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Chemotherapy typically involves the use of specific chemodrugs to inhibit the proliferation of cancer cells, but the frequent emergence of a variety of multidrug‐resistant cancer cells poses a tremendous threat to our combat against cancer. The fundamental causes of multidrug resistance (MDR) have been studied for decades, and can be generally classified into two types: one is associated with the activation of diverse drug efflux pumps, which are responsible for translocating intracellular drug molecules out of the cells; the other is linked with some non‐efflux pump‐related mechanisms, such as antiapoptotic defense, enhanced DNA repair ability, and powerful antioxidant systems. To overcome MDR, intense efforts have been made to develop synergistic therapeutic strategies by introducing MDR inhibitors or combining chemotherapy with other therapeutic modalities, such as phototherapy, gene therapy, and gas therapy, in the hope that the drug‐resistant cells can be sensitized toward chemotherapeutics. In particular, nanotechnology‐based drug delivery platforms have shown the potential to integrate multiple therapeutic agents into one system. In this review, the focus was on the recent development of nanostrategies aiming to enhance the efficiency of chemotherapy and overcome the MDR of cancer in a synergistic manner. Different combinatorial strategies are introduced in detail and the advantages as well as underlying mechanisms of why these strategies can counteract MDR are discussed. This review is expected to shed new light on the design of advanced nanomedicines from the angle of materials and to deepen our understanding of MDR for the development of more effective anticancer strategies. This article is categorized under:Nanotechnology Approaches to Biology > Nanoscale Systems in BiologyTherapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease [ABSTRACT FROM AUTHOR]

Ovarian cancer is the most common type of gynecologic cancer. One of the leading causes of high mortality is chemoresistance, developed primarily or during treatment. Different mechanisms of drug resistance appear at the cellular and cancer tissue organization levels. We examined the differences in response to the cytotoxic drugs CIS, MTX, DOX, VIN, PAC, and TOP using 2D (two-dimensional) and 3D (three-dimensional) culture methods. We tested the drug-sensitive ovarian cancer cell line W1 and established resistant cell lines to appropriate cytotoxic drugs. The following qualitative and quantitative methods were used to assess: 1) morphology - inverted microscope and hematoxylin & eosin staining; 2) viability - MTT assay; 3) gene expression – a quantitative polymerase chain reaction; 4) identification of proteins – immunohistochemistry, and immunofluorescence. Our results indicate that the drug-sensitive and drug-resistant cells cultured in 3D conditions exhibit stronger resistance than the cells cultured in 2D conditions. A traditional 2D model shows that drug resistance of cancer cells is caused mainly by changes in the expression of genes encoding ATP-binding cassette transporter proteins, components of the extracellular matrix, "new" established genes related to drug resistance in ovarian cancer cell lines, and universal marker of cancer stem cells. Whereas in a 3D model, the drug resistance in spheroids can be related to other mechanisms such as the structure of the spheroid (dense or loose), the cell type (necrotic, quiescent, proliferating cells), drug concentrations or drug diffusion into the dense cellular/ECM structure. [Display omitted] • The resistance to cytotoxic drugs was examined using different cell culture models. • Compared to cells cultured in monolayers, spheroids are more resistant. • Changes in gene expression are the main reason monolayers become drug resistant. • In the development of drug resistance, spheroids exhibit tissue-specific mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: Personalized oncology significantly relies on the development of theranostic agents to integrate cancer therapeutics and diagnostics. Current strategy for development of such multifunctional agents requires multistep chemical conjugation with cancer specific ligands, contrast agents and therapeutic drugs. In this study, we reported a near infrared (NIR) heptamethine indocyanine dye, IR-780, which selectively accumulated in the mitochondria of drug-resistant human lung cancer cells (A549/DR) and significantly inhibited cell growth, self-renewal and migration without the need of any chemical conjugation. IR-780 was also able to induce A549/DR cell apoptosis by disrupting the mitochondrial function. Furthermore, IR-780 dye exhibited remarkable tumoricidal activity and inhibited tumor recurrence in mouse syngeneic Lewis lung carcinoma xenograft model. With the unique properties of targeting, near infrared imaging and inhibitive effect to the drug-resistant cancer cells both in vitro and in vivo, IR-780 may represent a potential theranostic agent for tumor recurrence. [Copyright &y& Elsevier]

A 10- O -deacetylbaccatin III 10- O -acetyltransferase biocatalyst from Taxus plants was expressed in bacteria whole-cells that were fed 10- O -deacetylbaccatin III and cyclopropane carboxylic acid. Product analysis by qualitative LC/ESI-MS suggested that the C10-acylated products baccatin III, 10- O - n -propionyl-10- O -deacetylbaccatin III, and 10- O -cyclopropanecarbonyl-10- O -deacetylbaccatin III were made in vivo. The results implied that the cells provided non-natural cyclopropanecarbonyl CoA, from a broad-specificity CoA ligase, and natural products, acetyl CoA and n -propionyl CoA, from reserves in the bacteria for use by acyltransferase to acylate 10- O -deacetylbaccatin III in vivo. The 10-acyl-10- O -deacetylbaccatin III are precursors used to synthesize new-generation paclitaxel analogs SB-T-1214 and SB-T-121303, which are effective against cancer cells resistant to paclitaxel and its drug derivatives. The k cat and K M of the acyltransferase for cyclopropanecarbonyl CoA (0.83 s−1, 0.15 M) and n -propionyl CoA (1.2 s−1, 0.15 M) guided scale-up efforts. The 10-acyl-10- O -deacetylbaccatin III analogs (∼45 mg each) were made in vitro by the acyltransferase when incubated with the commercial taxane 10- O -deacetylbaccatin III and synthesized cyclopropanecarbonyl or n -propionyl CoA. The structures of the 10-acyl products were verified by NMR analyses that confirmed C10 acylation of the taxane substrate. LC/ESI-MS/MS analysis also supported the identities of the biocatalyzed products. This effort provides a biocatalysis framework to produce new-generation taxane precursors. [Display omitted] • Whole-cell biocatalysis to make a non-natural taxane analog via a non-natural acyl CoA. • In vitro biocatalytic production of new-generation paclitaxel precursors at mg-scale. • Demonstrated the flexibility of a short-chain n -alkanoyltransferase for cyclopropanecarbonyl. [ABSTRACT FROM AUTHOR]

Irinotecan (IRI), a topoisomerase I inhibitor blocking DNA synthesis, is a widely used chemotherapy drug for metastatic colorectal cancer. Despite being an effective chemotherapy drug, its clinical effectiveness is limited by both intrinsic and acquired drug resistance. Previous studies indicate IRI induces cancer stemness in irinotecan-resistant (IRI-resistant) cells. Metformin, an oral antidiabetic drug, was recently reported for anticancer effects, likely due to its selective killing of cancer stem cells (CSCs). Given IRI-resistant cells exhibiting high cancer stemness, we hypothesize metformin can sensitize IRI-resistant cells and rescue the therapeutic effect. In this work, we utilized the Single-probe mass spectrometry technique to analyze live IRI-resistant cells under different treatment conditions. We discovered that metformin treatment was associated with the downregulation of lipids and fatty acids, potentially through the inhibition of fatty acid synthase (FASN). Importantly, certain species can be only detected from cells in their living status. The level of synergistic effect of metformin and IRI in their co-treatment of IRI-resistant cells was evaluated using Chou-Talalay combinational index. Using enzymatic activity assay, we determined that the co-treatment exhibit the highest FASN inhibition compared with the mono-treatment of IRI or metformin. To our knowledge, this is the first single-cell MS metabolomics study demonstrating metformin-IRI synergistic effect overcoming drug resistance in IRI-resistant cells. [Display omitted] • Ambient single cell mass spectrometry was used to study live cells. • Other analytical techniques (e.g., cytotoxicity assay, enzymatic activity assay, and HPLC/MS) were used to provide complementary information. • Drug-resistant cancer cells' viabilities and molecular profiles were affected by antidiabetic drug metformin. • Unique lipids and metabolites were observed only in live single cells. • Inhibition of fatty acid synthase (FASN) is a potential mechanism related to metformin treatment of drug-resistant cancer cells. [ABSTRACT FROM AUTHOR]

Chemotherapy typically involves the use of specific chemodrugs to inhibit the proliferation of cancer cells, but the frequent emergence of a variety of multidrug-resistant cancer cells poses a tremendous threat to our combat against cancer. The fundamental causes of multidrug resistance (MDR) have been studied for decades, and can be generally classified into two types: one is associated with the activation of diverse drug efflux pumps, which are responsible for translocating intracellular drug molecules out of the cells; the other is linked with some non-efflux pump-related mechanisms, such as antiapoptotic defense, enhanced DNA repair ability, and powerful antioxidant systems. To overcome MDR, intense efforts have been made to develop synergistic therapeutic strategies by introducing MDR inhibitors or combining chemotherapy with other therapeutic modalities, such as phototherapy, gene therapy, and gas therapy, in the hope that the drug-resistant cells can be sensitized toward chemotherapeutics. In particular, nanotechnology-based drug delivery platforms have shown the potential to integrate multiple therapeutic agents into one system. In this review, the focus was on the recent development of nanostrategies aiming to enhance the efficiency of chemotherapy and overcome the MDR of cancer in a synergistic manner. Different combinatorial strategies are introduced in detail and the advantages as well as underlying mechanisms of why these strategies can counteract MDR are discussed. This review is expected to shed new light on the design of advanced nanomedicines from the angle of materials and to deepen our understanding of MDR for the development of more effective anticancer strategies. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease., (© 2021 Wiley Periodicals LLC.)

Microtubule-targeting agents (MTA) have enjoyed significant clinical success for decades. However, several mechanisms may cause inactivation of such drugs, leading to acquired resistance in patients treated with them. Therefore, drugs containing a stilbene-like skeleton and possessing dual inhibitory activity may provide a new and differentiated treatment for patients to overcome challenging acquired resistance. A new compound (16c) displays promising anticancer activity with GI 50 of 22 ± 2 and 12 ± 0.1 nM in vincristine-resistant nasopharyngeal (KB-Vin) cancer cells and etoposide-resistant nasopharyngeal (KB-7D) cancer cells and is better than vincristine, etoposide, ABT-751, and MS-275. A mechanistic study revealed that 16c interferes with the cell cycle distribution and induces cell cycle arrest at the G2/M phase and severe mitotic spindle defects followed by apoptosis. In addition, it produces much more significant cytotoxicity than vincristine and etoposide in the corresponding resistant cells, indicating that it may be a promising candidate to overcome drug resistance in cancer cells. Compound 16c also displays inhibitory activity against HDAC 1 and HDAC 2 with IC 50 values of 1.07 μM, and 1.47 μM, respectively. These findings may lead to a new type of structural motif for future development of drugs that could overcome acquired resistance to MTAs. Image 1 • N-phenyl-4-(2-phenylsulfonamido)-benzamides act as Microtubule-targeting agents. • 16c displays promising anticancer activity against resistant cancer cells. • 16c induces cell cycle arrest at the G2/M phase. • 16c significantly inhibits microtubule polymerization. • 16c exhibited inhibitory potential against HDAC 1, 2 and 3. [ABSTRACT FROM AUTHOR]