Dual pH/redox-responsive hyperbranched polymeric nanocarriers with TME-trigger size shrinkage and charge reversible ability for amplified chemotherapy of breast cancer.

A novel pH/redox-responsive hyperbranched MeO-PEG-b-(NIPAAm-co-PBAE) nanoparticles (NPs) were designed with size shrinkage and charge-reversible potential for targeted delivery of docetaxel (DTX) to MDA-MB-231 cell lines. In the tumor microenvironment (TME), amine protonation induces charge reversal and disulfide bond cleavage under high TME GSH concentration causing size shrinkage, improved deep tumor penetration, and active targeting of the therapeutic agents. These nano drug delivery systems (NDDSs) significantly promoted cancer cell uptake (~ 100% at 0.5 h), facilitating site-specific delivery and deep tumor penetration. The MTT assay revealed significantly higher cytotoxicity (P value < 0.0001) for DTX-loaded NPs compared to free DTX. Cell cycle analysis revealed G2/M (58.3 ± 2.1%) and S (21.5 ± 1.3%) arrest for DTX-loaded NPs, while free DTX caused G2/M (67.9 ± 1.1%) and sub-G1 (10.3 ± 0.8%) arrest. DTX-loaded NPs induced higher apoptosis (P value < 0.001) in MDA-MB-231 cells (71.5 ± 2.8%) compared to free DTX (42.3 ± 3.1%). Western blotting and RT-PCR assays confirmed significant up-regulation of protein levels and apoptotic genes by DTX-loaded NPs compared to free DTX. In conclusion, TME-responsive charge reversal and size-shrinkable smart NDDSs designed based on low pH, and high glutathione (GSH), offer more effective site-specific delivery of therapeutic agents to tumors.

Co-transcriptional R-loops-mediated epigenetic regulation drives growth retardation and docetaxel chemosensitivity enhancement in advanced prostate cancer.

R-loops are prevalent three-stranded nucleic acid structures, comprising a DNA-RNA hybrid and a displaced single-stranded DNA, that frequently form during transcription and may be attributed to genomic stability and gene expression regulation. It was recently discovered that RNA modification contributes to maintain the stability of R-loops such as N6-methyladenosine (m6A). Yet, m6A-modified R-loops in regulating gene transcription remains poorly understood. Here, we demonstrated that insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs) recognize R-loops in an m6A-dependent way. Consequently, IGF2BPs overexpression leads to increased overall R-loop levels, cell migration inhibition, and cell growth retardation in prostate cancer (PCa) via precluding the binding of DNA methyltransferase 1(DNMT1) to semaphorin 3 F (SEMA3F) promoters. Moreover, the K homology (KH) domains of IGF2BPs are required for their recognition of m6A-containing R-loops and are required for tumor suppressor functions. Overexpression of SEMA3F markedly enhanced docetaxel chemosensitivity in prostate cancer via regulating Hippo pathway. Our findings point to a distinct R-loop resolution pathway mediated by IGF2BPs, emphasizing the functional importance of IGF2BPs as epigenetic R-loop readers in transcriptional genetic regulation and cancer biology.The manuscript summarizes the new role of N6-methyladenosine in epigenetic regulation, we introduce the distinct R-loop resolution mediated by IGF2BP proteins in an m6A-dependent way, which probably lead to the growth retardation and docetaxel chemotherapy resistance in prostate cancer. Moreover, our findings first emphasized the functional importance of IGF2BPs as epigenetic R-loop readers in transcriptional genetic regulation and cancer biology. In addition, our research provides a novel RBM15/IGF2BPs/DNMT1 trans-omics regulation m6A axis, indicating the new crosstalk between RNA m6A methylation and DNA methylation in prostate cancer.

Unleashing a safe and potent pro-senescence anti-tumor strategy.

Inducing senescence in tumor cells can stimulate anti-tumor immune responses. In this issue of Cancer Cell, Colucci et al. demonstrate that the combination of the RAR agonist Adapalene with the chemotherapy drug Docetaxel enhances tumor-suppressing senescence and activates an anti-tumor immune response through natural killer cells.

Engineered nanomicelles inhibit the tumour progression via abrogating the prostaglandin-mediated immunosuppression.

Cancer treatment is challenged due to immunosuppressive inflammatory tumour microenvironment (TME) caused by infiltration of tumour-promoting and inhibition of tumour-inhibiting immune cells. Here, we report the engineering of chimeric nanomicelles (NMs) targeting the cell proliferation using docetaxel (DTX) and inflammation using dexamethasone (DEX) that alters the immunosuppressive TME. We show that a combination of phospholipid-DTX conjugate and PEGylated-lipid-DEX conjugate can self-assemble to form sub-100 nm chimeric NMs (DTX-DEX NMs). Anti-cancer activities against syngeneic and xenograft mouse models showed that the DTX-DEX NMs are more effective in tumour regression, enhance the survival of mice over other treatment modes, and alter the tumour stroma. DTX-DEX NMs cause a significant reduction in myeloid-derived suppressor cells, alter the polarization of macrophages, and enhance the accumulation of cytotoxic CD4+ and CD8+ T cells in tumour tissues, along with alterations in cytokine expression. We further demonstrated that these DTX-DEX NMs inhibit the synthesis of prostaglandins, especially PGE2, by targeting the cyclooxygenase 2 that is partly responsible for immunosuppressive TME. Therefore, this study presents, for the first time, the engineering of lithocholic acid-derived chimeric NMs that affect the prostaglandin pathway, alter the TME, and mitigate tumour progression with enhanced mice survival.

Synthesis and in vitro antitumor activity of galactosamine-docetaxel conjugates.

Docetaxel (DTX) is a semi-synthetic analogue of paclitaxel which has attracted extensive attention in the treatment of cancer. However, the current clinically used DTX formulations display low tumor targeting ability, leading to unsatisfactory therapeutic outcomes with adverse effects, which poses significant challenges to the clinical application. In this study, three galactosamine (Gal) and docetaxel conjugates with different linkers were synthesized, namely DTX-(suc-Gal)2, DTX-(DTDPA-Gal)2, and DTX-(DSeDPA-Gal)2. These three conjugates were characterized by 1H NMR, FT-IR and HRMS. The in vitro drug release study shows that DTX-(DTDPA-Gal)2 and DTX-(DSeDPA-Gal)2 exhibit glutathione (GSH)-responsive drug release and DTX-(DSeDPA-Gal)2 displays higher GSH-responsiveness. The in vitro antitumor activity study shows that DTX-(DTDPA-Gal)2 and DTX-(DSeDPA-Gal)2 exhibit enhanced cytotoxicity, cell apoptosis rate and G2/M phase arrest against HepG2 cells as compared to DTX-(suc-Gal)2, DTX-(DSeDPA-Gal)2 displays the highest cytotoxicity, cell apoptosis rate and G2/M phase arrest among these three conjugates. In addition, DTX-(DSeDPA-Gal)2 exhibits higher selectivity to HepG2 cells as compared to free DTX. The DTX-(DSeDPA-Gal)2 developed in this study has been proven to be an effective DTX conjugate for selective killing hepatoma cells.

Single-cell deconvolution algorithms analysis unveils autocrine IL11-mediated resistance to docetaxel in prostate cancer via activation of the JAK1/STAT4 pathway.

BACKGROUND: Docetaxel resistance represents a significant obstacle in the treatment of prostate cancer. The intricate interplay between cytokine signalling pathways and transcriptional control mechanisms in cancer cells contributes to chemotherapeutic resistance, yet the underlying molecular determinants remain only partially understood. This study elucidated a novel resistance mechanism mediated by the autocrine interaction of interleukin-11 (IL-11) and its receptor interleukin-11 receptor subunit alpha(IL-11RA), culminating in activation of the JAK1/STAT4 signalling axis and subsequent transcriptional upregulation of the oncogene c-MYC. METHODS: Single-cell secretion profiling of prostate cancer organoid was analyzed to determine cytokine production profiles associated with docetaxel resistance.Analysis of the expression pattern of downstream receptor IL-11RA and enrichment of signal pathway to clarify the potential autocrine mechanism of IL-11.Next, chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) was performed to detect the nuclear localization and DNA-binding patterns of phosphorylated STAT4 (pSTAT4). Coimmunoprecipitation and reporter assays were utilized to assess interaction between pSTAT4 and the cotranscription factor CREB-binding protein (CBP) as well as their role in c-MYC transcriptional activity. RESULTS: Autocrine secretion of IL-11 was markedly increased in docetaxel-resistant prostate cancer cells. IL-11 stimulation resulted in robust activation of JAK1/STAT4 signalling. Upon activation, pSTAT4 translocated to the nucleus and associated with CBP at the c-MYC promoter region, amplifying its transcriptional activity. Inhibition of the IL-11/IL-11RA interaction or disruption of the JAK1/STAT4 pathway significantly reduced pSTAT4 nuclear entry and its binding to CBP, leading to downregulation of c-MYC expression and restoration of docetaxel sensitivity. CONCLUSION: Our findings identify an autocrine loop of IL-11/IL-11RA that confers docetaxel resistance through the JAK1/STAT4 pathway. The pSTAT4-CBP interaction serves as a critical enhancer of c-MYC transcriptional activity in prostate cancer cells. Targeting this signalling axis presents a potential therapeutic strategy to overcome docetaxel resistance in advanced prostate cancer.

CircTHSD4 promotes the malignancy and docetaxel (DTX) resistance in prostate cancer by regulating miR-203/HMGA2 axis.

Objective: Circular ribose nucleic acids (circRNAs) are implicated in tumor progression and drug resistance of prostate cancer (PCa). The current work explored the function of circ_0005203 (circTHSD4) in the malignancy and docetaxel (DTX) resistance of PCa. Methods: circTHSD4 expression within PCa as well as matched non-carcinoma samples was measured through real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, a subcellular fraction assay was conducted to determine circTHSD4 subcellular localization within PCa cells. In addition, we performed a Western blot (WB) assay to detect high-mobility-group A2 protein (HMGA2) levels. Besides, functional associations of two molecules were investigated through dual luciferase reporter assay. Cell Counting Kit (CCK)-8, colony formation together with Transwell assay was conducted to assess malignant phenotypes of PCa cells, whereas flow cytometry was performed to determine cell apoptosis. Furthermore, a xenograft mouse model was constructed to verify the effect of circTHSD4 on the carcinogenesis of PCa cells. Results: According to RT-qPCR results, circTHSD4 was up-regulated within PCa tissues and cells, which predicted the dismal prognostic outcome of PCa cases. circTHSD4 silencing within PCa cells markedly suppressed cell growth, migration, and colony formation. circTHSD4 silencing remarkably elevated PCa cell apoptosis and carcinogenesis within the xenograft model. Further, circTHSD4 silencing enhanced docetaxel (DTX) sensitivity in PCa cells. Furthermore, we demonstrated that circTHSD4 modulated the malignancy of PCa cells by regulating HMGA2 expression through sponging miR-203. Conclusion: Together, our findings suggest that circTHSD4 overexpression could promote the malignant phenotype and DTX resistance in PCa through the regulation of the miR-203/HMGA2 axis.

Capivasertib combines with docetaxel to enhance anti-tumour activity through inhibition of AKT-mediated survival mechanisms in prostate cancer.

BACKGROUND/OBJECTIVE: To explore the anti-tumour activity of combining AKT inhibition and docetaxel in PTEN protein null and WT prostate tumours. METHODS: Mechanisms associated with docetaxel capivasertib treatment activity in prostate cancer were examined using a panel of in vivo tumour models and cell lines. RESULTS: Combining docetaxel and capivasertib had increased activity in PTEN null and WT prostate tumour models in vivo. In vitro short-term docetaxel treatment caused cell cycle arrest in the majority of cells. However, a sub-population of docetaxel-persister cells did not undergo G2/M arrest but upregulated phosphorylation of PI3K/AKT pathway effectors GSK3ß, p70S6K, 4E-BP1, but to a lesser extent AKT. In vivo acute docetaxel treatment induced p70S6K and 4E-BP1 phosphorylation. Treating PTEN null and WT docetaxel-persister cells with capivasertib reduced PI3K/AKT pathway activation and cell cycle progression. In vitro and in vivo it reduced proliferation and increased apoptosis or DNA damage though effects were more marked in PTEN null cells. Docetaxel-persister cells were partly reliant on GSK3ß as a GSK3ß inhibitor AZD2858 reversed capivasertib-induced apoptosis and DNA damage. CONCLUSION: Capivasertib can enhance anti-tumour effects of docetaxel by targeting residual docetaxel-persister cells, independent of PTEN status, to induce apoptosis and DNA damage in part through GSK3ß.

Methylation of GPRC5A promotes liver metastasis and docetaxel resistance through activating mTOR signaling pathway in triple negative breast cancer.

AIMS: This study aims to explore the function and mechanism of G Protein-coupled receptor class C group 5 member A (GPRC5A) in docetaxel-resistance and liver metastasis of breast cancer. METHODS: Single-cell RNA transcriptomic analysis and bioinformatic analysis are used to screen relevant genes in breast cancer metastatic hepatic specimens. MeRIP, dual-luciferase analysis and bioinformation were used to detect m6A modulation. Mass spectrometry (MS), co-inmunoprecipitation (co-IP) and immunofluorescence colocalization were executed to explore the mechanism of GPRC5A in breast cancer cells. RESULT: GPRC5A was upregulated in triple-negative breast cancer (TNBC) and was associated with a poor prognosis. In vitro and in vivo experiments demonstrated that knockdown of GPRC5A alleviated metastasis and resistance to docetaxel in TNBC. Overexpression of GPRC5A had the opposite effects. The m6A methylation of GPRC5A mRNA was modulated by METTL3 and YTHDF1, which facilitates its translation. GPRC5A inhibited the ubiquitination-dependent degradation of LAMTOR1, resulting in the recruitment of mTORC1 to lysosomes and activating the mTORC1/p70s6k signaling pathway. CONCLUSION: METTL3/YTHDF1 axis up-regulates GPRC5A expression by m6A methylation. GPRC5A activates mTORC1/p70s6k signaling pathway by recruiting mTORC1 to lysosomes, consequently promotes docetaxel-resistance and liver metastasis.

Manganese as a Possible Anticancer Enhancer in Docetaxel Treatment of Prostate Cancer Cells.

BACKGROUND/AIM: Treatment of castration-resistant prostate cancer with docetaxel (DOC) often leads to resistance. In this study, we investigated whether manganese (Mn) has the potential to enhance treatment when combined with DOC. MATERIALS AND METHODS: PC3 cells were exposed to DOC or Mn individually and in combination and cell viability was analysed in a dose- and time-dependent manner. Cell toxicity, cell cycle analysis and apoptotic protein levels were determined after 48 h of treatment. RESULTS: Mn in combination with different concentrations of DOC significantly enhanced the inhibitory effect on cell viability. Although the lowest dose did not cause mitotic arrest, DOC increased toxicity, which was reduced when combined with Mn. Protein analyses indicated that Mn compensates for the suppression of death receptors when combined with a low concentration of DOC and induced non-apoptotic pathways when combined with a higher concentration. CONCLUSION: Combining DOC and Mn may allow for a reduction in DOC concentration with the potential to reduce side effects.

Exploiting epigenetic targets to overcome taxane resistance in prostate cancer.

The development of taxane resistance remains a major challenge for castration resistant prostate cancer (CR-PCa), despite the effectiveness of taxanes in prolonging patient survival. To uncover novel targets, we performed an epigenetic drug screen on taxane (docetaxel and cabazitaxel) resistant CR-PCa cells. We identified BRPF reader proteins, along with several epigenetic groups (CBP/p300, Menin-MLL, PRMT5 and SIRT1) that act as targets effectively reversing the resistance mediated by ABCB1. Targeting BRPFs specifically resulted in the resensitization of resistant cells, while no such effect was observed on the sensitive compartment. These cells were successfully arrested at the G2/M phase of cell cycle and underwent apoptosis upon BRPF inhibition, confirming the restoration of taxane susceptibility. Pharmacological inhibition of BRPFs reduced ABCB1 activity, indicating that BRPFs may be involved in an efflux-related mechanism. Indeed, ChIP-qPCR analysis confirmed binding of BRPF1 to the ABCB1 promoter suggesting direct regulation of the ABCB1 gene at the transcriptional level. RNA-seq analysis revealed that BRPF1 knockdown affects the genes enriched in mTORC1 and UPR signaling pathways, revealing potential mechanisms underlying its functional impact, which is further supported by the enhancement of taxane response through the combined inhibition of ABCB1 and mTOR pathways, providing evidence for the involvement of multiple BRPF1-regulated pathways. Beyond clinical attributes (Gleason score, tumor stage, therapy outcome, recurrence), metastatic PCa databases further supported the significance of BRPF1 in taxane resistance, as evidenced by its upregulation in taxane-exposed PCa patients.

Cholinergic signaling via muscarinic M1 receptor confers resistance to docetaxel in prostate cancer.

Docetaxel is the most commonly used chemotherapy for advanced prostate cancer (PC), including castration-resistant disease (CRPC), but the eventual development of docetaxel resistance constitutes a major clinical challenge. Here, we demonstrate activation of the cholinergic muscarinic M1 receptor (CHRM1) in CRPC cells upon acquiring resistance to docetaxel, which is manifested in tumor tissues from PC patients post- vs. pre-docetaxel. Genetic and pharmacological inactivation of CHRM1 restores the efficacy of docetaxel in resistant cells. Mechanistically, CHRM1, via its first and third extracellular loops, interacts with the SEMA domain of cMET and forms a heteroreceptor complex with cMET, stimulating a downstream mitogen-activated protein polykinase program to confer docetaxel resistance. Dicyclomine, a clinically available CHRM1-selective antagonist, reverts resistance and restricts the growth of multiple docetaxel-resistant CRPC cell lines and patient-derived xenografts. Our study reveals a CHRM1-dictated mechanism for docetaxel resistance and identifies a CHRM1-targeted combinatorial strategy for overcoming docetaxel resistance in PC.

Docetaxel administered through a novel lymphatic drug delivery system (LDDS) improved treatment outcomes for lymph node metastasis.

Recently, sentinel lymph nodes (LNs) have been recognized as a starting point of hematogenous metastasis; thus, an increase in the control rate of LN metastasis is expected to improve the survival rate. Although surgical treatment and radiation therapy are commonly used for the radical treatment of LNs, these treatments are associated with lymphedema, pain, and an extended hospital stay. In a recent mouse study, activation of metastatic tumors in distant organs was reported after removing LNs, with or without metastasis to the LNs. Thus, there is the necessity for cancer treatment that can replace LN removal. Here, we evaluated the treatment efficacy of lymphatic drug delivery system (LDDS) with osmotic pressure and viscosity escalated Docetaxel at the early stage of LN metastasis. MXH10/Mo/lpr mice were inoculated with mouse breast cancer cells into Subiliac LN to create the metastatic mouse model. Docetaxel was injected into mouse mammary carcinoma cells inoculated LN as a single shot (SS) or double shot (DS) to understand the therapeutic mechanism of a single shot or double shot intervention using an in vivo imaging system, histology, and qPCR. The results showed that the DS administration of docetaxel at 1,960 kPa (12 mPa∙s) had better therapeutic outcomes with increased complete response and improved survival with reduced adverse events. The results also revealed that administration of a DS of docetaxel enhances differentiation of T helper cells, and improves survival and therapeutic outcomes. From a safety perspective, LDDS-administered DS of low-concentration docetaxel without any other anticancer treatments to LNs a novel approach to cancer management of LN metastasis. We emphasize that LDDS is a groundbreaking method of delivering anticancer drugs specifically to cancer susceptible LNs and is designed to enhance the effectiveness of cancer treatment while minimizing side effects.

Serine/threonine kinase 36 induced epithelial-mesenchymal transition promotes docetaxel resistance in prostate cancer.

To investigate the role and potential mechanism of serine/threonine kinase 36 (STK36) in docetaxel resistance-prostate cancer (PCa). The expression of STK36 in PCa and the correlation with clinicopathological characteristics of PCa patients were analyzed using the data from different databases and tissue microarrays. To investigate the role of STK36 on cell proliferation, invasion, and migration, STK36 was overexpressed and silenced in DU-145 and PC-3 cell lines. Cell counting kit-8 (CCK8) was used to test cell proliferation. Cell invasion and migration were detected by cell wound scratch assay and trans well, respectively. The expression profile of STK36, E-Cadherin, and Vimentin was analyzed by Western blot. Cell apoptosis was detected by the TUNEL assay. STK36 expression was upregulated in PCa tissue compared with adjacent benign PCa tissue; it was higher in patients with advanced stages compared with lower stages and was significantly correlated with decreased overall survival. Up-regulation of STK36 significantly promoted the proliferation, invasion, and migration of DU-145 and PC-3 cells and compensated for the suppression caused by docetaxel treatment in vitro. A striking apoptosis inhibition could be observed when dealing with docetaxel, although the apoptosis of DU-145 and PC-3 cells was not affected by the STK36 exclusive overexpression. Besides, E-Cadherin expression was restrained while the expression levels of vimentin were all enhanced. The knockdown of STK36 reversed the above process. STK36 up-regulation could accelerate the biological behavior and docetaxel resistance of PCa by epithelial-mesenchymal transition (EMT) activation. STK36 may be potentially used as a target in PCa resolvent with docetaxel.

Durvalumab and taxane family combination therapy enhances the antitumoral effects for NSCLC: An in vitro study.

Immunotherapy has lately become the most preferred cancer treatment method, and for non-small cell lung cancer (NSCLC) first-line treatment, there are many immunotherapy options. This study aimed to assess the effectiveness and toxicity of paclitaxel (PTX), docetaxel (DTX) chemotherapy, immune checkpoint inhibitor treatment (durvalumab; DVL), and their combination in NSCLC. A-549 cells were treated with DVL in combination with PTX and DTX (a quarter of the IC50 ) to investigate their anticancer effects on these cells. The MTT assay, wound healing tests, and double-staining with Annexin V/PI were used to assess the cell viability, apoptosis, and migration. The results showed that a combination of 0.35 mg/mL DVL with 6.5 µg/mL PTX and 1.75 µg/mL DTX produced a synergistic effect with CI values of 0.88, 0.37, and 0.81, respectively. Moreover, the PTX + DTX + DVL combination led to a significantly increased apoptotic rate up to 88.70 ± 3.39% in the A549 cell line compared to monotherapy (p < .001). In addition, we found that the combination therapy with these agents increased the expression level of Bax, Cas-3, p53, and Bax/Bcl-2 ratio in all experimental groups. In conclusion, the results suggest that combining anti-PD-L1 antibody therapy with chemotherapy may provide a promising approach to enhance treatment outcomes and be a potentially efficacious strategy for treating NSCLC patients. Further research and clinical investigations are needed to elucidate the underlying molecular mechanisms and validate the therapeutic potential of these compounds in vivo.

EGFR-mediated hyperacetylation of tubulin induced docetaxel resistance by downregulation of HDAC6 and upregulation of MCAK and PLK1 in prostate cancer cells.

Docetaxel-based chemotherapy has generally been considered as one of the effective treatments for castration-resistant prostate cancer (PCa). However, clinical treatment with docetaxel often encounters a number of undesirable effects, including drug resistance. Tubulin isoforms have been previously examined for their resistance to docetaxel in many cancers, but their real mechanisms remained unclear. In this study, a series of docetaxel-resistant PC/DX cell sublines were established by chronically exposing PC3 to progressively increased concentrations of docetaxel. Western blotting results showed significantly higher expression of acetyl-tubulin, α-tubulin, ß-tubulin, γ-tubulin, and ßIII-tubulin in PC/DX25 than in parental PC3 cells. PC/DX25 with greater resistance to docetaxel had higher levels of acetyl-tubulin and mitotic centromere-associated kinesin (MCAK) than PC3 cells. This study found that docetaxel induced the expression of acetyl-tubulin and MCAK in PC3 cells at a dose- and time-dependent manner. Both mRNA and protein levels of histone deacetylase 6 (HDAC6) were significantly decreased in PC/DX25 compared with PC3 cells. PC3 increased the resistance to docetaxel by HDAC6 knockdown and Tubastatin A (HDAC6 inhibitor). Conversely, PC/DX25 reversed the sensitivity to docetaxel by MCAK knockdown. Notably, flow cytometry analysis revealed that MCAK knockdown induced significantly sub G1 fraction in PC/DX cells. Overexpression of polo-like kinase-1 increased the cell survival rate and resistance to docetaxel in PC3 cells. Moreover, epidermal growth factor receptor (EGFR) activation induced the upregulation of acetyl-tubulin in docetaxel-resistant PCa cells. These findings demonstrated that the EGFR-mediated upregulated expression of acetyl-tubulin played an important role in docetaxel-resistant PCa.

Docetaxel Inhibits Epithelial-Mesenchymal Transition in Human Mammary Cells.

Epithelial-mesenchymal transition (EMT) is a reversible and dynamic biological process in which epithelial cells acquire mesenchymal characteristics including enhanced stemness and migratory ability. EMT can facilitate cancer metastasis and is a known driver of cellular resistance to common chemotherapeutic drugs, such as docetaxel. Current chemotherapeutic practices such as docetaxel treatment can promote EMT and increase the chance of tumor recurrence and resistance, calling for new approaches in cancer treatment. Here we show that prolonged docetaxel treatment at a sub-IC50 concentration inhibits EMT in immortalized human mammary epithelial (HMLE) cells. Using immunofluorescence, flow cytometry, and bulk transcriptomic sequencing to assess EMT progression, we analyzed a range of cellular markers of EMT in docetaxel-treated cells and observed an upregulation of epithelial markers and downregulation of mesenchymal markers in the presence of docetaxel. This finding suggests that docetaxel may have clinical applications not only as a cytotoxic drug but also as an inhibitor of EMT-driven metastasis and multidrug resistance depending on the concentration of its use.

Comparison of PLLA-PEG and PDLLA-PEG micelles for co-encapsulation of docetaxel and resveratrol.

The interest in combining chemosensitizers with cytostatics in cancer therapy is growing, which causes also a need to develop their delivery systems. Example of the combination with beneficial therapeutic effects is docetaxel (Dtx) and resveratrol (Res). Although poly(lactide)-co-poly(ethylene glycol) (PLA-PEG) micelles have been considered as one of the most promising platforms for drug delivery, their properties may depend on the stereoisomeric form of hydrophobic block. Therefore, the aim of this study was evaluation of the effect of PLA block on co-encapsulation and release rate of Dtx and Res, which has not been studied so far. This article presents a comparison of single- (Dtx or Res) and dual-drug (Dtx and Res) loaded micelles obtained from poly(l,l-lactide)-co-poly(ethylene glycol) (PLLA-PEG) and poly(d,l-lactide)-co-poly(ethylene glycol) (PDLLA-PEG). The analyzes of the micelles have been conducted including morphology, drug(s) encapsulation efficiency, intermolecular interactions, in vitro drug release, and cytotoxicity. Differences in drug loading ability and release profile have been observed between Res and Dtx but also depending on the polymer and number of drugs in micelles (single vs. dual loaded). The PLLA-PEG micelles have a significantly higher Dtx encapsulation capacity than PDLLA-PEG micelles. The highest cytotoxicity was shown for Dtx and Res dual-loaded micelles, regardless of the polymer. The findings may be used for selection of PLA-based drug delivery systems containing Dtx and Res.

Docetaxel radiosensitizes castration-resistant prostate cancer by downregulating CAV-1.

PURPOSE: Docetaxel (DXL), a noted radiosensitizer, is one of the few chemotherapy drugs approved for castration-resistant prostate cancer (CRPC), though only a fraction of CRPCs respond to it. CAV-1, a critical regulator of radioresistance, has been known to modulate DXL and radiation effects. Combining DXL with radiotherapy may create a synergistic anticancer effect through CAV-1 and improve CRPC patients' response to therapy. Here, we investigate the effectiveness and molecular characteristics of DXL and radiation combination therapy in vitro. MATERIALS AND METHODS: We used live/dead assays to determine the IC50 of DXL for PC3, DU-145, and TRAMP-C1 cells. Colony formation assay was used to determine the radioresponse of the same cells treated with radiation with/without IC50 DXL (4, 8, and 12 Gy). We performed gene expression analysis on public transcriptomic data collected from human-derived prostate cancer cell lines (C4-2, PC3, DU-145, and LNCaP) treated with DXL for 8, 16, and 72 hours. Cell cycle arrest and protein expression were assessed using flow cytometry and western blot, respectively. RESULTS: Compared to radiation alone, combination therapy with DXL significantly increased CRPC death in PC3 (1.48-fold, p < .0001), DU-145 (1.64-fold, p < .05), and TRAMP-C1 (1.13-fold, p < .05) at 4 Gy of radiation. Gene expression of CRPC treated with DXL revealed downregulated genes related to cell cycle regulation and upregulated genes related to immune activation and oxidative stress. Confirming the results, G2/M cell cycle arrest was significantly increased after treatment with DXL and radiation. CAV-1 protein expression was decreased after DXL treatment in a dose-dependent manner; furthermore, CAV-1 copy number was strongly associated with poor response to therapy in CRPC patients. CONCLUSIONS: Our results suggest that DXL sensitizes CRPC cells to radiation by downregulating CAV-1. DXL + radiation combination therapy may be effective at treating CRPC, especially subtypes associated with high CAV-1 expression, and should be studied further.

Improved Antitumor Efficacy of a Dextran-based Docetaxel-coupled Conjugate against Triple-Negative Breast Cancer.

BACKGROUND: Most chemotherapeutic agents are characterized by poor water solubility and non-specific distribution. Polymer-based conjugates are promising strategies for overcoming these limitations. OBJECTIVE: This study aims to fabricate a polysaccharide, dextran-based, dual-drug conjugate by covalently grafting docetaxel (DTX) and docosahexaenoic acid (DHA) onto the bifunctionalized dextran through a long linker, and to investigate the antitumor efficacy of this conjugate against breast cancer. METHODS: DTX was firstly coupled with DHA and covalently bounded with the bifunctionalized dextran (100 kDa) through a long linker to produce a conjugate dextran-DHA-DTX (termed C-DDD). Cytotoxicity and cellular uptake of this conjugate were measured in vitro. Drug biodistribution and pharmacokinetics were investigated through liquid chromatography/mass spectrometry analysis. The inhibitory effects on tumor growth were evaluated in MCF-7- and 4T1-tumor-bearing mice. RESULTS: The loading capacity of the C-DDD for DTX was 15.90 (weight/weight). The C-DDD possessed good water solubility and was able to self-assemble into nanoparticles measuring 76.8 ± 5.5 nm. The maximum plasma concentration and area under the curve (0-∞) for the released DTX and total DTX from the C-DDD were significantly enhanced compared with the conventional DTX formulation. The C-DDD selectively accumulated in the tumor, with limited distribution was observed in normal tissues. The C-DDD exhibited greater antitumor activity than the conventional DTX in the triplenegative breast cancer model. Furthermore, the C-DDD nearly eliminated all MCF-7 tumors in nude mice without leading to systemic adverse effects. CONCLUSION: This dual-drug C-DDD has the potential to become a candidate for clinical application through the optimization of the linker.