Chemosensitizing Activity Research Articles

Anti-cancer activity of capsaicin and its analogs in gynecological cancers.

Capsaicin is the hot and pungent ingredient of chili peppers. It is a potent pain-relieving agent and is often present in over-the-counter analgesic lotions and creams. Several convergent studies reveal that capsaicin displays growth-suppressive activity in human cancers in vitro and in vivo. Apart from its growth-suppressive activity (as a single agent), capsaicin has been found to sensitize human cancer cells to the pro-apoptotic effects of chemotherapy and radiation. The first part of this book chapter discusses the anti-cancer activity of capsaicin in gynecological cancers in cell culture experiments and mouse models. Out of all gynecological cancers, the anti-cancer activity of capsaicin (and its analogs) has only been investigated in cervical cancers and ovarian cancers. The clinical development of capsaicin as a viable anti-cancer drug has remained challenging due to its poor bioavailability and aqueous solubility properties. In addition, the administration of capsaicin is associated with adverse side effects like gastrointestinal cramps, stomach pain, irritation in the gut, nausea diarrhea and vomiting. Two strategies have been investigated to overcome these drawbacks of capsaicin. The first is to encapsulate capsaicin in sustained release drug delivery systems. The second strategy is to design non-pungent capsaicin analogs which will retain the anti-tumor activity of capsaicin. The second part of this chapter provides an overview of the anti-neoplastic (and chemosensitization activity) of capsaicin analogs and capsaicin-based sustained release formulations in cervical and ovarian cancers. The design of selective non-pungent capsaicin analogs and capsaicin-based polymeric drug delivery systems may foster the hope of novel strategies for the treatment and management of gynecological cancers.

Polyporenic Acids from the Mushroom Buglossoporus quercinus Possess Chemosensitizing and Efflux Pump Inhibitory Activities on Colo 320 Adenocarcinoma Cells.

Polyporenic acids N-R (1-5), five novel 24-methylene lanostane triterpenes along with seven known polyporenic acids (6-12), were identified from the fruiting bodies of Buglossoporus quercinus. The isolation of compounds 1-12 was performed by a combination of multistep flash chromatography and reversed-phase high-performance liquid chromatography (HPLC). The structure determination was carried out by extensive spectroscopic analysis, including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) experiments. The isolated fungal metabolites were investigated for their antiproliferative activity in vitro by 3-(4,5-dimethylthiazol2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on the resistant Colo 320 human colon adenocarcinoma cell line expressing P-glycoprotein (ABCB1). The lanostane triterpenes exerted moderate antiproliferative activity with IC50 values in the range of 20.7-106.2 μM. A P-glycoprotein efflux pump modulatory test on resistant Colo 320 cells highlighted that fungal metabolites 3, 5, 8, and 10-12 have the ability to inhibit the efflux pump activity of cancer cells. Moreover, the drug interactions of triterpenes with doxorubicin were studied by the checkerboard method. Compounds 3-4, and 7-12 interacted in a synergistic manner, while an outstanding potency was detected for compound 9, which was defined as strong synergism (CI = 0.276). The current study reveals that B. quercinus is a remarkable source of fungal steroids with considerable chemosensitizing activity on cancer cells.

Type I interferon signaling in malignant blasts contributes to treatment efficacy in AML patients

While type I interferon (IFN) is best known for its key role against viral infection, accumulating preclinical and clinical data indicate that robust type I IFN production in the tumor microenvironment promotes cancer immunosurveillance and contributes to the efficacy of various antineoplastic agents, notably immunogenic cell death inducers. Here, we report that malignant blasts from patients with acute myeloid leukemia (AML) release type I IFN via a Toll-like receptor 3 (TLR3)-dependent mechanism that is not driven by treatment. While in these patients the ability of type I IFN to stimulate anticancer immune responses was abolished by immunosuppressive mechanisms elicited by malignant blasts, type I IFN turned out to exert direct cytostatic, cytotoxic and chemosensitizing activity in primary AML blasts, leukemic stem cells from AML patients and AML xenograft models. Finally, a genetic signature of type I IFN signaling was found to have independent prognostic value on relapse-free survival and overall survival in a cohort of 132 AML patients. These findings delineate a clinically relevant, therapeutically actionable and prognostically informative mechanism through which type I IFN mediates beneficial effects in patients with AML.

Identification of chemosensitizing agents of colorectal cancer in Rauvolfia vomitoria using an NMR-based chemometric approach.

Searching for new adjuvants of conventional chemotherapeutic approaches against colorectal cancer cells is extremely urgent. In current research, a non-targeted analytical approach was established by combining proton nuclear magnetic resonance spectroscopy with a chemometrics data mining tool to identify chemosensitizing agents from Rauvolfia vomitoria. This approach enabled the identification of potential active constituents in the initial fractionation process and provided their structural information. This strategy was validated by its application to Rauvolfia vomitoria extract exhibiting chemosensitizing activity on 5-fluorouracil against colorectal cancer cells. After the workflow, the biochemometrics analysis showed that at least 15 signals (Variable influence on projection (VIP) > 1) could have contributions in the differentiation of various fractions. Through systematic literature and database searches, we found that the most active fraction (fraction 7) exhibited the highest presence of sabazin-type and armaniline-type alkaloids, which were potential chemosensitizers as previously reported. To validate the results of the strategy, the effect of 5-FU and compounds isolated from fraction seven incubation on HCT-8 and LoVo cell vialibilty were evaluated. These results evidenced that compound β-carboline (3), 1-methyl-β-carboline (4), and lochnerine (6) could enhance the cytotoxicity of 5-fluorouracil against to Colorectal cancer cells. Besides, 21 compounds including two new compounds were isolated from Rauvolfia vomitoria. The experimental results verify the reliability of the method, and this approach provides a new and efficient tool to overcome some of the bottlenecks in natural products drug discovery.

Anticancer and chemosensitizing activities of stilbenoids from three orchid species.

Recently, we have isolated and identified several bioactive flavonoids and stilbenoids with potential anticancer activity from Thai orchids. In this study, we further investigated the cytotoxic and chemosensitizing activities of these phytochemicals (namely, pinocembrin, cardamonin, isalpinin, galangin, pinosylvin monomethyl ether, 2,3'-dihydroxy-5'-methoxystilbene, (E)-2,5'-dihydroxy-2'-(4-hydroxybenzyl)-3'-methoxystilbene, 2,3-dihydroxy-3',5'-dimethoxystilbene, 2,3'-dihydroxy-5,5'-dimethoxystilbene, 3,4'-dihydroxy-5-methoxystilbene and batatasin III) against breast cancer MCF7 cells and its two multidrug resistant (MDR) sublines (MCF7/DOX and MCF7/MX). Cytotoxicity was determined with MTT assay for the estimation of the half maximal cytotoxic concentrations (IC50). Effects of the test compounds on activities of efflux transporters (BCRP, P-gp, MRP1, and MRP2) were evaluated with substrate accumulation assays using fluorometry and flow cytometry analysis. Out of these 11 test compounds, the stilbene pinosylvin monomethyl ether displayed its cytotoxicity specifically toward MCF7 cells (IC50 = 6.2 ± 1.2μM, 72-h incubation) with 4.96 folds higher than normal fibroblast. Its potency decreased in MCF7/DOX and MCF7/MX cells by 3.94 and 7.38 folds, respectively. Our transporter assay indicated that this stilbene significantly reduced the activities of P-gp, MRP1, and MRP2, but not BCRP. After 48-h co-incubation, this stilbene (at 2μM) synergistically increased doxorubicin- and mitoxantrone-mediated cytotoxicity in MCF7, MCF7/DOX, and MCF7/MX cells potentially by increasing the intracellular level of cytotoxic drug. Pinosylvin monomethyl ether could sensitize breast cancer cells to chemotherapy and overcome MDR, in part, via the inhibition of drug efflux transporters.

Triterpenes from Pholiota populnea as Cytotoxic Agents and Chemosensitizers to Overcome Multidrug Resistance of Cancer Cells.

The detailed mycochemical analysis of the n-hexane extract of Pholiota populnea led to the isolation of four new lanostane diesters, named pholiols A–D (1–4), together with an acyclic triterpene, (3S,6E,10E,14E,18E,22S)-2,3,22,23-tetrahydroxy-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene (5), ergosterol (6), and 3β-hydroxyergosta-7,22-diene (7). The isolation was carried out by multistep flash chromatography, and the structures were elucidated using extensive spectroscopic analyses, including 1D and 2D NMR and MS measurements. The isolated metabolites (1–6) were investigated for cytotoxic activity against Colo205 and Colo320 colon adenocarcinoma and nontumoral MRC-5 cell lines. Among the tested compounds, ergosterol (6) showed substantial cytotoxic activity against all cell lines with IC50 values of 4.9 μM (Colo 205), 6.5 μM (Colo 320), and 0.50 μM (MRC) with no tumor cell selectivity. A P-glycoprotein efflux pump modulatory test on resistant Colo320 cells revealed that pholiols A (1) and B (2) and linear triterpene polyol 5 have the capacity to inhibit the efflux-pump overexpressed in the cells. Moreover, the drug interactions of triterpenes with doxorubicin were studied by the checkerboard method on Colo 320 cells. Pholiols B (2) and D (4) interacted in synergistic and acyclic triterpene 5 in a very strong synergistic manner; the combination index (CI) values at 50% of the growth inhibition dose (ED50) were found to be 0.348, 0.660, and 0.082, respectively. Our results indicate that P. populnea is a promising source for finding new triterpenes with significant chemosensitizing activity on cancer cells.

Curcumin as an Enhancer of Therapeutic Efficiency of Chemotherapy Drugs in Breast Cancer.

Female breast cancer is the world’s most prevalent cancer in 2020. Chemotherapy still remains a backbone in breast cancer therapy and is crucial in advanced and metastatic breast cancer treatment. The clinical efficiency of chemotherapy regimens is limited due to tumor heterogeneity, chemoresistance, and side effects. Chemotherapeutic drug combinations with natural products hold great promise for enhancing their anticancer efficacy. Curcumin is an ideal chemopreventive and chemotherapy agent owning to its multitargeting function on various regulatory molecules, key signaling pathways, and pharmacological safety. This review aimed to elucidate the potential role of curcumin in enhancing the efficacy of doxorubicin, paclitaxel, 5-fluorouracil, and cisplatin via combinational therapy. Additionally, the molecular mechanisms underlying the chemosensitizing activity of these combinations have been addressed. Overall, based on the promising therapeutic potential of curcumin in combination with conventional chemotherapy drugs, curcumin is of considerable value to develop as an adjunct for combination chemotherapy with current drugs to treat breast cancer. Furthermore, this topic may provide the frameworks for the future research direction of curcumin–chemotherapy combination studies and may benefit in the development of a novel therapeutic strategy to maximize the clinical efficacy of anticancer drugs while minimizing their side effects in the future breast cancer treatment.

Veliparib for the treatment of solid malignancies.

Veliparib is a poly adenosine diphosphate ribose polymerase (PARP) -1 and -2 inhibitor with chemo-sensitizing and anticancer activities that has shown promising results in early-phase trials. The aim of this comprehensive review is to summarise the profile of veliparib and to provide an overview of its early clinical investigations. Details of all the completed trials evaluating the profile of veliparib were identified from ClinicalTrials.gov with the relevant keywords. Furthermore, databases such as Google Scholar and PubMed were searched using the National Clinical Trial (NCT) number to retrieve publications of results not listed in the trial registry. A total of 25 completed clinical trials indicating the use of veliparib in solid malignancies were identified. The results showed that veliparib is well tolerated, both as a single agent and in combination with standard chemotherapy doses. Being a broad-spectrum potentiator of DNA-damaging agents and radiation, it has shown to improve the clinical outcomes, particularly in solid tumors like ovarian cancer, breast cancer and lung cancer. The results from clinical trials indicate that veliparib can be an excellent therapeutic strategy for BRCA mutation associated cancers and tumors bearing deficiencies in the HR pathway as well. Further studies establishing the dosing, sequence of therapy, extended use and compatibility with various anti-cancer drugs are warranted to define its exact role in cancer therapy.

MiR-99b-5p, miR-380-3p, and miR-485-3p are novel chemosensitizing miRNAs in high-risk neuroblastoma

Neuroblastoma is a deadly childhood cancer arising in the developing sympathetic nervous system. High-risk patients are currently treated with intensive chemotherapy, which is curative in only 50% of children and leaves some surviving patients with life-long side effects. microRNAs (miRNAs) are critical regulators of neural crest development and are deregulated during neuroblastoma tumorigenesis, making miRNA-based drugs an attractive therapeutic avenue. A functional screen of >1,200 miRNA mimics was conducted in neuroblastoma cell lines to discover miRNAs that sensitized cells to low doses (30% inhibitory concentration [IC30]) of doxorubicin and vincristine chemotherapy used in the treatment of the disease. Three miRNAs, miR-99b-5p, miR-380-3p, and miR-485-3p, had potent chemosensitizing activity with doxorubicin in multiple models of high-risk neuroblastoma. These miRNAs underwent genomic loss in a subset of neuroblastoma patients, and low expression predicted poor survival outcome. Invitro functional assays revealed each of these miRNAs enhanced the anti-proliferative and pro-apoptotic effects of doxorubicin. We used RNA sequencing (RNA-seq) to show that miR-99b-5p represses neuroblastoma dependency genes LIN28B and PHOX2B both invitro and in patient-derived xenograft (PDX) tumors. Luciferase reporter assays demonstrate that PHOX2B is a direct target of miR-99b-5p. We anticipate that restoring the function of the tumor-suppressive miRNAs discovered here may be a valuable therapeutic strategy for the treatment of neuroblastoma patients.

Autophagy Blockade by Ai Du Qing Formula Promotes Chemosensitivity of Breast Cancer Stem Cells Via GRP78/β-Catenin/ABCG2 Axis.

Accumulating evidence suggests that the root of drug chemoresistance in breast cancer is tightly associated with subpopulations of cancer stem cells (CSCs), whose activation is largely dependent on taxol-promoting autophagy. Our pilot study identified GRP78 as a specific marker for chemoresistance potential of breast CSCs by regulating Wnt/β-catenin signaling. Ai Du Qing (ADQ) is a traditional Chinese medicine formula that has been utilized in the treatment cancer, particularly during the consolidation phase. In the present study, we investigated the regulatory effects and molecular mechanisms of ADQ in promoting autophagy-related breast cancer chemosensitivity. ADQ with taxol decreasing the cell proliferation and colony formation of breast cancer cells, which was accompanied by suppressed breast CSC ratio, limited self-renewal capability, as well as attenuated multi-differentiation. Furthermore, autophagy in ADQ-treated breast CSCs was blocked by taxol via regulation of β-catenin/ABCG2 signaling. We also validated that autophagy suppression and chemosensitizing activity of this formula was GRP78-dependent. In addition, GRP78 overexpression promoted autophagy-inducing chemoresistance in breast cancer cells by stabilizing β-catenin, while ADQ treatment downregulated GRP78, activated the Akt/GSK3β-mediated proteasome degradation of β-catenin via ubiquitination activation, and consequently attenuated the chemoresistance-promoted effect of GRP78. In addition, both mouse breast cancer xenograft and zebrafish xenotransplantation models demonstrated that ADQ inhibited mammary tumor growth, and the breast CSC subpopulation showed obscure adverse effects. Collectively, this study not only reveals the chemosensitizating mechanism of ADQ in breast CSCs, but also highlights the importance of GRP78 in mediating autophagy-promoting drug resistance via β-catenin/ABCG2 signaling.

Studying the Ability of Thymol to Improve Fungicidal Effects of Tebuconazole and Difenoconazole Against Some Plant Pathogenic Fungi in Seed or Foliar Treatments.

Thymol, a secondary plant metabolite possessing antifungal and chemosensitizing activities, disrupts cell wall or membrane integrity and interferes with ergosterol biosynthesis. Thymol also functions as a redox-active compound inducing generation of reactive oxygen species and lipid peroxidation in fungal cells. Previously, we showed thymol significantly enhanced the in vitro growth inhibitory effect of difenoconazole against Bipolaris sorokiniana and Parastagonospora nodorum. More recently, we demonstrated a possibility to use thymol to overcome the resistance of a P. nodorum strain able to grow on difenoconazole-containing media. However, potential for thymol to serve as a chemosensitizing agent in seed or plant treatments, to provide an effective suppression of the above-mentioned plant pathogens by triazole fungicides applied in lowered dosages, had yet to be tested. In the work presented here, we showed combined treatments of naturally infected barley seeds with thymol and difenoconazole (Dividend® 030 FS) synergistically exacerbated the protective effect against common root rot agent, B. sorokiniana, and other fungi (Fusarium spp. and Alternaria spp.). Similarly, co-applied treatment of wheat seeds, artificially inoculated with Fusarium culmorum, resulted in equivalent reduction of disease incidence on barley seedlings as application of Dividend®, alone, at a ten-fold higher dosage. In foliar treatments of wheat seedlings, thymol combined with Folicur® 250 EC (a.i. tebuconazole) enhanced sensitivity of P. nodorum, a glume/leaf blotch pathogen, to the fungicide and provided a significant mitigation of disease severity on treated seedlings, compared to controls, without increasing Folicur® dosages. Folicur® co-applied with thymol was also significantly more effective against a strain of P. nodorum tolerant to Folicur® alone. No additional deoxynivalenol or zearalenone production was found when a toxigenic F. culmorum was cultured in a nutrient medium containing thymol at a concentration used for chemosensitization of root rot agents. Accordingly, F. culmorum exposure to thymol at the sensitizing concentration did not up-regulate key genes associated with the biosynthesis of trichothecene or polyketide mycotoxins in this pathogen. Further studies using field trials are necessary to determine if thymol-triazole co-applications result in sensitization of seed- and foliar-associated plant pathogenic fungi, and if thymol affects production of fusarial toxins under field conditions.

Chemosensitizing activity of peptide from Lentinus squarrosulus (Mont.) on cisplatin-induced apoptosis in human lung cancer cells

The limitations of cisplatin, a standard chemotherapy for lung cancer, have been documented with serious adverse effects and drug resistance. To address the need for novel therapy, this study firstly reveals the potential of peptide from Lentinus squarrosulus (Mont.) as a chemotherapeutic adjuvant for cisplatin treatment. The purified peptide from L. squarrosulus aqueous extracts was obtained after eluting with 0.4 M NaCl through FPLC equipped with anion exchange column. Preincubation for 24 h with 5 µg/mL of the peptide at prior to treatment with 5 µM cisplatin significantly diminished %cell viability in various human lung cancer cells but not in human dermal papilla and proximal renal cells. Flow cytometry indicated the augmentation of cisplatin-induced apoptosis in lung cancer cells pretreated with peptide from L. squarrosulus. Preculture with the peptide dramatically inhibited colony formation in lung cancer cells derived after cisplatin treatment. Strong suppression on integrin-mediated survival was evidenced with the diminution of integrins (β1, β3, β5, α5, αV) and down-stream signals (p-FAK/FAK, p-Src/Src, p-Akt/Akt) consequence with alteration of p53, Bax, Blc-2 and Mcl-1 in cisplatin-treated lung cancer cells preincubated with peptide from L. squarrosulus. These results support the development of L. squarrosulus peptide as a novel combined chemotherapy with cisplatin for lung cancer treatment.

Small-molecule screen reveals synergy of cell cycle checkpoint kinase inhibitors with DNA-damaging chemotherapies in medulloblastoma.

Medulloblastoma (MB) consists of four core molecular subgroups with distinct clinical features and prognoses. Treatment consists of surgery, followed by radiotherapy and cytotoxic chemotherapy. Despite this intensive approach, outcome remains dismal for patients with certain subtypes of MB, namely, MYC-amplified Group 3 and TP53-mutated SHH. Using high-throughput assays, six human MB cell lines were screened against a library of 3208 unique compounds. We identified 45 effective compounds from the screen and found that cell cycle checkpoint kinase (CHK1/2) inhibition synergistically enhanced the cytotoxic activity of clinically used chemotherapeutics cyclophosphamide, cisplatin, and gemcitabine. To identify the best-in-class inhibitor, multiple CHK1/2 inhibitors were assessed in mice bearing intracranial MB. When combined with DNA-damaging chemotherapeutics, CHK1/2 inhibition reduced tumor burden and increased survival of animals with high-risk MB, across multiple different models. In total, we tested 14 different models, representing distinct MB subgroups, and data were validated in three independent laboratories. Pharmacodynamics studies confirmed central nervous system penetration. In mice, combination treatment significantly increased DNA damage and apoptosis compared to chemotherapy alone, and studies with cultured cells showed that CHK inhibition disrupted chemotherapy-induced cell cycle arrest. Our findings indicated CHK1/2 inhibition, specifically with LY2606368 (prexasertib), has strong chemosensitizing activity in MB that warrants further clinical investigation. Moreover, these data demonstrated that we developed a robust and collaborative preclinical assessment platform that can be used to identify potentially effective new therapies for clinical evaluation for pediatric MB.

Improved Chemosensitization Activity of Carboxymethyl Chitosan/PVA Hydrogels by Plasma Surface Modification

As global population escalates; the need for better healthcare shall inevitably intensify. Current scenario, thus, calls for a versatile technology for the construction for smart biomaterials to cater to the needs. In this context; hydrogels comprising carboxymethyl chitosan and polyvinyl alcohol (CMCS/ PVA) were fabricated using a green crosslinker, tetraethyl orthosilicate. To enhance their bio-efficacy; cold plasma assisted surface tailoring of the aforesaid hydrogels was performed as a function of four different gases viz Air, Ar, He and N2. Apart from improving the surface wettability; plasma treatment endowed the hydrogels with an improved tensile strength. 5-Fluorouracil (5FU) release studies from the hydrogels validated their potential as oral colon-targeted delivery systems. Hemolytic experiments revealed no adverse effect on RBCs post-plasma treatment. Pristine hydrogels exhibited good cytocompatibility with MCF-7 cells. A strong cell growth inhibition was observed from 5FU-loaded hydrogels as validated by caspase-3 assay. Further assessment by the soil burial test revealed the hydrogels were biodegradable. Among all, the Ar-plasma treated hydrogel demonstrated superior hemocompatibility, chemosensitivity and biodegradability. Thus, cold plasma technology has invariably paved the path as an eco-friendly, economical and effectual strategy for development of novel CMCS/ PVA hydrogels in anticancer therapy.

Verminoside from Pseudolysimachion rotundum var. subintegrum sensitizes cisplatin-resistant cancer cells and suppresses metastatic growth of human breast cancer

Breast cancer is one of the most common cancers in women and is associated with a high mortality rate. The majority of deaths resulting from breast cancer are attributable to metastatic growth; in addition, chemoresistance is a major concern in the treatment of patients with breast cancer. However, limited drugs are available for the treatment of metastatic breast cancer. In this study, the chemoadjuvant effects of a methanolic extract from the leaves of Pseudolysimachion rotundum var. subintegrum (NC13) and an active component isolated from the plant, verminoside (Vms), were evaluated. Furthermore, their potent anti-metastatic activities were validated in vitro and in vivo in animal models. The anti-metastatic and chemosensitizing activities of NC13 and Vms on cisplatin treatment were found to be partly mediated by suppression of the epithelial–mesenchymal transition of cancer cells. Collectively, our results implied that NC13 and its bioactive component Vms could be developed as effective chemoadjuvants in combination with conventional therapeutics.

In vitro adjuvant antitumor activity of various classes of semi-synthetic poststerone derivatives

Various classes of semi-synthetic analogs of poststerone, the product of oxidative cleavage of the C20-C22 bond in the side chain of the phytoecdysteroid 20-hydroxyecdysone, were synthesized. The analogs were obtained by reductive transformations using L-Selectride and H2-Pd/C, by molecular abeo-rearrangements using the DAST reagent or ultrasonic treatment in the NaI-Zn-DMF system, and by acid-catalyzed reactions of poststerone derivatives with various aldehydes (o-FC6H4CHO, m-CF3C6H4CHO, CO2Me(CH2)8CHO). The products were tested on a mouse lymphoma cell line pair, L5178 and its ABCB1-transfected multi-drug resistant counterpart, L5178MDR, for their in vitro activity alone and in combination with doxorubicin, and for the ability to inhibit the ABCB1 transporter. Among the tested compounds, new 2,3-dioxolane derivatives of the pregnane ecdysteroid were found to have a pronounced chemosensitizing activity towards doxorubicin and could be considered as promising candidates for further structure optimization for the development of effective chemosensitizing agents.

Potent Synergistic Interactions between Lopinavir and Azole Antifungal Drugs against Emerging Multidrug-Resistant Candida auris.

The limited therapeutic options and the recent emergence of multidrug-resistant Candida species present a significant challenge to human medicine and underscore the need for novel therapeutic approaches. Drug repurposing appears as a promising tool to augment the activity of current azole antifungals, especially against multidrug-resistant Candida auris In this study, we evaluated the fluconazole chemosensitization activities of 1,547 FDA-approved drugs and clinical molecules against azole-resistant C. auris This led to the discovery that lopinavir, an HIV protease inhibitor, is a potent agent capable of sensitizing C. auris to the effect of azole antifungals. At a therapeutically achievable concentration, lopinavir exhibited potent synergistic interactions with azole drugs, particularly with itraconazole against C. auris (fractional inhibitory concentration index [ΣFICI] ranged from 0.04 to 0.09). Additionally, the lopinavir/itraconazole combination enhanced the survival rate of C. auris-infected Caenorhabditis elegans by 90% and reduced the fungal burden in infected nematodes by 88.5% (P < 0.05) relative to that of the untreated control. Furthermore, lopinavir enhanced the antifungal activity of itraconazole against other medically important Candida species, including C. albicans, C. tropicalis, C. krusei, and C. parapsilosis Comparative transcriptomic profiling and mechanistic studies revealed that lopinavir was able to significantly interfere with the glucose permeation and ATP synthesis. This compromised the efflux ability of C. auris and consequently enhanced the susceptibility to azole drugs, as demonstrated by Nile red efflux assays. Altogether, these findings present lopinavir as a novel, potent, and broad-spectrum azole-chemosensitizing agent that warrants further investigation against recalcitrant Candida infections.

Apigenin by targeting hnRNPA2 sensitizes triple-negative breast cancer spheroids to doxorubicin-induced apoptosis and regulates expression of ABCC4 and ABCG2 drug efflux transporters

Acquired resistance to doxorubicin is a major hurdle in triple-negative breast cancer (TNBC) therapy, emphasizing the need to identify improved strategies. Apigenin and other structurally related dietary flavones are emerging as potential chemo-sensitizers, but their effect on three-dimensional TNBC spheroid models has not been investigated. We previously showed that apigenin associates with heterogeneous ribonuclear protein A2/B1 (hnRNPA2), an RNA-binding protein involved in mRNA and co-transcriptional regulation. However, the role of hnRNPA2 in apigenin chemo-sensitizing activity has not been investigated. Here, we show that apigenin induced apoptosis in TNBC spheroids more effectively than apigenin-glycoside, owing to higher cellular uptake. Moreover, apigenin inhibited the growth of TNBC patient-derived organoids at an in vivo achievable concentration. Apigenin sensitized spheroids to doxorubicin-induced DNA damage, triggering caspase-9-mediated intrinsic apoptotic pathway and caspase-3 activity. Silencing of hnRNPA2 decreased apigenin-induced sensitization to doxorubicin in spheroids by diminishing apoptosis and partly abrogated apigenin-mediated reduction of ABCC4 and ABCG2 efflux transporters. Together these findings provide novel insights into the critical role of hnRNPA2 in mediating apigenin-induced sensitization of TNBC spheroids to doxorubicin by increasing the expression of efflux transporters and apoptosis, underscoring the relevance of using dietary compounds as a chemotherapeutic adjuvant.

Repurposing of quinoline alkaloids identifies their ability to enhance doxorubicin‐induced sub‐G0/G1 phase cell cycle arrest and apoptosis in cervical and hepatocellular carcinoma cells

The ability of quinoline alkaloids (cinchonine, cinchonidine, quinine, and quinidine) to sensitize different human cancer cell lines to doxorubicin (DOX)-induced cell death was evaluated. Cell viability was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the alkaloids ability to enhance DOX-induced apoptosis was explored using Western blotting analysis. Also, flow cytometry was applied to analyze cell fractions in the different cell cycle phases. All alkaloids showed a significant enhancement of DOX-induced cell death in HeLa and HepG2 cell lines. The chemosensitizing activity of the quinoline alkaloids was attributed to the induction of apoptosis as indicated by splitting of caspase-3 and its substrate poly (ADP-ribose) polymerase (PARP). In addition, there was an increase in the cell fractions in sub-G0/G1 phase in case of DOX combination with the alkaloids. This study proves the ability of the quinoline alkaloids to enhance DOX-induced apoptotic cell death in human cervical and hepatocellular carcinoma cells.

Abstract 571: Andrographolide enhances sensitivity to 5-fluorouracil by targeting ferroptosis-related genes in colorectal cancer

Abstract Purpose: Despite improvements in response rates from various treatment strategies, the 5-year survival rates for metastatic colorectal cancer (mCRC) remain dismal (~10-15%). One of the primary reasons for CRC therapy failure is development of acquired drug resistance to first line chemotherapies such as 5-fluorouracil (5FU), and nearly half of all mCRC patients are resistant to 5FU-based therapies. These limitations highlight the need for novel treatment strategies that offer improved efficacy and can help overcome acquired chemoresistance and enhance anti-cancer efficacy of conventional chemotherapies. Considering that some naturally-occurring botanicals have chemo-sensitizing properties, we analyzed the potential of andrographolide, a botanical with key biological activities, including anti-inflammatory, antitumorigenic, apoptotic, antiangiogenic and immunomodulatory activities, in reversing chemoresistance in CRC, and also delineated the associated molecular pathways underpinning this activity. Experimental design: We performed a series of in-vitro and in-vivo experiments to investigate the chemo-sensitizing ability of andrographolide in 5-FU resistant (5FUR) CRC cells, xenografts animal models and CRC-derived organoids. Furthermore, we performed gene expression microarrays and other mechanistic studies to explore the molecular mechanisms responsible for its chemo-sensitizing activity. Results: Andrographolide treatment significantly enhanced the efficacy of 5FU in HCT116 5FUR and SW480 5FUR cells, as evidenced by enhanced apoptosis and decreased proliferation rates (p&amp;lt;0.05). In line with our in-vitro findings, treatment with andrographolide also led to significant tumor growth inhibition in a xenograft animal model (p&amp;lt;0.0001). Likewise, in accordance with the results from cell lines and mice xenografts, the combination of 5FU and andrographolide significantly decreased the growth of patient-derived tumor organoids compared to those treated with 5FU alone (p&amp;lt;0.01 for patient 1, p&amp;lt;0.05 for patient 2). Through microarray-based gene expression profiling analysis in 5FU-resistant CRC cells, we identified ferroptosis and WNT signaling as the key cancer associated pathways responsible for andrographolide mediated chemo-sensitization in CRC cells. Taken together, using genome-wide gene expression analysis, we delineated the mechanism underlying the chemo-sensitizing properties of andrographolide and made a case for the potential use of andrographolide for enhancing the therapeutic efficacy of 5FU in CRC. Conclusion: Our data provides first evidence for andrographolide mediated sensitization to 5FU based therapy, through modulation of ferroptosis pathway in CRC. These results highlight the potential adjunctive therapeutic role for andrographolide in combination with conventional chemotherapeutic drug in patients with CRC. Citation Format: Priyanka Sharma, Tadanobu Shimura, Jasjit K Banwait, Ajay Goel. Andrographolide enhances sensitivity to 5-fluorouracil by targeting ferroptosis-related genes in colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 571.