Targeting CD44 by CRISPR-Cas9 in Multi-Drug Resistant Osteosarcoma Cells.

BACKGROUND/AIMS: Drug resistance is the main difficulty for the current treatment for osteosarcoma. Cluster of differentiation 44 (CD44) is a receptor for hyaluronic acid (HA) and HA-binding has been proven to participate in various biological tumor activities, including tumor progression, metastasis and drug resistance. In this study, we aimed to determine the effects of CD44 on migration, invasion, proliferation, and the drug-sensitivity of osteosarcoma. METHODS: 96 human osteosarcoma tissues from 56 patients were collected to evaluate the expression of CD44 in osteosarcoma tissue by immunohistochemistry. CRISPR-Cas9 system was used to specifically silence CD44 in drug-resistant cell lines (KHOSR2 and U-2OSR2). The migration and invasion activities of cells was demonstrated by wound healing and transwell invasion assay. The proliferation speed of the cells was detected under 3D cell culture condition. Drug resistance of cells was detected by MTT and drug uptake assay. RESULTS: The immunohistochemistry results demonstrated that a high level of CD44 may predict poor survival and higher potential of metastasis, recurrence and drug resistance in patients with osteosarcoma. After knocking-out of CD44 by the CRISPR-Cas9 system, not only the migration and invasion activities of osteosarcoma cells were significantly inhibited, but the drug sensitivity was also enhanced. CONCLUSION: CD44 silencing could inhibit the development of osteosarcoma migration, invasion, proliferation and ameliorate drug resistance to current treatment in osteosarcoma. This study applies new strategy to target CD44, which may improve the prognosis of osteosarcoma.

CRISPR-Cas9-Mediated Silencing of CD44 in Human Highly Metastatic Osteosarcoma Cells.

BACKGROUND/AIMS: Metastasis is the major cause of death in patients with osteosarcoma. There is an urgent need to identify molecular markers that promote metastasis. Cluster of differentiation 44 is a receptor for hyaluronic acid (HA) and HA-binding has been proven to participate in various biological tumor activities, including tumor progression and metastasis. METHODS: We performed a meta-analysis to investigate the relationship between CD44 expression, survival, and metastasis in patients with osteosarcoma. We then utilized the CRISPR-Cas9 system to specifically silence CD44 in highly metastatic human osteosarcoma cells (MNNG/HOS and 143B) and further determined the functional effects of CD44 knockout in these cells. RESULTS: The meta-analysis demonstrated that a high level of CD44 may predict poor survival and higher potential of metastasis in patients with osteosarcoma. The expression of CD44 in highly metastatic human osteosarcoma cell lines was efficiently blocked by CRISPR-Cas9. When CD44 was silenced, the proliferation and spheroid formation of these osteosarcoma cells was inhibited under 3-D culture conditions. Furthermore, the migratory and invasive functions were also impaired in these highly metastatic osteosarcoma cells. CONCLUSION: These results suggest that developing new strategies to target CD44 in osteosarcoma may prevent metastasis and improve the clinical outcome of osteosarcoma patients.

Nsc23925 prevents the development of paclitaxel resistance by inhibiting the introduction of P-glycoprotein and enhancing apoptosis.

Strategies to prevent the emergence of drug resistance will increase the effectiveness of chemotherapy treatment and prolong survival of women with ovarian cancer. The aim of our study is to determine the effects of NSC23925 on preventing the development of paclitaxel resistance in ovarian cancer both in cultured cells in vitro and in mouse xenograft models in vivo, and to further elucidate these underlying mechanisms. We first developed a paclitaxel-resistant ovarian cancer cell line, and demonstrated that NSC23925 could prevent the introduction of paclitaxel resistance by specifically inhibiting the overexpression of P-glycoprotein (Pgp) in vitro. The paclitaxel-resistant ovarian cancer cells were then established in a mouse model by continuous paclitaxel treatment in combination with or without NSC23925 administration in the mice. The majority of mice continuously treated with paclitaxel alone eventually developed paclitaxel resistance with overexpression of Pgp and antiapoptotic proteins, whereas mice remained sensitivity to paclitaxel and displayed lower expression levels of Pgp and antiapoptotic proteins after administered continuously with combination of paclitaxel-NSC23925. Paclitaxel-NSC23925-treated mice experienced significantly longer overall survival time than paclitaxel-treated mice. Furthermore, the combination of paclitaxel and NSC23925 therapy did not induce obvious toxicity as measured by mice body weight changes, blood cell counts and histology of internal organs. Collectively, our observations provide evidence that NSC23925 in combination with paclitaxel may prevent the onset of Pgp or antiapoptotic-mediated paclitaxel resistance, and improve the long-term clinical outcome in patients with ovarian cancer.

NSC23925 prevents the emergence of multidrug resistance in ovarian cancer in vitro and in vivo.

OBJECTIVE: The development of multidrug resistance (MDR) remains the significant clinical challenge in ovarian cancer therapy; however, relatively little is known about how to prevent the emergence of MDR during chemotherapy treatment. NSC23925 previously has been shown to prevent the development of MDR in osteosarcoma cells in vitro. The purpose of this study was to evaluate the effects of NSC23925 on the prevention of MDR in ovarian cancer, especially in vivo. METHODS: Human ovarian cancer cells were treated with paclitaxel alone or in combination with NSC23925 in vitro and in vivo. MDR ovarian cancer cells were established both in cultured cells and mouse models. The expression levels of Pgp and MDR1 were evaluated in various selected cell sublines by Western blot and real-time PCR. Pgp activity was also determined. RESULTS: Paclitaxel treated cells eventually developed MDR with overexpression of Pgp and MDR1, and with high activity of Pgp, while paclitaxel-NSC23925 co-treated cells remained sensitive to chemotherapeutic agents in both in vitro and in vivo models. There was no observed increase in expression level and activity of Pgp in paclitaxel-NSC23925 co-treated cells. Additionally, there were no changes in the sensitivity to chemotherapeutic agents, nor expression of Pgp, in cells cultured with NSC23925. CONCLUSION: Our findings suggest that NSC23925 can prevent the emergence of MDR in ovarian cancer both in vitro and in vivo. The clinical use of NSC2395 at the onset of chemotherapy may prevent the development of MDR and improve the clinical outcome of patients with ovarian cancer.

A-770041 reverses paclitaxel and doxorubicin resistance in osteosarcoma cells.

BACKGROUND: Reversing multidrug resistance (MDR) has been an important goal for clinical and investigational oncologists. In the last few decades, significant effort has been made to search for inhibitors to reverse MDR by targeting ATP-binding cassette (ABC) transporters (Pgp, MRP) directly, but these efforts have achieved little clinical success. Protein kinases play important roles in many aspects of tumor cell growth and survival. Combinations of kinase inhibitors and chemotherapeutics have been observed to overcome cancer drug resistance in certain circumstances. METHODS: We screened a kinase specific inhibitor compound library in human osteosarcoma MDR cell lines to identify inhibitors that were capable of reversing chemoresistance to doxorubicin and paclitaxel. RESULTS: We identified 18 small molecules that significantly increase chemotherapy drug-induced cell death in human osteosarcoma MDR cell lines U-2OSMR and KHOSR2. We identified A-770041 as one of the most effective MDR reversing agents when combined with doxorubicin or paclitaxel. A-770041 is a potent Src family kinase (Lck and Src) inhibitor. Western blot analysis revealed A-770041 inhibits both Src and Lck activation and expression. Inhibition of Src expression in U-2OSMR and KHOSR2 cell lines using lentiviral shRNA also resulted in increased doxorubicin and paclitaxel drug sensitivity. A-770041 increases the intracellular drug accumulation as demonstrated by calcein AM assay. CONCLUSIONS: These results indicate that small molecule inhibitor A-770041 may function to reverse ABCB1/Pgp-mediated chemotherapy drug resistance. Combination of Src family kinase inhibitor with regular chemotherapy drug could be clinically effective in MDR osteosarcoma.

Giant cell tumor of bone.

Giant cell tumor (GCT) of bone is one type of giant cell-rich lesion of bone. This benign mesenchymal tumor has characteristic multinuclear giant cells. Mononuclear stromal cells are the physiologically active and diagnostic cell type. Most GCTs are located in the epiphyseal regions of long bones. The axial skeleton-primarily the sacrum-is a secondary site of involvement. Most patients present with pain, swelling, joint effusion, and disability in the third and fourth decades of life. Imaging studies are important for tumor staging and radiographic grading. Typically, these clinically active but slow-growing tumors are confined to bone, with relatively well-defined radiographic borders. Monostotic disease is most common. Metastatic spread to the lungs is rare. Extended intralesional curettage with or without adjuvant therapy is the primary treatment choice. Local recurrence is seen in ≤ 20% of cases, and a second local intralesional procedure is typically sufficient in cases that are detected early. Medical therapies include diphosphonates and denosumab. Denosumab has been approved for use in osteoporosis as well as breast and prostate cancer metastatic to bone. Medical therapy and radiotherapy can alter the management of GCT of bone, especially in multifocal disease, local recurrences, and bulky central/axial disease.

Malignant lymphoma of bone: a review of 119 patients.

BACKGROUND: Lymphoma of bone is uncommon. As a result of this, many aspects of primary lymphoma of bone (PLB) are controversial: the definition, treatment strategies, response criteria, and prognostic factors. QUESTIONS/PURPOSES: We sought to determine the following in an analysis from a single center over a four-decade period: (1) 5-year disease-free survival of patients with PLB as well as those with systemic lymphoma with bone involvement; and (2) whether prognostic factors (sex, site of tumor, age) were associated with 5-year survival. METHODS: A total of 119 patients with lymphoma involving the musculoskeletal system were retrospectively evaluated. Among these, 94 patients who had a minimum followup of 6 months (mean, 67 months; range, 6 months to 34 years) were further analyzed for the skeletal site of involvement, the orthopaedic intervention(s) needed, and survival. The overall median age was 45 years (range, 7-87 years). The female-to-male ratio was 1:1.53. There were 70 (65 unifocal, five multifocal) patients with PLB. The femur was the most frequent site involved. Appendicular skeleton involvement was substantially higher in patients with PLB. Thirty-four (36%) patients had at least one surgical intervention. Fourteen patients (41%) needed more than one major surgical intervention. RESULTS: The disease-free 5-year survival for patients with PLB was 81% and for the patients with systemic lymphoma with bone involvement, it was 44%. The disease-free 5-year survival of the patients with PLB younger than 60 years old and 60 years old or older was 90% and 62%, respectively. Age was the only prognostic factor on survival of patients with PLB. CONCLUSIONS: Orthopaedic intervention was usually needed for pathologic fractures, avascular necrosis, spinal cord compression, or for the lesions of the weightbearing bones compromising stability or joint motion. The potential for long-term survival suggests the use of implants and techniques that have the best chance of long-term success.

Development of a new pre-vascularized tissue-engineered construct using pre-differentiated rADSCs, arteriovenous vascular bundle and porous nano-hydroxyapatide-polyamide 66 scaffold.

BACKGROUND: Development of a pre-vascularized tissue-engineered construct with intrinsic vascular system for cell growth and tissue formation still faces many difficulties due to the complexity of the vascular network of natural bone tissue. The present study was to design and form a new vascularized tissue-engineered construct using pre-differentiated rADSCs, arteriovenous vascular bundle and porous nHA-PA 66 scaffold. METHODS: rADSCs were pre-differentiated to endothelial cells (rADSCs-Endo) and then incorporated in nHA-PA 66 scaffolds in vitro. Subsequently, in vivo experiments were carried out according to the following groups: Group A (rADSCs-Endo/nHA-PA 66 scaffold with arteriovenous vascular bundle), Group B (rADSCs/nHA-PA 66 scaffold with arteriovenous vascular bundle); Group C (nHA-PA66 scaffold with arteriovenous vascular bundle), Group D (nHA-PA 66 scaffold only). The vessel density and vessel diameter were measured based on histological and immunohistochemical evaluation, furthermore, the VEGF-C, FGF-2 and BMP-2 protein expressions were also evaluated by western blot analysis. RESULTS: The results of in vivo experiments showed that the vessel density and vessel diameter in group A were significantly higher than the other three groups. Between Group B and C, no statistical difference was observed at each time point. In accordance with the results, there were dramatically higher expressions of VEGF-C and FGF-2 protein in Group A than that of Group B, C and D at 2 or 4 weeks. Statistical differences were not observed in VEGF-C and FGF-2 expression between Group B and C. BMP-2 was not expressed in any group at each time point. CONCLUSIONS: Compared with muscular wrapping method, arteriovenous vascular bundle implantation could promote vascularization of the scaffold; and the angiogenesis of the scaffold was significantly accelerated when pre-differentiated rADSCs (endothelial differentiation) were added. These positive results implicate the combination of pre-differentiated rADSCs (endothelial differentiation) and arteriovenous vascular bundle may achieve rapidly angiogenesis of biomaterial scaffold.

Inhibition of polo-like kinase 1 leads to the suppression of osteosarcoma cell growth in vitro and in vivo.

Osteosarcoma is the most common type of primary bone cancer in children and adolescents. Treatment options for osteosarcoma may include surgery, chemotherapy, and radiotherapy. Unfortunately, many patients eventually relapse, resulting in an unsatisfactory outcome. The serine/threonine-specific polo-like kinase 1 (PLK1) is a kinase that plays an important role in mitosis and the maintenance of genomic stability. PLK1 has been found to be highly expressed in the malignant cells of osteosarcoma. Here, we describe the in-vitro and in-vivo effects of BI 2536, a small-molecule inhibitor of PLK1, which through inhibiting PLK1 enzymatic activity, causes mitotic arrest and eventually induces cancer cell apoptosis. In this study, we show that the PLK1 inhibitor, BI 2536, inhibits proliferation and induces apoptosis in two-dimensional and three-dimensional cultures of osteosarcoma cell lines, KHOS and U-2OS. A proliferation assay performed both in two-dimensional and three-dimensional culture showed that the growth of both cell lines was inhibited by BI 2536. Cell cycle analysis showed that the cells treated with BI 2536 were mainly arrested in the G2/M phase. Immunofluorescence and western blotting analysis confirmed that the administration of BI 2536 led to significant decrease of PLK1 and Mcl-1 protein expression levels in dose-dependent and time-dependent manners. Furthermore, BI 2536-induced apoptosis in the osteosarcoma cell lines was shown by poly (ADP-ribose) polymerase cleavage and caspase assay. Finally, in mouse osteosarcoma xenografts, BI 2536-treated mice had significantly smaller tumors compared with the control mice. These findings offer evidence of the potential role for targeting PLK1 in osteosarcoma therapy.

Pigmented villonodular synovitis of joints.

OBJECTIVES: The objective of this study is to present two series of cases of pigmented villonodular disease of joints (PVNS) treated at different periods. The 215 cases from our hospital are current (1972-2009) and those 62 from the Jaffe collection from 1920 to 1968. METHODS: By use of our computerized tumor data system we were able to define age, gender, site, treatment, complications, and outcome. Examination of the material from the Jaffe collection included all of the above primary data but none on treatment and outcome. RESULTS: The data for the two systems studied were remarkably similar. The average ages were in mid years and the disorder was more frequent in females. The largest numbers of cases for both series were in the knee and foot and less commonly in hip, shoulder, and hand. The treatments were mostly surgical excision with the exception of the hip which required total hip replacement. The results show only a small number of recurrences, no metastatic disease and no deaths. CONCLUSION: Pigmented villonodular disease of joints is a rare entity, mostly occurring in the knee and foot. The principal treatment is surgical excision which is most often successful in these sites but leads to problems at other locations, especially the hip.

Osteoid osteoma and osteoblastoma.

Osteoid osteoma and osteoblastoma are commonly seen benign osteogenic bone neoplasms. Both tumors are typically seen in the second decade of life, with a notable predilection in males. Histologically, these tumors resemble each other, with characteristically increased osteoid tissue formation surrounded by vascular fibrous stroma and perilesional sclerosis. However, osteoblastomas are larger than osteoid osteomas, and they exhibit greater osteoid production and vascularity. Clinically, osteoid osteoma most commonly occurs in the long bones (eg, femur, tibia). The lesions cause night pain that is relieved with nonsteroidal anti-inflammatory drugs (NSAIDs). Osteoblastoma is most frequently located in the axial skeleton, and the pain is usually not worse at night and is less likely to be relieved with NSAIDs. Osteoblastoma can be locally aggressive; osteoid osteoma lacks growth potential. Osteoid osteoma may be managed nonsurgically with NSAIDs. When surgery is required, minimally invasive methods (eg, CT-guided excision, radiofrequency ablation) are preferred. Osteoblastoma has a higher rate of recurrence than does osteoid osteoma, and patients must be treated surgically with intralesional curettage or en bloc resection.

The kinase Mirk is a potential therapeutic target in osteosarcoma.

Osteosarcoma is the most common primary malignant bone tumor affecting children and adolescents. The majority of patients are treated by surgery and chemotherapy but have limited alternative therapeutic options. Kinases play an important role in the growth and survival of tumor cells. We aim to identify specific kinases to be vital in the survival of osteosarcoma cells and thus may be a key target in creating novel anticancer therapies. A lentiviral short hairpin RNA kinase library, screened osteosarcoma cells, identified kinase minibrain-related kinase (Mirk) (Dyrk1B) as a potential target. Knockdown Mirk expression could inhibit cell growth and induce apoptosis. Chemically synthetic small interfering RNA knockdown and complementary DNA rescue assay further confirmed the results from the decrease of Mirk gene expression. The relationship between Mirk gene expression and the clinical characteristics of patients with osteosarcoma was investigated using tissue microarray and immunohistochemistry analysis. The data indicate that the overall survival rate of patients with Mirk high staining (high levels of Mirk protein expression) is significantly shorter than those with Mirk low staining and moderate staining. This highlights Mirk's potential to serve as a promising target for molecular therapy in the treatment of osteosarcoma.

A validated disease severity scoring system for adults with type 1 Gaucher disease.

PURPOSE: A validated disease severity scoring system (DS3) for Gaucher disease type 1 (GD1) is needed to standardize patient monitoring and to define patient cohorts in clinical studies. METHODS: DS3 domains were established by an expert physician group using the nominal group technique of consensus formation. Items were selected by 36 GD1 physicians. The expert group determined appropriate measurement techniques for each item. Measurements were weighted considering contributions to GD1 morbidity and mortality. Consensus Clinical Global Impression Severity scores for sample cases were compared with average DS3 scores. A minimal clinically important difference in GD1 DS3 score was calculated. RESULTS: The GD1 DS3 includes bone (42% of score), hematologic (32%), and visceral domains (26%); individual items use routine assessments, including medical history, blood chemistry, organ volume measurements, and bone evaluations (magnetic resonance imaging and dual x-ray absorptiometry). The maximum score is 19. Interrater reliability was 0.97 (Cohen's kappa). DS3 scores were highly correlated with Clinical Global Impression Severity scores (r2 = 0.89). The minimal clinically important difference was -3.2 improvement and +3.9 deterioration. CONCLUSION: This DS3 accurately quantifies GD1 status and intrapatient change over time. Testing of reliability and validity will continue to allow eventual implementation of the DS3 in clinical studies and routine practice.

Oleanane triterpenoid CDDO-Me induces apoptosis in multidrug resistant osteosarcoma cells through inhibition of Stat3 pathway.

BACKGROUND: The activation of signal transducer and activator of transcription 3 (Stat3) pathway correlates with tumor growth, survival, drug resistance and poor prognosis in osteosarcoma. To explore the potential therapeutic values of this pathway, we assessed both the expression and the activation of Stat3 pathway in several pairs of multidrug resistant (MDR) osteosarcoma cell lines, and tissues. To explore the potential therapeutic values of this pathway, we analyzed the ability of the synthetic oleanane triterpenoid, C-28 methyl ester of 2-cyano-3,12-dioxoolen-1,9-dien-28-oic acid (CDDO-Me), to inhibit Stat3 expression and activation as well as its effects on doxorubicin sensitivity in osteosarcoma cells. METHODS: Expression of Stat3, phosphorylated Stat3 (pStat3) and Stat3 targeted proteins, including Bcl-XL, Survivin and MCL-1 were determined in drug sensitive and MDR osteosarcoma cell lines and tissues by Western blot analysis. The effect of CDDO-Me on osteosarcoma cell growth was evaluated by MTT and apoptosis by PARP cleavage assay and caspase-3/7 activity. RESULTS: Stat3 pathway was activated in osteosarcoma tissues and in MDR cell lines. CDDO-Me inhibited growth and induced apoptosis in osteosarcoma cell lines. Treatment with CDDO-Me significantly decreased the level of nuclear translocation and phosphorylation of Stat3. The inhibition of Stat3 pathway correlated with the suppression of the anti-apoptotic Stat3 targeted genes Bcl-XL, survivin, and MCL-1. Furthermore, CDDO-Me increased the cytotoxic effects of doxorubicin in the MDR osteosarcoma cell lines. CONCLUSIONS: Stat3 pathway is overexpressed in MDR osteosarcoma cells. CDDO-Me significantly inhibited Stat3 phosphorylation, Stat3 nuclear translocation and induced apoptosis in osteosarcoma. This study provides the framework for the clinical evaluation of CDDO-Me, either as monotherapy or perhaps even more effectively in combination with doxorubicin to treat osteosarcoma and overcome drug resistance.

Extra-abdominal desmoid tumors: a report of 234 cases.

BACKGROUND/OBJECTIVES: To report on the clinical presentation and outcome for 234 patients with extra-abdominal desmoids tumors. METHODS: Since 1977, the authors have treated 234 patients with extra-abdominal desmoid tumors. The patients had an average age of 36.7 and 61% were female. The tumors arose adjacent to muscles or bones and the largest number were in the foot, shoulder thigh and calf. All of the patients were treated by primary surgery. Thirty-seven had additional radiation and eight had chemotherapy. RESULTS: Local recurrence occurred in 39 patients and 23% of the patients required additional surgery. Of great concern were 24 patients who developed multiple sites metachronously, which required further surgery and in many cases caused disability. None of the patients died of disease but 5 required amputations. CONCLUSIONS: The authors concluded that despite the benign nature of the disease, these patients are difficult to treat and the results are sometimes considerably less than optimal.

Proximal femoral allograft: prognostic indicators.

Between 1972 and 1999, the Orthopedic Oncology Service treated 150 patients with resection and allograft transplantation of the proximal femur. Of the group, 121 patients had malignant tumors of the proximal femur and 29 had benign disorders. Four types of allografts were used: osteoarticular (46 patients), allograft-prosthesis (73), intercalary (20), and allograft-arthrodesis (5). Only 16% of the patients died of disease and 3% required amputation. The overall success rate for the series was 77% with the best results for the allograft prosthetic (82%) and intercalary procedures (87%). Graft infection (15 patients), allograft fracture (26 patients), and local recurrence (11 patients) most markedly affected outcome. With the exception of deaths of disease, no significant outcome difference occurred between the patients with malignant and benign disorders. In conclusion, allograft implantation especially for aggressive or malignant tumors of the proximal femur appears to be a competent system for therapy.

Multidrug resistant osteosarcoma cell lines exhibit deficiency of GADD45alpha expression.

To identify apoptosis genes involved in the multidrug resistance of osteosarcoma, a multidrug resistant human osteosarcoma cell line (U-2 OS MR) was established. Apoptosis gene microarray analysis demonstrated that GADD45alpha was significantly induced in U-2 OS cells after exposure to paclitaxel (P < 0.0001). However, the induction of GADD45alpha did not occur in U-2 OS MR cells. Subsequent analysis by Western blot confirmed that the expression of GADD45alpha could be significantly induced by paclitaxel and doxorubicin in U-2 OS cells but not in U-2 OS MR cells. Furthermore, the paclitaxel or doxorubicin treated U-2 OS and KH OS cells have a higher percentage of apoptotic cells when compared with U-2 OS MR and KH OS R2 cells treated with the same drugs. When GADD45alpha was transfected into U-2 OS MR or KH OS R2 and expressed, the cells became more sensitive to chemotherapeutic drugs. These results suggest that GADD45alpha may play a role in drug-induced apoptosis, as well as multidrug resistance in osteosarcoma cells.

Doxorubicin loaded Polymeric Nanoparticulate Delivery System to overcome drug resistance in osteosarcoma.

BACKGROUND: Drug resistance is a primary hindrance for the efficiency of chemotherapy against osteosarcoma. Although chemotherapy has improved the prognosis of osteosarcoma patients dramatically after introduction of neo-adjuvant therapy in the early 1980's, the outcome has since reached plateau at approximately 70% for 5 year survival. The remaining 30% of the patients eventually develop resistance to multiple types of chemotherapy. In order to overcome both the dose-limiting side effects of conventional chemotherapeutic agents and the therapeutic failure incurred from multidrug resistant (MDR) tumor cells, we explored the possibility of loading doxorubicin onto biocompatible, lipid-modified dextran-based polymeric nanoparticles and evaluated the efficacy. METHODS: Doxorubicin was loaded onto a lipid-modified dextran based polymeric nano-system. The effect of various concentrations of doxorubicin alone or nanoparticle loaded doxorubicin on KHOS, KHOSR2, U-2OS, and U-2OSR2 cells was analyzed. Effects on drug retention, immunofluorescence, Pgp expression, and induction of apoptosis were also analyzed. RESULTS: Dextran nanoparticles loaded with doxorubicin had a curative effect on multidrug resistant osteosarcoma cell lines by increasing the amount of drug accumulation in the nucleus via Pgp independent pathway. Nanoparticles loaded with doxorubicin also showed increased apoptosis in osteosarcoma cells as compared with doxorubicin alone. CONCLUSION: Lipid-modified dextran nanoparticles loaded with doxorubicin showed pronounced anti-proliferative effects against osteosarcoma cell lines. These findings may lead to new treatment options for MDR osteosarcoma.