analysis indicates that the hedgehog pathway is downregulated in the dermis of the cilia mutant hair follicles. Thus, these data establish cilia as a critical signaling component required for normal hair morphogenesis and suggest that this organelle is needed on cells in the dermis for reception of signals such as sonic hedgehog.

The Oak Ridge Polycystic Kidney mouse: modeling ciliopathies of mice and men

The Oak Ridge Polycystic Kidney (ORPK) mouse was described nearly 14 years ago as a model for human recessive polycystic kidney disease. The ORPK mouse arose through integration of a transgene into an intron of the Ift88 gene resulting in a hypomorphic allele (Ift88Tg737Rpw). The Ift88Tg737Rpw mutation impairs intraflagellar transport (IFT), a process required for assembly of motile and immotile cilia. Historically, the primary immotile cilium was thought to have minimal importance for human health; however, a rapidly expanding number of human disorders have now been attributed to ciliary defects. Importantly, many of these phenotypes are present and can be analyzed using the ORPK mouse. In this review, we highlight the research conducted using the OPRK mouse and the phenotypes shared with human cilia disorders. Furthermore, we describe an additional follicular dysplasia phenotype in the ORPK mouse, which alongside the ectodermal dysplasias seen in human Ellis-van Creveld and Sensenbrenner's syndromes, suggests an unappreciated role for primary cilia in the skin and hair follicle.

Analysis of viral infection and viral and cellular DNA and proteins by flow cytometry

Viruses are obligate intracellular parasites that require the host cell replication, transcription, and translation machinery for reproduction. Each viral group provides a unique series of viral-cellular interactions. Studies have provided insight not only into viral replication and control of host functions, but also into cellular functions such as eukaryotic replication, transcription, and translation as well as the regulation of these events. This unit presents a protocol for flow cytometric monitoring of viral infection and quantitating viral-cellular events. The availability of monoclonal and/or polyclonal antibodies directed to both viral and cellular proteins offers the ability to assay a specific molecule in the intact fixed cell and the opportunity to correlate viral events with cellular processes such as progression through the cell cycle.

A subset of cells expressing SV40 large T antigen contain elevated p53 levels and have an altered cell cycle phenotype

Cells transformed by the simian virus 40 (SV40) large T antigen (Tag) contain elevated levels of cellular p53 protein. To quantify this relationship, levels of p53 were measured in NIH 3T3 cells that expressed different concentrations of Tag. Using immunoblotting, average p53 levels were shown to increase linearly with Tag concentrations in these cell lines. Single-cell measurements were also performed using flow cytometry to measure p53 immunofluorescence. Surprisingly, the flow cytometry experiments showed that two distinct cell populations, based on p53 content, were present in cells expressing high levels of Tag. One cell population contained elevated p53 levels. A second population did not contain elevated p53, even though high concentrations of Tag were present in the cells. This latter cell population did not appear to arise because of mutations in either Tag or p53. The two cell populations also had phenotypic differences. In exponentially growing cells, Tag alters the cell cycle distribution (decreases the percentage of G1 phase cells and increases the percentages of S and G2 + M phase cells). This phenotype was maximum in the cell population containing elevated p53. A lesser phenotype was found in the cell population that did not contain elevated p53. These data show, firstly, that cells can express significant levels of Tag and not contain elevated levels of p53 and, secondly, that elevated p53 correlates with the altered cell cycle distribution produced by Tag in growing cells.

Cognitive-behavioral stress management intervention decreases the prevalence of depression and enhances benefit finding among women under treatment for early-stage breast cancer

The authors tested effects of a 10-week group cognitive-behavioral stress management intervention among 100 women newly treated for Stage 0-II breast cancer. The intervention reduced prevalence of moderate depression (which remained relatively stable in the control condition) but did not affect other measures of emotional distress. The intervention also increased participants' reports that having breast cancer had made positive contributions to their lives, and it increased generalized optimism. Both remained significantly elevated at a 3-month follow-up of the intervention. Further analysis revealed that the intervention had its greatest impact on these 2 variables among women who were lowest in optimism at baseline. Discussion centers on the importance of examining positive responses to traumatic events--growth, appreciation of life, shift in priorities, and positive affect-as well as negative responses.

Cognitive-behavioral stress management intervention decreases the prevalence of depression and enhances benefit finding among women under treatment for early-stage breast cancer

The authors tested effects of a 10-week group cognitive-behavioral stress management intervention among 100 women newly treated for Stage 0-II breast cancer. The intervention reduced prevalence of moderate depression (which remained relatively stable in the control condition) but did not affect other measures of emotional distress. The intervention also increased participants' reports that having breast cancer had made positive contributions to their lives, and it increased generalized optimism. Both remained significantly elevated at a 3-month follow-up of the intervention. Further analysis revealed that the intervention had its greatest impact on these 2 variables among women who were lowest in optimism at baseline. Discussion centers on the importance of examining positive responses to traumatic events--growth, appreciation of life, shift in priorities, and positive affect-as well as negative responses.

Simian virus 40 induces multiple S phases with the majority of viral DNA replication in the G2 and second S phase in CV-1 cells

The infection of permissive monkey kidney cells (CV-1) with simian virus 40 induces G1 growth-arrested cells into the cell cycle. After completion of the first S phase and movement into G2, mitosis was blocked and the cells entered another DNA synthesis cycle (second S phase). Growth-arrested CV-1 cells replicated significant amounts of viral DNA in the G2 phase with the majority of synthesis occurring during the second S phase. When mimosine-blocked (G1/S) infected cells were released into the cell cycle, a major portion of the viral DNA was detected in G2 with the largest accumulation in the second S phase. The total DNA produced per infected cell was 10-12C with approximately 0.5-2C of viral DNA replicated per cell. Therefore the majority of the DNA per cell was cellular, 4C from the first S phase and approximately 4-6C from the second cellular synthesis phase.

SV40 small T antigen enhances progression to >G2 during lytic infection

The infection of monkey kidney (CV-1) cells with simian virus 40 (SV40) stimulates the cells into successive rounds of DNA synthesis without an intervening mitosis, leading to the acquisition of a >G2 DNA content. To elucidate the role of small t antigen in cell cycle progression and in viral replication during infection, studies were performed using an SV40 mutant (dl888) that lacks the ability to produce small t. Initially dl888-infected cells move through the first S phase at roughly the same rate as wild-type infected cells. Upon reaching G2, however, the dl888-infected cells progressed to >G2 at a reduced rate relative to wild-type. The slower rate of entry into >G2 of dl888-infected cells is associated with a decrease in total pRb and an increase in the ratio of hypophosphorylated to hyperphosphorylated pRb. The expression of cyclin D1 and p27(kip1) were elevated in dl888-infected cells compared to wild-type-infected CV-1 cells. Taken together, these results indicate that small t antigen plays a role in stimulating entry into >G2 in SV40-infected CV-1 cells, possibly by affecting the regulation of key cell cycle proteins.

Comparison of bone marrow extracellular matrices

We have compared the structure and composition of adult and fetal bovine bone marrow extracellular matrices. In contrast to fetal bone marrow, adult bone marrow has more oval fenestration and accumulation of adipocytes as well as lower protein content. These differences could be due to remodeling of bone marrow tissue as it develops. Zymogram analysis of matrix metalloproteinase (MMP) and tissue inhibitor of MMP (TIMP) activities showed that fetal, but not adult bone marrow extract contained a 96-kDa MMP and TIMP-1 and -2. These activities may contribute to the structural differences between adult and fetal bone marrow tissues.

Concerns about breast cancer and relations to psychosocial well-being in a multiethnic sample of early-stage patients

Much work on psychosocial sequelae of breast cancer has been guided by the assumption that body image and partner reaction issues are focal. In a tri-ethnic sample of 223 women treated for early-stage breast cancer within the prior year, the authors assessed a wider range of concerns and relations to well-being. Strongest concerns were recurrence, pain, death, harm from adjuvant treatment, and bills. Body-image concerns were moderate; concern about rejection was minimal. Younger women had stronger sexual and partner-related concerns than older women. Hispanic women had many stronger concerns and more disruption than other women. Life and pain concerns and sexuality concerns contributed uniquely to predicting emotional and psychosexual disruption; life and pain concerns and rejection concerns contributed to predicting social disruption. In sum, adaptation to breast cancer is a process bearing on several aspects of the patient's life space.

Concerns about breast cancer and relations to psychosocial well-being in a multiethnic sample of early-stage patients

Much work on psychosocial sequelae of breast cancer has been guided by the assumption that body image and partner reaction issues are focal. In a tri-ethnic sample of 223 women treated for early-stage breast cancer within the prior year, the authors assessed a wider range of concerns and relations to well-being. Strongest concerns were recurrence, pain, death, harm from adjuvant treatment, and bills. Body-image concerns were moderate; concern about rejection was minimal. Younger women had stronger sexual and partner-related concerns than older women. Hispanic women had many stronger concerns and more disruption than other women. Life and pain concerns and sexuality concerns contributed uniquely to predicting emotional and psychosexual disruption; life and pain concerns and rejection concerns contributed to predicting social disruption. In sum, adaptation to breast cancer is a process bearing on several aspects of the patient's life space.

Identification of SV40 T-antigen mutants that alter T-antigen-induced chromosome damage in human fibroblasts

The SV40 T antigen causes numerical (aneuploidy) and structural (aberrations) chromosome damage when expressed in human diploid fibroblasts. This chromosome damage precedes the acquisition of neoplastic traits such as anchorage independence, colony formation in reduced serum growth factors, immortalization, or tumorigenicity. Therefore, chromosome damage may be important in acquiring these traits because it could provide a mutational mechanism. To determine how the T antigen causes chromosome damage, point mutations were constructed that altered previously defined biochemical functions of the T protein. Mutant T antigen constructs were introduced into human diploid fibroblasts and selected by using G418. Clones of G418r cells that expressed mutant T antigens were expanded and scored for chromosome damage. Most of these mutant T antigens caused [corrected] levels of chromosome damage similar to those caused by [corrected] the wild-type T antigen. However, some T-antigen mutants induced fewer chromosome changes. A subset of these clones that induced less chromosome damage than wild-type T were examined further. Mutant T-antigen protein levels from this subset were quantified with flow cytometry and compared with wild-type protein expression levels. Mutations of T antigen shown previously to form less stable complexes with p53 caused less chromosome damage. A mutation in the zinc finger domain of T antigen also caused less chromosome damage. Interestingly, a mutant that caused loss of the ATPase activity of T antigen caused an increase in endoreduplicated cells. Also, a correlation was noted between cells expressing very low levels of T antigen (below detection limits when using flow cytometry) and an undamaged karyotype. This correlation indicates that there is a threshold level of T-antigen expression that induces chromosome damage and that expression levels on a per-cell basis rather than on a population basis should be considered in subsequent studies.

Activities of SV40 T antigen necessary for the induction of tetraploid DNA content in permissive CV-1 cells

To determine the role of SV40 T antigen in stimulating multiple rounds of DNA synthesis in permissive cells, CV-1 cells were transfected with plasmids expressing mutant or wt T antigen in the presence or absence of the SV40 origin of replication. Induction of cells with > G2 DNA content (tetraploid DNA content) and levels of T antigen protein were detected and analyzed by flow cytometry. The mutant T antigen proteins demonstrated the expected phenotypes as determined by immunoprecipitation. Elevated levels of T antigen protein were detected in each transfection, but full-length T antigen alone was responsible for the tetraploid DNA content. The studies show that full-length T antigen with point mutations to reduce binding to the cellular proteins p53 and/or Rb were capable of inducing > G2 DNA content though the induction by these mutants was greatly enhanced by the presence of the SV40 origin of replication. Truncated T antigen (aa 1-259) could induce cells with tetraploid DNA content only in the presence of the SV40 origin of replication and the absence of Rb binding. These studies suggest that multiple functions of T antigen are involved in the stimulation of the second round of cellular DNA synthesis.

Okadaic acid induces appearance of the mitotic epitope MPM-2 in SV40-infected CV-1 cells with a >G2-phase DNA content

Simian virus 40 (SV40) infection of quiescent monkey kidney cells stimulates two successive rounds of cellular DNA synthesis without an intervening mitosis. This uncoupling of S phase and mitosis indicates that SV40 modulates pathways regulating the G2-to-M phase transition. To examine the integrity of mitotic initiation pathways in infected cells that have bypassed mitosis, SV40-infected CV-1 cells were treated with okadaic acid (OA), a known inducer of premature mitosis in other cell types. OA treatment triggered the appearance of the mitotic marker MPM-2 in SV40-infected CV-1 cells progressing through either the first (diploid) or second (tetraploid) S phases. These results demonstrate that a subset of mitotic pathways are intact but inactive in SV40-infected cells that have bypassed mitosis and initiated tetraploid S phase.

Induction of tetraploid DNA content by mutant simian virus 40 T antigen that has reduced complex formation with p53

The 402 mutants (DE, DH, DN) of simian virus (SV) 40 form reduced levels of p53-T antigen complexes or no complexes in lytically infected cells (CV-1 cells) relative to wild-type (wt) virus when assayed by immunoprecipitation. When CV-1 cells were infected with the 402 mutants, the cells were induced into multiple rounds of DNA synthesis without mitosis, resulting in a large population of cells with > G2 (tetraploid) DNA content similar to wt virus. The levels of T antigen and p53 per cell that were determined by flow cytometry were similar to wt lytically infected cells, with the levels of T antigen increasing as the infection proceeded. The p53 increased as the levels of T antigen increased, similar to a wt infection. These studies demonstrate that, in lytically infected cells with reduced p53-T antigen complex formation, the cells are induced into multiple rounds of DNA synthesis.

Increase in total protein following infection of CV-1 cells with SV40 virus as assayed by flow cytometry

The changes in cell size and total protein were determined for G1-arrested, contact-inhibited CV-1 cells infected with Simian virus 40 (SV40). The assays used were the Biorad total protein assays (Bradford and DC protein assays) on a standard number of cells, total protein as assayed by fluorescein isothiocyanate (FITC) and SR101 by flow cytometry, orthoganol (90 degrees) light scatter by flow cytometry, and direct microscopic measurement with an ocular micrometer. Uninfected CV-1 cells and two cell lines with variations in DNA content (diploid vs. tetraploid) were used as controls for the studies presented. The results demonstrated a 40-60% increase in total protein at 32 to 42 h postinfection. These increases were similar to values obtained due to cellular changes resulting from viral replication and cell death.

Increased p53 protein associated with aging in human diploid fibroblasts

Molecular changes associated with cellular aging in a strain of human diploid fibroblasts, IMR-90, were addressed by analyzing the expression of the tumor suppressor protein, p53. In all studies, IMR-90 cultures were characterized as "young" or "near-senescent" based on morphology, rate of population doubling, capacity for DNA synthesis, and presence of established markers for senescence. When p53 was immunoprecipitated by monoclonal antibodies and detected by Western immunoblot analysis, more protein per cell was detected in the near-senescent cultures. A greater than 10-fold increase in p53 protein was measured with the PAb 1801 (N-terminal-specific) anti-p53 antibody, whereas PAb 122 (C-terminal-specific) measured a 5-fold increase. Although near-senescent cultures demonstrated a higher level of p53 than young cells, these cultures had similar charges and molecular weight p53 isoforms when analyzed by two-dimensional Western blots. When p53 RNA was compared to total RNA there was a decrease in p53 RNA with age, but on a per cell basis p53 RNA was elevated. These results provide evidence for transcriptional regulation of p53 during aging and support the hypothesis that elevated levels of p53 protein may play a role in cellular senescence.

DNA content distribution of mouse cells following infection with polyoma virus

Infection of primary to tertiary mouse embryo fibroblasts or mouse kidney cells with polyoma virus leads to stimulation of cellular DNA synthesis. When either confluent or growing mouse cells were infected, the monolayer cells were found to accumulate cells with a DNA content of S and G2/M phases of the cell cycle as assayed by flow cytometry. A similar pattern of DNA content was also observed in cells in the supernatant, which are probably cells replicating virus and dying. When compared with control cells, the infected monolayer and supernatant cells exhibited a population (5-27%) with a > G2 DNA content. The increase in DNA content of these > G2 cells was calculated to be an average of 26.7%, which is probably due to viral DNA. Polyoma contrasts with another papovavirus, SV40, which stimulates cells into DNA synthesis, with the majority of cells attaining a > G2/tetraploid DNA content, suggesting that there are differences in polyploidization between these two viruses.

Induction of tetraploid DNA content by simian virus 40 is dependent on T-antigen function in the G2 phase of the cell cycle

Previous experiments with the simian virus 40 mutant tsA357R-K (tsA30) demonstrated a T-antigen function that is required for production of cells with a greater-than-G2-phase DNA content. In this study, temperature shift experiments indicated that the temperature-sensitive function of tsA357R-K, which is necessary for entry into the greater-than-G2 phase, is not required in G1 or S but must be supplied in the G2 phase.

Simian virus 40 prevents activation of M-phase-promoting factor during lytic infection

Simian virus 40 (SV40) infection stimulates confluent cultures of monkey kidney cells into successive rounds of cellular DNA synthesis without intervening mitosis. As an initial step in defining the mechanisms responsible for viral inhibition of mitosis, M-phase-promoting factor (MPF) was examined in SV40-infected CV-1 cells passing from G2 phase into a second S phase. MPF is a serine-threonine protein kinase that is essential for mitosis in eukaryotic cells. In SV40-infected cells exiting G2 phase, there was a reduced amount of MPF-associated H1 kinase activity relative to that of uninfected cells passing through mitosis. Both subunits of MPF, cyclin B and the p34cdc2 catalytic subunit, were present and in a complex in infected cells. In uninfected cultures, passage through mitosis was associated with the dephosphorylation of the p34cdc2 subunit, which is characteristic of MPF activation. In contrast, the p34cdc2 subunit remained in the tyrosine-phosphorylated, inactive form in SV40-infected cells passing from G2 phase into a second S phase. These results suggest that although the MPF complex is assembled and modified normally, SV40 interferes with pathways leading to MPF activation.

A new perspective on threatened autonomy in elderly persons: the disempowering process

This study explored factors other than medical condition and treatments which contributed to the discharge experiences of 12 rural and 9 urban patients. Interpretive research methodology included document review, observation and in-depth interviews of all key participants. The purposefully selected sample consisted of a total of 21 patients, 22 informal caregivers, and 117 professionals involved in the hospital and/or home setting. Findings document a new perspective on how patients and professionals together contribute to the patient's threatened autonomy. Lack of clarity about goals, aspirations, and purpose in life and a generally negative frame of mind in the elderly combine with professional practice approaches to create a disempowering process. Faced with the biomedical orientation and paternalism of professionals, patients with a positive mindset and sense of direction and purpose in life did not experience threat to their autonomy. The researchers conclude that empowerment strategies must encompass a patient-centred approach, which includes an understanding of the patient's mindset, goals, aspirations, and sense of purpose within a larger life context. This consideration is essential to enable elderly patients to maintain autonomy despite continued health care requirements.

Hypophosphorylated retinoblastoma gene product accumulates in SV40-infected CV-1 cells acquiring a tetraploid DNA content

Simian virus 40 (SV40) infection of monkey kidney cells induces successive rounds of cellular DNA synthesis without intervening mitosis. To gain an understanding of the mechanisms responsible for disruption of cell cycle control during lytic infection, pRB phosphorylation and cell cycle distribution were examined following SV40 infection of CV-1 cells. The hypophosphorylated pRB present in confluent CV-1 cells was phosphorylated within 14 h following SV40 infection. Phosphorylated pRB then remained the predominant form as cells progressed from late G1 through S phase. Hypophosphorylated pRB reappeared as cells moved through G2 and acquired a tetraploid (> G2) DNA content. The reappearance of hypophosphorylated pRB in a population with decreasing numbers of cells in G1 phase and increasing numbers of cells in > G2 suggests that accumulation of hypophosphorylated pRB may be involved in T antigen-induced tetraploidy.

Polyomavirus enhancer requirements for expression in embryonal carcinoma cells

Wild type polyomavirus expression is suppressed in embryonal carcinoma (EC) cell lines. This suppression is alleviated when the EC cells are induced to differentiate. Several characterized host range mutants of polyoma overcome suppression and are able to express and replicate in the undifferentiated EC cells. These previously described isolates were obtained by serial passage of a wild type strain through PCC4 or F9 EC lines. We present a new pyPCC4 isolate (LPT) derived without selection in EC cells. Isolates with host range specificity for a given EC line have been reported to share several common rearrangements and features. These features are also observed in LPT. We report a novel feature shared by these mutants, including LPT, capable of expression in the EC cell line PCC4. In 8 of 10 isolates a novel sequence is created within the enhancer region by rearrangement junctions with near perfect homology to the AP-1 core consensus sequence, 'TGACT(C/A)A'. That the precise location of these junctions varies among these isolates suggest a functional role for this conserved sequence. Our goal is to understand the function of various mutations in host range mutants of polyoma. In order to understand the rearrangements necessary for expression and replication of polyoma in PCC4 cells, we have further characterized the limits of the B enhancer in these cells as compared to those described in permissive cell systems. We have been able to locate the origin proximal limit of the B enhancer for replication close to nt 5189 and distinguish it from the origin proximal limit of the B enhancer for transcription near nt 5215. The two B enhancer cores overlap but do not coincide and are conserved in both cell lines.

Quantitation of simian virus 40 T-antigen correlated with the cell cycle of permissive and non-permissive cells

These studies examined cell cycle progression and quantitative changes in T-antigen following infection by SV40. Single cells were assayed by multiparameter flow cytometric analysis (FCM) for DNA content and T-antigen expression. Conditions were used which permitted permissive, semi-permissive, and non-permissive cells to be monitored through two rounds of DNA synthesis induced by SV40. The permissive cells included the monkey kidney cell lines; CV-1, Vero and BSC-1 and the COS-1 and COS-7 which are CV-1 cells transformed with an origin defective SV40. The non-permissive cell strains included mouse embryo fibroblasts, Chinese hamster fibroblasts, and IMR-90, a human diploid fibroblast. Cell types differed in the maximal amount of T-antigen expressed per cell. Additionally, all cell types expressed a limited quantity of T-antigen for each cell cycle phase and the quantity increased in each successive phase. The level in each phase was increased only two-fold when 100 times more virus was used. Thus, for an infected population the quantity of T-antigen was dependent on cell cycle distribution. High levels of T-antigen were not required for permissive infection; however, permissive cells were distinguished from non-permissive cells by the G2 levels. Permissive G2 cells had more than double the T-antigen content expressed in G1, while nonpermissive G2 cells had less than a two-fold increase over G1 levels. The appearance of cells with tetraploid DNA content and the failure to undergo mitosis correlated to the higher T-antigen levels in the G2 of the permissive cells. Two other strains of SV40, 776, and VA45 exhibit similar values for T-antigen expression and movement into tetraploid DNA content. This study establishes the levels of T-antigen correlated to the cell cycle and cell type.

Altered DNA/protein complexes specific for the beta-interferon regulatory region observed in murine embryonal carcinoma F9 cells

Murine embryonal carcinoma (EC) F9 cells do not produce interferon (IFN) at the protein or RNA level in response to inducing agents, while retinoic acid differentiated F9 cells do produce IFN. A probe was constructed spanning positions -104 to -39 of the human beta-IFN upstream regulatory region to examine this developmental control at the level of a transcriptional regulatory mechanism. Gel mobility shift analyses were used to examine this molecular mechanism to determine whether the differential expression of positive or negative trans-acting factors may act to control beta-IFN expression in undifferentiated EC cells. These analyses showed that while nuclear extracts from poly-I,C induced L929 cells, in the IFN producing cell line, showed two shifted bands, nuclear extracts from both induced and uninduced F9 cells showed only one shifted band using the -104/-39 probe. While this single shifted band co-migrated with the faster migrating species of L929 cell extracts, competition analysis revealed differences between the two complexes. An oligonucleotide representing the positive regulatory domain PRDII competed efficiently for the probe when induced F9 cell extracts were examined, but failed to compete when induced L929 cell extracts were examined. In contrast, an oligonucleotide representing the positive regulatory domain PRDI competed very well when induced L929 cell extracts were examined but had only a minimal effect when induced F9 cell extracts were examined. These data suggest the involvement of developmentally regulated transcriptional factor(s) which have yet to be characterized.

Simian virus 40 large T-antigen function is required for induction of tetraploid DNA content during lytic infection

Infection of quiescent CV-1 cells with simian virus 40 mutant tsA30 at 37 degrees C resulted in the induction of two rounds of cellular DNA synthesis in T-antigen-positive cells, as previously described for wild-type simian virus 40. Following infection with tsA30 at 40.5 degrees C, T-antigen-positive cells were induced into S phase and reached a diploid G2 DNA content; however, a second S phase was not initiated. The failure of tsA30-infected CV-1 cells to enter tetraploid S phase at 40.5 degrees C identifies a T-antigen function, distinct from T-antigen functions responsible for stimulation of cell DNA synthesis, which is required for initiation of a second round of DNA synthesis without mitosis.

[Laparoscopic cholecystectomy]

The standard treatment for cholelithiasis is cholecystectomy at open operation, which requires relatively long hospitalization and long absence from work. These socio-economic factors and a desire to avoid operative trauma and its complications led to the development of noninvasive therapy. The methods used so far, stone dissolution and extracorporeal shock wave lithotripsy, have proven unsatisfactory. The first takes a long time and has a high recurrence rate, the second has relatively frequent complications. Furthermore, both methods leave the diseased gallbladder in place. During the past year laparoscopic cholecystectomy has been developed in various centers and has been adopted in our department. We describe our initial experience with the technique in 70 cases aged 18-79 years.

T antigen and p53 in pre- and post-crisis simian virus 40-transformed human cell lines

Infection of normal human diploid fibroblasts (HF) with the DNA tumor virus simian virus 40 (SV) leads to an extension of lifespan and concomitant increase in the levels of the viral large tumor antigen (T antigen) and the cellular protein p53. The intracellular localization of T antigen and p53 was mostly nuclear in both SVpre-crisis and SVpost-crisis cells, however certain population doubling (PD) of the SVpre-crisis cells exhibited some cytoplasmic staining. The DNA content of SVpre-crisis cells shifted to tetraploidy and the SVpost-crisis cells were near-tetraploid. Quantitation of T antigen and p53 in single cells by flow cytometry demonstrated that for all antibodies tested the levels of T antigen were higher in the SVpre-crisis HF than in the SVpost-crisis. The quantity of p53 increased with increasing age of SVpre-crisis HF, and the levels of p53 were higher in the SVpost-crisis HF populations. Immunoprecipitation of p53, T antigen and complexes demonstrated that all p53 was bound to T antigen in SVpre-crisis HF and SVpost-crisis HF. The SVpre-crisis HF cells showed that 33% of all T antigen was bound to p53, while 67% was free, and the SVpost-crisis HF exhibited 50% free T antigen and 50% bound to p53. The half-life of p53 was similar in all SVpre-crisis HF; however, the half-life was 2-3 times greater in SVpost-crisis HF than in SVpre-crisis HF. These results suggest that the interaction of DNA (ploidy), T antigen, p53 and complexes may be involved in formation of a stable SV40-transformed human cell line.

A morphological and phenotypic analysis of Walker 256 cells

A detailed morphological analysis of Walker 256 cells sensitive and resistant to cis-diamminedichloroplatinum(II) has been performed. Two cell populations are identified by electron microscopy of differing differentiation corresponding structurally to cells reported in experimentally induced metastases. Phenotyping of the cells using a number of monoclonal antibodies by immunocytochemistry and flow cytometry showed the absence of epithelial cell markers: however, the cells stained intensely for markers for germ and/or hematopoietic cells. Further studies utilizing monoclonal antibodies to lymphoid, myeloid, and monocytoid cells showed the cells to be monocytoid in origin. No evidence of cell heterogeneity was evident from the phenotypic experiments (a biphasic pattern was not observed). Enzyme histochemistry showed strong focal acid phosphatase activity suggestive of cells of hematopoietic origin. Thus the concept that these cells reflect an epithelial cell of origin is not substantiated by phenotyping with two methodologies.