The RhoA pathway mediates MMP‐2 and MMP‐9‐independent invasive behavior in a triple‐negative breast cancer cell line

Abstract

Breast cancer is a heterogeneous disease that varies in its biology and response to therapy. A foremost threat to patients is tumor invasion and metastasis, with the greatest risk among patients diagnosed with triple-negative and/or basal-like breast cancers. A greater understanding of the molecular mechanisms underlying cancer cell spreading is needed as 90% of cancer-associated deaths result from metastasis. We previously demonstrated that the Tamoxifen-selected, MCF-7 derivative, TMX2-28, lacks expression of estrogen receptor α (ERα) and is highly invasive, yet maintains an epithelial morphology. The present study was designed to further characterize TMX2-28 cells and elucidate their invasion mechanism. We found that TMX2-28 cells do not express human epidermal growth factor receptor 2 (HER2) and progesterone receptor (PR), in addition to lacking ERα, making the cells triple-negative. We then determined that TMX2-28 cells lack expression of active matrix metalloproteinases (MMPs)-1, MMP-2, MMP-9, and other genes involved in epithelial-mesenchymal transition (EMT) suggesting that TMX2-28 may not utilize mesenchymal invasion. In contrast, TMX2-28 cells have high expression of Ras Homolog Gene Family Member, A (RhoA), a protein known to play a critical role in amoeboid invasion. Blocking RhoA activity with the RhoA pathway specific inhibitor H-1152, or a RhoA specific siRNA, resulted in inhibition of invasive behavior. Collectively, these results suggest that TMX2-28 breast cancer cells exploit a RhoA-dependent, proteolytic-independent invasion mechanism. Targeting the RhoA pathway in triple-negative, basal-like breast cancers that have a proteolytic-independent invasion mechanism may provide therapeutic strategies for the treatment of patients with increased risk of metastasis.

Suppressive Effects of Plumbagin on Invasion and Migration of Breast Cancer Cells via the Inhibition of STAT3 Signaling and Down-regulation of Inflammatory Cytokine Expressions

“…MDA-MB-231SArfp cells treated with plumbagin for 24 h, mRNA expression levels of MMP-2 and MMP-9 in the matrix metalloproteinases family was decreased. Positive expression of MMP-2 and MMP-9 in tumor cells plays a vital role in their migration and invasion in vivo (26). MMP-9 is especially noted for decomposing the collagenous component of the ECM and devastating basic construction of collagen networks, thereby facilitating local invasion and distant migration (27).…”

LncRNA PCGEM1 Induces Ovarian Carcinoma Tumorigenesis and Progression Through RhoA Pathway

“…YAP is the major downstream cascade of Hippo signaling, designated the Hippo-YAP pathway, and has been identified as a candidate oncogene [15][16][17][18][19], Zhang et al showed that RhoA knockdown mediated YAP downregulation, promoting apoptosis and inhibiting cell proliferation, cell cycle progression, and migration [20]. As reviewed by Hall [21], RhoA exerts multiple functions in tumor metastasis by orchestrating the action of multiple downstream effectors and promoting extracellular matrix degradation and reconstruction; Fagan-Solis et al showed that blocking RhoA activity inhibited the invasive behavior of breast cancer cells by inhibiting MMP2 and MMP9 directly [22]. We found that RHOA gene silencing decreased the protein expression of RhoA and its downstream targets YAP, P70S6K, MMP2, and Bcl-xL.…”

The role of RhoA in vulvar squamous cell carcinoma: a carcinogenesis, progression, and target therapy marker

“…For example, RhoA depletion diminishes motility, invasion [13,14], and proliferation [15] and increases apoptosis [16,17]. It has been reported that RhoA expression is an independent prognostic factor in gastric cancer, especially diffuse-type gastric cancer [18].…”