STK32C modulates doxorubicin resistance in triple-negative breast cancer cells via glycolysis regulation.

Understanding the mechanisms underlying doxorubicin resistance in triple-negative breast cancer (TNBC) holds paramount clinical significance. In our study, we investigate the potential of STK32C, a little-explored kinase, to impact doxorubicin sensitivity in TNBC cells. Our findings reveal elevated STK32C expression in TNBC specimens, associated with unfavorable prognosis in doxorubicin-treated TNBC patients. Subsequent experiments highlighted that STK32C depletion significantly augmented the sensitivity of doxorubicin-resistant TNBC cells to doxorubicin. Mechanistically, we unveiled that the cytoplasmic subset of STK32C plays a pivotal role in mediating doxorubicin sensitivity, primarily through the regulation of glycolysis. Furthermore, the kinase activity of STK32C proved to be essential for its mediation of doxorubicin sensitivity, emphasizing its role as a kinase. Our study suggests that targeting STK32C may represent a novel therapeutic approach with the potential to improve doxorubicin's efficacy in TNBC treatment.

MALSU1-mediated regulation of mitochondrial function governs proliferation and doxorubicin resistance in triple-negative breast cancer cells.

Triple-negative breast cancer (TNBC) poses a formidable challenge in oncology due to its aggressive nature and limited treatment options. Although doxorubicin, a widely used chemotherapeutic agent, shows efficacy in TNBC treatment, acquired resistance remains a significant obstacle. Our study explores the role of MALSU1, a regulator of mitochondrial translation, in TNBC and its impact on cell proliferation and doxorubicin resistance. We observed increased MALSU1 expression in TNBC, correlating with poor patient prognosis. MALSU1 knockdown in TNBC cells significantly reduced proliferation, indicating its pivotal role in sustaining cell growth. Mechanistically, MALSU1 depletion resulted in decreased activities of mitochondrial respiratory chain complexes, cellular ATP levels, and mitochondrial respiration. Notably, exogenous addition of normal mitochondria restored proliferation and mitochondrial respiration in MALSU1-depleted TNBC cells. Importantly, MALSU1 knockdown enhanced the sensitivity of doxorubicin-resistant TNBC cells to doxorubicin treatment. Furthermore, pharmacological inhibition of mitochondrial translation using tigecycline and chloramphenicol mimicked the effects of MALSU1 knockdown, suggesting mitochondrial translation as a potential therapeutic target. Taken together, our findings not only elucidate the intricate role of MALSU1 in TNBC biology and doxorubicin resistance but also lay the groundwork for future investigations targeting MALSU1 and/or mitochondrial translation as a promising avenue for developing innovative therapeutic strategies against TNBC.

USP10 suppresses ABCG2-induced malignant characteristics of doxorubicin-resistant thyroid cancer by inhibiting PI3K/AKT pathway.

Doxorubicin (DOX) is the most extensively used drug in the chemotherapy of thyroid cancer (TC). However, the existence of DOX resistance is not conducive to TC treatment. Here, we investigated the role of USP10 in DOX-resistant TC and explored the underlying molecular mechanism. CCK-8 assay was used to measure cell viability in thyroid cancer FTC133 and DOX-resistant FTC133-DOX cells. RT-qPCR and western blot were used to evaluate USP10 expression. Cell migration, invasion, and apoptotic assays were conducted. Western blot was used to detect cellular signaling proteins, EMT-related proteins, and apoptosis-related proteins. We found a lower expression of USP10 in the human TC cell line FTC133 as compared to the normal human thyroid Htori-3 cells. Notably, USP10 expression was further reduced in DOX-resistant (FTC133-DOX) cells compared to the FTC133 cells. FTC133-DOX cells had increased invasion, migration, and EMT properties while less apoptosis by activating the PI3K/AKT pathway. Interestingly, overexpressing USP10 increased the chemosensitivity of FTC133 cells to DOX therapy. Overexpressing USP10 inhibited invasion, migration, and EMT properties of FTC133-DOX cells and promoted apoptosis. Mechanistically, overexpressing USP10 inhibited PI3K/AKT pathway by activating PTEN. Furthermore, overexpressed USP10 controlled all these processes by downregulating ABCG2. This study demonstrates that USP10 could reduce DOX-induced resistance of TC cells to DOX therapy and could suppress TC malignant behavior by inhibiting the PI3K/AKT pathway. Furthermore, USP10 targeted ABCG2 to inhibit all these malignant processes, therefore, either increasing USP10 expression or inhibiting ABCG2 could be used as novel targets for treating DOX-resistant thyroid cancer.

KHDRBS3 accelerates glycolysis and promotes malignancy of hepatocellular carcinoma via upregulating 14-3-3ζ.

BACKGROUND: Primary hepatocellular carcinoma (HCC) is a malignancy with high morbidity and mortality. KH domain-containing, RNA-binding signal transduction-associated protein 3 (KHDRBS3) is an RNA-binding protein that is aberrantly expressed in multiple tumors; however, its expression and biological function in HCC have not been reported. METHODS: KHDRBS3 knockdown and overexpression were performed using the lentiviral vector system to investigate the effects of KHDRBS3 on cell proliferation, apoptosis, chemoresistance, and glycolysis. Murine xenograft tumor models were constructed to study the role of KHDRBS3 on tumor growth in vivo. Furthermore, RNA-Pull Down and RNA immunoprecipitation were utilized to explore the interaction between KHDRBS3 and 14-3-3ζ, a phosphopeptide-binding molecule encoded by YWHAZ. RESULTS: KHDRBS3 was highly expressed in human HCC tissues and predicted the poor prognosis of patients with HCC. Knockdown of KHDRBS3 exhibited a carcinostatic effect in HCC and impeded proliferation and tumor growth, reduced glycolysis, enhanced cell sensitivity to doxorubicin, and induced apoptosis. On the contrary, forced expression of KHDRBS3 expedited the malignant biological behaviors of HCC cells. The expression of KHDRBS3 was positively correlated with the expression of 14-3-3ζ. RNA immunoprecipitation and RNA pull-down assays demonstrated that KHDRBS3 bound to YWHAZ. We further confirmed that 14-3-3ζ silencing significantly reversed the promotion of proliferation and glycolysis and the inhibition of apoptosis caused by KHDRBS3 overexpression. CONCLUSIONS: Our findings suggest that KHDRBS3 promotes glycolysis and malignant progression of HCC through upregulating 14-3-3ζ expression, providing a possible target for HCC therapy.

Down-Regulation of CYP3A4 by the KCa1.1 Inhibition Is Responsible for Overcoming Resistance to Doxorubicin in Cancer Spheroid Models.

The large-conductance Ca2+-activated K+ channel, KCa1.1, plays a pivotal role in cancer progression, metastasis, and the acquisition of chemoresistance. Previous studies indicated that the pharmacological inhibition of KCa1.1 overcame resistance to doxorubicin (DOX) by down-regulating multidrug resistance-associated proteins in the three-dimensional spheroid models of human prostate cancer LNCaP, osteosarcoma MG-63, and chondrosarcoma SW-1353 cells. Investigations have recently focused on the critical roles of intratumoral, drug-metabolizing cytochrome P450 enzymes (CYPs) in chemoresistance. In the present study, we examined the involvement of CYPs in the acquisition of DOX resistance and its overcoming by inhibiting KCa1.1 in cancer spheroid models. Among the CYP isoforms involved in DOX metabolism, CYP3A4 was up-regulated by spheroid formation and significantly suppressed by the inhibition of KCa1.1 through the transcriptional repression of CCAAT/enhancer-binding protein, CEBPB, which is a downstream transcription factor of the Nrf2 signaling pathway. DOX resistance was overcome by the siRNA-mediated inhibition of CYP3A4 and treatment with the potent CYP3A4 inhibitor, ketoconazole, in cancer spheroid models. The phosphorylation levels of Akt were significantly reduced by inhibiting KCa1.1 in cancer spheroid models, and KCa1.1-induced down-regulation of CYP3A4 was reversed by the treatment with Akt and Nrf2 activators. Collectively, the present results indicate that the up-regulation of CYP3A4 is responsible for the acquisition of DOX resistance in cancer spheroid models, and the inhibition of KCa1.1 overcame DOX resistance by repressing CYP3A4 transcription mainly through the Akt-Nrf2-CEBPB axis.

A (Traditional Chinese Medicine) TCM-Inspired Doxorubicin Resistance Reversing Strategy: Preparation, Characterization, and Application of a Co-loaded pH-Sensitive Liposome.

In this study, nano-strategy for combined medication of active compounds from traditional Chinese medicine herbs was proposed to achieve the synergistic effects of inhibiting the doxorubicin (DOX) resistance, reducing the cardio-toxicity, and improving the treatment efficacy simultaneously. Dihydroartemisinin (DHA) and tetrandrine (TET) were co-delivered for the first time to treat DOX resistance of breast cancer with multi-pathway mechanism. Tumor micro-environment sensitivity prescription was adopted to enhance the reversal effect of DOX resistance nearly 50 times (resistance index, RI was 46.70) and uptake ability. The DHA-TET pH-sensitive liposomes (DHA-TET pH-sensitive LPs) had a good spherical structure and a uniform dispersion structure with particle size, polydispersity index (PDI), and zeta potential of 112.20 ± 4.80 nm, 0.20 ± 0.02, and - 8.63 ± 0.74 Mv, and was stable until 14 days under the storage environment of 4°C and for 6 months at room temperature environment. With the DOX resistance reversing ability increased, the inhibition effect of DHA-TET pH-sensitive LPs on both MCF-7/ADR cells and MCF-7 cells was significantly enhanced; meanwhile, the toxicity on cardiac cell (H9c2) was lowered. Ferroptosis induced by the DHA was investigated showing that the intracellular reactive oxygen species (ROS) and lipid peroxidation were increased to promote the synergistic effect through the due-loaded nano-carrier, providing a promising alternative for future clinical application.

Doxorubicin-Induced TrkAIII Activation: A Selection Mechanism for Resistant Dormant Neuroblastoma Cells.

Patients with advanced neuroblastoma (NB) receive multimodal clinical therapy, including the potent anthracycline chemotherapy drug doxorubicin (Dox). The acquisition of Dox resistance, however, is a major barrier to a sustained response and leads to a poor prognosis in advanced disease states, reinforcing the need to identify and inhibit Dox resistance mechanisms. In this context, we report on the identification and inhibition of a novel Dox resistance mechanism. This mechanism is characterized by the Dox-induced activation of the oncogenic TrkAIII alternative splice variant, resulting in increased Dox resistance, and is blocked by lestaurtinib, entrectinib, and crizotinib tyrosine kinase and LY294002 IP3-K inhibitors. Using time lapse live cell imaging, conventional and co-immunoprecipitation Western blots, RT-PCR, and inhibitor studies, we report that the Dox-induced TrkAIII activation correlates with proliferation inhibition and is CDK1- and Ca2+-uniporter-independent. It is mediated by ryanodine receptors; involves Ca2+-dependent interactions between TrkAIII, calmodulin and Hsp90; requires oxygen and oxidation; occurs within assembled ERGICs; and does not occur with fully spliced TrkA. The inhibitory effects of lestaurtinib, entrectinib, crizotinib, and LY294002 on the Dox-induced TrkAIII and Akt phosphorylation and resistance confirm roles for TrkAIII and IP3-K consistent with Dox-induced, TrkAIII-mediated pro-survival IP3K/Akt signaling. This mechanism has the potential to select resistant dormant TrkAIII-expressing NB cells, supporting the use of Trk inhibitors during Dox therapy in TrkAIII-expressing NBs.

Down-regulation of circITCH promotes osteosarcoma development and resistance to doxorubicin via the miR-524/RASSF6 axis.

BACKGROUND: Osteosarcoma (OS) is a malignant bone cancer, in which circular RNAs (circRNAs) act as important modulators. The present study aimed to explore the functional role of circRNA itchy E3 ubiquitin protein ligase (circITCH) in the development and doxorubicin (DXR) resistance of OS and the possible mechanistic pathway. METHODS: A quantitative real-time polymerase chain reaction or western blot assays were exploited to analyze the expression of circITCH, miR-524 and Ras association domain family member 6 (RASSF6). Cell viability and half-maximal inhibitory concentration (IC50 ) value of DXR were monitored using a cell counting kit-8 assay. Cell migration, invasion and apoptosis were determined via a transwell assay and flow cytometry. The target interaction among circITCH, miR-524 and RASSF6 was validated by dual-luciferase reporter and RNA immunoprecipitation assays. A xenograft model of MG-63/DXR cells stably expressing circITCH in nude mice was established for assessing the role of circITCH in vivo. RESULTS: Down-regulation of circITCH and RASSF6, as well as the up-regulation of miR-524, was revealed in OS by investigating 40 paired OS tissue and normal tissue samples. Overexpression of circITCH lowered the cell viability, IC50 value of DXR, migration and invasion, whereas it facilitated apoptosis of OS cells. circITCH sponged miR-524 to up-regulate RASSF6, causing OS progression inhibition and DXR resistance reduction. Additionally, circITCH up-regulation reduced tumor growth in vivo. CONCLUSIONS: Transduction with circITCH represses OS progression and promotes DXR sensitivity by the miR-524/RASSF6 axis, providing a new perspective for therapeutic intervention.

TBX15/miR-152/KIF2C pathway regulates breast cancer doxorubicin resistance via promoting PKM2 ubiquitination.

BACKGROUND: Chemoresistance is a critical risk problem for breast cancer treatment. However, mechanisms by which chemoresistance arises remains to be elucidated. The expression of T-box transcription factor 15 (TBX-15) was found downregulated in some cancer tissues. However, role and mechanism of TBX15 in breast cancer chemoresistance is unknown. Here we aimed to identify the effects and mechanisms of TBX15 in doxorubicin resistance in breast cancer. METHODS: As measures of Drug sensitivity analysis, MTT and IC50 assays were used in DOX-resistant breast cancer cells. ECAR and OCR assays were used to analyze the glycolysis level, while Immunoblotting and Immunofluorescence assays were used to analyze the autophagy levels in vitro. By using online prediction software, luciferase reporter assays, co-Immunoprecipitation, Western blotting analysis and experimental animals models, we further elucidated the mechanisms. RESULTS: We found TBX15 expression levels were decreased in Doxorubicin (DOX)-resistant breast cancer cells. Overexpression of TBX15 reversed the DOX resistance by inducing microRNA-152 (miR-152) expression. We found that KIF2C levels were highly expressed in DOX-resistant breast cancer tissues and cells, and KIF2C was a potential target of miR-152. TBX15 and miR-152 overexpression suppressed autophagy and glycolysis in breast cancer cells, while KIF2C overexpression reversed the process. Overexpression of KIF2C increased DOX resistance in cancer cells. Furthermore, KIF2C directly binds with PKM2 for inducing the DOX resistance. KIF2C can prevent the ubiquitination of PKM2 and increase its protein stability. In addition, we further identified that Domain-2 of KIF2C played a major role in the binding with PKM2 and preventing PKM2 ubiquitination, which enhanced DOX resistance by promoting autophagy and glycolysis. CONCLUSIONS: Our data identify a new mechanism by which TBX15 abolishes DOX chemoresistance in breast cancer, and suggest that TBX15/miR-152/KIF2C axis is a novel signaling pathway for mediating DOX resistance in breast cancer through regulating PKM2 ubiquitination and decreasing PKM2 stability. This finding suggests new therapeutic target and/or novel strategy development for cancer treatment to overcome drug resistance in the future.

LncRNA MALAT1 mediates doxorubicin resistance of hepatocellular carcinoma by regulating miR-3129-5p/Nova1 axis.

Drug resistance is one of the major challenges for cancer therapies. In recent years, research on disease-related molecular signaling pathways has become the key ways to understand and overcome obstacles. Dysregulation of MALAT1 could regulate doxorubicin resistance of hepatocellular carcinoma (HCC), but how MALAT1 involving in managing doxorubicin resistance remains unclear yet. We aimed to elucidate the specific molecular mechanism of MALAT1 with doxorubicin resistance in HCC cells. Quantitative real-time polymerase chain reaction (qRT-PCR) was engaged to detect the expression levels of MALAT1, miR-3129-5p and Nova1 mRNA; MTT, western blot, flow cytometry and luciferase reporter assays were executed to identify the influence of MALAT1 on doxorubicin resistance of HCC cells. Xenograft tumor model was created to confirm the biological function of MALAT1 in doxorubicin resistance of HCC cells in vivo. MALAT1 and Nova1 were upregulated, while miR-3129-5p expression was decreased in doxorubicin-resistant HCC tissues and cells. Knockdown of MALAT1 regulated doxorubicin resistance of HCC cells through inhibiting cell proliferation, migration, invasion and promoting apoptosis, but antisense miR-3129-5p released the functional effect of MALAT1 knockdown. Nova1, as a target gene of miR-3129-5p, reversed the results of miR-3129-5p expression and enhanced doxorubicin resistance of HCC cells. Xenograft tumor model suggested that dysregulation of MALAT1 regulated tumor growth and Nova1 to mediate doxorubicin resistance of HCC cells by as a sponge for miR-3129-5p in vivo. Elevation of LncRNA MALAT1 mediated doxorubicin resistance and the progression of HCC via a MALAT1/miR-3129-5p/Nova1 axis. This study would be expected to enrich the understanding of doxorubicin resistance of HCC and provide new ideas for HCC treatment strategies.

Silencing of the CrkL gene reverses the doxorubicin resistance of K562/ADR cells through regulating PI3K/Akt/MRP1 signaling.

BACKGROUND: Doxorubicin is a first-line chemotherapy agent on human myelogenous leukemia clinical treatment, but the development of chemoresistance has largely limited curative effect. In this study, we aimed to evaluate the biological function and molecular mechanisms of CrkL to Doxorubicin resistance. METHODS: Quantitative reverse transcription-PCR (qRT-PCR) assay was performed to examine the expression of CrkL in K562 and K562/ADR cells. The expression of CrkL was silenced through RNA interference technology. MTT assay and flow cytometry were performed to detect the proliferation inhibition and apoptosis rate after CrkL siRNA transfection. The protein expression changes of PI3K/AKT/MRP1 pathway induced by CrkL siRNA were observed by Western Blot assay. Xenograft tumor model was carried out to observe tumor growth in vivo. RESULTS: We observed that silencing of CrkL could effectively increase apoptosis rate induced by doxorubicin and dramatically reversed doxorubicin resistance in K562/ADR cells. Further studies revealed knockdown CrkL expression suppressed PI3K/Akt/MRP1 signaling, which indicated CrkL siRNA reversed doxorubicin effect through regulating PI3K/Akt/MRP1 pathway. In addition, overexpression of MRP1 could evidently reduce apoptosis rate and reversed the inhibitory effects of doxorubicin resistance caused by CrkL siRNA on K562/ADR cells. Finally, in vivo experiments revealed that CrkL silencing acted a tumor-suppressing role in myelogenous leukemia via regulating PI3K/Akt/MRP1 signaling. CONCLUSION: Together, we indicated that CrkL is up-regulated in myelogenous leukemia cells and silencing of CrkL could reverse Doxorubicin resistance effectively. These results show a potential novel strategy for intervention chemoresistance in myelogenous leukemia during chemotherapy.

MiR-194-5p enhances the sensitivity of nonsmall-cell lung cancer to doxorubicin through targeted inhibition of hypoxia-inducible factor-1.

BACKGROUND: Despite chemotherapy being a common treatment, an increase in chemoresistance over time is unavoidable. We therefore investigated the role of miR-194-5p in regulating chordoma cell behavior and examined the downstream effectors of miR-194-5p. METHODS: In this study, NSCLC cell lines A549 and H460 were cultured under hypoxic conditions for 1 week to induce drug resistance to doxorubicin (DOX). The connection between miR-194-5p and HIF-1 was revealed by reverse transcription and real-time polymerase chain reaction (RT-qPCR), western blot, and dual-luciferase assays. We used TUNEL staining and the CCK-8 test to assess the sensitivity of NSCLC cells to DOX. RESULTS: We found that hypoxia-induced NSCLC cells enhanced resistance to DOX. MiR-194-5p was substantially reduced, and HIF-1 was increased in hypoxia-induced drug-resistant NSCLC cells. Moreover, miR-194-5p successfully induced NSCLC cell apoptosis by directly inhibiting HIF-1, thereby enhancing DOX sensitivity. CONCLUSIONS: MiR-194-5p enhanced the sensitivity of NSCLC cells to DOX by directly inhibiting HIF-1. This work provides insights into underlying treatments for drug-resistant NSCLC.

Cell-Penetrating Doxorubicin Released from Elastin-Like Polypeptide Kills Doxorubicin-Resistant Cancer Cells in In Vitro Study.

Elastin-like polypeptides (ELPs) undergo a characteristic phase transition in response to ambient temperature. Therefore, it has been be used as a thermosensitive vector for the delivery of chemotherapy agents since it can be used to target hyperthermic tumors. This novel strategy introduces unprecedented options for treating cancer with fewer concerns about side effects. In this study, the ELP system was further modified with an enzyme-cleavable linker in order to release drugs within tumors. This system consists of an ELP, a matrix metalloproteinase (MMP) substrate, a cell-penetrating peptide (CPP), and a 6-maleimidocaproyl amide derivative of doxorubicin (Dox). This strategy shows up to a 4-fold increase in cell penetration and results in more death in breast cancer cells compared to ELP-Dox. Even in doxorubicin-resistant cells (NCI/ADR and MES-SA/Dx5), ELP-released cell-penetrating doxorubicin demonstrated better membrane penetration, leading to at least twice the killing of resistant cells compared to ELP-Dox and free Dox. MMP-digested CPP-Dox showed better membrane penetration and induced more cancer cell death in vitro. This CPP-complexed Dox released from the ELP killed even Dox-resistant cells more efficiently than both free doxorubicin and non-cleaved ELP-CPP-Dox.

Exosome-mediated transfer of long noncoding RNA H19 induces doxorubicin resistance in breast cancer.

Development of the acquired resistance is one major obstacle during chemotherapy for cancer patients. Exosomes mediate intercellular communication and cause environmental changes in tumor progression by transmitting active molecules. In this study, the role of long noncoding RNA H19 within exosomes is elucidated in terms of regulating doxorubicin (DOX) resistance of breast cancer. As a result, increased H19 expression was observed in DOX-resistant breast cancer cells in comparison with the corresponding parental cells. Suppression of H19 significantly lowered DOX resistance by decreasing cell viability, lowering colony-forming ability, and inducing apoptosis. Moreover, extracellular H19 could be moved to sensitive cells via being incorporated into exosomes. Treating sensitive cells with exosomes from resistant cells increased the chemoresistance of DOX, while downregulation of H19 in sensitive cells abated this effect. Taken together, H19 could be delivered by exosomes to sensitive cells, leading to the dissemination of DOX resistance. Our finding highlights the potential of exosomal H19 as a molecular target to reduce DOX resistance.

LncRNA XIST promotes chemoresistance of breast cancer cells to doxorubicin by sponging miR-200c-3p to upregulate ANLN.

The resistance of breast cancer cells to drugs is a major obstacle to effective cancer chemotherapy. Here, we study the function mechanisms of long non-coding RNA XIST in chemoresistance of breast cancer to doxorubicin. We examined the 50% inhibitive concentration of doxorubicin to MDA-MB-231 and MDA-MB-231/ADM cells, showing that the doxorubicin resistance of MDA-MB-231/ADM cells was much higher than MDA-MB-231 cells. The gene or protein expression of XIST and ANLN were also higher in MDA-MB-231/ADM cells than that in MDA-MB-231 cells. Moreover, XIST overexpression promoted cell proliferation and inhibited apoptosis of doxorubicin-treated MDA-MB-231 cells by promoting ANLN expression. XIST silencing inhibited cell proliferation and promoted apoptosis of doxorubicin-treated MDA-MB-231/ADM cells by inhibiting ANLN expression. Luciferase reporter assay showed that XIST functioned as a competing endogenous RNA to repress miR-200c-3p, which controlled its downstream target ANLN. In conclusion, these data reveal that XIST promotes chemoresistance of breast cancer cells to doxorubicin by sponging miR-200c-3p to upregulate ANLN. This work explores the relationship between lncRNA XIST and doxorubicin resistance in breast cancer cells and highlights a novel therapeutic target for the treatment of breast cancer.

Hyperthermia Induced by Gold Nanoparticles and Visible Light Photothermy Combined with Chemotherapy to Tackle Doxorubicin Sensitive and Resistant Colorectal Tumor 3D Spheroids.

Current cancer therapies are frequently ineffective and associated with severe side effects and with acquired cancer drug resistance. The development of effective therapies has been hampered by poor correlations between pre-clinical and clinical outcomes. Cancer cell-derived spheroids are three-dimensional (3D) structures that mimic layers of tumors in terms of oxygen and nutrient and drug resistance gradients. Gold nanoparticles (AuNP) are promising therapeutic agents which permit diminishing the emergence of secondary effects and increase therapeutic efficacy. In this work, 3D spheroids of Doxorubicin (Dox)-sensitive and -resistant colorectal carcinoma cell lines (HCT116 and HCT116-DoxR, respectively) were used to infer the potential of the combination of chemotherapy and Au-nanoparticle photothermy in the visible (green laser of 532 nm) to tackle drug resistance in cancer cells. Cell viability analysis of 3D tumor spheroids suggested that AuNPs induce cell death in the deeper layers of spheroids, further potentiated by laser irradiation. The penetration of Dox and earlier spheroid disaggregation is potentiated in combinatorial therapy with Dox, AuNP functionalized with polyethylene glycol (AuNP@PEG) and irradiation. The time point of Dox administration and irradiation showed to be important for spheroids destabilization. In HCT116-sensitive spheroids, pre-irradiation induced earlier disintegration of the 3D structure, while in HCT116 Dox-resistant spheroids, the loss of spheroid stability occurred almost instantly in post-irradiated spheroids, even with lower Dox concentrations. These results point towards the application of new strategies for cancer therapeutics, reducing side effects and resistance acquisition.

CCL20 Promotes Ovarian Cancer Chemotherapy Resistance by Regulating ABCB1 Expression.

Ovarian cancer (OC) is one of prevalent tumors and this study aimed to explore CCL20's effects on doxorubicin resistance of OC and related mechanisms. Doxorubicin-resistant SKOV3 DR cells were established from SKOV3 cells via 6-month continuous exposure to gradient concentrations of doxorubicin. Quantitative PCR and Western blot assay showed that SKOV3 DR cells had higher level of CCL20 than SKOV3 cells, and doxorubicin upregulated CCL20 expression in SKOV3 cells. MTT and cell count assay found that CCL20 overexpression plasmid enhanced doxorubicin resistance of SKOV3 and OVCA433 cells compared to empty vector, as shown by the increase in cell viability. In contrast, CCL20 shRNA enhanced doxorubicin sensitivity of SKOV3 DR cells compared to control. CCL20 overexpression plasmid promoted NF-kB activation and positively regulated ABCB1 expression. Besides, ABCB1 overexpression plasmid enhanced the viability of SKOV3 and OVCA433 cells compared to empty vector under treatment with the same concentration of doxorubicin, whereas ABCB1 shRNA inhibited doxorubicin resistance of SKOV3 DR cells compared to control. In conclusion, CCL20 enhanced doxorubicin resistance of OC cells by regulating ABCB1 expression.Key words: CCL20, ovarian cancer, doxorubicin resistance, tumor-promoting, ABCB1.

Polydatin inhibits proliferation and promotes apoptosis of doxorubicin-resistant osteosarcoma through LncRNA TUG1 mediated suppression of Akt signaling.

BACKGROUND: Development of doxorubicin-resistance is the main difficulty for osteosarcoma treatment. LncRNA Taurine upregulated gene 1 (TUG1) has been identified as oncogenic lncRNA in different types of carcinomas and was involved in chemoresistance. We aim to evaluate the anti-proliferative effects and the underlying molecular mechanism of Polydatin in doxorubicin-resistant osteosarcoma. METHODS: Doxorubicin-resistant osteosarcoma cell lines were established. MTT, colony formation, apoptosis assay, qRT-PCR and Western blotting analysis, immunohistochemistry and animal study were carried out. RESULTS: It has been showed Polydatin (50-250 µM) inhibited the cell proliferation in a dose- and time-dependent manner at 24 h, 48 h, and 72 h. Polydatin promoted the cell apoptosis significantly with the highest apoptosis rate >50%. Polydatin down-regulated TUG1 expression and TUG1/Akt signaling suppression was involved in Polydatin treated doxorubicin-resistant osteosarcoma cells. The in vivo study further confirmed the anti-cancer effect of Polydatin and related mechanisms. CONCLUSIONS: Polydatin may be a novel therapeutic agent for doxorubicin-resistant osteosarcoma treatment and TUG1 would be a potential molecular target.

Tumor Cell Behavior in Porous Hydrogels: Effect of Application Technique and Doxorubicin Treatment.

The effect of porosity on diffusion characteristics of scaffolds and invasive capacity of MCF-7 and PC-3 tumor cells was studied for gelatin hydrogels. According to MTS test results, the efficiency of population of a macroporous cryogel by cells applied by different techniques increased in the following order: migration from the monolayer

PRMT5 determines the sensitivity to chemotherapeutics by governing stemness in breast cancer.

PURPOSE: Acquired resistance to chemotherapeutic agents in breast cancer is a major clinical challenge. Recent studies have shown that the emergence of cancer stem cells contributes to the development of drug resistance, and the protein arginine methyltransferase 5 (PRMT5) was crucial for the maintenance of stemness. However, the roles of PRMT5 in breast cancer cell stemness and the development of cancer drug resistance have not been clarified. In this study, we investigated the effect of PRMT5 on the sensitivity to doxorubicin and cell stemness in breast cancer. METHODS: PRMT5 expression was assessed in a panel of breast cancer cell lines (MDA-MB-231, MCF7, T-47D, BT-474, Au-565) and normal mammal epithelial cells (MCF10A). For knockdown of PRMT5 expression, two pairs of shRNAs as well as a control shRNA were utilized. Meanwhile, the wild-type PRMT5 and its catalytically dead counterpart (R368A) were stably overexpressed in MDA-MB-231 and MCF7 cells. The sensitivity to doxorubicin was determined by MTT assays, TUNEL assays, and Western blot analyses. To evaluate the degree of cell stemness, CD24/CD44-sorting and mammosphere formation experiments were performed. RESULTS: We demonstrated that PRMT5 regulates OCT4/A, KLF4, and C-MYC in breast cancer to govern stemness and affects the doxorubicin resistance of breast cancer. CONCLUSION: Our study suggests that PRMT5 may play an important role in the doxorubicin resistance of breast cancer.