L-ascorbic acid (L-AA; vitamin C) induces apoptosis in cancer cells. This study aimed to elucidate the molecular mechanisms of L-AA-induced apoptosis in human laryngeal epidermoid carcinoma Hep-2 cells. L-AA suppressed the viability of Hep-2 cells and induced apoptosis, as shown by the cleavage and condensation of nuclear chromatin and increased number of Annexin V-positive cells. L-AA decreased Bcl-2 protein expression but upregulated Bax protein levels. In addition, cytochrome c release from the mitochondria into the cytosol and activation of caspase-9, -8, and -3 were enhanced by L-AA treatment. Furthermore, apoptosis-inducing factor (AIF) and endonuclease G (EndoG) were translocated into the nucleus during apoptosis of L-AA-treated Hep-2 cells. L-AA effectively inhibited the constitutive nuclear factor-κB (NF-κB) activation and attenuated the nuclear expression of the p65 subunit of NF-κB. Interestingly, L-AA treatment of Hep-2 cells markedly activated Akt and mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase 1/2, p38, and c-Jun N-terminal kinase [JNK]) and and LY294002 (Akt inhibitor), SB203580 (p38 inhibitor) or SP600125 (a JNK inhibitor) decreased the levels of Annexin V-positive cells. These results suggested that L-AA induces the apoptosis of Hep-2 cells via the nuclear translocation of AIF and EndoG by modulating the Bcl- 2 family and MAPK/Akt signaling pathways.

The fruit of Chaenomeles sinensis (Thouin) Koehne (Chaenomelis Fructus) known as “Mo-Gua” in Korea has been commonly used in traditional medicine to treat inflammatory diseases, such as sore throat. However, its effect on bone metabolism has not been elucidated yet. Here, we examined the effect of Chaenomelis Fructus ethanol extract (CFE) on receptor activator of nuclear factor (NF)-κB ligand (RANKL)-mediated osteoclast differentiation and formation. CF-E considerably inhibited osteoclast differentiation and tartrate-resistant acid phosphatase-positive multinuclear cell formation from bone marrow-derived macrophages and osteoclast precursor cells in a dose-dependent manner. In addition, the formation of actin rings and resorption pits were significantly suppressed in CF-E-treated osteoclasts as compared with the findings in non-treated control cells. Consistent with these phenotypic inhibitory results, the expressions of osteoclast differentiation marker genes (Acp5, Atp6v0d2 , Oscar, CtsK, and Tm7sf4) and Nfatc1 , a pivotal transcription factor for osteoclastogenesis, were markedly decreased by CF-E treatment. The inhibitory effect of CF-E on RANKL-induced osteoclastogenesis was associated with the suppression of NFATc1 expression, not by regulation of mitogen-activated protein kinases and NF-κB activation but by the inactivation of phospholipase C gamma 1 and 2. These results indicate that CF-E has an inhibitory effect on osteoclast differentiation and formation, and they suggest the possibility of CF-E as a traditional therapeutic agent against bone-resorptive diseases, such as osteoporosis, rheumatoid arthritis, and periodontitis.

The transcription factor nuclear factor-kB (NF-kB) plays an important role in regulating cell growth, apoptosis, and metastatic functions. Constitutive activation of NF-KB has been observed in various cancers; however, molecular mechanisms resulting in such activation remain elusive. Numerous evidences showed that over expression of TGase 2 might be linked with constitutive activation of NF-KB. To understand the pathways responsible for constitutive activation of NF-kB is important for rational design of NF-kB inhibitors for cancer therapy. Human salivary gland adenocarcinoma has been most aggressive solid tumors. Current therapy does not significantly improve survival rates. Thus, to investigate new therapeutic modalities against this adenocarcinoma is necessary. The purpose of this study was to study a constitutive activation of NF-kB with the expression of TG2 in SGT cell line origianted from human salivary gland adenocarcinoma by TGase 2 activity, RT-PCR and immunoslot blotting method. SGT cell line showed the highest TGase 2 activity and NF-kB activation than any other cell line. All the cell lines showed increased NF-kB mRNA activation after A231027 treatment than that of control. In immunoslot blotting, SGT cell line showed NF-kB activation correlated with TGase 2 expression after A231027 and BSA. It suggested that there might be a direct correlation between TGase 2 expression and NF-kB activation in SGT cell line.