Cancer cachexia (CC), a syndrome characterized by anorexia and body weight loss due to low fat-free mass levels, including reduced musculature, markedly worsens patient quality of life. Although stomach cancer patients have the highest incidence of cachexia, few experimental models for the study of stomach CC have been established. Herein, we developed stomach CC animal models using nude rats subcutaneously implanted with two novel cell lines, i.e., MKN45c185, established from the human stomach cancer cell line MKN-45, and 85As2, derived from peritoneal dissemination of orthotopically implanted MKN45c185 cells in mice. Both CC models showed marked weight loss, anorexia, reduced musculature and muscle strength, increased inflammatory markers, and low plasma albumin levels; however, CC developed earlier and was more severe in rats implanted with 85As2 than in those implanted with MKN45cl85. Moreover, human leukemia inhibitory factor (LIF), a known cachectic factor, and hypothalamic orexigenic peptide mRNA levels increased in the models, whereas hypothalamic anorexigenic peptide mRNA levels decreased. Surgical removal of the tumor not only abolished cachexia symptoms but also reduced plasma LIF levels to below detectable limits. Importantly, oral administration of rikkunshito, a traditional Japanese medicine, substantially ameliorated CC-related anorexia and body composition changes. In summary, our novel peritoneal dissemination-derived 85As2 rat model developed severe cachexia, possibly caused by LIF from cancer cells, that was ameliorated by rikkunshito. This model should provide a useful tool for further study into the mechanisms and treatment of stomach CC. cachexia; leukemia inhibitory factor; rikkunshito; stomach cancer model; anorexia CANCER CACHEXIA, A MULTIFACTORIAL SYNDROME characterized by anorexia and the loss of body weight, adipose tissue, and skeletal muscle, is observed in 80% of advanced cancer patients and accounts for at least 20% of cancer-related deaths (20,35,42). This syndrome causes not only poor quality of life (QOL) but also poor responses to chemotherapy, highlighting the need for improved cancer cachexia treatments. Weight loss, the most prominent clinical feature of cachexia, is observed in 30 -80% of cancer patients, depending on tumor type. For example, weight loss occurs at a very high frequency (83%) in stomach and pancreatic cancer patients but is less prominent in patients with breast cancer, acute nonlymphocytic leukemia, and sarcomas (35). Although cachexia strongly impacts the success of therapeutic treatments, the mechanisms underlying this syndrome are not fully understood. Stomach cancer patients in particular have the highest incidence of cachexia; however, few experimental models for the study of stomach cancer cachexia have been established (4,14,66).A useful cachexia model must meet three of the following five diagnostic criteria in addition to weight loss: anorexia, decreased muscle strength, fatigue, low fat-free mass (FFM) index, and abnormal biochemistry (anemia, in...

Cancer cachexia (CC) is a multifactorial disease characterized by decreased food intake and loss of body weight due to reduced musculature with or without loss of fat mass. Patients with gastric cancer have a high incidence of cachexia. We previously established a novel CC rat model induced by human gastric cancer-derived 85As2 cells in order to examine the pathophysiology of CC and identify potential therapeutics. In patients with CC, anorexia is often observed, despite elevation of ghrelin, suggesting that ghrelin resistance may develop in these patients. In this study, we aimed to clarify the occurrence of ghrelin resistance in CC rats accompanied by anorexia and we investigated whether rikkunshito (RKT), a traditional Japanese Kampo medicine that potentiates ghrelin signaling, ameliorated CC-related anorexia through alleviation of ghrelin resistance. 85As2-tumor-bearing rats developed severe CC symptoms, including anorexia and loss of body weight/musculature, with the latter symptoms being greater in cachectic rats than in non-tumor-bearing or pair-fed rats. CC rats showed poor responses to intraperitoneal injection of ghrelin. In CC rats, plasma ghrelin levels were elevated and hypothalamic anorexigenic peptide mRNA levels were decreased, whereas hypothalamic growth hormone secretagogue receptor (GHS-R) mRNA was not affected. In vitro, RKT directly enhanced ghrelin-induced GHS-R activation. RKT administrated orally for 7 days partly alleviated the poor response to ghrelin and ameliorated anorexia without affecting the elevation of plasma ghrelin levels in CC rats. The expression of hypothalamic orexigenic neuropeptide Y mRNA but not hypothalamic GHS-R mRNA was increased by RKT. Thus, the 85As2 cell-induced CC rat model developed ghrelin resistance, possibly contributing to anorexia and body weight loss. The mechanism through which RKT ameliorated anorexia in the CC rat model may involve alleviation of ghrelin resistance by enhancement of ghrelin signaling. These findings suggest that RKT may be a promising agent for the treatment of CC.

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Cancer cachexia is highly prevalent in gastric cancer patients and characterized by decreased food consumption and body weight. We previously created a rat model of cancer cachexia using MKN45cl85 and 85As2 cells derived from human gastric cancer. The 85As2 cells induced cachexia more potently compared to MKN45cl85 cells. To clarify the mechanism underlying the difference in the cachexia-inducing ability of these cells, we conducted DNA microarray analysis, focusing on cell proliferation and the production of leukemia inhibitory factor (LIF), a cachexia-inducing factor. The plasma human LIF levels of 85As2-induced cachexic rats increased as symptoms worsened, whereas the plasma levels of MKNcl85 were low. 85As2 cells displayed more genetic changes compared to MKN45cl85 cells, which were related to Toll-like receptor (TLR) 4/5 signaling. Stimulation of both cells with TLR4 (lipopolysaccharide) or TLR5 (flagellin) agonists did not affect proliferation. However, in 82As2 cells, LIF production was significantly increased by stimulation with TLR5, which was suppressed by an inhibitor of interleukin-1 receptor-associated kinase-1/4, which are important factors in the TLR5 signaling pathway. The increase in LIF production resulting from activation of the TLR5 signaling pathway may contribute to the cachexia-inducing ability of 85As2 cells.

Despite the similar phenotypes, including weight loss, reduction of food intake, and lower adiposity, associated with caloric restriction (CR) and cancer cachexia (CC), CC is a progressive wasting syndrome, while mild CR improves whole body metabolism. In the present study, we compared adipose metabolic changes in a novel rat model of CC, mild CR (70% of the food intake of control rats, which is similar to the food consumption of CC rats), and severe CR (30% of the food intake of controls). We show that CC and severe CR are associated with much smaller adipocytes with significantly lower mitochondrial DNA content; but, that mild CR is not. CC and both mild and severe CR similarly upregulated proteins involved in lipolysis. CC also downregulated proteins involved in fatty acid biosynthesis, but mild CR upregulated these. These findings suggest that CC might impair de novo fatty acid biosynthesis and reduce mitochondrial biogenesis, similar to severe CR. We also found that rikkunshito, a traditional Japanese herbal medicine, does not ameliorate the enhanced lipolysis and mitochondrial impairment, but rather, rescues de novo fatty acid biosynthesis, suggesting that rikkunshito administration might have partially similar effects to mild CR.