Oleandrin sensitizes human osteosarcoma cells to cisplatin by preventing degradation of the copper transporter 1

p53 inhibits CTR1-mediated cisplatin absorption by suppressing SP1 nuclear translocation in osteosarcoma

Background

Osteosarcoma (OS) is a malignant bone tumor mainly affecting children and young adolescents. Cisplatin is a first-line chemotherapy drug for OS, however, drug resistance severely limits the survival of OS. Nevertheless, cellular factors in cisplatin resistance for OS remain obscure. In this study, the function and potential mechanism of p53 in cisplatin absorption were explored in OS cells.

Methods

The CRISPR-Cas9 gene editing technology was performed to obtain p53 gene knock-out U2OS cells. The p53 over-expression 143B cell line was established by lentivirus-mediated virus infection. Moreover, the functions of p53 and CTR1 in cisplatin absorption were assessed by inductively coupled plasma mass spectrometry (ICP-MS) through CTR1 over-expression and knock-down. Further, the DNA binding activity of SP1 on CTR1 gene promoter was determined by dual-luciferase assay and chromatin immunoprecipitation (ChIP) assay. The functional regulation of p53 on SP1 was studied by nucleocytoplasmic separation assay and electrophoretic mobility shift assay (EMSA). The interaction between p53 and SP1 was verified by Co-Immunoprecipitation assay.

Results

Under cisplatin treatment, p53 knock-out promoted CTR1 expression and cisplatin uptake, while p53 overexpression inhibited CTR1 expression and cisplatin uptake. Moreover, p53 regulated CTR1 level not by binding to CTR1 promoter directly but by suppressing the nuclear translocation of transcription factor specificity protein 1 (SP1). It was verified that SP1 is directly bound with CTR1 promoter. SP1 overexpression stimulated CTR1 expression, and SP1 knock-down attenuated CTR1 expression.

Conclusion

The p53 might function as a negative regulator in CTR1 mediated cisplatin absorption, and the p53-SP1-CTR1 axis is a target for cisplatin resistance.

Cisplatin-induced ototoxicity: From signaling network to therapeutic targets

Administration of cisplatin, a common chemotherapeutic drug, has an inevitable side effect of sensorineural hearing loss. The main etiologies are stria vascularis injury, spiral ganglion degeneration, and hair cell death. Over several decades, the research scope of cisplatin-induced ototoxicity has expanded with the discovery of the molecular mechanism mediating inner ear cell death, highlighting the roles of reactive oxygen species and transport channels for cisplatin uptake into inner ear cells. Upon entering hair cells, cisplatin disrupts organelle metabolism, induces oxidative stress, and targets DNA to cause intracellular damage. Recent studies have also reported the role of inflammation in cisplatin-induced ototoxicity. In this article, we preform a narrative review of the latest reported molecular mechanisms of cisplatin-induced ototoxicity, from extracellular to intracellular. We build up a signaling network starting with cisplatin entering into the inner ear through the blood labyrinth barrier, disrupting cochlear endolymph homeostasis, and activating inflammatory responses of the outer hair cells. After entering the hair cells, cisplatin causes hair cell death via DNA damage, redox system imbalance, and mitochondrial and endoplasmic reticulum dysfunction, culminating in programmed cell death including apoptosis, necroptosis, autophagic death, pyroptosis, and ferroptosis. Based on the mentioned mechanisms, prominent therapeutic targets, such as channel-blocking drugs of cisplatin transporter, construction of cisplatin structural analogues, anti-inflammatory drugs, antioxidants, cell death inhibitors, and others, were collated. Considering the recent research efforts, we have analyzed the feasibility of the aforementioned therapeutic strategies and proposed our otoprotective approaches to overcome cisplatin-induced ototoxicity.

Glycoside oleandrin downregulates toll-like receptor pathway genes and associated miRNAs in human melanoma cells

Melanoma accounts for the majority of skin cancer-related deaths. Nerium oleander is a plant known to be toxic and consumed due to the cardiac glycosides it contains. Oleandrin is a cardiac glycoside obtained from of N. oleander. Beside capable of inhibiting proliferation and metastasis of cancer cells, cardiac glycoside derivative compounds cause cardiovascular side effects. Because of cardiovascular toxicity of clinically used cardiac glycosides, it is necessary to investigate cardiac glycoside derivative compounds capable of inhibiting proliferation and metastasis of cancer cells. It is known that oleandrin has anticarcinogenic effects in other cancers. Previous studies have shown that toll-like receptors (TLRs) and their related microRNAs (miRNAs) are associated with cancer. Therefore, aim was to investigate the effect of oleandrin on genes and miRNAs associated with TLRs in A375 melanoma cells in this study. The effects of oleandrin on cell viability, cytokines, apoptosis were evaluated using XTT, ELISA and TUNEL analyses, respectively. The effect of oleandrin on expression of TLR genes and 5 associated miRNAs in A375 cells has been determined by qRT-PCR. In addition, the levels of MyD88, TLR2 and TLR4 proteins were analyzed by western blot method. ELISA indicated that oleandrin treatment (47 nM at 48 h) reduced the level of proinflammatory cytokine IFNG. TUNEL analysis showed that apoptosis rate was significantly increased in the oleandrin dose group. According to qRT-PCR results, there was a significant decrease in IRAK1, IRAK4, MyD88, TLR2-TLR7 and TRAF3 expressions in the oleandrin treated group compared to the control (untreated cell). Also, a significant decrease in TLR4 protein expression has been observed. In addition, oleandrin significantly downregulated the levels of hsa-miRNA-146a-5p and hsa-miRNA-21-5p. In conclusion, it has been observed that oleandrin has an effect on TLR pathway-related genes and miRNAs in melanoma cells. We show that TLRs pathways and hsa-miR-146a-5p and hsa-miR-21-5p can participate in the oleandrin molecular mechanism of action.

Glucose restriction induces ROS-AMPK-mediated CTR1 expression and increases cisplatin efficiency in NSCLC

Cisplatin is one of the principal platinum-based chemotherapeutic agents for many types of cancer, including non-small-cell lung cancer (NSCLC). Copper transporter 1 (CTR1) plays a significant role in increasing cellular cisplatin uptake and sensitivity. The current study found that glucose restriction upregulated AMPK (AMP-activated protein kinase) through reactive oxygen species (ROS) to induce CTR1 expression in NSCLC cells. Direct upregulation of ROS levels also activated AMPK expression. The changes in CTR1 expression were consistent with glucose concentrations and AMPK expression. Feeding a low-carbohydrate ketogenic diet (a glucose restriction diet) to a severe combined immune deficiency (SCID) mouse xenograft model significantly enhanced the efficacy of cisplatin. The tumor size was significantly smaller in the group treated with cisplatin plus the low-carbohydrate ketogenic diet than in the group treated with cisplatin alone. Survival was longer in mice treated with the low-carbohydrate ketogenic diet than in the controls. Mice fed the low-carbohydrate ketogenic diet showed increased expression of CTR1 and AMPK in tumor tissues. These results suggest a novel mechanism whereby glucose restriction induces ROS-AMPK-mediated CTR1 expression in NSCLC, indicating glucose restriction as an effective adjuvant NSCLC therapy.

The functional roles of the circRNA/Wnt axis in cancer

CircRNAs, covalently closed noncoding RNAs, are widely expressed in a wide range of species ranging from viruses to plants to mammals. CircRNAs were enriched in the Wnt pathway. Aberrant Wnt pathway activation is involved in the development of various types of cancers. Accumulating evidence indicates that the circRNA/Wnt axis modulates the expression of cancer-associated genes and then regulates cancer progression. Wnt pathway-related circRNA expression is obviously associated with many clinical characteristics. CircRNAs could regulate cell biological functions by interacting with the Wnt pathway. Moreover, Wnt pathway-related circRNAs are promising potential biomarkers for cancer diagnosis, prognosis evaluation, and treatment. In our review, we summarized the recent research progress on the role and clinical application of Wnt pathway-related circRNAs in tumorigenesis and progression.

Combination Therapy of Cisplatin and other Agents for Osteosarcoma: A Review

Background:

Osteosarcoma is the most common type of primary bone tumor in children and adolescents, which is associated with rapid progression and poor prognosis. Multimodal therapy is the most common approach utilized for osteosarcoma management, such as the application of chemotherapy in combination with surgery or radiation therapy. Cisplatin is one of the predominantly used chemotherapeutic agents for osteosarcoma. Optimally, it is employed in combination with other chemotherapeutic drugs along with surgery or radiation therapy. Despite the availability of numerous treatment approaches, the patient survival rate has not definitively improved over the past three decades.

Methods:

We have summarized all findings regarding the combination of cisplatin with other chemotherapeutic agents as well as with phytochemical compounds.

Results:

A combination of cisplatin with a phytochemical compound synergistically enhances the killing effect of cisplatin on osteosarcoma cells with fewer side effects compared to combination with other chemotherapeutic agents.

Conclusion:

Conclusively, a combination of cisplatin with selected chemotherapeutic drugs has been shown to be effective. However, the unchanged survival rate has posed an urge to search for a new combination regimen. As a collaborative effort to substantiate the therapeutic efficacy, the combination with phytochemical compounds shows a promising response both in vitro as well as in the preclinical study.

Cisplatin-induced ototoxicity: Updates on molecular mechanisms and otoprotective strategies

Cisplatin is a highly effective antitumor drug generally used in the treatment of solid malignant tumors. However, cisplatin causes severe side effects such as bone marrow depression, nephrotoxicity, and ototoxicity, thus limiting its clinical application. The incidence of ototoxicity induced by cisplatin ranges from 20% to 70%, and it usually manifests as a progressive, bilateral and irreversible hearing loss. Although the etiology of cisplatin-induced ototoxicity remains unclear, an increasing body of evidence suggests that the ototoxicity of cisplatin is mainly related to the production of reactive oxygen species and activation of apoptotic pathway in cochlear tissues. Many drugs have been well proved to protect cisplatin-induced hearing loss in vitro and in vivo. However, the anti-tumor effect of cisplatin is also weakened by systemic administration of those drugs for hearing protection, especially antioxidants. Therefore, establishing a local administration strategy contributes to the otoprotection without affecting the effect of cisplatin. This review introduces the pathology of ototoxicity caused by cisplatin, and focuses on recent developments in the mechanisms and protective strategies of cisplatin-induced ototoxicity.

Oleandrin, a cardiac glycoside, induces immunogenic cell death via the PERK/elF2α/ATF4/CHOP pathway in breast cancer

Chemotherapeutic agents have been linked to immunogenic cell death (ICD) induction that is capable of augmenting anti-tumor immune surveillance. The cardiac glycoside oleandrin, which inhibits Na⁺/K⁺-ATPase pump (NKP), has been shown to suppress breast cancer growth via inducing apoptosis. In the present study, we showed that oleandrin treatment triggered breast cancer cell ICD by inducing calreticulin (CRT) exposure on cell surface and the release of high-mobility group protein B1 (HMGB1), heat shock protein 70/90 (HSP70/90), and adenosine triphosphate (ATP). The maturation and activation of dendritic cells (DCs) were increased by co-culturing with the oleandrin-treated cancer cells, which subsequently enhanced CD8⁺ T cell cytotoxicity. Murine breast cancer cell line EMT6 was engrafted into BALB/c mice, and tumor-bearing mice were administered with oleandrin intraperitoneally every day. Oleandrin inhibited tumor growth and increased tumor infiltrating lymphocytes including DCs and T cells. Furthermore, the differential mRNA expression incurred by oleandrin was investigated by mRNA sequencing and subsequently confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Mechanistically, oleandrin induced endoplasmic reticulum (ER) stress-associated, caspase-independent ICD mainly through PERK/elF2α/ATF4/CHOP pathway. Pharmacological and genetic inhibition of protein kinase R-like ER kinase (PERK) suppressed oleandrin-triggered ICD. Taken together, our findings showed that oleandrin triggered ER stress and induced ICD-mediated immune destruction of breast cancer cells. Oleandrin combined with immune checkpoint inhibitors might improve the efficacy of immunotherapy.

Cytotoxicity of Oleandrin Is Mediated by Calcium Influx and by Increased Manganese Uptake in Saccharomyces cerevisiae Cells

Oleandrin, the main component of Nerium oleander L. extracts, is a cardiotoxic glycoside with multiple pharmacological implications, having potential anti-tumoral and antiviral characteristics. Although it is accepted that the main mechanism of oleandrin action is the inhibition of Na⁺/K⁺-ATPases and subsequent increase in cell calcium, many aspects which determine oleandrin cytotoxicity remain elusive. In this study, we used the model Saccharomyces cerevisiae to unravel new elements accounting for oleandrin toxicity. Using cells expressing the Ca²⁺-sensitive photoprotein aequorin, we found that oleandrin exposure resulted in Ca²⁺ influx into the cytosol and that failing to pump Ca²⁺ from the cytosol to the vacuole increased oleandrin toxicity. We also found that oleandrin exposure induced Mn²⁺ accumulation by yeast cells via the plasma membrane Smf1 and that mutants with defects in Mn²⁺ homeostasis are oleandrin-hypersensitive. Our data suggest that combining oleandrin with agents which alter Ca²⁺ or Mn²⁺ uptake may be a way of controlling oleandrin toxicity.

Oleandrin: A bioactive phytochemical and potential cancer killer via multiple cellular signaling pathways

Nerium oleander, a member of family Apocynaceae, is commonly known as Kaner in various countries of Asia and Mediterranean region. This plant has been renowned to possess significant therapeutic potential due to its various bioactive compounds which have been isolated from this plant e.g., cardiac glycosides, oleandrin, α-tocopherol, digitoxingenin, urosolic acid, quercetin, odorosides, and adigoside. Oleandrin, a saponin glycoside is one of the most potent and pharmacologically active phytochemicals of N. oleander. Its remarkable pharmacotherapeutic potential have been interpreted as anticancer, anti-inflammatory, anti-HIV, neuroprotective, antimicrobial and antioxidant. This particular bioactive entity is known to target the multiple deregulated signaling cascades of cancer such as NF-κB, MAPK, and PI3K/Akt. The main focus of the current study is to comprehend the action mechanisms of oleandrin against various pathological conditions. The current review is a comprehensive summary to facilitate the researchers to understand the pharmacological position of the oleandrin in the arena of drug discovery, representing this compound as a new drug candidate for further researches. Moreover, in vivo and in silico based studies are required to explore the mechanistic approaches regarding the pharmacokinetics and biosafety profiling of this compound to completely track its candidature status in natural drug discovery.

PTBP1 modulates osteosarcoma chemoresistance to cisplatin by regulating the expression of the copper transporter SLC31A1

Chemoresistance is the main obstacle of treatment in patients with osteosarcoma. RNA‐binding protein PTBP1 has been identified as an oncogene in various cancers. However, the role of PTBP1 in osteosarcoma, especially in chemoresistant osteosarcoma, and the underlying mechanism remain unclear. In this study, we aimed to explore the functions of PTBP1 in chemoresistance of osteosarcoma. We found that PTBP1 was significantly increased in chemotherapeutically insensitive osteosarcoma tissues and cisplatin‐resistant osteosarcoma cell lines (MG‐63_CISR and U‐2OS_CISR) as compared to chemotherapy‐sensitive osteosarcoma tissues and cell lines. Knock‐down of PTBP1 can enhance the anti‐proliferation and apoptosis‐induced effects of cisplatin in MG‐63_CISR and U‐2OS_CISR cells. Moreover, PTBP1 knock‐down significantly up‐regulated the expression of the copper transporter SLC31A1, as indicated by transcriptome sequencing. Through RNA immunoprecipitation, dual‐luciferase reporter assay and RNA stability detection, we confirmed that PTBP1 binds to SLC31A1 mRNA and regulates the expression level of SLC31A1 by affecting mRNA stability. Additionally, SLC31A1 silencing abrogated the chemosensitizing effect of PTBP1 knock‐down in MG‐63_CISR and U‐2OS_CISR cells. Using a nude mouse xenograft model, we further confirmed that PTBP1 knock‐down enhanced chemoresistant osteosarcoma responsiveness to cisplatin treatment in vivo. Collectively, the present study suggests that PTBP1 is a crucial determinant of chemoresistance in osteosarcoma.

IL-7-Mediated IL-7R-JAK3/STAT5 signalling pathway contributes to chemotherapeutic sensitivity in non-small-cell lung cancer

Objectives

The chemotherapy drug resistance is a major challenge for non‐small‐cell lung cancer (NSCLC) treatment. Combination of immunotherapy and chemotherapy has shown promise for cancer. The goal of this study was to evaluate the anti‐tumour efficacy of interleukin‐7 (IL‐7) combining cisplatin against NSCLC.

Materials and Methods

Cell proliferation was analysed using CCK‐8 assay, EdU proliferation assay and colony‐forming assay. Cell apoptosis was evaluated using HOECHST 33342 assay and flow cytometry. The protein expression levels were analysed by Western blot. The blocking antibody against the IL‐7 receptor and the inhibitors of STAT5 and JAK3 were used to investigate the pathway involved. A xenograft model was established to assess the anti‐tumour efficacy of IL‐7 combining cisplatin in vivo.

Results

Here we found IL‐7R was increased in A549/DDP cells compared with A549 cells. The block of IL‐7R reversed the inhibitory effects of IL‐7 combined with cisplatin and decreased the numbers of apoptosis cells induced by treatment of IL‐7 combined with cisplatin. The JAK3 inhibitor and STAT5 inhibitor were used to identify the pathway involved. The results showed that JAK3/STAT5 pathway was involved in enhancing role of cisplatin sensitivity of NSCLC cells by IL‐7. In vivo, cisplatin significantly inhibited tumour growth and IL‐7 combined with cisplatin achieved the best therapeutic effect.

Conclusion

Together, IL‐7 promoted the sensitivity of NSCLC cells to cisplatin via IL‐7R‐JAK3/STAT5 signalling pathway.