Germline gain-of-function MMP11 variant results in an aggressive form of colorectal cancer

Matrix metalloproteinase-11 (MMP11) is an enzyme with proteolytic activity against matrix and nonmatrix proteins. Although most MMPs are secreted as inactive proenzymes and are later activated extracellularly, MMP11 is activated intracellularly by furin within the constitutive secretory pathway. It is a key factor in physiological tissue remodeling and its alteration may play an important role in the progression of epithelial malignancies and other diseases. TCGA colon and colorectal adenocarcinoma data showed that upregulation of MMP11 expression correlates with tumorigenesis and malignancy. Here, we provide evidence that a germline variant in the MMP11 gene (NM_005940: c.232C>T; p.(Pro78Ser)), identified by whole exome sequencing, can increase the tumorigenic properties of colorectal cancer (CRC) cells. P78S is located in the prodomain region, which is responsible for blocking MMP11's protease activity. This variant was detected in the proband and all the cancer-affected family members analyzed, while it was not detected in healthy relatives. In silico analyses predict that P78S could have an impact on the activation of the enzyme. Furthermore, our in vitro analyses show that the expression of P78S in HCT116 cells increases tumor cell invasion and proliferation. In summary, our results show that this variant could modify the structure of the MMP11 prodomain, producing a premature or uncontrolled activation of the enzyme that may contribute to an early CRC onset in these patients. The study of this gene in other CRC cases will provide further information about its role in CRC development, which might improve patient treatment in the future.

MMP11 promotes the proliferation and progression of breast cancer through stabilizing Smad2 protein

Breast cancer (BC) is one of the most common malignant tumours in women. The matrix metalloproteinase (MMP) enzyme family plays a complex role in the development of BC. There is increasing evidence that MMP11 plays a major role in BC; however, the underlying mechanisms are not clear. The present study confirmed by analysing clinical samples and TCGA data sets, that high expression of MMP11 in clinical samples of BC was strongly associated with a poor prognosis in BC patients. In addition, MTT and colony formation assays indicated that the proliferative capacity of BC was affected when MMP11 expression changed. Furthermore, pathway enrichment analysis was performed and it was revealed that the TGF‑β signalling pathway was a potential downstream target of MMP11. In the TGF‑β signalling pathway, MMP11 could significantly regulate the protein expression levels of Smad2 and Smad3 and inhibit the degradation of Smad2 through the ubiquitin proteasome pathway as determined by western blotting. In vivo, it was further verified that MMP11 knockdown could inhibit tumour proliferation and growth. Collectively, the present results demonstrated that MMP11 inhibited the degradation of Smad2 in the TGF‑β signalling pathway, thereby promoting the development of BC. Thus, MMP11 expression was not only revealed to be an important indicator of BC prognosis but may also be an important therapeutic target for further prevention of BC growth and proliferation. The present study indicated that MMP11‑targeted therapy may provide new solutions for BC treatment.