Gene therapy for osteosarcoma: steps towards clinical studies

Identification of MAP3K15 as a potential prognostic biomarker and correlation with immune infiltrates in osteosarcoma

Background

Osteosarcoma (OS) is a type of primary malignant tumor, and increasing evidence shows the clinical benefits of immunotherapy in treating OS. However, the lack of comprehensive studies on the complex OS immune microenvironment hinders the application of immunotherapy. Thus, this study aimed to systematically explore the immune characteristics of OS and identify novel biomarkers for OS treatment.

Methods

We systematically studied the immune score and proportions of infiltrating immune cells in OS in the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO) databases using the ESTIMATE and CIBERSORT algorithms. Differential expression and functional analyses were used to identify dysregulated genes and explore their functions. Survival and Cox regression analyses were applied to establish an immune-related prognostic signature. Additionally, qPCR and immunohistochemistry were performed to validate the results.

Results

A total of 103 differentially expressed immune genes (DEIGs) were found in the TARGET-OS and GSE39058 databases, and these DEIGs were mainly enriched in leukocyte proliferation, leukocyte differentiation, osteoclast differentiation, natural killer (NK) cell-mediated cytotoxicity, and the adaptive immune system. A predictive signature was constructed based on the survival analysis, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.65. Moreover, we found that mitogen-activated protein kinase kinase kinase 15 (MAP3K15) can predict the prognosis of patients with OS and is closely related to CD4⁺ T cells and macrophages. The OS patients with high MAP3K15 expression had a significantly poorer prognosis.

Conclusions

Our study found that MAP3K15, whose expression level is closely related to immune activity in tumors, is a critical immune-related biomarker, and our findings may provide a basis for OS immunotherapy.

Osteosarcoma: a review of current and future therapeutic approaches

Osteosarcoma (OS) is the most common primary bone malignancy that affects children and young adults. OS is characterized by a high degree of malignancy, strong invasiveness, rapid disease progression, and extremely high mortality rate; it is considered as a serious threat to the human health globally. The incidence of OS is common in the metaphysis of long tubular bones, but rare in the spine, pelvis, and sacrum areas; moreover, majority of the OS patients present with only a single lesion. OS has a bimodal distribution pattern, that is, its incidence peaks in the second decade of life and in late adulthood. We examine historical and current literature to present a succinct review of OS. In this review, we have discussed the types, clinical diagnosis, and modern and future treatment methods of OS. The purpose of this article is to inspire new ideas to develop more effective therapeutic options.

dsRNA Uptake in Plant Pests and Pathogens: Insights into RNAi-Based Insect and Fungal Control Technology

Efforts to develop more environmentally friendly alternatives to traditional broad-spectrum pesticides in agriculture have recently turned to RNA interference (RNAi) technology. With the built-in, sequence-specific knockdown of gene targets following delivery of double-stranded RNA (dsRNA), RNAi offers the promise of controlling pests and pathogens without adversely affecting non-target species. Significant advances in the efficacy of this technology have been observed in a wide range of species, including many insect pests and fungal pathogens. Two different dsRNA application methods are being developed. First, host induced gene silencing (HIGS) harnesses dsRNA production through the thoughtful and precise engineering of transgenic plants and second, spray induced gene silencing (SIGS) that uses surface applications of a topically applied dsRNA molecule. Regardless of the dsRNA delivery method, one aspect that is critical to the success of RNAi is the ability of the target organism to internalize the dsRNA and take advantage of the host RNAi cellular machinery. The efficiency of dsRNA uptake mechanisms varies across species, and in some uptake is negligible, rendering them effectively resistant to this new generation of control technologies. If RNAi-based methods of control are to be used widely, it is critically important to understand the mechanisms underpinning dsRNA uptake. Understanding dsRNA uptake mechanisms will also provide insight into the design and formulation of dsRNAs for improved delivery and provide clues into the development of potential host resistance to these technologies.

Long non-coding RNA TUSC7 suppresses osteosarcoma by targeting miR-211

Long non-coding RNAs (lncRNAs) play a critical role in regulating cancer progression and metastasis. LncRNA tumor suppressor candidate 7 (TUSC-7) was shown to be a tumor suppressor in osteosarcoma. However, the regulation mechanism of TUSC-7 in osteosarcoma is unknown. Bioinformatics analysis showed that TUSC7 specifically binds to miR-211. MiR-211 was up-regulated in osteosarcoma and negatively correlated with the expression of TUSC7. miR-211 expression was inhibited remarkably by TUSC7 overexpression and the reciprocal inhibition exists between TUSC7 and miR-211. RNA pull-down and luciferase reporter assays were used to validate the sequence-specific correlation between miR-211 and TUSC7. TUSC7 inhibited the proliferation, migration of osteosarcoma cells and promoted cellular apoptosis, which is largely mediated by miR-211. We conclude that the TUSC7 acted as a tumor suppressor gene, which is negatively regulated by miR-211. Our study could suggest a potentially novel therapeutic strategy against osteosarcoma.

miR-145-loaded micelleplexes as a novel therapeutic strategy to inhibit proliferation and migration of osteosarcoma cells

Osteosarcoma (OS), the main primary malignancy of bone, is the second leading cause of cancer in children and young adults. Despite the advances in modern treatments, the 5-year survival rate is retained in 60-70%, since the conventional treatment options available are associated with relapse, chemoresistance, and development of metastases, which frequently lead to patients death. In this regard, there is an increasing need to search and develop novel and alternative therapeutic approaches. Concerning this, gene therapy appears as an innovative and promising treatment option. This therapeutic option aims to deliver genetic material, through nanosystems, to repress or replace the expression of mutated genes involved in important regulatory pathways. To attain this goal, gene therapy is decidedly dependent on the efficiency of utilized vectors, constituting such a very important parameter to take in consideration. In this work, the main goal was centered on the development and full characterization of an efficient micellar nanosystem, based on the chemical conjugation between the amphiphilic copolymer Pluronic® L64 and the cationic polymer polyethyleneimine (PEI), to deliver the therapeutic miRNA-145 into OS cells leading to inhibition of cell proliferation and migration, and ultimately inducing cell death, crafting a novel anticancer therapeutic approach to OS.

MiR-564 is down-regulated in osteosarcoma and inhibits the proliferation of osteosarcoma cells via targeting Akt

Aberrant expression of miRNAs has been observed in a variety of human cancers. In this study, we reported that miR-564 was down-regulated in human osteosarcoma (OS) cell lines and patients. Overexpression of miR-564 in OS cells suppressed the cell proliferation and induced cell apoptosis. Mechanistically, we identified Akt as a direct target of miR-564. Highly expressed miR-564 decreased the expression of Akt at both mRNA and protein level and consequently, inhibited the essential role of Akt in the glycolysis of OS cells. Notably, restoring the expression of Akt in miR-564 overexpressing cells recovered the glucose metabolism and cell growth. These results suggested that miR-564 inhibited the glycolysis and cell proliferation through directly targeting Akt, which highlighted the potential application of miR-564-Akt axis in the treatment of osteosarcoma.

Chondromodulin‑I suppresses tumorigenesis of human osteosarcoma cells

Osteosarcoma is the most common type of bone cancer, and accounts for ~3% of cancers that occurring in children. Chondromodulin‑I (ChM-I) is a 25 kDa glycoprotein that is expressed mainly in cartilage. ChM-I demonstrates anti‑angiogenic activity and has been suggested to inhibit endothelial cells from invading cartilage, and then has been shown to be an inhibitor of tumorigenesis. However, it remains unclear if ChM‑I has any direct anti‑tumorigenesis role on osteosarcoma. Therefore, the present study aimed to identify whether ChM‑I has any direct inhibit effect on human osteosarcoma cells. A bromodeoxyuridine incorporation assay was performed on the Saos‑2 human osteosarcoma cell line treated with or without recombinant human ChM‑I, to evaluate its impact on DNA synthesis. An adenovirus carrier for the expression of ChM‑I was constructed and transfected into tumor cells in vitro to evaluate the effect of ChM‑I on tumor cells. Additionally, ChM‑I was knocked down by using small interfering RNA to downregulate the expression of ChM‑I. Cell invasion, migration and cell‑colony formation assays, and xenograft tumor experiments were performed to evaluate the effects of ChM‑I on tumor cells in vitro and in vivo. The results demonstrated that ChM‑I could suppress DNA synthesis of human osteosarcoma cells, and it also exerted an inhibitory effect on the proliferation and colony formation abilities of human osteosarcoma cells. In addition, ChM‑I inhibited cell invasion and migration in vitro and suppressed osteosarcoma cell growth significantly in vivo. In conclusion, ChM‑I directly suppressed the proliferation and growth of osteosarcoma cells in an anchorage‑independent manner, and may therefore be a promising drug for the treatment of osteosarcoma.

Cardiomyocyte apoptosis vs autophagy with prolonged doxorubicin treatment: comparison with osteosarcoma cells

Objective

Doxorubicin (Dox) is a frontline chemotherapeutic against osteosarcoma (OS) that is plagued by side effects, particularly in the heart. The specific objective of this article is to investigate whether low-dose Dox treatment had pro-autophagic effects in cardiomyocytes as well as osteosarcoma cells.

Methods

This study characterises apoptotic (Bax) and autophagic (Beclin-1) biomarker levels in human OS and cardiomyocyte cell lines as well as in various tissues when mice are exposed to low (1 mg/kg, thrice weekly) and high (3 mg/kg thrice weekly) dose Dox for a month.

Key findings

There was a decrease in Bax and increase in Beclin-1 in cardiac tissue in the high-dose group. Dox decreased Beclin-1 in the skin and liver, with no clear indication in the stomach, small intestine and testis. At low Dox doses of 10 and 100 nm in cardiomyocytes and OS cells, there is a pro-apoptotic effect, with a quicker response in the 100-nm condition, and a slower but steady increase of a pro-apoptotic response at the lower 10-nm dose. However, electron microscopy images revealed changes to human OS cells that resembled autophagy. Human prostate, breast and colorectal cells treated with 10-nm Dox showed ∼ 40% reduction in cell viability after 24 h.

Conclusion

In culture, cells of both cardiomyocytes and OS revealed a predominant pro-apoptotic response at the expense of autophagy, although both seemed to be occurring in vivo.

Novel approaches for treating musculoskeletal diseases: molecular orthopedics and systems medicine

Molecular medicine uses knowledge about cell structure and function for disease, diagnostics, stage characterisation and treatment. The advent of genomic technologies is considerably leading to developments in the field of molecular medicine. The accumulation of detailed information about gene expression, epigenetic variability, protein transcription and functional modulation is contributing to a new era in medicine. Rapid and early diagnostic procedures, molecular characterisation of degenerative and proliferative diseases and personalized therapies are predicted to lead to advancements in health prevention and treatment of disease. Diagnostic tools and therapies based on local and /or general modulation of cellular processes for traumatic or degenerative musculoskeletal conditions are becoming available. A logical consequence of the information derived from extensive data gathering, systems biology and systemic medicine has lead to significant improvements in understanding biological structure and function in a simultaneous bottom top and integrative, holistic manner. The description of disease mechanism at an intimate, subcellular level has a dual benefit. A thorough understanding of the crosstalk involved in molecular pathways both in the normal and the diseased state are expanding scientific knowledge and simultaneously are enabling design cell-targeted and individualized therapies. This paper presents a brief overview of current molecular based treatments available to the orthopedic surgeon and introduces the concept of systemic medicine from the perspective of musculoskeletal pathology.

Lentivirus-mediated RNAi knockdown of prostate-specific membrane antigen suppresses growth, reduces migration ability and the invasiveness of prostate cancer cells

Prostate-specific membrane antigen is a type II membrane protein with folate hydrolase activity produced by prostatic epithelium. It has been demonstrated that prostate-specific membrane antigen over-expression may be correlated with prostate cancer, particularly in advanced cancer. The aim of the current study was to explore the possibility of prostate-specific membrane antigen as a therapeutic target for the treatment of prostate cancer. To address this problem, lentivirus-mediated small interfering RNA was employed to reduce endogenous prostate-specific membrane antigen expression in prostate cancer cell lines—LNCaP and DU-145. Then, the tumorigenesis, migration ability and invasiveness of prostate-specific membrane antigen-reduced prostate cancer cell lines were also examined. The prostate-specific membrane antigen expression in LNCaP and DU-145 cells was persistently and markedly reduced by lentivirus-mediated RNA interference. Down-regulation of prostate-specific membrane antigen expression significantly suppressed the growth rates of LNCaP and DU-145 cells. Moreover, the specific down-regulation arrested cells in G0/G1 phase of cell cycle. Furthermore, we also observed that the silence of prostate-specific membrane antigen could decrease the migration ability and the invasiveness of LNCaP and DU-145 cells. Our investigation demonstrated that lentivirus-mediated RNA interference silencing targeting prostate-specific membrane antigen might reduce the proliferation, and induce potent antitumor activity of LNCaP and DU-145 cells. Prostate-specific membrane antigen has considerable potential as a new therapeutic target for the treatment of prostate cancer.

Sensitization of osteosarcoma cell line SaOS-2 to chemotherapy by downregulating survivin

BACKGROUND AND AIMS

Osteosarcoma is the most frequent malignant bone tumor with a peak incidence in the second and third decades of life. Survivin, a member of the IAP family of proteins, is overexpressed in osteosarcomas and plays an important role in protecting cells from apoptosis. Here we investigated the anti-cancer effects of downregulating survivin by shRNA vector pSUPER-sh in combination with chemotherapeutic drugs on human osteosarcoma cells.

METHODS

Expression of survivin was detected by Western blot. The effects of pSUPER-sh and chemotherapeutic drugs on osteosarcoma cell lines Saos-2 and U2OS by cell viability assay and its underlying mechanisms were analyzed by flow cytometry and caspase-3 activity assay.

RESULTS

Downregulated survivin could significantly induce apoptosis of osteosarcoma cell lines Saos-2 and U2OS. The effect probably resulted from downregulation of survivin induced by pSUPER-sh. Importantly, we found that the downregulation of survivin by pSUPER-sh could enhance the anticancer effects of chemotherapies such as etoposide, cisplatin and doxorubicin through decreasing mitochondrial membrane potentials and increasing caspase-3 activity.

CONCLUSIONS

Downregulated survivin by pSUPER-sh could markedly induce apoptosis of osteosarcoma cells lines and pSUPER-sh may be a promising adjuvant in osteosarcoma chemotherapy.

Expression of Beclin1 in osteosarcoma and the effects of down-regulation of autophagy on the chemotherapeutic sensitivity

To explore the expression of Beclin1 in osteosarcoma and investigate the effects of down-regulation of autophagy on the chemotherapeutic sensitivity to cisplatin (DDP), the expression of Beclin1 in 28 specimens of osteosarcoma (group A) and 19 specimens of normal bone tissues (group B) were immunohistochemically detected. The expression of Beclin1 mRNA in MG63 cells treated with different concentrations of DDP was examined with RT-PCR. After down-regulation of autophagy in MG63 cells by an autophagy inhibitor, 3-methyladenine (3-MA), the cell proliferation inhibition rate of MG63 cells treated with DDP was evaluated by using the MTT assay. The positive rates of Beclin1 were 67.85% in group A and 94.73% in group B. Its expression was lower in osteosarcoma than in normal bone tissues, with a significant difference found between them (P<0.05). RT-PCR showed that the expression of Beclin1 mRNA in the cells treated with high-dose DDP were higher than that in the non-treated cells, and no significant difference in the expression of Beclin1 mRNA was found between the cells treated with low-dose DDP and the non-treated cells. There was a positive correlation between the level of Beclin1 mRNA expression and the concentration of DDP. MTT assay showed that the proliferation inhibition rates of the cell treated with 3-MA and DDP combined were substantially increased when compared with those treated with DDP alone (P<0.01). This study demonstrated that autophagy may be implicated in the carcinogenesis of osteosarcoma, and DDP may induce autophagy in the MG63 cells. It also suggests that the down-regulated autophagy could increase chemotherapeutic sensitivity of DDP to osteosarcoma.

Lentivirus-mediated RNAi knockdown of insulin-like growth factor-1 receptor inhibits growth, reduces invasion, and enhances radiosensitivity in human osteosarcoma cells

The type 1 insulin-like growth factor receptor (IGF-1R) is essential for tumorigenicity, tumor proliferation, and protection from apoptosis. IGF-1R overexpression has been found in many human cancers including osteosarcoma. To explore its possibility as a therapeutic target for the treatment of osteosarcoma, lentivirus-mediated siRNA was employed to downregulate endogenous IGF-1R expression to study the function of IGF-1R in tumorigenesis and radioresistance of osteosarcoma cells. The IGF-1R expression was persistently and markedly reduced by lentivirus-mediated RNAi. Downregulation of IGF-1R expression in osteosarcoma cells significantly suppressed their growth rates in vitro and reduced the potential of tumorigenicity in vivo. Moreover, the specific downregulation arrested cells in G(0)/G(1) phase of cell cycle and also induced apoptosis which correlated with the activation of Caspase-3. Furthermore, we also observed that suppression of IGF-1R could reduce the invasiveness of osteosarcoma cells and enhance their radiosensitivity. Our study suggested that lentivirus-mediated RNAi silencing targeting IGF-1R could induce potent antitumor activity and radiosensitizing activity in human osteosarcomas.