In Vivo Reversal of P-Glycoprotein-Mediated Drug Resistance in a Breast Cancer Xenograft and in Leukemia Models Using a Novel, Potent, and Nontoxic Epicatechin EC31.

The modulation of P-glycoprotein (P-gp, ABCB1) can reverse multidrug resistance (MDR) and potentiate the efficacy of anticancer drugs. Tea polyphenols, such as epigallocatechin gallate (EGCG), have low P-gp-modulating activity, with an EC50 over 10 µM. In this study, we optimized a series of tea polyphenol derivatives and demonstrated that epicatechin EC31 was a potent and nontoxic P-gp inhibitor. Its EC50 for reversing paclitaxel, doxorubicin, and vincristine resistance in three P-gp-overexpressing cell lines ranged from 37 to 249 nM. Mechanistic studies revealed that EC31 restored intracellular drug accumulation by inhibiting P-gp-mediated drug efflux. It did not downregulate the plasma membrane P-gp level nor inhibit P-gp ATPase. It was not a transport substrate of P-gp. A pharmacokinetic study revealed that the intraperitoneal administration of 30 mg/kg of EC31 could achieve a plasma concentration above its in vitro EC50 (94 nM) for more than 18 h. It did not affect the pharmacokinetic profile of coadministered paclitaxel. In the xenograft model of the P-gp-overexpressing LCC6MDR cell line, EC31 reversed P-gp-mediated paclitaxel resistance and inhibited tumor growth by 27.4 to 36.1% (p < 0.001). Moreover, it also increased the intratumor paclitaxel level in the LCC6MDR xenograft by 6 fold (p < 0.001). In both murine leukemia P388ADR and human leukemia K562/P-gp mice models, the cotreatment of EC31 and doxorubicin significantly prolonged the survival of the mice (p < 0.001 and p < 0.01) as compared to the doxorubicin alone group, respectively. Our results suggested that EC31 was a promising candidate for further investigation on combination therapy for treating P-gp-overexpressing cancers.

Knockdown of CCL28 inhibits endometriosis stromal cell proliferation and invasion via ERK signaling pathway inactivation.

Endometriosis (EM), the presence of functional endometrial glands and stroma outside the uterine cavity, is a common gynecological disorder. At present, the pathogenesis of EM has not been fully elucidated, so there is still a lack of effective therapy. The present study aimed to explore the role of C­C motif chemokine ligand 28 (CCL28) and its underlying mechanism in endometrial stromal cells to propose a novel therapy for EM treatment. The expression of CCL28 and CC chemokine receptor 10 (CCR10) were examined. After CCL28 knockdown or overexpression by lentivirus infection, cell proliferation and invasion were measured. It was revealed that compared with normal, the expression levels of CCL28 and CCR10 were significantly elevated in endometrial tissues of patients with EM. Knockdown of CCL28 in endometrial stromal cells significantly suppressed cell proliferation and invasion, and this was accompanied by significantly reduced expression levels of CCR10, MMP2, MMP9, integrin ß1 (ITGB1) and phosphorylated (p)­ERK/ERK ratio. The addition of the CCL28 recombinant protein had an opposite effect to CCL28 downregulation. Furthermore, the ERK inhibitor, PD98059, reduced CCL28­induced cell proliferation and invasion, as well as the expression levels of MMP2, MMP9, ITGB1 and p­ERK. Therefore, the present study indicated that CCL28 may contribute to the progression of EM by regulating MMP2, MMP9 and ITGB1 expression and function via the activation of the ERK signaling pathway.

Synthesis and evaluation of stereoisomers of methylated catechin and epigallocatechin derivatives on modulating P-glycoprotein-mediated multidrug resistance in cancers.

P-glycoprotein (P-gp; ABCB1)-mediated drug efflux causes multidrug resistance in cancer. Previous synthetic methylated epigallocatechin (EGC) possessed promising P-gp modulating activity. In order to further improve the potency, we have synthesized some novel stereoisomers of methylated epigallocatechin (EGC) and gallocatechin (GC) as well as epicatechin (EC) and catechin (C). The (2R, 3S)-trans-methylated C derivative 25 and the (2R, 3R)-cis-methylated EC derivative 31, both containing dimethyoxylation at ring B, tri-methoxylation at ring D and oxycarbonylphenylcarbamoyl linker between ring D and C3, are the most potent in reversing P-gp mediated drug resistance with EC50 ranged from 32 nM to 93 nM. They are non-toxic to fibroblast with IC50 > 100 µM. They can inhibit the P-gp mediated drug efflux and restore the intracellular drug concentration to a cytotoxic level. They do not downregulate surface P-gp protein level to enhance drug retention. They are specific for P-gp with no or low modulating activity towards MRP1- or BCRP-mediated drug resistance. In summary, methylated C 25 and EC 31 derivatives represent a new class of potent, specific and non-toxic P-gp modulator.

Effects of Dexmedetomidine on Patients Undergoing Laparoscopic Surgery for Colorectal Cancer.

BACKGROUND: Pneumoperitoneum during laparoscopic surgery has a systemic impact on the renal system and might contribute to acute kidney injury or postoperative renal dysfunction. However, effective preventive strategies are still lacking. We aimed to explore the effects of dexmedetomidine (DEX) on kidney and other organ function in patients undergoing elective laparoscopic surgery for colorectal cancer. MATERIALS AND METHODS: Fifty-six patients were randomly enrolled into the Control or DEX group. The DEX group received 1 µg kg-1 DEX intravenously within 10 min followed by a maintenance dose of 0.5 µg kg-1 h-1 infused until 30 min before closing the peritoneum. In the Control group, 0.9% sodium chloride was administered as a placebo. The primary outcome was serum neutrophil gelatinase-associated lipocalin (NGAL) levels reflecting kidney injury. Secondary outcomes included variables reflecting the kidney, intestinal injury and systemic inflammatory response. RESULTS: NGAL levels were significantly lower in the DEX group than in the Control group at 1 d and 5 d postoperatively (107.5 ± 55.6 ng mL-1versus 179.5 ± 78.2 ng mL-1; 70.3 ± 45.8 ng mL-1versus 135.2 ± 59.6 ng mL-1, P < 0.001), while the BUN and Cr levels showed no differences between the groups. Serum DAO activity was significantly lower in the DEX group patients 24 h after surgery. Moreover, I-FABP levels were markedly lower at 2 h and 24 h postoperatively in the DEX group than in the Control group (P < 0.001). CONCLUSIONS: Perioperative DEX administration may potentially confer kidney and intestinal protection during laparoscopic surgery for colorectal cancer patients.

Disruption of SND1-MTDH Interaction by a High Affinity Peptide Results in SND1 Degradation and Cytotoxicity to Breast Cancer Cells In Vitro and In Vivo.

Staphylococcal nuclease domain-containing protein 1 (SND1) is a multifunctional oncoprotein overexpressed in breast cancer. Binding of metadherin (MTDH) to SND1 results in the stabilization of SND1 and is important in the initiation and progression of breast cancer. Disruption of such interaction is a potential therapeutic for breast cancer. SN1/2 domain of SND1 was used as bait in a phage display screening to identify a 12-amino acid peptide 4-2. The activity of peptide 4-2 was evaluated by ELISA, coimmunoprecipitation, MTS, Western blot analysis, and xenograft mouse model. Peptide 4-2 could disrupt SND1-MTDH interaction. Cell penetrating derivative of peptide 4-2 (CPP-4-2) could penetrate and kill breast cancer cells by disrupting SND1-MTDH interaction and degrading SND1. Tryptophan 10 (W10) of peptide 4-2 was essential in mediating cytotoxicity, SND1 interaction, SND1-MTDH disruption, and SND1 degradation. CPP-4-2 could inhibit the growth of breast cancer in a xenograft mouse model. The SND1-interacting peptide 4-2 could kill breast cancer cells both in vitro and in vivo by interacting with SND1, disrupting SND1-MTDH interaction, and inducing SND1 degradation. W10 was an essential amino acid in the activity of peptide 4-2.

TRIM65 Promotes Invasion of Endometrial Stromal Cells by Activating ERK1/2/C-myc Signaling via Ubiquitination of DUSP6.

BACKGROUND: Endometriosis (EM) is a benign gynecological disease that shares some characteristics with malignancy, such as proliferation and invasion. So far, the pathogenesis of EM is still unclear. In this study, we investigated whether TRIM65 can play a role in the development of EM. METHODS: TRIM65 expression levels in eutopic, ectopic, and normal endometrium were detected by quantitative real-time PCR and Western blot. Cell proliferation and invasion of primary endometrial stromal (EMS) cells were detected by CCK-8 and Transwell analysis. The interaction between TRIM65 and DUSP6 or C-myc was measured by coimmunoprecipitation, ubiquitylation, dual luciferase, and chromatin immunoprecipitation analysis. RESULTS: We found that TRIM65 was identified as an up-regulated gene in ectopic endometrial tissues and EMS cells compared with control groups without EM. TRIM65 expression was positively correlated with the levels of p-ERK1/2, C-myc, matrix metalloproteinase-2, and integrin ß1 in ectopic endometrial tissues in patients and mice. TRIM65 promoted the cell proliferation and invasion of EMS cells via the ERK1/2/C-myc pathway through ubiquitination of DUSP6. C-myc promoted TRIM65 expression through inducing TRIM65 promoter activity. Additionally, the increased expression of TRIM65, C-myc, matrix metalloproteinase-2, integrin ß1, and p-ERK1/2 and the decreased expression of DUSP6 in ectopic endometrial tissues were significantly suppressed by inhibition of ERK1/2 signaling pathway in ectopic endometrial tissues in experimental mice model. CONCLUSION: In conclusion, TRIM65 promotes invasion of ectopic EMS cells by activating a feedback loop with the ERK1/2/C-myc signaling pathway and may be a potential therapeutic target for EM.

SALL4 promotes tumor progression in breast cancer by targeting EMT.

Sal-like protein 4 (SALL4) is overexpressed in breast cancer and might contribute to breast cancer progression, but the molecular mechanism remains unknown. Here, we found that within a group of 371 ethnic Chinese breast cancer patients, SALL4 was associated with lower grade (P = .002) and progesterone receptor positivity (P = .004) for overall cases; lower Ki67 (P = .045) and high vimentin (P = .007) for luminal cases. Patients with high SALL4 expression in lymph node metastasis showed a significantly worse survival than those with low expression. Knockout of SALL4 in a triple-negative breast cancer cell line MDA-MB-231-Red-FLuc-GFP led to suppressed ability in proliferation, clonogenic formation, migration, and mammosphere formation in vitro, tumorigenicity and lung colonization in vivo. On the other hand, overexpression of SALL4 enhanced migration and mammosphere formation in vitro and tumorigenicity in vivo. Mechanistically, there was a positive correlation between SALL4 expression and mesenchymal markers including Zinc finger E-box binding homeobox 1 (ZEB1), vimentin, Slug, and Snail in vivo. Chromatin immunoprecipitation experiment indicated that SALL4 can bind to the promoter region of vimentin (-778 to -550 bp). Taken together, we hypothesize that SALL4 promotes tumor progression in breast cancer by inducing the mesenchymal markers like vimentin through directly binding to its promoter. Increased SALL4 level in metastatic lymph node relative to the primary site is an important poor survival marker in breast cancer.

Curcumin synergizes with 5-fluorouracil by impairing AMPK/ULK1-dependent autophagy, AKT activity and enhancing apoptosis in colon cancer cells with tumor growth inhibition in xenograft mice.

BACKGROUND: Chemoresistance is a major obstacle that limits the benefits of 5-Fluorouracil (5-Fu)-based chemotherapy for colon cancer patients. Autophagy is an important cellular mechanism underlying chemoresistance. Recent research advances have given new insights into the use of natural bioactive compounds to overcome chemoresistance in colon cancer chemotherapy. As one of the multitargeted and safer phytomedicines, curcumin has been reported to work as cancer-specific chemosensitizer, presumably via induction of autophagic signaling pathways. The precise therapeutic effect of curcumin on autophagy in determining tumorous cells' fate, however, remains unclear. This study was conducted to investigate the differential modulations of the treatments either with 5-Fu alone or 5-Fu combined with curcumin on cellular autophagic responses and viabilities in the human colon cancer cells HCT116 and HT29, and explore molecular signaling transductions underlying the curcumin-mediated autophagic changes and potentiation of 5-Fu's cytotoxicity in vitro and in vivo. METHODS: Cell proliferation assay and morphology observation were used to identify the cytotoxicity of different combinations of curcumin and 5-Fu in HCT116 and HT29 cells. Cell immunofluorescence assay, Flow cytometry and Western blot were employed to detect changes of autophagy and the autophagy-related signaling pathways in the colon cancer cells and/or xenograft mice. RESULTS: Curcumin could significantly augment the cytotoxicity of 5-Fu to the tumorous cells, and the pre-treatment with curcumin followed by 5-Fu (pre-Cur) proved to be the most effective one compared to other two combinations. The chemosensitizing role of curcumin might attribute to the autophagy turnover from being activated in 5-Fu mono-treatment to being inhibited in the pre-Cur treatment as indicated by the changes in expression of beclin-1, p62 and LC3II/LC3I and the intensity of Cyto-ID Green staining. The autophagic alterations appeared to be contributed by down-regulation of not only the phospho-Akt and phospho-mTOR expressions but the phospho-AMPK and phospho-ULK1 levels as well. The cellular activation of AMPK by addition of A-769662 to the pre-Cur combination resulted in reversed changes in expressions of the autophagy protein markers and apoptotic status compared to those of the pre-Cur combination treatment. The findings were validated in the xenograft mice, in which the tumor growth was significantly suppressed in the mice with 25-day combination treatment, and meanwhile expressions of the autophagy markers, P-AMPK and P-ULK1 were all reversely altered in line with those observed in HCT116 cells. CONCLUSION: Pre-treatment with curcumin followed by 5-Fu may mediate autophagy turnover both in vitro and in vivo via AMPK/ULK1-dependent autophagy inhibition and AKT modulation, which may account for the increased susceptibility of the colon cancer cells/xenograft to the cytotoxicity of 5-Fu.