title: RKIP Inhibits Local Breast Cancer Invasion by Antagonizing the Transcriptional Activation of MMP13.
abstract: Raf Kinase Inhibitory Protein or RKIP was initially identified as a Raf-1 binding protein using the yeast 2-hybrid screen. RKIP inhibits the activation phosphorylation of MEK by Raf-1 by competitively inhibiting the binding of MEK to Raf-1 and thus exerting an inhibitory effect on the Raf-MEK-Erk pathway. RKIP has been identified as a metastasis suppressor gene. Expression of RKIP is low in cancer metastases. Although primary tumor growth remains unaffected, re- expression of RKIP inhibits cancer metastasis. Mechanistically, RKIP constrains metastasis by inhibiting angiogenesis, local invasion, intravasation, and colonization. The molecular mechanism of how RKIP inhibits these individual steps remains undefined. In our present study, using an unbiased PCR based screening and by analyzing DNA microarray expression datasets we observe that the expression of multiple metalloproteases (MMPs) including MMP1, MMP3, MMP10 and MMP13 are negatively correlated with RKIP expression in breast cancer cell lines and clinical samples. Since expression of MMPs by cancer cells is important for cancer metastasis, we hypothesize that RKIP may mediate suppression of breast cancer metastasis by inhibiting multiple MMPs. We show that the expression signature of RKIP and MMPs is better at predicting high metastatic risk than the individual gene. Using a combination of loss- and gain-of-function approaches, we find that MMP13 is the cause of RKIP-mediated inhibition of local cancer invasion. Interestingly expression of MMP13 alone is not sufficient to reverse the inhibition of breast cancer cell metastasis to the lung due to the expression of RKIP. We find that RKIP negatively regulates MMP13 through the Erk2 signaling pathway and the repression of MMP13 by RKIP is transcription factor AP-1 independent. Together, our findings indicate that RKIP inhibits cancer cell invasion, in part, via MMP13 inhibition. These data also implicate RKIP in the regulation of MMP transcription, suggesting a potential mechanism by which RKIP inhibits tumor progression and metastasis.
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Ila
authors: I
authors: Datar
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Jingwei
authors: J
authors: Feng
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Xiaoliang
authors: X
authors: Qiu
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: John
authors: J
authors: Lewandowski
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Miranda
authors: M
authors: Yeung
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Gang
authors: G
authors: Ren
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Shweta
authors: S
authors: Aras
authors: Kuwait University, Faculty of Medicine, P.O. Box 24923, Safat, Kuwait.
authors: Fahd
authors: F
authors: Al-Mulla
authors: State Key Laboratory Of Silkworm Genome Biology, Chongqing, China.
authors: Hongjuan
authors: H
authors: Cui
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Robert
authors: R
authors: Trumbly
authors: Department of Pathology, University of Toledo, College of Medicine, Health Science Campus, Toledo Ohio, United States of America.
authors: Sri Krishna Chaitanya
authors: SK
authors: Arudra
authors: Department of Pathology, University of Toledo, College of Medicine, Health Science Campus, Toledo Ohio, United States of America.
authors: Luis E
authors: LE
authors: De Las Casas
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Ivana
authors: I
authors: de la Serna
authors: Kuwait University, Faculty of Medicine, P.O. Box 24923, Safat, Kuwait.
authors: Milad S
authors: MS
authors: Bitar
authors: Department of Biochemistry and Cancer Biology, University of Toledo, College of Medicine, Health Science Campus, Toledo, Ohio, United States of America.
authors: Kam C
authors: KC
authors: Yeung
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D018572:Disease-Free Survival; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053509:Matrix Metalloproteinase 13 / Q000235:genetics*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D049488:Phosphatidylethanolamine Binding Protein / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation
chemical_list: D049488:Phosphatidylethanolamine Binding Protein; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D053509:Matrix Metalloproteinase 13