Regulation of intestinal myofibroblasts by KRas-mutated colorectal cancer cells through heparin-binding epidermal growth factor-like growth factor

Abstract

In colorectal cancer, gain-of-function mutations in KRas play a critical role in malignant transformation. Tumor growth in colorectal cancer is known to be promoted by the intestinal myofibroblasts (IMFs) that localize adjacent to the cancer cells, but the mechanisms of interaction between KRas-mutated cancer cells and the myofibroblasts remain unclear. Here, we investigated the effects of KRas-mutated cells on the behavior of myofibroblasts by using mouse primary IMFs and cells of an IMF cell line (LmcMF) and a mouse colon epithelial cell line (aMoC1). Conditioned medium (CM) was collected from aMoC1 cells overexpressing a control vector or KRasV12 vector (KRasV12-CM), and the effects of KRasV12-CM on IMFs were analyzed by performing proliferation assays, wound-healing assays, Boyden chamber assays, and western blotting. Whereas KRasV12-CM exerted little effect on the differentiation and proliferation of primary IMFs, the CM promoted migration of both primary IMFs and LmcMF cells. In KRasV12-overexpressing aMoC1 cells, mRNA expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF) was higher than in mock-transfected aMoC1 cells, and HB-EGF promoted the migration of primary IMFs and LmcMF cells. Moreover, KRasV12-CM-induced IMF migration was suppressed by dacomitinib, an inhibitor of HB-EGF receptors. Notably, in LmcMF cells, both KRasV12-CM and HB-EGF activated extracellular signal-regulated kinase (ERK) and c-jun N-terminal kinase (JNK), whereas KRasV12-CM-induced migration of IMFs was suppressed following treatment with either an ERK inhibitor (FR180204) or a JNK inhibitor (SP600125). These results suggest that HB-EGF secreted from KRas-mutated colorectal cancer cells promotes IMF migration through ERK and JNK activation, which, in turn, could support cancer progression.

Ligand-Independent Epidermal Growth Factor Receptor Overexpression Correlates with Poor Prognosis in Colorectal Cancer

“…For HBEGF, a pivotal role in cancer progression has been proposed in various cancers, including cervical, breast, and gastric cancers [ 20 - 23 ]. In CRC, Kawasaki et al [ 24 ] suggested that HBEGF has roles in CRC progression through the recruitment of intestinal myofibroblasts. In our cohort, although HBEGF expression is commonly detected in CRC, we were unable to determine a significant correlation with various clinicopathologic factors except for tumor differentiation.…”

KRAS Oncogenic Signaling Extends beyond Cancer Cells to Orchestrate the Microenvironment

“…Recently, it was shown that the conditioned medium of KRASV12overexpressing colorectal cells strongly increased migration of intestinal fibroblasts without affecting their proliferation rate and their differentiation status. The observed effect was found to be mediated by the heparin-binding EGF-like growth factor (HB-EGF) upregulated by KRAS-mutated cells and activation of HB-EGF receptors, and ERK 1/2 and JNK signals in fibroblasts (70).…”

JNK, p38, ERK, and SGK1 Inhibitors in Cancer

“…The IC50 for ERK1 = 0.14 μM and for ERK2 = 0.31 μM. FR180204 attenuates mesothelioma cell proliferation [ 71 ], decreases cell viability colorectal cancer cell lines [ 72 ], decreases cell proliferation and increases apoptosis in colorectal cancer cells in combination with AKT inhibitor API-1 [ 73 ], and inhibits intestinal myofibroblast migration induced by KRAS-mutated colorectal cancer cells [ 74 ]. This inhibitor is also used in arthritis research [ 75 ].…”