New small molecules targeting apoptosis and cell viability in osteosarcoma

Transcriptome and single-cell analysis reveal disulfidptosis-related modification patterns of tumor microenvironment and prognosis in osteosarcoma

Osteosarcoma (OS) is the most common malignant bone tumor with high pathological heterogeneity. Our study aimed to investigate disulfidptosis-related modification patterns in OS and their relationship with survival outcomes in patients with OS. We analyzed the single-cell-level expression profiles of disulfidptosis-related genes (DSRGs) in both OS microenvironment and OS subclusters, and HMGB1 was found to be crucial for intercellular regulation of OS disulfidptosis. Next, we explored the molecular clusters of OS based on DSRGs and related immune cell infiltration using transcriptome data. Subsequently, the hub genes of disulfidptosis in OS were screened by applying multiple machine models. In vitro and patient experiments validated our results. Three main disulfidptosis-related molecular clusters were defined in OS, and immune infiltration analysis suggested high immune heterogeneity between distinct clusters. The in vitro experiment confirmed decreased cell viability of OS after ACTB silencing and higher expression of ACTB in patients with lower immune scores. Our study systematically revealed the underlying relationship between disulfidptosis and OS at the single-cell level, identified disulfidptosis-related subtypes, and revealed the potential role of ACTB expression in OS disulfidptosis.

Targeting CDK1 in cancer: mechanisms and implications

Cyclin dependent kinases (CDKs) are serine/threonine kinases that are proposed as promising candidate targets for cancer treatment. These proteins complexed with cyclins play a critical role in cell cycle progression. Most CDKs demonstrate substantially higher expression in cancer tissues compared with normal tissues and, according to the TCGA database, correlate with survival rate in multiple cancer types. Deregulation of CDK1 has been shown to be closely associated with tumorigenesis. CDK1 activation plays a critical role in a wide range of cancer types; and CDK1 phosphorylation of its many substrates greatly influences their function in tumorigenesis. Enrichment of CDK1 interacting proteins with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was conducted to demonstrate that the associated proteins participate in multiple oncogenic pathways. This abundance of evidence clearly supports CDK1 as a promising target for cancer therapy. A number of small molecules targeting CDK1 or multiple CDKs have been developed and evaluated in preclinical studies. Notably, some of these small molecules have also been subjected to human clinical trials. This review evaluates the mechanisms and implications of targeting CDK1 in tumorigenesis and cancer therapy.

Apoptosis-related genes-based prognostic signature for osteosarcoma

Osteosarcoma (OS) is a common malignant primary tumor of skeleton, especially in children and adolescents, characterized by high lung metastasis rate. Apoptosis has been studied in various tumors, while the prognostic role of apoptosis-related genes in OS has been seldom studied. Three OS related datasets were downloaded from Gene Expression Omnibus (GEO) database. Univariate Cox and LASSO Cox regression analysis identified optimal genes, which were used for building prognostic Risk score. Subsequent multivariate Cox regression analysis and Kaplan-Meier survival analysis determined the independent prognostic factors for OS. The immune cell infiltration was analyzed in CIBERSORT. Basing on 680 apoptosis-related genes, the OS patients could be divided into 2 clusters with significantly different overall survival. Among which, 6 optimal genes were identified to construct Risk score. In both training set (GSE21257) and validation set (meta-GEO dataset), high risk OS patients had significantly worse overall survival compared with the low risk patients. Besides, high Risk score was an independent poor prognostic factor for OS with various ages or genders. Three immune cells were differentially infiltrated between high and low risk OS patients. In conclusion, a six-gene (TERT, TRAP1, DNM1L, BAG5, PLEKHF1 and PPP3CB) based prognostic Risk score signature is probably conducive to distinguish different prognosis of OS patients.

The cancer-related transcription factor Runx2 combined with osteopontin: a novel prognostic biomarker in resected osteosarcoma

PURPOSE

Osteosarcoma is the most common primary bone cancer in children and young adults. Recent experimental evidence has indicated that Runx2/OPN axis play important roles in the metastasis of osteosarcoma cells. The present study aimed to explore their relationship and prognostic significance in surgically resected osteosarcoma.

METHODS

The expression of runt-related transcription factor2(Runx2) and osteopontin (OPN) in clinical specimens from 105 osteosarcoma patients were detected by immunohistochemistry. The correlations between Runx2, OPN, and clinicopathologic data were analyzed by Chi-square (χ²) tests. The prognostic values were determined by univariate and multivariate survival analysis. The accuracy of oncologic outcome prediction was evaluated by receiver-operating characteristics curves.

RESULTS

The results showed there is a significant positive correlation between Runx2 and OPN expression at protein levels (P = 0.015). Runx2 and OPN were both independent predictors for overall survival and metastasis-free survival. When Runx2 and OPN were taken into consideration together, the predictive range was extended and the sensitivity was improved, and more significant and better biomarkers for osteosarcoma metastasis and survival.

CONCLUSIONS

These results suggest that a combined Runx2/OPN expression could be a valuable independent predictor of tumor metastasis and survival in osteosarcoma patients.

Investigation of novel chemotherapeutics for feline oral squamous cell carcinoma

Feline oral squamous cell carcinomas (FOSCC) are highly aggressive neoplasms with short survival times despite multimodal treatment. FOSCC are similar to squamous cell carcinomas of the head and neck (SCCHN) in humans, which also present therapeutic challenges. The current study was undertaken to identify novel chemotherapeutics using FOSCC cell lines. A high throughput drug screen using 1,952 drugs was performed to identify chemotherapeutics for further investigation. Two of the drugs identified in the drug screen, actinomycin D and methotrexate, and two drugs with similar molecular targets to drugs found to be efficacious in the screening, dinaciclib and flavopiridol, were selected for further investigation. Drug inhibition profiles were generated for each drug and cell line using an MTS assay. In addition, the effects of the drugs of interest on cell cycle progression were analyzed via a propidium iodide DNA labeling assay. Changes in caspase-3/7 activity after treatment with each drug were also determined. The findings demonstrated effectiveness of the drugs at nanomolar concentrations with sensitivity varying across cell lines. With all of the drugs except for actinomycin D, evidence for G1 arrest was found. Dinaciclib and flavopiridol were demonstrated to induce apoptosis. The results of the study suggest that the selected drugs are potential candidates for developing novel chemotherapeutic approaches to FOSCC. Through these studies, novel therapeutic strategies for the treatment of FOSCC can be developed to provide better care for affected cats which can also serve as proof of concept studies to inform translational studies in SCCHN in humans.

Overexpression of p62 is associated with poor prognosis and aggressive phenotypes in osteosarcoma

p62 (also known as sequestosome 1) protein, is a small regulatory protein that accumulates in autophagy-defective cells that has been demonstrated to be involved in the prognosis and survival of patients with several types of cancer. However, to the best of our knowledge, there have been no such studies for osteosarcoma (OS). In the present study, the expression of p62 in 70 OS samples was determined using immunohistochemistry and its association with various clinicopathological factors was assessed. The results demonstrated that the overexpression of p62 protein was detected in 77.1% (54/70) samples, and the expression levels were significantly associated with tumor size (P=0.001), metastasis (P=0.036), clinical staging (P=0.003) and poor prognosis (P=0.0058). Furthermore, suppression of the p62 expression by short hairpin RNA interference in F5M2 and F4 cells lines led to decreased cell proliferation, migration and invasion in vitro. These results suggested that increased expression of p62 may be involved in OS progression, and therefore the excess expression of p62 may serve as a novel prognostic biomarker for patients with OS.

The natural sweetener metabolite steviol inhibits the proliferation of human osteosarcoma U2OS cell line

Steviol is the colonic metabolite of the natural sweetener steviol glycosides. It does not diffuse to the blood and the half maximal inhibitory concentration of steviol is longer compared with that of current chemotherapy agents, including 5-fluorouracil and doxorubicin. The present study demonstrated that steviol inhibits the proliferation of the human osteosarcoma U2OS cell line in a dose- and time-dependent manner, and that the inhibition rate is comparative with that of doxorubicin and 5-fluorouracil. The mechanism of this anticancer activity is also investigated. The results indicated that steviol inhibits U2OS cells through inducing G1 phase cell cycle arrest, downregulating the ability of colony formation via a mitochondrial apoptotic pathway, which was indicated by an increase of the Bax/Bcl-2 ratio and activation of cyclin-dependent kinase inhibitor 1, tumor protein 53 and cyclin-dependent kinase; whereas a Survivin and Caspase 3-independent mechanism was involved. Considering that steviol appears minimally in the plasma during metabolism, and possesses a median lethal dose of 100-fold greater compared with that of 5-fluorouracil, it may become a potential chemotherapy agent.

CPNE1 silencing inhibits the proliferation, invasion and migration of human osteosarcoma cells

Osteosarcoma (OS) is the most common primary malignancy of the bone affecting children and adolescents. Copine 1 (CPNE1) is a highly conserved calcium-dependent phospholipid-binding protein and may function in regulating signal transduction and membrane trafficking. In the present study, we investigated CPNE1 expression in osteosarcoma tissues and cells, and studied the effects of small interfering RNA (siRNA)-targeting CPNE1 on proliferation, metastasis and chemosensitivity of the osteosarcoma cells. The results demonstrated that CPNE1 was highly expressed in the osteosarcoma tissues and cell lines. Moreover, functional investigations confirmed that CPNE1 knockdown significantly inhibited cell proliferation, colony formation, invasion and metastasis in Saos-2 and HOS cells. Western blot analysis indicated that CPNE1 silencing downregulated the expression of many proteins associated with tumorigenesis and development, including Ras, MEK-1/2, WNT1, β-catenin, cyclin A1, IRAK2 and cIAP2. In addition, CPNE1 downregulation enhanced the sensitivity of Saos-2 cells towards cisplatin and adriamycin. The present study provides deep insight into the clinical use of lentiviral-mediated CPNE1 silencing for osteosarcoma therapy.

Withaferin-A Induces Apoptosis in Osteosarcoma U2OS Cell Line via Generation of ROS and Disruption of Mitochondrial Membrane Potential

Background

Withaferin-A (WF-A) is a well-known dietary compound isolated from Withania sominifera. It has tremendous pharmacological potential and has been shown to exhibit antiproliferative activity against several types of cancerous cells. Currently, the main focus of anti-cancer therapeutic development is to identify apoptosis inducing drug-like molecules. Osteosarcoma is a rare type of osteocancer, affecting human. The present study therefore focused on the evaluation of antitumor potential of WF-A against several osteosarcoma cell lines.

Materials and Methods:

MTT assay was used to evaluate WF-A against osteosarcoma cell lines and to calculate the IC₅₀. DAPI staining was used to confirm the apoptosis inducing potential of WF-A. Mitochondrial membrane potential, reactive oxygen species (ROS) assay, and Western blotting were used to confirm the basis of apoptosis.

Results:

The results revealed that that WF-A exhibited strong antiproliferative activity against all the cells lines, with IC₅₀ ranging from 0.32 to 7.6 μM. The lowest IC₅₀ (0.32 μM) was observed against U2OS cell line and therefore it was selected for further analysis. DAPI staining indicated that WF-A exhibited antiproliferative activity via induction of apoptosis. Moreover, WF-A induced ROS-mediated reduction in mitochondrial membrane potential ΔΨm) in a dose-dependent manner and activation of caspase-3 in osteosarcoma cells.

Conclusion

We propose that WF-A may prove a potent therapeutic agent for inducing apoptosis in osteosarcoma cell lines via generation of ROS and disruption of mitochondrial membrane potential.

SUMMARY

WF-A exhibits strong anticancer activity against osteosarcoma cell lines

Antiproliferative activity of WF-A is via induction of apoptosis

WF-A induced ROS-mediated reduction in mitochondrial membrane potential

WF-A induced expression of caspase-3 in osteosarcoma cells.

Abbreviations used: WA: Withaferin A; ROS: Reactive oxygen species; OS: Osteosarcoma; MMP: Mitochondrial membrane potential.

PLA2G16 promotes osteosarcoma metastasis and drug resistance via the MAPK pathway

The prognosis of metastatic osteosarcoma is dismal and a better understanding of the mechanisms underlying disease progression is essential to improve treatment options and patient outcomes. We previously demonstrated Pla2g16 overexpression in mouse osteosarcoma contributes to metastasis phenotypes and increased expression of PLA2G16 is associated with metastasis and poor prognosis in human tumors. To further examine the mechanisms through which PLA2G16 contributes to human osteosarcoma metastasis and explore the potential of PLA2G16 as a therapeutic target in osteosarcoma, we generated a panel of human osteosarcoma cell lines expressing different levels of PLA2G16. The functional analyses of these cell lines demonstrated high levels of PLA2G16 expression increased osteosarcoma cell migration, invasion, clonogenic survival, and anchorage-independent colony formation. Importantly, this activity was dependent on the phospholipase activity of PLA2G16. Additionally, PLA2G16 overexpression decreased the sensitivity of cells to a panel of chemotherapeutic agents. Analysis of downstream pathways revealed the pro-metastasis functions of PLA2G16 were mediated through the MAPK pathway, as knockdown of PLA2G16 decreased ERK1/2 phosphorylation and pharmacological inhibition of MEK significantly repressed PLA2G16 mediated cell migration and clonogenic survival. Furthermore, PLA2G16 overexpression promoted xenograft tumor growth in vivo, and these tumors exhibit increased ERK1/2 phosphorylation. Lastly, the expression of PLA2G16 is strongly correlated with the increased ERK1/2 phosphorylation in human osteosarcoma samples, and the combined lesions are associated with reduced overall and metastasis-free survival. Collectively, these results demonstrate increased PLA2G16 expression activates the MAPK pathway to enhance osteosarcoma metastasis and may be a novel therapeutic target for these cancers.

Cell apoptosis, autophagy and necroptosis in osteosarcoma treatment

Osteosarcoma is the most common primary bone tumor in children and adolescents. Although combined therapy including surgery and multi-agent chemotherapy have resulted in great improvements in the overall survival of patients, chemoresistance remains an obstacle for the treatment of osteosarcoma. Molecular targets or effective agents that are actively involved in cell death including apoptosis, autophagy and necroptosis have been studied. We summarized how these agents (novel compounds, miRNAs, or proteins) regulate apoptotic, autophagic and necroptotic pathways; and discussed the current knowledge on the role of these new agents in chemotherapy resistance in osteosarcoma.

MiR-34a and miR-203 Inhibit Survivin Expression to Control Cell Proliferation and Survival in Human Osteosarcoma Cells

Elevated expression of survivin is observed in a number of cancer types, including human osteosarcoma. Few studies have demonstrated that survivin expression levels can be considered an independent predictor of survival for human osteosarcoma patients. However, the underlying molecular mechanisms of survivin in the process of human osteosarcoma carcinogenesis remain unclear. In the current study, we evaluated the biological effects of survivin knockdown on osteosarcoma cell proliferation, colony formation rate, and sensitivity to the chemotherapeutic agent cisplatin. We found that two different osteosarcoma cell lines, U2OS and Saos-2, have relatively higher expression levels of survivin, and specific knockdown of survivin resulted in a number of effects, such as inhibition of cell proliferation, decreased colony formation rate, cell cycle arrest at G2/M phase, induction of apoptosis, and increased sensitivity to cisplatin. In addition, we identified two microRNAs, miR-34a and miR-203, that are aberrantly expressed in human osteosarcoma cells and specifically target survivin by inhibiting its expression, therefore repressing osteosarcoma cell maintenance and proliferation.

Upregulation of the growth arrest-specific-2 in recurrent colorectal cancers, and its susceptibility to chemotherapy in a model cell system

Colorectal cancer (CRC) is one of the most common life-threatening malignances worldwide. CRC relapse markedly decreases the 5-year survival of patients following surgery. Aberrant expression of genes involved in pathways regulating the cell cycle, cell proliferation, or cell death are frequently reported in CRC tumorigenesis. We hypothesized that genes involved in CRC relapse might serve as prognostic indicators. We first evaluated the significance of gene sequences in the feces of patients with CRC relapse by consulting a public database. Tumorigenesis of target tissues was tested through tumor cell growth, cell cycle regulation, and chemotherapeutic efficacy. We found a highly significant correlation between CRC relapse and growth arrest-specific 2 (GAS2) gene expression. Based on cell models, the overexpressed GAS2 was associated with cellular growth rate, cell cycle regulation, and with chemotherapeutic sensitivity. Cell division was impaired by treating cells with 2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]-propionic acid (XK469), even when the cells were overexpressing GAS2. Thus, downregulation of GAS2 expression might control CRC relapse after curative resection. GAS2 could serve as a noninvasive marker from the feces of patients with prediagnosed CRC. Our findings suggest that GAS2 could have potential clinical applications for predicting early CRC relapse after radical resection, and that XK469 might impair tumor cell division by reducing GAS2 expression or blocking its cellular translocation. This will help in selecting the best therapeutic option, 5-fluorouracil in combination with XK469, for patients overexpressing GAS2 in CRC cells. Thus, GAS2 might act as a prognostic biomolecule and potential therapeutic target in patients with CRC relapse.