Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. HCC initiates as a consequence of chronic liver damage and inflammation caused by hepatitis B and C virus infections, excessive alcohol consumption, or non-alcoholic fatty liver disease (NAFLD). Until recently, no effective treatments for advanced HCC were available and the 5-year survival rate had remained below 8% for many years. New insights into the mechanisms that drive the development of NAFLD-related HCC indicate that loss of T-cell-mediated immunosurveillance plays a cardinal role in tumor growth and malignant progression, in addition to previously identified inflammation-driven compensatory proliferation. Recently completed groundbreaking clinical studies have shown that treatments that restore antitumor immunity represent a highly effective therapeutic option for approximately 20% of advanced HCC patients. Understanding the causes of inflammation-driven immunosuppression and immune system dysfunction in the 80% of patients who fail to reignite antitumor immunity despite treatment with checkpoint inhibitors should lead to further and even more dramatic improvements in HCC immunotherapy.
Blood pressure reactivity to stress in childhood has predicted development of hypertension 45 years later, so it is important to understand the characteristics of blood pressure reactivity in childhood. The present study assessed the 1-week and 6-month stability of systolic blood pressure reactivity to a 40-meter run stressor in preschool children. Sixty-three low-income children (mean age, 3.9 years) were assessed on four different days over a 6-month period. One-week stability (r = 0.39 to 0.50) and 6-month stability (r = 0.56) of reactive systolic blood pressure levels were highly significant. Reactive systolic blood pressure level was more stable than resting systolic or diastolic blood pressure in this sample. Sex, body mass index, family cardiovascular disease history, and child Type A behavior all were unrelated to systolic blood pressure reactivity. Systolic blood pressure reactivity to exercise appears to be an enduring characteristic that emerges in early childhood.
A new method for isolation of cDNA clones encoding sequence-specific DNA-binding proteins is described. This method, the one-hybrid system, is based on the use of reporter genes whose transcription can be activated through synthetic cis elements recognized by the sought-after DNA-binding protein. These reporter genes are used for in vivo screening of a library of cDNAs fused to a DNA fragment encoding the GAL4 activation domain. cDNA clones expressing the appropriate fusion proteins lead to activation of these reporter genes in transformed yeast cells. We have used this approach to isolate a mammalian cDNA clone encoding a sequence-specific DNA-binding protein that recognizes the metal response elements (MREs) of the metallothionein (MT) genes. The protein encoded by this cDNA, M96, shows similarity to the trithorax proteins. Expression of a functional DNA-binding form of M96 requires Zn2+ ions. The recombinant protein binds to several different MREs but fails to recognize nonfunctional mutant MREs. M96 may be involved in the activation of MT genes in response to heavy-metal ions.
The pertussis toxin (PTX) insensitive heterotrimeric G protein G12 has been implicated in mitogenesis and transformation, but its direct effectors remain unknown. To define potential signaling pathways utilized by G12, we expressed an activated mutant of its alpha subunit, Galpha12(Q229L), in HEK293 cells and examined its effects on Ras and mitogen-activated protein kinases (MAPKs). Transient expression of activated Galpha12 increased the percentage of Ras in the active, GTP-bound state, stimulated c-Jun NH2-terminal kinase (JNK) activity, and enhanced the transcriptional activity of c-Jun. Dominant negative Ras (N17Ras) inhibited Galpha12-mediated JNK activation in NIH3T3 cells but failed to do so in HEK293 cells. In contrast, dominant negative Rac (N17Rac1) inhibited JNK activation by Galpha12 in HEK293 cells as well as three other cell lines. In 1321N1 cells, where thrombin stimulates G12-dependent mitogenesis, coexpression of N17Rac1 or a dominant negative mutant of MEKK1 (MEKKDelta(K432M)) inhibits c-Jun/AP-1 sensitive reporter gene expression stimulated by thrombin or Galpha12. These data demonstrate that the alpha subunit of the heterotrimeric G protein G12, like tyrosine kinase growth factor receptors, activates Ras and recruits a signal transduction pathway involving the small GTP-binding protein Rac that leads to JNK activation.
