Modified citrus pectin inhibits breast cancer development in mice by targeting tumor-associated macrophage survival and polarization in hypoxic microenvironment.

Large amounts of tumor-associated macrophages (TAM), which are predominately localized in hypoxia area of the tumor tissue, are associated with the malignant progression of the tumor. In the present study, we investigated the inhibitory effects of modified citrus pectin (MCP), a natural dietary polysaccharide, on the survival and polarization of TAM in relation to its inhibition on the growth and migration of breast cancer. M2 macrophages polarized from human monocyte THP-1 were chosen as a model for TAM. We showed that MCP (0.06%-1%) concentration-dependently suppressed the survival of TAM through inhibiting glucose uptake with a greater extent in hypoxia than in normoxia. Furthermore, MCP treatment decreased ROS level in TAM through its reducibility and inhibiting galectin-3 expression, leading to inhibition of glucose transporter-1 expression and glucose uptake. In addition, MCP suppressed M2-like polarization via inhibiting STAT3 phosphorylation. Moreover, the tumor-promoting effect of TAM could be restrained by MCP treatment as shown in human breast cancer MDA-MB-231 cells in vitro and in mouse breast cancer 4T1-luc orthotopic and metastasis models. In both tumor tissue and lung tissue of the mouse tumor models, the number of TAM was significantly decreased after MCP treatment. Taken together, MCP may be a promising agent for targeting TAM in tumor hypoxic microenvironment for breast cancer treatment.

Galectin-3 expression and secretion by tumor-associated macrophages in hypoxia promotes breast cancer progression.

Tumor-associated macrophages (TAMs) have been shown to be associated with poor prognosis of cancer and are predominately localized in the hypoxia regions of tumor. We demonstrated in this study that hypoxia increases the synthesis and secretion of galectin-3 by TAMs. The increased expression of galectin-3 in TAMs was seen to be associated with nucleation of transcription factor NF-κB through generation and activation of ROS and promoted tumor growth and metastasis in vitro and in mice through multiple molecular mechanisms. It was found that the TAMs-mediated promotion of tumor growth and metastasis in hypoxia was inhibited by administration of macrophage-depletion agent clodronate liposomal (CL) or galectin-3 inhibitor modified citric pectin (MCP) in orthotopic syngeneic mammary adenocarcinoma model and metastasis model. Co-administration of anti-angiogenesis agent sorafenib or bevacizumab with CL and MCP showed to cause stronger inhibition of tumor growth and metastasis than administration of each agent alone. These results indicate that hypoxia-induced galectin-3 expression and secretion from TAMs promotes tumor growth and metastasis. Targeting the actions of galectin-3 in hypoxia may be a potential therapeutic strategy for cancer treatment.

A mechanistic study on altered pharmacokinetics of irinotecan by St. John's wort.

Irinotecan (CPT-11) is an important anticancer drug in management of advanced colon cancer. A marked protective effect on CPT-11-induced blood and gastrointestinal toxicity is obtained by combination of St. John's wort (SJW) in recent clinical and rat studies. However, the mechanism is unclear. This study aimed to explore the effects of SJW on the pharmacokinetics of CPT-11 and its major metabolites (SN-38 and SN-38 glucuronide) in rats and the underlying mechanisms using several in vitro models. Short-term (3 days) and long-term (14 days) pretreatment with SJW were conducted in rats to examine the effects of co-administered SJW on the plasma pharmacokinetics of CPT-11, SN-38 and SN-38 glucuronide. Rat liver microsomes and a rat hepatoma cell line, H4-II-E cells, were utilized to study the effects of aqueous and ethanolic extracts (AE and EE) and major active components (hyperforin, hypericin and quercetin) of SJW on CPT-11 and SN-38 metabolism and intracellular accumulation. Co-administered SJW for consecutive 14 days significantly decreased the initial plasma concentration (C0) of CPT-11, the area under the concentration-time curve (AUC(0-10hr)) and maximum plasma concentration (Cmax) of SN-38. The ethanolic extracts (EE) of SJW at 5 microg/ml significantly decreased SN-38 glucuronidation by 45% (P < 0.05) in rat hepatic microsomes. Pre-incubation of aqueous SJW extracts (AE) at 10 microg/ml, SJW EE at 5 microg/ml, and quercetin at 10 microM significantly increased the glucuronidation of SN-38 in H4-II-E cells. A 2-hr pre-incubation of quercetin (100 microM) significantly increased the intracellular accumulation of CPT-11 (P < 0.05). However, pre-incubation of hypericin (20 nM and 200 nM) and hyperforin (1 microM) significantly decreased the intracellular accumulation of CPT-11. In addition, pre-incubation of hypericin, SJW EE and quercetin significantly increased the intracellular accumulation of SN-38. Aqueous and ethanolic SJW extracts and its major active components did not alter the plasma protein binding of CPT-11 and SN-38. These results indicated that the aqueous and ethanolic extracts of SJW and its major active components could markedly alter glucuronidation of SN-38 and intracellular accumulation of CPT-11 and SN-38, which probably provides partial explanation for the altered plasma pharmacokinetics of CPT-11 and SN-38 and the antagonizing effects on the toxicities of CPT-11. Further studies are needed to explore the role of both pharmacokinetic and pharmacodynamic components in the protective effect of SJW against the toxicities of CPT-11.

Drug-herb interactions: eliminating toxicity with hard drug design.

By searching the literatures, it was found that a total of 32 drugs interacting with herbal medicines in humans. These drugs mainly include anticoagulants (warfarin, aspirin and phenprocoumon), sedatives and antidepressants (midazolam, alprazolam and amitriptyline), oral contraceptives, anti-HIV agents (indinavir, ritonavir and saquinavir), cardiovascular drug (digoxin), immunosuppressants (cyclosporine and tacrolimus) and anticancer drugs (imatinib and irinotecan). Most of them are substrates for cytochrome P450s (CYPs) and/or P-glycoprotein (PgP) and many of which have narrow therapeutic indices. However, several drugs including acetaminophen, carbamazepine, mycophenolic acid, and pravastatin did not interact with herbs. Both pharmacokinetic (e.g. induction of hepatic CYPs and intestinal PgP) and/or pharmacodynamic mechanisms (e.g. synergistic or antagonistic interaction on the same drug target) may be involved in drug-herb interactions, leading of altered drug clearance, response and toxicity. Toxicity arising from drug-herb interactions may be minor, moderate, or even fatal, depending on a number of factors associated with the patients, herbs and drugs. Predicting drug-herb interactions, timely identification of drugs that interact with herbs, and therapeutic drug monitoring may minimize toxic drug-herb interactions. It is likely to predict pharmacokinetic herb-drug interactions by following the pharmacokinetic principles and using proper models that are used for predicting drug-drug interactions. Identification of drugs that interact with herbs can be incorporated into the early stages of drug development. A fourth approach for circumventing toxicity arising from drug-herb interactions is proper design of drugs with minimal potential for herbal interaction. So-called "hard drugs" that are not metabolized by CYPs and not transported by PgP are believed not to interact with herbs due to their unique pharmacokinetic properties. More studies are needed and new approached are required to minimize toxicity arising from drug-herb interactions.

St. John's wort attenuates irinotecan-induced diarrhea via down-regulation of intestinal pro-inflammatory cytokines and inhibition of intestinal epithelial apoptosis.

Diarrhea is a common dose-limiting toxicity associated with cancer chemotherapy, in particular for drugs such as irinotecan (CPT-11), 5-fluouracil, oxaliplatin, capecitabine and raltitrexed. St. John's wort (Hypericum perforatum, SJW) has anti-inflammatory activity, and our preliminary study in the rat and a pilot study in cancer patients found that treatment of SJW alleviated irinotecan-induced diarrhea. In the present study, we investigated whether SJW modulated various pro-inflammatory cytokines including interleukins (IL-1beta, IL-2, IL-6), interferon (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) and intestinal epithelium apoptosis in rats. The rats were treated with irinotecan at 60 mg/kg for 4 days in combination with oral SJW or SJW-free control vehicle at 400 mg/kg for 8 days. Diarrhea, tissue damage, body weight loss, various cytokines including IL-1beta, IL-2, IL-6, IFN-gamma and TNF-alpha and intestinal epithelial apoptosis were monitored over 11 days. Our studies demonstrated that combined SJW markedly reduced CPT-11-induced diarrhea and intestinal lesions. The production of pro-inflammatory cytokines such as IL-1beta, IFN-gamma and TNF-alpha was significantly up-regulated in intestine. In the mean time, combined SJW significantly suppressed the intestinal epithelial apoptosis induced by CPT-11 over days 5-11. In particular, combination of SJW significantly inhibited the expression of TNF-alpha mRNA in the intestine over days 5-11. In conclusion, inhibition of pro-inflammatory cytokines and intestinal epithelium apoptosis partly explained the protective effect of SJW against the intestinal toxicities induced by irinotecan. Further studies are warranted to explore the potential for STW as an agent in combination with chemotherapeutic drugs to lower their dose-limiting toxicities.

Monitoring of immune responses to a herbal immuno-modulator in patients with advanced colorectal cancer.

Many herbal medicines are widely used as immuno-modulators in Asian countries. Ganoderma lucidum (Lingzhi) is one of the most commonly used herbs in Asia and preclinical studies have established that the polysaccharide fractions of G. lucidum have potent immuno-modulating effects. However, clinical evidence for this is scanty. The present open-labeled study aimed to evaluate the effects of G. lucidum polysaccharides on selected immune functions in patients with advanced colorectal cancer. Forty-seven patients were enrolled and treated with oral G. lucidum at 5.4 g/day for 12 weeks. Selected immune parameters were monitored using various immunological methods throughout the study. In 41 assessable cancer patients, treatment with G. lucidum tended to increase mitogenic reactivity to phytohemagglutinin, counts of CD3, CD4, CD8 and CD56 lymphocytes, plasma concentrations of interleukin (IL)-2, IL-6 and interferon (IFN)-gamma, and NK activity, whereas plasma concentrations of IL-1 and tumor necrosis factor (TNF)-alpha were decreased. For all of these parameters, no statistical significance was observed when a comparison was conducted between baseline and those values after a 12-week treatment with G. lucidum. The changes of IL-1 were correlated with those for IL-6, IFN-gamma, CD3, CD4, CD8 and NK activity (p<0.05) and IL-2 changes were correlated with those for IL-6, CD8 and NK activity. The results indicate that G. lucidum may have potential immuno-modulating effect in patients with advanced colorectal cancer. Further studies are needed to explore the benefits and safety of G. lucidum in cancer patients.

[Adjuvant chemotherapy after orthotopic liver transplantation for advanced hepatocellular carcinoma].

OBJECTIVE: To investigate the feasibility, reliability and therapeutic effectiveness of adjuvant chemotherapy for advanced hepatocellular carcinoma (HCC) after orthotopic liver transplantation (OLT). METHODS: The clinical data of adjuvant chemotherapy after OLT in 10 advanced HCC patients were studied retrospectively. FAP chemotherapy regimen was adopted calcium folinate (CF) 200 mg/m(2) and 5-Fluorouracil 500 mg/m(2) iv on D1 to D5, and doxorubicin 40 mg/m(2), cisplatin 30 mg/m(2) iv on D1, with 28 days as a cycle. The opportune time of chemotherapy, chemotherapy regimen, synergistic action between cytotoxic agent and immunosuppressive agent on liver and kidney and side-effects were preliminarily evaluated. RESULTS: 7/10 patients are surviving, with the longest survival of 32 months, and the shortest 9 months. Three patients died after operation, two at 13 months, one at 20 months after OLT, all died of metastasis. The incidence of one year survival was 9/9. During the period of chemotherapy, the side-effects of adjuvant chemotherapy were moderate. CONCLUSION: Chemotherapy which is able to prolong the life-span of patients with advanced HCC after orthotopic liver transplantation is feasible and effective, the side-effects were mild. The choice of opportune time of chemotherapy might influence the outcome.