Drug Resistance In Human Cancer Cells Research Articles

Development of Natural-Product-Inspired ABCB1 Inhibitors Through Regioselective Tryptophan C3-Benzylation.

The emergence of drug resistance in canceris a serious threat. Upregulation ofABC/P-gptransporters significantly contributes to thisemergence.Despite30 years of efforts,the search for effective ABC/P-gp inhibitors withminimaltoxicity to human cells, isstill underway.Inspired by Nocardioazine A, a marine alkaloid that inhibitsP-gp, we report a regioselective pathway to createindole-C3-benzyl cyclo-L-Trp-L-Trp DKPs. We have reported thatexo-C3-N-Dbn--Trp2 (13) as a lead ABCB1 inhibitor that is more effective than Verapamil. C3N-Dbn-Trp2 restored chemotherapy sensitivity in drug-resistant human cancer cells and had no adverse effect on cell proliferation.Herein, we report several suchC3-functionalized pyrroloindolines as ABCB1 inhibitors.Results arising from the molecular docking studies indicate that the interactions at the access tunnel between ABCB1 and the inhibitor result in a powerful predictor for the efficacy of the inhibitor. Based on fluorescence-based assays, we conclude that the most efficacious inhibitor is the p-cyano-derived exo-C3-N-Dbn--Trp2 (33a), closely followed by several analogues. We correlate that the predictions based on the inhibitor interactions at the access tunnel provide clues about the design of improved ABCB1 inhibitors. This work lays the foundation for the design of a new class of inhibitors from acyclo-L-Trp-L-Trp DKP scaffold.

Exploring bat-inspired cyclic tryptophan diketopiperazines as ABCB1 Inhibitors

Chemotherapy-induced drug resistance remains a major cause of cancer recurrence and patient mortality. ATP binding cassette subfamily B member 1 (ABCB1) transporter overexpression in tumors contributes to resistance, yet current ABCB1 inhibitors have been unsuccessful in clinical trials. To address this challenge, we propose a new strategy using tryptophan as a lead molecule for developing ABCB1 inhibitors. Our idea stems from our studies on bat cells, as bats have low cancer incidences and high ABCB1 expression. We hypothesized that potential ABCB1 substrates in bats could act as competitive inhibitors in humans. By molecular simulations of ABCB1-substrate interactions, we generated a benzylated Cyclo-tryptophan (C3N-Dbn-Trp2) that inhibits ABCB1 activity with efficacy comparable to or better than the classical inhibitor, verapamil. C3N-Dbn-Trp2 restored chemotherapy sensitivity in drug-resistant human cancer cells with no adverse effect on cell proliferation. Our unique approach presents a promising lead toward developing effective ABCB1 inhibitors to treat drug-resistant cancers.

Synthesis and new DNA targeting activity of 6- and 7-tert-butylfascaplysins

Fascaplysin is a red cytotoxic pigment with anticancer properties isolated from the marine sponge Fascaplysinopsis sp. Recently, structure–activity relationship analysis reported by our group suggested that selective cytotoxicity of fascaplysin derivatives towards tumor cells negatively correlates with their ability to intercalate into DNA. To validate this hypothesis, we synthesized 6- and 7-tert-butylfascaplysins which reveal mitigated DNA-intercalating properties. These derivatives were found to be strongly cytotoxic to drug-resistant human prostate cancer cells, albeit did not demonstrate improved selectivity towards cancer cells when compared to fascaplysin. At the same time, kinome analysis suggested an activation of CHK1/ATR axis in cancer cells shortly after the drug exposure. Further experiments revealed induction of replication stress that is eventually converted to the toxic DNA double-strand breaks, resulting in caspase-independent apoptosis-like cell death. Our observations highlight new DNA-targeting effect of some fascaplysin derivatives and indicate more complex structure–activity relationships within the fascaplysin family, suggesting that cytotoxicity and selectivity of these alkaloids are influenced by multiple factors. Furthermore, combination with clinically-approved inhibitors of ATR/CHK1 as well as testing in tumors particularly sensitive to the DNA damage should be considered in further studies.

Self-Assembly of Erlotinib-Platinum(II) Complexes for Epidermal Growth Factor Receptor-Targeted Photodynamic Therapy.

Due to cell mutation and self-adaptation, the application of clinical drugs with early epidermal growth factor receptor (EGFR)-targeted inhibitors is severely limited. To overcome this limitation, herein, the synthesis and in-depth biological evaluation of an erlotinib-platinum(II) complex as an EGFR-targeted anticancer agent is reported. The metal complex is able to self-assemble inside an aqueous solution and readily form nanostructures with strong photophysical properties. While being poorly toxic toward healthy cells and upon treatment in the dark, the compound was able to induce a cytotoxic effect in the very low micromolar range upon irradiation against EGFR overexpressing (drug resistant) human lung cancer cells as well as multicellular tumor spheroids. Mechanistic insights revealed that the compound was able to selectively degrade the EGFR using the lysosomal degradation pathway upon generation of singlet oxygen at the EGFR. We are confident that this work will open new avenues for the treatment of EGFR-overexpressing tumors.

Tripterygium glycosides reverse chemotherapy resistance in ovarian cancer by targeting the NRF2/GPX4 signal axis to induce ferroptosis of drug-resistant human epithelial ovarian cancer cells

Cisplatin resistance is the main cause of postoperative recurrence and difficulty in the treatment of ovarian cancer. It is urgently needed to identify therapeutic drugs with unique functions to overcome the current challenges in the treatment of ovarian cancer. In this study, we found that TG promoted the accumulation of ROS and MDA in A2780/DDP cells and downregulated the expression of key antioxidant molecules. In vivo, the survival rate of tumor-bearing nude mice was prolonged by TG without significant hepatotoxic reaction. The expression of key antioxidant molecules in tumor tissues was consistent with that in vitro. These findings revealed that TG disrupted homeostasis of redox reactions and induced ferroptosis in A2780/DDP cells, thereby enhancing cisplatin chemosensitivity of ovarian cancer. Overall, TG may be a novel potential therapeutic option for reversing resistance to cisplatin chemotherapy.

Cytotoxicity of the methanol extracts and compounds of Brucea antidysenterica (Simaroubaceae) towards multifactorial drug-resistant human cancer cell lines

BackgroundCancer remains a global health concern and constitutes an important barrier to increasing life expectancy. Malignant cells rapidly develop drug resistance leading to many clinical therapeutic failures. The importance of medicinal plants as an alternative to classical drug discovery to fight cancer is well known. Brucea antidysenterica is an African medicinal plant traditionally used to treat cancer, dysentery, malaria, diarrhea, stomach aches, helminthic infections, fever, and asthma. The present work was designed to identify the cytotoxic constituents of Brucea antidysenterica on a broad range of cancer cell lines and to demonstrate the mode of induction of apoptosis of the most active samples.MethodsSeven phytochemicals were isolated from the leaves (BAL) and stem (BAS) extract of Brucea antidysenterica by column chromatography and structurally elucidated using spectroscopic techniques. The antiproliferative effects of the crude extracts and compounds against 9 human cancer cell lines were evaluated by the resazurin reduction assay (RRA). The activity in cell lines was assessed by the Caspase-Glo assay. The cell cycle distribution, apoptosis via propidium iodide (PI) staining, mitochondrial membrane potential (MMP) through 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining, and the reactive oxygen species (ROS) via 2´,7´-dichlorodihydrofluoresceine diacetate (H2DCFH-DA) staining, were investigated by flow cytometry.ResultsPhytochemical studies of the botanicals (BAL and BAS) led to the isolation of seven compounds. BAL and its constituents 3, (3-(3-Methyl-1-oxo-2-butenyl))1H indole (1) and hydnocarpin (2), as well as the reference compound, doxorubicin, had antiproliferative activity against 9 cancer cell lines. The IC50 values varied from 17.42 µg/mL (against CCRF-CEM leukemia cells) to 38.70 µg/mL (against HCT116 p53−/− colon adenocarcinoma cells) for BAL, from 19.11 µM (against CCRF-CEM cells) to 47.50 µM (against MDA-MB-231-BCRP adenocarcinoma cells) for compound 1, and from 4.07 µM (against MDA-MB-231-pcDNA cells) to 11.44 µM (against HCT116 p53+/+ cells) for compound 2. Interestingly, hypersensitivity of resistant cancer cells to compound 2 was also observed. BAL and hydnocarpin induced apoptosis in CCRF-CEM cells mediated by caspase activation, the alteration of MMP, and increased ROS levels.ConclusionBAL and its constituents, mostly compound 2, are potential antiproliferative products from Brucea antidysenterica. Other studies will be necessary in the perspective of the discovery of new antiproliferative agents to fight against resistance to anticancer drugs.

Retracted: Effects of Anesthetics on Proliferation and Apoptosis of Drug-Resistant Human Colon Cancer Cells.

[This retracts the article DOI: 10.1155/2022/4080585.].

Downregulation of MACC1 facilitates the reversal effect of verapamil on the chemoresistance to active metabolite of irinotecan in human colon cancer cells

The aim of this study is to investigate the reversal effect of verapamil (VER) on chemoresistance to irinotecan (CPT-11) in human colon cancer cells and relevant mechanisms. Cell counting kit-8 (CCK-8) test and colony-forming unit (CFU) experiment results show that VER strengthens the sensitivity of human colon cancer cell line HT29 to CPT-11 but has a small effect on SW480 cells. High-throughput transcriptome sequencing, RT-PCR, and Western blot results show that the inhibition of metastasis-associated in colon cancer-1 (MACC1) expression by VER is the key factor for reversal effect on chemoresistance to CPT-11. Transfection experiments further show that VER can reverse the resistance of human colon cancer cells to SN-38, the active metabolite of CPT-11, when MACC1 is overexpressed. The nude mouse transplantation tumor experiment provides an in vivo proof that VER can strengthen sensitivity to CPT-11 in drug-resistant human colon cancer cells, and the effect might be related to the inhibited expression of MACC1. In summary, VER might strengthen the reversal effect of VER on chemoresistance to CPT-11 in human colon cancer cells and facilitate the apoptosis of human colon cancer cells by downregulating MACC1 expression.

Effects of Anesthetics on Proliferation and Apoptosis of Drug-Resistant Human Colon Cancer Cells.

In recent years, people's living standards are getting higher and higher, and life pressure is also increasing, and there are also many problems in eating habits. This is also the direct cause of colon cancer. The aim of this paper was to investigate whether anesthetic drugs could positively affect the proliferation and apoptosis of colon cancer cells. In this paper, the significance of anesthetic drugs is proposed, and an artificial neural network algorithm based on artificial intelligence is proposed. It is well known that artificial neural networks play an important role in medicine. The experimental results of this paper show that the incidence of colon cancer in 2020 will be in the range of 5%-35%, and the incidence of colon cancer in 2021 will be in the range of 7%-30%. While colon cancer rates in 2021 do not appear to be as high as colon cancer rates in 2020, they are generally much higher than colon cancer rates in 2020. It can be seen that as the population ages, the number of colon cancer patients is increasing due to the lack of emphasis on health. This also means that the incidence of colon cancer is getting higher and higher, and traditional drug chemotherapy has been unable to play a good role in inhibiting the proliferation of colon cancer cells. Therefore, this paper investigated the effects of anesthetic drugs on the proliferation and apoptosis of human colon cancer cells.

Isoxanthohumol exerts anticancer activity against drug-resistant thyroid cancer cells by inhibiting cell migration and invasion, apoptosis induction and targeting PI3K/AKT/m-TOR signaling pathway


 
 
 
 Purpose: To investigate the anticancer effect of isoxanthohumol against drug-resistant thyroid cancer cells. Its effect on cellular PI3K/AKT/m-TOR signaling pathway, cell migration and invasion and apoptosis were also analyzed.
 Methods: The cytotoxicity of isoxanthohumol drug was examined by MTT assay. Cellular morphology was assessed by phase contrast microscopy. Fluorescence microscopy and western blotting were used to evaluate its effect on cellular apoptosis. Further, western blotting was used to monitor the levels of expression of proteins linked to PI3K/AKT/m-TOR signaling pathway.
 Results: Isoxanthohumol significantly (p<0.05) inhibited the proliferation and progression of drug-resistant human papillary BCPAP cancer cells in a concentration- and time-dependent manner. Further, morphological assessment of BCPAP cells indicate that there were proapoptotic alterations after isoxanthohumol treatment. The results for apoptosis in BCPAP cells showed enhanced number of apoptotic cells, elevated levels of proapoptotic proteins (including Bax), and increased level of expressions of caspase-3 and caspase-9. Isoxanthohumol targeted metastatic features of BCPAP cells by inhibiting both cell migration and cell invasion in a concentration-dependent manner. Western blotting revealed remarkable inhibition of PI3K/AKT/m-TOR signalling pathway through blocking of expression of its allied proteins.
 Conclusion: Isoxanthohumol exhibits potent anticancer effect in human papillary cancer cells by inducing apoptosis, inhibition of cell migration, as well as invasion and targeting PI3K/AKT/m-TOR signalling pathway. These findings could play a significant role in drug design and discovery for thyroid cancer. However, more conformational investigations are required.
 
 
 

Betulinic acid targets drug-resistant human gastric cancer cells by inducing autophagic cell death, suppresses cell migration and invasion, and modulates the ERK/MEK signaling pathway.

The main purpose of this study was to examine the anticancer effects of betulinic acid - a plant triterpene, against gastric cancer, along with demonstrating its underlying mechanism. The MTT assay and clonogenic assays were executed to assess cellular viability in control and betulinic acid treated cells. Transmission electron microscopy and western blotting were implemented to study autophagy stimulation by betulinic acid. The ERK/MEK signaling pathway was monitored by western blotting. Migration and invasion of SGC-7901 cells was investigated via transwell chamber assay. Results of this investigation indicated that betulinic acid induced remarkable cytotoxicity against gastric cancer SGC-7901 cells, in contrast to normal gastric GES-1 cells. The cytotoxicity of betulinic acid was observed due to its autophagy stimulation tendency in target cells. Autophagic cell death was supported by the data attained from western blotting showing enhanced LC3-II, and lowered LC3-I and p62 expressions. Moreover, betulinic acid was observed to block the ERK/MEK signaling pathway in SGC-7901 cells, which was associated with declined levels of expressions of the phosphorylated ERK and MEK proteins. Finally, the transwell chamber assay revealed a potential lowering of migration and invasion by betulinic acid in the SGC-7901 cells. In conclusion, these results demonstrated that betulinic acid exhibited significant anti-gastric cancer effects mediated via autophagy induction, blocking of ERK/MEK signaling and suppression of migration and invasion. Therefore, betulinic acid may prove as a lead molecule in gastric cancer management and research.

Abstract 281: pH-sensitive liposome for siRNA delivery to treat drug-resistant ovarian cancer

Abstract Introduction: With a 5-year survival rate of 47%, ovarian cancer is the 5th leading cause of death amongst women worldwide. Over 75% of patients experience recurrence after initial treatment, indicating a need for improved treatment options. Drug resistance is a major barrier hindering the success of current treatment methods. Our study analyzes the characteristics of a stimuli-sensitive liposomal delivery system for combatting drug resistance. Our delivery system will deliver bioactive siRNAs targeting genes related to drug resistance, cell proliferation, and apoptosis. In this study, we investigate the characteristics of the liposomes to determine particle size, surface charge, and ability to encapsulate/bind both siRNAs. We also begin to investigate the delivery potential of the pH-sensitive liposomal formulation in vitro using ovarian cancer cell lines. Methods: Empty and siRNA loaded cationic, pH-sensitive liposomes (CHEMS-LPs) were synthesized by the thin-film hydration method. Liposome size, zeta potential, and polydispersity index (PDI) were measured by dynamic light scattering (DLS). To measure siRNA encapsulation efficiency, fluorescently labeled siRNA was loaded into CHEMS-LPs and subjected to centrifugation to pellet the LPs. Fluorescence spectroscopy was used to detect siRNA in the supernatant. The toxicity of unloaded CHEMS-LPs was determined by an MTS assay using OVCAR3 (drug-sensitive) and OVCAR3-T40 (drug-resistant) human ovarian cancer cells. Results: The size and zeta potential of blank and siRNA-loaded CHEMS-LPs were 97.88 ± 2.39 nm and 29.0 ± 2.00 mV, and 80.78 ± 0.77​ nm and 13.1 ±1.66​ mV, respectively. The positively charged zeta potential confirms the cationic nature of our liposomes. The PDI demonstrated that the liposomes were unimodal and monodisperse with PDI values of less than 0.300 for each formulation. In addition, siRNA was successfully bound to CHEMS-LPs through electrostatic interaction with the cationic lipid layer, resulting in an encapsulation efficiency of 99.6% Conclusion: CHEMS-LPs are pH-sensitive, cationic, monodisperse liposomes able to encapsulate siRNAs in order to mediate delivery into ovarian cancer cells. Their stable structure, positive charge, and low cytotoxicity is promising for future studies, including delivery of bioactive siRNAs to stimulate downregulation of target genes related to drug resistance. Acknowledgements: This work was supported in part by the National Science Foundation EPSCoR Program under Award # OIA-1655740. We would like to thank George Duran from Stanford University for donating the OVCAR3-T40 cell line. Citation Format: Kharimat Lora Alatise, Samantha Gardner, Angela Alexander-Bryant. pH-sensitive liposome for siRNA delivery to treat drug-resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 281.

3D Clinorotation Affects Drug Sensitivity of Human Ovarian Cancer Cells

Numerous studies have reported that gravity alteration displays a remarkable influence on the biological processes of cancer cells. Therefore, gravity-related experiments have become a promising method of improving knowledge in the field of cancer biology and may be useful to detect remarkable implications for future cancer treatment. Taking this concept further, we used a 3D clinostat (3D-C; 10 rpm of changing direction) to analyse the effect of short-term exposure to simulated microgravity (sμg) on cisplatin sensitivity of drug resistant human ovarian cancer cells SKOV-3. This allowed us to investigate whether altered gravity affects drug susceptibility of cancer cells. Our studies revealed that sμg exposure affects SKOV-3 cells morphology and drug efficiency. We observed the altered cell shape, the presence of membrane blebbing and lamellipodia as well as the lack of filopodia when the cells had been cultured on 3D-C for 2 h. Cytotoxicity, cell death and cell cycle assays showed an increased percentage of apoptotic cells and G0/G1 cell cycle arrest after exposure on the 3D-C with cisplatin in comparison to the static control, non clinorotated cells. Cell proliferation and migration were altered after the exposure to sμg as well. Our studies suggest that the altered gravity conditions affected cellular mechanisms involved in cisplatin resistance, resulting in higher sensitivity of cancer cells to the chemotherapeutic. The investigation and clarification of these results may be a crucial step toward improving our understanding of the relationship between cellular resistance to chemotherapy and the response to altered gravitational conditions.

Retracted: Phillygenin Exerts In Vitro and In Vivo Antitumor Effects in Drug-Resistant Human Esophageal Cancer Cells by Inducing Mitochondrial-Mediated Apoptosis, ROS Generation, and Inhibition of the Nuclear Factor kappa B NF-κB Signalling Pathway.

An editorial decision has been made to retract this manuscript due to breach of publishing guidelines, following the identification of non-original and manipulated figures. Reference: Jiantao He, Wei Wei, Qingbo Yang, Yiling Wang: Phillygenin Exerts In Vitro and In Vivo Antitumor Effects in Drug-Resistant Human Esophageal Cancer Cells by Inducing Mitochondrial-Mediated Apoptosis, ROS Generation, and Inhibition of the Nuclear Factor kappa B NF-kappaB Signalling Pathway. Med Sci Monit 2019; 25:739-745.10.12659/MSM.913138.

4-Vinylguaiacol, an Active Metabolite of Ferulic Acid by Enteric Microbiota and Probiotics, Possesses Significant Activities against Drug-Resistant Human Colorectal Cancer Cells.

Ferulic acid, a hydroxycinnamic acid, is abundant in vegetables, grains, and medicinal plants. Emerging evidence suggests that ferulic acid may exert beneficial effects against colorectal cancer. However, the anticancer activity of ferulic acid is relatively low, and its metabolism after oral administration is largely unknown. In this study, mimicking the enteric environment, human intestinal microflora and commercial probiotics were used to metabolize ferulic acid to its metabolites, and their anticancer activities were evaluated. Ferulic acid can be biotransformed to 4-vinylguaiacol (2-methoxy-4-vinylphenol), and the contents of ferulic acid and 4-vinylguaiacol in bio-transformed extracts were determined by high-performance liquid chromatography (HPLC). Using the chemotherapy-sensitive cell line HCT-116 and the chemo-resistant cell line HT-29, the cell proliferation was determined by the modified trichrome stain assay. The cell cycle and induction of apoptosis were assayed using flow cytometry. HPLC data showed that there was a marked transformation from ferulic acid to 4-vinylguaiacol, and the conversion rates of intestinal microflora and four probiotics were from 1.3 to 36.8%. Both ferulic acid and 4-vinylguaiacol possessed dose- and time-related anticancer activities on the two cell lines, while 4-vinylguaiacol showed more potent effects than ferulic acid. Interestingly, 4-vinylguaiacol exhibited significantly higher antiproliferative effects on the HT-29 cell line than that on HCT-116. The IC50 of the metabolite 4-vinylguaiacol on HT-29 cells was 350 μM, 3.7-fold higher than its parent compound. The potential of cancer cell growth inhibition of 4-vinylguaiacol was mediated by cell cycle arrest at the G1 phase and induction of apoptosis. Data from this study indicate that the oral administration of ferulic acid offers a promising approach to increase its anticancer activity through gut microbial conversion to 4-vinylguaiacol, and the biotransformation could also be achieved by selected commercial probiotics. 4-Vinylguaiacol is a potential anticancer metabolite from ferulic acid for chemotherapy-resistant colon cancer cells.

Effects of kefir on doxorubicin-induced multidrug resistance in human colorectal cancer cells

Kefir, an acidic-alcoholic fermented milk product, is known to be associated with reduced cancer incidence. Multidrug resistance (MDR) against chemotherapeutic agents frequently occurs in cancer cells, leading to cancer therapy failure. To explore the potential chemo-sensitizing effects of kefir (i.e., kefir supernatant), drug-resistant human colorectal cancer cells (HT-29) were produced by exposing cells to 34 nm of doxorubicin (DOX) for 12 weeks. Results demonstrated that cells treated with kefir attenuated MDR and improved the anticancer effect of DOX in drug-resistant cells. Kefir increased intracellular accumulation of ROS and DOX in drug-resistant cells. Kefir decreased the gene and protein expressions of adenosine tri-phosphate binding cassette (ABC) transporters, a drug efflux pump, in drug-resistant cells. Upstream regulators of ABC transporters, such as ERK 1/2, JNK and NF-κB were also modulated by kefir. Our data suggest that kefir consumption may be helpful in patients receiving DOX chemotherapy owing to its chemo-sensitizing effects.

Bioactive Hexapeptide Reduced the Resistance of Ovarian Cancer Cells to DDP by Affecting HSF1/HSP70 Signaling Pathway.

Ovarian cancer is the leading cause of death in gynecologic malignancies. Ovarian cancer as a metastatic malignant tumor is highly recurrent and prone to drug resistance. Bioactive peptides are an emerging area of biomedical research in reducing resistance of tumor cell to drugs. In this paper, we investigated the effects and mechanisms of bioactive hexapeptide (PGPIPN) derived in milk protein on the sensitivity of ovarian cancer cells to cis-dichlorodiammine platinum (DDP). Human ovarian cancer cell lines (SKOV3 and COC1), their DDP-resistant sublines (SKOV3/DDP and COC1/DDP) and human primary ovarian cancer cells were cultured in vitro under the combined treatment of DDP (close to IC50) and different concentrations of PGPIPN. The viabilities, apoptosis and cell cycle changes were respectively measured by WST-8 and flow cytometry. The mRNA and protein expression levels of HSF1, HSP70, MDR1, ERCC1 and β-actin gene were respectively assayed by RT-qPCR and western blotting. The results showed that PGPIPN significantly increased the sensitivity of human ovarian cancer cells to DDP in inhibiting viability and inducing apoptosis in vitro. But the effects in sensitive cells were lower than DDP-resistant cells. PGPIPN significantly changed the cell cycles in all human ovarian cancer cells, which leaded to a significant increase in the percentage of cells blocked at G2/M phase and decrease the percentage of cells at G1 phases in a dose-dependent manner. PGPIPN affected the expression levels of HSF1, HSP70, MDR1 and ERCC1 genes. Compared with cells in DDP treatment alone, the expression levels of HSF1 and HSP70 in human ovarian cancer cells treated with DDP and PGPIPN together significantly decreased in dose-dependent manner. PGPIPN significantly decreased MDR1 and ERCC1 of drug-resistant ovarian cancer cell lines and human primary ovarian cancer cell in a dose-dependent manner. Pifithrin-μ (PFTμ, HSP70 inhibitor) decreased or removed the effects of peptide in increasing the sensitivity of ovarian cancer cells to DDP. This suggests that PGPIPN enhanced the sensitivity of ovarian cancer cells to DDP partially via reducing the activity of HSF1/HSP70 signaling pathway, thus inducing cell apoptosis and decreasing repairment of DNA damage.

Maackia amurensis agglutinin induces apoptosis in cultured drug resistant human non-small cell lung cancer cells.

The emergence of multi drug resistance in non-small cell lung cancer (NSCLC) patients is a major challenge towards the efficacy of chemotherapy. Thus, there is an urgent need for the newer, better clinically targeted strategies to treat this disease. Earlier studies from our laboratory revealed the apoptotic activity of Maackia amurensis agglutinin (MAA) in human NSCLC cells. In this study, the effect of MAA on drug resistant NSCLC cells was investigated. Two Paclitaxel-resistant NSCLC sub-lines (A549/PTX100 and NCI-H460/PTX100) were developed from A549 & NCI-H460 cell lines respectively. The generation of drug resistance phenotype was confirmed by the expression of cell surface MDR-1. Both the drug resistant sub-lines showed distinct morphological alterations. MAA interacted with the cell-surface protein(s) of apparent Mr ~66kDa and induced apoptosis in both the sub-lines through intrinsic/mitochondrial pathway, involving reduction in mitochondrial trans-membrane potential, up-regulation of Bax, unaltered/decreased expression of Bcl-XL, release of mitochondrial cytochrome c into the cytosol and activation of pro-caspases (-9&-3). Our findings highlighted the potential of this plant agglutinin to serve as an apoptosis inducing agent in drug resistant NSCLC cells.

Optical detection of the structural properties of tumor tissue generated by xenografting of drug-sensitive and drug-resistant cancer cells using partial wave spectroscopy (PWS).

A mesoscopic physics-based optical imaging technique, partial wave spectroscopy (PWS), has been used for the detection of cancer by probing nanoscale structural alterations in cells/tissue. The development of drug-resistant cancer cells/tissues during chemotherapy is a major challenge in cancer treatment. In this paper, using a mouse model and PWS, the structural properties of tumor tissue grown in 3D structures by xenografting drug-resistant and drug-sensitive human prostate cancer cells having 2D structures, are studied. The results show that the 3D xenografted tissues maintain a similar hierarchy of the degree of structural disorder properties as that of the 2D original drug-sensitive and drug-resistant cells.

Prooxidative Activity of Celastrol Induces Apoptosis, DNA Damage, and Cell Cycle Arrest in Drug-Resistant Human Colon Cancer Cells.

Cancer resistance to chemotherapy is closely related to tumor heterogeneity, i.e., the existence of distinct subpopulations of cancer cells in a tumor mass. An important role is assigned to cancer stem cells (CSCs), a small subset of cancer cells with high tumorigenic potential and capacity of self-renewal and differentiation. These properties of CSCs are sustained by the ability of those cells to maintain a low intracellular reactive oxygen species (ROS) levels, via upregulation of ROS scavenging systems. However, the accumulation of ROS over a critical threshold disturbs CSCs—redox homeostasis causing severe cytotoxic consequences. In the present study, we investigated the capacity of celastrol, a natural pentacyclic triterpenoid, to induce the formation of ROS and, consequently, cell death of the colon cancer cells with acquired resistant to cytotoxic drugs (LOVO/DX cell line). LOVO/DX cells express several important stem-like cell features, including a higher frequency of side population (SP) cells, higher expression of multidrug resistant proteins, overexpression of CSC-specific cell surface marker (CD44), increased expression of DNA repair gene (PARP1), and low intracellular ROS level. We found that celastrol, at higher concentrations (above 1 μM), significantly increased ROS amount in LOVO/DX cells at both cytoplasmic and mitochondrial levels. This prooxidant activity was associated with the induction of DNA double-strand breaks (DSBs) and apoptotic/necrotic cell death, as well as with inhibition of cell proliferation by S phase cell cycle arrest. Coincubation with NAC, a ROS scavenger, completely reversed the above effects. In summary, our results provide evidence that celastrol exhibits effective cytotoxic effects via ROS-dependent mechanisms on drug-resistant colon cancer cells. These findings strongly suggest the potential of celastrol to effectively kill cancer stem-like cells, and thus, it is a promising agent to treat severe, resistant to conventional therapy, colon cancers.