Multivariate analysis of prognostic factors for survival following doxorubicin-eluting bead transarterial chemoembolization for hepatocellular carcinoma.

PURPOSE: To identify prognostic factors for survival in patients with hepatocellular carcinoma (HCC) treated with transarterial chemoembolization with doxorubicin-eluting beads (DEBs). MATERIALS AND METHODS: In a retrospective, single-center analysis, tumor- and patient-related factors were recorded for univariate and multivariate analyses via Kaplan-Meier and Cox regression. Infiltrative HCC phenotype and portal vein invasion (PVI) were correlated, and patients with either or both were classified as having radiographically advanced (RAdv) HCC. The primary endpoint was overall survival, which was calculated from the time of first DEB chemoembolization procedure. RESULTS: A total of 168 patients underwent 248 procedures, of which 215 (86.7%) were outpatient procedures. Mean length of stay was 0.33 days, and 25 patients (10.1%) were readmitted within 30 days. A total of 33 patients underwent liver transplantation and were excluded from survival analyses. A total of 130 had cirrhosis; 62, 50, and 18 had Child class A, B, and C disease, respectively. Forty-one patients had infiltrative HCC phenotype, 28 of whom also had PVI. Multivariate analysis of survival in all patients showed α-fetoprotein (AFP), performance status (PS), RAdv HCC, Child classification, albumin level, and ascites to predict survival. In patients without RAdv HCC, AFP, PS, Child classification, albumin level, and International Normalized Ratio were independent predictors. Increased bilirubin level was not an independent risk factor for death. CONCLUSIONS: Independent prognostic factors in patients with HCC undergoing DEB chemoembolization have been identified. Increased bilirubin level was not an independent risk factor. These data can be used in HCC patient selection and counseling for DEB chemoembolization.

The COX-2 pathway is essential during early stages of skeletal muscle regeneration.

Skeletal muscle regeneration comprises several overlapping cellular processes, including inflammation and myogenesis. Prostaglandins (PGs) may regulate muscle regeneration, because they modulate inflammation and are involved in various stages of myogenesis in vitro. PG synthesis is catalyzed by different isoforms of cyclooxygenase (COX), which are inhibited by nonsteroidal anti-inflammatory drugs. Although experiments employing nonsteroidal anti-inflammatory drugs have implicated PGs in tissue repair, how PGs regulate muscle regeneration remains unclear, and the potentially distinct roles of different COX isoforms have not been investigated. To address these questions, a localized freeze injury was induced in the tibialis anterior muscles of mice chronically treated with either a COX-1- or COX-2-selective inhibitor (SC-560 and SC-236, respectively), starting before injury. The size of regenerating myofibers was analyzed at time points up to 5 wk after injury and found to be decreased by SC-236 and in COX-2(-/-) muscles, but unaffected by SC-560. In contrast, SC-236 had no effect on myofiber growth when administered starting 7 days after injury. The attenuation of myofiber growth by SC-236 treatment and in COX-2(-/-) muscles is associated with decreases in the number of myoblasts and intramuscular inflammatory cells at early times after injury. Together, these data suggest that COX-2-dependent PG synthesis is required during early stages of muscle regeneration and thus raise caution about the use of COX-2-selective inhibitors in patients with muscle injury or disease.

Calcineurin initiates skeletal muscle differentiation by activating MEF2 and MyoD.

Skeletal muscle differentiation is characterized by withdrawal from the cell cycle, expression of muscle specific genes, fusion into multinucleated cells, and assembly of the contractile apparatus. Although many of the key regulatory elements have been identified, the factors that initiate the differentiation process are not well understood. The calcium-dependent phosphatase calcineurin plays an important regulatory role early in myogenesis, but the downstream effectors of calcineurin in differentiation are not known. Here, we show that calcium and calcineurin regulate expression of the myogenin gene at the level of transcription. The myogenin promoter contains two essential elements; an E-box and an A/T rich element that bind MRF and MEF2 transcription factors, respectively. Both of these elements are responsive to calcium and calcineurin. In differentiating myoblasts, MyoD is the major MRF protein that binds to the myogenin promoter E-box. Calcineurin activates MyoD indirectly by decreasing the expression of the Id inhibitory proteins, probably by down-regulating Egr-1 expression, an upstream activator of Id transcription. These results demonstrate that calcineurin regulates skeletal muscle differentiation by activating MEF2 and MyoD transcription factors leading to the induction of myogenin expression.

Regeneration of transgenic skeletal muscles with altered timing of expression of the basic helix-loop-helix muscle regulatory factor MRF4.

In regenerating muscle cells, muscle regulatory factor (MRF) 4 is normally the last of the four MRFs to be expressed. To analyze how the timing of MRF4 expression affects muscle regeneration, we compared regeneration after local freeze injury of muscles from wild-type mice with muscles from transgenic mice in which MRF4 expression was under control of an approximately 1.6-kb fragment of the myogenin promoter. Three days after injury, masseter and tibialis anterior (TA) muscles in wild-type mice expressed little or no MRF4 mRNA; whereas these muscles in transgenic mice expressed abundant MRF4 mRNA from both the transgene and the endogenous gene. Thus, MRF4 up-regulation was accelerated in transgenic compared to wild-type regenerating muscles, and expression of the transgene appeared to activate, perhaps indirectly, expression of the endogenous MRF4 gene. At 11 days after injury, regeneration, as measured by cross-sectional area and density of regenerated fibers, was significantly impaired in transgenic TA compared to wild-type TA, whereas at 19 days after injury both transgenic and TA muscle fibers had fully recovered to preinjury values. Regeneration of masseter muscles, which normally regenerate much less completely than TA muscles, was unaffected by the transgene. Thus, the timing of MRF4 up-regulation, as well as additional muscle-specific factors, can determine the progress of muscle regeneration.