Xiaoling Du

Genetic aberrations of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm in the gastrointestinal tract and is associated with mutations of the KIT or PDGFRA gene. In addition, other genetic events are believed to be involved in GIST tumorigenesis. Cytogenetic aberrations associated with these tumors thus far described include loss of 1p, 13q, 14q, or 15q, loss of heterozygosity of 22q, numeric chromosomal imbalances, and nuclear/mitochondrial microsatellite instability. Molecular genetic aberrations include loss of heterozygosity of p16(INK4A) and p14(ARF), methylation of p15(INK4B), homozygous loss of the Hox11L1 gene, and amplification of C‐MYC, MDM2, EGFR1, and CCND1. GISTs in patients with neurofibromatosis type 1 appear to lack the KIT and PDGFRA mutations characteristic of GISTs and may have a different pathogenetic mechanism. Gene mutations of KIT or PDGFRA are critical in GISTs, because the aberrant versions not only are correlated with the specific cell morphology, histologic phenotype, metastasis, and prognosis, but also are the targets of therapy with imatinib and other agents. Furthermore, specific mutations in KIT and PDGFR appear to lead to differential drug sensitivity and may in the future guide selection of tyrosine kinase inhibitors. Activation of the receptor tyrosine kinases involves a signal transduction pathway whose components (mitogen‐activated protein kinase, AKT, phosphoinositide 3‐kinase, mammalian target of rapamycin, and RAS) are also possible targets of inhibition. A new paradigm of classification, integrating the standard clinical and pathological criteria with molecular aberrations, may permit personalized prognosis and treatment. Cancer 2008.

Genetic Aberrations in Soft Tissue Leiomyosarcoma

Leiomyosarcoma is a malignant mesenchymal tumor composed of cells showing smooth muscle differentiation. This tumor usually occurs in middle-aged or older adults, and forms a significant percentage of retroperitoneal, vascular, extremity, and uterine sarcomas. Leiomyosarcomas are most often associated with complex karyotypes with numerous chromosomal gains and losses. Some of these cytogenetic and molecular genetic aberrations correlate with histopathologic features and clinical outcomes. Identification of genetic alterations with specific identification of oncogenes and tumor suppressor genes may lead to additional insights into the tumorigenesis of leiomyosarcoma and the opportunity to confer the benefits of targeted therapy.

Deletion of the WWOX gene and frequent loss of its protein expression in human osteosarcoma

To evaluate the role of WWOX gene in human osteosarcoma, array comparative genomic hybridization on 10 frozen osteosarcoma specimens and immunohistochemical staining of 55 formalin-fixed and paraffin-embedded tissues for WWOX was performed. Deletion of the WWOX gene was observed in 3 of 10 samples and the WWOX protein was undetectable in 34 of 55 osteosarcomas. This is the first investigation of the role of WWOX gene in human osteosarcoma. The WWOX gene deletion, loss of its protein expression, and lack of correlation of WWOX expression with patient survival suggest loss of WWOX expression is an early event in the pathogenesis of osteosarcoma and the phenotypic results of its deletion do not imminently result in patient death.

Advances in targeted therapy for unresectable melanoma: New drugs and combinations

Melanoma is the most deadly cutaneous cancer primarily derived from melanocytes with a poor prognosis in advanced stage. The therapy regimen for early stage melanoma patients is surgical resection with adjuvant IFN-alpha-2b therapy. For metastatic lesions, standard chemotherapy such as dacarbazine (DTIC) has not achieved a satisfying response rate. Therefore, new approaches to manage this deadly disease are highly expected to enhance the cure rate and to extend clinical benefits to patients with unresectable melanoma. Fortunately, the targeted therapeutic drugs and immunotherapy such as vemurafenib, dabrafenib, ipilimumab, and trametinib have shown their special advantage in the treatment of advanced melanoma. This article is to overview the advances in targeted therapy for unresectable melanoma patients.

APEX1 gene amplification and its protein overexpression in osteosarcoma: Correlation with recurrence, metastasis, and survival

The expression of apurinic/apyrimidinic exonuclease 1 (APEX1) in tumors has been linked with chemoresistance, radioresistance, and shorter patient survival times. We sought to gain insight into the role of APEX1 in human osteosarcoma by evaluation of gene copy number alterations and its protein expression in osteosarcoma patients treated at the Sarcoma Center of Tianjin Cancer Hospital (Tianjin, China). To evaluate the gene copy number alterations of APEX1, we acquired 10 fresh tissue samples from 9 patients and performed whole-genome array-based comparative genomic hybridization (aCGH). We next acquired formalin-fixed and paraffin embedded tissues from 57 well-annotated osteosarcoma cases and performed immunohistochemical analyses for APEX1. APEX1 gene amplification was observed in 50% (5/10) of the osteosarcoma samples. The overexpression of APEX1 protein was detected in 64.9% (37/57) of the osteosarcomas ranging from negative (35.1%, 20/57), weakly positive (35.1%, 20/57), moderate (14%, 8/57) and strongly positive (15.8%, 9/57). The APEX1 expression had significant correlation with osteosarcoma local recurrence and/or metastasis. Moreover, multivariate analysis showed that APEX1 expression was an independent molecular predictor for disease-free survival of patients with osteosarcomas. Our study for the first time showed that APEX1 gene was amplified in osteosarcomas and that APEX1 expression was an independent predictor of the osteosarcoma local recurrence and/or metastasis. Thus, APEX1 may serve as a prognostic marker and potential therapeutic target for osteosarcoma.

Mesenchymal to epithelial transition in sarcomas

Mesenchymal to epithelial transition (MET) in carcinomas has been proposed to promote the growth of epithelial tumour cells at distant sites during metastasis. MET has also been suggested as an important biological and clinical process in mesenchymal tumors, sarcomas. Here we review studies on MET in sarcomas, including molecular markers, signalling mechanisms, regulation by micro RNAs and therapeutic implications. Accumulating evidences suggest that deeper investigation and understanding of MET in sarcomas would shed light on the pathogenesis of sarcomas and might lead to identification of potential clinical biomarkers for prognosis and targets for sarcoma therapeutics.

The genetic basis for inactivation of Wnt pathway in human osteosarcoma

BackgroundOsteosarcoma is a highly genetically unstable tumor with poor prognosis. We performed microarray-based comparative genomic hybridization (aCGH), transcriptome sequencing (RNA-seq), and pathway analysis to gain a systemic view of the pathway alterations of osteosarcoma.MethodsaCGH experiments were carried out on 10 fresh osteosarcoma samples. The output data (Gene Expression Omnibus Series accession number GSE19180) were pooled with published aCGH raw data (GSE9654) to determine recurrent copy number changes. These were analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis to identify altered pathways in osteosarcoma. Transcriptome sequencing of six osteosarcomas was performed to detect the expression profile of Wnt signaling pathway genes. Protein expression of WNT1, β-catenin, c-myc, and cyclin D1 in the Wnt pathway was detected by immunohistochemistry (IHC) in an independent group of 46 osteosarcoma samples.ResultsKEGG pathway analysis identified frequent deletions of Wnt and other Wnt signaling pathway genes. At the mRNA level, transcriptome sequencing found reduced levels of mRNA expression of Wnt signaling pathway transcripts. While WNT1 protein expression was detected by IHC in 69.6% (32/46) of the osteosarcomas, no β-catenin protein was detected in the nucleus. β-catenin protein expression was, however, detected in the membrane and cytoplasm of 69.6% (32/46) of the osteosarcomas. c-myc protein expression was detected in only 47.8% (22/46) and cyclin D1 protein expression in 52.2% (24/46) of osteosarcoma samples. Kaplan-Meier survival analysis showed that WNT1-negative patients had a trend towards longer disease free survival than WNT1-positive patients. Interestingly, in WNT1-negative patients, those who were also cyclin D1-negative had significantly longer disease free survival than cyclin D1-positive patients. However, there was no significant association between any of the investigated proteins and overall survival of human osteosarcoma patients.ConclusionsFrequent deletions of Wnt and other Wnt signaling pathway genes suggest that the Wnt signaling pathway is genetically inactivated in human osteosarcoma.

Genomic amplification and high expression of EGFR are key targetable oncogenic events in malignant peripheral nerve sheath tumor

BackgroundThe dismal outcome of malignant peripheral nerve sheath tumor (MPNST) highlights the necessity of finding new therapeutic methods to benefit patients with this aggressive sarcoma. Our purpose was to investigate epidermal growth factor receptor (EGFR) as a potential therapeutic target in MPNSTs.Patients and methodsWe performed a microarray based-comparative genomic hybridization (aCGH) profiling of two cohorts of primary MPNST tissue samples including 25 patients treated at The University of Texas MD Anderson Cancer Center (MD Anderson) and 26 patients from Tianjin Medical University Cancer Institute & Hospital (TMUCIH). Fluorescence in situ hybridization (FISH) method was used to validate the gene amplification detected by aCGH analysis. Another independent cohort of 56 formalin fixed paraffin embedded (FFPE) MPNST samples was obtained to explore EGFR protein expression by immunohistochemical analysis. Cell biology detection and validation were performed on human MPNST cell lines ST88-14 and STS26T.ResultsaCGH and pathway analysis of the 51 MPNSTs identified significant gene amplification events in EGFR pathway, including frequent amplifications of EGFR gene itself, which was subsequently validated by FISH assay. High expression of EGFR protein was associated with poor disease-free and overall survival of human MPNST patients. In human MPNST cell lines ST88-14 and STS26T, inhibition of EGFR by siRNA or Gefitinib led to decreased cell proliferation, migration, and invasion accompanied by attenuation of PI3K/AKT and MAPK pathways.ConclusionThese results suggest that EGFR is a potential therapeutic target for MPNST.

Recurrent LRP1-SNRNP25 and KCNMB4-CCND3 fusion genes promote tumor cell motility in human osteosarcoma

BackgroundThe identification of fusion genes such as SYT-SSX1/SSX2, PAX3-FOXO1, TPM3/TPM4-ALK and EWS-FLI1 in human sarcomas has provided important insight into the diagnosis and targeted therapy of sarcomas. No recurrent fusion has been reported in human osteosarcoma.MethodsTranscriptome sequencing was used to characterize the gene fusions and mutations in 11 human osteosarcomas.ResultsNine of 11 samples were found to harbor genetic inactivating alterations in the TP53 pathway. Two recurrent fusion genes associated with the 12q locus, LRP1-SNRNP25 and KCNMB4-CCND3, were identified and validated by RT-PCR, Sanger sequencing and fluorescence in situ hybridization, and were found to be osteosarcoma specific in a validation cohort of 240 other sarcomas. Expression of LRP1-SNRNP25 fusion gene promoted SAOS-2 osteosarcoma cell migration and invasion. Expression of KCNMB4-CCND3 fusion gene promoted SAOS-2 cell migration.ConclusionsOur study represents the first whole transcriptome analysis of untreated human osteosarcoma. Our discovery of two osteosarcoma specific fusion genes associated with osteosarcoma cellular motility highlights the heterogeneity of osteosarcoma and provides opportunities for new treatment modalities.

Efficacy and safety of Apatinib in stage IV sarcomas: experience of a major sarcoma center in China

PURPOSE This study was conducted to review the efficacy and safety of Apatinib in stage IV sarcoma patients who failed previous chemotherapy. MATERIALS AND METHODS The clinical information on 16 patients with stage IV sarcomas who failed in prior chemotherapy and subsequently received Apatinib treatment was collected. Apatinib was given 500mg/daily and 4 weeks as a cycle. All patients had at least one measurable extracranial tumor according to Response Evaluation Criteria In Solid Tumors 1.0 criteria. Progression free survival (PFS), overall survival (OS), objective response rate (ORR), disease control rate (DCR) and treatment-related adverse effects (AEs) were reviewed and evaluated. RESULTS Patients was administered Apatinib for 0 to 9 cycles with the median of 3.2 cycles. Median follow-up time was 8.4 months (1 to 12 months). Ten of 16 patients received at least 1 complete cycle of Apatinib treatment were eligible for the efficacy analysis. The median PFS was 8.84 months. Two patients achieved partial response (PR) and 6 patients achieved stable disease (SD). Two patients were evaluated as progression disease (PD) and one patient died of disease progression. The ORR was 20.0% (2/10) and the DCR was 80.0% (8/10). The most common grade 3/4 treatment-related AEs were hypertension (18.7%), hand-foot syndrome (12.5%) and proteinuria (6.3%). No drug-related severe AEs occurred. CONCLUSION Apatinib treatment in this exploratory study exhibited objective efficacy and manageable toxicity in stage IV sarcoma patients who failed in chemotherapy. This result supports future random controlled trial to further define Apatinib activity in stage IV sarcomas.Purpose This study was conducted to review the efficacy and safety of Apatinib in stage IV sarcoma patients who failed previous chemotherapy. Materials and Methods The clinical information on 16 patients with stage IV sarcomas who failed in prior chemotherapy and subsequently received Apatinib treatment was collected. Apatinib was given 500mg/daily and 4 weeks as a cycle. All patients had at least one measurable extracranial tumor according to Response Evaluation Criteria In Solid Tumors 1.0 criteria. Progression free survival (PFS), overall survival (OS), objective response rate (ORR), disease control rate (DCR) and treatment-related adverse effects (AEs) were reviewed and evaluated. Results Patients was administered Apatinib for 0 to 9 cycles with the median of 3.2 cycles. Median follow-up time was 8.4 months (1 to 12 months). Ten of 16 patients received at least 1 complete cycle of Apatinib treatment were eligible for the efficacy analysis. The median PFS was 8.84 months. Two patients achieved partial response (PR) and 6 patients achieved stable disease (SD). Two patients were evaluated as progression disease (PD) and one patient died of disease progression. The ORR was 20.0% (2/10) and the DCR was 80.0% (8/10). The most common grade 3/4 treatment-related AEs were hypertension (18.7%), hand-foot syndrome (12.5%) and proteinuria (6.3%). No drug-related severe AEs occurred. Conclusion CApatinib treatment in this exploratory study exhibited objective efficacy and manageable toxicity in stage IV sarcoma patients who failed in chemotherapy. This result supports future random controlled trial to further define Apatinib activity in stage IV sarcomas.