Drug-free Medium Research Articles

In vitro evaluation of the clinical utility of Apitolisib/Vorinostat combination in Apitolisib-resistant H1975 lung adenocarcinoma cells

BackgroundThe PI3K signalling pathway regulates the metabolic activity of cells. Disruption by PI3K inhibitors causes an aerobic/anaerobic imbalance that decreases energy production and cell growth. Cancer cells adapt to PI3K inhibitors in order to reduce their effectiveness. Resistance to Apitolisib could be due to intrinsic factors or acquired adaptation. Oncologists often ask whether to discontinue Apitolisib, increase its dose, or use a drug combination.MethodsWe observed the proliferation of resistant cells in (H1975R+) and out (H1975R−) of Apitolisib treatment, cell cycle pattern, energy phenotyping/reprogramming, and the effects of combining Apitolisib with Vorinostat on the acquired proliferation of H1975R− cells.ResultsThe Proliferation of H1975R− cells increased, while that of H1975R+ cells remained suppressed. Both conditions showed a 5 × decrease in the number of cells at the Go/G1 phase and doubled at S and G2/M phases (p < 0.0001). Both H1975R− and H1975R+ cells exhibited decreased ECAR, with a stronger effect observed in H1975R+ cells (p < 0.0001). Oxygen consumption (OCR) increased significantly in H1975R− compared with that in H1975P (p = 0.02). The resistant cells became energetically active using mitochondrial respiration in drug-free medium; H1975R+ was hypo-energetic and consumed more free fatty acids (p = 0.0001). Ketone bodies in H1975R+ were increased by 40% and 2 × in BOHB and AcAc levels, respectively, compared to that in H1975P and H1975R− (p < 0.0001). H1975R− cell survival was 80% compared with 20% in H975R+ cells treated with 7 μM Vorinostat. Vorinostat effectively controlled acquired hyperproliferation of H1975R− cells.ConclusionIf a tumour becomes unresponsive to Apitolisib, it is advisable to continue the inhibitor and consider a combination with non-tyrosine kinase inhibitors.

CB-839 induces reversible dormancy in lung tumor-cells

Glutaminase inhibitors are currently being explored as potential treatments for cancer. This study aimed to elucidate the molecular mechanisms underlying the effects of CB-839 on lung tumor cell lines compared to non-tumor cell lines. Viability assays based on NADPH-dependent dehydrogenases activity, ATP energy production, or mitochondrial reductase activity were used to determine that CB-839 caused significant tumor cell specific inhibition of cellular functions. Clonogenic survival assay revealed a dose dependent reduction in clonogenic survival of various lung tumor cells presenting estimated IC50 values between 10 and 90 nM, while no effect on non-tumor cells was observed. CB-839 led to a 20% reduction in glutaminase (GLS1, a mitochondrial enzyme that catalyzes the conversion of glutamine to glutamate) activity, and a dose-dependent reduced glutamine consumption in tumor cells and had no effect on non-tumor cells. Cell cycle analysis showed the CB-839 did not lead to cell cycle arrest. Apoptosis and necrosis assays revealed an only slight increase in apoptosis in tumor cells. Furthermore, a trypan blue exclusion assay revealed about 40% growth reduction in tumor cells at 0.1–1 μM CB-839 treatment. Surprisingly, treated cells resumed normal growth when re-plated in a drug-free medium, demonstrating reversibility. In hypoxic conditions, CB-839's effect on clonogenic survival was amplified in a dose dependent manner consistent with increased role of GLS1 for energy production under hypoxic conditions. In conclusion, these results suggest CB-839 efficacy is linked to temporary and reversible reduction in glutamine utilization suggesting induction of dormancy.

An investigation of the dose-dependent safety of bemiparin sodium: A cell culture study

Aim: Fibroblasts are common cells in subcutaneous tissue and they have an important role on healing process. Although patients who are receiving first-generation low molecular weight heparins are more likely to experience skin responses, there is no study evaluating the effect of bemiparin sodium on subcutaneous fibroblasts following administration. In the present study, we aimed to evaluate the effects of bemiparin sodium on fibroblast cell viability in cell culture model. Material and Methods: The L929 cells were incubated for 12 hours in 96-well culture dishes. Fresh medium containing different concentrations of bemiparin was added in five different concentrations (Dilution I: 3,500 IU; Dilution II: 1,750 IU; Dilution III: 875 IU; Dilution IV: 437.5 IU; Dilution V: 218.75 IU). A control group was established with drug-free culture medium. Cell viability analysis was performed after 48 hours of incubation by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. The change in cell morphology was examined at each dilution by direct and acridine orange/propidium iodide staining. Results: The highest cytotoxic effect was observed in dilution I compared to the control group (p&lt;0.05). There is a clear deviation from the fibroblastic morphology of the cells in dilution I. The cells have a round morphology with degeneration and nuclear condensation. Conclusion: Although it seems that high doses of bemiparin may have a negative effect on fibroblast cells in subcutaneous tissue, it can be considered that the cytotoxic effects of high concentrations of the drug at the application site will not be clinically significant due to using a single dose per day.

Influence of the agrochemical benomyl on Cryptococcus gattii-plant interaction in vitro and in vivo.

Cryptococcus gattii, an environmental fungus, is one of the agents of cryptococcosis. The influence of agrochemicals on fungal resistance to antifungals is widely discussed. However, the effects of benomyl (BEN) on fungal interaction with different hosts is still to be understood. Here we studied the influence of adaptation to BEN in the interaction with a plant model, phagocytes and with Tenebrio molitor. First, the strain C. gattii L24/01 non-adapted (NA), adapted (A) to BEN, and adapted with further culture on drug-free media (10p) interact with Nicotiana benthamiana, with a peak in the yeast burden on the 7th day post-inoculation. C. gattii L24/01 A and 10p provided lower fungal burden, but these strains increased cell diameter and capsular thickness after the interaction, together with decreased fungal growth. The strains NA and A showed reduced ergosterol levels, while 10p exhibited increased activity of laccase and urease. L24/01 A recovered from N. benthamiana was less engulfed by murine macrophages, with lower production of reactive oxygen species. This phenotype was accompanied by increased ability of this strain to grow inside macrophages. Otherwise, L24/01 A showed reduced virulence in the T. molitor larvae model. Here, we demonstrate that the exposure to BEN, and interaction with plants interfere in the morphophysiology and virulence of the C. gattii.

Abstract 235: Application of high-grade serous ovarian cancer organoids in functional precision medicine

Abstract High-grade serous ovarian cancer (HGSC) is the most frequent and lethal ovarian cancer type. Despite responding favorably to first-line therapy, most HGSC patients eventually relapse. HGSC is characterized by high interpatient genomic heterogeneity and few recurrent mutations that could be used as therapeutic biomarkers. Thus, except the introduction of PARP inhibitors for BRCA1/2-mutated patients, there has been little progress with personalizing HGSC treatment. Functional precision medicine - tailoring personalized therapies based on functional assays on patient-derived cells - has been applied in cancer clinical trials to address this issue. Organoids - three-dimensional cell cultures, recapitulating aspects of original tumors’ structure and function - have often been used as models in these efforts. However, inefficient and time-consuming organoid derivation protocols have been hindering the application of HGSC organoids in functional precision medicine clinical trials, due to the short time during which the therapy must be selected. To address this, we here aimed to establish whether we could predict second-line therapy drug sensitivities in relapsed HGSC using organoids from tumor material from first-line therapy. We have previously derived a collection of 23 organoid models from 16 patients, sampled sequentially at different times of their treatment (1). Here, for several organoid primary-relapse pairs, we performed drug screens using a library of 370 compounds (approved, in clinical development or tool compounds). We found that 90% of the hit compounds in the primary organoids also were hits in the matched relapse-derived organoid models. In several patients, we observed a pronounced cytotoxicity of several cyclin-dependent kinase (CDK) inhibitors, all of which potently inhibit CDK9, including two selective inhibitors (AZD4573 and VIP152) in clinical development. Screening of CDK9 inhibitors in an extended panel of organoid models revealed that most organoids are sensitive to CDK9 inhibition in nanomolar range. CDK9 inhibitors also prevented organoid outgrowth in long-term culture (&amp;gt;1.5 month) in drug-free medium. Taken together, we demonstrate that HGSC organoids from material sampled during first-line treatment predict most drug sensitivities of relapse-derived organoids. This suggests a feasibility of functional precision approach for selection of second-line therapy using only primary tumor material, circumventing the problem of limited time available for the therapy choice after tumor sampling. This work also highlights that CDK9 inhibitors, currently in clinical development for hematological malignancies, are worthwhile to be explored in HGSC. 1. Senkowski et al. A platform for efficient establishment and drug-response profiling of high-grade serous ovarian cancer organoids. Developmental Cell (2023) Citation Format: Wojciech Senkowski, Laura Gall-Mas, Matias M. Falco, Yilin Li, Kari Lavikka, Aura Crispino, Jaana Oikkonen, Daria Bulanova, Yan-Jun Chen, Elena M. Doncel, Karolin Voßgröne, Erdogan P. Erkan, Jun Dai, Anastasia Lundgren, Jutta Huvila, Kaisa Huhtinen, Johanna Hynninen, Sampsa Hautaniemi, Anna Vähärautio, Krister Wennerberg. Application of high-grade serous ovarian cancer organoids in functional precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 235.

Abstract 2148: Tumor-microenvironment from African-American prostate cancer exhibit methylation of multiple immune modulators

Abstract Background: Non-Hispanic Black American patients (BA) with prostate cancer (PCa) tend to fare worse than their Non-Hispanic White American counterparts (WA), even with consideration of socioeconomic disparities. Clinically, BA face diagnosis at younger age with worse clinical outcomes. Stromal cells adjacent to the tumor, including carcinoma-associated fibroblasts (CAFs), play a critical role in tumorigenesis of PCa. Dysfunction in the tumor microenvironment play a crucial role in mediating prostate cancer tumorigenesis and is emerging as a key target for cancer therapy in solid tumors. Methods: To investigate whether DNA methylation varies in tumor adjacent stroma (TAS) among PCa patients with different geographical ancestries, areas immediate adjacent to tumor (i.e., less than 1mm) removed for methylation analysis. A complete genome-wide DNA methylation of PCa stroma using 17 BA and 15 WA patients who had radical prostatectomy was carried out. Methyl-Captured (mCap) sequencing data was generated for TAS of prostate cancer FFPE tissues. Methylated sites were identified with the MACS2 callpeak function using a band width of 300 bp and a false discovery rate of q &amp;lt; 0.05. A consensus peak set was derived from the aligned reads of BA and WA prostate cancer stroma samples that were sequenced. Pathway analysis was performed using Ingenuity Pathway Analysis (IPA) tools. CAFs from primary tumors of BA and WA was prepared by tissue culture and treated with demethylating agent (i.e., 5-Azacytidine) for 24 hours followed by maintenance of the cells in drug-free medium for 7-10 days and subjected to mCap sequencing. Results: We found racial disparities in genome-wide DNA methylation in TAS between the two populations in which BA PCa patients had significantly increased in global DNA methylation as compared to their WA counterpart (p value &amp;lt; 0.001). Hypomethylation occurred in CAFs from BA patients treated with 5-Azacytidine. We identified 1041 methylated sites corresponding to 409 unique genes that were differentially methylated in BA vs WA (p value &amp;lt; 0.05). Pathway analysis identified significant association between methylated genes in BA TAS and immune response pathways including IL-13, JACK/STAT, T cell receptors, NF-KB, and PD-1, PDL1 cancer immunotherapy. Evaluation of the methylome profile between patients based on the post-prostatectomy resection margins, negative (R0) vs positive (R1), showed that R0 resections had significantly greater (p value &amp;lt; 0.001) methylation than R1 resections. Further analysis identified 984 sites corresponding to 373 differentially methylated, unique genes (p value &amp;lt; 0.05). Conclusion: Tumor-adjacent stroma of BA prostate cancer patients has a distinct methylome as compared to WA patients. Differences in immune response pathways suggests a distinct immune response in TAS in men of different races. Citation Format: Santosh Sankaran, James Nguyen, Tara Jennings, Vinay Kumar, Michael B. Lilly, Michael M. Ittmann, Patricia Castro, Liankun Song, Thomas Keane, Weiping Chu, Xiaolin Zi, Omid Yazdanpanah, Arash Rezazadeh Kalebasty, Farah Rahmatpanah. Tumor-microenvironment from African-American prostate cancer exhibit methylation of multiple immune modulators [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2148.

The Resistance Mechanism to BET-Protac in Multiple Myeloma

Objective ：Explore the resistance mechanism of BET protein degradation targeting chimera (BET-PROTAC) in multiple myeloma (MM) cells, and find strategies to enhance the efficacy of BET-PROTAC. So as to provide new theoretical basis for the treatment of multiple myeloma. Methods ：The changes of TCF7 and c-Myc mRNA level were detected by RT-qPCR after BET-PROTAC (ARV-771) treatment of RPMI-8226 cells, the transcriptional activity of β-catenin in ARV-771 tolerant cells was detected by double luciferase reporter assay. Constructing lentiCRISPR-v2 vector to knockout β-catenin in RPMI-8226 cells, and detecting the sensitivity changes to ARV-771 and the formation of drug-resistant clones; MM cell lines resistant to ARV-771 were induced by dose escalation method, and detect the sensitivity of drug-resistant cells to other BET inhibitors and anti-tumor drugs; RNA-seq was used to detect the significantly changed genes and signal modules in drug-resistant cells, and verify this in drug-resistant cells; The drug resistant cells were treated with inhibitors or knockout the resistance gene to observe whether the drug resistance was reversible; The CRISPR knockout gene library was used to screen the candidate genes related to the up-regulation of drug resistance genes in drug-resistant cells, the expression of candidate genes was interfered, and the expression of drug resistance proteins was detected. The correlation between these candidate genes and the prognosis of MM patients was analyzed through public databases. Results ： In ARV-771 tolerant RPMI-8226 cells, the mRNA expression of TCF7 was significantly elevated, but the expression of c-Myc was still at a low level. TOPFlash assay showed activation of β-catenin signal in tolerant cells; Knockout of β-catenin in RPMI-8226 cells by CRISPR/cas9 increased apoptosis induced by ARV-771. Colony formation assay showed that there was no significant difference in the formation rate and number of drug-resistant clones after β-catenin knockout. ARV-771 resistant RPMI-8226 cells were successfully induced by dose increasing method, and three drug-resistant clones (AR1, AR2 and AR3) were obtained, the IC50 of these cells were 80, 120 and 8 times higher than the parental cells, respectively. The drug-resistant cells were cultured in drug-free medium for another 6 months, but the sensitivity did not recover. AR1 and AR2 cells showed decreased sensitivity to ARV-825, MZ-1, OTX-015, I-BET151, Daunorubicin and Epirubicin. RNA-seq showed that ABCB1 was significantly up-regulated in drug-resistant cells, and we verified the up-regulation of ABCB1 at mRNA and protein levels in all drug-resistant cells. Combined use of ABCB1 inhibitors (verapamil, cyclosporin A, Elacridar) or knockout of ABCB1 could significantly reduce the IC50 of drug-resistant cells, increase the apoptosis rate after ARV-771 treatment, and increase the degradation of BRD4 and the down-regulation of c-Myc. Using CRISPR/Cas9 library screening technology, we preliminarily selected 39 genes that may be involved in the regulation of ABCB1 expression, among which the downregulation of 14 genes could reduce the protein expression of ABCB1 in drug-resistant cells. Further through public databases, we found that C1orf112, CCDC167 and CRIP2 are significantly correlated with the prognosis of myeloma patients and are highly expressed in a variety of tumor tissues. These three genes will be the focus of subsequent studies. Conclusions ：Our results showed that BET-PROTAC resistance in MM cells wasindependent of β-catenin activation. The up-regulation of ABCB1 expression was the key mechanism mediating the resistance of myeloma cells to BET-PROTAC. C1orf112, CCDC167 and CRIP2 might be associated with drug resistance in myeloma and could affect prognosis, and their mechanisms in myeloma need to be further investigated. Keywords ：Multiple myeloma; BET; Protein degradation targeting chimera; Drug resistance; CRISPR library; ABCB1

Cross-feeding affects the target of resistance evolution to an antifungal drug.

Pathogenic fungi are a cause of growing concern. Developing an efficient and safe antifungal is challenging because of the similar biological properties of fungal and host cells. Consequently, there is an urgent need to better understand the mechanisms underlying antifungal resistance to prolong the efficacy of current molecules. A major step in this direction would be to be able to predict or even prevent the acquisition of resistance. We leverage the power of experimental evolution to quantify the diversity of paths to resistance to the antifungal 5-fluorocytosine (5-FC), commercially known as flucytosine. We generated hundreds of independent 5-FC resistant mutants derived from two genetic backgrounds from wild isolates of Saccharomyces cerevisiae. Through automated pin-spotting, whole-genome and amplicon sequencing, we identified the most likely causes of resistance for most strains. Approximately a third of all resistant mutants evolved resistance through a pleiotropic drug response, a potentially novel mechanism in response to 5-FC, marked by cross-resistance to fluconazole. These cross-resistant mutants are characterized by a loss of respiration and a strong tradeoff in drug-free media. For the majority of the remaining two thirds, resistance was acquired through loss-of-function mutations in FUR1, which encodes an important enzyme in the metabolism of 5-FC. We describe conditions in which mutations affecting this particular step of the metabolic pathway are favored over known resistance mutations affecting a step upstream, such as the well-known target cytosine deaminase encoded by FCY1. This observation suggests that ecological interactions may dictate the identity of resistance hotspots.

Establishment and Molecular Characterization of an In Vitro Model for PARPi-Resistant Ovarian Cancer.

Overcoming PARPi resistance is a high clinical priority. We established and characterized comparative in vitro models of acquired PARPi resistance, derived from either a BRCA1-proficient or BRCA1-deficient isogenic background by long-term exposure to olaparib. While parental cell lines already exhibited a certain level of intrinsic activity of multidrug resistance (MDR) proteins, resulting PARPi-resistant cells from both models further converted toward MDR. In both models, the PARPi-resistant phenotype was shaped by (i) cross-resistance to other PARPis (ii) impaired susceptibility toward the formation of DNA-platinum adducts upon exposure to cisplatin, which could be reverted by the drug efflux inhibitors verapamil or diphenhydramine, and (iii) reduced PARP-trapping activity. However, the signature and activity of ABC-transporter expression and the cross-resistance spectra to other chemotherapeutic drugs considerably diverged between the BRCA1-proficient vs. BRCA1-deficient models. Using dual-fluorescence co-culture experiments, we observed that PARPi-resistant cells had a competitive disadvantage over PARPi-sensitive cells in a drug-free medium. However, they rapidly gained clonal dominance under olaparib selection pressure, which could be mitigated by the MRP1 inhibitor MK-751. Conclusively, we present a well-characterized in vitro model, which could be instrumental in dissecting mechanisms of PARPi resistance from HR-proficient vs. HR-deficient background and in studying clonal dynamics of PARPi-resistant cells in response to experimental drugs, such as novel olaparib-sensitizers.

Aneuploidy Formation in the Filamentous Fungus Aspergillus flavus in Response to Azole Stress.

Aspergillus flavus is a mycotoxigenic fungus that contaminates many important agricultural crops with aflatoxin B1, the most toxic and carcinogenic natural compound. This fungus is also the second leading cause of human invasive aspergillosis, after Aspergillus fumigatus, a disease that is particularly prevalent in immunocompromised individuals. Azole drugs are considered the most effective compounds in controlling Aspergillus infections both in clinical and agricultural settings. Emergence of azole resistance in Aspergillus spp. is typically associated with point mutations in cyp51 orthologs that encode lanosterol 14α-demethylase, a component of the ergosterol biosynthesis pathway that is also the target of azoles. We hypothesized that alternative molecular mechanisms are also responsible for acquisition of azole resistance in filamentous fungi. We found that an aflatoxin-producing A. flavus strain adapted to voriconazole exposure at levels above the MIC through whole or segmental aneuploidy of specific chromosomes. We confirm a complete duplication of chromosome 8 in two sequentially isolated clones and a segmental duplication of chromosome 3 in another clone, emphasizing the potential diversity of aneuploidy-mediated resistance mechanisms. The plasticity of aneuploidy-mediated resistance was evidenced by the ability of voriconazole-resistant clones to revert to their original level of azole susceptibility following repeated transfers on drug-free media. This study provides new insights into mechanisms of azole resistance in a filamentous fungus. IMPORTANCE Fungal pathogens cause human disease and threaten global food security by contaminating crops with toxins (mycotoxins). Aspergillus flavus is an opportunistic mycotoxigenic fungus that causes invasive and noninvasive aspergillosis, diseases with high rates of mortality in immunocompromised individuals. Additionally, this fungus contaminates most major crops with the notorious carcinogen, aflatoxin. Voriconazole is the drug of choice to treat infections caused by Aspergillus spp. Although azole resistance mechanisms have been well characterized in clinical isolates of Aspergillus fumigatus, the molecular basis of azole resistance in A. flavus remains unclear. Whole-genome sequencing of eight voriconazole-resistant isolates revealed that, among other factors, A. flavus adapts to high concentrations of voriconazole by duplication of specific chromosomes (i.e., aneuploidy). Our discovery of aneuploidy-mediated resistance in a filamentous fungus represents a paradigm shift, as this type of resistance was previously thought to occur only in yeasts. This observation provides the first experimental evidence of aneuploidy-mediated azole resistance in the filamentous fungus A. flavus.

An In-House-Built and Light-Emitting-Diode-Based Photodynamic Therapy Device for Enhancing Verteporfin Cytotoxicity in a 2D Cell Culture Model

This paper describes a novel, simple, and low-cost device to perform in vitro photodynamic therapy (PDT) assays, named the PhotoACT. The device was built using a set of conventional programmable light-emitting diodes (LEDs), a liquid crystal display (LCD) module, and a light sensor connected to a commercial microcontroller board. The box-based structure of the prototype was made with medium-density fiberboards (MDFs). The internal compartment can simultaneously allocate four cell culture multiwell microplates. As a proof of concept, we studied the cytotoxic effect of the photosensitizer (PS) verteporfin against the HeLa cell line in two-dimensional (2D) culture. HeLa cells were treated with increasing concentrations of verteporfin for 24 h. The drug-containing supernatant medium was discarded, the adherent cells were washed with phosphate-buffered saline (PBS), and drug-free medium was added. In this study, the effect of verteporfin on cells was examined either without light exposure or after exposure for 1 h to light using red-green-blue (RGB) values of 255, 255, and 255 (average fluence of 49.1 ± 0.6 J/cm2). After 24 h, the cell viability was assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. Experimental results showed that exposure of cells treated with verteporfin to the light from the device enhances the drug's cytotoxic effect via a mechanism mediated by reactive oxygen species (ROS). In addition, the use of the prototype described in this work was validated by comparing the results with a commercial PDT device. Thus, this LED-based photodynamic therapy prototype represents a good alternative for in vitro studies of PDT.

Establishment and Characterization of Single and Triple‐Agent Resistant Osteosarcoma Cell Lines

Two human osteosarcoma cell lines (MG-63 and HOS-143B) are developed into drug-resistant models using a short-term drug exposure and recovery in drug-free media. Cisplatin, doxorubicin, and methotrexate are used as single agents and in triple combination. The highest level of resistance to cisplatin is observed in MG-63/CISR8, doxorubicin in HOS-143B/DOXR8, and methotrexate in HOS-143B/MTXR8. The MG-63/TRIR8 and HOS-143B/TRIR8 triple-resistance models show lower levels of resistance to combination treatment and are not resistant to the drugs individually. Apoptosis assays suggest that the resistance in MG-63/TRIR8 isfrom cisplatin and methotrexate and not doxorubicin. In contrast, the resistance in HOS-143B/TRIR8 is from doxorubicin and methotrexate instead of cisplatin. Upregulation of P-glycoprotein is seen in all resistant models except those developed with single-agent methotrexate. However, P-glycoprotein is not causing resistance in all cell lines as the inhibitor elacridar only reverses the resistance of doxorubicin on MG-63/DOXR8 and HOS-143B/TRIR8. The migration of the MG-63 resistant models is significantly increased, their invasion rate tends to increase, and RT-PCR shows a switch from epithelial to mesenchymal gene signaling. In contrast, a significant decrease in migration is seen in HOS-143B resistant models with their invasion rate tending to decrease and a switch from mesenchymal to epithelial gene signaling.

Abstract 5380: Anticancer compound ONC201 induces prolonged stress and arrest of proliferation in BT474 human breast cancer cells without induction of cell death

Abstract Background and goals: ONC201 an experimental anticancer drug, targeting mitochondrial caseinolytic peptidase, ClpP is currently under investigation. Current data on the effect of ONC201 along with observations that ONC201 causes cytotoxic effect, there are data demonstrating that ONC201 is rather cytostatic and does not induce cell death. Recently, we demonstrated ONC201-induced arrest of proliferation and a decrease in the number of mitochondrial nucleoids. Here we extended our study to describe the effect of short-and long-term exposure of BT474 cells to ONC201. Observations: Proliferation and cell cycle arrest. ONC201 in a dose-dependent manner (0-50 µM) inhibited the proliferation of BT474 cells without induction of apoptotic cell death. Cells exposed to 10 µM ONC201 accumulated in G0/G1 phase (49.4 ± 11.5% vs 78.7 ± 5.1%) and declined in the S-phase of the cell cycle (39.2 ± 6.6% vs 9.0 ± 2.1%). In parallel, ONC201 exposure induced a decline in Cyclin E and Cdk2 protein levels. Nucleoids and mtDNA. Exposure of BT474 cells, to 10 µM ONC 201, decreased the number of mitochondrial nucleoids from 249 ± 52 to 155 ± 38 per cell after 24 h. Longer 72 h exposure further reduced the number of nucleoids to 84 ± 36 per cell. ONC201 exposure also induced reduction of mitochondrial size from 2.8 ± 0.5 µm2 to 1.5 ± 0.2 µm2 and depletion of mtDNA. Short-term and long-term consequences of cell exposure to ONC201. Short-term treatment (24 h exposure) demonstrated the reversible effect of ONC201 on the expression of stress proteins (ATF4, CHOP, and GDF-15), cell cycle regulatory proteins (cyclin E, Cdk2), and partial restoration of mitochondrial nucleoids (to 214 ± 46 nucleoids per cell). On the contrary, long-term treatment (72 h) resulted in the irreversible and persistent arrest of proliferation, decline of cell cycle regulatory proteins, and activation of stress proteins. Respiration. ONC201 exposure suppressed State 3, State 4, and uncoupled respiration in digitonin-permeabilized BT474 cells. Complex I activity was decreased from 3.3 ± 0.4 ng-atoms O/min/106 cells to 0.5 ± 0.1 and 0.4 ± 0.3 ng-atoms O/min/106 cells, in cells exposed to ONC201 for 24h and 72h, respectively. Similarly, ONC201 decreased the activity of Complex II from 3.5 ± 0.5 ng-atoms O/min/106 cells to 1.5 ± 0.6 and 0.3 ± 0.1 ng-atoms O/min/106. Conclusions: The consequences of ONC201 treatment were dependent on the duration of exposure to the drug. Short-term (24 h) exposure of BT474 cells resulted in reversible induction of stress proteins (ATF4, CHOP, and GDF-15), which were reversed following 120 h incubation in drug-free media. On the contrary, long-term (72 h) exposure of cells to ONC201 induced irreversible and persistent arrest of proliferation and elevation of expression of stress proteins. Thus, ONC201 can induce prolonged and irreversible elevation of stress proteins and persistent G1/S cell cycle arrest. Citation Format: Artem A. Mishukov, Irina V. Odinokova, Serazhutdin A. Abdullaev, Vitaly K. Zhalimov, Emily M. Fennel, Lucas J. Aponte-Collazo, Paul R. Graves, Lee M. Graves, Ekhson L. Holmuhamedov. Anticancer compound ONC201 induces prolonged stress and arrest of proliferation in BT474 human breast cancer cells without induction of cell death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5380.

Epigenetic drugs induce the potency of classic chemotherapy, suppress post-treatment re-growth of breast cancer, but preserve the wound healing ability of stem cells

ABSTRACT Epigenetic therapy augments neoadjuvant chemotherapy (NACT) in breast cancer and may aid post-surgical wound healing affected by NACT. Our study investigates: (1) The cytotoxicity of classic paclitaxel chemotherapy on triple negative breast cancer (TNBC) independently and in combination with epigenetic drugs. (2) The sustainable inhibition of breast cancer regrowth following paclitaxel and epigenetic therapies. (3) The effects of paclitaxel with and without epigenetic therapy on the post-treatment viability and wound healing potential of adipose stem cells (ASCs). Cytotoxicity assays were performed on TNBC and ASCs. Cells were treated and recovered in drug-free medium. Cell viability was measured via cell counts and MTT assays. W -ound healing was tested with scratch assays. The combination of epigenetic drugs shows increased toxicity against TNBC cells compared to standard chemotherapy alone. Moreover, the combination of paclitaxel with epigenetic treatments causes cancer toxicity that is sustainable to TNBC cells after the drugs’ removal with minimal effect on ASCs wound healing ability. The use of epigenetic drugs in addition to standard chemotherapy is cytotoxic to TNBC cells and prevents post-treatment recovery of TNBC while maintaining ASC wound healing ability. This strategy may be useful in maximizing post-surgical wound healing following NACT in TNBC.

Abstract 2048: Property analysis of chromosomal instability-adapted cells using multi-omics approaches

Abstract Background: Chromosomal instability (CIN), which includes polyploidy and aneuploidy, is characterized as the pillar of cancer hallmarks. CIN is observed in &amp;gt;90% solid tumors, being correlated with malignancy grades, poor prognosis, and drug resistance. However, it is still unclear yet how aneuploidy triggers cancer initiation/progression, or how aneuploidy gives negative impacts on cancer therapeutics. In this study, we established our original CIN cell line model, aiming to understand biological significance of cancer aneuploidy on the CIN-mediated stress adaptation.Method: A colorectal cancer cell, HCT116, was treated with an Aurora-B kinase inhibitor for 24 hours to transiently induce CIN in these cells, and then cultured in a drug-free medium for &amp;gt;10 days to establish “CIN-adapted cells”. Cell growth was evaluated by intracellular ATP concentrations. RNAs and DNAs extracted from the cells were subjected to RNA-seq, Exome-seq, and ATAC-seq by the NovaSeq sequencing systems. The cell lysates were subjected to metabolomics analyses by GC-MS system. Bioinformatics analyses were performed using these multiple-omics data.Results: In 10 days after aneuploid formation, 90% aneuploid cells were killed, while 10% aneuploid cells were proliferative with a high growth rate equivalent to that of the parental euploid cells, which appeared to overcome the CIN-mediated antiproliferative pressure. The CIN-adapted cells revealed to be highly sensitive to the low-glucose and hypoxic condition, suggesting that the metabolic pathways would be modulated to adjust the cells to the aneuploid-mediated stress. Transcriptome and metabolome analyses also revealed the gene expressions and the metabolites for the lipid or amino acids metabolisms were significantly changed in the CIN-adapted cells. These findings suggest that the CIN-adapted cells appear to restructure their signaling networks of the lipid and amino acid metabolic pathways, which is expected to play important roles for the aneuploid cells to survive under the CIN-mediated stress. We perform drug screening to identify essential factors in the process leading to CIN-adapted, aiming for a comprehensive understanding of the molecular mechanism and signal networks.Conclusions: We comprehensively characterized the CIN-adapted cancer cell model by the multi-omics approaches. These findings will help us to deeply understand the biological significance of CIN in cancer cells, providing a new insight to novel cancer therapeutics targeting CIN. Citation Format: Tomoko Yamamori Morita, Hiroshi Haeno, Hideki Makinoshima, Ayako Suzuki, Susumu S. Kobayashi, Akihiro Ohashi. Property analysis of chromosomal instability-adapted cells using multi-omics approaches [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 2048.

Antigen presentation capability and AP-1 activation accompany methotrexate-induced colon cancer cell senescence in the context of aberrant β-catenin signaling

Reversible cellular senescence was demonstrated previously to constitute colon cancer cell response to methotrexate. The current study presents a comparison of two senescent states of colon cancer cells, arrested and reversing, resulting from respectively, 120 h exposure to the drug, and 48 h exposure followed by 96 h regrowth in drug-free media. The upregulation of immunoproteasome subunit-coding genes and the increase in human leukocyte antigen HLA-A/B/C membrane level indicated MHC-I-restricted antigen presentation as common to both senescent states. Nuclear factor NF-κB p65 level decreased and activating protein AP-1: c-Jun, Fra2 and JunB nuclear levels increased in both senescent cell populations. Notably, the increase in AP-1- dependent transcription occurred after 48 h exposure to methotrexate. β-catenin nuclear level increased after 48 h exposure to the drug and remained as such only in senescence-arrested cells. β-catenin level was found uncoupled from the protein phosphorylation status indicating the deregulation of β-catenin signaling in colon cancer cells employed in the study. These findings carry implications for both, a general mechanism of senescence establishment and putative advantages for colon cancer treatment.

Abstract PO-014: 3-Aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP): A promising radiochemotherapy for gastroenteropancreatic neuroendocrine tumors

Abstract Background: Peptide receptor radionuclide therapy (PRRT) is a novel radiotherapy approved for gastroenteropancreatic neuroendocrine tumors (GEP-NETs); however, PRRT has a relatively low treatment response rate of 20-30%. We hypothesize that addition of 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP), a ribonucleotide reductase (RnR) inhibitor that inhibits the rate-limiting enzyme of DNA synthesis and repair, can improve radiotherapy outcomes. The purpose of this study is to determine the therapeutic rationale of RnR-targeted therapy and evaluate 3-AP as a radiosensitizer in treating GEP-NET in vitro and in vivo. Methods: We utilized two human GEP-NET cell lines: BON, a pancreatic carcinoid tumor, and QGP-1, a somatostatinoma. (i) Cells were treated with 3-AP for 96h and cell proliferation assays were performed using a sulforhodamine B (SRB) kit. Next, cells were treated with 3-AP for 24, 48, 72, 96h and cell cycle analyses were performed with Beckman Coulter cell cycle kit and quantified by flow cytometry. Expression of cell cycle arrest markers (i.e., pCdk-1, cyclin D1) was assessed by immunoblotting. (ii) To determine radiosensitivity in vitro, cells were treated with 3-AP for 16h, followed by X-ray radiotherapy (XRT), and incubation in drug-free medium. Cell survival was assessed by colony formation assay and quantified by SRB kit at 14d post-XRT. Apoptosis was measured at 72 and 96h post-XRT, and expression of apoptotic proteins (i.e., cleaved PARP and cleaved CASPASE 3) was examined by immunoblotting. (iii) To determine radiosensitivity in vivo, we randomized 20 nude mice bearing QGP-1 xenografts into four groups: control; 3-AP (10mg/Kg); XRT (2 Gy); and combination (XRT immediately followed by 3-AP); each mouse received 5 consecutive treatments. Results: (i) A dose of 2500nM 3-AP arrested cells before entering G2/M phase, significantly reducing percentage of G2/M cells from 8.4% to 0.5% at 72h. Concurrently, we observed increased expression of checkpoint proteins (pRb, pCdk1, pCdk2, pCdc2) and decreased expression of cell cycle inhibitory proteins (cyclin D1, p21, p27 Kip). (ii) Exposure of QGP-1 and BON cells to 3-AP prior to XRT resulted in a synergistic decrease (i.e., 85% and 90%, respectively) in clonogenicity. Furthermore, the combination of 3-AP and XRT increased apoptosis 5-fold and cleaved PARP expression in BON cells. (iii) A significant decrease in tumor size was noted in mice with XRT alone compared to control (146mm2 vs. 280 mm2, respectively); combination treatment (3-AP + XRT) demonstrated a further 48% decrease in tumor size compared to XRT alone. There was no significant decrease in tumor size with 3-AP treatment alone. Conclusion: 3-AP treatment prior to XRT therapy resulted in significant increase in apoptosis in vitro and decrease in tumor size in vivo, suggesting synergistic cytotoxicity and radiosensitivity. Selective RNR inhibition by 3-AP provides a potent therapeutic strategy as a radiosensitizer and offers a novel approach in treating advanced GEP-NETs. Citation Format: Zeta Chow, Jeremy Johnson, Aman Chauhan, Tadahide Isumi, Lowell Anthony, Courtney M. Townsend, B. Mark Evers, Piotr Rychahou. 3-Aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP): A promising radiochemotherapy for gastroenteropancreatic neuroendocrine tumors [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-014.

Hsp90-mediated regulation of DYRK3 couples stress granule disassembly and growth via mTORC1 signaling.

Stress granules (SGs) are dynamic condensates associated with protein misfolding diseases. They sequester stalled mRNAs and signaling factors, such as the mTORC1 subunit raptor, suggesting that SGs coordinate cell growth during and after stress. However, the molecular mechanisms linking SG dynamics and signaling remain undefined. We report that the chaperone Hsp90 is required for SG dissolution. Hsp90 binds and stabilizes the dual‐specificity tyrosine‐phosphorylation‐regulated kinase 3 (DYRK3) in the cytosol. Upon Hsp90 inhibition, DYRK3 dissociates from Hsp90 and becomes inactive. Inactive DYRK3 is subjected to two different fates: it either partitions into SGs, where it is protected from irreversible aggregation, or it is degraded. In the presence of Hsp90, DYRK3 is active and promotes SG disassembly, restoring mTORC1 signaling and translation. Thus, Hsp90 links stress adaptation and cell growth by regulating the activity of a key kinase involved in condensate disassembly and translation restoration.

Three-dimensional low shear culture of Mycobacterium bovis BCG induces biofilm formation and antimicrobial drug tolerance

Mycobacteria naturally grow as corded biofilms in liquid media without detergent. Such detergent-free biofilm phenotypes may reflect the growth pattern of bacilli in tuberculous lung lesions. New strategies are required to treat tuberculosis, which is responsible for more deaths each year than any other bacterial disease. The lengthy 6-month regimen for drug-sensitive tuberculosis is necessary to remove antimicrobial drug tolerant populations of bacilli that persist through drug therapy. The role of biofilm-like growth in the generation of these sub-populations remains poorly understood despite the hypothesised clinical significance and mounting evidence of biofilms in pathogenesis. We adapt a three-dimensional Rotary Cell Culture System to model M. bovis BCG biofilm growth in low-shear detergent-free liquid suspension. Importantly, biofilms form without attachment to artificial surfaces and without severe nutrient starvation or environmental stress. Biofilm-derived planktonic bacilli are tolerant to isoniazid and streptomycin, but not rifampicin. This phenotypic drug tolerance is lost after passage in drug-free media. Transcriptional profiling reveals induction of cell surface regulators, sigE and BCG_0559c alongside the ESX-5 secretion apparatus in these low-shear liquid-suspension biofilms. This study engineers and characterises mycobacteria grown as a suspended biofilm, illuminating new drug discovery pathways for this deadly disease.

Genetic contribution to high temperature tolerance in Cryptococcus neoformans.

The human fungal pathogen Cryptococcus neoformans relies on a complex signaling network for the adaptation and survival at the host temperature. Protein phosphatase calcineurin is central to proliferation at 37°C but its exact contributions remain ill-defined. To better define genetic contributions to the C. neoformans temperature tolerance, 4031 gene knockouts were screened for genes essential at 37°C and under conditions that keep calcineurin inactive. Identified 83 candidate strains, potentially sensitive to 37°C, were subsequently subject to technologically simple yet robust assay, in which cells are exposed to a temperature gradient. This has resulted in identification of 46 genes contributing to the maximum temperature at which C. neoformans can proliferate (Tmax). The 46 mutants, characterized by a range of Tmax on drug-free media, were further assessed for Tmax under conditions that inhibit calcineurin, which led to identification of several previously uncharacterized knockouts exhibiting synthetic interaction with the inhibition of calcineurin. A mutant that lacked septin Cdc11 was among those with the lowest Tmax and failed to proliferate in the absence of calcineurin activity. To further define connections with calcineurin and the role for septins in high temperature growth, the 46 mutants were tested for cell morphology at 37°C and growth in the presence of agents disrupting cell wall and cell membrane. Mutants sensitive to calcineurin inhibition were tested for synthetic lethal interaction with deletion of the septin-encoding CDC12 and the localization of the septin Cdc3-mCherry. The analysis described here pointed to previously uncharacterized genes that were missed in standard growth assays indicating that the temperature gradient assay is a valuable complementary tool for elucidating the genetic basis of temperature range at which microorganisms proliferate.