Over the past 60 years, investigators of basic science, pathology, and clinical medicine have studied gastrointestinal stromal tumor (GIST) and made minor advances in patient care. Recent discoveries have led to an understanding of the biological role of KIT and platelet-derived growth factor receptor-α in GIST and the development of the tyrosine kinase inhibitor imatinib mesylate (Gleevec, formerly STI-571), one of the most exciting examples of targeted therapy to date. The success of targeted therapy in GIST has lead to new developments in our understanding of the medical and surgical management of the disease. Intense study of GIST may lead to new paradigms in the management of cancer.
Antineoplastic Agents ; therapeutic use ; Benzamides ; Combined Modality Therapy ; Drug Delivery Systems ; Gastrointestinal Neoplasms ; drug therapy ; genetics ; pathology ; surgery ; Gastrointestinal Stromal Tumors ; drug therapy ; genetics ; pathology ; surgery ; Humans ; Imatinib Mesylate ; Mutation ; Piperazines ; therapeutic use ; Protein Kinase Inhibitors ; therapeutic use ; Proto-Oncogene Proteins c-kit ; genetics ; metabolism ; Pyrimidines ; therapeutic use ; Receptor, Platelet-Derived Growth Factor alpha ; genetics ; metabolism

The phosphatidylinositol-3 kinase(PI3K) pathway regulates a number of cellular processes, including cell survival, cell growth, and cell cycle progression. Consequently, this pathway is commonly deregulated in cancer. In particular, mutations in the gene PIK3CA that encodes the p110α catalytic subunit of the PI3K enzymes result in cell proliferation and resistance to apoptosis in vitro and induce breast tumors in transgenic mice. These data underscore the role of this pathway during oncogenesis. Thus, an ongoing, large-scale effort is underway to develop clinically active drugs that target elements of the PI3K pathway. However, conflicting data suggest that gain-of-function PIK3CA mutations may be associated with either a favorable or a poor clinical outcome, compared with the wild-type PIK3CA gene. In the current study, we performed a systematic review of breast cancer clinical studies. Upon evaluation of 2587 breast cancer cases from 12 independent studies, we showed that patients with tumors harboring a PIK3CA mutation have a better clinical outcome than those with a wild-type PIK3CA gene. Importantly, this improved prognosis may pertain only to patients with mutations in the kinase domain of p110α and to postmenopausal women with estrogen receptor-positive breast cancer. We propose three potential explanations for this paradoxical observation. First, PIK3CA mutations may interfere with the metastasis process or may induce senescence, which results in a better outcome for patients with mutated tumors. Secondly, we speculate that PIK3CA mutations may increase early tumor diagnosis by modification of the actin cytoskeleton in tumor cells. Lastly, we propose that PIK3CA mutations may be a favorable predictive factor for response to hormonal therapy, giving a therapeutic advantage to these patients. Ultimately, an improved understanding of the clinical impact of PIK3CA mutations is critical for the development of optimally personalized therapeutics against breast cancer and other solid tumors. This effort will be important to prevent or explain therapeutic failures and select patients who are most likely to respond to new therapies that inhibit the PI3K pathway.
Antineoplastic Agents, Hormonal ; therapeutic use ; Apoptosis ; Breast Neoplasms ; drug therapy ; genetics ; metabolism ; pathology ; Cellular Senescence ; Class I Phosphatidylinositol 3-Kinases ; Disease-Free Survival ; Early Detection of Cancer ; Female ; Humans ; Mutation ; Neoplasm Metastasis ; Phosphatidylinositol 3-Kinases ; antagonists & inhibitors ; genetics ; metabolism ; Survival Rate

OBJECTIVEOur previous study shows that PURNE2 mRNA plays an important role in the differential diagnosis of leiomyosarcoma and gastrointestinal stromal tumor (GIST). Non-coding RNA PCA3 locates in the intron of PRUNE2 and may play a role in PRUNE2 expression. The aim of this study was to explore the expression of PCA3 mRNA and PRUNE2 in leiomyosarcoma and their correlation.

METHODSThe expression of PRUNE2 mRNA was analyzed by agilent gene expression microarray CHIP in 31 leiomyosarcomas and 37 GISTs, and the correlation of the PRUNE2 expression and prognosis of leiomyosarcoma was predicted. Real-Time PCR assay was used to detect the mRNA levels of PCA3 and PRUNE2 in 13 leiomyosarcomas and to investigate their correlation. Seven prostate cancer tissues were used as control of PCA3.

RESULTSThe level of PRUNE2 mRNA expression was significantly higher in the 31 leiomyosarcomas than that in the 37 GISTs, and the level of PRUNE2 mRNA expression was correlated with survival of the leiomyosarcoma patients. Compared with prostate cancer, the non-coding RNA PCA3 expression level was significantly lower in leiomyosarcoma, and it had no correlation with the prognosis of leiomyosarcoma. Most importantly, the PRUNE2 and PCA3 mRNA expressions were both upregulated in leiomyosarcoma and showed a significant positive correlation.

CONCLUSIONSOur findings demonstrate for the first time that PRUNE2 expression is correlated with the survival of leiomyosarcoma patients. Furthermore, non-coding RNA PCA3, which locates in the intron of PRUNE2, has a significant positive correlation with PRUNE2 and may play an important role in the pathogenesis of leiomyosarcoma.

Antigens, Neoplasm ; genetics ; metabolism ; Female ; Gastrointestinal Neoplasms ; genetics ; metabolism ; Gastrointestinal Stromal Tumors ; genetics ; metabolism ; Humans ; Leiomyosarcoma ; genetics ; metabolism ; Male ; Neoplasm Proteins ; genetics ; metabolism ; Prostatic Neoplasms ; genetics ; metabolism ; RNA, Messenger ; metabolism ; RNA, Untranslated ; metabolism ; Retroperitoneal Neoplasms ; genetics ; metabolism ; Survival Rate ; Uterine Neoplasms ; genetics ; metabolism