Cellular kinetics of MED12-mutant uterine leiomyoma growth and regression in vivo.

Cellular mechanisms of uterine leiomyoma (LM) formation have been studied primarily utilizing in vitro models. However, recent studies established that the cells growing in the primary cultures of MED12-mutant LM (MED12-LM) do not carry causal mutations. To improve the accuracy of LM research, we addressed the cellular mechanisms of LM growth and regression utilizing a patient-derived xenograft (PDX) model, which faithfully replicates the patient tumors in situ The growth and maintenance of MED12-LMs depend on 17ß-estradiol (E2) and progesterone (P4). We determined E2 and P4-activated MAPK and PI3K pathways in PDXs with upregulation of IGF1 and IGF2, suggesting that the hormone actions on MED12-LM are mediated by the IGF pathway. When hormones were removed, MED12-LM PDXs lost approximately 60% of volume within 3 days through reduction in cell size. However, in contrast to general belief, the survival of LM cells was independent of E2 and/or P4, and apoptosis was not involved in the tumor regression. Furthermore, it was postulated that abnormal collagen fibers promote the growth of LMs. However, collagen fibers of actively growing PDXs were well aligned. The disruption of collagen fibers, as found in human LM specimens, occurred only when the volume of PDXs had grown to over 20 times the volume of unstimulated PDXs, indicating disruption is the result of growth not the cause. Hence, this study revises generally accepted theories on the growth and regression of LMs.

Subtype-Specific Tumor-Associated Fibroblasts Contribute to the Pathogenesis of Uterine Leiomyoma.

Recent genomic studies have identified subtypes of uterine leiomyoma (LM) with distinctive genetic alterations. Here, we report the elucidation of the biological characteristics of the two most prevalent uterine leiomyoma subtypes, MED12-mutant (MED12-LM) and HMGA2-overexpressing (HMGA2-LM) uterine leiomyomas. Because each tumor carries only one genetic alteration, both subtypes are considered to be monoclonal. Approximately 90% of cells in HMGA2-uterine leiomyoma were smooth muscle cells (SMC) with HMGA2 overexpression. In contrast, MED12-LM consisted of similar numbers of SMC and non-SMC, which were mostly tumor-associated fibroblasts (TAF). Paradoxically, TAF carried no mutations in MED12, suggesting an interaction between SMC and TAF to coordinate their growth. The higher amount of extracellular matrix in MED12-LM than HMGA2-LM was partially due to the high concentration of collagen-producing TAF. SMC growth in a xenograft assay was driven by progesterone in both uterine leiomyoma subtypes. In contrast, TAF in MED12-LM proliferated in response to estradiol, whereas progesterone had no effect. The high concentration of estrogen-responsive TAF in MED12-LM explains the inconsistent discoveries between in vivo and in vitro studies on the mitogenic effect of estrogen and raises questions regarding the accuracy of previous studies utilizing MED12-LM cell culture. In addition, the differential effects of estradiol and progesterone on these uterine leiomyoma subtypes emphasize the importance of subtypes and genotypes in designing nonsurgical therapeutic strategies for uterine leiomyoma. Cancer Res; 77(24); 6891-901. ©2017 AACR.

Image states at the interface with a dipolar organic semiconductor.

Image states of the dipolar organic semiconductor vanadyl naphthalocyanine on highly oriented pyrolytic graphite are investigated in the submonolayer to few monolayer regime. The presence of a significant molecular dipole in the organized thin films leads to a strong modification of the image states with coverage. In the 0-1 ML regime, we observe successive stabilization of the image state with increasing coverage. Above 1 ML, a new image state develops, corresponding to the screened interaction at the organic semiconductor/substrate interface. We show that the evolution of the observed image states can be understood on the basis of resonance-enhanced anion formation in the presence of strong electric fields. These data represent a step toward understanding the influence of electrostatic fields on electronic structure at organic semiconductor interfaces.

Confocal single molecule fluorescence spectroscopy in ultrahigh vacuum.

We have constructed an ultrahigh vacuum confocal fluorescence microscope with the purpose of performing single molecule spectroscopy under highly defined conditions. The microscope is designed for high stability while affording the capability of sample preparation, sample transfer, and optical detection in ultrahigh vacuum. It achieves near-diffraction-limited performance and allows the observation of single molecule fluorescence dynamics over extended periods of time. The design of the microscope is discussed in detail and the performance is demonstrated with single molecule fluorescence images and trajectories of N,N'-dibutylperylene-3,4,9,10-dicarboxyimide deposited onto several different surfaces. This instrument further enhances the array of available surface science techniques, permitting spectroscopic investigations of molecule-surface interactions at the single molecule level and on insulating surfaces.

Single molecule power-law behavior on a crystalline surface.

Single perylene bisimide molecules deposited onto Al(2)O(3) (0001) and investigated under controlled ultrahigh vacuum conditions display fluorescence intermittency behavior characteristic of an interfacial charge transfer process. Remarkably, even though the molecules are deposited on a crystalline surface with reduced disorder, power-law-distributed bright and dark periods are observed. These data can be understood based on activated formation of localized small polaron states in Al(2)O(3) (0001). We present a kinetic scheme capable of explaining the occurrence of power-law distributions for both "on" and "off" periods for single molecules on the sapphire substrate. These findings represent a first step toward understanding interfacial charge transfer processes under controlled conditions on crystalline surfaces and at the single molecule level.