LOXL2-Mediated Matrix Remodeling in Metastasis and Mammary Gland Involution

Barker, Holly E.; Chang, Joan; Cox, Thomas R.; Lang, Georgina; Bird, Dennis K.; Nicolau, Monica; Evans, Holly; Gartland, Alison; Erler, Janine T.

doi:10.1158/0008-5472.can-10-2868

Cited by 230 publications

(266 citation statements)

References 43 publications

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“…We have previously shown that inhibiting LOXL2 in mammary cancer cells reduces tumor cell invasion and metastasis without reducing primary tumor growth (24). The data we have presented here suggest that the decreased metastasis observed following LOXL2 inhibition is due not only to decreased invasion of the tumor cells themselves but also to reduced fibroblast activation in the tumor stroma.…”

Section: Discussionsupporting

confidence: 50%

“…4T1 cells were infected with a scrambled control or mouse LOXL2-specific shRNA viruses to generate knockdown (4T1 shLOXL2) and control (4T1 control) cell lines. The shLOXL2 cell lines had significantly decreased expression of LOXL2 mRNA and protein compared with controls (24). ELISA and activity assays were conducted to further confirm that shLOXL2 cells expressed less LOXL2 protein and had lower LOXL2 activity (Supplementary Fig.…”

Section: Inhibition Of Loxl2 Reduces A-sma Expression In 4t1 Orthotopmentioning

confidence: 97%

“…We have previously shown that blocking mammary tumor cell-derived lysyl oxidase-like 2 (LOXL2) significantly inhibits mammary tumor cell invasion and metastasis in transgenic and orthotopic mouse models (24). In this study, we investigate the role of LOXL2 in the tumor stroma and show that LOXL2 mediates fibroblast activation through integrin engagement and FAK signaling.…”

Section: Introductionmentioning

confidence: 93%

“…We have previously shown that LOXL2 expression is clinically correlated with metastasis and that 4T1 mouse mammary cancer cells metastasize in a LOXL2-dependent manner in vivo (24). We sought to better understand how tumor-derived LOXL2 could enhance tumor progression, with a focus on fibroblast activation.…”

Section: Inhibition Of Loxl2 Reduces A-sma Expression In 4t1 Orthotopmentioning

confidence: 99%

“…4T1 wild-type (4T1 wt) cells were also implanted into Balb/c mice and these mice received twice weekly doses of either a control IgG or a LOXL2-specific targeting antibody (24), to block secreted LOXL2 function. Tumors were harvested when they reached maximum size.…”

Section: Inhibition Of Loxl2 Reduces A-sma Expression In 4t1 Orthotopmentioning

confidence: 99%

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Tumor-Secreted LOXL2 Activates Fibroblasts through FAK Signaling

Barker

Bird

Lang

et al. 2013

Molecular Cancer Research

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Cancer-associated fibroblasts enhance cancer progression when activated by tumor cells through mechanisms not yet fully understood. Blocking mammary tumor cell-derived lysyl oxidase-like 2 (LOXL2) significantly inhibited mammary tumor cell invasion and metastasis in transgenic and orthotopic mouse models. Here, we discovered that tumor-derived LOXL2 directly activated stromal fibroblasts in the tumor microenvironment. Genetic manipulation or antibody inhibition of LOXL2 in orthotopically grown mammary tumors reduced the expression of a-smooth muscle actin (a-SMA). Using a marker for reticular fibroblasts, it was determined that expression of a-SMA was localized to fibroblasts recruited from the host tissue. This marker also revealed that the matrix present in tumors with reduced levels of LOXL2 was more scattered compared with control tumors which exhibited matrices with dense, parallel alignments. Importantly, in vitro assays revealed that tumor-derived LOXL2 and a recombinant LOXL2 protein induced fibroblast branching on collagen matrices, as well as increased fibroblast-mediated collagen contraction and invasion of fibroblasts through extracellular matrix. Moreover, LOXL2 induced the expression of a-SMA in fibroblasts grown on collagen matrices. Mechanistically, it was determined that LOXL2 activated fibroblasts through integrinmediated focal adhesion kinase activation. These results indicate that inhibition of LOXL2 in tumors not only reduces tumor cell invasion but also attenuates the activation of host cells in the tumor microenvironment.Implications: These findings reveal new insight into the mechanisms of fibroblast activation, a novel function of LOXL2, and further highlight the importance of generating LOXL2-targeted therapies for the prevention of tumor progression and metastasis.

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Section: Discussionsupporting

confidence: 50%

Section: Inhibition Of Loxl2 Reduces A-sma Expression In 4t1 Orthotopmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 93%

Section: Inhibition Of Loxl2 Reduces A-sma Expression In 4t1 Orthotopmentioning

confidence: 99%

Section: Inhibition Of Loxl2 Reduces A-sma Expression In 4t1 Orthotopmentioning

confidence: 99%

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Tumor-Secreted LOXL2 Activates Fibroblasts through FAK Signaling

Barker

Bird

Lang

et al. 2013

Molecular Cancer Research

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Lysyl Oxidase Like‐2 (LOXL2): An Emerging Oncology Target

Chopra

Sangarappillai

Romero‐Canelón

et al. 2020

Advanced Therapeutics

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Lysyl oxidase‐like 2 (LOXL2) is an emerging drug target against metastatic disease owing to its role in the upregulation of key processes including epithelial‐mesenchymal transition (EMT) and invasion. Recent activity in the field of small molecule LOXL2 inhibitor development by pharmaceutical and academic laboratories has renewed interest in targeting LOXL2. Herein, 1) the viability of LOXL2 as a drug target for the treatment of metastatic disease through an investigation of its biological actions is determined; 2) the pitfalls of an antibody approach are considered; and 3) the small molecule approaches emerging in the scientific and patent literature are reviewed. This review identifies that LOXL2 is localized and active intracellularly and extracellularly in invasive cancer cells. LOXL2 has been implicated in a number of established signaling pathways involved in tumor progression, further highlighting its appeal as a target in metastatic disease. Previously, limited chemical inhibitors have been developed; however, their selectivity profile for the LOX family has proven controversial. Antibodies, such as simtuzumab, have been developed selectively against LOXL2. Simtuzumab, in particular, progresses into phase II trials but it was ultimately terminated. The small molecule inhibitors of LOXL2 are summarized, some of which are now in the early stages of clinical trials.

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Establishment of a 3D co‐culture model to investigate the role of primary fibroblasts in ductal carcinoma in situ of the breast

et al. 2022

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Background Ductal carcinoma in situ (DCIS) is a precursor form of breast cancer. 13%–50% of these lesions will progress to invasive breast cancer, but the individual progression risk cannot be estimated. Therefore, all patients receive the same therapy, resulting in potential overtreatment of a large proportion of patients. Aims The role of the tumor microenvironment (TME) and especially of fibroblasts appears to be critical in DCIS development and a better understanding of their role may aid individualized treatment. Methods and results Primary fibroblasts isolated from benign or malignant punch biopsies of the breast and MCF10DCIS.com cells were seeded in a 3D cell culture system. The fibroblasts were cultured in a type I collagen layer beneath a Matrigel layer with MCF10DCIS.com cells. Dye‐quenched (DQ) fluorescent collagen I and IV were used in collagen and Matrigel layer respectively to demonstrate proteolysis. Confocal microscopy was performed on day 2, 7, and 14 to reveal morphological changes, which could indicate the transition to an invasive phenotype. MCF10DCIS.com cells form smooth, round spheroids in co‐culture with non‐cancer associated fibroblasts (NAFs). Spheroids in co‐culture with tumor‐associated fibroblasts (TAFs) appear irregularly shaped and with an uneven surface; similar to spheroids formed from invasive cells. Therefore, these morphological changes represent the progression of an in situ to an invasive phenotype. In addition, TAFs show a higher proteolytic activity compared to NAFs. The distance between DCIS cells and fibroblasts decreases over time. Conclusion The TAFs seem to play an important role in the progression of DCIS to invasive breast cancer. The better characterization of the TME could lead to the identification of DCIS lesions with high or low risk of progression. This could enable personalized oncological therapy, prevention of overtreatment and individualized hormone replacement therapy after DCIS.

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LOXL2-Mediated Matrix Remodeling in Metastasis and Mammary Gland Involution

Cited by 230 publications

References 43 publications

Tumor-Secreted LOXL2 Activates Fibroblasts through FAK Signaling

Tumor-Secreted LOXL2 Activates Fibroblasts through FAK Signaling

Lysyl Oxidase Like‐2 (LOXL2): An Emerging Oncology Target

Establishment of a 3D co‐culture model to investigate the role of primary fibroblasts in ductal carcinoma in situ of the breast

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