Research Progress of Liujunzi Decoction in the Treatment of Tumor-Associated Anorexia

Background

Cancer is one of the major public health problems around the world, according to the latest data from the International Agency for Research on Cancer, 19.3 million new cancer cases were diagnosed globally and nearly 10 million deaths occurred in 2020.¹ Although there are new cancer treatments such as biological therapy and targeted therapy, chemotherapy is one of the most effective and commonly used treatments. However, anorexia is one of the most common complications of advanced cancer patients and one of the most common side effects of antineoplastic agents, which will lead to adverse consequences such as reduced food intake, decreased body weight and affect the therapeutic effect of cancer.^2–6 Therefore, tumor-associated anorexia mainly includes cancerous anorexia (CA) caused by cancer itself, and chemotherapy-induced anorexia (CIA) caused by chemotherapeutic drugs.^7–10 At present, appetite stimulation, drug intervention and nutritional therapy are often used in the clinical treatment of tumor-associated anorexia, but the effect is unsatisfactory.^11,12 For example, progesterone such as megestrol acetate is often used in clinical practice to prevent and treat tumor cachexia. In addition to its efficacy in inhibiting tumor, this drug also has the efficacy of promoting appetite and improving anorexia, but it can lead to side effects such as venous thrombosis, sodium water retention, uterine bleeding, electrolyte disorder, and renal insufficiency.^13–15 Studies have shown that anamorelin and thalidomide have positive effects in the treatment of CA, but the mechanisms are not so clear and the high cost deters patients.^16,17 In view of the lack of effective drugs for CIA in clinical practice, it is urgent to develop safe and effective drugs for tumor-associated anorexia.¹⁸

Liujunzi decoction (LJZD), a classical tonifying prescription in traditional Chinese medicine (TCM), originates from the Yi Xue Zheng Zhuan compiled in the Ming Dynasty. It has the effect of benefiting vital energy and tonifying spleen, removing dampness to reduce phlegm, and mainly treats phlegm-dampness due to deficiency of the spleen syndrome. In 2008, an epoch-making study by Japanese scholars found that Rikkunshito could improve appetite in a cisplatin-induced anorexia model in rats by promoting the secretion of ghrelin, which immediately attracted the attention and research of a large number of scholars.^19,20 Clinical study found that LJZD and modified LJZD improved tumor-associated anorexia effectively.^18,21–33 A number of animal experiments have also proved that this prescription has the efficacy of preventing and treating tumor-associated anorexia.^19,34–41 In view of the exact effect of LJZD in improving tumor-associated anorexia, this paper summarizes the literature of LJZD in the treatment of tumor-associated anorexia from CA and CIA, in order to provide ideas for further application of LJZD.

CA and LJZD

CA is anorexia caused by advanced tumor. In advanced tumor often caused a complex systemic disease “cachexia”, leading to anorexia, weakness, muscle loss and anemia clinical features, cause to further reduce the quality of life.⁷ CA does not have a specific name in traditional Chinese medical science (TCMS). According to symptoms, it can be classified into the categories of “fullness”, “asthenia and fatigue”, “anorexia” or “insufficient food” in TCMS.⁴² Its etiology is mostly due to weakness of spleen and stomach, indigestion of diet, and emotional disorders, resulting in adverse middle energizer and abnormal ascending and descending.⁴² At the same time, it is also the cause of death in most advanced cancer patients, which directly affects the therapeutic effect of tumor, increases the incidence of complications, reduces the quality of life of cancer patients, and shortens the survival time.^7,43 The main pathological mechanism of CA is the disorder of food intake center and related peripheral signaling pathways.

Pathogenesis of CA: Central Nervous System, Peripheral Signals and Other Factors

In the arcuate nucleus (ARC) located at the bottom of the medial hypothalamus, there are two types of neurons regulating metabolism: one inhibits appetite, such as the neurons secreting proopiomelanocortin (POMC), the other promotes appetite, such as neurons secreting neuropeptide Y (NPY) and Agouti-related protein (AgRP).⁴⁴ According to the literature, the studies on inhibiting appetite neurons POMC mainly through influence are as follows. Under cachexia conditions, radiolabelled recombinant human lipocalin-2 (LCN2) was injected into macaques and found LCN2 can cross the blood–brain barrier and reach to the hypothalamus, regulating food intake by affecting AgRP/POMC neurons and leading to anorexia.^45,46 Under cancer cachectic conditions, POMC neurons can be activated by 5-hydroxytryptamine (5-HT) and produce satiety by releasing the shearing product α-melanin stimulating hormone (α-MSH) of POMC.^47,48 Hypothalamus has the function of mediating energy balance in the body, so hypothalamus dysfunction caused by inflammation can lead to the occurrence of CA, such as the activation of hypothalamic-pituitary-adrenal axis induced by interleukin-1β (IL-1β), which promotes the development of cancer anorexia-cachexia syndrome (CACS).^49,50 At the same time, it also up-regulates 5-HT levels to enhance the activity of hypothalamic anorexia neurons to some extent, stimulate POMC neurons, induce appetite decline and reduce food intake.^51,52 In addition, pro-inflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) and interferon-γ (IFN-γ) may directly enter the central nervous system through the blood–brain barrier and bind to the corresponding receptors in the hypothalamus to promote the development of anorexia.^53,54 To appetite-promoting neurons NPY, in vitro hypothalamic cell experiment showed that 5-HT could interfere with the synthesis, transportation and secretion of NPY, which could enhance food intake, that is, the anorexia caused by 5-HT under the condition of cancer cachexia may be related to the NPY system.⁴⁸ On the other hand, there are other factors that do not directly affect appetite-regulated neurons that can cause CA. Studies have shown that in the early stage of cancer development, the parasympathetic nervous system can perceive tumor signals and stimulate hypothalamic histaminergic neurons, prompting them to emit abnormal histamine signals.⁵⁵ The abnormal histamine signal acts on the histamine H1 receptor (HRH1) in the arcuate nucleus, medial nucleus and paraventricular nucleus of the hypothalamus. The activation of HRH1 receptor can mediate the activation of AMP-activated protein kinase (AMPK) in the hypothalamus, further inhibit the histamine H3 receptor (HRH3), thereby inhibiting the hypothalamic starvation center and inducing CA.^56,57 In one word, the main pathway of tumor leading to CA by affecting the central nervous system is to promote the secretion of related proteins and inflammatory factors, thereby abnormally regulating appetite-related neurons in the hypothalamus and activating appetite-related receptors.

Peripheral signals mainly involved in regulating appetite include leptin and ghrelin.⁵⁴ Leptin regulates appetite mainly by interacting with hypothalamic neuroendocrine pathways, inhibiting appetite regulation-related peptides such as NPY and orexin-A (OX-A) and stimulating hormones such as POMC.⁵⁸ Ghrelin can improve appetite, prevent weight loss, and promote the production of synthetic metabolic factors such as insulin and insulin-like growth factor 1 by stimulating growth hormone secretagogue receptor-1a (GHS-R1a) to promote the increase of synthetic metabolic hormones.^59–61 Glucagon-like peptide-1 (GLP-1) secreted mainly by colon L cells is expressed in nucleus tractus solitarius (NTS), which is related to nausea and anorexia. Studies have found that the use of GLP-1 receptor antagonist exendin-9 and the knockout of GLP-1 expression genes in NTS can effectively improve food intake and the body weight of CACS model rats.⁶² Leukemia inhibitory factor (LIF) secreted by tumor induces adipocyte lipolysis and increases serum IL-6 and leptin levels by activating the janus kinase/signal transducer and activator of tran-ions (JAK/STAT) signaling pathway and affected cachexia-related fat consumption and anorexia.^63,64 In summary, tumor mainly causes CA by affecting peripheral leptin, ghrelin, GLP-1 and LIF secretion and activating their central receptors.

In addition, central histamine neurons are closely related to the basic functions of the body, such as regulation behavior, biological rhythm, body temperature and food intake. For example, taste and olfactory functions are controlled by the brain discrete structures with different histaminergic neurons as targets. Abnormal histamine signals can lead to taste and olfactory disorders, thus triggering CA.⁷ On the other hand, the mechanical obstruction of gastrointestinal tract, delayed gastric emptying, digestive and absorption disorders and abnormal fluid loss caused by tumor growth and oppression of surrounding organs can lead to reduced food intake.⁴³ Figure 1 summarizes the main pathological mechanisms of CA.

Figure 1 The main pathological mechanisms of CA.

Clinical Application and Mechanism of LJZD in Prevention and Treatment of CA

Table 1 summarizes the main indexes of LJZD in the study of CA. Korean scholar Kang et al²¹ in a pilot, randomized, controlled study program, the selected subjects were randomly divided into two groups: control group and Yukgunja-Tang (LJZD in Korean herbal medicine) group. Through nutritional inquiry and leptin, TNF-α, ghrelin and IL-6 levels of detection, they found that LJZD in the treatment of tumor-associated anorexia has exerted efficacy and safety. Xie et al²² in the use of thalidomide, LJZD combined with transcatheter arterial chemoembolization in the treatment of advanced liver cancer clinical research found that LJZD can improve the appetite of patients, enhance their physique, and reduce the incidence of severe liver function damage. Zhan et al²³ in a clinical trial, the patients in the study group were treated with Xiangsha Liujunzi Decoction combined with auricular acupressure beans and megestrol acetate, while the patients in the control group were treated with megestrol acetate; Wang et al²⁴ divided the patients diagnosed as stage IV advanced malignant tumor patients with cachexia syndrome into the medroxyprogesterone group, the modified Xiangsha Guishao Liujunzi Decoction group and the modified Xiangsha Guishao Liujunzi Decoction combined with medroxyprogesterone group; Sun et al²⁵ randomly divided tumor patients who met the experimental criteria into the comprehensive group, the TCM group and the control group and treated them with Xiangsha Liujunzi Decoction combined with auricular point pressing beans and medroxyprogesterone; Cheng et al²⁶ divided 60 patients with advanced cancer into treatment group with megestrol acetate and treatment group with modified LJZD combined with megestrol acetate. In the above clinical studies, the analysis results showed that the appetite, weight and Karnofsky performance scale (KPS) scores of the patients treated with LJZD were improved, and the clinical symptoms of TCM changed well. There were no other side effects, and the patient’s anorexia was abated and the quality of life was improved.

Table 1 The Effect of LJZD on the Main Evaluation in CA Study

LJZD is effective in alleviating CA in clinical practice, but its mechanism still needs further exploration. Ohbuchi et al³⁴ performed plasma metabolomics analysis on AH-130 ascites-induced cachexia rat model. A total of 110 metabolites were detected in the plasma. LJZD treatment significantly changed the levels of 23 metabolites. It was found that LJZD can delay weight loss, improve muscle atrophy, reduce ascites content, and alleviate inflammation and anorexia by increasing glucarate in the plasma. Fujitsuka et al³⁵ established the AH-130 tumor-bearing anorexia rat model and found that 5-HT in hypothalamus reduced the ghrelin signal caused by the excessive interaction between 5-HT2C receptor and corticotropin-releasing factor (CRF), resulting in anorexia. 5-HT2C receptor antagonist could reduce the CRF level in hypothalamus, thereby increasing the plasma acylated ghrelin level to improve appetite. The experimental results show that LJZD not only has the efficacy of improving anorexia in tumor-bearing rats but also has the efficacy of improving gastrointestinal motility disorder, alleviating muscle atrophy, relieving anxiety and prolonging the survival time of tumor-bearing rats. It is an effective drug for the treatment of CASC. Terawaki et al³⁶ established a rat model of cachexia by inoculating rats with human gastric cancer 85As2 cells. They found that ghrelin resistance in tumor-bearing rats was one of the causes of anorexia and weight loss. Rikkunshito may improve CA by enhancing the ghrelin signaling pathway to reduce its resistance.

CIA and LJZD

Chemotherapy is effective for cancer, but with various side effects, including anorexia, nausea, vomiting, diarrhea and neurotoxicity, it makes it difficult for patients to continue treatment, resulting in poor prognosis and poor quality of life, further limiting the clinical application of chemotherapy.^65,66 Chemotherapy is one of the most effective methods for cancer treatment, and CIA is one of the serious adverse reactions caused by chemotherapy. CIA occurs in 50% of newly diagnosed cancer patients and up to 70% of patients with advanced diseases.⁶⁷ Although various countermeasures have been developed to prevent or treat side effects such as anorexia, the effect is unsatisfactory.^68,69 The pathological mechanism of CIA is related to many factors, especially the physiological mechanism disorder of appetite regulation center.

Pathogenesis of CIA: Central Nervous System, Peripheral Signals and Inflammatory Factors

NPY and ghrelin, which play roles in hypothalamic arcuate nucleus, are effective appetite inducers. Cisplatin, a chemotherapeutic drug, can reduce the concentration of Ca²⁺ in cells in arcuate nucleus and reduce the activity of NPY and ghrelin-responsive neurons to produce CIA.⁷⁰ At the same time, chemotherapy drugs cisplatin and 5-fluorouracil can reduce the level of ghrelin and inhibit the activity of GHS-R1a receptor in hypothalamus, thereby causing anorexia.⁹ In the delayed phase of chemotherapy, cisplatin activates GLP-1 neurons in NTS and leads to CIA. Experiments show that the injection of GLP-1 receptor antagonist in the fourth ventricle of the rat model of chemotherapy-induced anorexia can reduce cisplatin-induced anorexia, weight loss and kaolin intake.⁷¹ In the CIA rat model, it was found that cisplatin could induce the expression of fos-like immune response in the supraoptic nucleus and paraventricular nucleus, while oxytocin (OT) receptor antagonist could inhibit the expression of fos and improve anorexia.⁷² Studies have shown that cisplatin can affect neuronal γ oscillation, induce abnormal coupling of γ phase amplitude in ARC neurons, and activate the nitrosation stress caused by caspase-1 in neurons, resulting in CIA.⁷³ Overall, chemotherapy drugs such as cisplatin can reduce the activity of feeding-promoting neurons in the hypothalamus or induce abnormal neuronal responses leading to CIA.

It was found that the growth differentiation factor-15 (GDF-15) level in the cycle of cancer patients receiving platinum-based chemotherapy was high. Through the experiments of GDF-15 gene knockout mice and GDF-15 neutralizer treatment, the results showed that anorexia and weight loss caused by platinum-based treatment could be alleviated.¹⁰ Japanese scholars have found through experiments that cutting off the vagus nerve of rats can reduce the level of acylated ghrelin in plasma, and cisplatin can further reduce the level of acylated ghrelin and cause anorexia.^19,20 Subsequently, the administration of ghrelin in rats can improve the reduction of food intake caused by cisplatin. Peripheral factor ghrelin signaling pathway is the most studied in CIA, and GDF-15 related pathway has gradually entered scholars’ vision.

The use of chemotherapy drugs can promote the production of inflammatory cytokines and lead to CIA. Cisplatin activates histamine H4 receptor (HRH4) to release TNF-α and IL-1β in cells, which promotes the degradation of prepro-orexin (PPO) mRNA and leads to CIA.^74,75 At the same time, TNF-α can also induce the ubiquitination of orexin receptor 2 (OXR2), and the expression of OXR2 protein is reduced to reduce food intake.⁷⁶ Figure 2 summarizes the main pathological mechanisms of CIA.

Figure 2 The main pathological mechanisms of CIA.

Clinical Application and Mechanism of LJZD in Prevention and Treatment of CIA

Table 2 summarizes the main indexes of LJZD in the study of CIA. With the wide application of 5-HT3 receptor antagonist and NK-1 receptor antagonist, the adverse reactions such as nausea and vomiting caused by chemotherapy have been effectively controlled. However, the anorexia caused by chemotherapy has not been well controlled. Therefore, it is necessary to find and explore new therapeutic drugs and schemes. Nishida et al²⁷ observed the changes of the ratio of total ghrelin and acylated ghrelin in the study of gastric emptying disorder after gastric cancer surgery. The results showed that LJZD could inhibit the inactivation of acylated ghrelin, improve its plasma concentration and promote the appetite of patients. Huang et al²⁸ randomly divided malignant tumor patients with moderate-to-severe anorexia after systemic chemotherapy into the treatment group and the control group. The treatment group was given Xiangsha Liujunzi Decoction, and the control group was given medroxyprogesterone tablets; Sun et al²⁹ will be advanced non-small cell lung cancer (NSCLC) patients were divided into concurrent chemotherapy with cisplatin-based combined with modified LJZD treatment group and only received cisplatin-based chemotherapy in patients with control group; Yoshiya et al³⁰ randomly divided lung cancer patients into two groups, the treatment group took Rikkunshito, and the control group did not. All patients were given cisplatin on the first day of the experiment and combined with 5HT3, NK1 receptor antagonists and steroids for treatment; Ohnishi et al³¹ will accept cisplatin and paclitaxel treatment of cervical cancer or cervical cancer patients were randomly divided into LJZD group and control group (simple antiemetic drugs); Ohno et al³² randomly divided patients with gastric cancer into two groups. Group A (n = 5) took LJZD orally from the first course of treatment, and the second course of treatment did not take Rikkunshito tablets. Group B (n = 5) received reverse sequence therapy, and all patients received S-1 combined with cisplatin chemotherapy. In the above clinical studies, after evaluating the oral intake, the grade of anorexia, nausea and vomiting, and the concentration of acylated ghrelin in plasma, it was found that LJZD did not reduce the effective rate of chemotherapy and did not increase the incidence of hematological, hepatorenal toxicity and other side effects, which could effectively prevent cisplatin-induced anorexia, and its efficacy was equivalent to that of medroxyprogesterone acetate tablets. In a prospective, randomized, crossover trial of a lung cancer patient receiving cisplatin chemotherapy and an esophageal cancer patient receiving cisplatin chemotherapy, Rikkunshito increased plasma ghrelin levels and effectively alleviated CIA.^18,33

Table 2 The Effect of LJZD on the Main Evaluation in CIA Study

It has been reported that some TCM have no effect on the pharmacokinetics or anti-tumor effect of chemotherapeutic drugs in animal experiments, indicating that these TCM can be used in combination with chemotherapeutic drugs without reducing the efficacy of chemotherapy. Therefore, in the future, TCM may be more and more used as treatment for side effects of chemotherapy.⁷⁷ With the clinical application of LJZD more and more widely, the mechanism of its prevention and treatment of CIA is also being studied. Takeda et al¹⁹ compared with cisplatin model group, 5-HT2B/2C receptor agonist group and LJZD group found that LJZD can inhibit cisplatin-induced plasma levels of ghrelin and alleviate the loss of appetite in rats. At the same time, the author speculated that flavonoids contained in LJZD may inhibit the activity of 5-HT2B/2C receptor and promote the release of ghrelin, thereby improving cisplatin-induced gastrointestinal dysfunction. Yakabi et al³⁷ found that 5-HT2C receptor antagonist and Rikkunshito can enhance GHS-R1a signal transduction in hypothalamus to inhibit cisplatin-induced CIA by exploring the effect of ghrelin receptor expression in hypothalamus. Sadakane et al³⁸ explored whether Rikkunshito was involved in peripheral ghrelin degradation in CIA rat model, and found that multiple components (such as 10-gingerol) could inhibit ghrelin deacetylase activity, thereby increasing the level of acyl-ghrelin in plasma to alleviate CIA. Yoshimura et al³⁹ established anorexia rat model by cisplatin and treated with LJZD. The changes of regulatory peptides in hypothalamus were measured by in situ hybridization histochemical method. It was found that the treatment group could reduce the levels of POMC, cocaine and amphetamine-regulated transcript (CART) in arcuate nucleus and increase NPY. The results showed that LJZD had a therapeutic effect on cisplatin-induced anorexia. Zenitani et al⁴⁰ found that Rikkunshito could prevent cisplatin-induced intestinal mucosal injury by increasing intestinal epithelial cell proliferation and significantly reducing ileal cell apoptosis, thereby improving appetite and weight loss in CIA rats. Through metabolomics analysis, Dai et al⁴¹ found that inhibiting JAK-STAT signaling pathway, regulating the expression of anorexigenic and orexigenic peptides, and mediating multiple metabolic pathways may be the potential mechanism of LJZD in the treatment of CIA.

Discussion

In summary, TCM has played a favorable role in the treatment of various cancers as alternative therapy. TCM can not only alleviate the symptoms of tumor patients and improve their quality of life but also alleviate the adverse reactions and complications caused by chemotherapy, radiotherapy or targeted therapy.⁷⁸ Evidence from preclinical studies continues to support the view that TCM is effective in preventing or mitigating side effects caused by chemotherapy. More importantly, some reported TCM have no effect on pharmacokinetics or antitumor activity of chemotherapy agents in animal experiments, suggesting that they can be used in combination with chemotherapy without reducing their efficacy.⁷⁷ In one word, exploring effective TCM is conducive to the adjuvant treatment of cancer and provides useful information for the development of more effective anti-cancer treatment methods.

LJZD is a famous tonifying formula in TCM, which has been paid more and more attention by researchers because of its alleviation of adverse reactions (such as anorexia) in tumor treatment. LJZD and its modified prescription can treat anorexia by increasing appetite, protecting gastric mucosa and promoting secretion of digestive juice. By sorting out all the literature on the treatment of CA and CIA by LJZD in recent years, it is found that the main therapeutic mechanisms are to activate ghrelin signaling pathway, produce 5-HT2B/2C receptor-like antagonism and protect gastrointestinal mucosal barrier. Figure 3 summarizes the main mechanisms of LJZD in the treatment of CA and CIA. In addition, our laboratory conducted a multivariate chemometrics analysis of LJZD, combined with network pharmacology and molecular docking to construct drug and disease networks, and found that the main bioactive compounds in LJZD (especially ephedrine hydrochloride, hesperidin, ginsenoside rg1 and jujuboside A) may exert anti-inflammatory and anti-oxidative stress effects by interacting with sarcoma (SRC), phosphatidylinositol 3-kinase regulatory subunit alpha (PIK3R1), mitogen-activated protein kinase 1 (MAPK1), protein kinase b (AKT1) and other targets to treat CIA.⁷⁹

Figure 3 The main pathological mechanisms of LJZD in the treatment of CA and CIA.

Conclusion

However, there are still some imperfections in the study of LJZD. The composition of LJZD is complex, the target is numerous, the mechanism is unclear, and the sample size reported in clinical practice is small so that the persuasion is not strong. In recent years, many scholars have established CA^34,35,64,80 and CIA^19,39 animal models through various methods and explored their pathogenesis. It has been reported that GDF-15, GLP-1, NPY, HRH1, HRH4, central OT and microbe-gut-brain axis are related to tumor-associated anorexia, which may become a new research direction to explore LJZD in improving anorexia. Taken together, multidisciplinary research is needed to explore the pharmacodynamics and pharmacokinetics of Chinese herbal compound by using the joint analysis of transcriptome, metabolomics, genome and other multi-omics, so as to improve the credibility and repeatability of the research, which is of great significance for the clinical application and mechanism exploration of LJZD.