K7M2 Cells Research Articles

Photothermally reinforced chemodynamic therapy in the treatment of osteosarcoma by polydopamine-modified, copper peroxide loaded ZIF8 nanoparticles

Chemodynamic therapy (CDT) has played an important role in osteosarcoma (OS) treatment. However, the insufficient content of endogenous H2O2 and high expression of glutathione (GSH) in tumor tissues limit the antitumor efficacy of CDT. In this work, we developed polydopamine (PDA) coated and CuO2 NPs loaded ZIF8 nanoparticles (CuO2@ZIF8@PDA NPs) for thermally reinforced CDT treatment of OS. The CuO2@ZIF8@PDA NPs exhibited excellent stability in neutral solutions while degraded in weakly acidic environments to generate hydrogen peroxide (H2O2) and Cu2+. Cu2+ consumes GSH in tumor tissues to generate Cu+. Both Cu2+ and Cu+ catalyzed the decomposition of H2O2, triggering a Fenton-like reaction to produce hydroxyl radicals (•OH). The PDA coating endowed the nanosystem with photothermal conversion capabilities under near-infrared laser irradiation, further promoting the generation of •OH, and inducing tumor cell death. In vitro experiments demonstrated that CuO2@ZIF8@PDA NPs exhibited significant toxicity towards K7M2 cells while remaining non-toxic to normal cells. In vivo studies revealed that under 808 nm laser irradiation, CuO2@ZIF8@PDA NPs exhibited stronger killing ability against K7M2 cells than CuO2@ZIF8@PDA NPs alone. This system, which combines GSH depletion, intratumoral H2O2 self-generation, and photothermally enhanced CDT, holds great promise for playing a pivotal role in the treatment of osteosarcoma.

Transient Receptor Potential Ankyrin 1 Ion Channel Is Expressed in Osteosarcoma and Its Activation Reduces Viability.

Osteosarcoma is a highly malignant, painful cancer with poor treatment opportunities and a bad prognosis. Transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors are non-selective cation channels that have been of great interest in cancer, as their expression is increased in some malignancies. In our study we aim to characterize the expression and functionality of the TRPA1 and TRPV1 channels in human and mouse osteosarcoma tissues and in a mouse cell line. TRPA1/Trpa1 and TRPV1/Trpv1 mRNA expressions were demonstrated by PCR gel electrophoresis and RNAscope in situ hybridization. The function of these channels was confirmed by their radioactive 45Ca2+ uptake in response to the TRPA1 agonist, Allyl-isothiocyanate (AITC), and TRPV1 agonist, capsaicin, in K7M2 cells. An ATP-based K2M7 cell viability luminescence assay was used to determine cell viability after AITC or capsaicin treatments. Both TRPA1/Trpa1 and TRPV1/Trpv1 were expressed similarly in human and mouse osteosarcoma tissues, while Trpa1 transcripts were more abundantly present in K7M2 cells. TRPA1 activation with 200 µM AITC induced a significant 45Ca2+ influx into K7M2 cells, and the antagonist attenuated this effect. In accordance with the lower Trpv1 expression, capsaicin induced a moderate 45Ca2+ uptake, which did not reach the level of statistical significance. Both AITC and capsaicin significantly reduced K7M2 cell viability, demonstrating EC50 values of 22 µM and 74 µM. The viability-decreasing effect of AITC was significantly but only partially antagonized by HC-030031, but the action of capsaicin was not affected by the TRPV1 antagonist capsazepine. We provide here the first data on the functional expression of the TRPA1 and TRPV1 ion channels in osteosarcoma, suggesting novel diagnostic and/or therapeutic perspectives.

Abstract 7554: The histone deacetylase inhibitor romidepsin is a potential therapeutic for metastatic osteosarcoma

Abstract Osteosarcoma predominately affects adolescents, young adults, and canines. For human patients, the five-year survival rate of those with detectable lung metastases is only 30% while most canine patients with metastatic disease die within 1-2 years. Standard therapy is not effective for this patient group, so it is therefore necessary to identify novel therapies that target the progression of lung metastases. Our lab previously screened 114 FDA-approved anti-cancer drugs to identify agents that decrease the growth of 3D spheroids (sarcospheres) generated from highly metastatic osteosarcoma cell lines. The top hits included both histone deacetylase inhibitors (HDIs) that were tested. In follow-up experiments measuring potency on sarcospheres and toxicity on non-transformed cells, romidepsin was the top hit of the 114-drug panel as well of the two additional FDA-approved HDIs and seven HDIs that are in clinical oncology trials. Our goal was therefore to further evaluate romidepsin as a potential therapy for metastatic osteosarcoma. Romidepsin potently decreased viability in sarcospheres from established highly metastatic osteosarcoma cell lines (relative ED50s = 3-36nM). About 50% of the patients (both canine and human) had similar responses to romidepsin (relative ED50s = 1- 18nM) suggesting that those patients might be good candidates for romidepsin therapy. This includes patients who had been heavily pretreated with standard-of-care osteosarcoma chemotherapeutics. Mechanistically, romidepsin blocks proliferation and causes a G2/M cell cycle arrest in fast growing sarcospheres (143B and MG63.3) while in slow growing sarcospheres (LM7 and K7M2) where primarily induces cytotoxicity and there is no cell cycle arrest. Patient-derived sarcospheres are slow growing, so we predict that the primary mechanism will be cytotoxicity. Using a tail vein injection model of osteosarcoma lung metastases, romidepsin dose dependently prolonged survival and reduced the area and number of lung metastases in immunodeficient mice injected with 143B cells and a syngeneic model using K7M2 cells. Romidepsin will be evaluated in mice with metastases from patient-derived cells and if effective, will be repurposed for canine and human clinical trials to improve outcomes in metastatic osteosarcoma without the associated costs and extensive timeframe of traditional drug discovery. Citation Format: Emily E. Seiden, Spencer M. Richardson, Shrey Ramnath, Tia Whiteside, Kathryn L. Coy, Anthony L. Sinn, Maegan L. Capitano, Karen E. Pollok, Chris D. Collier, Ed M. Greenfield. The histone deacetylase inhibitor romidepsin is a potential therapeutic for metastatic osteosarcoma [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 7554.

Abstract 5461: Antecedent STING agonist therapy improves tumor response to chemotherapy in murine models of osteosarcoma

Abstract Little improvement has been made in outcomes for pediatric patients with osteosarcoma in decades. Cytotoxic chemotherapy alone is insufficient for cure and upfront complete surgical resection is usually required to achieve long-term survival. Better systemic therapies are needed. Osteosarcoma is characterized by a high degree of genomic instability that would suggest these tumors have sufficient neoantigen burden to be immunogenic and responsive to immunotherapy, but trials of immune checkpoint inhibitors in osteosarcoma have shown poor effectiveness. Although immunotherapy drugs targeting the adaptive immune system have worked poorly, we hypothesize that an innate immune adjuvant - stimulator of interferon response cGAMP interactor 1 (STING) agonist - in combination with cytotoxic chemotherapy would improve chemotherapy effectiveness and immune-mediated tumor clearance, particularly given the abundance of innate immune cells in the microenvironment of these tumors. Using two different immune-competent in vivo murine models of osteosarcoma (K7M2 in BALB/c mice and F420 in C57BL/6 mice), we challenged mice with tumor cells via subcutaneous or intratibial injection. In all experimental replicates, we observed improved tumor regression in mice treated with intratumoral STING agonist followed by intraperitoneal treatment with carboplatin. Responses included complete tumor response in up to 40% of treated mice. Treatment with STING agonist alone or carboplatin alone only delayed tumor growth compared to untreated controls. Additionally, mice treated first with carboplatin and then with STING agonist demonstrated an initial modest response to treatment, but ultimately exhibited tumor progression, suggesting an importance to the sequence of STING agonist administration. In vitro treatment of K7M2 and F420 cells with STING agonist showed a tumor-intrinsic transient increase in expression of pro-inflammatory mediators Cxcl10, Ccl5, and Ifnb 4 hours after STING exposure. Flow cytometry analysis of K7M2 tumors demonstrated increased infiltration of STING/carboplatin-treated tumors with CD8+/IFNγ+ lymphocytes and CD11b+/MHCII+/F480+ tumor-associated macrophages. Interestingly, these tumors also demonstrated an increased quantity of CD11b+/MHCII-/F480-/Ly6Glo/Ly6C+ myeloid-derived suppressor cells despite their favorable clinical response. Our findings suggest that intratumoral STING agonist therapy stimulates tumor-intrinsic and tumor-extrinsic pro-inflammatory mediators that improve the tumor response to treatment with carboplatin. Ongoing studies are further investigating the tumor-intrinsic and extrinsic mediators that are driving this improved response to therapy. Citation Format: Erin E. Resch, Emily Kulp, Michele Doucet, Alice Recho, Brian H. Ladle. Antecedent STING agonist therapy improves tumor response to chemotherapy in murine models of osteosarcoma [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 5461.

Zeolitic Imidazolate Framework (ZIF-8) Decorated Iron Oxide Nanoparticles Loaded Doxorubicin Hydrochloride for Osteosarcoma Treatment - in vitro and in vivo Preclinical Studies.

As a broad-spectrum antitumorigenic agent, doxorubicin (DOX) is commonly used as a chemotherapeutic drug for treating osteosarcoma (OS). Still, it is associated with significant cell toxicity and ineffective drug delivery, whereas the zeolite imidazolate framework is extensively applied in the biomedical field as a carrier owing to its favorable biocompatibility, high porosity, and pH-responsiveness. Therefore, we need to develop a drug delivery platform that can effectively increase the antitumorigenic effect of the loaded drug and concurrently minimize drug toxicity. In this study, a Fe3O4@ZIF-8 nanocomposite carrier was prepared with ZIF-8 as the shell and encapsulated with Fe3O4 by loading DOX to form DOX- Fe3O4@ZIF-8 (DFZ) drug-loaded magnetic nanoparticles. Then, we characterized and analyzed the morphology, particle size, and characteristics of Fe3O4@ZIF-8 and DFZ by TEM, SEM, and Malvern. Moreover, we examined the inhibitory effects of DFZ in vitro and in vivo. Meanwhile, we established a tumor-bearing mouse model, evaluating its tumor-targeting by external magnetic field guidance. DFZ nanoparticles possessed have a size of ~110 nm, with an encapsulation rate of 21% and pH responsiveness. DFZ exerted a superior cytostatic effect and apoptosis rate on K7M2 cells in vitro compared to DOX(p<0.01). In animal experiments, DFZ offers up to 67% tumor inhibition and has shown a superior ability to induce apoptosis than DOX alone in TUNEL results(p<0.01). Tumor-targeting experiments have validated that DFZ can be effectively accumulated in the tumor tissue and enhance anticancer performance. In summary, the DFZ nano-delivery system exhibited a more substantial anti-tumorigenic effect as well as superior active tumor targeting of DOX- Fe3O4@ZIF-8 compared to that of DOX alone in terms of biocompatibility, drug loading capacity, pH-responsiveness, tumor-targeting, and anti-tumorigenic effect, indicating its chemotherapeutic application potential.

Phenethyl isothiocyanate induces oxidative cell death in osteosarcoma cells with regulation on mitochondrial network, function and metabolism

Phenethyl isothiocyanate (PEITC), a kind of isothiocyanate available in cruciferous vegetables, exhibits inhibitory effects on cancers. PEITC has been extensively recorded for its effect on regulation of redox status in cancer cells. Our previous studies revealed that PEITC induced ROS-dependent cell death in osteosarcoma. Mitochondria are the main sites for ROS generation and play significant role in deciding cell fate. To dissect the mechanism of PEITC's action on osteosarcoma cells, we detected the changes on mitochondrial network, function and metabolism in K7M2 and 143B cells. Here, PEITC induced cytosolic, lipid and mitochondrial ROS production in osteosarcoma cells. It changed mitochondrial morphology from elongated to punctate network and decreased mitochondrial mass. Meantime, PEITC increased mitochondrial transmembrane potential in short time, decreased it with time prolonged, and later collapsed it in K7M2 cells, and reduced it in 143B cells. PEITC inhibited proliferation potential of osteosarcoma cells with damage on mitochondrial respiratory chain complexes. Further, PEITC-treated osteosarcoma cells experienced a sudden increase in ATP level, and later its content was decreased. Moreover, PEITC downregulated the expressions of mitochondrial respiratory chain complexes including COX IV, UQCR, SDHA and NDUFA9 in 143B cells and COX IV in K7M2 cells. At last, by using ρ0 cells derived from K7M2 and 143B cells, we found that osteosarcoma cells that depleted mtDNA were less sensitive to PEITC-induced changes on cellular morphology, cytoskeleton filament, mitochondrial transmembrane potential and ROS generation. In conclusion, our study demonstrated that mitochondria may play important role in PEITC-induced oxidative cell death in osteosarcoma cells.

Targeted Deletion of Rictor in BMSCs Reduces the Biological Activity of K7M2 Cells and Mitigates OS-Induced Bone Destruction.

Bone marrow mesenchymal stem cells (BMSCs) are indispensable cells constituting the bone marrow microenvironment that are generally recognized as being involved in the development and progression of osteosarcoma (OS). To explore whether mTORC2 signaling inhibition in BMSCs suppressed OS growth and tumor-caused bone destruction, 3-month-old littermates genotyped Rictorflox/flox or Prx1-cre; Rictorflox/flox (with same gender) were injected with K7M2 cells in the proximal tibia. After 40 days, bone destruction was alleviated in Prx1-cre; Rictorflox/flox mice, as observed on X-ray and micro-CT. This was accompanied by decreased serum N-terminal propeptide of procollagen type I (PINP) levels and reduced tumor bone formation in vivo. Interactions between K7M2 and BMSCs were studied in vitro. Rictor-deficient BMSCs, which were cultured in tumor-conditioned medium (TCM), caused reduced bone proliferation and suppressed osteogenic differentiation. Moreover, compared with the control group, K7M2 cells cultured in BCM (culture medium extracted from Rictor-deficient BMSCs) displayed less proliferation, migration, and invasion, and attenuated osteogenic activity. Forty types of cytokines were then analyzed by mouse cytokine array and decreased levels CCL2/3/5 and interleukin-16 were detected in Rictor-deficient BMSCs. These results suggested that inhibition of mTORC2 (Rictor) signaling pathway in BMSCs exerted anti-OS effects through 2 mechanisms: (1) by suppressing the proliferation and osteogenic differentiation of BMSCs induced by OS to alleviate bone destruction; (2) by reducing the secretion of cytokines by BMSCs, which are closely related to OS cell growth, migration, invasion, and tumorigenic osteogenesis.

Extracellular Vesicles Derived From 3D Cultured Antler Stem Cells Serve as a New Drug Vehicle in Osteosarcoma Treatment

Extracellular vesicles (EVs) from antler reserve mesenchymal (RM) cells play an important role in the paracrine regulation during rapid growth of antler without forming a tumor; therefore, RM-EVs become novel materials for anti-tumor studies, such as osteosarcoma treatment. However, the problem of low production of RM-EVs in traditional 2D culture limits its mechanism research and application. In this study, we established an optimal 3D culture system for antler RM cells to produce EVs (3D-RM-EVs). Morphology and property of harvested 3D-RM-EVs were normal compared with EVs from conventional 2D culture, and the miRNA profile in them was basically the same through transcriptome sequencing analysis. Based on the same number of RM cells, the volume of the culture medium collected by 3D cultural system concentrated nearly 30 times, making it more convenient for subsequent purification. In addition, EVs were harvested 30 times in 3D cultural system, greatly increasing the total amount of EVs (harvested a total of 2–3 times in 2D culture). Although 3D-RM-EVs had a limited inhibitory effect on the proliferation of K7M2 cells, the inhibition effect of 3D-RM-EVs loaded drugs (Ifosfamide + Etoposide) were more significant than that of positive drug group alone (P < 0.05). Furthermore, in vivo studies showed that 3D-RM-EVs loaded drugs (Ifosfamide + Etoposide) had the most significant tumor inhibition effect, with decreased tumor size, and could slow down body weight loss compared with Ifosfamide + Etoposide (IFO + ET) group. These results demonstrated that 3D-RM-EVs were efficiently prepared from antler RM cells and were effective as drug vehicles for the treatment of osteosarcoma.

Iron plays a role in sulfasalazine-induced ferroptosis with autophagic flux blockage in K7M2 osteosarcoma cells.

Osteosarcoma is the most common primary bone malignancy in children and young adults, with a very poor prognosis. It is of great importance to develop targeted therapeutic strategies for osteosarcoma. Sulfasalazine (SAS) is an FDA-approved drug for the treatment of Crohn's disease, rheumatoid arthritis, and inflammatory bowel disease. It acts as an inhibitor of cystine/glutamate system, which is important for cellular glutathione synthesis and maintenance of GPx4 activity. Nowadays, SAS has been repurposed as an antitumor drug for inducing ferroptosis in cancers. This study aimed to uncover the role of iron in SAS-induced ferroptotic cell death in K7M2 osteosarcoma cells. Herein, SAS led to an iron-dependent cell death mode in K7M2 cells, accompanied with decreased antioxidant defense and increased production of cytosolic and lipid reactive oxygen species. Results also showed that iron supplement with ferric ammonium citrate (FAC) or ferrous ammonium sulfate (FAS) exacerbated the declined cell viability of SAS-treated K7M2 cells, while in the case of iron depletion, it weakened such suppression. Furthermore, iron promoted SAS-induced alterations on cell cycle, cytoskeleton, mitochondria morphology and function, and redox system. Iron also induced the dysfunction of autophagic activity in SAS-treated K7M2 cells. In conclusion, our study uncovered the essential role of iron in SAS's effects on K7M2 cells and provided the potential combined therapy of inhibition on antioxidant defense and an increase in oxidative potential, which further disturbed the redox status in tumor cells.

Honeycomb-Like Hydrogel Microspheres for 3D Bulk Construction of Tumor Models.

A two-dimensional (2D) cell culture-based model is widely applied to study tumorigenic mechanisms and drug screening. However, it cannot authentically simulate the three-dimensional (3D) microenvironment of solid tumors and provide reliable and predictable data in response to in vivo, thus leading to the research illusions and failure of drug screening. In this study, honeycomb-like gelatin methacryloyl (GelMA) hydrogel microspheres are developed by synchronous photocrosslinking microfluidic technique to construct a 3D model of osteosarcoma. The in vitro study shows that osteosarcoma cells (K7M2) cultured in 3D GelMA microspheres have stronger tumorous stemness, proliferation and migration abilities, more osteoclastogenetic ability, and resistance to chemotherapeutic drugs (DOX) than that of cells in 2D cultures. More importantly, the 3D-cultured K7M2 cells show more tumorigenicity in immunologically sound mice, characterized by shorter tumorigenesis time, larger tumor volume, severe bone destruction, and higher mortality. In conclusion, honeycomb-like porous microsphere scaffolds are constructed with uniform structure by microfluidic technology to massively produce tumor cells with original phenotypes. Those microspheres could recapitulate the physiology microenvironment of tumors, maintain cell-cell and cell-extracellular matrix interactions, and thus provide an effective and convenient strategy for tumor pathogenesis and drug screening research.

Determination of VEGF165 using impedimetric aptasensor based on cyclohexanehexone-melem covalent-organic framework.

Aporous nanostructured covalent-organic framework (COF) has been preparedvia condensation polymerization between the two building blocks of melem and hexaketocyclohexane octahydrate (represented as M-HO-COF). Basic characterizations revealed that the M-HO-COF network was composed of C=N and highly conjugated aromatic moieties, along with a high surface area, large pore size, remarkable electrochemical activity, and strong bioaffinity toward aptamer strands. Given that thevascular endothelial growth factor 165 (VEGF165)-targeted aptamer was stably anchored over M-HO-COF via weak intermolecular forces, the prepared M-HO-COF network exhibited great potential as a sensitive and selective platform for the impedimetric VEGF165 aptasensor. Consequently, the M-HO-COF-based aptasensor displayed an ultralow limit of detection of 0.18fgmL-1 within a wide range of VEGF165 concentrations from 1fgmL-1 to 10ngmL-1. Considering its strong fluorescence performance, excellent biocompatibility, and small nanosheet-like structure, the obtained COF-based aptasensor showed a superior sensing performance and regeneration capability after 7 regeneration cycles for the detection of osteosarcoma cells (K7M2 cells), which overexpressed with VEGF165, with a low limit of detection of 49 cells mL-1. For real f human serumsamples, the obtained COF-based aptasensor exhibits acceptable mean apparent recoveries of 97.41% with arelative standard deviation of 4.60%. Furthermore, the proposed bifunctional aptasensor for the detection VEGF165 and K7M2 cells exhibited good stability, appropriate selectivity toward other biomarkers or normal cells, acceptable reproducibility, and applicability. A bifunctional sensing system was constructed for detecting osteosarcoma cells (K7M2 cells) and VEGF165 based on the a porous nanostructured covalent-organic framework (M-HO-COF) via condensation polymerization between melem and hexaketocyclohexane octahydrate. The M-HO-COF-based aptasensor displayed ultralow detection limit of 0.18fgmL-1 toward VEGF165 and 49 cell mL-1 for K7M2 cells with high selectivity, acceptable reproducibility, and good stability.

Parathyroid hormone type 1 receptor regulates osteosarcoma K7M2 Cell growth by interacting with angiotensinogen.

This study aimed to determine the interactions between parathyroid hormone type 1 receptor (PTHR1) and angiotensinogen (AGT) and the effects of these agents on osteosarcoma (OS). We constructed a stably transfected mouse OS K7M2 cell line (shPTHR1‐ K7M2) using shRNA and knocked down AGT in these cells using siRNA‐AGT. The transfection efficiency and expression of AGT, chemokine C‐C motif receptor 3 (CCR3), and chemokine (C‐C motif) ligand 9 (CCL9) were determined using real‐time quantitative PCR. Cell viability and colony formation were assessed using Cell Counting Kit‐8 and crystal violet staining, respectively. Cell apoptosis and cycle phases were assessed by flow cytometry, and cell migration and invasion were evaluated using Transwell assays. Interference with PTHR1 upregulated the expression of AGT and CCR3, and downregulated that of CCL9, which was further downregulated by AGT knockdown. Cell viability, migration, invasion and colony formation were significantly decreased, while cell apoptosis was significantly increased in shPTHR1‐K7M2, compared with those in K7M2 cells (P < .05 for all). However, AGT knockdown further inhibited cell viability after 72 h of culture but promoted cell migration and invasion. PTHR1 interference decreased and increased the numbers of cells in the G0/G1 and G2/M phases, respectively, compared with those in K7M2 cells. Angiotensinogen knockdown increased the number of cells in the G0/G1 phase compared with that in the shPTHR1‐K7M2 cells. Therefore, PTHR1 affects cell viability, apoptosis, migration, invasion and colony formation, possibly by regulating AGT/CCL9 in OS cells.

Telomerase-specific oncolytic immunotherapy for promoting efficacy of PD-1 blockade in osteosarcoma.

Immune checkpoint inhibitors including anti-programmed cell death 1 (PD-1) antibody have recently improved clinical outcome in certain cancer patients; however, osteosarcoma (OS) patients are refractory to PD-1 blockade. Oncolytic virotherapy has emerged as novel immunogenic therapy to augment antitumor immune response. We developed a telomerase-specific replication-competent oncolytic adenovirus OBP-502 that induces lytic cell death via binding to integrins. In this study, we assessed the combined effect of PD-1 blockade and OBP-502 in OS cells. The expression of coxsackie and adenovirus receptor (CAR), integrins αvβ3 and αvβ5, and programmed cell death ligand 1 (PD-L1) was analyzed in two murine OS cells (K7M2, NHOS). The cytopathic activity of OBP-502 in both cells was analyzed using the XTT assay. OBP-502-induced immunogenic cell death was assessed by analyzing the level of extracellular ATP and high-mobility group box protein B1 (HMGB1). Subcutaneous tumor models for K7M2 and NHOS cells were used to evaluate the antitumor effect and number of tumor-infiltrating CD8+ cells in combination therapy. K7M2 and NHOS cells showed high expression of integrins αvβ3 and αvβ5, but not CAR. OBP-502 significantly suppressed the viability of both cells, in which PD-L1 expression and the release of ATP and HMGB1 were significantly increased. Intratumoral injection of OBP-502 significantly augmented the efficacy of PD-1 blockade on subcutaneous K2M2 and NHOS tumor models via enhancement of tumor-infiltrating CD8+ T cells. Our results suggest that telomerase-specific oncolytic virotherapy is a promising antitumor strategy to promote the efficacy of PD-1 blockade in OS.

CuFeS2 Nanoassemblies With Intense Near-Infrared Absorbance for Photothermal Therapy of Tumors

Photothermal therapy is an efficient cancer treatment method. The development of nanoagents with high biocompatibility and near-infrared (NIR) photoabsorption band is a prerequisite to the success of this method. However, the therapeutic efficiency of photothermal therapy is rather limited because most of the nanoagents have a low photothermal conversion efficiency. In this study, we aimed to develop CuFeS2 nanoassemblies with an excellent photothermal effect using the liquid-solid-solution method. The CuFeS2 nanoassemblies we developed are composed of ultrasmall CuFeS2 nanoparticles with an average size of 5 nm, which have strong NIR photoabsorption. Under NIR laser illumination at 808 nm at the output power intensity of 1.0 W cm-2, the CuFeS2 nanoassemblies could rapidly convert NIR light into heat, achieving a high photothermal conversion efficiency of 46.8%. When K7M2 cells were incubated with the CuFeS2 nanoassemblies and then exposed to irradiation, their viability decreased progressively as the concentration of the CuFeS2 nanoassemblies increased. Furthermore, a concentration of 40 ppm of CuFeS2 nanoassemblies was lethal to the cells. Importantly, after intratumoral injection of 40 ppm CuFeS2 nanoassemblies, the tumor showed a high contrast in the thermal image after laser irradiation, and tumor cells with condensed nuclei and a loss of cell morphology could be thermally ablated. Therefore, the CuFeS2 nanoassemblies we synthesized have a high biocompatibility and robust photothermal effect and can, thus, be utilized as a novel and efficient photothermal agent for tumor therapy.

Water extract of sporoderm-broken spores of Ganoderma lucidum enhanced pd-l1 antibody efficiency through downregulation and relieved complications of pd-l1 monoclonal antibody

PurposeOsteosarcoma is a malignant musculoskeletal tumor with early metastasis and a poor prognosis, especially in adolescents. Ganoderma lucidum (Leyss. Ex Fr.) Karst (G. lucidum), a traditional East Asian medicine, has been reported to play a critical role in antitumor and immunomodulatory activity. The aim of this study was to investigate the effects and molecular mechanisms of water extract of sporoderm-broken spores of G. lucidum (BSGWE) on osteosarcoma PD-L1 (programmed cell death-ligand 1) transcriptional regulation, efficacy enhancement, and side effect remission. MethodsThe antitumor effects on cell proliferation of BSGWE in osteosarcoma cells were detected by apoptosis flow cytometry, and the migration ability of HOS and K7M2 cells were evaluated by cell scratch assay. Potential signaling regulation of PD-L1 was detected by western blotting. To confirm the signaling pathway of BSGWE-related PD-L1 downregulation, a pho-STAT3 turnover experiment was carried out. Colivelin was administered as a pho-STAT3 activator to rescue the BSGWE-induced PD-L1 inhibition. To further study in vivo signaling, in a Balb/c osteosarcoma allograft model, tumor volume was measured using an in vivo bioluminescence imaging system. The body weight curve and tumor volume curve were analyzed to reveal the remission effects of BSGWE on PD-L1 antibody-related body weight loss and its immunomodulatory effects on the osteosarcoma and spleen. The PD-L1 expression level and expression of related transcription-factor pho-STAT3 in tumor cells and spleens were assessed by IHC analysis. ResultsBSGWE suppressed the proliferation and migration of osteosarcoma cells in vitro via induction of apoptosis. In addition, BSGWE downregulated PD-L1 expression and related STAT3 (signal transducers and activators of transcription) phosphorylation levels in a dose-dependent manner. Western blotting and qRT-PCR assay revealed that BSGWE downregulated PD-L1 expression by inhibiting STAT3 phosphorylation. A turnover experiment showed that colivelin administration could rescue PD-L1 inhibition via pho-STAT3 activation. BSGWE not only downregulated PD-L1 expression via the STAT3 pathway in an allograft Balb/c mouse model, but also relieved complications including weight loss and spleen atrophy in a mouse monoclonal antibody therapy model on the basis of its traditional advantages in immune enhancement. ConclusionBSGWE downregulated PD-L1 expression via pho-STAT3 inhibition of protein and RNA levels. BSGWE enhanced PD-L1 antibody efficacy via phosphorylated STAT3 downregulation in vitro and in vivo. BSGWE also relieved complications of weight loss and spleen atrophy in a murine allograft osteosarcoma immune checkpoint blockade therapy model.

Improved Drug Delivery System for Cancer Treatment by D-Glucose Conjugation with Eugenol From Natural Product.

Bioconjugations are swiftly progressing and are being applied to solve several limitations of conventional Drug Delivery Systems (DDS) such as lack of water solubility, non-specific, and poor bioavailability. The main goals of DDS are to achieve greater drug effectiveness and minimize toxicity to the healthy tissues. In this study, D-glucose was conjugated with eugenol to target the cancer cells. To identify the implication of the anticancer effect, osteosarcoma (K7M2) cells were cultured and the anti-proliferative effect was performed using MTT [3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide assay] test in order to evaluate the viability and toxicity on cells with various concentrations of eugenol and D-glucose-eugenol conjugate in 24-hour incubation. It was found that, the successful confirmation of the conjugation between D-glucose and eugenol was obtained by 1H NMR spectroscopy. MTT assay showed inhibitory concentration (IC50 value) of D-glucose-eugenol was at 96.2 μg/ml and the decreased of osteosarcoma cell survival was 48%. Conclucion: These findings strongly indicate that K7M2 cells would be affected by toxicity of Dglucose- eugenol. Therefore, the present study suggests that D-glucose-eugenol has high potential to act as an anti-proliferative agent who may promise a new modality or approach as the drug delivery treatment for cancer or chemotherapeutic agent.

Abstract PR13: Surgical excision of the primary tumor in osteosarcoma model results in enhanced metastatic growth by modulating the lung immune microenvironment

Abstract Surgery has been shown to enhance metastasis in a number of cancers. To examine this in the context of osteosarcoma, we implanted syngeneic murine K7M2 cells into the tibia of BALB/c mice, which we had shown previously to result in immediate seeding of K7M2 cells into the lung. One week post-implantation, mice were assigned to either control or surgical groups and all mice were euthanized at week 4 post-implantation. Mice that underwent amputation of the primary tumor displayed an increase in the number of pulmonary surface nodules as compared to tumor-bearing control animals (17 vs. 9.5; p&amp;lt;0.05), showing that excision of the primary tumor indeed enhances metastasis in this model. As we previously showed that K7M2 metastasis without surgical intervention is strongly inhibited by re-educating tumor-associated macrophages (TAMs) with gefitinib, we also examined the effect of gefitinib on surgery-accelerated metastasis. We found that perioperative gefitinib abrogated the effects of primary tumor removal on the development of pulmonary metastases (17 vs. 6; p&amp;lt; 0.01), strongly suggesting that TAMs also mediate surgery-accelerated metastasis. To examine changes in the pulmonary immune milieu, we utilized the same model of surgery-accelerated metastasis. Lungs were homogenized and immune cell populations were analyzed using flow cytometric analysis at 48 hours and 3 weeks after surgery. We found that surgery caused a significant reduction in antitumor macrophages, identified by MHCII positivity (21.1% vs. 13.2%; p&amp;lt;0.01), and a significant increase in protumor macrophages, identified by CD206 positivity (33.0% vs. 42.4%; p&amp;lt;0.01), at 48 hours after surgical resection. There was no change in the proportion of CD4+ or CD8+ T cells at this time point. At 3 weeks post-surgery the proportion of macrophage populations became similar for both groups, but there was now a small but significant reduction in the CD4+ and CD8+ T cells in the surgical group (68.4% vs. 60.3%; p&amp;lt;0.05 and 25.0% vs. 19.3%; p&amp;lt;0.01). In conclusion, surgical removal of the primary tumor accelerated the growth of pulmonary metastases in a murine model of OS. Gefitinib was able to abrogate this effect, suggesting macrophages as key cellular mediators. Furthermore, surgery altered the macrophage phenotype within the lungs in the acute postoperative period toward a protumor state, subsequently reducing the CD4+ or CD8+ T-cell populations. Taken together these data suggest that surgery contributes to enhanced metastatic outgrowth by altering the immune microenvironment to an immunosuppressive and protumor state. This abstract is also being presented as Poster B38. Citation Format: Michelle P. Kallis, Caroline Maloney, Morris Edelman, Samuel Z. Soffer, Marc Symons, Bettie M. Steinberg. Surgical excision of the primary tumor in osteosarcoma model results in enhanced metastatic growth by modulating the lung immune microenvironment [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr PR13.

Empirical and theoretical insights into the structural effects of selenite doping in hydroxyapatite and the ensuing inhibition of osteoclasts.

The use of ions as therapeutic agents has the potential to minimize the use of small-molecule drugs and biologics for the same purpose, thus providing a potentially more economic and less adverse means of treating, ameliorating or preventing a number of diseases. Hydroxyapatite (HAp) is a solid compound capable of accommodating foreign ions with a broad range of sizes and charges and its properties can dramatically change with the incorporation of these ionic additives. While most ionic substitutes in HAp have been monatomic cations, their lesser atomic weight, higher diffusivity, chaotropy and a lesser residence time on surfaces theoretically makes them prone to exert a lesser influence on the material/cell interaction than the more kosmotropic oxyanions. Selenite ion as an anionic substitution in HAp was explored in this study for its ability to affect the short-range and the long-range crystalline symmetry and solubility as well as for its ability to affect the osteoclast activity. We combined microstructural, crystallographic and spectroscopic analyses with quantum mechanical calculations to understand the structural effects of doping HAp with selenite. Integration of selenite ions into the crystal structure of HAp elongated the crystals along the c-axis, but isotropically lowered the crystallinity. It also increased the roughness of the material in direct proportion with the content of the selenite dopant, thus having a potentially positive effect on cell adhesion and integration with the host tissue. Selenite in total acted as a crystal structure breaker, but was also able to bring about symmetry at the local and global scales within specific concentration windows, indicating a variety of often mutually antagonistic crystallographic effects that it can induce in a concentration-dependent manner. Experimental determination of the lattice strain coupled with ab initio calculations on three different forms of carbonated HAp (A-type, B-type, AB-type) demonstrated that selenite ions initially substitute carbonates in the crystal structure of carbonated HAp, before substituting phosphates at higher concentrations. The most energetically favored selenite-doped HAp is of AB-type, followed by the B-type and only then by the A-type. This order of stability was entailed by the variation in the geometry and orientation of both the selenite ion and its neighboring phosphates and/or carbonates. The incorporation of selenite in different types of carbonated HAp also caused variations of different thermodynamic parameters, including entropy, enthalpy, heat capacity, and the Gibbs free energy. Solubility of HAp accommodating 1.2wt% of selenite was 2.5 times higher than that of undoped HAp and the ensuing release of the selenite ion was directly responsible for inhibiting RAW264.7 osteoclasts. Dose-response curves demonstrated that the inhibition of osteoclasts was directly proportional to the concentration of selenite-doped HAp and to the selenite content in it. Meanwhile, selenite-doped HAp had a significantly less adverse effect on osteoblastic K7M2 and MC3T3-E1 cells than on RAW264.7 osteoclasts. The therapeutically promising osteoblast vs. osteoclast selectivity of inhibition was absent when the cells were challenged with undoped HAp, indicating that it is caused by selenite ions in HAp rather than by HAp alone. It is concluded that like three oxygens building the selenite pyramid, the coupling of (1) experimental materials science, (2) quantum mechanical modeling and (3) biological assaying is a triad from which a deeper understanding of ion-doped HAp and other biomaterials can emanate.

PEITC triggers multiple forms of cell death by GSH-iron-ROS regulation in K7M2 murine osteosarcoma cells.

Phenethyl isothiocyanate (PEITC) is an isothiocyanate that largely exists in cruciferous vegetables and exhibits chemopreventive and chemotherapeutic potential against various cancers. However, it is little known about the molecular mechanisms of its antitumor action against osteosarcoma, which is the second highest cause of cancer-related death in children and adolescents. In this study, we investigated the effects of PEITC on K7M2 murine osteosarcoma both in vitro and in vivo. We found that treatment with PEITC dose-dependently inhibited the viability of K7M2 murine osteosarcoma cells with an IC50 value of 33.49 μM at 24 h. PEITC (1, 15, 30 μM) dose-dependently inhibited the cell proliferation, caused G2/M cell cycle arrest, depleted glutathione (GSH), generated reactive oxygen species (ROS), altered iron metabolism, and triggered multiple forms of cell death, namely ferroptosis, apoptosis, and autophagy in K7M2 cells. We further revealed that PEITC treatment activated MAPK signaling pathway, and ROS generation was a major cause of PEITC-induced cell death. In a syngeneic orthotopic osteosarcoma mouse model, administration of PEITC (30, 60 mg/kg every day, ig, for 24 days) significantly inhibited the tumor growth, but higher dose of PEITC (90 mg/kg every day) compromised its anti-osteosarcoma effect. Histological examination showed that multiple cell death processes were initiated, iron metabolism was altered and MAPK signaling pathway was activated in the tumor tissues. In conclusion, we demonstrate that PEITC induces ferroptosis, autophagy, and apoptosis in K7M2 osteosarcoma cells by activating the ROS-related MAPK signaling pathway. PEITC has promising anti-osteosarcoma activity. This study sheds light on the redox signaling-based chemotherapeutics for cancers.

Blocking the PD-1/PD-L1 axis enhanced cisplatin chemotherapy in osteosarcoma in vitro and in vivo

BackgroundThe blocking of the programmed cell death protein (PD-1)/programmed death-ligand 1 (PD-L1) axis has been found to have an anticancer activity against various types of cancer by enhancing T cell immunity, while there are no studies linking the PD-1/PD-L1 axis to chemotherapy drugs in osteosarcoma (OS). The present study aimed to investigate the effects of blocking PD-1/PD-L1 axis on the cisplatin chemotherapy in OS in vitro and in vivo.MethodsReverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to detect PD-L1 mRNA in OS tissues. Cell proliferation and apoptosis were measured by Cell Counting Kit-8 (CCK-8) and flow cytometry assays, respectively. In vivo, the syngeneic mice were treated with cisplatin and anti-PD-1 antibody alone or jointly.ResultsIn this study, it revealed that PD-L1 mRNA was highly expressed in OS tissues. Further inhibitory evaluation showed that the K7M2-LV cells (PD-L1 overexpression) co-cultured with PD-1+ lymphocytes could promote K7M2 cell proliferation. Meanwhile, the combination of anti-PD-1 antibody and cisplatin significantly decreased the proliferation and increased the apoptosis of K7M2 cells in a co-culture system. In vivo, the combination of anti-PD-1 antibody and cisplatin significantly inhibited tumor growth, while the mechanisms did not involve regulatory T cells.ConclusionThe present data suggested that the blocking of PD-1/PD-L1 axis had a positive prognostic value, which can enhance the chemotherapeutic effect of cisplatin in OS. These findings provide a rationale for utilizing PD1/PD-L1 blocking antibodies as a single agent to cure refractory OS in patients receiving cisplatin treatment.