Aberrant activation of a latent embryonic program - known as the epithelial-mesenchymal transition (EMT) - can endow cancer cells with the migratory and invasive capabilities associated with metastatic competence. The induction of EMT entails the loss of epithelial characteristics and the de novo acquisition of a mesenchymal phenotype. In breast cancer, the EMT state has been associated with cancer stem cell properties including expression of the stem cell-associated CD44+/CD24-/low antigenic profile, self-renewal capabilities and resistance to conventional therapies. Intriguingly, EMT features are also associated with stem cells isolated from the normal mouse mammary gland and human breast reduction tissues as well as the highly aggressive metaplastic and claudin-low breast tumor subtypes. This has implications for the origin of these breast tumors as it remains unclear whether they derive from cells that have undergone EMT or whether they represent an expansion of a pre-existing stem cell population that expresses EMT-associated markers to begin with. In the present review, we consider the current evidence connecting EMT and stem cell attributes and discuss the ramifications of these newly recognized links for our understanding of the emergence of distinct breast cancer subtypes and breast cancer progression.

Background Radiation-associated angiosarcoma (RAAS) is a devastating disease occasionally observed in breast cancer patients treated with radiation. Due to its rarity, our knowledge—of disease risk factors, epidemiology, treatment, and outcome—is extremely limited. Therefore, we sought to identify clinicopathologic factors associated with local and distant recurrence, and disease-specific survival (DSS). Methods Radiation-associated angiosarcoma was defined as pathologically confirmed breast or chest wall angiosarcoma arising within a previously irradiated field. A comprehensive search of our institutional tumor registry (1/1/93 through 2/28/11) was used to identify patients (n=95 females); patient, original tumor, RAAS treatment, and outcome variables were retrospectively retrieved and assembled into a database. Results The median follow-up for all RAAS patients was 10.3 years (range, 2.4 – 31.8 years). The latency period following radiation exposure ranged from 1.4 to 26 years (median = 7 years). One- and five-year DSS rates were 93.5% and 62.6%, respectively. Reduced risk of local recurrence was observed in patients who received chemotherapy (P = 0.0003). In multivariable analysis, size was found to be an independent predictor of adverse outcome (P = 0.015). Discussion Our study demonstrates that RAAS exhibits high recurrence rates. It also highlights the need for well-designed multicenter clinical trials to inform the true utility of chemotherapy in this disease.

Background Radiation therapy is used increasingly as a component of multidisciplinary treatment for many solid tumors. One complication of such treatment is the development of radiation-associated sarcoma (RAS). Undifferentiated pleomorphic sarcoma (UPS), previously termed “malignant fibrous histiocytoma” (MFH) is the most common histologic subtype of RAS. This study investigated the clinical outcomes for patients with radiation-associated UPS (RA-UPS/MFH). Methods The study identified 1068 patients with UPS/MFH treated at the authors’ institution. Patient and tumor factors were collected and compared. Regression analysis was performed to identify independent predictors of survival. A matched-cohort survival and recurrence analysis was performed for radiation-associated and sporadic UPS/MFH. Results The findings showed that RA-UPS/MFH comprised 5.1 % of the UPS population. The median latency to the development of RA-UPS/MFH was 9.3 years. The 5-year disease-specific survival (DSS) was 52.2 % for patients identified with RA-UPS/MFH (n = 55) compared with 76.4 % for patients with unmatched sporadic UPS/MFH (n = 1,013; p < 0.001). A matched-cohort analysis also demonstrated that the 5-year DSS was significantly worse for RA-UPS/MFH (52.2 vs 73.4 %; p = 0.002). Furthermore, higher local recurrence rates were observed for patients with RA-UPS/MFH than for patients with sporadic lesions (54.5 vs 23.5 %; p < 0.001). Radiation-associated status and incomplete resection were identified as independent predictors of local recurrence. Conclusion This study demonstrated worse clinical outcomes for patients with RA-UPS/MFH than for patients with sporadic UPS/MFH. Local recurrence was significantly higher for patients with RA-UPS/MFH, suggesting a unique tumor biology for this challenging disease.

In budding yeast, the eukaryotic initiator protein ORC (origin recognition complex) binds to a bipartite sequence consisting of an 11 bp ACS element and an adjacent B1 element. However, the genome contains many more matches to this consensus than actually bind ORC or function as origins in vivo. Although ORC-dependent loading of the replicative MCM helicase at origins is enhanced by a distal B2 element, less is known about this element. Here, we analyzed four highly active origins (ARS309, ARS319, ARS606 and ARS607) by linker scanning mutagenesis and found that sequences adjacent to the ACS contributed substantially to origin activity and ORC binding. Using the sequences of four additional B2 elements we generated a B2 multiple sequence alignment and identified a shared, degenerate 8 bp sequence that was enriched within 228 known origins. In addition, our high-resolution analysis revealed that not all origins exist within nucleosome free regions: a class of Sir2-regulated origins has a stably positioned nucleosome overlapping or near B2. This study illustrates the conserved yet flexible nature of yeast origin architecture to promote ORC binding and origin activity, and helps explain why a strong match to the ORC binding site is insufficient to identify origins within the genome.

Background Undifferentiated pleomorphic sarcomas (UPS) present a diagnostic and therapeutic challenge. Identification of prognostic molecular markers is required for the discovery of novel treatment approaches. The aim of this study was to correlate clinicopathologic variables, expression of tyrosine kinase receptors, and markers of cell cycle progression and survival with oncologic outcomes. Methods A tissue microarray containing 208 primary UPS samples was analyzed by immunohistochemistry for protein markers and in situ hybridization for microRNA. Staining results were correlated with clinicopathologic features and oncologic outcomes. Univariate and multivariate analyses were conducted to assess associations between expression of protein markers, mi-RNA and outcome. Results At a median follow-up of 3.9 years (9 years for survivors), 5-year disease-specific survival (DSS) was 63%. Clinical variables associated with improved DSS included age < 61 years, tumor size < 10 cm, margin-negative resection and sporadic-tumor status. At the protein level, loss of cyclin D1 (p=0.06), pEGFR (p=0.023), pIGF-1R (p=0.022), and PTEN (p<0.001) and overexpression of AXL (p=0.015) were associated with reduced DSS on univariate analysis. Ki67, PCNA and pEGFR were more highly expressed in sporadic UPS than radiation-associated (RA-UPS) while RA-UPS samples expressed higher levels of both phosphorylated and total IGF-1R. Discussion Cyclin D1, AXL and PTEN are associated with cancer-specific outcomes and warrant further investigation in UPS. The differences in protein expression in sporadic versus RA-UPS may indicate that the activated molecular signaling nodes may be different for each specific histology and could also explain the aggressive phenotype seen in RA-UPS when compared to the sporadic lesions.

Importance Vascular leiomyosarcomas (vLMS) are a rare subtype of leiomyosarcomas (LMS) most commonly affecting the inferior vena cava and accounting for 5% of all LMS. These tumors are aggressive malignancies for which adjuvant modalities have not shown increased efficacy compared over surgery. Our study evaluates potential molecular markers that should be evaluated in prospective studies to determine their prognostic and therapeutic utility. Objective To evaluate the outcomes of patients with vLMS and associations with immunohistochemical prognostic markers. Design Retrospective chart review Setting Single institution Participants A cohort of 77 patients that presented to MDACC from 1993–2012 was analyzed. All of the cases had a confirmed diagnosis of vascular leiomyosarcoma. Immunohistochemical studies for biomarkers were performed on a tissue microarray that included 26 primary vLMS specimens. Main Outcomes and Measures Demographic, and clinical factors were evaluated to assess clinical course, patterns of recurrence and survival outcomes for patients with primary vLMS. Univariate Cox proportional hazards model was utilized to correlate DSS and time to recurrence with potential prognostic indicators. Results Five year disease-specific survival (DSS) rates after tumor resection was 65%. Median time to local recurrence was 43 months, versus 25 months for distant recurrence versus 15 months for concurrent local and distant recurrences; p=0.04. Strong cytoplasmic β-catenin (p=0.06) and IGF-1R (p=0.04) expression were associated with inferior DSS. Conclusions and Relevance vLMS are aggressive malignancies, with high recurrence rates. Expression of β-catenin and IGF-1R were associated with poor DSS. Prospective studies should evaluate their clinical and therapeutic utility.

Undifferentiated pleomorphic sarcomas (UPSs) are aggressive mesenchymal malignancies with no definitive cell of origin or specific recurrent genetic hallmarks. These tumors are largely chemoresistant; thus, identification of potential therapeutic targets is necessary to improve patient outcome. Previous studies demonstrated that high expression of activated protein kinase B (AKT) in patients with UPS corresponds to poor disease-specific survival. Here, we demonstrate that inhibiting phosphatidylinositol-3-kinase/mammalian target of rapamycin (PI3K/mTOR) signaling using a small molecule inhibitor reduced UPS cell proliferation and motility and xenograft growth; however, increased phosphorylation of insulin-like growth factor 1 receptor (IGF1R) indicated the potential for adaptive resistance following treatment through compensatory receptor activation. Co-treatment with a dual PI3K/mTOR inhibitor and an anti-IGF1R kinase inhibitor reduced in vivo tumor growth rates despite a lack of antiproliferative effects in vitro. Moreover, this combination treatment significantly decreased UPS cell migration and invasion, which is linked to changes in p27 subcellular localization. Our results demonstrate that targeted inhibition of multiple components of the IGF1R/PI3K/mTOR pathway was more efficacious than single-agent therapy and suggest that co-targeting this pathway could be a beneficial therapeutic strategy for patients with UPS.

BackgroundAXL is a well-characterized, protumorigenic receptor tyrosine kinase that is highly expressed and activated in numerous human carcinomas and sarcomas, including aggressive subtypes of liposarcoma. However, the role of AXL in the pathogenesis of well-differentiated (WDLPS), dedifferentiated (DDLPS), and pleomorphic liposarcoma (PLS) has not yet been determined.MethodsImmunohistochemical analysis of AXL expression was conducted on two tissue microarrays containing patient WDLPS, DDLPS, and PLS samples. A panel of DDLPS and PLS cell lines were interrogated via western blot for AXL expression and activity and by ELISA for growth arrest-specific 6 (GAS6) production. AXL knockdown was achieved by siRNA or shRNA. The effects of AXL knockdown on cell proliferation, migration, and invasion were measured in vitro. In addition, AXL shRNA-containing DDLPS cells were assessed for their tumor-forming capacity in vivo.ResultsIn this study, we determined that AXL is expressed in a subset of WDLPS, DDLPS, and PLS patient tumor samples. In addition, AXL and its ligand GAS6 are expressed in a panel of DDLPS and PLS cell lines. We show that the in vitro activation of AXL via stimulation with exogenous GAS6 resulted in a significant increase in cell proliferation, migration, and invasion in DDLPS and PLS cell lines. Transient knockdown of AXL resulted in attenuation of these protumorigenic phenotypes in vitro. Stable AXL knockdown not only decreased migratory and invasive characteristics of DDLPS and PLS cells in vitro but also significantly diminished tumorigenicity of two dedifferentiated liposarcoma xenograft models in vivo.ConclusionsOur results suggest that AXL signaling contributes to the aggressiveness of DDLPS and PLS, and that AXL is therefore a potential therapeutic target for treatment of these rare, yet devastating tumors.