Hematopoietic transcription factor GFI1 promotes anchorage independence by sustaining ERK activity in cancer cells
Hao Wang, … , Zhenyi Ma, Zhe Liu
Hao Wang, … , Zhenyi Ma, Zhe Liu
Published July 12, 2022
Citation Information: J Clin Invest. 2022;132(17):e149551. https://doi.org/10.1172/JCI149551.
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Research Article Cell biology Oncology

Hematopoietic transcription factor GFI1 promotes anchorage independence by sustaining ERK activity in cancer cells

Abstract

The switch from anchorage-dependent to anchorage-independent growth is essential for epithelial metastasis. The underlying mechanism, however, is not fully understood. In this study, we identified growth factor independent-1 (GFI1), a transcription factor that drives the transition from adherent endothelial cells to suspended hematopoietic cells during hematopoiesis, as a critical regulator of anchorage independence in lung cancer cells. GFI1 elevated the numbers of circulating and lung-infiltrating tumor cells in xenograft models and predicted poor prognosis of patients with lung cancer. Mechanistically, GFI1 inhibited the expression of multiple adhesion molecules and facilitated substrate detachment. Concomitantly, GFI1 reconfigured the chromatin structure of the RASGRP2 gene and increased its expression, causing Rap1 activation and subsequent sustained ERK activation upon detachment, and this led to ERK signaling dependency in tumor cells. Our studies unveiled a mechanism by which carcinoma cells hijacked a hematopoietic factor to gain anchorage independence and suggested that the intervention of ERK signaling may suppress metastasis and improve the therapeutic outcome of patients with GFI1-positive lung cancer.

Authors

Hao Wang, Zhenzhen Lin, Zhe Nian, Wei Zhang, Wenxu Liu, Fei Yan, Zengtuan Xiao, Xia Wang, Zhenfa Zhang, Zhenyi Ma, Zhe Liu

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Figure 2

GFI1 promotes cell detachment and anchorage independence.

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GFI1 promotes cell detachment and anchorage independence. (A) Immunoblot...
(A) Immunoblot showing expression of GFI1 and ACTB. See complete unedited blots in the supplemental material. (B) Phase-contrast micrographs of GFI1-expressing A549 and GFI1-KO H1155 cells. Scale bars: 40 μm. (C) GFI1-expressing A549 cells or GFI1-KO H1155 cells were plated on fibronectin-coated, laminin332-coated, or collagen I–coated plates. After 15 minutes, attached cells were counted. Scale bars: 200 μm. Bar graph shows the number of adherent cells. Mean ± SD represents 10 visualized areas in 1 experiment. Three independent experiments were performed. ****P < 0.0001 (unpaired 2-tailed Student’s t test). (D) The cell death of GFI1-expressing A549 cells and GFI1-KO H1155 cells was assessed after 24 hours under attached or floating condition. Mean ± SD represents 3 replicates in 1 experiment. Three independent experiments were performed. ****P < 0.0001 (1-way ANOVA test with post hoc contrasts by Tukey’s test). (E) A549 and GFI1-expressing A549 cells were forced into suspension for 48 hours and transcriptional profiles were measured using RNA-Seq. Gene set enrichment analysis showing the top 10 downregulated pathways in GFI1-expressing cells versus control A549 cells. (F) A549, GFI1-expressing A549, H1155, and GFI1-KO H1155 cells were cultured in Matrigel for 8 days. Confocal midpoint slices of acinus stained for ITGB1, laminin V, and DAPI are shown. Colonies greater than 50 μm in diagram were counted. Scale bars: 50 μm. Mean ± SD represents 10 visualized areas in 1 experiment. Three independent experiments were performed. Data shown as mean ± SEM. ****P < 0.0001 (unpaired 2-tailed Student’s t test). (G) Indicated cells were allowed to grow in soft agar for 2 weeks, and colonies were counted. Data shown as mean ± SD for a representative experiment performed in triplicate. Three independent experiments were performed.