Faculty Bibliography

OBJECTIVE: To evaluate the role of senescence in symptomatic patients with multifibroids. DESIGN: A cohort study. SETTING: University research laboratory. PATIENT(S): Eighty-six fibroids collected from 14 patients who underwent myomectomy or hysterectomy. INTERVENTION(S): Senescence-associated beta-galactosidase (SA-beta-Gal) stain in fresh-frozen tissue; reverse-transcription polymerase chain reaction (RT-PCR); MicroRNA in situ hybridization (MISH); immunohistochemistry in formalin-fixed paraffin-embedded tissue. MAIN OUTCOME MEASURE(S): Senescence measured by percentage of SA-beta-Gal-positive cells; levels of let-7 microRNAs measured by RT-PCR and MISH; expression of p16(INK4a), Ki-67, HMGA1, and HMGA2 scaled by immunoreactivity. RESULT(S): About 58% (48 of 82) of tumors showed significant senescent change (SA-beta-Gal positive) in >10% of the tumor volume. The overall trend was a higher level of senescence in small fibroids and older-aged women. Senescent fibroids were additionally shown to have, high levels of let-7 c, d, and f-2 and a low Ki-67 index. CONCLUSION(S): Senescence is a common cellular change in a large proportion of usual type fibroids. Similarly, senescence may explain the variation in growth rates of these tumors, and may prove to be an important molecular and cellular target in prevention of fibroid growth

BACKGROUND: Human uterine leiomyomas (ULM) are characterized by dysregulation of a large number of genes and non-coding regulatory microRNAs. In order to identify microRNA::mRNA associations relevant to ULM pathogenesis, we examined global correlation patterns between the altered microRNA expression and the predicted target genes in ULMs and matched myometria. METHODOLOGY/PRINCIPAL FINDINGS: Patterns of inverse association of microRNA with mRNA expression in ULMs revealed an involvement of multiple candidate pathways, including extensive transcriptional reprogramming, cell proliferation control, MAP kinase, TGF-beta, WNT, JAK/STAT signaling, remodeling of cell adhesion, and cell-cell and cell-matrix contacts. We further examined the correlation between the expression of the selected target gene protein products and microRNAs in thirty-six paired sets of leiomyomas and matched myometria. We found that a number of dysregulated microRNAs were inversely correlated with their targets at the protein level. The comparative genomic hybridization (CGH) in eight ULM patients revealed that partially shared deletions of two distinct chromosomal regions might be responsible for loss of cancer-associated microRNA expression and could thus contribute to the ULM pathogenesis via deregulation of target mRNAs. Last, we functionally tested the repressor effects of selected cancer-related microRNAs on their predicted target genes in vitro. CONCLUSIONS/SIGNIFICANCE: We found that some but not all of the predicted and inversely correlated target genes in ULMs can be directly regulated by microRNAs in vitro. Our findings provide a broad overview of molecular events underlying the tumorigenesis of uterine ULMs and identify select genetic and regulatory events that alter microRNA expression and may play important roles in ULM pathobiology by positively regulating tumor growth while maintaining the non-invasive character of ULMs

Before high-grade papillary serous carcinoma (HG-PSC) becomes invasive, it is believed to be a poorly defined short-lived precursor lesion. A recent characterization of serous tubal intraepithelial carcinoma (STIC) and of the p53 signature suggested that HG-PSC may follow a stepwise progression on cellular and molecular levels. High-mobility group AT-hook 2 (HMGA2), an oncofetal protein, is overexpressed in ovarian cancer. To test whether HMGA2 can be another valuable marker for STIC, we examined HMGA2 expression in 3 groups of patients: (1) 24 patients with STIC and its invasive counterpart, HG-PSC of the fallopian tubes, (2) 24 patients with HG-PSC of the ovaries but without STIC (positive control), and (3) 30 patients with cancer and normal fallopian tubes (negative control). We found that HMGA2 was overexpressed in 75% of patients with STIC, was coexpressed with p53 in more than 50% of patients, and was completely negative in the secretory cells of the 30 patients with normal fallopian tubes. Among 7 patients with cells negative for p53 staining, HMGA2 was positive in 5; among 6 patients whose tumor cells were negative for HMGA2 in STIC, 3 were positive for HMGA2 in the invasive component; about 70% of invasive HG-PSC tumor cells were immunoreactive for both HMGA2 and TP53. In invasive carcinoma, HMGA2 overexpression was correlated with p53 (r=0.45), indicating the role of HMGA2 in p53 mediated tumor progression. Our findings of immunoreactivity for HMGA2 may lead to a novel, useful biomarker to complement p53 in the detection of early-stage serous carcinoma

Androgen receptor (AR), a member of the steroid receptor family, is a transcription factor that has an important role in the regulation of both prostate cell proliferation and growth suppression. AR coactivators may influence the transition between cell growth and growth suppression. We have shown previously that the internally spliced ARA70 isoform, ARA70beta, promotes prostate cancer cell growth and invasion. Here we report that the full length ARA70alpha, in contrast, represses prostate cancer cell proliferation and anchorage-independent growth in vitro and inhibits tumor growth in nude mice xenograft experiments in vivo. Further, the growth inhibition by ARA70alpha is AR-dependent and mediated through induction of apoptosis rather than cell cycle arrest. Interestingly, AR with T877A mutation in LNCaP cells decreased its physical and functional interaction with ARA70alpha, facilitating the growth of LNCaP cells. This is consistent with our previous findings that ARA70alpha expression is decreased in prostate cancer cells compared with benign prostate. ARA70alpha also reduced the invasion ability of LNCaP cells. Although growth inhibition by ARA70alpha is AR-dependent, the inhibition of cell invasion is an androgen-independent process. These results strongly suggest that ARA70alpha functions as a tumor suppressor gene

Previous studies have shown that key enzymes involved in lipid metabolic pathways are differentially expressed in normal compared with tumor tissues. However, the precise role played by dysregulated expression of lipid metabolic enzymes and altered lipid homeostasis in carcinogenesis remains to be established. Fatty acid synthase is overexpressed in a variety of cancers, including breast and prostate. The purpose of the present study was to examine the expression patterns of additional lipid metabolic enzymes in human breast and prostate cancers. This was accomplished by analysis of published expression databases, with confirmation by immunoblot assays. Our results indicate that the fatty acid-activating enzyme, long-chain fatty acyl-CoA synthetase 4 (ACSL4), is differentially expressed in human breast cancer as a function of estrogen receptor alpha (ER) status. In 10 separate studies, ACSL4 messenger RNA (mRNA) was overexpressed in ER-negative breast tumors. Of 50 breast cancer cell lines examined, 17 (89%) of 19 ER-positive lines were negative for ACSL4 mRNA expression and 20 (65%) of 31 ER-negative lines expressed ACSL4 mRNA. The inverse relationship between ER expression and ACSL4 expression was also observed for androgen receptor status in both breast and prostate cancers. Furthermore, loss of steroid hormone sensitivity, such as that observed in Raf1-transfected MCF-7 cells and LNCaP-AI cells, was associated with induction of ACSL4 expression. Ablation of ACSL4 expression inMDA-MB-231 breast cancer cells had no effect on cell proliferation; however, sensitivity to the cytotoxic effects of triacsin C was increased three-fold in the cells lacking ACSL4

Ovarian carcinoma consists of a group of histologically heterogeneous diseases involving distinct tumorigenic pathways. High-grade papillary serous carcinoma of the ovary is commonly associated with p53 mutations. HMGA2, an oncofetal protein, is found to be overexpressed in ovarian cancer. To study the function of HMGA2 in ovarian cancer, it is important to know which subtypes of ovarian cancer are associated with HMGA2 overexpression. In this study, we collected six different types of ovarian cancer and examined HMGA2 expression by immunohistochemistry, along with HMGA1, p53 and Ki-67. We found that HMGA2 overexpression was significantly higher in high-grade papillary serous carcinoma (64%) and carcinosarcoma (60%) than in other types of ovarian cancers (7-23%). HMGA2 overexpression was moderately associated with dominant p53 mutations (R=0.51). In addition, the microRNA in situ analysis revealed that let-7b, the HMGA2-negative regulators, were significantly lost in high-grade serous carcinoma. Our findings suggest that HMGA2 is an important molecular change significantly related to high-grade papillary serous carcinoma and is less common in other histological types of ovarian cancer.Modern Pathology advance online publication, 12 March 2010; doi:10.1038/modpathol.2010.49

Sarcomas are a heterogeneous group of tumors that are traditionally classified according to the morphology and type of tissue that they resemble, such as rhabdomyosarcoma, which resembles skeletal muscle. However, the cell of origin is unclear in numerous sarcomas. Molecular genetics analyses have not only assisted in understanding the molecular mechanism in sarcoma pathogenesis but also demonstrated new relationships within different types of sarcomas leading to a more proper classification of sarcomas. Molecular classification based on the genetic alteration divides sarcomas into two main categories: (i) sarcomas with specific genetic alterations; which can further be subclassified based on a) reciprocal translocations resulting in oncogenic fusion transcripts (e.g. EWSR1-FLI1 in Ewing sarcoma) and b) specific oncogenic mutations (e.g. KIT and PDGFRA mutations in gastrointestinal stromal tumors) and (ii) sarcomas displaying multiple, complex karyotypic abnormalities with no specific pattern, including leiomyo-sarcoma, and pleomorphic liposarcoma. These specific genetic alterations are an important adjunct to standard morphological and immunohistochemical diagnoses, and in some cases have a prognostic value, e. g., Ewing family tumors, synovial sarcoma, and alveolar rhabdomyosarcoma. In addition, these studies may also serve as markers to detect minimal residual disease and can aid in staging or monitor the efficacy of therapy. Furthermore, sarcoma-specific fusion genes and other emerging molecular events may also represent potential targets for novel therapeutic approaches such as Gleevec for dermatofibrosarcoma protuberans. Therefore, increased understanding of the molecular biology of sarcomas is leading towards development of newer and more effective treatment regimens. The review focuses on recent advances in molecular genetic alterations having an impact on diagnostics, prognostication and clinical management of selected sarcomas