LKB1 loss promotes endometrial cancer progression via CCL2-dependent macrophage recruitment
Christopher G. Peña, … , Rolf A. Brekken, Diego H. Castrillon
Christopher G. Peña, … , Rolf A. Brekken, Diego H. Castrillon
Published September 28, 2015
Citation Information: J Clin Invest. 2015;125(11):4063-4076. https://doi.org/10.1172/JCI82152.
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Research Article Oncology

LKB1 loss promotes endometrial cancer progression via CCL2-dependent macrophage recruitment

Abstract

Endometrial cancer is the most common gynecologic malignancy and the fourth most common malignancy in women. For most patients in whom the disease is confined to the uterus, treatment results in successful remission; however, there are no curative treatments for tumors that have progressed beyond the uterus. The serine/threonine kinase LKB1 has been identified as a potent suppressor of uterine cancer, but the biological modes of action of LKB1 in this context remain incompletely understood. Here, we have shown that LKB1 suppresses tumor progression by altering gene expression in the tumor microenvironment. We determined that LKB1 inactivation results in abnormal, cell-autonomous production of the inflammatory cytokine chemokine (C-C motif) ligand 2 (CCL2) within tumors, which leads to increased recruitment of macrophages with prominent tumor-promoting activities. Inactivation of Ccl2 in an Lkb1-driven mouse model of endometrial cancer slowed tumor progression and increased survival. In human primary endometrial cancers, loss of LKB1 protein was strongly associated with increased CCL2 expression by tumor cells as well as increased macrophage density in the tumor microenvironment. These data demonstrate that CCL2 is a potent effector of LKB1 loss in endometrial cancer, creating potential avenues for therapeutic opportunities.

Authors

Christopher G. Peña, Yuji Nakada, Hatice D. Saatcioglu, Gina M. Aloisio, Ileana Cuevas, Song Zhang, David S. Miller, Jayanthi S. Lea, Kwok-Kin Wong, Ralph J. DeBerardinis, Antonio L. Amelio, Rolf A. Brekken, Diego H. Castrillon

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Figure 3

Conditional Lkb1 knockout in murine endometrial epithelium results in endometrial cancers characterized by high CCL2 production.

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Conditional Lkb1 knockout in murine endometrial epithelium results in en...
All experiments were conducted in conditional knockout Lkb1–/– and sibling control Lkb1+/+ female mice at 12 weeks of age, the time point at which myometrial invasion first occurs in this well-characterized model. Tissues were harvested at proestrus. (A) ELISA of serum or uterine protein lysates showing a significant increase of CCL2 levels following Lkb1 deletion (n = 14 Lkb1+/+, n = 24 Lkb1–/–). (B) CCL2 levels in tumor lysates (per ELISA) plotted against tumor mass from Lkb1–/– animals, showing a direct correlation between tumor mass and CCL2 levels (n = 24 mice, Pearson coefficient r2 = 0.39 with P = 0.001 per 2-tailed t test). (C) CCL2 expression in endometrial epithelium by image analysis (regions analyzed correspond to those enclosed by dashed lines in the next panel). Tissue sections were stained with a validated CCL2 antibody, and green CCL2 signal quantitation was performed using ImageJ (http://imagej.nih.gov/ij/) (n = 6 animals per experiment). Expression was normalized to the background signal present in Ccl2–/–; Lkb1+/+ uterine epithelium. (D) CCL2 immunofluorescence of uterine tissue sections. s, stroma; e, epithelium. Asterisks denote basal CCL2 expression. Two different regions are shown for each genotype. (E) LKB1 and pAMPK (Thr172) immunohistochemistry of uterine tissue sections from Lkb1+/+ and Lkb1–/– mice. As expected, Lkb1 deletion in endometrial epithelium resulted in undetectable LKB1 protein as well as reduced pAMPK compared with control siblings. Statistical significance in A and C was determined by Student’s t test. *P < 0.005; **P < 0.001. Scale bars: 50 μm. Error bars = SEM.