The Eker Rat: Establishing a Genetic Paradigm Linking Renal Cell Carcinoma and Uterine Leiomyoma

TGFβ signaling links early life endocrine-disrupting chemicals exposure to suppression of nucleotide excision repair in rat myometrial stem cells

Environmental exposure to endocrine-disrupting chemicals (EDCs) is linked to the development of uterine fibroids (UFs) in women. UFs, non-cancerous tumors, are thought to originate from abnormal myometrial stem cells (MMSCs). Defective DNA repair capacity may contribute to the emergence of mutations that promote tumor growth. The multifunctional cytokine TGFβ1 is associated with UF progression and DNA damage repair pathways. To investigate the impact of EDC exposure on TGFβ1 and nucleotide excision repair (NER) pathways, we isolated MMSCs from 5-month-old Eker rats exposed neonatally to diethylstilbestrol (DES), an EDC, or to vehicle (VEH). EDC-MMSCs exhibited overactivated TGFβ1 signaling and reduced mRNA and protein levels of NER pathway components compared to VEH-MMSCs. EDC-MMSCs also demonstrated impaired NER capacity. Exposing VEH-MMSCs to TGFβ1 decreased NER capacity while inhibiting TGFβ signaling in EDC-MMSCs restored it. RNA-seq analysis and further validation revealed decreased expression of Uvrag, a tumor suppressor gene involved in DNA damage recognition, in VEH-MMSCs treated with TGFβ1, but increased expression in EDC-MMSCs after TGFβ signaling inhibition. Overall, we demonstrated that the overactivation of the TGFβ pathway links early life exposure to EDCs with impaired NER capacity, which would lead to increased genetic instability, arise of mutations, and fibroid tumorigenesis. We demonstrated that the overactivation of the TGFβ pathway links early life exposure to EDCs with impaired NER capacity, which would lead to increased fibroid incidence.

TGFβ signaling links early-life endocrine-disrupting chemicals exposure to suppression of nucleotide excision repair in rat myometrial stem cells

Environmental exposure to endocrine-disrupting chemicals (EDCs) is linked to the development of uterine fibroids (UFs) in women. UFs, non-cancerous tumors, are thought to originate from abnormal myometrial stem cells (MMSCs). Defective DNA repair capacity may contribute to the emergence of mutations that promote tumor growth. The multifunctional cytokine TGFβ1 is associated with UF progression and DNA damage repair pathways. To investigate the impact of EDC exposure on TGFβ1 and nucleotide excision repair (NER) pathways, we isolated MMSCs from 5-months old Eker rats exposed neonatally to Diethylstilbestrol (DES), an EDC, or to vehicle (VEH). EDC-MMSCs exhibited overactivated TGFβ1 signaling and reduced mRNA and protein levels of NER pathway components compared to VEH-MMSCs. EDC-MMSCs also demonstrated impaired NER capacity. Exposing VEH-MMSCs to TGFβ1 decreased NER capacity while inhibiting TGFβ signaling in EDC-MMSCs restored it. RNA-seq analysis and further validation revealed decreased expression of Uvrag, a tumor suppressor gene involved in DNA damage recognition, in VEH-MMSCs treated with TGFβ1, but increased expression in EDC-MMSCs after TGFβ signaling inhibition. Overall, we demonstrated that the overactivation of the TGFβ pathway links early-life exposure to EDCs with impaired NER capacity, which would lead to increased genetic instability, arise of mutations, and fibroid tumorigenesis. We demonstrated that the overactivation of the TGFβ pathway links early-life exposure to EDCs with impaired NER capacity, which would lead to increased fibroid incidence.

Research-Relevant Conditions and Pathology of Laboratory Mice, Rats, Gerbils, Guinea Pigs, Hamsters, Naked Mole Rats, and Rabbits

Animals are valuable resources in biomedical research in investigations of biological processes, disease pathogenesis, therapeutic interventions, safety, toxicity, and carcinogenicity. Interpretation of data from animals requires knowledge not only of the processes or diseases (pathophysiology) under study but also recognition of spontaneous conditions and background lesions (pathology) that can influence or confound the study results. Species, strain/stock, sex, age, anatomy, physiology, spontaneous diseases (noninfectious and infectious), and neoplasia impact experimental results and interpretation as well as animal welfare. This review and the references selected aim to provide a pathology resource for researchers, pathologists, and veterinary personnel who strive to achieve research rigor and validity and must understand the spectrum of "normal" and expected conditions to accurately identify research-relevant experimental phenotypes as well as unusual illness, pathology, or other conditions that can compromise studies involving laboratory mice, rats, gerbils, guinea pigs, hamsters, naked mole rats, and rabbits.

Histotripsy Ablation in Preclinical Animal Models of Cancer and Spontaneous Tumors in Veterinary Patients: A Review

New therapeutic strategies are direly needed in the fight against cancer. Over the last decade, several tumor ablation strategies have emerged as stand-alone or combination therapies. Histotripsy is the first completely noninvasive, nonthermal, and nonionizing tumor ablation method. Histotripsy can produce consistent and rapid ablations, even near critical structures. Additional benefits include real-time image guidance, high precision, and the ability to treat tumors of any predetermined size and shape. Unfortunately, the lack of clinically and physiologically relevant preclinical cancer models is often a significant limitation with all focal tumor ablation strategies. The majority of studies testing histotripsy for cancer treatment have focused on small animal models, which have been critical in moving this field forward and will continue to be essential for providing mechanistic insight. While these small animal models have notable translational value, there are significant limitations in terms of scale and anatomical relevance. To address these limitations, a diverse range of large animal models and spontaneous tumor studies in veterinary patients have emerged to complement existing rodent models. These models and veterinary patients are excellent at providing realistic avenues for developing and testing histotripsy devices and techniques designed for future use in human patients. Here, we provide a review of animal models used in preclinical histotripsy studies and compare histotripsy ablation in these models using a series of original case reports across a broad spectrum of preclinical animal models and spontaneous tumors in veterinary patients.

Immunological Effects of Histotripsy for Cancer Therapy

Cancer is the second leading cause of death worldwide despite major advancements in diagnosis and therapy over the past century. One of the most debilitating aspects of cancer is the burden brought on by metastatic disease. Therefore, an ideal treatment protocol would address not only debulking larger primary tumors but also circulating tumor cells and distant metastases. To address this need, the use of immune modulating therapies has become a pillar in the oncology armamentarium. A therapeutic option that has recently emerged is the use of focal ablation therapies that can destroy a tumor through various physical or mechanical mechanisms and release a cellular lysate with the potential to stimulate an immune response. Histotripsy is a non-invasive, non-ionizing, non-thermal, ultrasound guided ablation technology that has shown promise over the past decade as a debulking therapy. As histotripsy therapies have developed, the full picture of the accompanying immune response has revealed a wide range of immunogenic mechanisms that include DAMP and anti-tumor mediator release, changes in local cellular immune populations, development of a systemic immune response, and therapeutic synergism with the inclusion of checkpoint inhibitor therapies. These studies also suggest that there is an immune effect from histotripsy therapies across multiple murine tumor types that may be reproducible. Overall, the effects of histotripsy on tumors show a positive effect on immunomodulation.

Wnt/β-catenin signaling pathway in uterine leiomyoma: role in tumor biology and targeting opportunities

Uterine leiomyoma is the most common tumor of the female reproductive system and originates from a single transformed myometrial smooth muscle cell. Despite the immense medical, psychosocial, and financial impact, the exact underlying mechanisms of leiomyoma pathobiology are poorly understood. Alterations of signaling pathways are thought to be instrumental in leiomyoma biology. Wnt/β-catenin pathway appears to be involved in several aspects of the genesis of leiomyomas. For example, Wnt5b is overexpressed in leiomyoma, and the Wnt/β-catenin pathway appears to mediate the role of MED12 mutations, the most common mutations in leiomyoma, in tumorigenesis. Moreover, Wnt/β-catenin pathway plays a paracrine role where estrogen/progesterone treatment of mature myometrial or leiomyoma cells leads to increased expression of Wnt11 and Wnt16, which induces proliferation of leiomyoma stem cells and tumor growth. Constitutive activation of β-catenin leads to myometrial hyperplasia and leiomyoma-like lesions in animal models. Wnt/β-catenin signaling is also closely involved in mechanotransduction and extracellular matrix regulation and relevant alterations in leiomyoma, and crosstalk is noted between Wnt/β-catenin signaling and other pathways known to regulate leiomyoma development and growth such as estrogen, progesterone, TGFβ, PI3K/Akt/mTOR, Ras/Raf/MEK/ERK, IGF, Hippo, and Notch signaling. Finally, evidence suggests that inhibition of the canonical Wnt pathway using β-catenin inhibitors inhibits leiomyoma cell proliferation. Understanding the molecular mechanisms of leiomyoma development is essential for effective treatment. The specific Wnt/β-catenin pathway molecules discussed in this review constitute compelling candidates for therapeutic targeting.

Macrophages and Immune Responses in Uterine Fibroids

Uterine fibroids represent the most common benign tumors of the uterus. They are considered a typical fibrotic disorder. In fact, the extracellular matrix (ECM) proteins—above all, collagen 1A1, fibronectin and versican—are upregulated in this pathology. The uterine fibroids etiology has not yet been clarified, and this represents an important matter about their resolution. A model has been proposed according to which the formation of an altered ECM could be the result of an excessive wound healing, in turn driven by a dysregulated inflammation process. A lot of molecules act in the complex inflammatory response. Macrophages have a great flexibility since they can assume different phenotypes leading to the tissue repair process. The dysregulation of macrophage proliferation, accumulation and infiltration could lead to an uncontrolled tissue repair and to the consequent pathological fibrosis. In addition, molecules such as monocyte chemoattractant protein-1 (MCP-1), granulocyte macrophage-colony-stimulating factor (GM-CSF), transforming growth factor-beta (TGF-β), activin A and tumor necrosis factor-alfa (TNF-α) were demonstrated to play an important role in the macrophage action within the uncontrolled tissue repair that contributes to the pathological fibrosis that represents a typical feature of the uterine fibroids.

Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome in Spain: Clinical and Genetic Characterization

Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) is a very rare hereditary disorder characterized by cutaneous leiomyomas (CLMs), uterine leiomyomas (ULMs), renal cysts (RCys) and renal cell cancers (RCCs). We aimed to describe the genetics, clinical features and potential genotype-phenotype associations in the largest cohort of fumarate hydratase enzyme mutation carriers known from Spain using a multicentre, retrospective study of individuals with a genetic or clinical diagnosis of HLRCC. We collected clinical information from medical records, analysed genetic variants and looked for genotype-phenotype associations. Analyses were performed using R 3.6.0. software. We included 197 individuals: 74 index cases and 123 relatives. CLMs were diagnosed in 65% of patients, ULMs in 90% of women, RCys in 37% and RCC in 10.9%. Twenty-seven different pathogenic variants were detected, 12 (44%) of them not reported previously. Patients with missense pathogenic variants showed higher frequencies of CLMs, ULMs and RCys, than those with loss-of-function variants (p = 0.0380, p = 0.0015 and p = 0.024, respectively). This is the first report of patients with HLRCC from Spain. The frequency of RCCs was lower than those reported in the previously published series. Individuals with missense pathogenic variants had higher frequencies of CLMs, ULMs and RCys.

Development and Validation of Hormonal Impact of a Mouse Xenograft Model for Human Uterine Leiomyoma

Multiple in vivo animal models for uterine leiomyoma do not adequately represent human disease based on etiology, molecular phenotype, or limited fixed life span. Our objective was to develop a xenograft model with sustained growth, by transplanting a well-established actively growing three-dimensional (3D) cell culture of human leiomyoma and myometrium in NOD/SCID ovariectomized female mice. We demonstrated continued growth to at least 12 weeks and the overexpression of extracellular matrix (ECM). Further, we confirmed maintenance of hormonal response that is comparable to human disease in situ. Leiomyoma xenografts under hormonal treatment demonstrated 8 to12-fold increase of volume over the xenografts not treated with hormones. Estradiol-treated xenografts were more cellular as compared to progesterone or combination milieu, at the end of 8-week time frame. There was also a non-statistically significant 2-4 mm³ increase in volume between 8-week and 12-week xenografts with higher matrix to cell ratio in 12-week xenografts compared to the 8-week and placebo xenografts. Increased expression of ECM proteins, fibronectin, versican, and collagens, indicated an actively growing cell matrix formation in the xenografts. In conclusion, we have developed and validated a xenograft in vivo model for uterine leiomyoma that shares the genomic and proteomic characteristics with the human surgical specimens of origin and recapitulates the most important features of the human tumors, the aberrant ECM expression that defines the leiomyoma phenotype and gonadal hormone regulation. Using this model, we demonstrated that combination of estradiol and progesterone resulted in increased cellularity and ECM production leading to growth of the xenograft tumors.

Endocrine disruptor exposure during development increases incidence of uterine fibroids by altering DNA repair in myometrial stem cells

Despite the major negative impact uterine fibroids (UFs) have on female reproductive health, little is known about early events that initiate development of these tumors. Somatic fibroid-causing mutations in mediator complex subunit 12 (MED12), the most frequent genetic alterations in UFs (up to 85% of tumors), are implicated in transforming normal myometrial stem cells (MSCs) into tumor-forming cells, though the underlying mechanism(s) leading to these mutations remains unknown. It is well accepted that defective DNA repair increases the risk of acquiring tumor-driving mutations, though defects in DNA repair have not been explored in UF tumorigenesis. In the Eker rat UF model, a germline mutation in the Tsc2 tumor suppressor gene predisposes to UFs, which arise due to "second hits" in the normal allele of this gene. Risk for developing these tumors is significantly increased by early-life exposure to endocrine-disrupting chemicals (EDCs), suggesting increased UF penetrance is modulated by early drivers for these tumors. We analyzed DNA repair capacity using analyses of related gene and protein expression and DNA repair function in MSCs from adult rats exposed during uterine development to the model EDC diethylstilbestrol. Adult MSCs isolated from developmentally exposed rats demonstrated decreased DNA end-joining ability, higher levels of DNA damage, and impaired ability to repair DNA double-strand breaks relative to MSCs from age-matched, vehicle-exposed rats. These data suggest that early-life developmental EDC exposure alters these MSCs' ability to repair and reverse DNA damage, providing a driver for acquisition of mutations that may promote the development of these tumors in adult life.

lncRNA expression character associated with ischemic reperfusion injury

Ischemic reperfusion injury (IRI) contributes to morbidity and mortality worldwide and results in a poor outcome for patients suffering from myocardial infarction. Ischemic post‑conditioning (IPostC), consisting of one or several brief periods of ischemia and reperfusion, generates powerful protection against IRI. The mechanism of IPostC initiation and development has previously been investigated, however still remains to be fully elucidated. Notably, long non‑coding (lnc) RNAs have previously been demonstrated to be important in cardiovascular diseases. However, there is little information about the systematic analysis of IRI‑associated lncRNA expression signature. The present study used microarrays to analyze the lncRNA expression characters of ischemic IPostc (corresponding to IRI), and demonstrated that 2,292 lncRNAs were observed to be upregulated and 1,848 lncRNAs downregulated. Gene ontology (GO) and Pathway analysis subsequently demonstrated that dysregulated lncRNAs participated in various biological processes, which are upregulated or downregulated in IPostC tissues. Finally, the present study verified that AK144818, ENS​MUS​T00000156637, ENS​MUS​T00000118342, ENS​MUS​T00000118149, uc008ane.1, ENS​MUS​T00000164933, ENS​MUS​T00000162347, ENS​MUS​T00000135945, and ENS​MUS​T00000176338, ENS​MUST00000120587, END​MUST00000155271, ENS​MUS​T00000125121 and Uc008thl.1 were associated with the initiation and development of IPostC. The present study may aid in the understanding of the initiation and development mechanisms of IPostC and provide novel and potential biomarkers that may be used in the diagnosis or as therapeutic targets in the treatment of IRI.

Recent Advances in Uterine Fibroid Etiology

Uterine fibroids, also known as uterine leiomyoma (UL), are monoclonal tumors of the smooth muscle tissue layer (myometrium) of the uterus. Although ULs are considered benign, uterine fibroids are the source of major quality-of-life issues for approximately 25% of all women, who suffer from clinically significant symptoms of UL. Despite the prevalence of UL, there is no treatment option for UL which is long term, cost-effective, and leaves fertility intact. The lack of understanding about the etiology of UL contributes to the scarcity of medical therapies available. Studies have identified an important role for sex steroid hormones in the pathogenesis of UL, and have driven the use of hormonal treatment for fibroids, with mixed results. Dysregulation of cell signaling pathways, miRNA expression, and cytogenetic abnormalities have also been implicated in UL etiology. Recent discoveries on the etiology of UL and the development of relevant genetically modified rodent models of UL have started to revitalize UL research. This review outlines the major characteristics of fibroids; major contributors to UL etiology, including steroid hormones; and available preclinical animal models for UL.

Vitamin D3 Inhibits Wnt/β-Catenin and mTOR Signaling Pathways in Human Uterine Fibroid Cells

CONTEXT

Somatic mutations in the Med12 gene are known to activate Wnt/β-catenin signaling in human uterine fibroids (UFs).

OBJECTIVE

The objective of the study was to examine the role of vitamin D3 in the modulation of Wnt/β-catenin and mammalian target of rapamycin (mTOR) signaling in human UF cells.

DESIGN

Immortalized human UF cells (HuLM) and human primary UF (PUF) cells were treated with increasing concentrations of vitamin D3 and thereafter analyzed using Western blots and immunocytochemistry.

MAIN OUTCOME MEASURES

Wnt/β-catenin and mTOR signaling proteins in cultured HuLM and PUF cells were measured.

RESULTS

UF tumors with Med12 somatic mutations showed an up-regulation of Wnt4 and β-catenin as compared with adjacent myometrium. Vitamin D3 administration reduced the levels of Wnt4 and β-catenin in both HuLM and PUF cells. Vitamin D3 also reduced the expression/activation of mTOR signaling in both cell types. In contrast, vitamin D3 induced the expression of DNA damaged-induced transcription 4 (an inhibitor of mTOR) and tuberous sclerosis genes (TSC1/2) in a concentration-dependent manner in HuLM cells. Furthermore, we observed a concentration-dependent reduction of Wisp1 (Wnt induced signaling protein 1) and flap endonuclease 1 proteins in HuLM cells. Additionally, abrogation of vitamin D receptor expression (by silencing) in normal myometrial cells induces Wnt4/β-catenin as well as prompts a fibrotic process including an increase in cell proliferation and increased extracellular matrix production. Together these results suggest that vitamin D3 functions as an inhibitor of Wnt4/β-catenin and mTOR signaling pathways, which may play major roles in fibroid pathogenesis.

CONCLUSIONS

Vitamin D3 may have utility as a novel long-term therapeutic and/or preventive option for uterine fibroids.

Early Life Adverse Environmental Exposures Increase the Risk of Uterine Fibroid Development: Role of Epigenetic Regulation

Uterine Fibroids [UF(s), AKA: leiomyoma] are the most important benign neoplastic threat to women's health. They are the most common cause of hysterectomy imposing untold personal consequences and 100s of billions of healthcare dollars, worldwide. Currently, there is no long term effective FDA-approved medical treatment available, and surgery is the mainstay. The etiology of UFs is not fully understood. In this regard, we and others have recently reported that somatic mutations in the gene encoding the transcriptional mediator subunit Med12 are found to occur at a high frequency (∼85%) in UFs. UFs likely originate when a Med12 mutation occurs in a myometrial stem cell converting it into a tumor-forming stem cell leading to a clonal fibroid lesion. Although the molecular attributes underlying the mechanistic formation of UFs is largely unknown, a growing body of literature implicates unfavorable early life environmental exposures as potentially important contributors. Early life exposure to EDCs during sensitive windows of development can reprogram normal physiological responses and alter disease susceptibility later in life. Neonatal exposure to the EDCs such as diethylstilbestrol (DES) and genistein during reproductive tract development has been shown to increase the incidence, multiplicity and overall size of UFs in the Eker rat model, concomitantly reprogramming estrogen-responsive gene expression. Importantly, EDC exposure represses enhancer of zeste 2 (EZH2) and reduces levels of histone 3 lysine 27 trimethylation (H3K27me3) repressive mark through Estrogen receptor/Phosphatidylinositide 3-kinases/Protein kinase B non-genomic signaling in the developing uterus. Considering the fact that distinct Mediator Complex Subunit 12 (Med12) mutations are detected in different fibroid lesions in the same uterus, the emergence of each Med12 mutation is likely an independent event in an altered myometrial stem cell. It is therefore possible that a chronic reduction in DNA repair capacity eventually causes the emergence of mutations such as Med12 in myometrial stem cells converting them into fibroid tumor-forming stem cells, and thereby leads to the development of UFs. Advancing our understanding of the mechanistic role epigenetic regulation of stem cells plays in mediating risk and tumorigenesis will help in pointing the way toward the development of novel therapeutic options.

The Mechanism and Function of Epigenetics in Uterine Leiomyoma Development

Uterine leiomyomas, also known as uterine fibroids, are the most common pelvic tumors, occurring in nearly 70% of all reproductive-aged women and are the leading indication for hysterectomy worldwide. The development of uterine leiomyomas involve a complex and heterogeneous constellation of hormones, growth factors, stem cells, genetic, and epigenetic abnormalities. An increasing body of evidence emphasizes the important contribution of epigenetics in the pathogenesis of leiomyomas. Genome-wide methylation analysis demonstrates that a subset of estrogen receptor (ER) response genes exhibit abnormal hypermethylation levels that are inversely correlated with their RNA expression. Several tumor suppressor genes, including Kruppel-like factor 11 (KLF11), deleted in lung and esophageal cancer 1 (DLEC1), keratin 19 (KRT19), and death-associated protein kinase 1 (DAPK1) also display higher hypermethylation levels in leiomyomas when compared to adjacent normal tissues. The important role of active DNA demethylation was recently identified with regard to the ten-eleven translocation protein 1 and ten-eleven translocation protein 3-mediated elevated levels of 5-hydroxymethylcytosine in leiomyoma. In addition, both histone deacetylase and histone methyltransferase are reported to be involved in the biology of leiomyomas. A number of deregulated microRNAs have been identified in leiomyomas, leading to an altered expression of their targets. More recently, the existence of side population (SP) cells with characteristics of tumor-initiating cells have been characterized in leiomyomas. These SP cells exhibit a tumorigenic capacity in immunodeficient mice when exposed to 17β-estradiol and progesterone, giving rise to fibroid-like tissue in vivo. These new findings will likely enhance our understanding of the crucial role epigenetics plays in the pathogenesis of uterine leiomyomas as well as point the way to novel therapeutic options.

Renal leiomyoma: a contemporary multi-institution study of an infrequent and frequently misclassified neoplasm

Renal leiomyoma is an exceptionally rare benign mesenchymal tumor of the kidney predominantly arising in proximity of the renal capsule or pelvis. Its rarity and nonspecific clinical and imaging features may lead to radical or partial nephrectomy on the basis of preoperative suspicion of renal cell carcinoma. The diagnosis of renal leiomyoma is challenging because of the histologic overlap with lipid-poor angiomyolipoma (AML). We conducted a multi-institution study to characterize renal leiomyoma in greater detail. We collected and reviewed 24 cases diagnosed initially as renal leiomyoma in 10 institutions from North America, Canada, and Europe. Immunohistochemical expression of desmin, HMB-45, estrogen receptor (ER), progesterone receptor (PR), and cathepsin K was evaluated. Upon central review, 9 tumors were classified as renal leiomyoma, whereas the remaining were reclassified as AML (n=13), myolipoma (n=1), and medullary fibroma (n=1). All renal leiomyomas were solitary and occurred in female patients (mean age 63 y; range, 44 to 74 y). Tumor size ranged from 0.6 to 7.0 cm (mean 2.9 cm); 7 originated from the renal capsule or the subcapsular area and 1 from a large vessel in the renal sinus. All leiomyomas were diffusely positive for desmin and negative for HMB-45 and cathepsin K; 6/9 (67%) showed diffuse ER and PR expression, and 1 case showed focal ER positivity only. Renal leiomyoma should be included in the histologic differential diagnosis of solid renal masses, particularly in perimenopausal women. The main differential diagnosis is with lipid-poor AML, and cathepsin K plays a key role in distinguishing these 2 lesions.

The role of HIF1α in renal cell carcinoma tumorigenesis

The transcription factor HIF1α is implicated in the development of clear cell renal cell carcinoma (ccRCC). Although HIF1α was initially believed to be essential for ccRCC development, recent studies hypothesize an oncogenic role for HIF2α in ccRCC, but a tumor suppressor role for HIF1α, leading to uncertainty as to the precise roles of the different HIF transcription factors in this disease. Using evidence available from studies with human ccRCC cell lines, mouse xenografts, murine models of ccRCC, and human ccRCC specimens, we evaluate the roles of HIF1α and HIF2α in the pathogenesis of ccRCC. We present a convergence of clinical and mechanistic data supporting an important role for HIF1α in promoting tumorigenesis in a clinically important and large subset of ccRCC. This indicates that current understanding of the exact roles of HIF1α and HIF2α is incomplete and that further research is required to determine the diverse roles of HIF1α and HIF2α in ccRCC.

KEY MESSAGES

The TRACK mouse ccRCC model with constitutively active HIF1α but not HIF2α expressed in proximal tubules develops RCC. HIF1α protein is expressed in the majority of human ccRCC specimens. Elevated HIF1α in ccRCC correlates with a worse prognosis. Many publications do not support a tumor suppressor role for HIF1α in ccRCC. HIF1α, but not HIF2α, is expressed in some types of cancer stem cells.

Loss of the repressor REST in uterine fibroids promotes aberrant G protein-coupled receptor 10 expression and activates mammalian target of rapamycin pathway

Uterine fibroids (leiomyomas) are the most common tumors of the female reproductive tract, occurring in up to 77% of reproductive-aged women, yet molecular pathogenesis remains poorly understood. A role for atypically activated mammalian target of rapamycin (mTOR) pathway in the pathogenesis of uterine fibroids has been suggested in several studies. We identified that G protein-coupled receptor 10 [GPR10, a putative signaling protein upstream of the phosphoinositide 3-kinase-protein kinase B/AKT-mammalian target of rapamycin (PI3K/AKT-mTOR) pathway] is aberrantly expressed in uterine fibroids. The activation of GPR10 by its cognate ligand, prolactin releasing peptide, promotes PI3K-AKT-mTOR pathways and cell proliferation specifically in cultured primary leiomyoma cells. Additionally, we report that RE1 suppressing transcription factor/neuron-restrictive silencing factor (REST/NRSF), a known tumor suppressor, transcriptionally represses GPR10 in the normal myometrium, and that the loss of REST in fibroids permits GPR10 expression. Importantly, mice overexpressing human GPR10 in the myometrium develop myometrial hyperplasia with excessive extracellular matrix deposition, a hallmark of uterine fibroids. We demonstrate previously unrecognized roles for GPR10 and its upstream regulator REST in the pathogenesis of uterine fibroids. Importantly, we report a unique genetically modified mouse model for a gene that is misexpressed in uterine fibroids.

Validation of the aging hen (Gallus gallus domesticus) as an animal model for uterine leiomyomas

Uterine leiomyomas, or fibroids, are the most frequent gynecological tumors in premenopausal women with as many as 65% of women becoming clinically symptomatic. Uterine fibroids are benign myometrial tumors that produce large quantities of extracellular matrix proteins. Despite its high morbidity, the molecular basis underlying the development of uterine leiomyomas is not well understood. Domestic hens of Gallus gallus domesticus develop oviductal leiomyomas similar to those found in humans. We investigated the natural history of chicken leiomyomas, in vivo expression of protein biomarkers, and in vitro expression of ovarian steroid receptors. Based on the analysis of 263 hens, tumor prevalence, tumor number per hen, and tumor size increased as the hens aged. Immunohistochemistry for alpha-smooth muscle actin (SMA) and desmin confirmed the smooth muscle phenotype of the chicken leiomyomas. Intense collagen expression was detected in these oviductal leiomyomas by Mason's trichrome, and the tumors also showed increased expression of TGFB3 and collagen type I mRNAs. Consistent with human leiomyomas, chicken fibroids displayed increased BCL2 and estrogen (E) and progesterone (P) receptor expression. Chicken leiomyomas were dissociated for in vitro culture. Cells from explants were positive for SMA, desmin, and E and P receptors until the fourth passage. These cells also displayed a response similar to human cells when challenged with halofuginone, an antifibrotic agent. Our findings indicate that the chicken is an excellent complementary model for studies involving the pathophysiology of human uterine leiomyomas.

Biology of metastatic renal cell carcinoma

In the past ten years we have made exceptional progresses in the understanding of RCC biology, particularly by recognizing the crucial pathogenetic role of activation of the HIF/VEGF and mTOR pathways. This has resulted in the successful clinical development of anti-angiogenic and mTOR-targeted drugs, which have profoundly impacted on the natural history of the disease and have improved the duration and quality of RCC patient lives. However, further improvements are still greatly needed: 1) even in patients who obtain striking clinical responses early in the course of treatment, disease will ultimately escape control and progress to a treatment-resistant state, leading to therapeutic failure; 2) prolonged disease control usually requires 'continuous' treatment, even across different treatment lines, making the impact of chronic, low-grade, toxicities on quality of life greater and precluding, for most patients, the possibility of experiencing 'drug-free holidays'; 3) although we have successfully identified classes of drugs (or molecular mechanisms of action) that are effective in a substantial proportion of patients, we still fall short of molecular predictive factors that identify individual patients who will (or will not) benefit from a specific intervention and still proceed on a trial-and-error basis, far from a truly 'personalized' therapeutic approach; 4) finally (and perhaps most importantly), even in the best case scenario, currently available treatments inevitably fail to definitively 'cure' metastatic RCC patients. In this review we briefly summarize recent developments in the understanding of the molecular pathogenesis of RCC, the development of resistance/escape mechanisms, the rationale for sequencing agents with different mechanisms of action, and the importance of host-related factors. Unraveling the complex mechanisms by which RCC shapes host microenvironment and immune response and therapeutic treatments, in turn, shape both cancer cell biology and tumor-host interactions may hold the key to future advances in such a complex and challenging disease.

The long and winding road to rational treatment of cancer associated with LKB1/AMPK/TSC/mTORC1 signaling

The liver kinase B1 (LKB1)/adenosine mono-phosphate-activated protein kinase (AMPK)/tuberous sclerosis complex (TSC)/mammalian target of rapamycin (mTOR) complex (mTORC1) cassette constitutes a canonical signaling pathway that integrates information on the metabolic and nutrient status and translates this into regulation of cell growth. Alterations in this pathway are associated with a wide variety of cancers and hereditary hamartoma syndromes, diseases in which hyperactivation of mTORC1 has been described. Specific mTORC1 inhibitors have been developed for clinical use, and these drugs have been anticipated to provide efficient treatment for these diseases. In the present review, we provide an overview of the metabolic LKB1/AMPK/TSC/mTORC1 pathway, describe how its aberrant signaling associates with cancer development, and indicate the difficulties encountered when biochemical data are extrapolated to provide avenues for rational treatment of disease when targeting this signaling pathway. A careful examination of preclinical and clinical studies performed with rapamycin or derivatives thereof shows that although results are encouraging, we are only half way in the long and winding road to design rationale treatment targeted at the LKB1/AMPK/TSC/mTORC1 pathway. Inherited cancer syndromes associated with this pathway such as the Peutz-Jeghers syndrome and TSC, provide perfect models to study the relationship between genetics and disease phenotype, and to delineate the complexities that underlie translation of biochemical and genetical information to clinical management, and thus provide important clues for devising novel rational medicine for cancerous diseases in general.

Comparison of human and rat uterine leiomyomata: identification of a dysregulated mammalian target of rapamycin pathway

Uterine leiomyomata, or fibroids, are benign tumors of the uterine myometrium that significantly affect up to 30% of reproductive-age women. Despite being the primary cause of hysterectomy in the United States, accounting for up to 200,000 procedures annually, the etiology of leiomyoma remains largely unknown. As a basis for understanding leiomyoma pathogenesis and identifying targets for pharmacotherapy, we conducted transcriptional profiling of leiomyoma and unaffected myometrium from humans and Eker rats, the best characterized preclinical model of leiomyomata. A global comparison of mRNA from leiomyoma versus myometrium in human and rat identified a highly significant overlap of dysregulated gene expression in leiomyomata. An unbiased pathway analysis using a method of gene-set enrichment based on the sigPathway algorithm detected the mammalian target of rapamycin (mTOR) pathway as one of the most highly up-regulated pathways in both human and rat tumors. To validate this pathway as a therapeutic target for uterine leiomyomata, preclinical studies were conducted in Eker rats. These rats develop uterine leiomyomata as a consequence of loss of Tsc2 function and up-regulation of mTOR signaling. Inhibition of mTOR in female Eker rats with the rapamycin analogue WAY-129327 for 2 weeks decreased mTOR signaling and cell proliferation in tumors, and treatment for 4 months significantly decreased tumor incidence, multiplicity, and size. These results identify dysregulated mTOR signaling as a component of leiomyoma etiology across species and directly show the dependence of uterine leiomyomata with activated mTOR on this signaling pathway for growth.

Distinctive morphology of renal cell carcinomas in tuberous sclerosis

Tuberous sclerosis complex results from mutations in 1 of 2 interacting gene products, hamartin or tuberin. The syndrome is characterized by hamartomas and neoplastic lesions, including angiomyolipomas of the kidney and other organs. Renal cell carcinoma (RCC) in tuberous sclerosis remains relatively poorly characterized because historical studies were confounded by the inclusion of epithelioid angiomyolipomas. The authors present a patient with tuberous sclerosis and bilateral renal lesions, including multiple minute angiomyolipomas, cortical cysts, and 4 separate RCCs of unclassified type. The carcinomas shared distinctive morphological features, including sheet-like, glandular, trabecular, or cystic architecture and abundant granular eosinophilic cytoplasm. By definition, the carcinomas were keratin positive and negative for HMB-45 and Melan-A. Detailed immunohistochemical analysis revealed heterogeneity among the cortical cysts and carcinomas. The histopathological features of these carcinomas illustrate characteristics of renal carcinoma that are probably related to genetic alterations of tuberous sclerosis.

Towards fibroid gene therapy: adenovirus-mediated delivery of herpes simplex virus 1 thymidine kinase gene/ganciclovir shrinks uterine leiomyoma in the Eker rat model

BACKGROUND/AIMS

The objective of this study was to assess in vivo gene therapy of uterine leiomyomas in the Eker rat model using adenovirus (Ad)-mediated delivery of herpes simplex virus 1 thymidine kinase gene (HSV1TK) followed by ganciclovir (GCV) treatment.

METHODS

We randomized 27 female Eker rats with MRI-confirmed uterine leiomyomas to a single treatment with direct intra-tumor injection of Ad-HSV1TK/GCV, Ad-LacZ/GCV, or medium alone. Samples were collected from tumors, other body organs, and blood at 10, 20, and 30 days after treatment to assess the safety and efficacy of the treatment.

RESULTS

Ad-HSV1TK/GCV treatment significantly decreased uterine fibroid volume by 75 +/- 16, 58.7 +/- 6.3, and 67.5 +/- 27.5%, of the pretreatment volume at days 10, 20, and 30, respectively. Ad-HSV1TK/GCV increased caspase-3 activity, Bax expression, and TUNEL apoptosis marker, and it decreased cyclin D1, PCNA, Bcl2, and PARP protein expressions. Ad transfection induced local CD4+ and CD8+ infiltration and serum anti-Ad antibodies. Additionally, Ad transfection was tumor-localized and safe to non-target tissues.

CONCLUSION

These studies demonstrate a marked efficiency and high safety for the Ad-HSV1TK/GCV therapeutic approach in the context of Eker rat uterine leiomyomas and provide essential preclinical data for the development of Ad-HSV1TK/GCV gene therapy for uterine fibroids.

Gene therapy targeting leiomyoma: adenovirus-mediated delivery of dominant-negative estrogen receptor gene shrinks uterine tumors in Eker rat model

OBJECTIVE

To evaluate the utility of gene therapy for uterine fibroids in the Eker rat model using an adenovirus-mediated delivery of a dominant-negative estrogen receptor gene (Ad-DNER).

DESIGN

Animal study.

SETTING

University animal laboratory.

ANIMAL(S)

Twenty-seven female Eker rats.

INTERVENTION(S)

We randomized Eker rats with magnetic resonance imaging (MRI)-confirmed uterine leiomyomas to a single treatment of direct intrafibroid injection with Ad-DNER, Ad-bacterial ss-galactosidase, or vehicle.

MAIN OUTCOME MEASURE(S)

Tumor volumes were determined by MRI scanning and caliper measurement. Samples of serum, fibroid tumors, and various organs were collected at 8, 15, and 30 days after treatment to assess treatment safety and efficacy.

RESULT(S)

The Ad-DNER treatment significantly decreased uterine fibroid volume by 45%, 80%, and 77.4% of pretreatment volume at days 8, 15, and 30, respectively, and modulated the expression of apoptosis-, proliferation-, and extracellular matrix-related genes' compared with control animals. The Ad-DNER did not produce any toxic effects in nontarget tissues.

CONCLUSION(S)

The Ad-DNER treatment shrinks Eker rats' fibroids, in part, via modulation of several estrogen-regulated genes. This safe gene therapy approach presents a promising conservative treatment option for women with symptomatic uterine fibroids.

Developmental reprogramming of IGF signaling and susceptibility to endometrial hyperplasia in the rat

In rodents, a brief neonatal exposure of the developing reproductive tract to the xenoestrogen, diethylstilbestrol (DES) reprograms developing tissues to increase susceptibility to tumorigenesis in adult animals, including uterine adenocarcinoma. Progression from a normal endometrium to carcinoma occurs via the intermediate stage of endometrial hyperplasia. We previously reported that endometrial hyperplasia in postmenopausal women is linked to abnormal insulin-like growth factor-I (IGF-I) signaling. To identify early events involved in the development of hyperplasia in the endometrium, we examined expression and activation of IGF-I pathway components in endometrium of rats exposed to DES. By 5 months of age, 36/60 (60%) of rats exposed to DES on days 3-5 after birth developed endometrial hyperplasia compared to 0% of vehicle-treated controls. Consistent with activation of a mitogenic signaling pathway, Ki67-positive cells increased in DES-exposed endometrium despite compromised ovarian function and hypoestrogenic milieu characteristic of DES-exposed animals. The endometrium of DES-exposed rats overexpressed IGF-II and insulin receptor substrate-1 (IRS-1) and exhibited elevated Akt expression and activation (as judged by phosphorylation) and mTOR signaling (phosphorylation of S6) compared to vehicle-treated endometrium. In contrast to vehicle-treated endometrium, in which negative feedback to IRS-1 was observed (phosphorylation of S636/639), negative feedback to IRS-1 was absent in DES-exposed endometrium. These data support a central role for IGF-I signaling in the development of both human and rodent endometrial hyperplasia. Furthermore, both global activation of IGF-IR signaling and abrogation of negative feedback to IRS-1 appear to be reprogrammed by DES in endometrial hyperplasia, implicating for the first time loss of negative feedback to IRS-1 in development of a preneoplastic lesion.

Tumor-specific efficacy of transforming growth factor-beta RI inhibition in Eker rats

PURPOSE

Transforming growth factor beta (TGF-beta), which generally stimulates the growth of mesenchymally derived cells but inhibits the growth of epithelial cells, has been proposed as a possible target for cancer therapy. However, concerns have been raised that whereas inhibition of TGF-beta signaling could be efficacious for lesions in which TGF-beta promotes tumor development and/or progression, systemic pharmacologic blockade of this signaling pathway could also promote the growth of epithelial lesions.

EXPERIMENTAL DESIGN

We examined the effect of a TGF-beta inhibitor on mesenchymal (leiomyoma) and epithelial (renal cell carcinoma) tumors in Eker rats, which are genetically predisposed to develop these tumors with a high frequency.

RESULTS

Blockade of TGF-beta signaling with the ALK5/type I TGF-beta R kinase inhibitor, SB-525334, was efficacious for uterine leiomyoma; significantly decreasing tumor incidence and multiplicity, and reducing the size of these mesenchymal tumors. However, SB-525334 was also mitogenic and antiapoptotic for epithelial cells in the kidney and exacerbated the growth of epithelial lesions present in the kidneys of these animals.

CONCLUSION

Although pharmacologic inhibition of TGF-beta signaling with SB-525334 may be efficacious for mesenchymal tumors, inhibition of this signaling pathway seems to promote the development of epithelial tumors.

Role of carbonic anhydrases in the progression of renal cell carcinoma subtypes: proposal of a unified hypothesis

Renal cell carcinoma (RCC) has the highest rate of occurrence within the US when compared with other countries. Recent advances in the basic research and molecular diagnostics of this malignancy have revealed that RCC is not a single disease, but it is a mixture of several types of malignancies with unique molecular mechanisms and pathological attributes. RCC is now divided into clear cell carcinoma (80% of all kidney cancers), papillary type 1 and papillary type 2 neoplasms (10-15% of all RCC patients) and RCC with chromophobic and oncocytic features, called the Birt-Hogg-Dube (BHD) subtype, in roughly 5% of all patients. Apart from these, neoplasms such as the tuberous sclerosis (TSC) syndrome may occur with a mixed pathological features with a renal presentation. In this review, molecular evidence, both direct and indirect, published so far on all these RCC subtypes have been analyzed to find out whether there is any common thread that could run through these disparate malignancies that happen to occur in a single organ, i.e., the kidney. We believe that the role played by the expression and certain non-traditional activities of the cabonic anhydrase (CA) family members, along with the differing levels of hypoxia induced within these tumors may be the most common denominators. Evidence is presented focusing on how the CA family members could participate in the genesis and progression of each and every one of these RCC subtypes and how their function could be influenced by hypoxia, activities of receptor type protein tyrosine kinases and certain other pre-disposing factors. These rationalizations point towards a unified hypothesis that may help explain the occurrence of all these RCC subtypes in a molecular manner. We hope that these analyses would a) stimulate further studies aimed toward a better understanding of the role played by carbonic anhydrases in RCC subtypes and b) would pave way to a better and rationally designed therapies to interfere with their function to benefit patients with RCC and possibly other cancers.

Spontaneous Uterine Leiomyosarcoma in a Golden Hamster (Mesocrietus auratus)

Uterine leiomyosarcoma occurring spontaneously in a domestic golden hamster was examined histologically and immunohistochemically. The histological findings for this tumour were similar to those for leiomyosarcomas described in other species. Immunohistochemical examination demonstrated the positivity of neoplastic cells with alpha-smooth muscle actin and desmin. From the results mentioned above, the tumour of this case was revealed to be of smooth muscle origin. To our knowledge, this is the first report of a uterine leiomyosarcoma in domestic golden hamsters.

Folliculin encoded by the BHD gene interacts with a binding protein, FNIP1, and AMPK, and is involved in AMPK and mTOR signaling

Birt-Hogg-Dubé syndrome, a hamartoma disorder characterized by benign tumors of the hair follicle, lung cysts, and renal neoplasia, is caused by germ-line mutations in the BHD(FLCN) gene, which encodes a tumor-suppressor protein, folliculin (FLCN), with unknown function. The tumor-suppressor proteins encoded by genes responsible for several other hamartoma syndromes, LKB1, TSC1/2, and PTEN, have been shown to be involved in the mammalian target of rapamycin (mTOR) signaling pathway. Here, we report the identification of the FLCN-interacting protein, FNIP1, and demonstrate its interaction with 5' AMP-activated protein kinase (AMPK), a key molecule for energy sensing that negatively regulates mTOR activity. FNIP1 was phosphorylated by AMPK, and its phosphorylation was reduced by AMPK inhibitors, which resulted in reduced FNIP1 expression. AMPK inhibitors also reduced FLCN phosphorylation. Moreover, FLCN phosphorylation was diminished by rapamycin and amino acid starvation and facilitated by FNIP1 overexpression, suggesting that FLCN may be regulated by mTOR and AMPK signaling. Our data suggest that FLCN, mutated in Birt-Hogg-Dubé syndrome, and its interacting partner FNIP1 may be involved in energy and/or nutrient sensing through the AMPK and mTOR signaling pathways.

Gene therapy of uterine leiomyoma: adenovirus-mediated herpes simplex virus thymidine kinase/ganciclovir treatment inhibits growth of human and rat leiomyoma cells in vitro and in a nude mouse model

Uterine leiomyomas (LM) affect a high percentage of reproductive-age women. They develop as discrete, well-defined tumors that are easily accessible with imaging techniques--making this disease ideal for localized gene therapy approaches. In this study, we determined the efficacy of adenovirus-mediated herpes simplex virus thymidine kinase gene transfer in combination with ganciclovir (Ad-TK/GCV) as a potential therapy for LM. Rat ELT-3 LM cells and human LM cells were transfected with different multiplicity of infections (10-100 plaque forming units [PFU]/cell) of Ad-TK and treated with GCV (5, 10, or 20 microg/ml) for 5 days. To test the bystander effect, Ad-TK-transfected ELT-3 cells (100 PFU/cell) or LM cells (10 PFU/cell) were cocultured with corresponding nontransfected cells at increasing percentages and treated with GCV followed by cell counting. In ELT-3 cells transfected with Ad-TK/GCV (10, 20, 50, or 100 PFU/cell), the cell count was reduced by 24, 42, 77, and 87%, respectively, compared with the control cells (transfected with Ad-Lac Z/GCV). Similarly, in LM cells transfected with Ad-TK/GCV (10, 50, or 100 PFU/cell), the cell count was reduced by 31, 62, and 82%, respectively, compared with the control. A strong bystander effect was noted in both ELT-3 and LM cells with significant killing (p = 0.001) at a ratio of infected:uninfected cells of only 1:99 and maximal killing at 1:4. This study demonstrates the potential efficacy of the Ad-TK/GCV gene therapy approach as a viable nonsurgical alternative treatment for uterine LM.

Gene therapy and uterine leiomyoma: a review

Leiomyomas (fibroids) are common estrogen-dependent uterine tumours that cause significant morbidity for women and a substantial economic impact on health delivery systems. Currently, there is no effective medical treatment option for this condition-hysterectomy is the mainstay of management. This is not an attractive choice for many women, especially patients desiring to preserve their fertility potential. Gene therapy is becoming a clinical reality, with more than 600 clinical trials worldwide. Researchers have recently attempted to develop a gene-therapy-based approach for the ablation of uterine fibroids. The localized nature of this condition and its accessibility using different imaging or endoscopic techniques make it an attractive target for direct delivery of gene-based vectors. Recent work from our laboratory suggests the potential use of a dominant-negative form of estrogen receptor (ER) to inactivate estrogen signalling in leiomyoma cells and induce apoptosis. Our in vivo data in a mouse model demonstrate the ability of an adenovirus-expressing dominant-negative ER to arrest leiomyoma growth. We and others also have described the utility of the herpes simplex virus-thymidine kinase (HSV-TK) plus ganciclovir (GCV) suicide gene-therapy system to effectively eradicate leiomyoma cells by utilizing the bystandard effect phenomena and the high expression of gap-junction protein in these tumours. Further work on rat models will pave the way for future leiomyoma gene-therapy clinical trials and allow the realization of gene therapy as a viable non-surgical option for this common problem in women's health.

Uterine fibroids: the elephant in the room

Uterine fibroids (leiomyomas) have historically been viewed as important chiefly as the major indication for hysterectomy. As new therapies are developed, the heterogeneity of this disease becomes therapeutically relevant. An awareness of the role of genetics, the extracellular matrix, and hormones in tumor etiology is key to understanding this disease.