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Effects of Beclin 1 overexpression on aggressive phenotypes of colon cancer cells.

ABSTRACT: Beclin 1 is involved in autophagy, differentiation, apoptosis and cancer progression, and functions as a haploinsufficient tumor suppressor gene. The aim of the present study was to elucidate the function of Beclin 1 in colon cancer. A Beclin 1-expressing plasmid was transfected into HCT-15 and HCT-116 cells, and the phenotypes and associated molecules were determined. Beclin 1 transfectants were subcutaneously injected into nude mice to determine tumor growth, and proliferation and apoptosis levels using Ki-67 immunostaining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), respectively. Beclin 1 overexpression inhibited viability as determined using a Cell Counting Kit-8 assay, inhibited migration and invasion as determined using a wound healing assay or Transwell assay, and lamellipodia formation by filamentous actin staining, induced autophagy as determined using electron microscopy, and light chain 3B (LC-3B) expression, and apoptosis as determined using Annexin V staining in the two cell lines (P<0.05). Beclin 1 induced G2 arrest of HCT-15 transfectants as determined using propidium iodide staining (P<0.05), whereas HCT-116 transfectants were arrested in G1 phase (P<0.05). The two transfectants exhibited increased expression of c-Myc, cyclin D1, ?-catenin, insulin-response element 1 and 78 kDa glucose-regulated protein compared with the control and mock cells as determined using the reverse transcription-quantitative polymerase chain reaction (P<0.05). Beclin 1 overexpression upregulated LC-3B and cyclin-dependent kinase 4 expression, but downregulated cyclin E expression of the cancer cell lines as determined using western blot analysis (P<0.05). Beclin 1 expression in vivo significantly suppressed the proliferation of colon cancer cells in xenograft models via inducing apoptosis by TUNEL, and inhibiting proliferation by Ki-67 expression (P<0.05). Beclin 1 overexpression may reverse aggressive phenotypes and suppress colon cancer tumor growth, and be employed as a target molecule for gene therapy of patients with colon cancer.

SUBMITTER: Zhang MY

PROVIDER: S-EPMC6341844 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Effects of Beclin 1 overexpression on aggressive phenotypes of colon cancer cells.

Zhang Mei-Ying MY Wang Li-Yuan LY Zhao Shuang S Guo Xiao-Chong XC Xu Ying-Qi YQ Zheng Zhi-Hong ZH Lu Hang H Zheng Hua-Chuan HC

Oncology letters 20181210 2

Beclin 1 is involved in autophagy, differentiation, apoptosis and cancer progression, and functions as a haploinsufficient tumor suppressor gene. The aim of the present study was to elucidate the function of Beclin 1 in colon cancer. A Beclin 1-expressing plasmid was transfected into HCT-15 and HCT-116 cells, and the phenotypes and associated molecules were determined. Beclin 1 transfectants were subcutaneously injected into nude mice to determine tumor growth, and proliferation and apoptosis le ...[more]

PMID: 30675309

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Project description:BackgroundPoor prognosis in colon cancer is associated with a high content of cancer-associated fibroblasts (CAFs) and an immunosuppressive tumor microenvironment. The relationship between these two features is incompletely understood. Here, we aimed to generate a model system for studying the interaction between cancer cells and CAFs and their effect on immune-related cytokines and T cell proliferation.MethodsCAFs were isolated from colon cancer liver metastases and were immortalized to prolong lifespan and improve robustness and reproducibility. Established medium and matrix compositions that support the growth of patient-derived organoids were adapted to also support CAF growth. Changes in growth pattern and cellular re-organization were assessed by confocal microscopy, live cell imaging, and immunofluorescence. Single cell RNA sequencing was used to study CAF/organoid co-culture-induced phenotypic changes in both cell types. Conditioned media were used to quantify the production of immunosuppressive factors and to assess their effect on T cell proliferation.ResultsWe developed a co-culture system in which colon cancer organoids and CAFs spontaneously organize into superstructures with a high capacity to contract and stiffen the extracellular matrix (ECM). CAF-produced collagen IV provided a basement membrane supporting cancer cell organization into glandular structures, reminiscent of human cancer histology. Single cell RNA sequencing analysis showed that CAFs induced a partial epithelial-to-mesenchymal-transition in a subpopulation of cancer cells, similar to what is observed in the mesenchymal-like consensus molecular subtype 4 (CMS4) colon cancer. CAFs in co-culture were characterized by high expression of ECM components, ECM-remodeling enzymes, glycolysis, hypoxia, and genes involved in immunosuppression. An expression signature derived from CAFs in co-culture identified a subpopulation of glycolytic myofibroblasts specifically residing in CMS1 and CMS4 colon cancer. Medium conditioned by co-cultures contained high levels of the immunosuppressive factors TGFβ1, VEGFA and lactate, and potently inhibited T cell proliferation.ConclusionCo-cultures of organoids and immortalized CAFs recapitulate the histological, biophysical, and immunosuppressive features of aggressive mesenchymal-like human CRC. The model can be used to study the mechanisms of immunosuppression and to test therapeutic strategies targeting the cross-talk between CAFs and cancer cells. It can be further modified to represent distinct colon cancer subtypes and (organ-specific) microenvironments.

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Effects of Beclin 1 overexpression on aggressive phenotypes of colon cancer cells.

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Effects of Beclin 1 overexpression on aggressive phenotypes of colon cancer cells.

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