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Transarterial chemoembolization (TACE) is considered a standard local-regional treatment for intermediate-stage hepatocellular carcinoma (HCC) and the most common bridging therapy. This treatment is offered to more than 70% of patients who are on the waiting list for liver transplantation in the United States. HCC typically receives its blood supply from the hepatic artery; however, it can recruit a parasitic supply from extrahepatic collateral (EHC) arteries. The development of an EHC arterial blood supply can interfere with the therapeutic efficacy of TACE and result in treatment failure and poor outcome. Cross-sectional imaging-specifically computed tomography and magnetic resonance imaging-has some limitations in depicting the presence or absence of an EHC arterial supply during the pre-TACE evaluation. Catheterization and angiography of every possible EHC artery during a routine TACE procedure would be time consuming and technically challenging and would not always be feasible. Therefore, the prediction of a potential EHC arterial supply on the basis of tumor location before, during, and after TACE is fundamental to achieving optimal therapeutic efficacy. To perform TACE through EHC arteries, special considerations are necessary to avoid potentially serious complications. The authors review the factors influencing the development of an EHC arterial blood supply to HCC and describe a systematic approach to enhance the ability to predict the presence of EHC arteries. They also describe the proper technique for TACE of each EHC artery and how to avoid potential technique-related complications. RSNA, 2017.

Using differential cDNA library screening techniques based on metastatic and nonmetastatic rat mammary adenocarcinoma cell lines, we previously cloned and sequenced the metastasis-associated gene mta1. Using homology to the rat mta1 gene, we cloned the human MTA1 gene and found it to be over-expressed in a variety of human cell lines (breast, ovarian, lung, gastric and colorectal cancer but not melanoma or sarcoma) and cancerous tissues (breast, esophageal, colorectal, gastric and pancreatic cancer). We found a close similarity between the human MTA1 and rat mta1 genes (88% and 96% identities of the nucleotide and predicted amino acid sequences, respectively). Both genes encode novel proteins that contain a proline rich region (SH3-binding motif), a putative zinc finger motif, a leucine zipper motif and 5 copies of the SPXX motif found in gene regulatory proteins. Using Southern blot analysis the MTA1 gene was highly conserved, and using Northern blot analysis MTA1 transcripts were found in virtually all human cell lines (melanoma, breast, cervix and ovarian carcinoma cells and normal breast epithelial cells). However, the expression level of the MTA1 gene in normal breast epithelial cells was approximately 50% of that found in rapidly growing adenocarcinoma and atypical epithelial cell lines. Experimental inhibition of MTA1 protein expression using antisense phosphorothioate oligonucleotides resulted in inhibition of growth and invasion of human MDA-MB-231 breast cancer cells with relatively high MTA1 expression. Furthermore, the MTA1 protein was localized in the nuclei of cells transfected with a mammalian expression vector containing a full-length MTA1 gene. Although some MTA1 protein was found in the cytoplasm, the vast majority of MTA1 protein was localized in the nucleus. Examination of recombinate MTA1 and related MTA2 proteins suggests that MTA1 protein is a histone deacetylase. It also appears to behave like a GATA-element transcription factor, since transfection of a GATA-element reporter into MTA1-expressing cells resulted in 10-20-fold increase in reporter expression over poorly MTA1-expressing cells. Since it was reported that nucleosome remodeling histone deacetylase complex (NuRD complex) involved in chromatin remodeling contains MTA1 protein and a MTA1-related protein (MTA2), we examined NuRD complexes for the presence of MTA1 protein and found an association of this protein with histone deacetylase. The results suggest that the MTA1 protein may serve multiple functions in cellular signaling, chromosome remodeling and transcription processes that are important in the progression, invasion and growth of metastatic epithelial cells.