Resveratrol restrains colorectal cancer metastasis by regulating miR-125b-5p/TRAF6 signaling axis.

Colorectal cancer is one of the most common malignancies with a high incidence, metastatic tendency and low 5-year survival rate. Resveratrol, a polyphenolic compound has been shown to inhibit colorectal cancer metastasis in recent studies. Its underlying molecular mechanism remains to be elucidated. Our findings demonstrated that miR-125b-5p, acting as a tumor suppressor, was conspicuously down-regulated in both colorectal cancer tissues and cell lines. The expression of miR-125b-5p negatively correlated with the expression of its direct target TNF receptor associated factor 6 (TRAF6). Both miR-125b-5p overexpression and TRAF6 knockdown inhibited metastasis of colorectal cancer cells. In addition, we uncovered that resveratrol up-regulated miR-125b-5p by increasing its stability and suppressed TRAF6-induced signal pathway in a dose/time-dependent manner. Resveratrol could significantly curtail the migration and invasion of colorectal cancer cells, which was counteracted by miR-125b-5p knockdown or TRAF6 overexpression. These results indicated that resveratrol could restrain colorectal cancer metastasis by promoting miR-125b-5p/TRAF6 signaling axis. Furthermore, lung metastasis models of colorectal cancer were constructed by tail vein injection. Down-regulation of miR-125b-5p could facilitate colorectal cancer metastasis in vivo, which could be impeded by resveratrol. In conclusion, our findings delineated the miR-125b-5p/TRAF6 signaling axis as a novel molecular mechanism underlying the metastatic process in colorectal cancer, as well as a prospective therapeutic target. Resveratrol disrupts colorectal cancer metastasis by activating miR-125b-5p/TRAF6 signal pathway and might improve the clinical outcome of colorectal cancer patients with low expression of miR-125b-5p.

DBF4 Dependent Kinase Inhibition Suppresses Hepatocellular Carcinoma Progression and Potentiates Anti-Programmed Cell Death-1 Therapy.

The progression of hepatocellular carcinoma (HCC) remains a huge clinical challenge, and elucidation of the underlying molecular mechanisms is critical to develop effective therapeutic strategy. Dumbbell former 4 (DBF4) complexes with cell division cycle 7 (CDC7) to form DBF4-dependent kinase (DDK), playing instrumental roles in tumor cell survival, whereas its roles in HCC remain elusive. This study revealed that DBF4 expression was upregulated in HCC and constituted an independent prognostic factor of patient survival. We identified p65 as an upstream inducer which increased DBF4 expression by directly binding to its promoter. DBF4 accelerated HCC cell proliferation and tumorigenesis in vitro and in vivo. Mechanistically, DBF4 complexed with CDC7 to bind to the coiled coil domain of STAT3 and activate STAT3 signaling through XPO1-mediated nuclear exportation. Notably, p65 enhanced the nuclear transport of DDK and DDK-STAT3 interaction by transcriptionally upregulating XPO1. DBF4 expression positively correlated with activated STAT3 and XPO1 in HCC tissues. Furthermore, combining DDK inhibitor XL413 with anti-PD-1 immunotherapy dramatically suppressed HCC growth and prolonged the survival of HCC-bearing mouse. Our findings reveal that DDK activates STAT3 pathway and facilitates HCC progression, and demonstrate the proof of the concept of targeting DDK to improve the efficacy of HCC immunotherapy.

Study of the mining and aquifer interactions in complex geological conditions and its management.

The interaction of mining and the surface water or aquifer system in varying overburden strata conditions is one of the most critical aspects of sustainable mining practices, that can lead to water loss or water inrush into openings. This paper examined this phenomenon in a complex strata condition via a case study, and proposed a new mining design to minimize the impact of longwall mining on the overlaying aquifer. A range of factors have been identified contributing to the potential disturbance of the aquifer, including the extent of the water-rich area, the characteristics of overburden rock units, and the development height of the water-conducting fracture zone. In this study, the transient electromagnetic method and the high-density three-dimensional electrical method were used to identify two areas prone to water inrush danger in the working face. The vertical range of the water-rich abnormal area 1 is 45-60 m away from the roof, with an area of 3334 m2. The vertical range of the water-rich abnormal area 2 is 30-60 m away from the roof, with an area of approximately 2913 m2. The bedrock drilling method was used to determine that the thinnest part of the bedrock, with a thickness of approximately 60 m, and the thickest part, with a thickness of approximately 180 m. The maximum mining-induced height of the fracture zone was 42.64 m using empirical method, theoretical prediction based on the rock stratum group, field monitoring. In summary, the high risk area was determined, and the analysis shows that the size of the water prevention) pillar was 52.6 m, which was smaller than the safe water prevention pillar actually set in the mining range. The research conclusion provides important safety guidance significance for the mining of similar mines.

Pralatrexate mediates effective killing of gemcitabine-resistant pancreatic cancer: role of mTOR/4E-BP1 signal pathway.

Gemcitabine is the first-line chemotherapeutic agent for pancreatic cancer. However, gemcitabine-resistance frequently leads to poor prognosis. Exploring new chemotherapeutic agents is important for patients with gemcitabine-resistant pancreatic cancer. In this study, we established a new acquired gemcitabine-resistant pancreatic cancer cell line BxPC-GEM-20 from parental BxPC-3. We found that pralatrexate significantly inhibited the growth of BxPC-GEM-20. The half-maximal inhibitory concentration of pralatrexate on BxPC-GEM-20 cell was about 3.43 ± 0.25 nM. Pralatrexate was found to effectively inhibit the clonal growth of BxPC-GEM-20 cell. Additionally, pralatrexate at 20 mg/kg had an excellent tumor inhibitory effect with an inhibitory rate of 76.92% in vivo. This pralatrexate therapy showed good safety profile that with little to no additional influence on the hepatic, renal function as well as body weight changes in nude mice. Pralatrexate was confirmed to prevent cells from entering the G2/M phase, leading to the promotion of apoptosis and autophagy. Further analysis demonstrated that the reduced phosphorylation of mTOR played a significant role in the tumor cell damage caused by pralatrexate. Pralatrexate effectively inhibited the mTOR/4E-BP1 pathway. Activation of mTOR pathway can further obstruct the repressive effect of pralatrexate on gemcitabine-resistant pancreatic cancer. In summary, pralatrexate induces effective inhibition of gemcitabine-resistant pancreatic cancer. This may lead to the expansion of pralatrexate's application and offer benefit to gemcitabine-resistant pancreatic cancer patients in the future.

The contributions of extrachromosomal DNA elements in neoplasm progression.

Extrachromosomal DNA (ecDNA) is a small, circular structure of DNA found outside chromosomes, in the cytoplasm and outside cells. Since the discovery of ecDNA in 1964, more studies have verified the significant prospect and application potential of its use in oncology. The presence of ecDNA is associated with a series of tumor activities such as the increasing or decreasing of oncogene copies, carcinogenic transmission, and activation of related signaling pathways. This review focuses on discussing the structure of ecDNA and its relevance in carcinogenesis, angiogenesis, drug resistance and metastasis.

AG-1024 Sensitizes Sorafenib-Resistant Hepatocellular Carcinoma Cells to Sorafenib via Enhancing G1/S Arrest.

PURPOSE: The frequency in resistance to sorafenib accounts for the grim prognosis of advanced hepatocellular carcinoma (HCC). In the present study, we explore the anti-cancer efficacy of co-administration of sub-toxic AG-1024 with sorafenib in HCC cells to enhance the sensitivity of these cells to sorafenib. MATERIALS AND METHODS: Two acquired sorafenib-resistant HCC cells, SNU-sora-5 and SK-sora-5, were established and verified. The MTT assay, colony formation assay, cell morphology detection and flow cytometric analysis were then used to determine the anti-tumor effects of the co-administration of sub-toxic AG-1024 and sorafenib. Finally, the potential molecular mechanism was preliminarily examined. RESULTS: Compared to parental cell lines, the acquired sorafenib-resistant cell lines, SNU-sora-5 and SK-sora-5, were more resistant to sorafenib. Sub-toxic AG-1024 markedly enhanced sorafenib-mediated cell inhibition in acquired sorafenib-resistant HCC strains, with a reversal index (RI) of 4.64 in SNU-sora-5 and 4.58 in SK-sora-5 cell lines. Moreover, co-administration of sub-toxic AG-1024 and sorafenib exerted dramatic cytotoxicity compared with sorafenib alone in the intrinsic sorafenib-resistant HCC-LM3 cells. In contrast to high-dose sorafenib, sub-toxic AG-1024 combined with sorafenib had less impact on apoptosis while significantly enhancing G1/S arrest via activation of the mTOR/p21 signaling pathway. The more, pharmacological inhibition of mTOR activity by inhibitor Palomid 529 significantly antagonized the synergistic anti-cancer effects of AG-1024 and sorafenib in HCC cells. CONCLUSION: The current findings indicate that sub-toxic AG-1024 may be a promising therapeutic agent in enhancing the sensitivity in HCC cells to sorafenib, bringing hope to HCC patients refractory to sorafenib treatment.

Endoplasmic reticulum stress triggers delanzomib-induced apoptosis in HCC cells through the PERK/eIF2α/ATF4/CHOP pathway.

For limited clinical benefits and acquired resistance by sorafenib, new therapeutic strategies and molecular targets for the treatment of advanced hepatocellular carcinoma (HCC) are urgently needed. This study aimed to evaluate the potential antitumor effects of the second-generation proteasome inhibitor delanzomib on HCC. The results demonstrated that delanzomib displayed excellent antitumor activity on HCC cells with sensitivity or resistance to sorafenib in a time- and dose-response manner, by inducing G2/M cell cycle arrest and apoptosis in vitro. Cell cycle arrest was associated with the activation of p21/Cdc2/cyclin B1 pathway, and cell apoptosis was confirmed by PARP and caspase-3 cleavage. In addition, delanzomib induced endoplasmic reticulum stress (ERS) in HCC cells by activating the PERK and ERS-associated proteins including p-eIF2α, ATF4 and CHOP. Selective inhibition of eIF2α dephosphorylation by salubrinal could significantly reduce delanzomib-induced apoptosis in HCC cells. In vivo, delanzomib could also exhibit effective antitumor properties on patient-derived xenograft mouse model of HCC with relative low drug-associated cytotoxicity. Compared to control group, 3 and 10 mg/kg of delanzomib significantly reduced the tumor volume by 33.1% and 87.2% respectively after 3 weeks treatment, with no significant change on the body weight and the level of serum biochemical indexes including ALT, AST and BUN. In conclusion, delanzomib could exhibit good pre-clinical antitumor effects against HCC cells by inducing ERS and activating the PERK/eIF2α/ATF4/CHOP pathway, as potential drug candidate on treatment of advanced HCC patients.

Y-320, a novel immune-modulator, sensitizes multidrug-resistant tumors to chemotherapy.

Y-320, a novel immune-modulator, inhibits IL-17 production by CD4+ T cells stimulated with IL-15. Its use in autoimmune diseases such as rheumatoid arthritis has been documented. However, no studies have be conducted to evaluate its application in cancer treatment either as mono or combined therapy. This study demonstrated that while Y-320 had little effect on multidrug resistance (MDR) cell lines, it induced remarkable injury to MDR tumor cells when concurrently administered with other chemotherapeutic agents. Concomitant use of Y-320 with a low dose of paclitaxel significantly sensitized MDR tumors by inducing G2/M phase arrest and apoptosis. Further analyses indicated that Y-320 was a substrate of P-glycoprotein (P-gp). It could inhibit P-gp efflux function without altering P-gp expression, and subsequently reverse P-gp mediated drug resistance in MDR cells. The co-administration of Y-320 and paclitaxel suppressed tumor growth remarkably with an inhibition rate of 77.1% compared to 6.5% in the paclitaxel monotherapy group in vivo. This co-treatment did not increase extra complications in MDR tumor xenograft models. Particularly, no significant changes in body weight and hepatorenal serology were observed with the co-treatment. In conclusion, our results confirm that Y-320 is a promising chemotherapy sensitizer for the first time. The co-administration of Y-320 and chemotherapeutic agents might be an effective and low-toxicity chemotherapeutic regime for the MDR tumor patients.

NKILA, a prognostic indicator, inhibits tumor metastasis by suppressing NF-κB/Slug mediated epithelial-mesenchymal transition in hepatocellular carcinoma.

The metastasis of hepatocellular carcinoma (HCC) is one of the major obstacles hindering its therapeutic efficacy, leading to low surgical resection rate, high mortality and poor prognosis. Accumulating evidence has shown that both long noncoding RNA (lncRNA) and NF-κB play vital roles in the regulation of cancer metastasis. However, the clinical significance and biological function of NKILA (NF-κB interacting lncRNA) and its interaction with NF-κB in HCC remain unknown. In this study, we demonstrated that NKILA was down-regulated in HCC tissues and cell lines, and decreased NKILA expression was significantly associated with larger tumor size and positive vascular invasion in HCC patients. NKILA reduction was an independent risk factor of HCC patients' poor prognosis, and the 5-year overall survival (OS) rates of patients with low and high NKILA expression were 15.6% and 60.0%, respectively. Moreover, NKILA inhibits migration and invasion of HCC cells both in vitro and in vivo. Mechanistically, NKILA prevents Slug/epithelial to mesenchymal transition (EMT) pathway via suppressing phosphorylation of IκBα, p65 nuclear translocation and NF-κB activation. In conclusion, these results indicate that NKILA might serve as an effective prognostic biomarker and a promising therapeutic target against HCC metastasis.

LY2228820 induces synergistic anti-cancer effects with anti-microtubule chemotherapeutic agents independent of P-glycoprotein in multidrug resistant cancer cells.

Side-effects and resistance substantially limit the efficacy of chemotherapy. One possible solution to this persistent problem would be co-administration of targeted therapy and chemotherapy to achieve synergistic anti-cancer effects without extra toxicity. Here, we reported that LY2228820, a selective inhibitor of p38-MAPK signaling pathway, could induce synergistic anti-cancer effects with anti-microtubule (AMT) chemotherapy both in vitro and in vivo. In drug-resistant cancer cells, treatment with either LY2228820 or AMT drug alone was compatible with viability, while co-administration of both led to dramatic cytotoxicity, G2/M arrest and apoptosis. Moreover, co-treatment with LY2228820 notably improved the effectiveness of paclitaxel without exhibiting adverse effects in vivo. Mechanistic studies showed that LY2228820 sensitized cancer cells to AMT agents independent of P-gp. LY2228820 did not influence either the expression or the function of P-gp. Instead, it could inhibit p38-HSP27 signaling axis by down-regulating p-HSP27. Furthermore, LY2228820 blocked the p-HSP27 mediated protective response against AMT drugs in tumor cells, resulting in mitochondrial instability and the activation of mitochondrial death pathways. This P-gp-independent regime containing LY2228820 and AMT agents could produce synergistic anti-cancer effects without extra systematic toxicity. Our study offers a novel strategy for improving the therapeutic efficacy of AMT drugs by achieving a better balance between efficacy and toxicity. This new combination regime could be advantageous in patients who show little response to the maximal dosage of AMT chemotherapy, as well as those unable to tolerate the systematic toxicity of these agents in clinic.

COL6A1 promotes metastasis and predicts poor prognosis in patients with pancreatic cancer.

Pancreatic cancer is one of the most aggressive cancers worldwide with a high mortality rate. Prognosis remains poor even in this era of advanced medicine mainly due to early metastasis and invasion. The present study aimed to explore and validate predictors of distant metastasis and prognosis in pancreatic cancer. In our preliminary experiment, we established a novel metastatic pancreatic cancer cell line BxPC­M8 from parent BxPC­3 cells. Via whole genome sequencing, RT­qPCR, western blotting, migration and invasion assays, we initially found that BxPC­M8 shared similar biological characteristics to BxPC­3, but only differed in enhanced metastatic and invasive capabilities with a significant increase in collagen type VI α1 chain (COL6A1) expression. Knockdown of COL6A1 via small interfering RNA led to a significant decrease in migration and invasion of BxPC­M8 cells, suggesting suppressed epithelial­mesenchymal transition. Furthermore, a significant increase in COL6A1 expression was observed in cancerous tissue compared with paracancerous tissue (40.7 vs 3.7, P=0.001). Additionally, its expression was observed to be significantly associated with distant metastasis and vascular invasion at the time of surgery. Multivariate analysis revealed that COL6A1 expression (hazard ratio 1.90, 95% confidence interval 1.04­3.47, P=0.037) is an independent predictor of overall survival (OS). The median OS observed for COL6A1+ and COL6A1­ patients was found to be 8±4 and 14±7 months (P=0.021), respectively. Of note, we identified that COL6A1 expression in tissue samples was associated with significantly reduced OS (P=0.001), demonstrating that COL6A1 may serve an important role in the metastatic process and could be considered as a predictor of poor outcomes in patients with pancreatic cancer. In addition, our findings suggest that COL6A1 could be an indicator of distant metastasis and a valid prognostic predictor in such patients; however, further investigation is required.

Identification of potential miRNA-mRNA regulatory network contributing to pathogenesis of HBV-related HCC.

BACKGROUND: Hepatitis B virus (HBV) is one of the major risk factors of hepatocellular carcinoma (HCC). Increasing evidence indicates that microRNA (miRNA)-mRNA axis is involved in HCC. However, a comprehensive miRNA-mRNA regulatory network in HBV-related HCC is still absent. This study aims to identify potential miRNA-mRNA regulatory pathways contributing to pathogenesis of HBV-related HCC. METHODS: Microarray GSE69580 was downloaded from Gene Expression Omnibus (GEO) database. GEO2R and 'R-limma' were used to conduct differential expression analysis. The common miRNAs appeared in the two analytic sets were screened as potential differentially expressed miRNAs (DE-miRNAs). The prognostic roles of screened DE-miRNAs in HCC were further evaluated using Kaplan-Meier plotter database. Target genes of DE-miRNAs were predicted by miRNet. Then, protein-protein interaction (PPI) networks were established for these targets via the STRING database, after which hub genes in the networks were identified by Cytoscape. Functional annotation and pathway enrichment analyses for the target genes were performed through DAVID database. Three enriched pathways related to HBV-related HCC were selected for further analysis and potential target genes commonly appeared in all three pathways were screened. Cytoscape was employed to construct miRNA-hub gene network. The expression and correlation of potential miRNAs and targets were further detected in clinical HBV-related HCC samples by qRT-PCR. RESULTS: 7 upregulated and 9 downregulated DE-miRNAs were accessed. 5 of 7 upregulated DE-miRNAs and 5 of 7 downregulated DE-miRNAs indicated significant prognostic roles in HCC. 2312 and 1175 target genes were predicted for the upregulated and downregulated DE-miRNAs, respectively. TP53 was identified as the hub gene in the PPI networks. Pathway enrichment analysis suggested that these predicted targets were linked to hepatitis B, pathways in cancer, microRNAs in cancer and viral carcinogenesis. Further analysis of these pathways screened 20 and 16 target genes for upregulated and downregulated DE-miRNAs, respectively. By detecting the expression of 36 target genes, six candidate target genes were identified. Finally, a potential miRNA-mRNA regulatory network was established based on the results of qRT-PCR and expression correlation analysis. CONCLUSIONS: In the study, potential miRNA-mRNA regulatory pathways were identified, exploring the underlying pathogenesis and effective therapy strategy of HBV-related HCC.

Identification of invasion-metastasis-associated microRNAs in hepatocellular carcinoma based on bioinformatic analysis and experimental validation.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most lethal cancer, mainly attributing to its high tendency to metastasis. Vascular invasion provides a direct path for solid tumor metastasis. Mounting evidence has demonstrated that microRNAs (miRNAs) are related to human cancer onset and progression including invasion and metastasis. METHODS: In search of invasion-metastasis-associated miRNAs in HCC, microarray dataset GSE67140 was downloaded from the Gene Expression Omnibus database. Differentially expressed miRNAs (DE-miRNAs) were obtained by R software package and the potential target genes were predicted by miRTarBase. The database for annotation, visualization and integrated discovery (DAVID) was introduced to perform functional annotation and pathway enrichment analysis for these potential targets of DE-miRNAs. Protein-protein interaction (PPI) network was established by STRING database and visualized by Cytoscape software. The effects of the miR-494-3p and miR-126-3p on migration and invasion of HCC cell lines were evaluated by conducting wound healing assay and transwell assay. RESULTS: A total of 138 DE-miRNAs were screened out, including 57 upregulated miRNAs and 81 downregulated miRNAs in human HCC tumors with vascular invasion compared with human HCC tumors without vascular invasion. 762 target genes of the top three upregulated and downregulated miRNAs were predicted, and they were involved in HCC-related pathways, such as pathway in cancer, focal adhesion and MAPK signaling pathway. In the PPI network, the top 10 hub nodes with higher degrees were identified as hub genes, such as TP53 and MYC. Through constructing the miRNA-hub gene network, we found that most of hub genes could be potentially modulated by miR-494-3p and miR-126-3p. Of note, miR-494-3p and miR-126-3p was markedly upregulated and downregulated in HCC cell lines and tissues, respectively. In addition, overexpression of miR-494-3p could significantly promote HCC migration and invasion whereas overexpression of miR-126-3p exerted an opposite effect. CONCLUSIONS: Targeting miR-494-3p and miR-126-3p may provide effective and promising approaches to suppress invasion and metastasis of HCC.

Cabazitaxel, a novel chemotherapeutic alternative for drug-resistant hepatocellular carcinoma.

The prognosis of advanced hepatocellular carcinoma (HCC) patients remains extremely poor, partially due to the development of acquired resistance to sorafenib and chemotherapy. Cabazitaxel, a semisynthetic taxane, has been approved for the therapy of docetaxel-resistant prostate cancer. However, no studies have been performed on the effect of cabazitaxel on HCC, and whether cabazitaxel remains sensitive in chemotherapy-resistant and sorafenib-resistant HCC cells is not clear. Our results demonstrate that cabazitaxel is highly toxic to HCC cell lines in a time- and dose-dependent manner by inducing G2/M phase arrest and apoptosis in vitro. Cabazitaxel also significantly suppresses HCC tumor growth in vivo. In chemotherapy-resistant HCC cell Huh-TS-48 with P-gp-overexpression, cabazitaxel shows less cross-resistant to other chemotherapeutic agents. The resistance fold of cabazitaxel, doxorubicin, paclitaxel, docetaxel and vinorelbine is 1.53, 8.60, 38.58, 15.53 and 18.06 respectively. Furthermore, sorafenib-resistant HCC cell SK-sora-5 is still sensitive to cabazitaxel. The IC50 values of cabazitaxel after 72 h exposure for parental cell SK-hep-1 and resistant cell SK-sora-5 are 0.84 and 0.73 nM. The results indicate that cabazitaxel is a potential agent to treat HCC after developing chemotherapy resistance caused by overexpression of P-gp and acquired resistance to sorafenib, and might improve prognosis in advanced HCC patients.

A miR-20a/MAPK1/c-Myc regulatory feedback loop regulates breast carcinogenesis and chemoresistance.

Chemoresistance often leads to the failure of breast cancer treatment. MicroRNAs (miRNAs) play an important role in the progression and chemoresistance of cancer. However, because of the complexity of the mechanisms of chemoresistance and the specificity of miRNA regulation in different cell types, the function of miR-20a in breast cancer chemoresistance is still unclear. Here, by using miRNA microarray and high-content screening techniques, we found that miR-20a/b were significantly downregulated in breast cancer tissues compared with normal breast tissues, and low miR-20a/b expression was correlated with poor survival in breast cancer patients. Ectopic overexpression of miR-20a sensitized breast cancer cells to a broad spectrum of chemotherapy drugs and suppress their proliferation both in vitro and in vivo. Further study demonstrated that miR-20a directly targeted the 3'untranslated region of MAPK1, and thus downregulated the expression of P-gp and c-Myc by inhibiting the MAPK/ERK signaling pathway, whereas c-Myc can bind to the promoter region of the miR-20a gene to promote the expression of miR-20a. Together, our study identified a novel miR-20a/MAPK1/c-Myc feedback loop that regulates breast cancer growth and chemoresistance. These findings suggest that miR-20a synergizing with anticancer drugs will be a promising treatment strategy, especially for chemoresistant patients.

New Generation Nanomedicines Constructed from Self-Assembling Small-Molecule Prodrugs Alleviate Cancer Drug Toxicity.

The therapeutic index for chemotherapeutic drugs is determined in part by systemic toxicity, so strategies for dose intensification to improve efficacy must also address tolerability. In addressing this issue, we have investigated a novel combinatorial strategy of reconstructing a drug molecule and using sequential drug-induced nanoassembly to fabricate supramolecular nanomedicines (SNM). Using cabazitaxel as a target agent, we established that individual synthetic prodrugs tethered with polyunsaturated fatty acids were capable of recapitulating self-assembly behavior independent of exogenous excipients. The resulting SNM could be further refined by PEGylation with amphiphilic copolymers suitable for preclinical studies. Among these cabazitaxel derivatives, docosahexaenoic acid-derived compound 1 retained high antiproliferative activity. SNM assembled with compound 1 displayed an unexpected enhancement of tolerability in animals along with effective therapeutic efficacy in a mouse xenograft model of human cancer, compared with free drug administered in its clinical formulation. Overall, our studies showed how attaching flexible lipid chains to a hydrophobic and highly toxic anticancer drug can convert it to a systemic self-deliverable nanotherapy, preserving its pharmacologic efficacy while improving its safety profile. Cancer Res; 77(24); 6963-74. ©2017 AACR.

Fulvestrant reverses doxorubicin resistance in multidrug-resistant breast cell lines independent of estrogen receptor expression.

Drug resistance, a major obstacle to successful cancer chemotherapy, frequently occurs in recurrent or metastatic breast cancer and results in poor clinical response. Fulvestrant is a new type of selective estrogen receptor (ER) downregulator and a promising endocrine therapy for breast cancer. In this study, we evaluated the combination treatment of fulvestrant and doxorubicin in ER-negative multidrug-resistant (MDR) breast cancer cell lines Bads­200 and Bats­72. Fulvestrant potentiated doxorubicin-induced cytotoxicity, apoptosis and G2/M arrest with upregulation of cyclin B1. It functioned as a substrate for P-glycoprotein (P-gp) without affecting its expression. Furthermore, fulvestrant not only restored the intracellular accumulation of doxorubicin but also relocalized it to the nuclei in Bats­72 and Bads­200 cells, which may be another potential mechanism of reversal of P-gp mediated doxorubicin resistance. These results indicated that the combination of fulvestrant and doxorubicin-based chemotherapy may be feasible and effective for patients with advanced breast cancer.

Distinct characterization of two vinorelbine-resistant breast cancer cell lines developed by different strategies.

Resistance to chemotherapy is a major obstacle to the successful treatment of breast cancer patients. Recently, we successfully established two vinorelbine-resistant sublines, BC-DS and BC-TS, from the human breast cancer cell line BCap37, with different 'two-stage screening methods'. Interestingly, though BC-DS and BC-TS were developed from the same BCap37 cell line with the same drug, they showed remarkable differences. Compared with the parental BCap37 cells both BC-DS and BC-TS had resistance to vinorelbine, but the resistant characterizations are both unstable. BC-DS showed increased migration capability while BC-TS showed reduced migration capability. When investigating their multidrug resistance, we found BC-DS became more sensitive to methotrexate, which suggested that combination of MTX and vinorelbine could be a new treatment strategy. Moreover, BC-DS and BC-TS overexpressed P-glycoprotein at different levels. Our research also showed that the present clinical usage of vinorelbine is reasonable. These findings suggest that the vinorelbine-induced multiple drug resistance (MDR) sublines may be used as an in vitro model not only to further elucidate possible mechanisms of MDR involved in the human breast cancer, but also to find methods to optimize the curative effect of vinorelbine in clinic.

Reversal effects of Raloxifene on paclitaxel resistance in 2 MDR breast cancer cells.

Raloxifene hydrochloride (RAL), one of second generation of selective estrogen receptor modulators (SERMs), is usually used in preventing osteoporosis and breast cancer. The present study evaluated whether Raloxifene might sensitize multidrug resistant (MDR) breast cancers to chemotherapies, especially in estrogen receptor negative (ER-) breast cancer. The results showed that RAL could significantly sensitize ER- MDR breast tumors to paclitaxel both in vitro and in vivo. Combination of Raloxifene could significantly enhance paclitaxel-induced cell apoptosis, G2-M arrest as well as inhibition of cell proliferation in MDR tumors. Further studies showed that the combined treatment did not alter P-glycoprotein expression but increased P-gp ATPase activity. These results suggested that raloxifene might be a valuable chemosensitizer agent for breast cancer therapy.

Fulvestrant, a selective estrogen receptor down-regulator, sensitizes estrogen receptor negative breast tumors to chemotherapy.

Drug resistance frequently results in poor prognosis and high 5-year recurrence rate in estrogen receptor-negative (ER-) breast cancer patients. Herein, we examined the reversal effects of fulvestrant on multidrug resistance (MDR) in ER- breast cancer cells. Co-administration of fulvestrant significantly sensitized ER- MDR tumors to paclitaxel both in vitro and in vivo. Further analyses indicated that fulvestrant did not affect P-gp expression, but could inhibit P-gp function and subsequently reverse P-gp mediated drug resistance in ER- breast cancer cells. These results showed that combination of fulvestrant and chemotherapeutic agents might provide an effective treatment for ER- MDR breast cancers.