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J.M. Poczobutt
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ORAL 41 - Immune Biology, Microenvironment and Novel Targets (ID 159)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:S.K. Padda, R. Nemenoff
- Coordinates: 9/09/2015, 18:30 - 20:00, Four Seasons Ballroom F1+F2
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ORAL41.06 - Transcriptional Profiling of Distinct Macrophage Subsets in Lung Tumor Microenvironment Reveals Their Functional Heterogeneity (ID 3181)
19:24 - 19:35 | Author(s): J.M. Poczobutt
- Abstract
Background:
Lung cancer is the leading cause of cancer-related deaths in both men and women. While extensive research has focused on genetic mutations in neoplastic epithelial cells, it has now become apparent that cancer progression and metastasis involve complex interactions between cancer cells and the cells of the tumor microenvironment. Myeloid cells of mononuclear phagocyte lineage are a significant component of the tumor microenvironment in lung cancer. Depending on the activation state, myeloid cells have been implicated in tumor – promoting processes such angiogenesis, tissue remodeling and immunosuppression, but also in anti-tumor immunity such as supporting immune surveillance and direct cytotoxicity. The goal of this study was to identify distinct populations of monocyte/macrophage cells and to gain insight into their functions through transcriptional profiling.
Methods:
We used an orthotopic immunocompetent mouse model, in which Lewis Lung carcinoma cells, a cell line derived from mouse adenocarcinoma, were injected directly into the left lung lobe of syngeneic C57BL/6 mice. Whole left lung lobes bearing primary tumors were harvested at 2 and at 3 weeks after cancer cell injection, together with lungs from uninjected mice. Tissues were processed into single-cell suspensions and analyzed by multi-color flow cytometry. The flow cytometry strategy employed a combination of myeloid specific surface markers such as CD11b, CD11c, CD64, and SiglecF to identify distinct monocyte/macrophage subpopulations. We recovered these cell populations by flow cytometry-based cell sorting, isolated RNA, and performed transcriptional profiling by RNA-seq. Sequencing data were analyzed by TopHat/Cufflinks/CuffDiff software package and EdgeR. To define the lineage of the isolated cells we correlated their transcriptional profiles to published profiles of immune cells from blood and lung of naïve mice. Further, we used hierarchical clustering and web-based bioinformatic pathway analysis tool to discover functions and pathways enriched in specific myeloid populations.
Results:
Based on the combination of myeloid markers and transcriptional profiling, we identified 4 distinct populations of monocyte/macrophage cells: MacA, which represent alveolar macrophages, MacB1, which represent a mixture of dendritic cells and Ly6C- monocytes, MacB2, which represent Ly6C+ monocytes, and MacB3, which represent interstitial/infiltrating macrophages. While the numbers of MacA and MacB1 remain unchanged with cancer progression, MacB2 and MacB3 expand rapidly. Pathway analysis indicated that each population of cells regulates distinct functions in the tumor microenvironment, such as lipid metabolism, cytokine or chemokine secretion, production and remodeling of extracellular matrix, antigen presentation.
Conclusion:
These data provide critical insights into the heterogeneous nature and diverse functions of myeloid cells in tumor microenvironment of lung cancer. This study has the potential for development of therapeutics that target specific subsets of myeloid cells that could complement conventional cancer-cell-targeted therapies.
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P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.04-056 - Use of Pooled shRNA Synthetic Lethal Screens within an In Vivo Murine Model to Identify Microenvironment-Dependent Lung Cancer Genes (ID 3140)
09:30 - 09:30 | Author(s): J.M. Poczobutt
- Abstract
Background:
Lung cancer remains the leading cause of cancer-related deaths worldwide. While significant knowledge has been gained regarding the characterization of mutational drivers in NSCLC, much less is known regarding interactions between tumor cells and the surrounding microenvironment that are critical for tumor progression. Additionally, a significant limitation in current understanding is the lack of knowledge regarding which tumor gene products are necessary for promoting cell survival in the context of the tumor microenvironment. We hypothesize that the use of pooled shRNA synthetic lethal screens within an in vivo murine model will allow for the elucidation of targetable microenvironment-dependent genes.
Methods:
We generated a custom murine shRNA lentiviral library targeting 250 genes implicated in the communication between cancer cells and the microenvironment, which was used to transduce two murine cell lines: Lewis Lung carcinoma (LLC) and CMT167 cells. Following puromycin selection of cells harboring incorporated shRNA’s of interest, populations were expanded and designated for in vitro versus in vivo replication and growth. Selected cells were allocated to either in vitro passage vs direct in vivo injection into the lungs of 18 week-old syngeneic C57BL6 mice. After 4 weeks, cells were harvested and gDNA was isolated. Sequencing and quantitation of shRNA was performed using an Illumina deep-sequencing platform. Both raw and normalized read counts were assessed and analyzed to determine the relative representation of a particular shRNA within an in vitro or in vivo sample. Following quality control assessments which demonstrated adequate read count numbers per sample, and appropriate correlation of sample similarity per groups, direct comparisons between in vitro and in vivo samples were performed.
Results:
Multiple gene candidates were identified and largely reproducible via either rank analysis, mean, or t-test analyses. Candidate genes included multiple chemokines, and their receptors, matrix proteases, complement factors, and growth factor receptors.
Conclusion:
These results suggest a list of genes that are both intriguing and diverse, pointing toward gene products that would not have been previously predicted to influence cancer cell survival and growth through a lung cancer cell-autonomous fashion. Furthermore, these genes appear to potentially interact with multiple compartments of the tumor microenvironment including the extracellular matrix, cytokine milieu, vascular structures (complement factors), and the adaptive immune system. Validation of specific gene targets are ongoing through assessment of tumor growth comparing murine cell lines transfected with individual shRNA’s of interest vs control tumor cells. Furthermore, parallel pooled shRNA synthetic lethal screens within selectively adaptive immune-deficient models are currently in progress.
