We present evidence here that abundantly expressed b-catenin-triggered NF-kB-dependent upregulation of inducible nitric oxide synthase(iNOS) found in hepatoma Mahlavu cells (RT-resistant variant designated as RR-Mal), but not in Hep 3B cells (RT-sensitive variant designated as RS-3B) is a key element contribrting to the radioresisitance through the activation of two prominent radioprotective pathways. First, high iNOS expression found in RR-Mal, but not in RS-3B cells was found to perturb calcium homeostasis that triggered ER stress response leading to the overproduction of ER chaperone GRP-78 via robust generation of cleaved ATF-6a (50 kDa) subunits and their nuclear translocation. Meanwhile, both abundantly expressed NF-κB and COX-2 found in RR-Mal cells could also provoke an increased production of PGE2 resulting in robust production of Bcl-2. Interestingly, when RR-Mal cells were treated with PDTC (a NF-κB inhibitor) or celecoxib (a COX-2 inhibitor), a concentration-dependent downregulation of Bcl-2 could be demonstrated implying that Bcl-2 overexpression was indeed mediated through NF-κB/Cox-2/PGE2 pathway. Importantly, we also unveiled that siRNA-mediated silencing of survivin in RR-Mal cells could result in a concomitant downregulation of GRP-78 due to a severe inhibition of ATF-6a (50 kDa) expression. Taken together, our data demonstrate that constitutively overexpressed b-catenin/NF-κB/iNOS and NF-κB/COX-2/PGE2 pathways that overproducing GRP-78, survivin and Bcl-2 expressions are responsible for radioresistance acquisition in RR-Mal cells. Thus, both pathways could be served as potential targets for overcoming radioresistance.
Hepatocellular carcinoma (HCC) is the most common type of liver cancer and is also highly metastatic. Metastasis is considered to be the major cause of death in cancer patients. Resveratrol (3,5,4′-trihydroxystilbene) and related analogues have been reported as candidates to prevent cancer growth and invasion. The bioactivity of resveratrol-related analogues could be altered due to the presence and positioning of methoxy groups on the basic resveratrol chemical structure. This study investigated the effects and mechanism of action of resveratrol and its methoxy analogues on invasion of human hepatocarcinoma cells. The migratory and invasive abilities of phorbol 12-myristate 13-acetate (PMA)-treated HepG2 and PMA-untreated Hep3B cells were both reduced in a dose-dependent manner by treatment with resveratrol and 3,5,4′-trimethoxy-trans-stilbene (MR-3). Upon incubation of PMA-treated HepG2 cells with resveratrol (0−50 μM) or MR-3 (0−50 μM), the MMP-9 activity decreased but TIMP-1 protein increased in a dose-dependent manner. With resveratrol (0−50 μM) or MR-3 (0−1 μM) treatment on PMA-untreated Hep3B cells, both of the MMP-9 and MMP-2 activities decreased but TIMP-2 protein increased in a dose-dependent manner. These results suggest that resveratrol and its related methoxy analogue MR-3 might exert anti-invasive activity against hepatoma cells through regulation of MMP-2, MMP-9, TIMP-1, and TIMP-2. Further analysis with semiquantitative RT-PCR showed that the regulation of MMP-9 and TIMP-2 expressions by resveratrol and MR-3 in hepatoma cells may be on the transcriptional level but on the translational or post-translational level for TIMP-1.
In the last 20 years, the effects of advanced glycation end products (AGEs) on health have received increasing attention. High AGE levels in the body correlate with the progression of many diseases, such as diabetes, cardiovascular disease, and some cancers. However, whether AGEs are a cause of these diseases or represent accompanying symptoms of these diseases still needs to be elucidated by more comprehensive research. Recently, many researchers have begun to investigate the effects of AGE intake-induced variations of gut microbiota on disease progression, which will further explain the impact of AGEs on health and open a new chapter in AGE research.
Benign neurogenic tumors originating from the peripheral nervous system usually appear as schwannomas or neurofibromas. They represent one of the common causes of a posterior mediastinal mass and are usually found incidentally. However, tumors originating from the intrathoracic phrenic nerve are rare. We therefore report a case of schwannoma of the left phrenic nerve presenting as a lobulated mass causing hoarseness.
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