lignans and Peritoneal-Neoplasms

There is increasing global incidence of highly metastatic melanoma and therapeutic strategies like those focusing on the downstream beta-catenin/MITF axis of invading melanoma cells are urgently needed. Targeting endoplasmic reticulum (ER) stress can promote cancer cell death and inhibit epithelial mesenchymal transition (EMT) in metastatic tumors. This study aimed to determine if Honokiol could promote ER stress-dependent apoptosis and regulate metastatic melanoma. The therapeutic efficacy of Honokiol was assessed using the highly metastatic melanoma xenograft mouse model for peritoneal metastasis and evaluated by computed tomography imaging. The ER stress marker, Calpain-10, delineated a novel proteolytic cleavage enzyme, while CHOP/GADD153-regulated apoptosis was used for gene silencing to determine the role of the β-catenin/MITF axis in melanoma cells. The results showed that Honokiol effectively decreased peritoneal dissemination and organ metastasis via ER stress activation and EMT marker inhibition. Knockdown Calpain-10 or CHOP/GADD153 blocked all of the biological effects in Honokiol-induced β-catenin/MITF cleavage, ERSE or TCF/LEF luciferase activity, and β-catenin kinase activity. These findings suggest that Honokiol can significantly thwart the progression of highly metastatic melanoma using the β-catenin/MITF axis via prompt Calpain-10 and CHOP/GADD153 regulated cascades.

Topics: Animals; Antineoplastic Agents, Phytogenic; beta Catenin; Biphenyl Compounds; Calpain; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclin-Dependent Kinase 2; Endoplasmic Reticulum Stress; Gene Expression Regulation, Neoplastic; Humans; Lignans; Male; Melanoma; Mice, Inbred BALB C; Mice, Nude; Microphthalmia-Associated Transcription Factor; Peritoneal Neoplasms; Skin Neoplasms; Transcription Factor CHOP; Wnt Signaling Pathway; Xenograft Model Antitumor Assays

Honokiol is known to suppress the growth of cancer cells; however, to date, its antiperitoneal dissemination effects have not been studied in an orthotopic mouse model. In the present study, we evaluated the antiperitoneal dissemination potential of Honokiol in an orthotopic mouse model and assessed associations with tumor growth factor-β1 (TGFβ1) and cells stimulated by a carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Our results demonstrate that tumor growth, peritoneal dissemination and peritoneum or organ metastasis of orthotopically implanted MKN45 cells were significantly decreased in Honokiol-treated mice and that endoplasmic reticulum (ER) stress was induced. Honokiol-treated tumors showed increased epithelial signatures such as E-cadherin, cytokeratin-18 and ER stress marker. In contrast, decreased expression of vimentin, Snail and tumor progression locus 2 (Tpl2) was also noted. TGFβ1 and MNNG-induced downregulation of E-cadherin and upregulation of Tpl2 were abrogated by Honokiol treatment. The effect of Tpl2 inhibition in cancer cells or endothelial cells was associated with inactivation of CCAAT/enhancer binding protein B, nuclear factor kappa-light-chain-enhancer of activated B cell and activator protein-1 and suppression of vascular endothelial growth factor. Inhibition of Tpl2 in gastric cancer cells by small interfering RNA or pharmacological inhibitor was found to effectively reduce growth ability and vessel density in vivo. Honokiol-induced reversal of epithelial-to-mesenchymal transition (EMT) and ER stress-induced apoptosis via Tp12 may involve the paralleling processes. Taken together, our results suggest that the therapeutic inhibition of Tpl2 by Honokiol thwarts both gastric tumor growth and peritoneal dissemination by inducing ER stress and inhibiting EMT.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Biphenyl Compounds; Blotting, Western; Cell Adhesion; Cell Movement; Cell Proliferation; Fluorescent Antibody Technique; Humans; Immunoenzyme Techniques; Immunoprecipitation; Lignans; Luciferases; Male; MAP Kinase Kinase Kinases; Mice; Mice, Inbred BALB C; Mice, Nude; Peritoneal Neoplasms; Phytotherapy; Proto-Oncogene Proteins; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stomach Neoplasms; Tumor Cells, Cultured