Mutations in BALB mitochondrial DNA induce CCL20 up-regulation promoting tumorigenic phenotypes

Silencing of MicroRNA-503 in Rat Mesenchymal Stem Cells Exerts Potent Antitumorigenic Effects in Lung Cancer Cells

Purpose

Mesenchymal stem cells (MSCs) are largely studied for their potential clinical use. Recently, there has been gained further interest in the relationship between MSCs and tumorigenesis. MSCs are reported to both promote and abrogate tumor growth. The present study was designed to investigate whether miRNAs are involved in the interactions between MSCs and tumor cells in the tumor microenvironment.

Materials and Methods

Rat bone marrow-derived MSCs (rMSCs) were cultured with or without tumor-conditioned medium (TCM) to observe the effect upon MSCs by TCM. Microarrays and real-time PCR were performed between the two groups. A series of experiments were used to reveal the functional significance of microRNA-503 (miR-503) in rMSCs. Furthermore, the antitumorigenic effect of silencing of miR-503 in rMSCs (miR-503-i-rMSCs) in vivo was measured.

Results

We found that rMSCs in vitro exhibited tumor-promoting properties in TCM, and the microRNA profiles of rMSCs were significantly altered in TCM. However, miR-503-i-rMSCs can decrease the angiogenesis and growth of A549 cells. We also demonstrated in an in vivo tumor model that miR-503-i-rMSCs inhibited A549 tumor angiogenesis and significantly abrogated tumor initiation and growth. CD133 assays in peripheral blood and A549 xenografts further validated that miR-503-i-rMSCs, rather than rMSCs, exerted an antitumorigenic action in the A549 tumor model.

Conclusion

Our results suggest that miR-503-i-rMSCs are capable of tumor suppression. Further studies are required to develop clinical therapies based on the inhibition of the tumor-promoting properties and potentiation of the anti-tumor properties of MSCs.

Genetic Target Modulation Employing CRISPR/Cas9 Identifies Glyoxalase 1 as a Novel Molecular Determinant of Invasion and Metastasis in A375 Human Malignant Melanoma Cells In Vitro and In Vivo

Metabolic reprogramming is a molecular hallmark of cancer. Recently, we have reported the overexpression of glyoxalase 1 (encoded by GLO1), a glutathione-dependent enzyme involved in detoxification of the reactive glycolytic byproduct methylglyoxal, in human malignant melanoma cell culture models and clinical samples. However, the specific role of GLO1 in melanomagenesis remains largely unexplored. Here, using genetic target modulation, we report the identification of GLO1 as a novel molecular determinant of invasion and metastasis in malignant melanoma. First, A375 human malignant melanoma cells with GLO1 deletion (A375-GLO1_KO) were engineered using CRISPR/Cas9, and genetic rescue clones were generated by stable transfection of KO clones employing a CMV-driven GLO1 construct (A375-GLO1_R). After confirming GLO1 target modulation at the mRNA and protein levels (RT-qPCR, immunodetection, enzymatic activity), phenotypic characterization indicated that deletion of GLO1 does not impact proliferative capacity while causing significant sensitization to methylglyoxal-, chemotherapy-, and starvation-induced cytotoxic stress. Employing differential gene expression array analysis (A375-GLO1_KO versus A375-GLO1_WT), pronounced modulation of epithelial--mesenchymal transition (EMT)-related genes [upregulated: CDH1, OCLN, IL1RN, PDGFRB, SNAI3; (downregulated): BMP1, CDH2, CTNNB1, FN1, FTH1, FZD7, MELTF, MMP2, MMP9, MYC, PTGS2, SNAI2, TFRC, TWIST1, VIM, WNT5A, ZEB1, and ZEB2 (up to tenfold; p < 0.05)] was observed-all of which are consistent with EMT suppression as a result of GLO1 deletion. Importantly, these expression changes were largely reversed upon genetic rescue employing A375-GLO1_R cells. Differential expression of MMP9 as a function of GLO1 status was further substantiated by enzymatic activity and ELISA analysis; phenotypic assessment revealed the pronounced attenuation of morphological potential, transwell migration, and matrigel 3D-invasion capacity displayed by A375-GLO1_KO cells, reversed again in genetic rescue clones. Strikingly, in a SCID mouse metastasis model, lung tumor burden imposed by A375-GLO1_KO cells was strongly attenuated as compared to A375-GLO1_WT cells. Taken together, these prototype data provide evidence in support of a novel function of GLO1 in melanoma cell invasiveness and metastasis, and ongoing investigations explore the function and therapeutic potential of GLO1 as a novel melanoma target.