Mechanisms Of Cell Resistance Research Articles

Repeated ionizing radiation exposure induces TRIP13 expression, conferring radioresistance in lung cancer cells

Repeated ionizing radiation exposure induces TRIP13 expression, conferring radioresistance in lung cancer cells

Elucidating the Mechanisms of Acquired Palbociclib Resistance via Comprehensive Metabolomics Profiling.

Palbociclib is a cyclin-dependent kinase 4/6 inhibitor and a commonly used antitumor drug. Many cancers are susceptible to palbociclib resistance, however, the underlying metabolism mechanism and extent of resistance to palbociclib are unknown. In this study, LC-MS metabolomics was used to investigate the metabolite changes of colorectal cancer SW620 cells that were resistant to palbociclib. The study indicated that there were 76 metabolite expression differences between SW620 cells with palbociclib resistance and the parental SW620 cells involving amino acids, glutathione, ABC transporters, and so on. MetaboAnalyst 6.0 metabolic pathway analysis showed that arginine synthesis, β-alanine metabolism, and purine metabolism were disrupted. These results may provide potential clues to the metabolism mechanism of drug resistance in cancer cells that are resistant to palbociclib. Our study has the potential to contribute to the study of anti-palbociclib resistance.

Impact of cataranthine treatment on miRNA34 and miRNA29 levels in HepG2 cells and their association with the expression levels of Bcl-2 and Nrf2.

Cataranthine is an alkaloid used in the development of anti-cancer drugs. In this study, the effect of cataranthine is assessed by measuring the levels of miR-34 and miRNA-29, which are effective regulators of BCL-2 and NRF-2 gene expression, and their relation to the survival of HCC cells. This study used cataranthine, and the HepG2 cell line. The MTT test was used to determine the appropriate concentration of cataranthine for treatment (IC50). Oxidative stress status was assessed by evaluating TAC (total antioxidant capacity), TOS (total oxidant status), and MAD (malondialdehyde) levels. Flow cytometry was used to investigate apoptosis. The expression levels of Nrf2, Bcl2, miRNA34, and miRNA29 genes in HepG2 were evaluated by RT-PCR. We observed that cataranthine significantly reduced the levels of oxidative markers (MAD, and TOS) and, conversely, increased the level of antioxidant markers in HepG2 cells. Treatment of HepG2 cells with different doses of cataranthine significantly increased the expression of Nrf2 and Bcl-2 genes, while significantly decreasing the expression of miR29 and miR34 genes. These findings suggest that cataranthine may exert its anticancer effects by reducing oxidative stress and promoting apoptosis, while decrease in miR34 and miR29 as well as increase in Nrf2 and Bcl2 may act as resistance mechanisms in cancer cells. The results highlight the dual potential of cataranthine in regulating cellular responses to oxidative stress and cell death in liver cancer, with dose-dependent modulatory effects.

LncRNAs in modulating cancer cell resistance to paclitaxel (PTX) therapy.

Paclitaxel (PTX) is widely used for treating several cancers, including breast, ovarian, lung, esophageal, gastric, pancreatic, and neck cancers. Despite its clinical utility, cancer recurrence frequently occurs in patients due to the development of resistance to PTX. Resistance mechanisms in cancer cells treated with PTX include alterations in β-tubulin, the target molecule involved in mitosis, activation of molecular pathways enabling drug efflux, and dysregulation of apoptosis-related proteins. Long non-coding RNAs (lncRNAs), which are RNA molecules longer than 200 nucleotides without protein-coding potential, serve diverse regulatory roles in cellular processes. Increasing evidence highlights the involvement of lncRNAs in cancer progression and their contribution to PTX resistance across various cancers. Consequently, lncRNAs have emerged as potential therapeutic targets for addressing drug resistance in cancer treatment. This review focuses on the current understanding of lncRNAs and their role in drug resistance mechanisms, aiming to encourage further investigation in this area. Key lncRNAs and their associated pathways linked to PTX resistance will be summarized.

Effects of Curcumin and Its Analogue Desmethoxycurcumin on miR-133b and Its Target Gene GSTP-1 in Cisplatin-resistant Ovarian Cancer Cells.

Ovarian cancer, despite being the fifth most common gynecological malignancy, has the highest mortality rate. Recent clinical studies have explored the potential of natural products, like curcumin (CUR), to enhance conventional chemotherapy by targeting multiple cellular pathways. This study aimed to evaluate the effects of CUR and its analog, demethoxycurcumin (DMC), on human ovarian cancer and cisplatin-resistant ovarian cancer cell proliferation and apoptosis. Additionally, we investigated the expression of a candidate gene (GSTP-1), and microRNA (miR-133b) involvement in glutathione metabolism, a potential resistance mechanism in cisplatin-resistant ovarian cancer cells. Cell proliferation was measured using the WST-1 assay after exposing cisplatin-resistant (A2780cp) and sensitive (A2780) ovarian cancer cell lines to various concentrations of CUR and DMC for different time periods. Apoptosis was quantified using the Annexin V-FITC/PI assay. To understand the underlying mechanisms, we examined the expression levels of GSTP-1 and miR-133b using quantitative RT-PCR. The WST-1 assay revealed that CUR and DMC inhibited cell proliferation in both cell lines, with cisplatin causing a sharper viability decline in A2780cp cells. Annexin V-PI staining detected early apoptosis induced by CUR, DMC, and their combinations in both cell lines at 12 hours, with no necrosis observed. Gene expression analysis showed a significant decrease in GSTP-1 and miR-133b levels in A2780cp cells compared to A2780 cells. The combination treatments, particularly Cur+DMC+Cisplatin, synergistically reduced GSTP-1 and miR-133b expression. This study demonstrated the potential of CUR and DMC to enhance the efficacy of cisplatin in ovarian cancer treatment. The observed decrease in GSTP-1 and miR-133b expression in cisplatin-resistant cells suggests their involvement in drug resistance and highlights their potential as therapeutic targets.

Mechanism of ferroptosis resistance in cancer cells.

Ferroptosis is an iron-dependent cell death characterized by increased intracellular lipid peroxidation. Inducing ferroptosis has shown significant potential in eliminating various malignancies. However, the effectiveness of ferroptosis-based treatments is hampered by the intrinsic or acquired resistance of some tumors. In this review, we delineate the known mechanisms that regulate ferroptosis sensitivity and summarize the therapeutic application of ferroptosis inducers in cancer. Additionally, we discuss the roles of diverse signaling pathways that contribute to ferroptosis resistance in cancer cells, including the glutathione (GSH) and coenzyme Q (CoQ) pathways, NFE2-like bZIP transcription factor 2 (NRF2) antioxidant response, and lipid and iron metabolism. This emerging knowledge may serve as a foundation for developing novel anticancer strategies to overcome ferroptosis resistance.

CCRG-03. DETECTION OF HETEROGENEOUS CELL CYCLE ALTERATIONS UPON TMZ CHEMOTHERAPY TREATMENT THROUGH ADVANCED MACHINE LEARNING

Abstract Glioblastoma (GB), the most aggressive central nervous system tumor, is hallmarked by its frequent relapse under alkylating chemotherapy. GB cells frequently exhibit changes in cell cycle phases during TMZ treatment, with a reduction in the G0-G1 phase and an increase in the S and G2 phases. This indicate both tumor cell re-entry into the cell cycle and a TMZ-induced arrest, contributing to resistance and progression. In this study, we leverage dynamic protein abundance of Ki-67, a proliferation marker peaking during S, G2, and M phases, to analyse cellular responses to TMZ in various cell lines and tissue samples. We designed an image-based machine learning approach for pattern recognition to reconstruct and analyse the cell cycle at the single-cell level. Six primary cell lines were characterized through whole-genome DNA, methylation and RNA sequencing. Functional read-outs were performed with large-scale, time- and concentration-dependent TMZ treatments in cell culture and GB-tissue slice models. Our model successfully reconstructed detailed cell cycle stages, showing that untreated cells were predominantly in the G0-G1 phase. TMZ treatment significantly shifted cells toward the S/G2 phase (p < 0.02) in 3 of 6 cell lines and the pseudo-time reconstruction highlighted dose-dependent cell cycle changes. Cell lines with enhanced stem-like features, defined based on epigenetic and transcriptional data signature, showed no cell cycle changes at high TMZ doses (>150µM), regardless the MGMT promoter methylation status. This heterogeneity in cell cycle response emphasizes the complexity of GB and the need for personalized treatments. Our study provides insights into GB MGMT cell cycle alterations and resistance mechanisms that are independent of MGMT methylation status, a known TMZ response biomarker. Therefore, the observed TMZ-induced cell cycle changes may serve as novel biomarkers for assessing treatment response, paving the way for personalized therapeutic approaches.

Murine colon cancer derived cells exhibit heterogeneous resistance profiles against an oncolytic virus

Oncolytic virotherapy has shown efficacy in various animal models and a few human cancers. However, there are still significant limitations for the implementation of these therapies. One such limitation is the emergence of cellular resistances, which may appear rapidly considering the high genetic heterogeneity of most tumors. We previously showed that cellular resistance to an oncolytic virus can be mediated by the chronic activation of innate immunity. Here, we explored the existence of additional resistance mechanisms in murine colon cancer-derived cells. For this purpose, we isolated two cellular clones that were resistant to the oncolytic virus VSV-D51. While one of the clones showed a strong resistance profile associated with increased cytokine-mediated antiviral responses, the other clone showed a lower level of resistance that involves cytoskeletal reorganization, signaling by small GTPases, and cell structural changes. These results demonstrate the capacity of tumor cells to deploy heterogeneous mechanisms of resistance to oncolytic viruses.

Tackling Anticancer Drug Resistance and Endosomal Escape in Aggressive Brain Tumors Using Bioelectronics.

Resistance mechanisms in brain tumors, such as medulloblastoma and glioblastoma, frequently involve the entrapment of chemotherapeutic agents within endosomes and the extracellular expulsion of drugs. These barriers to effective treatment are exacerbated in nanotechnology-based drug delivery systems, where therapeutic nanoparticles often remain confined within endosomes, thus diminishing their therapeutic efficacy. Addressing this challenge necessitates the development of novel strategies to enhance the efficiency of cancer therapies. This study tests the hypothesis that external electrical stimuli can modulate intracellular trafficking of chemotherapeutic drugs in common malignant brain tumors in children (medulloblastoma) and adults (glioblastoma) by using gold nanoparticles (GNPs). In our experiments, alternating current (AC) stimulation ranging from 1 kHz to 5 MHz and at a strength of 1 V/cm significantly reduced cell viability in drug-resistant medulloblastoma and enhanced delivery of GNPs in glioblastoma. Low-frequency AC resulted in a 50% increase in apoptosis compared to controls and an 8-fold increase in cell death in cisplatin-resistant medulloblastoma cells, accompanied by a substantial reduction in EC50 from 2.5 to 0.3 μM. Similarly, vincristine-resistant cells demonstrated a 4-fold enhancement in drug sensitivity. Furthermore, high-frequency AC facilitated a significant increase from 20 to 75% in the endosomal escape of GNPs in glioblastoma cells. These findings underscore the potential of AC to selectively disrupt cancer cell resistance mechanisms and bolster the efficacy of nanoparticle-based therapies. The results indicate the effectiveness of AC stimulation in circumventing the limitations inherent in current nanotechnology-based drug delivery systems but also illustrates its transformative potential for treating aggressive, drug-resistant brain tumors.

Integrative Modeling of Signaling Network Dynamics Identifies Cell Type-Selective Therapeutic Strategies for FGFR4-Driven Cancers.

Oncogenic FGFR4 signaling represents a potential therapeutic target in various cancer types, including triple-negative breast cancer and hepatocellular carcinoma. However, resistance to FGFR4 single-agent therapy remains a major challenge, emphasizing the need for effective combinatorial treatments. Our study sought to develop a comprehensive computational model of FGFR4 signaling and to provide network-level insights into resistance mechanisms driven by signaling dynamics. An integrated approach, combining computational network modeling with experimental validation, uncovered potent AKT reactivation following FGFR4 targeting in triple-negative breast cancer cells. Analyzing the effects of cotargeting specific network nodes by systematically simulating the model predicted synergy of cotargeting FGFR4 and AKT or specific ErbB kinases, which was subsequently confirmed through experimental validation; however, cotargeting FGFR4 and PI3K was not synergistic. Protein expression data from hundreds of cancer cell lines was incorporated to adapt the model to diverse cellular contexts. This revealed that although AKT rebound was common, it was not a general phenomenon. For example, ERK reactivation occurred in certain cell types, including an FGFR4-driven hepatocellular carcinoma cell line, in which there is a synergistic effect of cotargeting FGFR4 and MEK but not AKT. In summary, this study offers key insights into drug-induced network remodeling and the role of protein expression heterogeneity in targeted therapy responses. These findings underscore the utility of computational network modeling for designing cell type-selective combination therapies and enhancing precision cancer treatment. Significance: Computational predictive modeling of signaling networks can decipher mechanisms of cancer cell resistance to targeted therapies and enable identification of more effective cancer type-specific combination treatment strategies.

Tumor Cell Spatial Organization Directs EGFR/RAS/RAF Pathway Primary Therapy Resistance through YAP Signaling.

Non-small cell lung cancers (NSCLC) harboring common mutations in EGFR and KRAS characteristically respond transiently to targeted therapies against those mutations, but invariably, tumors recur and progress. Resistance often emerges through mutations in the therapeutic target or activation of alternative signaling pathways. Mechanisms of acute tumor cell resistance to initial EGFR (EGFRi) or KRASG12C (G12Ci) pathway inhibition remain poorly understood. Our study reveals that acute response to EGFR/RAS/RAF-pathway inhibition is spatial and culture context specific. In vivo, EGFR mutant tumor xenografts shrink by > 90% following acute EGFRi therapy, and residual tumor cells are associated with dense stroma and have increased nuclear YAP. Interestingly, in vitro EGFRi induced cell cycle arrest in NSCLC cells grown in monolayer, while 3D spheroids preferentially die upon inhibitor treatment. We find differential YAP nuclear localization and activity, driven by the distinct culture conditions, as a common resistance mechanism for selective EGFR/KRAS/BRAF pathway therapies. Forced expression of the YAPS127A mutant partially protects cells from EGFR-mediated cell death in spheroid culture. These studies identify YAP activation in monolayer culture as a non-genetic mechanism of acute EGFR/KRAS/BRAF therapy resistance, highlighting that monolayer vs spheroid cell culture systems can model distinct stages of patient cancer progression.

Novel coumarin-6-sulfonamide-chalcone hybrids as glutathione transferase P1-1 inhibitors.

Multidrug resistance (MDR) mechanisms in cancer cells are greatly influenced by glutathione transferase P1-1 (hGSTP1-1). The use of synthetic or natural compounds as hGSTP1-1 inhibitors is considered an effective approach to overcome MDR. Nine compounds consisting of coumarin-6-sulfonamide linked to chalcone derivatives were synthesized and evaluated for their ability to inhibit hGSTP1-1. Among the synthetic derivatives, compounds 5g, 5f, and 5a displayed the most potent inhibitory effect, with IC50 values of 12.2 ± 0.5 μΜ, 12.7 ± 0.7 and 16.3 ± 0.6, respectively. Kinetic inhibition analysis of the most potent molecule, 5g, showed that it behaves as a mixed-type inhibitor of the target enzyme. An in vitro cytotoxicity assessment of 5a, 5f, and 5g against the human prostate cancer cell lines DU-145 and PC3, as well as the breast cancer cell line MCF-7, demonstrated that compound 5g exhibited the most pronounced cytotoxic effect on all tested cell lines. Molecular docking studies were performed to predict the structural and molecular determinants of 5g, 5f, and 5a binding to hGSTP1-1. In agreement with the experimental data, the results revealed that 5g exhibited the lowest docking score among the three studied inhibitors as a consequence of shape complementarity, governed by van der Waals, hydrogen bonds and a π-π stacking interaction. These findings suggest that coumarin-chalcone hybrids offer new perspectives for the development of safe and efficient natural product-based sensitizers that can target hGSTP1-1 for anticancer purposes.

Downregulation of Rad51 Expression and Activity Potentiates the Cytotoxic Effect of Osimertinib in Human Non-Small Cell Lung Cancer Cells.

Osimertinib (AZD9291) is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has shown significant clinical benefits in patients with EGFR-sensitizing mutations or the EGFR T790M mutation. The homologous recombination (HR) pathway is crucial for repairing DNA double-strand breaks (DSBs). Rad51 plays a central role in HR, facilitating the search for homology and promoting DNA strand exchange between homologous DNA molecules. Rad51 is overexpressed in numerous types of cancer cells. B02, a specific small molecule inhibitor of Rad51, inhibits the DNA strand exchange activity of Rad51. Previous studies have indicated that B02 disrupted Rad51 foci formation in response to DNA damage and inhibited DSBs repair in human cells and sensitized them to chemotherapeutic drugs in vitro and in vivo. However, the potential therapeutic effects of combining osimertinib with a Rad51 inhibitor are not well understood. The aim of this study was to elucidate whether the downregulation of Rad51 expression and activity can enhance the osimertinib-induced cytotoxicity in non-small cell lung cancer (NSCLC) cells. We used the MTS, trypan blue dye exclusion and colony-formation ability assay to determine whether osimertinib alone or in combination with B02 had cytotoxic effects on NSCLC cell lines. Real-time polymerase chain reaction was conducted to measure the amounts of Rad51 mRNA. The protein levels of phosphorylated AKT and Rad51 were determined by Western blot analysis. We found that osimertinib reduced Rad51 expression by inactivating AKT activity. Rad51 knockdown using small interfering RNA or AKT inactivation through the phosphatidylinositol 3-kinase inhibitor LY294002 or si-AKT RNA transfection enhanced the cytotoxic and growth inhibitory effects of osimertinib. In contrast, AKT-CA (a constitutively active form of AKT) vector-enforced expression could mitigate the cytotoxic and cell growth inhibitory effects of osimertinib. Furthermore, B02 significantly enhanced the cytotoxic and cell growth inhibitory effects of osimertinib in NSCLC cells. Compared to parental cells, the activation of AKT and Rad51 expression in osimertinib-resistant cells could not be significantly inhibited by osimertinib treatment. Moreover, the increased expression of Rad51 is associated with the resistance mechanism in osimertinib-resistant H1975 and A549 cells. Collectively, the downregulation of Rad51 expression and activity enhances the cytotoxic effect of osimertinib in human NSCLC cells.

Transport cocktails for cancer therapeutics

Beyond biological cell heterogeneity, evidenced by different resistances to therapeutics, “delivery heterogeneity” crucially limits treatment efficacy for advanced solid tumors: variations in therapeutic drug delivery to different tumor areas (perivascular, perinecrotic) leading to nonuniform drug concentrations/doses and to unsuccessful treatment (cancer cell kill). Short-range (40–80 µm), high energy (1–5 MeV) α particles successfully address the biological heterogeneity: the double-strand DNA breaks they cause make them impervious to cell resistance mechanisms. Multiresponsive nanocarriers and/or engineered antibody-drug-conjugates are elegant approaches to delivering such α-particle emitters. Delivery heterogeneity, however, remains a challenge in established (i.e., large, vascularized) tumors. Remarkably, delivery properties enabling efficacy at the cell scale (targeting selectivity, affinity, cell drug uptake) may act against spatial delivery uniformity at the tumor scale (binding-site barrier effect). We have previously demonstrated, in different mouse models, that spatial delivery uniformity, key to the effective killing of solid tumors, can be achieved utilizing combinations of different, distinct delivery carriers of the same emitter, but with different, complementary delivery properties, “leaving no cancer cell behind.” We build first principles reaction-transport models (quantitatively informed by experiments) that explain the “geographically complementary” behaviors of such carrier cocktails, and help optimally design these cocktails and their delivery protocols. Published by the American Physical Society 2024

Depolymerization of tubulin as the main molecular mechanism of the cytotoxic and antitumor activity of pyrrole-containing heterocyclic compounds

Introduction. Microtubules are highly dynamic polymers of α, β-tubulin dimers involves in a broad spectrum of the processes, such as intracellular transport and cell proliferation. This makes them an attractive molecular target for anti-cancer therapies. Substances that affect the dynamic state of tubulin microtubules are known as the mitotic poisons that are effectiveand widely used in the chemotherapy of various tumors. Mitotic poisons are able to interfere with polymerization (stabilization) or depolymerization of tubulin, which in turn leads to the arrest of cells in the M-phase (named as a mitotic catastrophe) and their subsequent death via activation of apoptotic mechanisms. However, the effectiveness of MP-based therapies is gradually decreasing over the time due to development of multiple drug resistance mechanisms in cancer cells. Thus, development of novel compounds selectively targeting tubulin and effectively overcoming multiple drugresistance phenotype in cancer is an urgent need in current oncology. Aim. To examine the cytotoxic and antitumor activities of several pyrrole-containing heterocyclic compounds (EPC-91, EPC-92 and PCA-93) against cancer cell lines with epithelial and mesenchymal origin, including those with multiple drug resistance phenotype. Materials and methods. Studies were performed on parental human cancer cell lines – triple-negative breast cancer HCC1806, gastrointestinal stromal tumor GIST T-1, osteosarcoma SaOS-2, – sensitive to chemotherapy (paclitaxel, doxorubicin) and their resistant sublines (HCC1806 Tx-R, GIST T-1 Tx-R, SaOS-2 Dox-R), as well as on murine colorectal adenocarcinoma cell line Colon-26, exhibiting primary resistance to the aforementioned chemotherapeutic agents. Results. The cytotoxic activities of EPC-91 and PCA-93 were due to their abilities to depolymerize tubulin. The results of immunofluorescence microscopy and Western blotting indicated that the compounds disrupt assembly of tubulin microtubules and prevent polymerization of α-tubulin in cancer cells. Inhibition of tubulin polymerizations led to significant increasein number of round-shaped and phospho-histone 3 (e. g. mitotic) cells, followed by their death through apoptosis. PCA-93 also exhibited potent anti-tumor effect against Colon-26 cells due to its anti-proliferative and proapoptotic activities. Conclusion. The data shown here illustrates potent cytotoxic activities of EPC-91 and PCA-93 against multiple cancer cell lines in vitro including those with multiple drug resistance phenotype. Similarly, PCA-93 was found to be highly effective against Colon-26 cell in vivo, thereby illustrating the attractive platform for the development of novel pyrrole-based agents exhibiting potent anti-tumor activities.

PAI-1 mediates acquired resistance to MET-targeted therapy in non-small cell lung cancer.

Mechanisms underlying primary and acquired resistance to MET tyrosine kinase inhibitors (TKIs) in managing non-small cell lung cancer remain unclear. In this study, we investigated the possible mechanisms acquired for crizotinib in MET-amplified lung carcinoma cell lines. Two MET-amplified lung cancer cell lines, EBC-1 and H1993, were established for acquired resistance to MET-TKI crizotinib and were functionally elucidated. Genomic and transcriptomic data were used to assess the factors contributing to the resistance mechanism, and the alterations hypothesized to confer resistance were validated. Multiple mechanisms underlie acquired resistance to crizotinib in MET-amplified lung cancer cell lines. In EBC-1-derived resistant cells, the overexpression of SERPINE1, the gene encoding plasminogen activator inhibitor-1 (PAI-1), mediated the drug resistance mechanism. Crizotinib resistance was addressed by combination therapy with a PAI-1 inhibitor and PAI-1 knockdown. Another mechanism of resistance in different subline cells of EBC-1 was evaluated as epithelial-to-mesenchymal transition with the upregulation of antiapoptotic proteins. In H1993-derived resistant cells, MEK inhibitors could be a potential therapeutic strategy for overcoming resistance with downstream mitogen-activated protein kinase pathway activation. In this study, we revealed the different mechanisms of acquired resistance to the MET inhibitor crizotinib with potential therapeutic application in patients with MET-amplified lung carcinoma.

Membrane Association of the Short Transglutaminase Type 2 Splice Variant (TG2-S) Modulates Cisplatin Resistance in a Human Hepatocellular Carcinoma (HepG2) Cell Line.

Hepatocellular carcinoma (HCC) is a heterogeneous malignancy with complex carcinogenesis. Although there has been significant progress in the treatment of HCC over the past decades, drug resistance to chemotherapy remains a major obstacle in its successful management. In this study, we were able to reduce chemoresistance in cisplatin-resistant HepG2 cells by either silencing the expression of transglutaminase type 2 (TG2) using siRNA or by the pre-treatment of cells with the TG2 enzyme inhibitor cystamine. Further analysis revealed that, whereas the full-length TG2 isoform (TG2-L) was almost completely cytoplasmic in its distribution, the majority of the short TG2 isoform (TG2-S) was membrane-associated in both parental and chemoresistant HepG2 cells. Following the induction of cisplatin toxicity in non-chemoresistant parental cells, TG2-S, together with cisplatin, quickly relocated to the cytosolic fraction. Conversely, no cytosolic relocalisation of TG2-S or nuclear accumulation cisplatin was observed, following the identical treatment of chemoresistant cells, where TG2-S remained predominantly membrane-associated. This suggests that the deficient subcellular relocalisation of TG2-S from membranous structures into the cytoplasm may limit the apoptic response to cisplatin toxicity in chemoresistant cells. Structural analysis of TG2 revealed the presence of binding motifs for interaction of TG2-S with the membrane scaffold protein LC3/LC3 homologue that could contribute to a novel mechanism of chemotherapeutic resistance in HepG2 cells.

Pan-cancer prognosis, immune infiltration, and drug resistance characterization of lung squamous cell carcinoma tumor microenvironment-related genes

BackgroundThe tumor microenvironment (TME) plays an important role in cancer development; however, its implications in lung squamous cell carcinoma (LUSC) and pan-cancer have been poorly understood. MethodsIn this study, The Cancer Genome Atlas (TCGA) and Estimation of Stromal and Immune cells in Malignant Tumor tissue using Expression Data (ESTIMATE) datasets were applied to identify differentially expressed genes. Additionally, online public databases were utilized for in-depth bioinformatics analysis of pan-cancer datasets to investigate the prognostic implications of TME-related genes further. ResultsOur study demonstrated a significant association between stromal scores, immune scores, and specific clinical characteristics in LUSC patients. C3AR1, CSF1R, CCL2, CCR1, and CD14 were identified as prognostic genes related to the TME. All TME-related prognostic genes demonstrated varying degrees of correlation with immune infiltration subtypes and tumor cell stemness. Moreover, our study revealed that TME-related prognostic genes, particularly C3AR1 and CCR1, might contribute to drug resistance in cancer cells. ConclusionsThe identified TME-related prognostic genes, particularly C3AR1 and CCR1, have potential implications for understanding and targeting drug resistance mechanisms in cancer cells.

Overcoming statin resistance in prostate cancer cells by targeting the 3-hydroxy-3-methylglutaryl-CoA-reductase

Prostate cancer is the most prevalent malignancy in men. While diagnostic and therapeutic interventions have substantially improved in recent years, disease relapse, treatment resistance, and metastasis remain significant contributors to prostate cancer-related mortality. Therefore, novel therapeutic approaches are needed. Statins are inhibitors of the 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway which plays an essential role in cholesterol homeostasis. Numerous preclinical studies have provided evidence for the pleiotropic antitumor effects of statins. However, results from clinical studies remain controversial and have shown substantial benefits to even no effects on human malignancies including prostate cancer. Potential statin resistance mechanisms of tumor cells may account for such discrepancies. In our study, we treated human prostate cancer cell lines (PC3, C4–2B, DU-145, LNCaP) with simvastatin, atorvastatin, and rosuvastatin. PC3 cells demonstrated high statin sensitivity, resulting in a significant loss of vitality and clonogenic potential (up to – 70%; p < 0.001) along with an activation of caspases (up to 4-fold; p < 0.001). In contrast, C4–2B and DU-145 cells were statin-resistant. Statin treatment induced a restorative feedback in statin-resistant C4–2B and DU-145 cells through upregulation of the HMGCR gene and protein expression (up to 3-folds; p < 0.01) and its transcription factor sterol-regulatory element binding protein 2 (SREBP-2). This feedback was absent in PC3 cells. Blocking the feedback using HMGCR-specific small-interfering (si)RNA, the SREBP-2 activation inhibitor dipyridamole or the HMGCR degrader SR12813 abolished statin resistance in C4–2B and DU-145 and induced significant activation of caspases by statin treatment (up to 10-fold; p < 0.001). Consistently, long-term treatment with sublethal concentrations of simvastatin established a stable statin resistance of a PC3SIM subclone accompanied by a significant upregulation of both baseline as well as post-statin HMGCR protein (gene expression up to 70-fold; p < 0.001). Importantly, the statin-resistant phenotype of PC3SIM cells was reversible by HMGCR-specific siRNA and dipyridamole. Our investigations reveal a key role of a restorative feedback driven by the HMGCR/SREBP-2 axis in statin resistance mechanisms of prostate cancer cells.

Exploration of drug resistance mechanisms in triple negative breast cancer cells using a microfluidic device and patient tissues

Chemoresistance is a major cause of treatment failure in many cancers. However, the life cycle of cancer cells as they respond to and survive environmental and therapeutic stress is understudied. In this study, we utilized a microfluidic device to induce the development of doxorubicin-resistant (DOXR) cells from triple negative breast cancer (TNBC) cells within 11 days by generating gradients of DOX and medium. In vivo chemoresistant xenograft models, an unbiased genome-wide transcriptome analysis, and a patient data/tissue analysis all showed that chemoresistance arose from failed epigenetic control of the nuclear protein-1 (NUPR1)/histone deacetylase 11 (HDAC11) axis, and high NUPR1 expression correlated with poor clinical outcomes. These results suggest that the chip can rapidly induce resistant cells that increase tumor heterogeneity and chemoresistance, highlighting the need for further studies on the epigenetic control of the NUPR1/HDAC11 axis in TNBC.