AMD3100 combined with triptolide inhibit proliferation, invasion and metastasis and induce apoptosis of human U2OS osteosarcoma cells

Pharmacological, computational, and mechanistic insights into triptolide's role in targeting drug-resistant cancers

As a promising candidate for tackling drug-resistant cancers, triptolide, a diterpenoid derived from the Chinese medicinal plant Tripterygium wilfordii, has been developed. This review summarizes potential antitumor activities, including the suppression of RNA polymerase II, the suppression of heat shock proteins (HSP70 and HSP90), and the blockade of NF-kB signalling. Triptolide is the first known compound to target cancer cells specifically but spare normal cells, and it has success in treating cancers that are difficult to treat, including pancreatic, breast, and lung cancers. It acts against the tolerance mechanisms, including efflux pump upregulation, epithelial-mesenchymal transition, and cancer stem cells. Triptolide modulates important cascades, including PI3K/AKT/mTOR, enhancing the efficacy of conventional therapies. Nonetheless, its clinical application is constrained by toxicity and bioavailability challenges. Emerging drug delivery systems, such as nanoparticles and micellar formulations, are being developed to address these limitations. It has strong interactions with key anticancer targets, like PARP, as determined in preclinical and computational studies consistent with its mechanism of action. Early-phase clinical trials of Minnelide, a water-soluble derivative of triptolide, are promising, but additional work is necessary to optimize dosing, delivery, and safety. This comprehensive analysis demonstrates that triptolide may constitute a repurposed precision medicine tool to overcome tolerance in cancer therapy.

The sEVs miR-487a/Notch2/GATA3 axis promotes osteosarcoma lung metastasis by inducing macrophage polarization toward the M2-subtype

Small extracellular vesicles (sEVs) are important mediators of intercellular communication between tumor cells and their surrounding environment. Furthermore, the mechanisms by which miRNAs carried in tumor sEVs regulate macrophage polarization remain largely unknown. To concentrate sEVs, we used the traditional ultracentrifugation method. Western blot, NanoSight, and transmission electron microscopy were used to identify sEVs. To determine the function of sEVs-miR-487a, we conducted in vivo and in vitro investigations. The intercellular communication mechanism between osteosarcoma cells and M2 macrophages, mediated by sEVs carrying miR-487a, was validated using luciferase reporter assays, transwell assays, and Western blot analysis. In vitro, sEVs enriched in miR-487a and delivered miR-487a to macrophages, promoting macrophage polarization toward an M2-like type, which promotes proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. In vivo, sEVs enriched in miR-487a facilitate lung metastasis of osteosarcoma. Moreover, plasma miR-487a in sEVs was shown to be a potential biomarker applicable for osteosarcoma diagnosis. In summary, miR-487a derived from osteosarcoma cells can be transferred to macrophages via sEVs, then promote macrophage polarization towards an M2-like type by targeting Notch2 and activating the GATA3 pathway. In a feedback loop, the activation of macrophages accelerates epithelial-mesenchymal transition (EMT), which in turn promotes the migration, invasion, and lung metastasis of osteosarcoma cells. This reciprocal interaction between activated macrophages and osteosarcoma cells contributes to the progression of the disease. Our data demonstrate a new mechanism that osteosarcoma tumor cells derived exosomal-miR-487a which is involved in osteosarcoma development by regulating macrophage polarization in tumor microenvironment (TME).

Crosstalk between CXCL12/CXCR4/ACKR3 and the STAT3 Pathway

The reciprocal modulation between the CXCL12/CXCR4/ACKR3 axis and the STAT3 signaling pathway plays a crucial role in the progression of various diseases and neoplasms. Activation of the CXCL12/CXCR4/ACKR3 axis triggers the STAT3 pathway through multiple mechanisms, while the STAT3 pathway also regulates the expression of CXCL12. This review offers a thorough and systematic analysis of the reciprocal regulatory mechanisms between the CXCL12/CXCR4/ACKR3 signaling axis and the STAT3 signaling pathway in the context of diseases, particularly tumors. It explores the potential clinical applications in tumor treatment, highlighting possible therapeutic targets and novel strategies for targeted tumor therapy.

Identification of TNFRSF1A as a potential biomarker for osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a relatively rare malignant bone tumor in teenagers; however, its molecular mechanisms are not yet understood comprehensively.

OBJECTIVE

The study aimed to use necroptosis-related genes (NRGs) and their relationships with immune-related genes to construct a prognostic signature for OS.

METHODS

TARGET-OS was used as the training dataset, and GSE 16091 and GSE 21257 were used as the validation datasets. Univariate regression, survival analysis, and Kaplan-Meier curves were used to screen for hub genes. The immune-related targets were screened using immune infiltration assays and immune checkpoints. The results were validated using nomogram and decision curve analyses (DCA).

RESULTS

Using univariate Cox regression analysis, TNFRSF1A was screened from 14 NRGs as an OS prognostic signature. Functional enrichment was analyzed based on the median expression of TNFRSF1A. The prognosis of the TNFRSF1A low-expression group in the Kaplan-Meier curve was notably worse. Immunohistochemistry analysis showed that the number of activated T cells and tumor purity increased considerably. Furthermore, the immune checkpoint lymphocyte activation gene 3 (LAG-3) is a possible target for intervention. The nomogram accurately predicted 1-, 3-, and 5-year survival rates. DCA validated the model (C = 0.669).

Conclusion

TNFRSF1A can be used to elucidate the potential relationship between the immune microenvironment and NRGs in OS pathogenesis.

Caulis Spatholobi extracts inhibit osteosarcoma growth and metastasis through suppression of CXCR4/PI3K/AKT signaling

BACKGROUND

The therapeutic potential of Caulis Spatholobi (CS) extracts against various cancers has been well documented, yet its impact and mechanism in osteosarcoma (OS) remain unexplored. This study aims to elucidate the effects of CS extracts on the growth and metastasis of OS, along with its underlying molecular mechanism.

METHODS

The impact of CS extracts on the proliferative potential of two OS cell lines (Saos-2 and U2OS) was assessed using MTT and colony-formation assays. Additionally, the migratory and invasive capacities of OS cells were investigated through Transwell assays. The modulation of CXCR4 expression by CS extracts was evaluated using qRT-PCR and Western blotting. Furthermore, the influence of CS extracts on the activation of PI3K/Akt signaling was determined through Western blotting.

RESULTS

CS extracts exhibited a dose- and time-dependent inhibition of proliferation and colony formation in OS cells. Notably, CXCR4 expression was prominently observed in Saos-2 and U2OS, and treatment with CS extracts led to a dose-dependently reduction in CXCR4 levels. Silencing CXCR4 or inhibiting its function diminished the migratory and invasive capacities of OS cells. Conversely, the CS extracts induced suppression of OS cell migration and invasion was counteracted by CXCR4 overexpression. Mechanistically, CS extracts repressed PI3K/AKT signaling in OS cells by downregulating CXCR4 expression.

CONCLUSIONS

CS extracts mitigate the CXCR4/PI3K/AKT signaling-mediated growth and metastasis capacities of OS cells, thus might play an anti-tumor role in OS.

New emerging targets in osteosarcoma therapy: PTEN and PI3K/Akt crosstalk in carcinogenesis

Osteosarcoma (OS) is a malignant bone carcinoma that affects people in childhood and adulthood. The heterogeneous nature and chromosomal instability represent certain characteristics of OS cells. These cancer cells grow and migrate abnormally, making the prognosis undesirable for patients. Conventional and current treatments fail to completely eradicate tumor cells, so new therapeutics targeting genes may be considered. PI3K/Akt is a regulator of events such as growth, cell death, migration, and differentiation, and its expression changes during cancer progression. PTEN reduces PI3K/Akt expression, and its mutations and depletions have been reported in various tumors. Experimental evidence shows that there is upregulation of PI3K/Akt and downregulation of PTEN in OS. Increasing PTEN expression may suppress PI3K/Akt to minimize tumorigenesis. In addition, PI3K/Akt shows a positive association with growth, metastasis, EMT and metabolism of OS cells and inhibits apoptosis. Importantly, overexpression of PI3K/Akt causes drug resistance and radio-resistance and its level can be modulated by miRNAs, lncRNAs and circRNAs. Silencing PI3K/Akt by compounds and drugs can suppress OS. Here, we review in detail the function of the PTEN/PI3K/Akt in OS, revealing its biological function, function in tumor progression, resistance to therapy, and pharmacological significance.

Triptolide inhibits epithelial ovarian tumor growth by blocking the hedgehog/Gli pathway

Epithelial ovarian cancer (EOC), the most predominant subtype of ovarian cancer (OC), involves poor prognosis and exhibits high aggression. Triptolide (TPL), like other Chinese herbs, has historically played a significant role in modern medicine. The screening system based on Gli-dependent luciferase reporter activity assessed the effects of over 800 natural medicinal materials on hedgehog (Hh) signaling pathway activity and discovered that TPL had an excellent inhibitory effect on Hh signaling pathway activity. However, the significance and mechanism of TPL involvement in regulating the Hh pathway have not been well explored. Thus, this work aimed to understand better how TPL affects the Hh pathway activity, which, in turn, influences the biological behavior of EOC. Our findings observed that Smo agonist SAG-induced EOC cell proliferation, migration, and invasion were drastically reversed by TPL in a concentration-dependent pattern. Further evidence suggested that TPL promotes the degradation of Gli1 and Gli2 to inhibit the activity of the Hh signaling pathway by relying on Gli1 and Gli2 ubiquitination. Our in vivo studies also confirmed that TPL could significantly inhibit the tumor growth of EOC. Taken together, our results revealed that one of the antitumor mechanisms of TPL was the targeted inhibition of the Hh/Gli pathway.

CXCR4 inhibitor, AMD3100, down-regulates PARP1 expression and Synergizes with olaparib causing severe DNA damage in BRCA-proficient triple-negative breast cancer

Poly ADP-ribose polymerase inhibitor (PARPi) treatment is effective in triple-negative breast cancer (TNBC) with BRCA mutation. However, its efficacy in BRCA-proficient TNBC remains unexplored. It is, therefore, an exciting proposition to broaden the indication of PARPi for BRCA-proficient TNBC patients. Chemokine receptor (CXCR4) is a transmembrane G protein-coupled receptor, which is involved in cell migration, proliferation, apoptosis, and damage repair, and it initiates many signalling pathways. Although administration of CXCR4 inhibitor alone is not ideal as a target drug, it can play a strong synergistic role in combination with other drugs. We explored the effect of CXCR4 and PARP1 on tumour cell proliferation, migration, metastasis, and apoptosis in vitro and in vivo and found that a CXCR4 inhibitor, AMD3100, enhanced the anti-tumour effect of PARP1 inhibitor, olaparib, on BRCA-proficient TNBC. When CXCR4 was inhibited and silenced, DNA damage repair and DNA replication fork activity were suppressed by up-regulating caspase-3-mediated increase in PARP1 cleavage; in combination with the inhibition of PARP1, AMD3100 resulted in the accumulation of fatal DNA damage and induction of apoptosis. This combination regimen can be effective against BRCA-proficient TNBC.

Traditional Medicinal Plants as a Source of Inspiration for Osteosarcoma Therapy

Osteosarcoma is one of the most common types of bone cancers among paediatric patients. Despite the advances made in surgery, chemo-, and radiotherapy, the mortality rate of metastatic osteosarcoma remains unchangeably high. The standard drug combination used to treat this bone cancer has remained the same for the last 20 years, and it produces many dangerous side effects. Through history, from ancient to modern times, nature has been a remarkable source of chemical diversity, used to alleviate human disease. The application of modern scientific technology to the study of natural products has identified many specific molecules with anti-cancer properties. This review describes the latest discovered anti-cancer compounds extracted from traditional medicinal plants, with a focus on osteosarcoma research, and on their cellular and molecular mechanisms of action. The presented compounds have proven to kill osteosarcoma cells by interfering with different pathways: apoptosis induction, stimulation of autophagy, generation of reactive oxygen species, etc. This wide variety of cellular targets confer natural products the potential to be used as chemotherapeutic drugs, and also the ability to act as sensitizers in drug combination treatments. The major hindrance for these molecules is low bioavailability. A problem that may be solved by chemical modification or nano-encapsulation.

Therapeutic Potential of Triptolide in Treating Bone-Related Disorders

Triptolide, a diterpene triepoxide, is a pharmacologically active compound isolated from a Chinese medicinal herb Tripterygium wilfordii Hook F (TwHF). Triptolide has attracted considerable attention in recent times due to its multiple biological and pharmaceutical activities, with an emphasis on therapeutic importance in the treatment of diverse disorders. With essential medicinal implications, TwHF's extracts have been used as anti-inflammatory, antiproliferative, antioxidative, and immunosuppressive agents for centuries, with continuous and relevant modifications to date to enhance its utility in several diseases and pathophysiology. Here, in this review, we accentuate the studies, highlighting the effects of triptolide on treating bone-related disorders, both inflammatory and cancerous, particularly osteosarcoma, and their manifestations. Based on this review, future avenues could be estimated for potential research strategies, molecular mechanisms, and outcomes that might contribute toward reinforcing new dimensions in the clinical application of triptolide in treating bone-related disorders.

Recent and Ongoing Research into Metastatic Osteosarcoma Treatments

The survival rate for metastatic osteosarcoma has not improved for several decades, since the introduction and refinement of chemotherapy as a treatment in addition to surgery. Over two thirds of metastatic osteosarcoma patients, many of whom are children or adolescents, fail to exhibit durable responses and succumb to their disease. Concerted efforts have been made to increase survival rates through identification of candidate therapies via animal studies and early phase trials of novel treatments, but unfortunately, this work has produced negligible improvements to the survival rate for metastatic osteosarcoma patients. This review summarizes data from clinical trials of metastatic osteosarcoma therapies as well as pre-clinical studies that report efficacy of novel drugs against metastatic osteosarcoma in vivo. Considerations regarding the design of animal studies and clinical trials to improve survival outcomes for metastatic osteosarcoma patients are also discussed.

Triptolide: reflections on two decades of research and prospects for the future

Covering: 2000 to 2020 Triptolide is a bioactive diterpene triepoxide isolated from Tripterygium wilfordii Hook F, a traditional Chinese medicinal plant whose extracts have been used as anti-inflammatory and immunosuppressive remedies for centuries. Although triptolide and its analogs exhibit potent bioactivities against various cancers, and inflammatory and autoimmune diseases, none of them has been approved to be used in the clinic. This review highlights advances in material sourcing, molecular mechanisms, clinical progress and new drug design strategies for triptolide over the past two decades, along with some prospects for the future course of development of triptolide.

circHIPK3 Acts as Competing Endogenous RNA and Promotes Non-Small-Cell Lung Cancer Progression through the miR-107/BDNF Signaling Pathway

Circular RNAs (circRNAs) act as a crucial part in many human diseases, particularly in cancers. circRNA HIPK3 (circHIPK3) is a special circRNA that may participate in the oncogenesis of non-small-cell lung cancer (NSCLC), even though its latent regulatory mechanism is not very clear. Here, we studied the roles of circHIPK3 in NSCLC. qRT-PCR assay was applied to study the expression of circHIPK3 in NSCLC. The influence of circHIPK3 on NSCLC was estimated by silencing circHIPK3 and miR-107 mock transfection and brain-derived neurotrophic factor (BDNF) overexpression, and the correlation between circHIPK3, miR-107, and BDNF was evaluated by dual-luciferase reporter assay. The results showed that circHIPK3 expression was upregulated in NSCLC cells. circHIPK3 knockdown inhibited the migration and proliferation of NSCLC cells by promoting the expression of miR-107. circHIPK3 could be used as a miR-107 sponge to promote BDNF cell proliferation. The dual-luciferase reporter assay proved that miR-107 was the target of circHIPK3, and miR-107 had an interaction with the 3′untranslated region of BDNF. miR-107 overexpression inhibited BDNF-mediated NSCLC cell proliferation. These results indicate that circHIPK3 promotes tumor progression through a new circHIPK3/miR-107/BDNF axis, which offers potential markers and medical treatment for NSCLC.

Circular RNA circCCDC66 Contributes to Malignant Phenotype of Osteosarcoma by Sponging miR-338-3p to Upregulate the Expression of PTP1B

In recent years, the mechanism of cancer research has become hotspots of life science and medicine, especially due to the rapid development of molecular medicine and bioinformatics research. Similarly, the molecular mechanism also has received increasing attention in osteosarcoma (OS) research. Also, a considerable amount of research confirmed that circular RNAs (circRNAs) could regulate cancer cell growth and metastasis. This study aimed to explore the effect of a circRNA, circCCDC66, on OS and reveal its potential molecular mechanism. High circCCDC66 expression level was found in OS patient-derived tissue samples and OS cell lines by qRT-PCR. The abilities cell proliferation and metastatic of U2OS and SW1353 cells were then assessed by Cell Counting Kit-8 and transwell assay, respectively. The interaction between circCCDC66 and its target miRNAs were verified by the dual-luciferase reporter assay. Through functional experiments, we found that circCCDC66 knockdown promoted the inhibition of cell proliferation and metastatic of OS cell lines. From mechanistic perspective, circCCDC66 upregulated PTP1B by sponging miR-338-3p. Collectively, our findings demonstrated that circCCDC66 contributed to malignant behaviors of OS cells by miR-338-3p/PTP1B pathway, which suggested circCCDC66/miR-338-3p/PTP1B axis might be a potential therapeutic target.

Circular RNA circHIPK3 Promotes Cell Metastasis through miR-637/STAT3 Axis in Osteosarcoma

Recent studies have suggested that circular RNAs play an important role in the progression of various cancers. However, few studies have revealed the great value of circRNAs in the diagnosis and prognosis prediction of osteosarcoma (OS). In this study, we performed experiments with the human OS cell lines and the results showed that the expression of circHIPK3 in OS cell lines was significantly upregulated compared to that in the normal cell line. In addition, the results showed that circHIPK3 could promote the migration, invasion, and growth of OS cells. Furthermore, miR-637 was identified as a target of circHIPK3, while STAT3 was targeted by miR-637. circHIPK3 could promote STAT3 expression via interacting with miR-637 in OS cells. In conclusion, our research uncovered an important role of the circHIPK3/miR-637/STAT3 pathway in the migration and invasion of OS cells and suggested that circHIPK3 may be a prognostic marker and a promising therapeutic target for OS.

The prognostic impact of traditional Chinese medicine monomers on tumor-associated macrophages in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) accounts for 80%-85% of all lung malignancies and good diagnosis and prognosis of NSCLC are critical to the increase of its survival rate. Tumor-associated macrophages (TAM) abundantly present in numerous cancer types, and the role of TAMs in tumor biology and their prognostic value in cancer become major topics of interest. After various stimulations in the tumor microenvironment, TAMs develop into a M1 (tumor-inhibitory) phenotype or M2 (tumor-promoting) phenotype. Recent studies show that traditional Chinese medicine (TCM) monomers have markedly inhibitory actions for NSCLC through M1/M2 modulation. Due to the TCM monomers mainly covered five categories, i.e. terpenoids, flavonoids, polysaccharides, natural polyphenols, and alkaloids. Thus, we will discuss the regulation of TCM monomers on TAM involve in these five parts in this review. In addition, the potential role of TAMs as therapeutic targets will be discussed.

Triptolide inhibits PDGF-induced proliferation of ASMCs through G0/G1 cell cycle arrest and suppression of the AKT/NF-κB/cyclinD1 signaling pathway

Abnormal proliferation of airway smooth muscle cells (ASMCs) is a hallmark of airway remodeling. Platelet-derived growth factor (PDGF) is known to be a major stimulus inducing the proliferation of ASMCs. It has been reported that triptolide demonstrates protective effects against airway remodeling. In this study, we investigated the antiproliferative effects of triptolide on PDGF-induced ASMCs and its underlying mechanisms. Cell proliferation was determined using the Cell Counting Kit-8 (CCK-8) assay. Flow cytometry was used to study the influence of triptolide on cell cycle and apoptosis. Quantitative real-time PCR and Western blot analysis were employed to detect the expression of proliferating cell nuclear antigen (PCNA), cyclinD1 and cyclin dependent kinase 4 (CDK4). Proteins involved in the protein kinase B (AKT) and nuclear factor kappa B (NF-κB) signaling pathways were evaluated using Western blot analysis. Triptolide could significantly inhibit cell proliferation, induce cell cycle arrest in the G0/G1 phase, and reduce the expression of PCNA, cyclinD1, and CDK4 in PDGF-treated ASMCs. Levels of phosphorylated AKT, p65 and NF-κB inhibitor α (IκBα) stimulated by the presence of PDGF were markedly suppressed after triptolide treatment. Moreover, triptolide cotreatment with the phosphatidylinositol 3 kinase (PI3k) inhibitor, 2-(4-morpholinyl)-8-phenylchromone (LY294002), could further suppress the proliferation, NF-κB activation and cyclinD1 expression. Similar results were observed after triptolide cotreatment with the NF-κB inhibitor, ammonium pyrrolidinedithiocarbamate (PDTC). Our results suggest that triptolide could inhibit the PDGF-induced proliferation of ASMCs through G0/G1 cell cycle arrest and suppression of the AKT/NF-κB/cyclinD1 signaling pathway.

SDF-1/CXCR4 axis facilitates myeloid-derived suppressor cells accumulation in osteosarcoma microenvironment and blunts the response to anti-PD-1 therapy

Immune checkpoint inhibitors, such as anti-PD-1/PD-L1, are a novel class of inhibitors that function as a tumor suppressing factor via modulation of immune cell-tumor cell interaction. To date, PD-1/PD-L1 inhibitors have been approved for the treatment of specific types of tumors and obtained good clinical efficacy. However, patients with osteosarcoma showed poor response to anti-PD-1/PD-L1 therapy, the mechanism of which is not well understood. In this study, we found that osteosarcoma tissues were heavily infiltrated by myeloid-derived suppressor cells (MDSCs) which could inhibit cytotoxicity T cell (CTL) expansion. Further study revealed that the vast majority of tumor-infiltrating MDSCs were CXCR4 positive and could migrate toward an SDF-1 gradient. The binding of SDF-1 to its receptor CXCR4 results in the activation of downstream AKT pathway that mediates reduced apoptosis of MDSCs. We also demonstrated that AMD3100, a CXCR4 antagonist, has a synergistic effect with anti-PD-1 antibody in tumor treatment in a murine model of osteosarcoma. These findings provide the basis for establishing CXCR4 antagonist and PD-1/PD-L1 inhibitors co-administration as a novel therapeutic regimen for patients with osteosarcoma and hold great promise for improving the therapeutic effect of osteosarcoma.

CXCR4 in human osteosarcoma malignant progression. The response of osteosarcoma cell lines to the fully human CXCR4 antibody MDX1338

Osteosarcoma (OS) is the most frequent primary malignant tumour of bone and metastases occur in 30% of cases, the 5-year survival rate is 25–30%.

Although pre- and post-operative chemotherapy has improved prognosis in osteosarcoma (OS), high toxicity and natural and acquired drug-resistance are the first cause of treatment failure. The identification of new predictive and therapeutic biomarkers may increase drug sensitivity and better control localized and metastatic disease. By the evidence that CXCR4 receptor by binding its ligand CXCL12 activates downstream critical endpoints for tumour malignancy, we first studied human OS progression correlating CXCR4 expression in OS biopsy with patient clinical data. By Real-time PCR and immunoistochemistry we found that high levels of CXCR4 gene and protein expression significantly correlated with OS progression, emphasizing the role of CXCR4/CXCL12 axis in tumour prognosis. This was supported by univariate analyses that showed a higher probability of local and/or systemic relapse in OS patients with a high CXCR4 gene expression and a significant increase of metastasis risk associated with an increasing score of CXCR4 protein staining intensity. Secondarily, to study the role of CXCR4 as a target for new therapeutic strategies, we evaluated the response of OS cells to the fully human CXCR4 antibody, MDX1338. In the study we also included AMD3100, the most studied CXCR4 antagonist.

In CXCR4-positive OS cells cultured in CXCL12-rich BM-MCS-CM (bone marrow-derived mesenchymal stem conditioned medium), a decrease of cell proliferation up to 30%–40% of control was seen after drug exposure. However, an increase of apoptosis was seen in p53-positive U2OS and 143B after CXCR4 inhibitor incubation, while no changes were seen in treated SAOS-2 cells which also present a different labeling profile. The role of p53 in apoptotic response to CXCR4 inhibitors was confirmed by p53 silencing in U2OS cell line. Our data suggest that the response to anti-CXCR4 agents could be influenced by the genetic background and labeling profile which induces a different cross-talk between tumour cells and environment. The delay in cell cycle progression associated with increased apoptosis could sensitize p53-positive cells to conventional therapy and in vivo preclinical experiments are on going with the aim to suggest new combined target therapies in human OS.

Dual blockade of CXCL12-CXCR4 and PD-1-PD-L1 pathways prolongs survival of ovarian tumor-bearing mice by prevention of immunosuppression in the tumor microenvironment

Blockade of immune-checkpoint programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 can enhance effector T-cell responses. However, the lack of response in many patients to checkpoint-inhibitor therapies emphasizes the need for combination immunotherapies to pursue maximal antitumor efficacy. We have previously demonstrated that antagonism of C-X-C chemokine receptor type 4 (CXCR4) by plerixafor (AMD3100) can decrease regulatory T (Treg)-cell intratumoral infiltration. Therefore, a combination of these 2 therapies might increase antitumor effects. Here, we evaluated the antitumor efficacy of AMD3100 and anti-PD-1 (αPD-1) antibody alone or in combination in an immunocompetent syngeneic mouse model of ovarian cancer. We found that AMD3100, a highly specific CXCR4 antagonist, directly down-regulated the expression of both C-X-C motif chemokine 12 (CXCL12) and CXCR4 in vitro and in vivo in tumor cells. AMD3100 and αPD-1 significantly inhibited tumor growth and prolonged the survival of tumor-bearing mice when given as monotherapy. Combination of these 2 agents significantly enhanced antitumor effects compared with single-agent administration. Benefits of tumor control and animal survival were associated with immunomodulation mediated by these 2 agents, which were characterized by increased effector T-cell infiltration, increased effector T-cell function, and increased memory T cells in tumor microenvironment. Intratumoral Treg cells were decreased, and conversion of Treg cells into T helper cells was increased by AMD3100 treatment. Intratumoral myeloid-derived suppressor cells were decreased by the combined treatment, which was associated with decreased IL-10 and IL-6 in the ascites. Also, the combination therapy decreased suppressive leukocytes and facilitated M2-to-M1 macrophage polarization in the tumor. These results suggest that AMD3100 could be used to target the CXCR4-CXCL12 axis to inhibit tumor growth and prevent multifaceted immunosuppression alone or in combination with αPD-1 in ovarian cancer, which could be clinically relevant to patients with this disease.-Zeng, Y., Li, B., Liang, Y., Reeves, P. M., Qu, X., Ran, C., Liu, Q., Callahan, M. V., Sluder, A. E., Gelfand, J. A., Chen, H., Poznansky, M. C. Dual blockade of CXCL12-CXCR4 and PD-1-PD-L1 pathways prolongs survival of ovarian tumor-bearing mice by prevention of immunosuppression in the tumor microenvironment.

lncRNA LINC01296 regulates the proliferation, metastasis and cell cycle of osteosarcoma through cyclin D1

Accumulating evidence has indicated that aberrant expression of long non-coding RNAs (lncRNAs) is an important oncogenic factor. The aim of the present study was to investigate the role of LINC01296, an lncRNA that exerts a tumor-promoting function in many cancers, in the regulation of proliferation, metastasis and the cell cycle of osteosarcoma. The expression of LINC01296 in osteosarcoma tissues and adjacent healthy tissues of 30 patients was analyzed by quantitative real-time PCR (qRT-PCR). The relationship between LINC01296 expression and the survival of patients with osteosarcoma was also explored. The expression levels of LINC01296 in osteosarcoma cells and normal cells were compared. LINC01296 knockdown and overexpression were performed in MG63 and HOS8603 osteosarcoma cells by transfecting LINC01296 shRNA and an expression plasmid respectively, followed by investigation of the changes on cell proliferation, migration, apoptosis and cell cycle arrest. Western blotting was used to analyze the changes of cell cycle regulators. Cyclin D1 knockdown and overexpression were carried out to verify the interaction between LINC01296 and cyclin D1. LINC01296 overexpression was demonstrated as a biomarker of osteosarcoma, which was closely correlated with the poor survival of patients with osteosarcoma. A high expression of LINC01296 was observed in osteosarcoma cells, which was closely associated with enhanced proliferation, invasion, and migration of osteosarcoma cells. Cyclin D1 expression was positively correlated with the expression of LINC01296 in osteosarcoma cells. Cyclin D1 knockdown or overexpression played a deterministic role in mediating the effect of LINC01296 on osteosarcoma cells. LINC01296 is an oncogenic lncRNA in osteosarcoma. The proliferation, invasion and migration of osteosarcoma cells could be effectively retarded by inhibition of LINC01296. The cancer-promoting effect of LINC01296 on osteosarcoma was determined by cyclin D1.

Fordin: A novel type I ribosome inactivating protein from Vernicia fordii modulates multiple signaling cascades leading to anti-invasive and pro-apoptotic effects in cancer cells in vitro

Fordin, which is derived from Vernicia fordii, is a novel type I ribosome inactivating protein (RIP) with RNA N-glycosidase activity. In the present study, fordin was expressed by Escherichia coli and purified using nickel affinity chromatography. Previous studies have demonstrated RIP toxicity in a variety of cancer cell lines. To understand the therapeutic potential of fordin on tumors, the present study investigated the effects of fordin on the viability of several tumor and normal cell lines. The results demonstrated that fordin induced significant cytotoxicity in four cancer cell lines, compared with the normal cell line. Specifically, profound apoptosis and inhibition of cell invasion were observed following fordin exposure in U-2 OS and HepG2 cells; however, the molecular mechanism underlying the action of RIP remains to be fully elucidated. In the present study, it was found that the anticancer effects of fordin were associated with suppression of the nuclear factor (NF)-κB signaling pathway. In U-2 OS and HepG2 cells, fordin inhibited the expression of inhibitor of NF-κB (IκB) kinase, leading to downregulation of the phosphorylation level of IκB, which quelled the nuclear translocation of NF-κB. Fordin also reduced the mRNA and protein levels of NF-κB downstream targets associated with cell apoptosis and metastasis, particularly B-cell lymphoma-2-related protein A1 (Blf-1) and matrix metalloproteinase (MMP)-9. The inactivation of NF-κB and the reduction in the expression levels of Blf-1 and MMP-9 mediated by fordin were also confirmed by co-treatment with lipopolysaccharide or p65 small interfering RNA. These findings suggested a possible mechanism for the fordin-induced effect on tumor cell death and metastasis. The results of the present study demonstrated the multiple anticancer effects of fordin in U-2 OS and HepG2 cells, in part by inhibiting activation of the NF-κB signaling pathway.

JTC-801 exerts anti-proliferative effects in human osteosarcoma cells by inducing apoptosis

BACKGROUND

The research of G protein-coupled receptors (GPCRs) is a promising strategy for drug discovery. In cancer therapy, there is a need to discover novel agents that can inhibit proliferation and induce apoptosis in cancer cells. JTC-801 is a novel GPCR antagonist with the function of reversing pain and anxiety symptoms. This study aims to investigate the antitumor effects of JTC-801 on human osteosarcoma cells (U2OS) and elucidate the underlying mechanism.

MATERIALS AND METHODS

The Cell Counting Kit-8 assay was used to detect the viability of U2OS cells treated with JTC-801 in vitro. The cell apoptosis was evaluated using a flow cytometry assay with Annexin V-FITC/PI double staining. The inhibitory effect of JTC-801 on invasion and migration of U2OS cells were determined by the Transwell assays. Western blot assay was performed to measure the levels of proteins related to cell apoptosis and its mechanism.

RESULTS

The JTC-801 significantly decreased the viability of U2OS cells (p < .05) as a result of its anti-proliferative effect through induction of apoptosis associated with activation of BAX, Caspase-3 and down-regulating BCL-2 expression. The invasive and migratory cells were obviously reduced after JTC-801 treatment (p < .05). Further, the phosphorylated AKT, mTOR and active p70 S6 protein kinase in the PI3K/AKT signaling pathway were obviously lessened in the JTC-801 treated U2OS group (p < .05).

CONCLUSIONS

JTC-801 may exert osteosarcoma cell growth inhibition by promoting cell apoptosis, through PI3K/AKT signaling pathway participation.

Triptolide Suppresses Glomerular Mesangial Cell Proliferation in Diabetic Nephropathy Is Associated with Inhibition of PDK1/Akt/mTOR Pathway

Mesangial cell proliferation has been identified as a mainly contributing factor to glomerulosclerosis, which is typical of diabetic nephropathy. However, the specific mechanisms and therapies remain unclear. PDK1 is a critical regulator of cell proliferation, but the specific role of PDK1 in diabetic nephropathy has not been fully illuminated. In the current study, we demonstrated that triptolide (TP) ameliorated albuminuria in the high fat diet/STZ-induced diabetic rats. TP also suppressed the increased proliferating cell markers Ki-67 and PCNA in the kidney tissues. Our results of MTT and cell cycle analysis further confirmed that TP significantly inhibited mesangial cell proliferation, and the inhibition of PDK1/Akt/mTOR pathway might be the underlying mechanisms. In addition, we also found that the PDK1 activator (PS48) could reverse the cell proliferation inhibition role of TP. These data suggest that TP may be useful in prevention of diabetic glomerulosclerosis and that PDK1/Akt/mTOR pathway might be the underlying mechanism.

Regorafenib inhibited gastric cancer cells growth and invasion via CXCR4 activated Wnt pathway

AIM

Regorafenib is an oral small-molecule multi kinase inhibitor. Recently, several clinical trials have revealed that regorafenib has an anti-tumor activity in gastric cancer. However, only part of patients benefit from regorafenib, and the mechanisms of regorafenib's anti-tumor effect need further demonstrating. In this study, we would assess the potential anti-tumor effects and the underlying mechanisms of regorafenib in gastric cancer cells, and explore novel biomarkers for patients selecting of regorafenib.

METHODS

The anti-tumor effects of regorafenib on gastric cancer cells were analyzed via cell proliferation and invasion. The underlying mechanisms were demonstrated using molecular biology techniques.

RESULTS

We found that regorafenib inhibited cell proliferation and invasion at the concentration of 20μmol/L and in a dose dependent manner. The anti-tumor effects of regorafenib related to the decreased expression of CXCR4, and elevated expression and activation of CXCR4 could reverse the inhibition effect of regorafenib on gastric cancer cells. Further studies revealed that regorafenib reduced the transcriptional activity of Wnt/β-Catenin pathway and led to decreased expression of Wnt pathway target genes, while overexpression and activation of CXCR4 could attenuate the inhibition effect of regorafenib on Wnt/β-Catenin pathway.

CONCLUSIONS

Our findings demonstrated that regorafenib effectively inhibited cell proliferation and invasion of gastric cancer cells via decreasing the expression of CXCR4 and further reducing the transcriptional activity of Wnt/β-Catenin pathway.