Effects of anti-miR-182 on TSP-1 expression in human colon cancer cells: there is a sense in antisense?
OBJECTIVE
miRNAs are attractive molecules for cancer treatment, including colon rectal cancer (CRC). We investigate on the molecular mechanism by which miR-182 could regulate thrombospondin-1 (TSP-1) expression, a protein downregulated in CRC and inversely correlated with tumor vascularity and metastasis.


BACKGROUND
MicroRNAs are small non-coding RNAs that regulate the expression of different genes, involved in cancer progression, angiogenesis and metastasis. miR-182, over-expressed in colorectal cancer (CRC), has like predictive target thrombospondin-1 (TSP-1), a protein inversely correlated with tumor vascularity and metastasis that results downregulated in different types of cancer including CRC.


RESULTS
We found that TSP-1 increased after transfection with anti-miR-182 and we showed that miR-182 targets TSP-1 3'UTR-mRNA in both cells. Moreover, we observed that anti-miR-182 did not induce significant variation of Egr-1 expression, but affected the nuclear translocation and its binding on tsp-1 promoter in HCT-116. Equally, Sp-1 was slightly increased as total protein, rather we found a nuclear accumulation and its loading on the TSP-1 promoter in HT-29 transfected with anti-miR-182.


CONCLUSIONS
Our data suggest that miR-182 targets the anti-angiogenic factor TSP-1 and that anti-miR-182 determines an upregulation of TSP-1 expression in colon cancer cells. Moreover, anti-miR-182 exerts a transcriptional regulatory mechanism of tsp-1 modulating Egr-1 and Sp-1 function. Anti-miR-182 could be used to restore TSP-1 expression in order to contrast angiogenic and invasive events in CRC.
Section of Medical Oncology, Department of Surgical, Oncological and Stomatological Sciences, University of Palermo , Via del Vespro 129, 90127, Palermo , Italy +011 39 091 6554529 ; lab-oncobiologia@usa.net.
Valeria
V
Amodeo
Viviana
V
Bazan
Daniele
D
Fanale
Lavinia
L
Insalaco
Stefano
S
Caruso
Giuseppe
G
Cicero
Giuseppe
G
Bronte
Christian
C
Rolfo
Daniele
D
Santini
Antonio
A
Russo
D001483:Base Sequence; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D060888:Real-Time Polymerase Chain Reaction; D019700:Thrombospondin 1 / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D035683:MicroRNAs; C538984:Mirn182 microRNA, human; D016376:Oligonucleotides, Antisense; D019700:Thrombospondin 1