Polo-like Kinase I is involved in Invasion through Extracellular Matrix

Polo-like kinase 1, PLK1, has important functions in maintaining genome stability and is involved in regulation of mitosis. PLK1 is up regulated in many invasive carcinomas. We asked whether it may also play a role in acquisition of invasiveness, a crucial step in transition to malignancy. In a model of metaplastic basal-like breast carcinoma progression, we found that PLK1 expression is necessary but not sufficient to induce invasiveness through laminin-rich extracellular matrix. PLK1 mediates invasion via Vimentin and {beta}1 integrin, both of which are necessary. We observed that PLK1 phosphorylates Vimentin on serine 82, which in turn regulates cell surface levels of {beta}1 integrin. We found PLK1 to be also highly expressed in pre-invasive in situ carcinomas of the breast. These results support a role for the involvement of PLK1 in the invasion process and point to this pathway as a potential therapeutic target for pre-invasive and invasive breast carcinoma treatment

Site-specific inductive and inhibitory activities of MMP-2 and MMP-3 orchestrate mammary gland branching morphogenesis

During puberty, mouse mammary epithelial ducts invade the stromal mammary fat pad in a wave of branching morphogenesis to form a complex ductal tree. Using pharmacologic and genetic approaches, we find that mammary gland branching morphogenesis requires transient matrix metalloproteinase (MMP) activity for invasion and branch point selection. MMP-2, but not MMP-9, facilitates terminal end bud invasion by inhibiting epithelial cell apoptosis at the start of puberty. Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty. In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy. Nevertheless, the mammary gland is able to develop lactational competence in MMP mutant mice. Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis

RECK is not an independent prognostic marker for breast cancer

Abstract\ud \ud Background\ud The REversion-inducing Cysteine-rich protein with Kazal motif (RECK) is a well-known inhibitor of matrix metalloproteinases (MMPs) and cellular invasion. Although high expression levels of RECK have already been correlated with a better clinical outcome for several tumor types, its main function, as well as its potential prognostic value for breast cancer patients, remain unclear.\ud \ud \ud Methods\ud The RECK expression profile was investigated in a panel of human breast cell lines with distinct aggressiveness potential. RECK functional analysis was undertaken using RNA interference methodology. RECK protein levels were also analyzed in 1040 cases of breast cancer using immunohistochemistry and tissue microarrays (TMAs). The association between RECK expression and different clinico-pathological parameters, as well as the overall (OS) and disease-free (DFS) survival rates, were evaluated.\ud \ud \ud Results\ud Higher RECK protein expression levels were detected in more aggressive breast cancer cell lines (T4-2, MDA-MB-231 and Hs578T) than in non-invasive (MCF-7 and T47D) and non-tumorigenic (S1) cell lines. Indeed, silencing RECK in MDA-MB-231 cells resulted in elevated levels of pro-MMP-9 and increased invasion compared with scrambled (control) cells, without any effect on cell proliferation. Surprisingly, by RECK immunoreactivity analysis on TMAs, we found no association between RECK positivity and survival (OS and DFS) in breast cancer patients. Even considering the different tumor subtypes (luminal A, luminal B, Her2 type and basal-like) or lymph node status, RECK remained ineffective for predicting the disease outcome. Moreover, by multivariate Cox regression analysis, we found that RECK has no prognostic impact for OS and DFS, relative to standard clinical variables.\ud \ud \ud Conclusions\ud Although it continues to serve as an invasion and MMP inhibitor in breast cancer, RECK expression analysis is not useful for prognosis of these patients.Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Pesquisa (CNPq)Financiadora de Estudos e Projetos (FINEP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Banco Nacional de Desenvolvimento Social e Econômico (BNDES – FUNTEC)Departamento de Ciência e Tecnologia em Saúde - Ministério da Saúde (DECIT-MS) and Ministério da Ciência, Tecnologia e Inovação (MCTI)

A human breast cell model of pre-invasive to invasive transition

A crucial step in human breast cancer progression is the acquisition of invasiveness. There is a distinct lack of human cell culture models to study the transition from pre-invasive to invasive phenotype as it may occur 'spontaneously' in vivo. To delineate molecular alterations important for this transition, we isolated human breast epithelial cell lines that showed partial loss of tissue polarity in three-dimensional reconstituted-basement membrane cultures. These cells remained non-invasive; however, unlike their non-malignant counterparts, they exhibited a high propensity to acquire invasiveness through basement membrane in culture. The genomic aberrations and gene expression profiles of the cells in this model showed a high degree of similarity to primary breast tumor profiles. The xenograft tumors formed by the cell lines in three different microenvironments in nude mice displayed metaplastic phenotypes, including squamous and basal characteristics, with invasive cells exhibiting features of higher grade tumors. To find functionally significant changes in transition from pre-invasive to invasive phenotype, we performed attribute profile clustering analysis on the list of genes differentially expressed between pre-invasive and invasive cells. We found integral membrane proteins, transcription factors, kinases, transport molecules, and chemokines to be highly represented. In addition, expression of matrix metalloproteinases MMP-9,-13,-15,-17 was up regulated in the invasive cells. Using siRNA based approaches, we found these MMPs to be required for the invasive phenotype. This model provides a new tool for dissection of mechanisms by which pre-invasive breast cells could acquire invasiveness in a metaplastic context

Mammary gland development: cell fate specification, stem cells and the microenvironment

The development of the mammary gland is unique: the final stages of development occur postnatally at puberty under the influence of hormonal cues. Furthermore, during the life of the female, the mammary gland can undergo many rounds of expansion and proliferation. The mammary gland thus provides an excellent model for studying the ‘stem/progenitor’ cells that allow this repeated expansion and renewal. In this Review, we provide an overview of the different cell types that constitute the mammary gland, and discuss how these cell types arise and differentiate. As cellular differentiation cannot occur without proper signals, we also describe how the tissue microenvironment influences mammary gland development.</jats:p

[10]-Gingerol Reverts Malignant Phenotype of Breast Cancer Cells in 3D Culture.

Breast cancer is a complex and multifactorial disease. Tumors have a heterogeneous microenvironment, which have multiple interactions with other cell types, greatly influencing the behavior of tumor cells and response to therapy. The 3D culture mimics the microenvironment better found in vivo and is more appropriated than the traditional 2D culture made from plastic to test the cellular response to drugs. To investigate the effects of [10]-gingerol on breast tumor cells, we used physiologically relevant three-dimensional (3D) cultures of malignant and non-malignant human breast cells grown in laminin-rich extracellular matrix gels (lr-ECM). Our results showed selective cytotoxicity of [10]-gingerol against the malignant T4-2 breast cancer cell line compared to non-malignant S1 cells. The compound reverted the malignant phenotype of the cancer cells, downregulating the expression of epidermal growth factor receptor (EGFR) and β1-integrin. Moreover, [10]-gingerol induced apoptosis in this cell line. These results suggest that [10]-gingerol may be an effective compound to use as adjuvant therapy in breast cancer treatment. J. Cell. Biochem. 118: 2693-2699, 2017. © 2017 Wiley Periodicals, Inc