Background Emodin, a natural anthraquinone, has shown potential as an effective therapeutic agent in the treatment of many diseases including cancer. However, its clinical development is hindered by uncertainties surrounding its potential toxicity. The primary purpose of this study was to uncover any potential toxic properties of emodin in mice at doses that have been shown to have efficacy in our cancer studies. In addition, we sought to assess the time course of emodin clearance when administered both intraperitoneally (I.P.) and orally (P.O.) in order to begin to establish effective dosing intervals. Methods We performed a subchronic (12 week) toxicity study using 3 different doses of emodin (~ 20 mg/kg, 40 mg/kg, and 80 mg/kg) infused into the AIN-76A diet of male and female C57BL/6 mice (n = 5/group/sex). Body weight and composition were assessed following the 12-week feeding regime. Tissues were harvested and assessed for gross pathological changes and blood was collected for a complete blood count and evaluation of alanine transaminase (ALT), aspartate transaminase (AST) and creatinine. For the pharmacokinetic study, emodin was delivered intraperitoneally I.P. or P.O. at 20 mg/kg or 40 mg/kg doses to male and female mice (n = 4/group/sex/time-point) and circulating levels of emodin were determined at 1, 4 and 12 h following administration via liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis. Results We found that 12 weeks of low (20 mg/kg), medium (40 mg/kg), or high (80 mg/kg) emodin feeding did not cause pathophysiological perturbations in major organs. We also found that glucuronidated emodin peaks at 1 h for both I.P. and P.O. administered emodin and is eliminated by 12 h. Interestingly, female mice appear to metabolize emodin at a faster rate than male mice as evidenced by greater levels of glucuronidated emodin at the 1 h time-point (40 mg/kg for both I.P. and P.O. and 20 mg/kg I.P.) and the 4-h time-point (20 mg/kg I.P.). Conclusions In summary, our studies establish that 1) emodin is safe for use in both male and female mice when given at 20, 40, and 80 mg/kg doses for 12 weeks and 2) sex differences should be considered when establishing dosing intervals for emodin treatment.

Gastrointestinal (GI) cancers cause one-third of all cancer-related deaths worldwide. Natural compounds are emerging as alternative or adjuvant cancer therapies given their distinct advantage of manipulating multiple pathways to both suppress tumor growth and alleviate cancer comorbidities; however, concerns regarding efficacy, bioavailability, and safety are barriers to their development for clinical use. Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a Chinese herb-derived anthraquinone, has been shown to exert anti-tumor effects in colon, liver, and pancreatic cancers. While the mechanisms underlying emodin’s tumoricidal effects continue to be unearthed, recent evidence highlights a role for mitochondrial mediated apoptosis, modulated stress and inflammatory signaling pathways, and blunted angiogenesis. The goals of this review are to (1) highlight emodin’s anti-cancer properties within GI cancers, (2) discuss the known anti-cancer mechanisms of action of emodin, (3) address emodin’s potential as a treatment complementary to standard chemotherapeutics, (4) assess the efficacy and bioavailability of emodin derivatives as they relate to cancer, and (5) evaluate the safety of emodin.

Weight fluctuations are common among individuals with obesity and are associated with increased morbidity. We examined adipose tissue immune and inflammatory markers in mice following weight loss and partial weight regain. Male C57BL/6 mice were randomized into four groups (n=8-10/group): low-fat diet for 32 weeks (LFD), high-fat diet for 32 weeks (HFD), LFD for 28 weeks then changed to a HFD for 4 weeks (LFD->H), HFD for 21 weeks then changed to LFD for 7 weeks and then changed to HFD for 4 weeks (HFD->L->H). LFD->H and HFD->L->H mice did not differ in body weight, fat mass, or fat percentage; however, these parameters were greater than in LFD (p<0.05), but lower than HFD (p<0.05). HFD->L->H had smaller adipocytes compared to HFD and LFD->H (p<0.05), but not LFD. Expression of CD11c and CD8a genes were elevated in epididymal fat of HFD->L->H compared to LFD->H and LFD (p<0.05). However, CD11c was lower in HFD->L->H compared to HFD (p<0.05) but there was no difference in CD8a between these groups. TNFα and IFNγ expression were increased in HFD->L->H compared to LFD and LFD->H (p<0.05); although HFD->L->H had lower expression of these cytokines compared to HFD (P<0.05). IL-1β was greater in HFD->L->H compared to LFD (p<0.05) but was not different from LFD->H or HFD. MCP1 was lower (p<0.05) in HFD->L->H compared to LFD->H. These data reinforce the importance of maintaining a body weight in the range that is recommended for optimal health to reduce immune and inflammatory perturbations associated with obesity.

A cachexia diagnosis is associated with a doubling in hospital stay and increased healthcare cost for cancer patients and most cachectic patients do not survive treatment. Unfortunately, complexity in treating cachexia is amplified by both the underlying malignancy and the anti-cancer therapy which can independently promote cachexia. Quercetin, an organic polyphenolic flavonoid, has demonstrated anti-inflammatory and antioxidant properties with promise in protecting against cancer and chemotherapy-induced dysfunction; however, whether quercetin is efficacious in maintaining muscle mass in tumor-bearing animals receiving chemotherapy has not been investigated. C26 tumor-bearing mice were given 5-fluorouracil (5FU; 30 mg/kg of lean mass i.p.) concomitant with quercetin (Quer; 50 mg/kg of body weight via oral gavage) or vehicle. Both C26 + 5FU and C26 + 5FU + Quer had similar body weight loss; however, muscle mass and cross-sectional area was greater in C26 + 5FU + Quer compared to C26 + 5FU. Additionally, C26 + 5FU + Quer had a greater number and larger intermyofibrillar mitochondria with increased relative protein expression of mitochondrial complexes V, III, and II as well as cytochrome c expression. C26 + 5FU + Quer also had increased MFN1 and reduced FIS1 relative protein expression without apparent benefits to muscle inflammatory signaling. Our data suggest that quercetin protected against cancer and chemotherapy-induced muscle mass loss through improving mitochondrial homeostatic balance.

Approximately one‐third of all breast cancer mortality results from metastatic recurrence after initial success of surgery and/or therapy. Although primary tumor removal is widely accepted as beneficial, it has long been suspected that surgery itself contributes to accelerated metastatic recurrence. We investigated surgical wounding's impact on tumor progression and lung metastasis in a murine model of triple negative breast cancer (TNBC). Ten‐week‐old female mice were inoculated with 4 T1 cells (week 0) and were either subjected to a 2 cm long cutaneous contralateral incision (wounded) or control (non‐wounded) on week 2 and monitored for 3 weeks (week 5). Mice with surgical wounding displayed significantly accelerated tumor growth observable as early as 1‐week post wounding. This was confirmed by increased tumor volume and tumor weight, post‐mortem. Further, surgical wounding increased metastasis to the lungs, as detected by IVIS imaging, in vivo and ex vivo (week 5). As expected then, wounded mice displayed decreased apoptosis and increased proliferation in both the primary tumor and in the lungs. Flow cytometry revealed that primary tumors from wounded mice exhibited increased tumor associated macrophages and specifically M2‐like macrophages, which are important in promoting tumor development, maintenance, and metastasis. Immunofluorescence staining and gene expression data further confirms an increase in macrophages in both the primary tumor and the lungs of wounded mice. Our data suggests that surgical wounding accelerates tumor progression and lung metastasis in a mouse model of TNBC, which is likely mediated, at least in part by an increase in macrophages.