METTL3 Promotes Osteosarcoma Metastasis via an m6A-dependent Epigenetic Activity of CBX4

BACKGROUND

Osteosarcoma cells are prone to metastasis, and the mechanism of N6-methyladenosine (m6A) methylation modification in this process is still unclear. Methylation modification of m6A plays an important role in the development of osteosarcoma, which is mainly due to abnormal expression of enzymes related to methylation modification of m6A, which in turn leads to changes in the methylation level of downstream target genes messenger RNA (mRNA) leading to tumor development.

METHODS

We analyzed the expression levels of m6A methylation modification-related enzyme genes in GSE12865 whole-genome sequencing data. And we used shRNA (short hairpin RNA) lentiviral interference to interfere with METTL3 (Methyltransferase 3) expression in osteosarcoma cells. We studied the cytological function of METTL3 by Cell Counting Kit-8 (CCK8), flow cytometry, migration and other experiments, and the molecular mechanism of METTL3 by RIP (RNA binding protein immunoprecipitation), Western blot and other experiments.

RESULTS

We found that METTL3 is abnormally highly expressed in osteosarcoma and interferes with METTL3 expression in osteosarcoma cells to inhibit metastasis, proliferation, and apoptosis of osteosarcoma cells. We subsequently found that METTL3 binds to the mRNA of CBX4 (chromobox homolog 4), a very important regulatory protein in osteosarcoma metastasis, and METTL3 regulates the mRNA and protein expression of CBX4. Further studies revealed that METTL3 inhibited metastasis of osteosarcoma cells by regulating CBX4. METTL3 has been found to be involved in osteosarcoma cells metastasis by CBX4 affecting the protein expression of matrix metalloproteinase 2 (MMP2), MMP9, E-Cadherin and N-Cadherin associated with osteosarcoma cells metastasis.

CONCLUSIONS

These results suggest that the combined action of METTL3 and CBX4 plays an important role in the regulation of metastasis of osteosarcoma, and therefore, the METTL3-CBX4 axis pathway may be a new potential therapeutic target for osteosarcoma.

Massage manipulation and progression of osteosarcoma, does it really correlate: a combination of prospective and retrospective cohort study

In Indonesia, the challenge of osteosarcoma progression is further worsened by patients' dependence on traditional massage therapy, low socio-economy, and educational status. This study aims to analyze the differences in the characteristics, laboratory findings, surgery techniques, degree of histopathological necrosis, and metastasis between osteosarcoma patients with and without prior massage manipulation therapy. This research is an analytical observational study with a prospective and retrospective cohort design. Patients were treated and followed for one year to evaluate the occurrence of metastasis. Prospective data was collected through interviews, and secondary data was collected from the patient's medical record. Of 84 subjects analyzed, 69% had a history of massage. There was an increase in LDH and ALP in patients with massage manipulation (p = 0.026). The median time to metastasis from baseline in the massage group (4 months) was statistically significant compared to the non-manipulation group (12 months) (p < 0.0001). This research found that massage therapy significantly increases LDH and ALP levels, making amputations more likely to be performed and a higher risk of metastasis that lowered the survival rate. The onset of metastasis was three times faster in patients with prior massage therapy. Therefore, we strongly recommend against massage manipulation therapy in osteosarcoma patients.

CT features of osteosarcoma lung metastasis: a retrospective study of 127 patients

Objective: Osteosarcoma lung metastases have a wide variety of CT presentations, representing a challenge for radiologists. Knowledge of atypical CT patterns of lung metastasis is important to differentiate it from benign lung disease and synchronous lung cancer, as well as to determine the extent of primary disease. The objective of this study was to analyze CT features of osteosarcoma lung metastasis before and during chemotherapy. Methods: Two radiologists independently reviewed chest CT images of 127 patients with histopathologically confirmed osteosarcoma treated between May 10, 2012 and November 13, 2020. The images were divided into two groups for analysis: images obtained before chemotherapy and images obtained during chemotherapy (initial CT examination). Results: Seventy-five patients were diagnosed with synchronous or metachronous lung metastases. The most common CT findings were nodules (in 95% of the patients), distributed bilaterally (in 86%), with no predominance regarding craniocaudal distribution (in 71%). Calcification was observed in 47%. Less common findings included intravascular lesions (in 16%), cavitation (in 7%), and the halo sign (in 5%). The primary tumor size was significantly greater (i.e., > 10 cm) in patients with lung metastasis. Conclusions: On CT scans, osteosarcoma lung metastases typically appear as bilateral solid nodules. However, they can have atypical presentations, with calcification being the most common. Knowledge of the typical and atypical CT features of osteosarcoma lung metastasis could play a key role in improving image interpretation in these cases.

[CircRNA circTNPO1 promotes the proliferation and metastasis of osteosarcoma by sponging miR-338-3p]

Objective: To explore the effects of circTNPO1 on the proliferation and metastasis of osteosarcoma (OS) by sponging miR-338-3p. Methods: The expression of circTNPO1 on osteoblasts and multiple OS cell lines were detected by qRT-PCR. CircTNPO1 stable knockdown 143B cell line was constructed by sh-circTNPO1. Cell count kit 8 (CCK-8) assay and wound healing assay were applied to evaluate the proliferation and metastasis of this cell. Luciferase reporter assay was used to explore the binding between circTNPO1 and miR-338-3p. In xenograft tumor model, miR-338-3p inhibitor or its control was injected into the circTNPO1 knockdown tumors. The weight and size of the tumors were evaluated and Ki-67 expression was detected by immunohistochemistry. Results: The RNA expression of circTNPO1 in OS cell lines U2OS, HOS, MG63, 143B, ZOS and ZOSM were 2.73±0.27, 3.18±0.54, 4.33±0.52, 5.75±0.65, 4.50±0.49 and 3.96±0.35, respectively, higher than 1.00±0.09 in hFOB1.19 (P<0.001). CCK-8 assay revealed that after 48 h and 72 h, the absorbance of sh-circTNPO1 #1 was 0.81±0.05 and 1.09±0.06, while sh-circTNPO1 #2 143B cells was 0.84±0.04 and 1.2±0.04, which were sharply reduced compared with the control (1.00±0.06 and 1.49±0.06, P<0.001); after 48 h and 72 h, the absorbance of 143B cells transfected with circTNPO1 #1 and miR-338-3p (0.92±0.06 and 1.32±0.07) were higher than those of cells transfected with sh-circTNPO1 cells and miR NC (0.92±0.06 and 1.32±0.07, P<0.050). Wound healing assay demonstrated that the 24 hour-migration rates of sh-circTNPO1 #1 and sh-circTNPO1 #2 cells were (24.43±2.15)% and (39.70±4.20)% respectively, which were significantly lower than that of the control [(56.51±3.27)%, P<0.010]; the migration rates of sh-circTNPO1 #1+ miR NC and sh-circTNPO1 #1+ miR-338-3p inhibitor were (26.70±2.21)% and (46.10±5.71)%, with a significant difference (P<0.005). In xenograft tumor model, the weight and size of tumors in control, sh-circTNPO1 #1+ miR NC and sh-circTNPO1 #1+ miR-338-3p inhibitor mice were (458.80±158.10) mg, (262.50±82.09) mg, (395.40±137.60) mg and (593.00±228.40) mm(2,) (203.30±144.20) mm(2,) (488.60±208.60) mm(2,) respectively. Compared with control, sh-circTNPO1 tumors were significantly smaller (P<0.01). Injection with miR-338-3p inhibitor significantly reversed both the weight and size of tumors (P<0.05). Conclusion: CircTNPO1 promotes the proliferation and metastasis of OS by sponging miR-338-3p, which could be a new target for OS treatments.

[Synchronic multicentric osteosarcoma. A case in a 10 year old boy and review of the literature]

The osteosarcoma is a malignant neoplasm originating in bone-producing cells whose usual presentation is predominantly monostotic in long bones. The polyostotic expression is rare, variable and controversial, predominantly high-grade cellular lesions in children; low-grade lesions that affect long bones in adults and others that show a dominant lesion in long bones from which metastases arise. We present the case of a ten-year-old patient with painful tumors in metaphasis and diaphysis of the femur, tibia, fibula, clavicle, humerus, as well as in pelvis, vertebrae and base of the skull of synchronous appearance with blindness. Diagnosis was made through X-ray images, CT scan, magnetic resonance imaging (MRI), and incisional biopsy of the femur. Evidenced of absence of neoplastic manifestation in lung imaging, at the time of pathological diagnosis. Histological findings revealed a high-grade osteosarcoma.

Potential Anti-Metastatic Role of the Novel miR-CT3 in Tumor Angiogenesis and Osteosarcoma Invasion

Osteosarcoma (OS) is the most common primary bone tumor mainly occurring in young adults and derived from primitive bone-forming mesenchyme. OS develops in an intricate tumor microenvironment (TME) where cellular function regulated by microRNAs (miRNAs) may affect communication between OS cells and the surrounding TME. Therefore, miRNAs are considered potential therapeutic targets in cancer and one of the goals of research is to accurately define a specific signature of a miRNAs, which could reflect the phenotype of a particular tumor, such as OS. Through NGS approach, we previously found a specific molecular profile of miRNAs in OS and discovered 8 novel miRNAs. Among these, we deepen our knowledge on the fifth candidate renamed now miR-CT3. MiR-CT3 expression was low in OS cells when compared with human primary osteoblasts and healthy bone. Through TargetScan, VEGF-A was predicted as a potential biological target of miR-CT3 and luciferase assay confirmed it. We showed that enforced expression of miR-CT3 in two OS cell lines, SAOS-2 and MG-63, reduced expression of VEGF-A mRNA and protein, inhibiting tumor angiogenesis. Enforced expression of miR-CT3 also reduced OS cell migration and invasion as confirmed by soft agar colony formation assay. Interestingly, we found that miR-CT3 behaves inducing the activation of p38 MAP kinase pathway and modulating the epithelial-mesenchymal transition (EMT) proteins, in particular reducing Vimentin expression. Overall, our study highlights the novel role of miR-CT3 in regulating tumor angiogenesis and progression in OS cells, linking also to the modulation of EMT proteins.

Osteocytes and Cancer

PURPOSE OF REVIEW

While the function of osteocytes under physiologic conditions is well defined, their role and involvement in cancer disease remains relatively unexplored, especially in a context of non-bone metastatic cancer. This review will focus on describing the more advanced knowledge regarding the interactions between osteocytes and cancer.

RECENT FINDINGS

We will discuss the involvement of osteocytes in the onset and progression of osteosarcoma, with the common bone cancers, as well as the interaction that is established between osteocytes and multiple myeloma. Mechanisms responsible for cancer dissemination to bone, as frequently occur with advanced breast and prostate cancers, will be reviewed. While a role for osteocytes in the stimulation and proliferation of cancer cells has been reported, protective effects of osteocytes against bone colonization have been described as well, thus increasing ambiguity regarding the role of osteocytes in cancer progression and dissemination. Lastly, supporting the idea that skeletal defects can occur also in the absence of direct cancer dissemination or osteolytic lesions directly adjacent to the bone, our recent findings will be presented showing that in the absence of bone metastases, the bone microenvironment and, particularly, osteocytes, can manifest a clear and dramatic response to the distant, non-metastatic tumor. Our observations support new studies to clarify whether treatments designed to preserve the osteocytes can be combined with traditional anticancer therapies, even when bone is not directly affected by tumor growth.

LncRNA MATN1-AS1 for Prediction of Prognosis in Osteosarcoma Patients and Its Cellular Function

Long non-coding RNAs show essential roles in various cancer processes. This study aimed at the expression features, prognosis significance, and biological effect of lnc MATN1-AS1 in osteosarcoma (OS). Five kinds of cell lines and 117 pairs of tissues were analyzed by qRT-PCR for quantification of lnc MATN1-AS1 and miR-1299 level. Clinical data were analyzed using Chi-Square Tests to show the association with lnc MATN1-AS1 level. Kaplan-Meier analysis and Cox regression were used to judge the prognostic value. Cell counting kit-8 and Transwell assay were conducted, respectively, to analyze the effect of lnc MATN1-AS1 on cell proliferation and metastasis. The target miRNA was predicted. lnc MATN1-AS1 level was significantly elevated in OS cells and tissues and related to Enneking staging, lung metastasis, and histologic type. Patients with high lnc MATN1-AS1 level showed a shorter overall survival and recurrence-free survival. Lnc MATN1-AS1 knockdown inhibited OS cell proliferation, migration, and invasion by sponging miR-1299. Lnc MATN1-AS1 has oncogenic features and prognostic significance in OS and is a novel therapeutic strategy for OS.

A new antisarcoma strategy: multisubtype heat shock protein/peptide immunotherapy combined with PD-L1 immunological checkpoint inhibitors

Osteosarcoma, a common malignant tumor in orthopedics, often has a very poor prognosis after lung metastasis. Immunotherapy has not achieved much progress in the treatment because of the characteristics of solid tumors and immune environment of osteosarcoma. The tumor environment is rather essential for sarcoma treatment. Our previous study demonstrated that heat shock proteins could be used as antitumor vaccines by carrying tumor antigen peptides, and we hypothesize that an anti-osteosarcoma effect may be increased with an immune check point inhibitor (PD-L1 inhibitor) as a combination treatment strategy. The present study prepared a multisubtype mixed heat shock protein osteosarcoma vaccine (mHSP/peptide vaccine) and concluded that the mHSP/peptide vaccine was more effective than a single subtype heat shock protein, like Grp94. Therefore, we used the mHSP/peptide vaccine in combination with a PD-L1 inhibitor to treat osteosarcoma, and the deterioration of osteosarcoma was effectively hampered. The mechanism of combined therapy was investigated, and AKT expression participates with sarcoma lung metastasis. This study proposed an antisarcoma strategy via stimulation of the immune system as a further alternative approach for sarcoma treatment and elucidated the mechanism of combined therapy.

m6A regulators are associated with osteosarcoma metastasis and have prognostic significance: A study based on public databases

BACKGROUND

Osteosarcoma represents the most common malignant bone tumor with high metastatic potential and inferior prognosis. RNA methylation (N6-methyladenosine [m6A]) is a prevalent RNA modification that epigenetically influences numerous biological processes including tumorigenesis. This study aims to determine that m6A regulators are significant biomarkers for osteosarcoma, and establish a prognostic model to predict the survival of patients.

METHODS

In this study, we comprehensively analyzed the underlying associations between m6A regulators' mRNA expressions and metastasis as well as prognosis of osteosarcoma patients in the Cancer Genome Atlas. Multivariate Cox-regression analysis was used to screen regulators that were significantly associated with overall survival of osteosarcoma patients. Least absolute shrinkage and selection operator (LASSO) Cox-regression analysis was used for constructing m6A regulator-based osteosarcoma prognostic signature.

RESULTS

Some of the regulators exhibited aberrant mRNA levels between osteosarcoma samples with and without metastasis. Multivariate Cox-regression analysis identified several regulators with potential prognostic significance. A risk score formula consisted of methyltransferase-like 3, YTH domains of Homo sapiens, and fat mass and obesity-associated protein was obtained through which patients could be prognostically stratified independently of potential confounding factors. The signature was also significantly associated with the metastatic potential of osteosarcoma. All the analyses could be well reproduced in another independent osteosarcoma cohort from the Gene Expression Omnibus.

CONCLUSIONS

In conclusion, this study first revealed potential roles of m6A regulators in osteosarcoma metastasis and prognosis, which should be helpful for its clinical decision-making.

Inhibition of the Notch signaling pathway attenuates progression of cell motility, metastasis, and epithelial-to-mesenchymal transition-like phenomena induced by low concentrations of cisplatin in osteosarcoma

Although advances in osteosarcoma treatment have been made in recent decades, the survival rate for patients suffering from metastatic disease, especially lung metastasis, remains disappointing. Previous studies have confirmed that epithelial-to-mesenchymal transition (EMT) is associated with tumor metastasis, and several studies have suggested that osteosarcoma cells also exhibit EMT-like characteristics. In addition, Notch signaling is known to be related to the development and progression of human malignancies, including osteosarcoma. However, whether chemotherapy affects the EMT-like events and whether these events are medicated by Notch signaling remain to be elucidated. To address these issues, in the current work, osteosarcoma 143B cells were exposed to sublethal concentrations of the first-line chemotherapeutic agent cisplatin (DDP), which promoted cell migration, in vitro invasion, and in vivo lung metastasis. Furthermore, low concentrations of DDP upregulated mesenchymal phenotype-related genes and proteins and promoted EMT-like properties in osteosarcoma cells. In addition, low concentrations of DDP could activate the Notch receptor and its target genes. Finally, combined treatment of DDP with the Notch signaling pathway inhibitor DAPT, which can effectively downregulate mesenchymal phenotype-related genes and proteins, inhibited cell migration and invasion in vitro, and it decreased pulmonary metastatic nodules in vivo. The results of the current study supported the idea that low concentrations of DDP could induce EMT-like characteristics in osteosarcoma cells and could promote cell mobility in vitro, as well as pulmonary metastasis in vivo. Importantly, however, these biological processes are mediated by the Notch signaling pathway. Blocking the Notch signaling pathway can effectively attenuate the osteosarcoma EMT-like phenotype and its associated migration, invasion, and metastasis.

A Novel Orthotopic Mouse Model of Lung Metastasis Using Fluorescent Patient-derived Osteosarcoma Cells

BACKGROUND

A mouse model of metastatic osteosarcoma is imperative to identify effective agents for metastatic osteosarcoma, which is a recalcitrant disease. In the present study, we established osteosarcoma patient-derived cells (OS-PDCs) and transfected them with green fluorescent protein (GFP).

MATERIALS AND METHODS

The OS-PDCs were transfected with GFP-lentivirus. GFP-expressing OS-PDCs (2.0×105) were then injected into the tibia of nude mice to establish the patient-derived orthotopic cell (PDOC) model (n=3). Six weeks after injection, the primary tumor and each organ were resected and imaged.

RESULTS

Primary orthotopic tumors were established in two out of three mice. The GFP-expressing OS-PDCs in the PDOC model were visualized. Multiple GFP-expressing lung metastases were detected in one of the two mice with primary tumor.

CONCLUSION

The present study proves the concept that a GFP-expressing PDOC model can mimic clinical lung-metastatic osteosarcoma. This model can serve as a paradigm to screen for effective drugs for osteosarcoma lung metastasis.

Radiation Disrupts the Protective Function of the Spinal Meninges in a Mouse Model of Tumor-induced Spinal Cord Compression

BACKGROUND

Recent advances in multidisciplinary treatments for various cancers have extended the survival period of patients with spinal metastases. Radiotherapy has been widely used to treat spinal metastases; nevertheless, long-term survivors sometimes undergo more surgical intervention after radiotherapy because of local tumor relapse. Generally, intradural invasion of a spinal tumor seldom occurs because the dura mater serves as a tissue barrier against tumor infiltration. However, after radiation exposure, some spinal tumors invade the dura mater, resulting in leptomeningeal dissemination, intraoperative dural injury, or postoperative local recurrence. The mechanisms of how radiation might affect the dura have not been well-studied.

QUESTIONS/PURPOSES

To investigate how radiation affects the spinal meninges, we asked: (1) What is the effect of irradiation on the meningeal barrier's ability to protect against carcinoma infiltration? (2) What is the effect of irradiation on the meningeal barrier's ability to protect against sarcoma infiltration? (3) What is the effect of irradiation on dural microstructure observed by scanning electron microscopy (SEM)? (4) What is the effect of irradiation on dural microstructure observed by transmission electron microscopy (TEM)?

METHODS

Eighty-four 10-week-old female ddY mice were randomly divided into eight groups: mouse mammary tumor (MMT) implantation 6 weeks after 0-Gy irradiation (nonirradiation) (n = 11), MMT implantation 6 weeks after 20-Gy irradiation (n = 10), MMT implantation 12 weeks after nonirradiation (n = 10), MMT implantation 12 weeks after 20-Gy irradiation (n = 11), mouse osteosarcoma (LM8) implantation 6 weeks after nonirradiation (n = 11), LM8 implantation 6 weeks after 20-Gy irradiation (n = 11), LM8 implantation 12 weeks after nonirradiation (n = 10), and LM8 implantation 12 weeks after 20-Gy irradiation (n = 10); female mice were used for a mammary tumor metastasis model and ddY mice, a closed-colony mice with genetic diversity, were selected to represent interhuman diversity. Mice in each group underwent surgery to generate a tumor-induced spinal cord compression model at either 6 weeks or 12 weeks after irradiation to assess changes in the meningeal barrier's ability to protect against tumor infiltration. During surgery, the mice were implanted with MMT (representative of a carcinoma) or LM8 tumor. When the mice became paraplegic because of spinal cord compression by the growing implanted tumor, they were euthanized and evaluated histologically. Four mice died from anesthesia and 10 mice per group were euthanized (MMT-implanted groups: MMT implantation occurred 6 weeks after nonirradiation [n = 10], 6 weeks after irradiation [n = 10], 12 weeks after nonirradiation [n = 10], and 12 weeks after irradiation [n = 10]; LM8-implanted groups: LM8 implantation performed 6 weeks after nonirradiation [n = 10], 6 weeks after irradiation [n = 10], 12 weeks after nonirradiation [n = 10], and 12 weeks after irradiation [n = 10]); 80 mice were evaluated. The spines of the euthanized mice were harvested; hematoxylin and eosin staining and Masson's trichrome staining slides were prepared for histologic assessment of each specimen. In the histologic assessment, intradural invasion of the implanted tumor was graded in each group by three observers blinded to the type of tumor, presence of irradiation, and the timing of the surgery. Grade 0 was defined as no intradural invasion with intact dura mater, Grade 1 was defined as intradural invasion with linear dural continuity, and Grade 2 was defined as intradural invasion with disruption of the dural continuity. Additionally, we euthanized 12 mice for a microstructural analysis of dura mater changes by two observers blinded to the presence of irradiation. Six mice (three mice in the 12 weeks after nonirradiation group and three mice in the 12 weeks after 20-Gy irradiation group) were quantitatively analyzed for defects on the dural surface with SEM. The other six mice (three mice in the 12 weeks after nonirradiation group and three mice in the 12 weeks after 20-Gy irradiation group) were analyzed for layer structure of collagen fibers constituting dura mater by TEM. In the SEM assessment, the number and size of defects on the dural surface on images (200 μm × 300 μm) at low magnification (× 2680) were evaluated. A total of 12 images (two per mouse) were evaluated for this assessment. The days from surgery to paraplegia were compared between each of the tumor groups using the Kruskal-Wallis test. The scores of intradural tumor invasion grades and the number of defects on dural surface per SEM image were compared between irradiation group and nonirradiation group using the Mann-Whitney U test. Interobserver reliabilities of assessing intradural tumor invasion grades and the number of dural defects on the dural surface were analyzed using Fleiss'κ coefficient. P values < 0.05 were considered statistically significant.

RESULTS

There was no difference in the median (range) time to paraplegia among the MMT implantation 6 weeks after nonirradiation group, the 6 weeks after irradiation group, the 12 weeks after nonirradiation group, and the 12 weeks after irradiation group (16 days [14 to 17] versus 14 days [12 to 18] versus 16 days [14 to 17] versus 14 days [12 to 15]; χ2 = 4.7; p = 0.19). There was also no difference in the intradural invasion score between the MMT implantation 6 weeks after irradiation group and the 6 weeks after nonirradiation group (8 of 10 Grade 0 and 2 of 10 Grade 1 versus 10 of 10 Grade 0; p = 0.17). On the other hand, there was a higher intradural invasion score in the MMT implantation 12 weeks after irradiation group than the 12 weeks after nonirradiation group (5 of 10 Grade 0, 3 of 10 Grade 1 and 2 of 10 Grade 2 versus 10 of 10 Grade 0; p = 0.02). Interobserver reliability of assessing intradural tumor invasion grades in the MMT-implanted group was 0.94. There was no difference in the median (range) time to paraplegia among in the LM8 implantation 6 weeks after nonirradiation group, the 6 weeks after irradiation group, the 12 weeks after nonirradiation group, and the 12 weeks after irradiation group (12 days [9 to 13] versus 10 days [8 to 13] versus 11 days [8 to 13] versus 9 days [6 to 12]; χ2 = 2.4; p = 0.50). There was also no difference in the intradural invasion score between the LM8 implantation 6 weeks after irradiation group and the 6 weeks after nonirradiation group (7 of 10 Grade 0, 1 of 10 Grade 1 and 2 of 10 Grade 2 versus 8 of 10 Grade 0 and 2 of 10 Grade 1; p = 0.51), whereas there was a higher intradural invasion score in the LM8 implantation 12 weeks after irradiation group than the 12 weeks after nonirradiation group (3 of 10 Grade 0, 3 of 10 Grade 1 and 4 of 10 Grade 2 versus 8 of 10 Grade 0 and 2 of 10 Grade 1; p = 0.04). Interobserver reliability of assessing intradural tumor invasion grades in the LM8-implanted group was 0.93. In the microstructural analysis of the dura mater using SEM, irradiated mice had small defects on the dural surface at low magnification and degeneration of collagen fibers at high magnification. The median (range) number of defects on the dural surface per image in the irradiated mice was larger than that of nonirradiated mice (2 [1 to 3] versus 0; difference of medians, 2/image; p = 0.002) and the median size of defects was 60 μm (30 to 80). Interobserver reliability of assessing number of defects on the dural surface was 1.00. TEM revealed that nonirradiated mice demonstrated well-organized, multilayer structures, while irradiated mice demonstrated irregularly layered structures at low magnification. At high magnification, well-ordered cross-sections of collagen fibers were observed in the nonirradiated mice. However, disordered alignment of collagen fibers was observed in irradiated mice.

CONCLUSION

Intradural tumor invasion and disruptions of the dural microstructure were observed in the meninges of mice after irradiation, indicating radiation-induced disruption of the meningeal barrier.

CLINICAL RELEVANCE

We conclude that in this form of delivery, radiation is associated with disruption of the dural meningeal barrier, indicating a need to consider methods to avoid or limit Postradiation tumor relapse and spinal cord compression when treating spinal metastases so that patients do not experience intradural tumor invasion. Surgeons should be aware of the potential for intradural tumor invasion when they perform post-irradiation spinal surgery to minimize the risks for intraoperative dural injury and spinal cord injury. Further research in patients with irradiated spinal metastases is necessary to confirm that the same findings are observed in humans and to seek irradiation methods that prevent or minimize the disruption of meningeal barrier function.

Risk Factors, Prognostic Factors, and Nomograms for Distant Metastasis in Patients With Newly Diagnosed Osteosarcoma: A Population-Based Study

BACKGROUND

Osteosarcoma is the most common bone cancer, mainly occurring in children and adolescents, among which distant metastasis (DM) still leads to a poor prognosis. Although nomogram has recently been used in tumor areas, there are no studies focused on diagnostic and prognostic evaluation of DM in primary osteosarcoma patients.

METHODS

The data of osteosarcoma patients diagnosed between 2004 and 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate logistic regression analyses were used to identify independent risk factors for DM in osteosarcoma patients, and univariate and multivariate Cox proportional hazards regression analyses were used to determine independent prognostic factors of osteosarcoma patients with DM. We then established two novel nomograms and the results were evaluated by receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA).

RESULT

A total of 1,657 patients with osteosarcoma were included, and 267 patients (16.11%) had DM at the time of diagnosis. The independent risk factors for DM in patients with osteosarcoma include age, grade, T stage, and N stage. The independent prognostic factors for osteosarcoma patients with DM are age, chemotherapy and surgery. The results of ROC curves, calibration, DCA, and Kaplan-Meier (K-M) survival curves in the training, validation, and expanded testing sets, confirmed that two nomograms can precisely predict occurrence and prognosis of DM in osteosarcoma patients.

CONCLUSION

Two nomograms are expected to be effective tools for predicting the risk of DM for osteosarcoma patients and personalized prognosis prediction for patients with DM, which may benefit clinical decision-making.

Patrolling monocytes inhibit osteosarcoma metastasis to the lung

Immune infiltration is associated with osteosarcoma metastasis. However, previous studies have not accounted for the functional diversity of the cells involved in the immune response. We conducted a comprehensive comparative analysis of the tumor-infiltrating immune cells in metastatic and non-metastatic osteosarcoma tissues based on a deconvolution algorithm (CIBERSORT). Twenty-two immune cell subsets were evaluated for their association with the presence or absence of metastasis in osteosarcoma patients. A lack of monocytes was associated with osteosarcoma metastasis; however, the levels of M1 macrophages, M2 macrophages and other immune cell subsets did not differ between the metastatic and non-metastatic groups. Additionally, a higher proportion of monocytes was associated with a better prognosis in osteosarcoma patients. Animal experiments demonstrated that the number of metastatic nodules was higher in mice lacking patrolling monocytes than in control mice. Our data indicated that the cellular composition of the immune infiltrate may subtly differ among osteosarcoma patients, and that patrolling monocytes inhibit osteosarcoma metastasis to the lungs of mice. Thus, the composition of the immune infiltrate and the level of patrolling monocytes may be important determinants of whether metastasis occurs in osteosarcoma patients.

Long Noncoding RNA HAGLROS Promotes Cell Invasion and Metastasis by Sponging miR-152 and Upregulating ROCK1 Expression in Osteosarcoma

BACKGROUND

Long noncoding RNAs (lncRNAs) played a crucial role in a number of biological processes. lncRNA HAGLROS was demonstrated to facilitate cell proliferation and migration in various cancers. However, the functions and molecular mechanisms of HAGLROS in osteosarcoma remained to be elucidated.

METHODS

qRT-PCR assay was used to detect the relative expression of HAGLROS in osteosarcoma tissue samples and cells. CCK-8 and Transwell assays were performed to assess the effects of HAGLROS on OS cells proliferation and invasion. Luciferase reporter assay verified the interaction between ROCK1 and miR-152.

RESULTS

In our study, we found that the expression of HAGLROS increased osteosarcoma samples and cell lines compared with normal tissues and cells. HAGLROS knockdown inhibited certain functions of U2OS and SW1353 cells in vitro. Moreover, HAGLROS depletion inhibited tumor growth and metastasis in vivo. Mechanically, we found that HAGLROS sponged miR-152 to promote ROCK1 expression in U2OS and SW1353 cells.

CONCLUSION

In summary, our study indicated that HAGLROS could promote osteosarcoma progression by sponging miR-152 to promote ROCK1 expression. The results showed HAGLROS/miR-152/ROCK1 axis might act as a novel therapeutic strategy for osteosarcoma.

The inhibition of microRNA-326 by SP1/HDAC1 contributes to proliferation and metastasis of osteosarcoma through promoting SMO expression

Osteosarcoma (OS) is a malignant bone cancer lacking of effective treatment target when the metastasis occurred. This study investigated the implication of MicroRNA-326 in OS proliferation and metastasis to provide the clue for the treatment of metastatic OS. This study knocked down SP1 in MG63 and 143B cells and then performed Microarray assay to find the expression of miRNAs that were influenced by SP1. MTT, EdU, wound-healing and cell invasion assays were performed to evaluated cell proliferation and invasion. OS metastasis to lung was detected in a nude mice model. ChIP assay and DAPA were applied to determine the regulatory effect of SP1 and histone deacetylase 1 (HDAC) complex on miR-326 expression. Human OS tissues showed lowly expressed miR-326 but highly expressed Sp1 and HDAC. Sp1 recruited HDAC1 to miR-326 gene promoter, which caused the histone deacetylation and subsequent transcriptional inhibition of miR-326 gene. miR-326 deficiency induced the stimulation of SMO/Hedgehog pathway and promoted the proliferation and invasion of 143B and MG63 cells as well as the growth and metastasis in nude mice. SP1/HDAC1 caused the transcriptional inhibition of miR-326 gene by promoting histone deacetylation; miR-326 deficiency conversely stimulated SMO/Hedgehog pathway that was responsible for the proliferation and metastasis of OS.

Very late relapse of high-grade osteosarcoma: A case report and review of the literature

RATIONALE

Osteosarcoma is the most common primary malignant bone tumor in children. The prognosis of osteosarcoma has improved with the use of aggressive systemic chemotherapy in addition to surgery. The relapse of osteosarcomas is usually as lung metastasis observed within 2 to 3 years after the initial treatment. A relapse is rarely observed at >10 years.

PATIENT CONCERNS

We report the case of a 51-year-old Japanese man who was treated for high-grade osteosarcoma of the femur at 13 years old. He was referred to our hospital with a suspicion of primary lung cancer based on back pain, respiratory distress, and an abnormal mass on chest radiograph.

DIAGNOSES

Computed tomography-guided biopsy confirmed the lung lesion as a metastatic recurrence of high-grade osteosarcoma without local recurrence.

INTERVENTIONS

Chemotherapy was planned, but the patient's general condition rapidly deteriorated and thus palliative therapy was provided.

OUTCOMES

The patient died 2 months after the initial consultation.

LESSONS

The survival durations of osteosarcoma patients have been prolonged by recent progress in multimodality therapy, and thus clinicians as well as osteosarcoma patients should always keep in mind the possibility of very late relapse.

Exosomes in Bone Sarcomas: Key Players in Metastasis

Bone sarcomas are rare cancers which often present with metastatic disease and are still associated with poor survival rates. Studies in the last decade have identified that exosomes, a type of extracellular vesicle released by cells, play an important role in tumour progression and dissemination. Through the transfer of their cargo (RNAs, proteins, and lipids) across cells, they are involved in cellular cross-talk and can induce changes in cellular behaviour. Exosomes have been shown to be important in metastasis organotropism, induction of angiogenesis and vascular permeability, the education of cells towards a pro-metastatic phenotype or the interaction between stromal and tumour cells. Due to the importance exosomes have in disease progression and the high incidence of metastasis in bone sarcomas, recent studies have evaluated the implications of these extracellular vesicles in bone sarcomas. In this review, we discuss the studies that evaluate the role of exosomes in osteosarcoma, Ewing sarcoma, and preliminary data on chondrosarcoma.

MicroRNAs in Bone Metastasis

PURPOSE OF REVIEW

This review provides an update on the recent literature describing the role of microRNAs (miRNAs) in cancer formation and bone metastasis. We confined our focus on osteosarcoma, breast cancer, prostate cancer, and epithelial-mesenchymal transition.

RECENT FINDINGS

In all areas covered, major discoveries on the role of miRNAs in tumorigenesis and metastasis have been made. Novel signaling networks were identified with miRNAs having a central function. Potential improvements in the diagnosis of malignant diseases and the long-term follow-up might become possible by the use of miRNAs. Furthermore, miRNAs also have disease-modifying properties and might emerge as a new class of therapeutic molecules. MiRNAs are novel and important regulators of multiple cellular and molecular events. Due to their functions, miRNAs might become useful to improve the diagnosis, follow-up and treatment of cancer, and metastases. Thus, miRNAs are molecules of great interest in translational medicine.

Randomized Double-Blind Phase II Study of Regorafenib in Patients With Metastatic Osteosarcoma

PURPOSE

SARC024 is a phase II clinical trial of the multikinase inhibitor regorafenib in specific sarcoma subtypes, including advanced osteosarcoma. We hypothesized that regorafenib would improve progression-free survival (PFS) in patients with sarcoma and report the results of the osteosarcoma cohort.

PATIENTS AND METHODS

This trial enrolled patients with progressive metastatic osteosarcoma with measurable disease by RECIST who had received at least one prior line of therapy. Patients were randomly assigned at a ratio of one to one to regorafenib or placebo. Crossover was allowed at time of disease progression. PFS was the primary end point of the study, which was powered to detect a difference of at least 3 months in median PFS.

RESULTS

Forty-two patients from 12 centers were enrolled between September 2014 and May 2018. Median age was 37 years (range, 18 to 76 years). Patients had received an average of 2.3 prior therapy regimens. Ten patients receiving placebo crossed over to active drug at time of progression. Study enrollment was stopped early, after a data safety monitoring committee review. Median PFS was significantly improved with regorafenib versus placebo: 3.6 months (95% CI, 2.0 to 7.6 months) versus 1.7 months (95% CI, 1.2 to 1.8 months), respectively (hazard ratio, 0.42; 95% CI, 0.21 to 0.85; P = .017). In the context of the crossover design, there was no statistically significant difference in overall survival. Fourteen (64%) of 22 patients initially randomly assigned to regorafenib experienced grade 3 to 4 events attributed to treatment, including one grade 4 colonic perforation.

CONCLUSION

The study met its primary end point, demonstrating activity of regorafenib in patients with progressive metastatic osteosarcoma. No new safety signals were observed. Regorafenib should be considered a treatment option for patients with relapsed metastatic osteosarcoma.

Identification of co-expression modules and pathways correlated with osteosarcoma and its metastasis

BACKGROUND

Osteosarcoma is the most common bone tumor that occurs in children.

METHODS

To identify co-expression modules and pathways correlated with osteosarcoma and its clinical characteristics, we performed weighted gene co-expression network analysis (WGCNA) on RNA-seq data of osteosarcoma with 52 samples. Then we performed pathway enrichment analysis on genes from significant modules.

RESULTS

A total of 5471 genes were included in WGCNA, and 16 modules were identified. Module-trait analysis identified that a module involved in microtubule bundle formation, drug metabolism-cytochrome P450, and IL-17 signaling pathway was negatively correlated with osteosarcoma and positively correlated with metastasis; a module involved in DNA replication was positively correlated with osteosarcoma; a module involved in cell junction was positively correlated with metastasis; and a module involved in heparin binding negatively correlated with osteosarcoma. Moreover, expression levels in four of the top ten differentially expressed genes were validated in another independent dataset.

CONCLUSIONS

Our analysis might provide insight for molecular mechanisms of osteosarcoma.

A case report of primary osteosarcoma originating from kidney

RATIONALE

Primary osteosarcoma of the kidney is a very rare subtype of renal neoplasms. There are only 27 cases reported in the literature since 1936. In addition, it has a high risk of metastasis and very low survival rate.

PATIENT'S CONCERNS

In this report, we present a case of unique large osteosarcoma originated from the left kidney (21 cm × 18 cm × 11 cm) with lung metastasis. A 48-year-old female patient presented with intermittent abdominal distension and gross hematuria.

DIAGNOSES

A computed tomography scan of the abdomen confirmed a large solid, partly calcified mass in the left retroperitoneum, with lung metastasis (IV stage according to AJCC). The radical nephrectomy was performed. The postoperation immunohistochemical analysis supporting the diagnosis of osteosarcoma.

INTERVENTIONS

The patient received chemotherapy with ifosfamide, cisplatinum, pirarubicin and then target therapy with anlotinib (12 mg per day, per os; days 1-14; 21 days per cycle) after surgery.

OUTCOMES

The patient was followed up for 26 months, with no postoperative complications, no tumor recurrence, and no progress in pulmonary metastasis.

LESSONS

The case reported here is a unique large osteosarcoma originated from the kidney (21 cm × 18 cm × 11 cm) at an advanced stage (IV). However, the patient's condition was controlled for at least 26 months after surgical resection and postoperative chemotherapy, which had never been reported in the literature before. Additionally, 3 mutated genes were found in the tissue by genetic testing, which we suspect that is the reason why this patient is sensitive to chemotherapy and thus has longer survival.

MiR-199b-5p promotes malignant progression of osteosarcoma by regulating HER2

PURPOSE

MicroRNAs (miRs) are endogenous, noncoding small RNAs that play a key role in regulating biological and pathological processes. The oncogenic properties of miR-199b-5p have been demonstrated in previous studies but the effect of miR-199b-5p on osteosarcoma (OS) has not yet been clarified. This study aimed to investigate the effect of miR-199b-5p on OS and the relationship between this miR and the pathological parameters and prognosis of OS.

METHODS

MiR-199b-5p expression in 57 pairs of OS tissues, corresponding adjacent normal tissues and OS cells was measured by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR).The relationship between miR-199b-5p and the pathological features and prognosis of OS patients was examined. We constructed small interfering (si) RNA to knock down miR-199b-5p expression in OS cell lines MG63 and U2OS. Cell Counting Kit-8 (CCK-8), cell cloning assay and Transwell cell migration and invasion assay were applied for investigating the biological function of miR-199b-5p, respectively. Finally, western blot was used for exploring its underlying mechanism.

RESULTS

MiR-199b-5p expression in OS was significantly higher than that of normal tissues. Compared to patients w\sith low expression of miR-199b-5p, patients with high expression level tended to be with younger age, higher incidence of distant metastases and lower overall survival. Compared with interference sequence negative control (si-NC) group, the abilities of proliferation, invasion and metastasis of cells transfected with si-miR-199b-5p were significantly decreased. Western blot analysis indicated that expressions of key proteins related to epithelial to mesenchymal transition (EMT) signaling pathway, including N-cadherin, Vimentin, β-catenin and matrix metalloproteinase-9 (MMP9), were significantly decreased after transfection with si-miR-199b-5p. Furthermore, we found that miR-199b-5p promoted the progression of OS mainly through regulating HER2.

CONCLUSIONS

Upregulated miR-199b-5p is significantly related with stage, distant metastasis and poor prognosis of OS. This MiR may promote progression of OS through regulating HER2.

Adrenal Gland Metastasis in Osteogenic Osteosarcoma. A Radiological Case Report

Adrenal gland metastases from osteogenic sarcoma are rare and an unusual pattern of relapse. The recognition of solitary metastases, particularly when located in uncommon sites is very important for subsequent treatment. The authors describe the radiological features of an adrenal metastases from osteogenic sarcoma.

Osteosarcoma of the Extremity Metastatic at Presentation: Results Achieved in 26 Patients Treated with Combined Therapy (Primary Chemotherapy Followed by Simultaneous Resection of the Primary and Metastatic Lesions)

From September 1986 to December 1989, 26 selected patients with high-grade osteosarcoma of the extremities metastatic at presentation were treated with primary chemotherapy (high doses of methotrexate, -cisplatinum and adriamycin) followed by surgery. Twenty-one cases underwent resections of the primary and metastatic tumor at the same time; owing to the disappearance of lung metastases after preoperative chemotherapy in 3 cases, only the primary tumor was operated on. Due to progression of the disease in 2 patients, no surgery was performed. Histologic examination of the resected specimen was performed to evaluate the percentage of necrosis produced by chemotherapy on the primary and metastatic tumor. After surgery, the patients received further chemotherapy with the same drugs used preoperatively plus ifosfamide and VP-16. The histologic response of the primary tumor was good (> 90 % tumor necrosis) in 25 % of the cases; in the resected metastatic nodules, 23 % had good responses. A discrepancy between the histologic response of the primary and secondary tumor was observed in only 15 % of the cases. These results seem to confirm the validity of the strategy (widely used today in the neoadjuvant treatment of non-metastatic osteosarcoma) of changing the postoperative treatment when the histologic response of the primary tumor is poor. At an average follow-up of 3.5 years, only 6 patients remained disease-free; 19 patients relapsed and 1 patient died for adriamycin cardiotoxicity. Of the 19 relapsed patients, 16 died and 3 are still alive but with uncontrolled disease. These results are much worse than those obtained in 144 cases of non-metastatic osteosarcoma of the extremities treated in the same period with the same preoperative chemotherapy (77 % with good response in the primary tumor and 78 % with continues disease-free survival). The data suggest that a very effective neoadjuvant chemotherapy for nonmetastatic osteosarcoma of the extremities gives disappointing results in osteosarcoma of the extremities which is metastatic at presentation.

Follow-Up Protocols in Orthopedic Oncology

Little has been written about the specific timing and elements involved in the follow-up of orthopedic oncology patients1,2,7. The experience with bone tumor treatment at the First Clinic of the Istituto Rizzoli started 30 years ago and more than 15,000 patients have been treated to date. The increment of limb salvage surgery is linked with the improvements in imaging and surgical skills and with the availability of new reconstructive techniques. For this purpose it is mandatory to carry out meticulous monitoring of the patients. A large number of patients are still followed up to evaluate the results in terms of oncological and functional status. Based on this experience we developed a time schedule to better respond to the need for adequate patient evaluation.

Prognosis for dogs with stage III osteosarcoma following treatment with amputation and chemotherapy with and without metastasectomy

OBJECTIVE To determine survival times of selected dogs with metastatic (stage III) osteosarcoma, whether disease-free interval (DFI) was associated with survival time after diagnosis of stage III disease (ie, stage III survival time), and whether a survival benefit of metastasectomy existed. DESIGN Retrospective case series with nested cohort study. ANIMALS 194 client-owned dogs treated for histologically confirmed appendicular osteosarcoma from 1997 through 2009. PROCEDURES Dogs were included if they had stage I or II osteosarcoma at the time of initial evaluation, had amputation of the affected appendage and ≥ 1 dose of chemotherapy afterward, and developed metastasis within the follow-up period or prior to death. Data collected from the medical records included signalment, primary tumor location, clinical and laboratory findings, whether metastasectomy was performed, and outcome. Various factors were examined for associations with outcome. RESULTS Dogs that received no treatment for the metastasis had a median survival time between 49 and 57 days after diagnosis of stage III osteosarcoma. Duration of the preceding DFI had no association with this period. Metastasectomy alone was associated with a longer median stage III survival time (232 days) than no metastasectomy (49 days). Among all dogs identified as qualifying for pulmonary metastasectomy on the basis of < 3 pulmonary nodules visible on thoracic radiographs and a DFI > 275 days (n = 21), a survival advantage was also identified for those that actually received pulmonary metastasectomy (6). CONCLUSIONS AND CLINICAL RELEVANCE Preceding DFI had no influence on survival time of dogs with stage III osteosarcoma. Metastasectomy was associated with an increase in survival time for selected dogs.

Quantitative Primary Tumor Indocyanine Green Measurements Predict Osteosarcoma Metastatic Lung Burden in a Mouse Model

BACKGROUND

Current preclinical osteosarcoma (OS) models largely focus on quantifying primary tumor burden. However, most fatalities from OS are caused by metastatic disease. The quantification of metastatic OS currently relies on CT, which is limited by motion artifact, requires intravenous contrast, and can be technically demanding in the preclinical setting. We describe the ability for indocyanine green (ICG) fluorescence angiography to quantify primary and metastatic OS in a previously validated orthotopic, immunocompetent mouse model.

QUESTIONS/PURPOSES

(1) Can near-infrared ICG fluorescence be used to attach a comparable, quantitative value to the primary OS tumor in our experimental mouse model? (2) Will primary tumor fluorescence differ in mice that go on to develop metastatic lung disease? (3) Does primary tumor fluorescence correlate with tumor volume measured with CT?

METHODS

Six groups of 4- to 6-week-old immunocompetent Balb/c mice (n = 6 per group) received paraphyseal injections into their left hindlimb proximal tibia consisting of variable numbers of K7M2 mouse OS cells. A hindlimb transfemoral amputation was performed 4 weeks after injection with euthanasia and lung extraction performed 10 weeks after injection. Histologic examination of lung and primary tumor specimens confirmed ICG localization only within the tumor bed.

RESULTS

Mice with visible or palpable tumor growth had greater hindlimb fluorescence (3.5 ± 2.3 arbitrary perfusion units [APU], defined as the fluorescence pixel return normalized by the detector) compared with those with a negative examination (0.71 ± 0.38 APU, -2.7 ± 0.5 mean difference, 95% confidence interval -3.7 to -1.8, p < 0.001). A strong linear trend (r = 0.81, p < 0.01) was observed between primary tumor and lung fluorescence, suggesting that quantitative ICG tumor fluorescence is directly related to eventual metastatic burden. We did not find a correlation (r = 0.04, p = 0.45) between normalized primary tumor fluorescence and CT volumetric measurements.

CONCLUSIONS

We demonstrate a novel methodology for quantifying primary and metastatic OS in a previously validated, immunocompetent, orthotopic mouse model. Quantitative fluorescence of the primary tumor with ICG angiography is linearly related to metastatic burden, a relationship that does not exist with respect to clinical tumor size. This highlights the potential utility of ICG near-infrared fluorescence imaging as a valuable preclinical proof-of-concept modality. Future experimental work will use this model to evaluate the efficacy of novel OS small molecule inhibitors.

CLINICAL RELEVANCE

Given the histologic localization of ICG to only the tumor bed, we envision the clinical use of ICG angiography as an intraoperative margin and tumor detector. Such a tool may be used as an alternative to intraoperative histology to confirm negative primary tumor margins or as a valuable tool for debulking surgeries in vulnerable anatomic locations. Because we have demonstrated the successful preservation of ICG in frozen tumor samples, future work will focus on blinded validation of this modality in observational human trials, comparing the ICG fluorescence of harvested tissue samples with fresh frozen pathology.

Endostar combined with chemotherapy in a pediatric osteosarcoma with pulmonary metastasis and malignant pleural effusion: A case report

RATIONALE

Angiogenesis is a key factor for tumor growth and metastasis both in cancer and sarcoma. Endostar, a novel safe and well-tolerated recombinant human endostatin, can suppress the expression of VEGF and the activation of ERK, MAPK, and AKT, and then inhibit tumor progression.

PATIENT CONCERNS

A pediatric osteosarcoma with pulmonary metastasis and malignant pleural effusion.

DIAGNOSES

Osteosarcoma with pulmonary metastasis and malignant pleural effusion.

INTERVENTIONS

Considering the physical condition of patient, the patient underwent surgical resection of the right lung lesion after receiving endostar combined with chemotherapy and maintained endostar alone for 47 cycles.

OUTCOMES

The patient obtained pathologic complete remission and had been in progression-free survival up to now.

LESSONS

Our experience could provide a treatment strategy for pediatric osteosarcoma patients with pulmonary metastasis and malignant pleural effusion.

Comparative Transcriptome Analysis Quantifies Immune Cell Transcript Levels, Metastatic Progression, and Survival in Osteosarcoma

Overall survival of patients with osteosarcoma (OS) has improved little in the past three decades, and better models for study are needed. OS is common in large dog breeds and is genetically inducible in mice, making the disease ideal for comparative genomic analyses across species. Understanding the level of conservation of intertumor transcriptional variation across species and how it is associated with progression to metastasis will enable us to more efficiently develop effective strategies to manage OS and to improve therapy. In this study, transcriptional profiles of OS tumors and cell lines derived from humans (n = 49), mice (n = 103), and dogs (n = 34) were generated using RNA sequencing. Conserved intertumor transcriptional variation was present in tumor sets from all three species and comprised gene clusters associated with cell cycle and mitosis and with the presence or absence of immune cells. Further, we developed a novel gene cluster expression summary score (GCESS) to quantify intertumor transcriptional variation and demonstrated that these GCESS values associated with patient outcome. Human OS tumors with GCESS values suggesting decreased immune cell presence were associated with metastasis and poor survival. We validated these results in an independent human OS tumor cohort and in 15 different tumor data sets obtained from The Cancer Genome Atlas. Our results suggest that quantification of immune cell absence and tumor cell proliferation may better inform therapeutic decisions and improve overall survival for OS patients.Significance: This study offers new tools to quantify tumor heterogeneity in osteosarcoma, identifying potentially useful prognostic biomarkers for metastatic progression and survival in patients. Cancer Res; 78(2); 326-37. ©2017 AACR.

pFAK-Y397 overexpression as both a prognostic and a predictive biomarker for patients with metastatic osteosarcoma

Focal adhesion kinase (FAK) is important for tumor cell survival and metastasis in various cancers. However, its expression and prognostic value in patients with metastatic osteosarcoma remain unknown. We investigated the expression of FAK and its phosphorylated form (pFAK-Y397) in osteosarcoma tissues from 53 patients by immunohistochemistry and evaluated their correlations with clinicopathologic characteristics and outcomes. The prognostic values were assessed using Kaplan-Meier survival and Cox regression analyses. Total FAK and pFAK-Y397 were overexpressed in 48 (90.6%) and 33 (62.3%) cases, respectively. pFAK-Y397 overexpression was correlated with poor histologic response after neoadjuvant chemotherapy in patients with osteosarcoma regardless of the presence of metastasis or not. Kaplan-Meier curve showed that patients with metastatic osteosarcoma with pFAK-Y397 overexpression had significantly worse overall survival (OS) than those with non-overexpression (P = 0.044). Multivariate Cox regression analysis confirmed pFAK-Y397 overexpression as an independent prognostic predictor for OS and post metastases OS (PMOS) (P = 0.017, P = 0.006, respectively). Age at diagnosis was also an independent indicator for PMOS (P = 0.003). However, total FAK expression was not correlated with any clinicopathologic characteristics or OS in patients with metastatic osteosarcoma. In conclusion, our findings identified FAK as a common aberrant protein overexpression in various subtypes of osteosarcoma. pFAK-Y397 overexpression can be used as a prognostic biomarker predicting poor OS for patients with metastatic osteosarcoma, and the expression of pFAK-Y397 differentiated good and poor responders to neoadjuvant chemotherapy.

Selection of Surgical Methods in the Treatment of Upper Tibia Osteosarcoma and Prognostic Analysis

BACKGROUND

We aimed to explore the clinical effects and prognosis of different surgical methods in upper tibia osteosarcoma.

METHODS

Among 112 patients with proximal upper tibia osteosarcoma, 40 patients were treated with amputation, 20 patients were treated with massive osteoarticular allograft, and the remaining 52 cases were treated with tumor resection and artificial joint replacement.

RESULTS

Recurrence was observed in 2 cases (5%) in the amputation group, in 6 cases (30%) in the massive osteoarticular allograft group, and in 6 cases (12%) in the tumor resection and artificial joint replacement group (P = 0.021). The lung metastasis rates were 40% in the amputation group, 40% in the massive osteoarticular allograft group, and 38% in the tumor resection and artificial joint replacement group (P = 0.986). The survival rates at 1, 3, and 5 years were 95%, 75%, and 45%, respectively, in the amputation group, 95%, 75%, and 35%, respectively, in the massive osteoarticular allograft group, and 92.3%, 78.8%, and 53.8%, respectively, in the tumor resection and artificial joint replacement group (P > 0.05).

CONCLUSIONS

The selection of the optimal surgical method for upper tibia osteosarcoma should be made according to the individual circumstances of the patient. Our study has significance for reducing the incidence of surgical complications and improving the quality of postoperative life.

Tricetin inhibits human osteosarcoma cells metastasis by transcriptionally repressing MMP-9 via p38 and Akt pathways

Tricetin, a dietary flavonoid, has cytostatic properties and anti-metastasis activities in various cancer cells. However, the detailed impacts and underlying mechanisms of tricetin on human osteosarcoma cell metastasis are still unclear. Here, the hypothesis that tricetin possesses the anti-metastatic effects on human osteosarcoma cells was tested. The effects of tricetin on cell viability, motility, migration, and invasion in human osteosarcoma U2OS and HOS cells were investigated. Gelatin zymography, western blotting, polymerase chain reaction (PCR), and the luciferase assay were used to further explore the underlying mechanisms involved in anti-metastatic effects in U2OS cells. Their results showed that Tricetin, up to 80 μM without cytotoxicity, attenuated U2OS and HOS cells motility, invasiveness, and migration by reducing matrix metalloproteinase (MMP)-9 enzyme activities. In U2OS cells, tricetin decreased MMP-9 protein and mRNA expressions, which was confirmed by real-time PCR. Next, tricetin reduced phosphorylation of p38 and Akt, but no effect on phosphorylation of ERK1/2 and JNK. In conclusion, tricetin possesses the anti-metastatic activity of osteosarcoma cells by transcriptionally repressing MMP-9 via p38 and Akt signaling pathways. This may be potentially useful as anti-metastatic agents for osteosarcoma chemotherapy.

A case report of apatinib in treating osteosarcoma with pulmonary metastases

RATIONALE

Osteosarcoma is the most common malignant bone tumor in children and adolescents. Pulmonary metastases lead to a significantly increased risk of death. Apatinib, a new potent oral small-molecule tyrosine kinase inhibitor targeting the intracellular domain of vascular endothelial growth factor receptor 2 (VEGFR-2), shows survival benefits in treating advanced or metastatic gastric adenocarcinoma, non-squamous non-small cell lung cancer and metastatic breast cancer. However, its efficacy in metastatic osteosarcoma has not been reported yet.

PATIENT CONCERNS

Herein, we presented a 50-year-old man patient who visited hospital due to local bone pain in the left leg.

DIAGNOSES

He was initially diagnosed with osteoblastic osteosarcoma.

INTERVENTIONS

The patient suffered repeated resection surgeries but developed multiple lung metastases. Positive staining for CD31, CD34, and VEGFR-2 were detected in the tumor section. As he refused to receive chemotherapy due to concerns regarding the chemotherapy toxicities and sorafenib due to high cost, apatinib was given at a dose of 500 mg daily.

OUTCOMES

Eleven months following apatinib administration, the patient achieved a partial response according to the RECIST 1.1 standard. No severe toxicity or drug-related side effect was observed during the treatment.

LESSONS

Therefore, apatinib could be a new option for the treatment of metastatic osteosarcoma. Clinical trials are required to further confirm the efficacy and safety of apatinib in treating pulmonary metastases from osteosarcoma.

[SURGICAL TREATMENT OF PATIENTS FOR METACHRONOUS METASTASES OF PULMONARY OSTEOSARCOMA. CLINICAL PROGNOSTIC FACTORS]

The impact of surgical method on results of complex treatment in patients, suffering the osteosarcoma metachronous pulmonary metastases, was studied. The survival indices in 93 patients were analyzed, of them in 71, suffering osteosarcoma - with complex treatment, including surgical intervention of complete excision of all metastases (three-years survival – 34.2%), and in 21 – complex treatment with palliative radiation therapy (three-year survival 3.7%). Trustworthy impact on three-years survival indices was proved for such clinical factors, as the terms of the metastases occurrence (6 mo and lesser, and more, than 6 mo) and quantity of metastases (up to 5, 5 and more) present.

Multidisciplinary approach to osteosarcoma

Osteosarcoma is a malignant bone tumor composed of mesenchymal cells producing osteoid and immature bone. Osteosarcoma is the most frequent primary malignant bone tumor, if we excluded myeloma, a haematologic disease. The incidence of osteosarcoma is 2-3/million/year, but is higher in adolescence, in which the annual incidence peaks at 8-11/million/year at 15-19 years of age. Local pain, followed by localized swelling and limitation of joint movement, are the typical signs and symptoms. Correct diagnosis can be achieved through a correct approach to the disease and the combination of clinical and radiographic aspects. The final step to confirm the diagnosis is the biopsy. Computer Tomography of the chest and Positron-Emission Tomography are mandatory to complete the staging, which is performed according the Musculoskeletal Tumor Society staging system. A multidisciplinary approach is needed both to get to a correct diagnosis (orthopaedic surgeon, radiologist and histopathologist) and to perform definitive treatment. Multidisciplinary approach should be performed in reference centers able to provide access to the full spectrum of care and where orthopaedic surgeon, oncologist, histopathologist, radiologist and radiotherapist can cooperate. The management of osteosarcoma is based primarily on neo-adjuvant and adjuvant chemotherapy and surgical resection; radiotherapy is not effective as osteosarcomas are relatively radioresistant. Prognostic factors include metastases at presentation, histologic response to induction chemotherapy, the site of the primary tumor (with axial lesions having an inferior outcome), serum lactate dehydrogenase and alkaline phosphatase levels.

[A Case of Pancreatic Metastasis of Osteosarcoma Resected Using Laparoscopic Spleen Preserving Distal Pancreatectomy]

A 44-year-old woman underwent surgical resection and received preoperative and postoperative chemotherapy for conventional osteosarcoma in the right fibular head. Three years later, follow-up PET-CT revealed accumulation ofFDG in the tail ofthe pancreas. Contrast-enhanced computed tomography showed a 13mm well-circumscribed hypovascular tumor. EUS showed a heterogeneous solid tumor, which was diagnosed as metastasis ofosteosarcoma to the pancreas. Laparoscopic spleen preserving distal pancreatectomy(LAP-SPDP)was performed. Pathologically, the tumor was diagnosed as metastasis ofconventional osteosarcoma to the pancreas. Cells from pancreas islet tissue were detected in the tumor, suggesting invasion ofthe tumor into the pancreatic body and surrounding adipose tissue. Although postoperative chemotherapy was administered, lung metastasis was detected 1.1 years after surgery. Laparoscopic partial resection of the lung metastasis was performed, and the patient is still alive. Metastasis ofosteosarcoma to the pancreas is rare, and there is no report oflaparoscopic approach as a treatment. Herein, we report a case with several references.

Generation of Osteosarcomas from a Combination of Rb Silencing and c-Myc Overexpression in Human Mesenchymal Stem Cells

Osteosarcoma (OS) was a malignant tumor occurring with unknown etiology that made prevention and early diagnosis difficult. Mesenchymal stem cells (MSCs), which were found in bone marrow, were claimed to be a possible origin of OS but with little direct evidence. We aimed to characterize OS cells transformed from human MSCs (hMSCs) and identify their association with human primary OS cells and patient survival. Genetic modification with p53 or retinoblastoma (Rb) knockdown and c-Myc or Ras overexpression was applied for hMSC transformation. Transformed cells were assayed for proliferation, differentiation, tumorigenecity, and gene expression profile. Only the combination of Rb knockdown and c-Myc overexpression successfully transformed hMSCs derived from four individual donors, with increasing cell proliferation, decreasing cell senescence rate, and increasing ability to form colonies and spheres in serum-free medium. These transformed cells lost the expression of certain surface markers, increased in osteogenic potential, and decreased in adipogenic potential. After injection in immunodeficient mice, these cells formed OS-like tumors, as evidenced by radiographic analyses and immunohistochemistry of various OS markers. Microarray with cluster analysis revealed that these transformed cells have gene profiles more similar to patient-derived primary OS cells than their normal MSC counterparts. Most importantly, comparison of OS patient tumor samples revealed that a combination of Rb loss and c-Myc overexpression correlated with a decrease in patient survival. This study successfully transformed human MSCs to OS-like cells by Rb knockdown and c-Myc overexpression that may be a useful platform for further investigation of preventive and target therapy for human OS. Stem Cells Translational Medicine 2017;6:512-526.

Matrix-Gla protein promotes osteosarcoma lung metastasis and associates with poor prognosis

Osteosarcoma (OS) is the most prevalent osseous tumour in children and adolescents and, within this, lung metastases remain one of the factors associated with a dismal prognosis. At present, the genetic determinants driving pulmonary metastasis are poorly understood. We adopted a novel strategy using robust filtering analysis of transcriptomic profiling in tumour osteoblastic cell populations derived from human chemo-naive primary tumours displaying extreme phenotypes (indolent versus metastatic) to uncover predictors associated with metastasis and poor survival. We identified MGP, encoding matrix-Gla protein (MGP), a non-collagenous matrix protein previously associated with the inhibition of arterial calcification. Using different orthotopic models, we found that ectopic expression of Mgp in murine and human OS cells led to a marked increase in lung metastasis. This effect was independent of the carboxylation of glutamic acid residues required for its physiological role. Abrogation of Mgp prevented lung metastatic activity, an effect that was rescued by forced expression. Mgp levels dramatically altered endothelial adhesion, trans-endothelial migration in vitro and tumour cell extravasation ability in vivo. Furthermore, Mgp modulated metalloproteinase activities and TGFβ-induced Smad2/3 phosphorylation. In the clinical setting, OS patients who developed lung metastases had high serum levels of MGP at diagnosis. Thus, MGP represents a novel adverse prognostic factor and a potential therapeutic target in OS. Microarray datasets may be found at: http://bioinfow.dep.usal.es/osteosarcoma/ Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

A novel model for the investigation of orthotopically growing primary and secondary bone tumours using intravital microscopy

Here is reported the development of an experimental model using intravital microscopy as a tool to orthotopically investigate malignant bone tumours. Although up to 85% of the most frequently occurring malignant solid tumours, such as lung and prostate carcinomas, metastasize into the bone, and despite the knowledge that a tumour's course may be altered by its surrounding tissue, there is no adequate experimental model available enabling the investigation of orthotopically grown bone tumours in vivo. Intravital microscopy is an internationally accepted experimental method, used in various acute and chronic animal models, that enables qualitative and quantitative analysis of the angiogenesis, microcirculation, growth behaviour, etc. of various benign and malignant tissues. Non-invasive investigations of up to several weeks are possible. Additionally, tissue samples can be taken after termination of the in vivo experiments for further ex vivo investigation (histology, immunohistochemistry, molecular biology, etc.), elucidating the mechanisms that underlie the in vivo observations. Severe combined immunodeficient mice were fitted with a cranial window preparation where the calvaria served as the site for orthotopic implantation of the solid human tumours Saos-2 osteosarcoma (primary) and A 549 lung carcinoma and PC-3 prostate carcinoma (secondary). In all preparations, the take rate was 100%. Histological assessment confirmed the data obtained in vivo, showing typical tumour growth with infiltration of the surrounding osseous and soft tissues. This novel model serves as a valuable tool in understanding the biology of primary and secondary bone tumours in physiological and pathophysiological situations, with implications for the most areas of tumour therapy such as chemotherapy, radiation and antiangiogenesis.

Malignant transformation of a high-grade osteoblastoma of the petrous apex with subcutaneous metastasis

We describe the clinical presentation, management, and pathologic findings in a case of osteosarcoma of the petrous apex with an atypical metastasis to the lower abdominal wall. We retrospectively reviewed the record of a 49-year-old man who was diagnosed with a right petrous apex lesion, which biopsy identified as a high-grade osteoblastoma. After two attempts at en bloc resection were not curative, radiation and chemotherapy were recommended. The patient subsequently developed a cutaneous lower abdominal mass that was diagnosed as an osteosarcoma. Meanwhile, the petrous apex tumor continued to grow despite treatment until the patient died from the burden of disease. Temporal bone osteoblastomas and osteosarcomas are both extremely rare, and they can be difficult to differentiate histologically. Our case illustrates this difficulty and demonstrates the possibility of a high-grade osteoblastoma's malignant conversion to an osteosarcoma.

A Rare Cause of Bowel Obstruction: Peritoneal Metastases in Osteosarcoma at the Tibia in a Young Female Patient with Brain Metastasis. Case Report

Osteosarcomas are the most frequent primary malignant bone tumors in children and adolescents. Like brain metastases in osteosarcomas, the bowel metastases are very rare. We present the case of a 23-year-old female patient, diagnosed and operated in 2008 of osteosarcoma at the tibia, for which she had sessions of neoadjuvant and adjuvant chemotherapy, but presented lungs metastases for which she underwent surgery in 2014. Then, in March 2015, she was diagnosed with an intracranial expansive process, an osteosarcoma metastasis, for which a total ablation of the tumor was performed during the early postoperatory period, being transferred to the General Surgery Clinic for abdominal pain, abdominal distention, vomiting, and lack of intestinal transit regarding faeces and intestinal gas. Both clinically and imagistically, the diagnosis was of bowel obstruction. This was the reason for performing surgery, thus discovering a bowel obstruction secondary to a metastasis of the terminal ileum and liver metastases that were confirmed as osteosarcoma metastases from an anatomopathological and immunohistochemical point of view. The bowel metastases and the osteosarcoma brain metastases are very rare entities and, their association, most often with young patients, is exceptional. However, bowel metastases must be taken into account as a possible cause of bowel obstruction in patients with osteosarcoma.

Malignant transformation of a unicameral bone cyst in a cat

A unicameral bone cyst in the proximal humerus of a 3-year-old Norwegian forest cat was diagnosed by dynamic contrast-enhanced magnetic resonance imaging, surgical exploration, and histopathology. Surgical curettage and incorporation of bone cement led to full recovery. An osteosarcoma developed at the surgical site 17 months later. Thoracic radiographs showed pulmonary lesions consistent with metastasis.

Unusual Cause of Spontaneous Bilateral Pneumothorax Secondary to Osteosarcoma Metastasis

Spontaneous pneumothorax is an emergency situation and early diagnosis and management is very important. Pneumothorax is rarely the first manifestation of lung metastasis. Spontaneous pneumothoraxes have been reported in some osteosarcoma patients. We hereby report a case of a bilateral spontaneous pneumothorax, revealing metastasis of an osteosarcoma.