Macrophages Enhance Migration in Inflammatory Breast Cancer Cells via RhoC GTPase Signaling

Abstract

Inflammatory breast cancer (IBC) is the most lethal form of breast cancer. All IBC patients have lymph node involvement and one-third of patients already have distant metastasis at diagnosis. This propensity for metastasis is a hallmark of IBC distinguishing it from less lethal non-inflammatory breast cancers (nIBC). Genetic profiling studies have been conducted to differentiate IBC from nIBC, but no IBC cancer-cell-specific gene signature has been identified. We hypothesized that a tumor-extrinsic factor, notably tumor-associated macrophages, promotes and contributes to IBC’s extreme metastatic phenotype. To this end, we studied the effect of macrophage-conditioned media (MCM) on IBC. We show that two IBC cell lines are hyper-responsive to MCM as compared to normal-like breast and aggressive nIBC cell lines. We further interrogated IBC’s hyper-responsiveness to MCM using a microfluidic migration device, which permits individual cell migration path tracing. We found the MCM “primes” the IBC cells’ cellular machinery to become extremely migratory in response to a chemoattractant. We determined that interleukins −6, −8, and −10 within the MCM are sufficient to stimulate this enhanced IBC migration effect, and that the known metastatic oncogene, RhoC GTPase, is necessary for the enhanced migration response.

Blocking Interleukin (IL)4- and IL13-Mediated Phosphorylation of STAT6 (Tyr641) Decreases M2 Polarization of Macrophages and Protects Against Macrophage-Mediated Radioresistance of Inflammatory Breast Cancer

“…Recently, elegant work by Shiao et al, using the orthotopic MMTV-PyMT mouse model of mammary carcinogenesis, showed that polarized TH2 macrophages and CD4þ T cells mediated tumor growth after radiation therapy, in part via suppression of CD8þ T cells (8). Further, Allen et al (9) recently reported that IL6, IL8, and IL10 from macrophage-derived conditioned medium enhanced migration of IBC cells. These findings suggest that macrophages have a role in the sensitivity of IBC cells to radiation, but this question has not yet been examined in great detail.…”

MicroRNA‐138 Inhibits Osteogenic Differentiation and Mineralization of Human Dedifferentiated Chondrocytes by Regulating RhoC and the Actin Cytoskeleton

“…We found that miR‐138 inhibits osteogenesis and matrix mineralization and noted that cell proliferation, cell shape, and cell migration were also affected. Analysis of potential miR‐138 target genes led us to pursue one specific target, RhoC, because this small‐molecular‐weight GTPase has been implicated in altering cell shape via regulation of the actin cytoskeleton, in addition to regulating processes controlling cell proliferation, migration, and invasion in other systems . Here, we have discovered a new mechanism in DDCs, whereby miR‐138 functions to suppress RhoC expression, which in turn inhibits F‐actin polymerization and the ability of these cells to proliferate, possibly migrate, and differentiate toward the osteogenic lineage.…”

Integration of high-content fluorescence imaging into the metabolic flux assay reveals insights into mitochondrial properties and functions

“…The Rho-like family of Rho-GTPases have been well characterized for their participation in the progression of breast cancer 32,34–36 and the alteration of metabolic phenotype 33 . Therefore, we next applied our imaging and analysis strategy to explore the potential for fragmented mitochondria in breast cancer cells that lack either the Rho-like family of Rho-GTPases RhoA or RhoC, via CRISPR/Cas9 knockout (WT, RhoA KO, RhoC KO) ( Supplementary Fig.…”