The DNA damage checkpoint is activated during residual tumour cell survival to methotrexate treatment as an initial step of acquired drug resistance

Efficacy of Recombinant Human Endostatin plus Neoadjuvant Chemotherapy for Osteosarcoma and Its Influence on Serum VEGF and MMP-9 Levels

Objective

To investigate the efficacy of recombinant human endostatin (rh-Endo) plus neoadjuvant chemotherapy (NACT) for osteosarcoma (OSA) and its influence on serum vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9).

Methods

The case data of 141 OSA patients presented to the North District, Xiangyang Central Hospital Affiliated to Hubei University of Arts and Sciences from January 2018 to June 2019, were analyzed retrospectively. Patients receiving NACT (methotrexate + ifosfamide + adriamycin) were assigned into the control group (CNG; n = 65), while those treated with rh-Endo plus NACT were included in the combination group (CMG; n = 76). The following aspects were compared: clinical efficacy, serum tumor markers, serum VEGF and MMP-9 contents, inflammatory factors, incidence of adverse reactions, limb function scores at 6 months of follow-up, and prognostic quality of life (QOL).

Results

A statistically higher overall response rate (ORR) was determined in CMG versus CNG (84.2% vs. 64.6%, P < 0.05). The pretreatment serum bone alkaline phosphatase (BALP), insulin-like growth factor (IGF)-1, serum amyloid A (SAA), VEGF, MMP-9, C-reactive protein (CRP), tumor necrosis factor (TNF)-α, and interleukin (IL)-10 levels differed insignificantly between the two cohorts (P > 0.05); while except IL-10 that showed increased expression in both cohorts and was comparatively higher in CMG, the other 8 parameters reduced in both cohorts after 2 weeks of drug withdrawal, and the reduction of each parameter was more significant in CMG (P < 0.05). The total adverse reaction rate was 30.2% in CMG, which was higher than that of 36.9% in CNG, albeit without a statistical difference (P > 0.05). An evidently higher 2-year survival rate was determined in CMG (P < 0.05).

Conclusions

rh-Endo plus NACT is more effective than NACT alone in the treatment of osteosarcoma, which can validly restore the balance of vascular endothelial cells, reduce inflammation, and is worth promoting in clinic.

mTORC1 Inhibition Induces Resistance to Methotrexate and 6-Mercaptopurine in Ph+ and Ph-like B-ALL

Elevated activity of mTOR is associated with poor prognosis and higher incidence of relapse in B-cell acute lymphoblastic leukemia (B-ALL). Thus, ongoing clinical trials are testing mTOR inhibitors in combination with chemotherapy in B-ALL. However, the combination of mTOR inhibitors with standard of care chemotherapy drugs has not been studied extensively in high-risk B-ALL subtypes. Therefore, we tested whether mTOR inhibition can augment the efficacy of current chemotherapy agents in Ph⁺ and Ph-like B-ALL models. Surprisingly, inhibiting mTOR complex 1 (mTORC1) protected B-ALL cells from killing by methotrexate and 6-mercaptopurine, two antimetabolite drugs used in maintenance chemotherapy. The cytoprotective effects correlated with decreased cell-cycle progression and were recapitulated using cell-cycle inhibitors, palbociclib or aphidicolin. Dasatinib, a tyrosine kinase inhibitor currently used in Ph⁺ patients, inhibits ABL kinase upstream of mTOR. Dasatinib resistance is mainly caused by ABL kinase mutations, but is also observed in a subset of ABL unmutated cases. We identified dasatinib-resistant Ph+ cell lines and patient samples in which dasatinib can effectively reduce ABL kinase activity and mTORC1 signaling without causing cell death. In these cases, dasatinib protected leukemia cells from killing by 6-mercaptopurine. Using xenograft models, we observed that mTOR inhibition or dasatinib increased the numbers of leukemia cells that emerge after cessation of chemotherapy treatment. These results demonstrate that inhibitors targeting mTOR or upstream signaling nodes should be used with caution when combined with chemotherapeutic agents that rely on cell-cycle progression to kill B-ALL cells. Mol Cancer Ther; 16(9); 1942-53. ©2017 AACR.

Genome Analysis of Osteosarcoma Progression Samples Identifies FGFR1 Overexpression as a Potential Treatment Target and CHM as a Candidate Tumor Suppressor Gene

Osteosarcoma (OS) is the most common primary malignant tumor of bone, showing complex chromosomal rearrangements but with few known consistent changes. Deeper biological understanding is crucial to find new therapies to improve patient survival. We have sequenced the whole exome of two primary tumors (before and after chemotherapy), one metastatic tumor and a matched normal sample from two OS patients, to identify mutations involved in cancer biology. The metastatic samples were also RNA sequenced. By RNA sequencing we identified dysregulated expression levels of drug resistance- and apoptosis-related genes. Two fusion transcripts were identified in one patient (OS111); the first resulted in p53 inactivation by fusing the first exon of TP53 to the fifth exon of FAM45A. The second fusion joined the two first exons of FGFR1 to the second exon of ZNF343. Furthermore, FGFR1 was amplified and highly expressed, representing a potential treatment target in this patient. Whole exome sequencing revealed large intertumor heterogeneity, with surprisingly few shared mutations. Careful evaluation and validation of the data sets revealed a number of artefacts, but one recurrent mutation was validated, a nonsense mutation in CHM (patient OS106), which also was the mutation with the highest expression frequency (53%). The second patient (OS111) had wild-type CHM, but a downregulated expression level. In a panel of 71 clinical samples, we confirmed significant low expression of CHM compared to the controls (p = 0.003). Furthermore, by analyzing public datasets, we identified a significant association between low expression and poor survival in two other cancer types. Together, these results suggest CHM as a candidate tumor suppressor gene that warrants further investigation.

Melanoma coordinates general and cell-specific mechanisms to promote methotrexate resistance

Melanoma, the most aggressive form of skin cancer, is notoriously resistant to all current modalities of cancer therapy, including to the drug methotrexate. Melanosomal sequestration and cellular exportation of methotrexate have been proposed to be important melanoma-specific mechanisms that contribute to the resistance of melanoma to methotrexate. In addition, other mechanisms of resistance that are present in most epithelial cancer cells are also operative in melanoma. This report elucidates how melanoma orchestrates these mechanisms to become extremely resistant to methotrexate, where both E2F1 and checkpoint kinase 1 (Chk1), two molecules with dual roles in survival/apoptosis, play prominent roles. The results indicated that MTX induced the depletion of dihydrofolate in melanoma cells, which stimulated the transcriptional activity of E2F1. The elevate expression of dihydrofolate reductase and thymidylate synthase, two E2F1-target genes involved in folate metabolism and required for G(1) progression, favored dTTP accumulation, which promoted DNA single strand breaks and the subsequent activation of Chk1. Under these conditions, melanoma cells are protected from apoptosis by arresting their cell cycle in S phase. Excess of dTTP could also inhibit E2F1-mediated apoptosis in melanoma cells.

Wnt5a as a predictor in poor clinical outcome of patients and a mediator in chemoresistance of ovarian cancer

INTRODUCTION

Wnt5a regulates numerous signaling pathways controlling a wide range of cellular processes, including cell proliferation, differentiation, and apoptosis. However, it is still unclear whether Wnt5a is involved in mediating chemoresistance in cancer. We studied the correlation of Wnt5a expression with clinicopathologic parameters and survival in epithelial ovarian cancer and the effect of Wnt5a expression on chemoresistance of ovarian cancer cells.

METHODS

Wnt5a expression was immunohistochemically examined in ovarian cancer, benign tumor, and normal ovarian tissues. Two stable cell lines were established, namely, SKOV3/Wnt5a, which overexpressed Wnt5a, and SKOV3/miRNA, which downregulated Wnt5a expression using microRNA (miRNA). Wnt5a expression level was evaluated by semiquantitative reverse transcription-polymerase chain reaction, Western blot analysis, and immunofluorescence assay. The sensitivity of all transfected and untransfected cell lines to chemotherapeutic drugs (paclitaxel, oxaliplatin, 5-fluorouracil, epirubicin, and etoposide) was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay.

RESULTS

Wnt5a was found to be significantly higher in ovarian cancer compared with benign tumors and normal ovaries. High levels of Wnt5a expression were associated with the International Federation of Gynecology and Obstetrics stage and significantly predicted a poorer overall survival and progression-free survival compared with low Wnt5a expression. In addition, Wnt5a overexpression in SKOV3/Wnt5a cells decreased chemosensitivity compared with normal and empty vector controls (P < 0.05). Alternatively, Wnt5a down-regulation in SKOV3/miRNA cells led to a significant increase in chemosensitivity (P < 0.05).

CONCLUSIONS

Wnt5a immunoreactivity may be a useful prognostic indicator in patients with ovarian cancer. These results clarified for the first time the possibility that Wnt5a plays an important role in regulating chemosensitivity to anticancer drugs in ovarian cancer cells.

S100P sensitizes ovarian cancer cells to carboplatin and paclitaxel in vitro

OBJECTIVE

To investigate the relationship between the S100P and the sensitivity of ovarian cancer to chemotherapeutics.

METHOD

We established stable cell lines of ovarian cancer cells, SKOV3 and OVCAR3, that overexpress human S100P. We also transiently transfected the parent cell lines with S100P-targeted siRNA for down-regulation of S100P expression. The sensitivity of all transfected and untransfected cell lines to carboplatin and paclitaxel was detected by MTT assay.

RESULTS

For both cells, IC50s decreased to carboplatin and paclitaxel (p<0.05), with overexpression of S100P compared to untransfected cells. Alternatively, with down-regulation of S100P by siRNA, the IC50 to carboplatin and paclitaxel increased in each case (p<0.05), which was significantly higher compared to untransfected cells.

CONCLUSION

Changes in expression levels of S100P in SKOV3 and OVCAR3 cells results in variable susceptibility to carboplatin and paclitaxel. These data suggest that S100P contributes to chemosensitivity to carboplatin and paclitaxel in ovarian cancer cells.