PRL-3 engages the focal adhesion pathway in triple-negative breast cancer cells to alter actin structure and substrate adhesion properties critical for cell migration and invasion.

Triple-negative breast cancers (TNBCs) are among the most aggressive cancers characterized by a high propensity to invade, metastasize and relapse. We previously reported that the TNBC-specific inhibitor, AMPI-109, significantly impairs the ability of TNBC cells to migrate and invade by reducing levels of the metastasis-promoting phosphatase, PRL-3. Here, we examined the mechanisms by which AMPI-109 and loss of PRL-3 impede cell migration and invasion. AMPI-109 treatment or knock down of PRL-3 expression were associated with deactivation of Src and ERK signaling and concomitant downregulation of RhoA and Rac1/2/3 GTPase protein levels. These cellular changes led to rearranged filamentous actin networks necessary for cell migration and invasion. Conversely, overexpression of PRL-3 promoted TNBC cell invasion by upregulating matrix metalloproteinase 10, which resulted in increased TNBC cell adherence to, and degradation of, the major basement membrane component laminin. Our data demonstrate that PRL-3 engages the focal adhesion pathway in TNBC cells as a key mechanism for promoting TNBC cell migration and invasion. Collectively, these data suggest that blocking PRL-3 activity may be an effective method for reducing the metastatic potential of TNBC cells.

Gari HH ，DeGala GD ，Ray R ，Lucia MS ，Lambert JR ... -  《-》

Genome-wide functional genetic screen with the anticancer agent AMPI-109 identifies PRL-3 as an oncogenic driver in triple-negative breast cancers.

Gari HH ，Gearheart CM ，Fosmire S ，DeGala GD ，Fan Z ，Torkko KC ，Edgerton SM ，Lucia MS ，Ray R ，Thor AD ，Porter CC ，Lambert JR ... -  《-》

Diaphanous-related formin-3 overexpression inhibits the migration and invasion of triple-negative breast cancer by inhibiting RhoA-GTP expression.

Triple-negative breast cancer (TNBC) is associated with a high risk of metastasis, recurrence, and poor prognosis. TNBC is insensitive to existing endocrine and targeted breast cancer therapies because it lacks the expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Therefore, there is an urgent need for identifying novel targets to improve the efficacy of TNBC treatment. Diaphanous-related formin-3 (DIAPH3) regulates cytoskeleton formation to regulate cell adhesion, migration, and differentiation. A previous study showed that DIAPH3 promoted the metastasis of prostate cancer. However, DIAPH3 expression in TNBC and its effect on TNBC development have not been reported to date. In present study, we investigated the expression and functions of DIAPH3 in TNBC. Results of immunohistochemical staining showed that DIAPH3 expression significantly decreased in breast cancer tissues, especially TNBC tissues, compared with that in paired non-tumor tissues. In addition, DIAPH3 expression was associated with TNM stage and lymph node metastasis, but not with tumor size in patients with TNBC. Further, DIAPH3 overexpression clearly suppressed the migration and invasion of MDA-MB-231 cells and decreased the expression of Ras Homolog Family Member A (RhoA), RhoA-GTP, Matrix Metallopeptidase 2 (MMP-2), and MMP-9. Thus, we predict that DIAPH3 overexpression inhibits the migration and invasion of TNBC by inhibiting RhoA-GTP expression and the results of the present study provide new insights for developing DIAPH3-targeting therapies for TNBC.

Jiang J 《-》

Phosphatase of regenerating liver-3 promotes migration and invasion by upregulating matrix metalloproteinases-7 in human colorectal cancer cells.

Phosphatase of regenerating liver (PRL)-3, a member of a subgroup of protein tyrosine phosphatases that can stimulate the degradation of the extracellular matrix, is over-expressed in metastatic colorectal cancer (CRC) relative to primary tumors. To determine whether PRL-3-induced enhancement of migration and invasion is dependent on the expression of matrix metalloproteinases (MMPs), PRL-3 was expressed in DLD-1 human CRC cells. The motility, migration and invasion characteristics of the cells were examined, and metastasis to the lung was confirmed in a nude mouse using PRL-3-overexpressing DLD-1 cells [DLD-1 (PRL-3)]. Migration and invasion of the cells were inhibited by phosphatase and farnesyltransferase inhibitors. Expression of MMPs was enhanced 3- to 10-fold in comparison to control cells, and migration and invasion were partially inhibited by small interfering RNA (siRNA) knockdown of MMP-2, -13 or -14. Importantly, siRNA knockdown of MMP-7 completely inhibited the migration and invasion of DLD-1 (PRL-3) cells, whereas overexpression of MMP-7 increased migration. The expression of MMP-7 was also downregulated by phosphatase and farnesyltransferase inhibitors. It was found that PRL-3 induced MMP-7 through oncogenic pathways including PI3K/AKT and ERK and that there is a relationship between the expression of PRL-3 and MMP-7 in human tumor cell lines. The expression of MMP-13 and -14 was very sensitive to the inhibition of farnesyltransferase; however, the migration and invasion of DLD-1 (PRL-3) cells did not strongly depend on the expression of MMP-13 or -14. These results suggest that the migration and invasion of PRL-3-expressing CRC cells depends primarily on the expression of MMP-7.

Lee SK ，Han YM ，Yun J ，Lee CW ，Shin DS ，Ha YR ，Kim J ，Koh JS ，Hong SH ，Han DC ，Kwon BM ... -  《-》

3,4-Methylenedioxy-β-nitrostyrene inhibits adhesion and migration of human triple-negative breast cancer cells by suppressing β1 integrin function and surface protein disulfide isomerase.

Triple negative breast cancer (TNBC) exhibits an aggressive clinical course by high metastatic potential. It is known that integrin-mediated cell adhesion and migration are important for cancer metastasis. In the present study, a synthetic compound, 3, 4-methyenedioxy-β-nitrostyrene (MNS), significantly inhibited adhesion of TNBC cell lines to different extracellular matrix (ECM) components. The antimetastatic capacity of MNS was also observed through reducing TNBC cells migration and invasion without affecting cell viability. Confocal microscopy revealed that MNS disrupted the formation of focal adhesion complex and actin stress fiber networks. Consistent with this finding, MNS inhibited phosphorylation of focal adhesion kinase (FAK) and paxillin as detected by Western blot analysis. In exploring the underlying mechanism, we found that MNS inhibited phosphorylation of FAK as a result of reducing β1 integrin activation and clustering. A cell-impermeable dithiol reagent, 2, 3-dimercaptopropane-1-sulfonic acid abrogated all of MNS's actions, indicating that MNS may react with thiol groups of cell surface proteins that are involved in regulation of β1 integrin function as well as cell adhesion and migration. Cell surface protein disulfide isomerase (PDI) has been reported to be essential for the affinity modulation of β integrins. We also demonstrated that MNS inhibited PDI activity both in a pure enzyme system and in intact cancer cells. Taken together, our results suggest that MNS inhibits in vitro metastatic properties of TNBC cells through suppression of β1 integrin activation and focal adhesion signaling. Moreover, inhibition of surface PDI may contribute, at least in part, to the actions of MNS. These results suggest that MNS has a potential to be developed as an anticancer agent for treatment of TNBC.

Chen IH ，Chang FR ，Wu YC ，Kung PH ，Wu CC ... -  《-》