Mechanisms of drug resistance in colon cancer and its therapeutic strategies

Drug resistance develops in nearly all patients with colon cancer, leading to a decrease in the therapeutic efficacies of anticancer agents. This review provides an up-to-date summary on over-expression of ATP-binding cassette (ABC) transporters and evasion of apoptosis, two representatives of transport-based and non-transport-based mechanisms of drug resistance, as well as their therapeutic strategies. Different ABC transporters were found to be up-regulated in colon cancer, which can facilitate the efflux of anticancer drugs out of cancer cells and decrease their therapeutic effects. Inhibition of ABC transporters by suppressing their protein expressions or co-administration of modulators has been proven as an effective approach to sensitize drug-resistant cancer cells to anticancer drugs in vitro. On the other hand, evasion of apoptosis observed in drug-resistant cancers also results in drug resistance to anticancer agents, especially to apoptosis inducers. Restoration of apoptotic signals by BH3 mimetics or epidermal growth factor receptor inhibitors and inhibition of cancer cell growth by alternative cell death pathways, such as autophagy, are effective means to treat such resistant cancer types. Given that the drug resistance mechanisms are different among colon cancer patients and may change even in a single patient at different stages, personalized and specific combination therapy is proposed to be more effective and safer for the reversal of drug resistance in clinics.

Herb-Drug Interactions of Commonly Used Chinese Medicinal Herbs

With more and more popular use of traditional herbal medicines, in particular Chinese herbal medicines, herb-drug interactions have become a more and more important safety issue in the clinical applications of the conventional drugs. Researches in this area are increasing very rapidly. Herb-drug interactions are complicated due to the fact that multiple chemical components are involved, and these compounds may possess diverse pharmacological activities. Interactions can be in both pharmacokinetics and pharmacodynamics. Abundant studies focused on pharmacokinetic interactions of herbs and drugs. Herbs may affect the behavior of the concomitantly used drugs by changing their absorption, distribution, metabolism, and excretion. Studies on pharmacodynamics interactions of herbs and drugs are still very limited. Herb-drug interactions are potentially causing changes in drug levels and drug activities and leading to either therapeutic failure or toxicities. Sometime it can be fatal. The exposures to drugs, lacking of knowledge in the potential adverse herb-drug interactions, will put big risk to patients' safety in medical services. On the contrary, some interactions may be therapeutically beneficial. It may be used to help develop new therapeutic strategies in the future. This chapter is trying to review the development in the area of herb-drug interactions based on the recently published research findings. Information on the potential interactions among the commonly used Chinese medicinal herbs and conventional drugs is summarized in this chapter.

The anti-hepatic fibrosis effects of dihydrotanshinone I are mediated by disrupting the yes-associated protein and transcriptional enhancer factor D2 complex and stimulating autophagy

BACKGROUND AND PURPOSE

Dihydrotanshinone I (DHI), a lipophilic component of traditional Chinese medicine Salvia miltiorrhiza Bunge, has various therapeutic effects. We investigated the anti-fibrotic effect of DHI and its underlying mechanisms in vitro and in vivo.

EXPERIMENTAL APPROACH

Rats subjected to bile duct ligation (BDL) were treated with DHI (25 mg·kg^-1 ·day^-1 , i.p.) for 14 days. Serum biochemical and liver tissue morphological analyses were performed. The human hepatic stellate cell line LX-2 served as a liver fibrosis model in vitro. Liver fibrogenic genes, yes-associated protein (YAP) downstream genes and autophagy markers were examined using western blot and real-time PCR analyses. Similar analyses were done in rat primary hepatic stellate cells (pHSCs). Autophagy flux was assessed by immunofluorescence.

KEY RESULTS

In BDL rats, DHI administration attenuated liver necrosis, bile duct proliferation and collagen accumulation and reduced the expression of genes associated with fibrogenesis, including Tgfb1, Mmp-2, Acta2 and Col1a1. DHI (1, 5, 10 μmol·L^-1 ) time- and dose-dependently suppressed the protein level of COL1A1, TGFβ1 and α-SMA in LX-2 cells and rat pHSCs. Furthermore, DHI blocked the nuclear translocation of YAP, which inhibited the YAP/TEAD2 interaction and its downstream fibrogenic genes, connective tissue growth factor, SOX4 and survivin. This stimulated autophagic flux and accelerated the degradation of liver collagen.

CONCLUSIONS AND IMPLICATIONS

DHI exerts anti-fibrotic effects in BDL rats, LX-2 cells and rat pHSCs by inhibiting the YAP and TEAD2 complex and stimulating autophagy. These findings indicate that DHI may be a potential therapeutic for the treatment of liver fibrosis.

Diterpenes and Their Derivatives as Potential Anticancer Agents

As therapeutic tools, diterpenes and their derivatives have gained much attention of the medicinal scientists nowadays. It is due to their pledging and important biological activities. This review congregates the anticancer diterpenes. For this, a search was made with selected keywords in PubMed, Science Direct, Web of Science, Scopus, The American Chemical Society and miscellaneous databases from January 2012 to January 2017 for the published articles. A total 28, 789 published articles were seen. Among them, 240 were included in this study. More than 250 important anticancer diterpenes and their derivatives were seen in the databases, acting in the different pathways. Some of them are already under clinical trials, while others are in the nonclinical and/or pre-clinical trials. In conclusion, diterpenes may be one of the lead molecules in the treatment of cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Autophagy in 5-Fluorouracil Therapy in Gastrointestinal Cancer: Trends and Challenges

Objective:

5-Fluorouracil (5-FU)-based combination therapies are standard treatments for gastrointestinal cancer, where the modulation of autophagy is becoming increasingly important in offering effective treatment for patients in clinical practice. This review focuses on the role of autophagy in 5-FU-induced tumor suppression and cancer therapy in the digestive system.

Data Sources:

All articles published in English from 1996 to date those assess the synergistic effect of autophagy and 5-FU in gastrointestinal cancer therapy were identified through a systematic online search by use of PubMed. The search terms were “autophagy” and “5-FU” and (“colorectal cancer” or “hepatocellular carcinoma” or “pancreatic adenocarcinoma” or “esophageal cancer” or “gallbladder carcinoma” or “gastric cancer”).

Study Selection:

Critical reviews on relevant aspects and original articles reporting in vitro and/or in vivo results regarding the efficiency of autophagy and 5-FU in gastrointestinal cancer therapy were reviewed, analyzed, and summarized. The exclusion criteria for the articles were as follows: (1) new materials (e.g., nanomaterial)-induced autophagy; (2) clinical and experimental studies on diagnostic and/or prognostic biomarkers in digestive system cancers; and (3) immunogenic cell death for anticancer chemotherapy.

Results:

Most cell and animal experiments showed inhibition of autophagy by either pharmacological approaches or via genetic silencing of autophagy regulatory gene, resulting in a promotion of 5-FU-induced cancer cells death. Meanwhile, autophagy also plays a pro-death role and may mediate cell death in certain cancer cells where apoptosis is defective or difficult to induce. The dual role of autophagy complicates the use of autophagy inhibitor or inducer in cancer chemotherapy and generates inconsistency to an extent in clinic trials.

Conclusion:

Autophagy might be a therapeutic target that sensitizes the 5-FU treatment in gastrointestinal cancer.

Natural Compounds As Modulators of Non-apoptotic Cell Death in Cancer Cells

Cell death is an innate capability of cells to be removed from microenvironment, if and when they are damaged by multiple stresses. Cell death is often regulated by multiple molecular pathways and mechanism, including apoptosis, autophagy, and necroptosis. The molecular network underlying these processes is often intertwined and one pathway can dynamically shift to another one acquiring certain protein components, in particular upon treatment with various drugs. The strategy to treat human cancer ultimately relies on the ability of anticancer therapeutics to induce tumor-specific cell death, while leaving normal adjacent cells undamaged. However, tumor cells often develop the resistance to the drug-induced cell death, thus representing a great challenge for the anticancer approaches. Numerous compounds originated from the natural sources and biopharmaceutical industries are applied today in clinics showing advantageous results. However, some exhibit serious toxic side effects. Thus, novel effective therapeutic approaches in treating cancers are continued to be developed. Natural compounds with anticancer activity have gained a great interest among researchers and clinicians alike since they have shown more favorable safety and efficacy then the synthetic marketed drugs. Numerous studies in vitro and in vivo have found that several natural compounds display promising anticancer potentials. This review underlines certain information regarding the role of natural compounds from plants, microorganisms and sea life forms, which are able to induce non-apoptotic cell death in tumor cells, namely autophagy and necroptosis.

Inflammation by Breast Implants and Adenocarcinoma: Not Always a Bad Company

BACKGROUND

Inflammation and tumor are now an inseparable binomial. Inflammation may also derive by the use of breast implants followed by the formation of a periprosthetic capsule. It is known that tumor cells, in an inflamed microenvironment, can profit by the paracrine effect exerted also by mesenchymal stem cells (MSCs). Here we evaluated the role of inflammation on the immunobiology of MSCs before and after cocultures with cells derived from breast adenocarcinoma.

METHODS

MSCs derived from both inflamed (I-MSCs) and control (C-MSCs) tissues were isolated and cocultured with MCF7 cells derived from breast adenocarcinoma. Before and after cocultures, the proliferation rate of MCF7 cells and the expression/secretion of cytokines related to inflammation were tested.

RESULTS

Before cocultures, higher levels of cytokine related to chronic inflammation were detected in I-MSCs than in C-MSCs. After cocultures with MCF7, C- and I-MSCs show a variation in cytokine production. In detail, IL-2, IL-4, IL-5, IL-10, IL-13, TGF-β and G-CSF were decreased, whereas IL-6, IL-12, IFN-γ, and IL-17 were oversecreted. Proliferation of MCF7 was significantly increased after cocultures with I-MSCs.

CONCLUSIONS

Inflammation at the site of origin of MSCs affects their immunobiology. Even if tumor cells increased their proliferation rate after cocultures with I-MSCs, the analysis of the cytokines, known to play a role in the interference of tumor cells with the host immune system, absolves completely the breast implants from the insult to enforce the risk of adenocarcinoma.

Chinese Herbal Medicine and Fluorouracil-Based Chemotherapy for Colorectal Cancer: A Quality-Adjusted Meta-Analysis of Randomized Controlled Trials

Background Chinese herbal medicines reportedly increase efficacy and minimize toxicity of chemotherapy; however, little attention has been paid to how poor study quality can bias outcomes. Methods We systematically searched MEDLINE, TCMLARS, EMBASE, and Cochrane Library for randomized controlled trials of Chinese herbal medicines combined with fluorouracil-based chemotherapy compared with the same chemotherapy alone. We screened for eligibility, extracted data, and pooled data with random-effects meta-analysis. Outcome measures were survival, toxicity, tumor response, performance status, quality of life, and Cochrane Risk of Bias (ROB) criteria to critically evaluate the quality of reporting in the randomized trials included in the meta-analysis. Results We found 36 potentially eligible studies, with only 3 (those with low ROB) qualifying for meta-analysis. Two reported chemotherapy-related diarrhea reduced by 57% (relative risk [RR] = 0.43; 95% CI = 0.19-1.01; I(2) test for variation in RR due to heterogeneity = 0.0%), with nonsignificant results. Two reported white blood cell toxicity reduced by 66% (RR = 0.34; 95% CI = 0.16-0.72; I(2) test for variation in RR due to heterogeneity = 0.0%), with statistically significant results. Stratifying analysis by studies with high versus low ROB, we found substantial overestimation of benefit: Studies with high ROB overestimated by nearly 2-fold reduction of platelet toxicity by Chinese herbal medicines (RR = 0.35, 95% CI = 0.15-0.84 vs RR = 0.65, 95% CI = 0.11-3.92). Studies with high ROB overestimated by nearly 2-fold reduction of vomiting toxicity (RR = 0.45, 95% CI = 0.33-0.61 vs RR = 0.87, 95% CI = 0.48-1.58). And, studies with high ROB overestimated by 21% the reduction in diarrhea toxicity (RR = 0.34, 95% CI = 0.20-0.58 vs RR = 0.43, 95% CI = 0.19-1.01). Studies with high ROB also overestimated by 16% improvement in tumor response (RR = 1.39, 95% CI = 1.18-1.63 vs RR = 1.20; 95% CI = 0.81-1.79). Not accounting for ROB would have exaggerated evidence of benefit and failed to detect nonsignificance of results. Conclusions In the present analysis, involving 36 studies, 2593 patients, 20 outcomes, 36 medical institutions, and 271 named research authors, 92% of the data points were from studies at high ROB. Given the poor quality of the data in studies identified, it cannot be concluded whether combining Chinese herbs with chemotherapy reduces toxicity of chemotherapy.

Mechanisms of drug resistance in colon cancer and its therapeutic strategies

Drug resistance develops in nearly all patients with colon cancer, leading to a decrease in the therapeutic efficacies of anticancer agents. This review provides an up-to-date summary on over-expression of ATP-binding cassette (ABC) transporters and evasion of apoptosis, two representatives of transport-based and non-transport-based mechanisms of drug resistance, as well as their therapeutic strategies. Different ABC transporters were found to be up-regulated in colon cancer, which can facilitate the efflux of anticancer drugs out of cancer cells and decrease their therapeutic effects. Inhibition of ABC transporters by suppressing their protein expressions or co-administration of modulators has been proven as an effective approach to sensitize drug-resistant cancer cells to anticancer drugs in vitro. On the other hand, evasion of apoptosis observed in drug-resistant cancers also results in drug resistance to anticancer agents, especially to apoptosis inducers. Restoration of apoptotic signals by BH3 mimetics or epidermal growth factor receptor inhibitors and inhibition of cancer cell growth by alternative cell death pathways, such as autophagy, are effective means to treat such resistant cancer types. Given that the drug resistance mechanisms are different among colon cancer patients and may change even in a single patient at different stages, personalized and specific combination therapy is proposed to be more effective and safer for the reversal of drug resistance in clinics.

Bevacizumab reduced auto-phosphorylation of VEGFR2 to protect HDM-induced asthma mice

Vascular endothelial growth factor (VEFG) is a major angiogenic factor involved in both normal physiological processes, such as embryonic development and wound healing, and in diseases, like cancer. Recent studies have revealed the functions of VEGF in inflammation and immunoregulation. Asthma is a chronic inflammation of the airways characterized by airway epithelial barrier dysfunction and imbalance in T-helper (Th) 1/Th2 during immunoregulation. We hypothesized that VEGF plays an important role in asthma. Utilizing a house dust mite extract (HDM)-induced murine model of asthma, we investigated whether bevacizumab, a humanized anti-VEGF monoclonal antibody, could protect the epithelial barrier in murine airways. We found that bevacizumab reduced airway hyper-responsiveness (AHR) and airway inflammation induced by HDM. In addition, HDM exposure promoted expression of VEGF, and caused AHR, disruptions of the epithelial barrier, and airway inflammation. Bevacizumab ameliorated AHR and the release of Th2 cytokines, thereby protecting the epithelial barrier. Our data suggest that bevacizumab may be a new therapeutic strategy for asthma.

Interaction effects on cytochrome P450 both in vitro and in vivo studies by two major bioactive xanthones from Halenia elliptica D. Don

The major components, 1-hydroxy-2,3,5-trimethoxy-xanthone (HM-1) and 1,5-dihydroxy-2,3-dimethoxy-xanthone (HM-5) isolated from Halenia elliptica D. Don (Gentianaceae), could cause vasodilatation in rat coronary artery with different mechanisms. In this work, high-performance liquid chromatography coupled to ion trap time-of-flight mass spectrometry (LCMS-IT-TOF) was used to clarify the metabolic pathways, and CYP450 isoform involvement of HM-1 and HM-5 were also studied in rat. At the same time, in vivo inhibition effects of HM-1 and ethyl acetate extracts from origin herb were studied. Three metabolites of HM-5 were found in rat liver microsomes (RLMs); demethylation and hydroxylation were the major phase I metabolic reactions for HM-5. Multiple CYP450s were involved in metabolism of HM-1 and HM-5. The inhibition study showed that HM-5 inhibited Cyp1a2, 2c6 and 2d2 in RLMs. HM-1 inhibited activities of Cyp1a2, Cyp2c6 and Cyp3a2. In vivo experiment demonstrated that both HM-1 and ethyl acetate extracts could inhibit Cyp3a2 in rats. In conclusion, the metabolism of xanthones from the origin herb involved multiple CYP450 isoforms; in vitro, metabolism of HM-5 was similar to that of its parent drug HM-1, but their inhibition effects upon CYP450s were different; in vivo, Cyp3a2 could be inhibited by HM-1 and ethyl acetate extracts.

Silver nanoparticles defeat p53-positive and p53-negative osteosarcoma cells by triggering mitochondrial stress and apoptosis

Loss of function of the tumour suppressor p53 observed frequently in human cancers challenges the drug-induced apoptotic elimination of cancer cells from the body. This phenomenon is a major concern and provides much of the impetus for current attempts to develop a new generation of anticancer drugs capable of provoking apoptosis in a p53-independent manner. Since silver nanoparticles (AgNPs) possess unique cytotoxic features, we examined, whether their activity could be exploited to kill tumour suppressor-deficient cancer cells. Therefore, we investigated the effects of AgNPs on osteosarcoma cells of different p53 genetic backgrounds. As particle diameters might influence the molecular mechanisms leading to AgNP-induced cell death we applied 5 nm and 35 nm sized citrate-coated AgNPs. We found that both sized AgNPs targeted mitochondria and induced apoptosis in wild-type p53-containing U2Os and p53-deficient Saos-2 cells. According to our findings AgNPs are able to kill osteosarcoma cells independently from their actual p53 status and induce p53-independent cancer cell apoptosis. This feature renders AgNPs attractive candidates for novel chemotherapeutic approaches.

Isocryptotanshinone, a STAT3 inhibitor, induces apoptosis and pro-death autophagy in A549 lung cancer cells

Signal transducer and activator of transcription 3 (STAT3) is a potential drug target for chemotherapy. Cryptotanshinone (CTS) was identified as a potent STAT3 inhibitor, while the effect of other tanshinones remains unknown. In this study, the influence of eight tanshinones on STAT3 activity was initially screened and isocryptotanshinone (ICTS) significantly inhibited STAT3 activity in a dual luciferase assay. ICTS inhibited the constitutive and inducible phosphorylation of STAT3 at Y705 without affecting the phosphorylation of STAT3 at S727 in A549 lung cancer cells. Furthermore, ICTS inhibited the nuclear translocation of STAT3. Compared with CTS, ICTS exhibited a stronger inhibitory effect on STAT3 phosphorylation and on A549 cytotoxicity. ICTS induced autophagy as evidenced by the accumulation of autophagic vacuoles and the increased expression of LC3 protein and autophagosomes. ICTS-induced cell death was partially reversed by the autophagy inhibitor chloroquine. The docking assay predicted that both ICTS and CTS bind the SH2 domain of STAT3. ICTS formed hydrogen bonds and pi-pi interaction with the nearby amino acid residues of Lys591, Arg609, and Ser636. These findings suggested that ICTS, a natural compound, is a potent STAT3 inhibitor. ICTS induced apoptosis and pro-death autophagy in A549 cells.

MSCs and inflammation: new insights into the potential association between ALCL and breast implants

Possible association between anaplastic large cell lymphoma (ALCL) and breast implants has been suggested. In this context, formation of the periprosthetic capsule has been reported as a cause of inflammation, which plays a key role in tumor onset. Tumors take advantage of inflammation to influence and interfere with the host immune response by secreting multiple factors, and their onset and survival is in turn affected by the paracrine effects from mesenchymal stem cells (MSCs). In this study, we tried to clarify how inflammation can modify the immunobiology and the exerted paracrine effect of MSCs. MSCs derived from both inflamed (I-MSCs) and control (C-MSCs) tissues were isolated and co-cultured with an ALCL cell line. Proliferation rate and the expression of selected cytokines were tested. I-MSCs secrete higher levels of cytokine related to chronic inflammation than C-MSCs. After co-cultures with KI-JK cells, C- and I-MSCs show the same variation in the cytokine expression, with an increase of IL2, IL4, IL5, IL10, IL13, TNF-α, TGF-β, and G-CSF. Proliferation of ALCL cells was not influenced by co-cultures. Our results state that (i) inflamed microenvironment affects the immunobiology of MSCs modifying the profile of the expressed cytokines, and (ii) the paracrine effects exerted by MSCs on ALCL cells are not influenced by inflammation. Moreover, it seems that ALCL cells are able to manipulate MSCs' immunoregulatory properties to evade the host immune control. Nevertheless, this ability is not associated with inflammation and the question about BIA-ALCL is not proved by our experiments.