Biological Characteristics and Molecular Mechanisms of Fludioxonil Resistance in Fusarium graminearum in China

Fusarium graminearum is the primary causal agent of Fusarium head blight (FHB) of wheat. The phenylpyrrole fungicide fludioxonil is not currently registered for the management of FHB in China. The current study assessed the fludioxonil sensitivity of a total of 53 F. graminearum isolates collected from the six most important wheat-growing provinces of China during 2018 and 2019. The baseline fludioxonil sensitivity distribution indicated that all of the isolates were sensitive, exhibiting a unimodal cure with a mean effective concentration for 50% inhibition value of 0.13 ± 0.12 μg/ml (standard deviation). Five fludioxonil-resistant mutants were subsequently induced by exposure to fludioxonil under laboratory conditions. Ten successive rounds of subculture in the absence of the selection pressure indicated that the mutation was stably inherited. However, the fludioxonil-resistant mutants were found to have reduced pathogenicity, higher glycerol accumulation, and higher osmotic sensitivity than the parental wild-type isolates, indicating that there was a fitness cost associated with fludioxonil resistance. In addition, the study also found a positive cross resistance between fludioxonil, procymidone, and iprodione, but not with other fungicides such as boscalid, carbendazim, tebuconazole, and fluazinam. Sequence analysis of four candidate target genes (FgOs1, FgOs2, FgOs4, and FgOs5) revealed that the HBXT2R mutant contained two point mutations that resulted in amino acid changes at K223T and K415R in its FgOs1 protein, and one point mutation at residue 520 of its FgOs5 protein that resulted in a premature stop codon. Similarly, the three other mutants contained point mutations that resulted in changes at the K192R, K293R, and K411R residues of the FgOs5 protein but none in the FgOs2 and FgOs4 genes. However, it is important to point out that the FgOs2 and FgOs4 expression of all the fludioxonil-resistant mutants was significantly (P < 0.05) downregulated compared with the sensitive isolates (except for the SQ1-2 isolate). It was also found that one of the resistant mutants did not have changes in any of the sequenced target genes, indicating that an alternative mechanism could also lead to fludioxonil resistance.

Intracellular Restructured Reduced Glutathione-Responsive Peptide Nanofibers for Synergetic Tumor Chemotherapy

Self-assembled peptide nanofibers have been widely studied in cancer nanotherapeutics with their excellent biocompatibility and low toxicity of degradation products, showing the significant potential in inhibiting tumor progression. However, poor solubility prevents direct intravenous administration of nanofibers. Although water-soluble peptide precursors have been formed via the method of phosphorylation for intravenous administration, their opportunities for broad in vivo application are limited by the weak capacity of encapsulating drugs. Herein, we designed a novel restructured reduced glutathione (GSH)-responsive drug delivery system encapsulating doxorubicin for systemic administration, which achieved the intracellular restructuration from three-dimensional micelles into one-dimensional nanofibers. After a long blood circulation, micelles endocytosed by tumor cells could degrade in response to high GSH levels, achieving more release and accumulation of doxorubicin at desired sites. Further, the synergistic chemotherapy effects of self-assembled nanofibers were confirmed in both in vitro and in vivo experiments.

AIE/FRET-based versatile PEG-Pep-TPE/DOX nanoparticles for cancer therapy and real-time drug release monitoring

Based on the biological significance of self-assembling peptides in program cell death, promoting proliferation of stem cells and suppressing immune responses, stimuli-responsive polypeptide nanoparticles have attracted more and more attention.

FEAT expression correlates with tumor size, PR status, HER2 expression, Ki67 index, and molecular subtype and predicts recurrence in breast cancer

FEAT protein is uniformly overexpressed in a variety of human cancers but weakly expressed in normal tissue. FEAT has antiapoptotic activity and plays a role in carcinogenesis; however, the correlation between FEAT and clinicopathologic characteristics in cancer has not been reported. Our study explores the expression of FEAT protein and its clinicopathologic significance in breast cancer. We examined the expression of FEAT in tissues from 131 cases of breast cancer by immunohistochemistry and analyzed the correlation between FEAT expression and clinicopathologic parameters. The difference in FEAT expression between normal breast tissues and breast cancer tissues was also investigated. Finally, we analyzed the association between FEAT expression and disease-free survival or overall survival. Our data showed that FEAT was expressed in the cytoplasm. The expression of FEAT protein was significantly higher in breast cancer tissues than in normal breast tissues. Moreover, the expression of FEAT protein was higher in breast cancer with a larger tumor size (>2 cm), negative PR, positive HER2, or higher Ki67 index (≥14%) than in breast cancer with a smaller tumor size (≤2 cm), positive PR, negative HER2, or lower Ki67 index (<14%) (P<0.05). In addition, the expression of FEAT protein was associated with tumor size, PR status, HER2 expression, Ki67 index, and molecular subtype. Survival analysis showed that disease-free survival and overall survival were significantly shorter in breast cancer patients with high FEAT expression than in those with low expression of FEAT (P<0.05). COX regression analysis showed that FEAT was an independent prognostic factor for recurrence in breast cancer, but not for survival. In conclusion, FEAT may be a potential biomarker for recurrence of breast cancer.

Cisplatin and Fluorouracil Induction Chemotherapy With or Without Docetaxel in Locoregionally Advanced Nasopharyngeal Carcinoma

In this study, we aim to compare the progression-free survival (PFS) rates and side effects of induction chemotherapy based on docetaxel, cisplatin and fluorouracil (TPF) versus cisplatin and fluorouracil (PF) in patients with locoregionally-advanced nasopharyngeal carcinoma who received subsequent chemoradiotherapy. We randomly assigned 278 patients with stage III or IV NPC (without distant metastases) to receive either TPF or PF induction chemotherapy, followed by cisplatin-based chemoradiotherapy every 3 weeks and intensity-modulated radiation therapy for 5 days per week. After a minimum of 2 years follow-up, a PFS benefit was observed for TPF compared to PF, though this difference was not statistically significant (84.5% vs. 77.9%, P = .380). Due to increased frequencies of grade 3 or 4 neutropenia and diarrhea, significantly more patients in the TPF group required treatment delays and dose modifications. Our findings suggest that PF induction chemotherapy has substantially better tolerance and compliance rates than TPF induction chemotherapy. However, the treatment efficacy of PF is not superior to TPF induction chemotherapy in patients with locoregionally-advanced NPC (ClinicalTrials.gov number, NCT01536223).

Mitochondrial Targeted Doxorubicin-Triphenylphosphonium Delivered by Hyaluronic Acid Modified and pH Responsive Nanocarriers to Breast Tumor: in Vitro and in Vivo Studies

Multidrug resistance (MDR) is the major obstacle for chemotherapy. In a previous study, we have successfully synthesized a novel doxorubicin (DOX) derivative modified by triphenylphosphonium (TPP) to realize mitochondrial delivery of DOX and showed the potential of this compound to overcome DOX resistance in MDA-MB-435/DOX cells. (1) To introduce specificity for DOX-TPP to cancer cells, here we report on the conjugation of DOX-TPP to hyaluronic acid (HA) by hydrazone bond with adipic acid dihydrazide (ADH) as the acid-responsive linker, producing HA- hydra-DOX-TPP nanoparticles. Hyaluronic acid (HA) is a natural water-soluble linear glycosaminoglycan, which was hypothesized to increase the accumulation of nanoparticles containing DOX-TPP in the mitochondria of tumor cells upon systemic administration, overcoming DOX resistance, in vivo. Our results showed HA- hydra-DOX-TPP to self-assemble to core/shell nanoparticles of good dispersibility and effective release of DOX-TPP from the HA- hydra-DOX-TPP conjugate in cancer cells, which was followed by enhanced DOX mitochondria accumulation. The HA- hydra-DOX-TPP nanoparticles also showed improved anticancer effects, better tumor cell apoptosis, and better safety profile compared to free DOX in MCF-7/ADR bearing mice.

MMP-2-Sensitive HA End-Conjugated Poly(amidoamine) Dendrimers via Click Reaction To Enhance Drug Penetration into Solid Tumor

Currently, the limited penetration of nanoparticles remains a major challenge for antitumor nanomedicine to penetrate into the tumor tissues. Herein, we propose a size-shrinkable drug delivery system based on a polysaccharide-modified dendrimer with tumor microenvironment responsiveness for the first time to our knowledge, which was formed by conjugating the terminal glucose of hyaluronic acid (HA) to the superficial amidogen of poly(amidoamine) (PAMAM), using a matrix metalloproteinase-2 (MMP-2)-cleavable peptide (PLGLAG) via click reaction. These nanoparticles had an initial size of ∼200 nm, but once deposited in the presence of MMP-2, they experienced a dramatic and fast size change and dissociated into their dendrimer building blocks (∼10 nm in diameter) because of cleavage of PLGLAG. This rapid size-shrinking characteristic not only promoted nanoparticle extravasation and accumulation in tumors benefited from the enhanced permeability and retention effect but also achieved faster nanoparticle diffusion and penetration. We have further conducted comparative studies of MMP-2-sensitive macromolecules (HA-pep-PAMAM) and MMP-2-insensitive macromolecules (HA-PAMAM) synthesized with a similar particle size, surface charge, and chemical composition and evaluated in both monolayer cells and multicellular spheroids. The results confirmed that the enzyme-responsive size shrink is an implementable strategy to enhance drug penetration and to improve therapeutic efficacy. Meanwhile, macromolecule-based nanoparticles with size-variable characteristics not only promote drug penetration, but they can also be used as gene delivery systems, suggesting great potential as nano-delivery systems.

Modified-FOLFIRINOX in metastatic pancreatic cancer: A prospective study in Chinese population

FOLFIRINOX chemotherapy has shown remarkable responses in patients with metastatic pancreatic cancer (MPC), and has significantly improved prognosis. However, FOLFIRINOX is currently not frequently applied in China because of its high incidence of adverse events, and there is no recognized optimization for this therapy in Chinese population. Modification of FOLFIRINOX may be better for its acceptance in China. In this study, we evaluated the efficacy and safety of modified-FOLFIRINOX in patients with MPC. A total of 62 MPC patients were treated with modified-FOLFIRINOX (no Fluorouracil bolus, 85% Oxaliplatin and 75% Irinotecan) between April 2014 and April 2017 in our institute. 40 of them were evaluated, with a response rate of 32.5% (13/40). The frequent grade 3/4 adverse events are neutropenia (29%) and alanine aminotransferase elevation (14.5%). No treatment-related death was observed. The median overall survival and median progression-free survival are 10.3 months and 7.0 months, respectively. In conclusion, modified-FOLFIRINOX had significantly improved tolerance with similar efficacy to FOLFIRINOX. These findings may provide evidence for the use of FOLFIRINOX in Chinese patients with MPC.

HER2 overexpression reverses the relative resistance of EGFR-mutant H1975 cell line to gefitinib

Gefitinib is an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) that has been demonstrated to be clinically useful for the treatment of patients with non-small cell lung cancer (NSCLC). However, ~50% of patients do not respond to EGFR TKI treatment through the emergence of mutations, such as T790M. Therefore, it is important to determine which patients are eligible for treatment with gefitinib. As a preferred dimerization partner for EGFR, the role of EGFR 2 (HER2) in mediating sensitivity to gefitinib is poorly understood. In the present study, full-length human HER2 cDNA was introduced to the NSCLC cell lines H1975 and H1299, which have a low endogenous expression level of HER2. In addition, it was observed in the present study that the H1975 cell line harbored the L858R and T790M mutations in the EGFR kinase domain. Western blot analysis and MTT assay were used to evaluate the TKI sensitivity of HER2 expression status, and the activation of HER3 and HER2 downstream effectors. The results indicated that the sensitivity of H1975 cells to gefitinib was restored by the overexpression of HER2, which stimulated HER2-driven signaling cascades accompanied by the activation of protein kinase B. By contrast, ectopic HER2 overexpression in H1299 cells did not significantly alter the sensitivity to gefitinib treatment. In conclusion, the current study results suggested that the relatively resistance of the H1975 cell line to gefitinib could be reversed by the overexpression of HER2. Therefore, the expression of HER2 could also be considered when evaluate the patients' potential response to gefitinib, particularly in the subgroup of lung cancer patients who harbor an EGFR mutation.

Chemosensitization and radiosensitization of a lung cancer cell line A549 induced by a composite polymer micelle

Multidrug resistance (MDR) to Doxorubicin (DOX) remains a major obstacle to successful cancer treatment. The present study sought to overcome the MDR of lung cancer cells and achieve radiosensitization by developing a composite DOX-loaded micelle (M-DOX). M-DOX containing PEG-PCL/Pluronic P105 was prepared by the solvent evaporation method. Lung cancer cell line A549 was adopted in this study. In vitro cytotoxicity, cellular uptake behavior, subcellular distribution, and radiosensitivity were evaluated by the treatment with M-DOX, and free DOX was used as a control. A549 cells treated with M-DOX as opposed to free DOX showed greater cellular uptake as well as greater cytotoxicity. Furthermore, M-DOX reached the mitochondria and lysosome effectively after cellular uptake, and fluorescence used to track M-DOX was found to be surrounding the nucleus. Finally, colony-forming assays demonstrated that M-DOX treatment improved radiosensitization when compared to free DOX. Based on the increased cytotoxicity and radiosensitization, M-DOX could be considered as a promising drug delivery system to overcome MDR in lung cancer therapy.

Doxorubicin-mediated radiosensitivity in multicellular spheroids from a lung cancer cell line is enhanced by composite micelle encapsulation

Background

The purpose of this study is to evaluate the efficacy of composite doxorubicinloaded micelles for enhancing doxorubicin radiosensitivity in multicellular spheroids from a non-small cell lung cancer cell line.

Methods

A novel composite doxorubicin-loaded micelle consisting of polyethylene glycolpolycaprolactone/Pluronic P105 was developed, and carrier-mediated doxorubicin accumulation and release from multicellular spheroids was evaluated. We used confocal laser scanning microscopy and flow cytometry to study the accumulation and efflux of doxorubicin from A549 multicellular spheroids. Doxorubicin radiosensitization and the combined effects of irradiation and doxorubicin on cell migration and proliferation were compared for the different doxorubicin delivery systems.

Results

Confocal laser scanning microscopy and quantitative flow cytometry studies both verified that, for equivalent doxorubicin concentrations, composite doxorubicin-loaded micelles significantly enhanced cellular doxorubicin accumulation and inhibited doxorubicin release. Colony-forming assays demonstrated that composite doxorubicin-loaded micelles are radiosensitive, as shown by significantly reduced survival of cells treated by radiation + composite micelles compared with those treated with radiation + free doxorubicin or radiation alone. The multicellular spheroid migration area and growth ability verified higher radiosensitivity for the composite micelles loaded with doxorubicin than for free doxorubicin.

Conclusion

Our composite doxorubicin-loaded micelle was demonstrated to have radiosensitization. Doxorubicin loading in the composite micelles significantly increased its cellular uptake, improved drug retention, and enhanced its antitumor effect relative to free doxorubicin, thereby providing a novel approach for treatment of cancer.

Doxorubicin-loaded PEG-PCL copolymer micelles enhance cytotoxicity and intracellular accumulation of doxorubicin in adriamycin-resistant tumor cells

Background

Multidrug resistance remains a major obstacle to successful cancer chemotherapy. Some chemical multidrug resistance inhibitors, such as ciclosporin and verapamil, have been reported to reverse resistance in tumor cells. However, the accompanying side effects have limited their clinical application. In this study, we have developed a novel drug delivery system, ie, a polyethyleneglycol-polycaprolactone (PEG-PCL) copolymer micelle encapsulating doxorubicin, in order to circumvent drug resistance in adriamycin-resistant K562 tumor cells.

Methods

Doxorubicin-loaded diblock copolymer PEG-PCL micelles were developed, and the physicochemical properties of these micelles, and accumulation and cytotoxicity of doxorubicin in adriamycin-resistant K562 tumor cells were studied.

Results

Doxorubicin-loaded micelles were prepared using a solvent evaporation method with a diameter of 36 nm and a zeta potential of +13.8 mV. The entrapment efficiency of doxorubicin was 48.6% ± 2.3%. The micelles showed sustained release, increased uptake, and cellular cytotoxicity, as well as decreased efflux of doxorubicin in adriamycin-resistant K562 tumor cells.

Conclusion

This study suggests that PEG-PCL micelles have the potential to reverse multidrug resistance in tumor cells.

Isolation and characterization of radiation-resistant lung cancer D6-R cell line

OBJECTIVE

To isolate an isogenic radioresistant cancer cell line after fractioned X-ray radiation and characterize the resistant cells.

METHODS

D6 cells were exposed to repeated X-ray irradiation, and after a total dose of 5200 cGy in 8 fractions, a radioresistant monoclone D6-R was obtained. The radiosensitivity and drug sensitivity of the novel radioresistant D6-R cells, together with their parent D6 cells, were measured using clonogenic assay and MTT assay respectively. Cell cycle distribution was analyzed by flow cytometry. Fluorescence microscopy and flow cytometry were applied for apoptosis detection. Comet assay was used for the detection of DNA damage and repair.

RESULTS

D6-R cells showed higher and broader initial shoulder (D0=2.08 Gy, Dq=1.64 Gy, N=2.20) than the parent D6 cells (D0=1.84 Gy, Dq=0.34 Gy, N=1.20). They were 1.65-fold more radioresistant than D6 cells in terms of SF2 (63% vs 38%) and were more resistant to ADM (3.15-fold) and 5-FU (3.86-fold) as compared with the latter. It was found that D6-R cells had higher fractions of cells in S phase (53.4% vs 37.8%) and lower fractions of cells in G1 (44.1% vs 57.2%) and G2-M phase (2.5% vs 5%). There was no difference in radiation-induced apoptosis between D6-R and D6 cells. D6-R cells showed less initial DNA damage and increased capacity in DNA repair after irradiation, as compared with the parent cells.

CONCLUSIONS

D6-R cells have been isolated by exposing the parental D6 cells to repeated irradiation. The difference in cell cycle pattern together with the induction and repair of DNA damage might, at least partially, explain the mechanism of the radioresistance.

Medullary hemorrhagic infarction after radiation for nasopharyngeal carcinoma

Head and neck irradiation may lead to accelerated atherosclerosis over several years. Delayed stroke has been described after head and neck irradiation administered for a number of conditions. However, brain stem stroke has only rarely been associated with irradiation. We report a patient with medullary hemorrhagic infarction 6 years after radiotherapy for nasopharyngeal carcinoma. A 42-year-old normotensive Chinese male had rapid onset of vertigo, diplopia, ataxia, dysphagia, hypophonic dysarthria, hemiparesis, and respiratory distress. Cranial MR imaging 2 days after symptom onset showed medullary infarction, and cranial MR imaging 5 days after symptom onset showed medullary hemorrhage. He needed ventilatory support and died of bacterial pneumonia 1 month later. Other risk factors for stroke were absent. Hemorrhagic infarction in this patient was likely associated with the radiotherapy. Radiotherapy is the first choice of treatment for nasopharyngeal carcinoma, however, it may induce fatal medullary hemorrhagic infarction.