Synthetically Lethal Interactions of Heme Oxygenase-1 and Fumarate Hydratase Genes

Elevated expression of heme oxygenase-1 (HO-1, encoded by HMOX1) is observed in various types of tumors. Hence, it is suggested that HO-1 may serve as a potential target in anticancer therapies. A novel approach to inhibit HO-1 is related to the synthetic lethality of this enzyme and fumarate hydratase (FH). In the current study, we aimed to validate the effect of genetic and pharmacological inhibition of HO-1 in cells isolated from patients suffering from hereditary leiomyomatosis and renal cell carcinoma (HLRCC)-an inherited cancer syndrome, caused by FH deficiency. Initially, we confirmed that UOK 262, UOK 268, and NCCFH1 cell lines are characterized by non-active FH enzyme, high expression of Nrf2 transcription factor-regulated genes, including HMOX1 and attenuated oxidative phosphorylation. Later, we demonstrated that shRNA-mediated genetic inhibition of HMOX1 resulted in diminished viability and proliferation of cancer cells. Chemical inhibition of HO activity using commercially available inhibitors, zinc and tin metalloporphyrins as well as recently described new imidazole-based compounds, especially SLV-11199, led to decreased cancer cell viability and clonogenic potential. In conclusion, the current study points out the possible relevance of HO-1 inhibition as a potential anti-cancer treatment in HLRCC. However, further studies revealing the molecular mechanisms are still needed.

Fumarate Metabolic Signature for the Detection of Reed Syndrome in Humans

PURPOSE

Inherited pathogenic variants in genes encoding the metabolic enzymes succinate dehydrogenase (SDH) and fumarate hydratase predispose to tumor development through accumulation of oncometabolites (succinate and fumarate, respectively; ref. 1). Noninvasive in vivo detection of tumor succinate by proton magnetic resonance spectroscopy (1H-MRS) has been reported in SDH-deficient tumors, but the potential utility of this approach in the management of patients with hereditary leiomyomatosis and renal cell cancer syndrome or Reed syndrome is unknown.

EXPERIMENTAL DESIGN

Magnetic resonance spectroscopy (1H-MRS) was performed on three cases and correlated with germline genetic results and tumor IHC when available.

RESULTS

Here, we have demonstrated a proof of principle that 1H-MRS can provide a noninvasive diagnosis of hereditary leiomyomatosis and renal cell cancer syndrome or Reed syndrome through detection of fumarate accumulation in vivo.

CONCLUSIONS

This study demonstrates that in vivo detection of fumarate could be employed as a functional biomarker.

Review: Warburg effect and renal cancer caused by errs in fumarate hydratase encoding gene

The several types of heterogeneous kidney cancers are interrelated by their primary sites of pathology. Despite its origin in the kidney, renal cell carcinoma (RCC) is associated with its varying genetic basis. Von Hippel-Lindau (VHL) syndrome is the earliest and, thus the most highly, characterized of genetic forms of kidney cancer, which is associated with alterations in the Von Hippel-Lindau (VHL) gene. As a result of his studies and investigations, Otto Warburg reached the conclusion that cancer's fundamental cause is altered mechanism. But this theory was disdained because of the discovery of tumor suppressor genes and oncogenes. Lately, the breakthrough finding about the tumor suppressing role of gene coding for enzymes involved in Krebs cycle has revived the interest in Warburg's hypothesis. This effect has led to the uncovering of the links between metabolic alterations, mitochondrial dysfunction and cancer. One such metastatic cancer characterized by the germ-line inactivating mutation of the gene coding for fumarate hydratase (FH), a Krebs cycle's enzyme, is hereditary leiomyomatosis and renal cell carcinoma (HLRCC). In this review paper, we have discussed the background of this carcinoma, the metabolic dysfunction causing it and its therapeutic solutions.

Piloleiomyomas in multiple cutaneous and uterine leiomyoma syndrome (hereditary leiomyomatosis and renal cell cancer or Reed syndrome)

Multiple cutaneous and uterine leiomyoma (MCL), or Reed syndrome is an uncommon condition that includes cutaneous piloleiomyomas and internal neoplasms of the uterus and kidney. Clinical findings include clusters of variably-painful, skin-colored-to-red-brown papules. Genetic testing shows germline mutations in the gene encoding fumarate hydratase. We describe a patient with MCL who presented with subtle cutaneous findings. We believe it is important that dermatologists consider a diagnosis of MCL when presented with patients with small painful dermal papules.

The opioid neuropeptides in uterine fibroid pseudocapsules: a putative association with cervical integrity in human reproduction

The myoma pseudocapsule (MP) is a fibro-vascular network rich of neurotransmitters, as a neurovascular bundle, surrounding fibroid and separating myoma from myometrium. We investigated the distribution of the opioid neuropeptides, as enkephalin (ENK) and oxytocin (OXT), in the nerve fibers within MP and their possible influence in human reproduction in 57 women. An histological and immunofluorescent staining of OXT and ENK was performed on nerve fibers of MP samples from the fundus, corpus and isthmian-cervical regions, with a successive morphometric quantification of OXT and ENK. None of the nerve fibers in the uterine fundus and corpus MPs contained ENK and the nerve fibers in the isthmian-cervical region demonstrated an ENK value of up to 94 ± 0.7 CU. A comparatively lower number of OXT-positive nerve fibers were found in the fundal MP (6.3 ± 0.8 CU). OXT-positive nerve fibers with OXT were marginally increased in corporal MP (15.0 ± 1.4 CU) and were substantially higher in the isthmian-cervical region MP (72.1 ± 5.1 CU) (p < 0.01). The distribution of OXY neurofibers showed a slight into the uterine corpus, while are highly present into the cervico-isthmic area, with influence on reproductive system and sexual disorders manifesting after surgical procedures on the cervix.

Metabolic reprogramming for producing energy and reducing power in fumarate hydratase null cells from hereditary leiomyomatosis renal cell carcinoma

Fumarate hydratase (FH)-deficient kidney cancer undergoes metabolic remodeling, with changes in mitochondrial respiration, glucose, and glutamine metabolism. These changes represent multiple biochemical adaptations in glucose and fatty acid metabolism that supports malignant proliferation. However, the metabolic linkages between altered mitochondrial function, nucleotide biosynthesis and NADPH production required for proliferation and survival have not been elucidated. To characterize the alterations in glycolysis, the Krebs cycle and the pentose phosphate pathways (PPP) that either generate NADPH (oxidative) or do not (non-oxidative), we utilized [U-¹³C]-glucose, [U-¹³C,¹⁵N]-glutamine, and [1,2- ¹³C₂]-glucose tracers with mass spectrometry and NMR detection to track these pathways, and measured the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) of growing cell lines. This metabolic reprogramming in the FH null cells was compared to cells in which FH has been restored. The FH null cells showed a substantial metabolic reorganization of their intracellular metabolic fluxes to fulfill their high ATP demand, as observed by a high rate of glucose uptake, increased glucose turnover via glycolysis, high production of glucose-derived lactate, and low entry of glucose carbon into the Krebs cycle. Despite the truncation of the Krebs cycle associated with inactivation of fumarate hydratase, there was a small but persistent level of mitochondrial respiration, which was coupled to ATP production from oxidation of glutamine-derived α–ketoglutarate through to fumarate. [1,2- ¹³C₂]-glucose tracer experiments demonstrated that the oxidative branch of PPP initiated by glucose-6-phosphate dehydrogenase activity is preferentially utilized for ribose production (56-66%) that produces increased amounts of ribose necessary for growth and NADPH. Increased NADPH is required to drive reductive carboxylation of α-ketoglutarate and fatty acid synthesis for rapid proliferation and is essential for defense against increased oxidative stress. This increased NADPH producing PPP activity was shown to be a strong consistent feature in both fumarate hydratase deficient tumors and cell line models.

Inhibition of mitochondrial aconitase by succination in fumarate hydratase deficiency

The gene encoding the Krebs cycle enzyme fumarate hydratase (FH) is mutated in hereditary leiomyomatosis and renal cell cancer (HLRCC). Loss of FH activity causes accumulation of intracellular fumarate, which can directly modify cysteine residues to form 2-succinocysteine through succination. We undertook a proteomic-based screen in cells and renal cysts from Fh1 (murine FH)-deficient mice and identified 94 protein succination targets. Notably, we identified the succination of three cysteine residues in mitochondrial Aconitase2 (ACO2) crucial for iron-sulfur cluster binding. We show that fumarate exerts a dose-dependent inhibition of ACO2 activity, which correlates with increased succination as determined by mass spectrometry, possibly by interfering with iron chelation. Importantly, we show that aconitase activity is impaired in FH-deficient cells. Our data provide evidence that succination, resulting from FH deficiency, targets and potentially alters the function of multiple proteins and may contribute to the dysregulated metabolism observed in HLRCC.

NT, NPY and PGP 9.5 presence in myomeytrium and in fibroid pseudocapsule and their possible impact on muscular physiology

The uterine myoma pseudocapsule is a neurovascular bundle surrounding fibroid, containing neuropeptides, probably involved in uterine scar healing. We studied neurotensin (NT), neuropeptide tyrosine (NPY), and protein gene product 9.5 (PGP 9.5) nerve fibres in the pseudocapsule neurovascular bundle of intramural uterine fibroids on 67 no pregnant women by intracapsular myomectomy sparing the neurovascular bundle, sampling full thickness specimens of the pseudocapsule of uterine fibroids (PUF) and normal myometrium (NM) obtained from the fundus uteri (FU) and the uterine body (UB). The samples were sent for histological and immunofluorescent analyses and compared by morphometrical quantification. The Conventional Unit (C.U.) difference of NT, NPY, and PGP 9.5 nerve fibres was statistically analyzed. Our results showed that NT, NPY, and PGP 9.5 neurofibers are almost equally present in PUF as in NM of a no pregnant uterus. As all of these neuropeptides are present in the uterine muscle and can affect muscle contractility, uterine peristalsis and muscular healing. A myomectomy respecting the pseudocapsule neurofibers should facilitate smooth muscle scarring and promote restoration of normal uterine peristalsis with a possible positive influence on fertility.

Protein profiling of blood samples from patients with hereditary leiomyomatosis and renal cell cancer by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an extremely rare syndrome with autosomal dominant inheritance. HLRCC is characterized by a predisposition to leiomyomas of the skin and the uterus as well as renal cell carcinoma. The disease-related gene has been identified as fumarate hydratase (fumarase, FH), which encodes an enzyme involved in the mitochondrial tricarboxylic acid cycle. Protein profiling may give some insight into the molecular pathways of HLRCC. Therefore, we performed protein profiling of blood samples from HLRCC patients, their family members, and healthy volunteers, using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) coupled with IMAC-Cu chips. For hierarchical clustering analysis, we used the 45 peaks that revealed significant differences in single-marker analysis over the range from 1500 to 15,000 m/z. Heat map analysis based on the results of clustering distinguished the HLRCC kindred from non-HLRCC subjects with a sensitivity of 94% and a specificity of 90%. SELDI-TOF MS profiling of blood samples can be applied to identify patients with HLRCC and to assess specific molecular mechanisms involved in this condition.

The glycolytic shift in fumarate-hydratase-deficient kidney cancer lowers AMPK levels, increases anabolic propensities and lowers cellular iron levels

Inactivation of the TCA cycle enzyme, fumarate hydratase (FH), drives a metabolic shift to aerobic glycolysis in FH-deficient kidney tumors and cell lines from patients with hereditary leiomyomatosis renal cell cancer (HLRCC), resulting in decreased levels of AMP-activated kinase (AMPK) and p53 tumor suppressor, and activation of the anabolic factors, acetyl-CoA carboxylase and ribosomal protein S6. Reduced AMPK levels lead to diminished expression of the DMT1 iron transporter, and the resulting cytosolic iron deficiency activates the iron regulatory proteins, IRP1 and IRP2, and increases expression of the hypoxia inducible factor HIF-1α, but not HIF-2α. Silencing of HIF-1α or activation of AMPK diminishes invasive activities, indicating that alterations of HIF-1α and AMPK contribute to the oncogenic growth of FH-deficient cells.

Expression profiling in progressive stages of fumarate-hydratase deficiency: the contribution of metabolic changes to tumorigenesis

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is caused by mutations in the Krebs cycle enzyme fumarate hydratase (FH). It has been proposed that "pseudohypoxic" stabilization of hypoxia-inducible factor-α (HIF-α) by fumarate accumulation contributes to tumorigenesis in HLRCC. We hypothesized that an additional direct consequence of FH deficiency is the establishment of a biosynthetic milieu. To investigate this hypothesis, we isolated primary mouse embryonic fibroblast (MEF) lines from Fh1-deficient mice. As predicted, these MEFs upregulated Hif-1α and HIF target genes directly as a result of FH deficiency. In addition, detailed metabolic assessment of these MEFs confirmed their dependence on glycolysis, and an elevated rate of lactate efflux, associated with the upregulation of glycolytic enzymes known to be associated with tumorigenesis. Correspondingly, Fh1-deficient benign murine renal cysts and an advanced human HLRCC-related renal cell carcinoma manifested a prominent and progressive increase in the expression of HIF-α target genes and in genes known to be relevant to tumorigenesis and metastasis. In accord with our hypothesis, in a variety of different FH-deficient tissues, including a novel murine model of Fh1-deficient smooth muscle, we show a striking and progressive upregulation of a tumorigenic metabolic profile, as manifested by increased PKM2 and LDHA protein. Based on the models assessed herein, we infer that that FH deficiency compels cells to adopt an early, reversible, and progressive protumorigenic metabolic milieu that is reminiscent of that driving the Warburg effect. Targets identified in these novel and diverse FH-deficient models represent excellent potential candidates for further mechanistic investigation and therapeutic metabolic manipulation in tumors.

Sex steroidal modulation of collagen metabolism in uterine leiomyomas

Uterine leiomyoma is a fibrotic disease that contains abundant extracellular matrix (ECM) components, particularly collagen fibrils. Aberrant ECM metabolism has been thought to contribute to the pathogenesis of uterine leiomyomas. However, it remains poorly understood whether ovarian sex steroid hormones modulate collagen metabolism in uterine leiomyomas. More recently, a few articles have demonstrated the differential effects of ovarian sex steroids, selective estrogen receptor modulators (SERMs), and selective progesterone receptor modulators (SPRMs) on the induction of the ECM-remodeling enzymes and collagen synthesis in uterine leiomyoma cells. Sex steroids may act to up-regulate collagen synthesis, whereas SERMs and SPRMs down-regulate collagen synthesis. Further study will be needed to clarify the precise mechanism underlying steroidal regulation of collagen synthesis in uterine leiomyomas.

Multiple endocrine neoplasia type 1 with multiple leiomyomas linked to a novel mutation in the MEN1 gene

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited syndrome. MEN1 is characterized by the presence of functioning and nonfunctioning tumors or hyperplasia of the pituitary gland, parathyroid glands, and pancreatic islet cells. In addition, MEN1 carriers can have adrenal or thyroid tumors and non-endocrine tumors, such as lipomas, angiofibromas, and leiomyomas. Although leiomyoma is not a major component of MEN1, it is thought to occur more frequently than expected. However, there has been no report of a case of MEN1 with leiomyoma in Korea so far. This report describes a patient with multiple leiomyomas in MEN1. A 50-year-old woman was referred for further evaluation of elevated calcium levels and osteoporosis. Biochemical abnormalities included hypercalcemia with elevated parathyroid hormone. There was hyperprolactinemia with pituitary microadenoma in sella MRI. An abdominal MRI demonstrated adrenal nodules and leiomyomas in the bladder and uterus. Endoscopic ultrasonography demonstrated esophageal leiomyoma and pancreatic islet cell tumor. A subtotal parathyroidectomy with thymectomy was performed. Sequencing of the MEN1 gene in this patient revealed a novel missense mutation (D350V, exon 7). This is the first case of MEN1 accompanied with multiple leiomyomas, parathyroid adenoma, pituitary adenoma, pancreatic tumor, and adrenal tumor.

Expression of sex hormone-binding globulin, oxytocin receptor, caveolin-1 and p21 in leiomyoma

BACKGROUND

Interaction of sex hormone-binding globulin (SHBG) and oxytocin (OT) is among the factors that control smooth muscle proliferation and tumor growth through the oxytocin receptor (OTR). Also, a close functional interaction of OTR and caveolin-1 has been shown to modulate cell growth and proliferation.

METHODS

We studied surgical samples from 23 leiomyoma patients (aged 33-66 years) with immunocytochemistry. Specimens from five patients (34-76 years), who had hysterectomy for other reasons, served as controls. Tissue samples were cut into serial 1-microm thick sections for co-localization of SHBG, OTR, proliferation marker p21 and caveolin-1.

RESULTS

SHBG was found in smooth muscle cells in all samples. OTR staining occurred in most of these cells in myomas, while controls contained only scattered cells positive for OTR. There were no apparent differences in immunostaining for p21, while immunoreactivity for caveolin-1 was observed in most cells in myomas and in only few cells in controls. Caveolin-1 was mostly co-localized with SHBG and OTR in myoma samples whereas controls showed this co-localization only occasionally.

CONCLUSIONS

Our observations indicate an interaction of SHBG and OTR, associated with caveolin-1, which may account in part for known non-genomic actions of ovarian steroids. Growth of leiomyomas may be linked to these mechanisms.

Increased expression of platelet-derived growth factor C messenger ribonucleic acid in uterine leiomyomata

This study was intended to investigate the possible roles of the platelet-derived growth factor (PDGF) gene family's involvement in the pathogenesis of uterine leiomyomata. We examined the differential gene expressions of PDGF-A, -B, -C, -D, PDGF receptor alpha (PDGFR-alpha), and receptor beta (PDGFR-beta) between uterine leiomyomata and the adjacent normal myometrium. Expression of PDGF-C in leiomyomata was significantly higher (approximately 2.4-fold) than in the adjacent normal myometrium, whereas there were no significant differences in the expressions of PDGF-A, -B, -D, PDGFR-alpha, or PDGFR-beta between leiomyomata and the adjacent myometrial tissues.

Regulatory mechanism of Bcl-2 in uterine leiomyomas

Bcl-2 has been thought to play a vital role in the growth of uterine leiomyomas. However, it remains to be fully understood how Bcl-2 expression is regulated in uterine leiomyomas. Several factors have been speculated to affect the induction of Bcl-2 in these cells, including progesterone, endoplasmic reticulum stress, and microRNAs. The elucidation of the regulatory mechanism of Bcl-2 will contribute to a better understanding of the molecular biology of uterine leiomyomas.

Increased HIF1 alpha in SDH and FH deficient tumors does not cause microsatellite instability

Germline mutations in nuclear genes encoding mitochondrial enzymes fumarate hydratase (FH) and succinate dehydrogenase (subunits SDHB/C/D) have been implicated in the development of tumor syndromes referred to as hereditary leiomyomatosis and renal cell cancer (HLRCC) and hereditary paragangliomatosis (HPGL), respectively. FH and SDH are operating in the tricarboxylic acid cycle (the TCA cycle, the Krebs cycle). In the FH and SDH deficient tumors, accumulation of the substrates, fumarate and succinate, has been shown to cause stabilization of hypoxia inducible factor 1 alpha (HIF1 alpha). According to recent studies, HIF1 alpha could contribute to the hypoxia induced genomic instability seen in many cancers, through repression of mismatch repair (MMR) protein MSH2. In this study, in agreement with previous works, we found HIF1 alpha to be moderately or highly stabilized in 67% (16/24) and 77% (48/62) of HLRCC tumors and SDHB/C/D paragangliomas (PGL) and pheochromocytomas (PHEO), respectively. In addition, a set of 54 other familial and nonfamilial PGLs/PHEOs were studied. Moderately or highly stabilized HIF1 alpha was present in 68% (26/38) of the PGLs but in PHEOs (n = 16) no such pattern was observed. We then analyzed the suggested link between HIF1 alpha stabilization and MSH2 repression, in HLRCC and HPGL tumor material. No microsatellite instability (MSI) or lack of MSH2 expression was, however, observed. Thus we failed to provide in vivo evidence for the proposed link between HIF1 alpha stabilization and functional MMR deficiency, in TCAC deficient tumors.

Compensatory alterations in energy homeostasis characterized in uterine tumors from hereditary leiomyomatosis and renal cell cancer

OBJECTIVE

To determine the molecular alterations that maintain energy homeostasis in hereditary leiomyomatosis and renal cell cancer (HLRCC) uterine tumors with disrupted fumarate hydratase, compared with nonsyndromic uterine tumors.

DESIGN

Laboratory study.

SETTING

Tertiary academic university hospital.

PATIENT(S)

Eleven nonsyndromic leiomyoma-myometrium pairs and three HLRCC leiomyoma-myometrium pairs were obtained from patients who were recruited at national and military research centers in the United States.

INTERVENTION(S)

Molecular analysis.

MAIN OUTCOME MEASURE(S)

Hereditary leiomyomatosis and renal cell cancer and nonsyndromic leiomyomas were compared with patient-matched myometrium for relative glycolysis and Krebs cycle gene expression.

RESULT(S)

By microarray analysis, we confirmed that fumarate hydratase messenger RNA (mRNA) was underexpressed in HLRCC fibroids, compared with matched myometrium. Consistent with the possibility that alterations in fumarate hydratase represented a change to a more anaerobic state, we found that HLRCC fibroids overexpressed genes such as phosphofructokinase, aldolase, phosphoglycerate kinase, enolase, and pyruvate kinase. Expression of these genes was not altered in nonsyndromic leiomyomas. Furthermore, there were no overt changes in expression of Krebs cycle enzyme gene expression, with the exception of fumarate hydratase.

CONCLUSION(S)

Our findings demonstrate that alterations in fumarate hydratase are compensated for by increases in glycolysis enzyme expression in HLRCC.

Differential expression of selected gene products in uterine leiomyomata and adenomyosis

Gene products estrogen receptor alpha, progesterone receptor-A, retinoid X receptor alpha, insulin-like growth factor-II, insulin-like growth factor I receptor beta, platelet-derived growth factor, epithelial growth factor receptor, and BCL-2 were examined by immunohistochemistry with the aid of a tissue microarray from 46 hysterectomies with adenomyosis and leiomyomata. With appropriate internal controls, there were significant differences in gene expression between adenomyosis and leiomyomata.

Mechanisms of disease: hereditary leiomyomatosis and renal cell cancer--a distinct form of hereditary kidney cancer

Renal cell carcinoma (RCC) represents a group of diseases linked by their primary site of origin, the kidney. Studies of families with a genetic predisposition to the development of kidney cancer have revealed that multiple genes are involved in the molecular pathogenesis of RCC. Germline mutations in a gene that encodes a Krebs cycle enzyme have been found to result in a distinct clinical entity referred to as hereditary leiomyomatosis and renal cell cancer (HLRCC). HLRCC is inherited in an autosomal-dominant fashion. Affected individuals in HLRCC families are at risk for the development of leiomyomas of the skin and uterus as well as renal cancers. HLRCC-associated kidney tumors are often biologically aggressive. Linkage analysis has identified germline alterations in the fumarate hydratase (FH) gene associated with HLRCC. While the mechanisms of molecular carcinogenesis are not entirely understood, several lines of evidence derived from clinical and basic research suggest that pseudohypoxia might drive cellular transformation. The role of FH mutations in sporadic tumors seems to be limited. Nevertheless, continued investigation of HLRCC should provide further insight into the mechanisms of kidney cancer development, and could potentially identify targets for new therapeutic approaches to RCC.

CD10 in diffuse uterine leiomyomatosis: a case report along with a few comments on histogenesis

Diffuse uterine leiomyomatosis (DUL) is a rare entity with an unknown etiopathogenesis. A 24 years old female presented with abdominal discomfort and menorrhagia. Clinical and ultrasonographic examination revealed an enlarged uterus. The hysterectomy specimen showed a symmetrically enlarged uterus with a bosselated external surface. The cut surface showed multiple nodules of varying sizes diffusely involving the myometrium. Microscopically, the nodules were leiomyomas of varying degrees of cellularity. Some of the leiomyomas showed an increased vascularity either in the form of congeries of blood vessels with a lobular arrangement or occasionally as foci of 2-3 vessels. The vessels were surrounded by whorls of spindle cells. On immunohistochemistry the leiomyomas expressed vimentin, smooth muscle actin (SMA), desmin and CD10: the cells whorling around the blood vessels expressed vimentin, SMA and focally desmin and were negative for CD10 and HMB-45. The aim of this paper is to document that CD10 is expressed in diffuse uterine leiomyomatosis and discuss the histogenesis of DUL.

HIF overexpression correlates with biallelic loss of fumarate hydratase in renal cancer: novel role of fumarate in regulation of HIF stability

Individuals with hemizygous germline fumarate hydratase (FH) mutations are predisposed to renal cancer. These tumors predominantly exhibit functional inactivation of the remaining wild-type allele, implicating FH inactivation as a tumor-promoting event. Hypoxia-inducible factors are expressed in many cancers and are increased in clear cell renal carcinomas. Under normoxia, the HIFs are labile due to VHL-dependent proteasomal degradation, but stabilization occurs under hypoxia due to inactivation of HIF prolyl hydroxylase (HPH), which prevents HIF hydroxylation and VHL recognition. We demonstrate that FH inhibition, together with elevated intracellular fumarate, coincides with HIF upregulation. Further, we show that fumarate acts as a competitive inhibitor of HPH. These data delineate a novel fumarate-dependent pathway for regulating HPH activity and HIF protein levels.

Increased hyaluronan and CD44 expressions in intravenous leiomyomatosis

BACKGROUND

To determine the influence of hyaluronan and its receptor CD44 in the angiogenesis and invasiveness of intravenous leiomyomatosis (IVL).

METHODS

Paraffin-embedded sections from four IVL cases and 10 uterine leiomyoma cases were immunohistochemically stained for CD34, CD44, basic fibroblast growth factor (bFGF), vascular endothelial growth factor, and platelet-derived growth factor and assayed for microvessel densities. Hyaluronan was immunostained by biotinylated hyaluronan-binding peptide and the results were clinically correlated.

RESULTS

CD34 labeling showed significantly increased microvessel counts in IVL (156.6+/-3.7), when compared to uterine leiomyomas (61.3+/-27.3; P<0.001). Hyaluronan and its receptor CD44 were prominently expressed in IVL when compared to leiomyomas and associated with an elevation in bFGF expression.

CONCLUSIONS

IVL is a highly vascular neoplasm with elevated microvessel counts. The increase of hyaluronan and CD44 expression in IVL suggests that it is highly angiogenic and has an invasive potential. Elevation of hyaluronan may play a possible role in the pathogenesis of IVL.

Estrogen and progesterone expression of vessel walls with intravascular leiomyomatosis; discussion of histogenesis

We report seven cases of intravenous leiomyomatosis. Growth beyond the uterus occurred in two of the seven cases in the broad ligament. One 21-year-old patient is one of the youngest reported cases in the literature. Five patients had total abdominal hysterectomy with removal of the adnexa and two patients underwent myomectomy. One of the myomectomy cases had abdominal hysterectomy and bilateral salpingo-oophorectomy one year later due to recurrence. The other one was disease free six months after the operation. Vessel walls harboring intravascular tumor were investigated immunohistochemically for Factor VIII, CD 34, estrogen and progesterone receptors with the hope of making the histogenesis of intravenous leiomyomatosis clear. Immunohistochemical analyses of estrogen receptors, progesterone receptors, vimentin, desmin, smooth muscle actin, CD 10 and h-caldesmon were performed on intravascular tumor cells. Endothelial and subendothelial cells expressed none to scant, very weak progesterone and estrogen receptor positivity. Intravascular tumor cells showed weak (10%) to strong (70%) progesterone receptor positivity and weak (10%) to strong (60%) estrogen receptor positivity. These results do not support the hypothesis of a vessel wall origin for intravenous leiomyomatosis.

Effect of gonadotropin-releasing hormone agonist and medroxyprogesterone acetate on calcium metabolism: a prospective, randomized, double-blind, placebo-controlled, crossover trial

OBJECTIVE

The purpose of this study was to prospectively compare the effectiveness of administering medroxyprogesterone acetate (MPA; 20 mg/d) in either the first (protocol A) or last (protocol B) 12-week period as well as a 6-month course of the GnRH agonist (GnRH-a; leuprolide acetate; 1 mg/d, SC) on calcium (Ca) metabolism.

DESIGN

Prospective, randomized, double-blind, placebo-controlled, crossover trial.

SETTING

Clinical research center, university hospital.

PATIENT(S)

Twenty women were randomized into protocol A or B, received either MPA or placebo along with GnRH-a, and were then crossed over at 12 weeks to placebo or MPA, for the final 12-week interval of GnRH-a therapy.

INTERVENTION(S)

Collection of serum and urine samples and measurement of bone density. Sex hormone, calcitropic hormone, and bone density studies were performed at baseline and at 12 and 24 weeks.

RESULT(S)

In both protocol A and B, LH and E(2) levels declined by 79%-81% and 83%-90% of the baseline, respectively, at 12 and 24 weeks. Serum Ca, phosphorus, alkaline phosphatase, and osteocalcin; 2-h fasting and 24-h urinary Ca excretion; and urinary hydroxyproline levels all increased significantly during GnRH-a treatment alone. Estimated Ca balance decreased significantly during GnRH-a treatment alone. The addition of MPA attenuated the increases in phosphorus, alkaline phosphatase, osteocalcin, and 2-h fasting and 24-h urinary Ca excretion, and the decrease in estimated Ca balance. Comparison of phase order demonstrated that MPA prevented 24-h urinary Ca excretion and urinary hydroxyproline loss and decline in estimated Ca balance when it was added back during the second 12 weeks (protocol B) but not during the first 12 weeks (protocol A). CONCLUSION (S): We conclude that sequential MPA appears to reverse in part the negative effects of GnRH-a on calcitropic hormones and estimated Ca balance.

Benign Metastasizing Leiomyomatosis

The authors report an interesting case of a minimally symptomatic 23-year-old African American woman who was found to have extensive diffuse reticulonodular opacities of the lungs on a routine chest radiograph. She had a hysterectomy 5 years previously for multiple leiomyomas of the uterus. She had no history of any prior exposure to dusts or toxins. Collagen vasculitides and bacterial, mycobacterial, and fungal infectious causes were excluded through standard testing, and a bronchoscopic lung biopsy was nonspecific. An open lung biopsy revealed multiple nodules of proliferating smooth muscle cells intermixed with irregular areas of epithelial-lined spaces. Histologically, the muscle cells appear benign with a very low mitotic rate, and the pathologic findings were consistent with benign metastasizing leiomyomatosis (BML). Staining for estrogen and progesterone receptors, actin, and c-kit were performed. This case and the review of the medical literature support the concept that BML originates from an antecedent leiomyoma of the uterus in virtually all cases with rare exceptions. It appears that tumor metastasizes to lungs or other extrauterine tissues via hematogenous spread. However, the origin of the tumor remains controversial. BML is a rare entity, with only a handful of reports in the medical literature. The authors report an interesting case of BML in a 23-year-old patient who, to their knowledge, is the youngest such patient described and who, at 13 years, has the longest period of clinical follow-up. In this article, the authors review the pathogenesis, cytogenetics, histologic markers, and management options of this rare entity.

Multinodular hydropic leiomyoma of the uterus with perinodular hydropic degeneration and extrauterine extension

Multinodular hydropic leiomyoma (MHL) of the uterus is one of the rarest variants of uterine leiomyomas and can create some diagnostic problems. Only five cases have been reported previously. We describe an MHL with perinodular hydropic degeneration in a 48-year-old woman. Gross examination revealed a large and predominantly intramural, edematous multinodular uterine tumor and extrauterine, small grape-like nodules overlying the lateral surface of the uterine serosa. Histologically, the tumor was composed of extra-intrauterine benign, small smooth muscle nodules with perinodular hydropic degeneration, prominent intramural dissecting growth pattern, and satellite nodules closely resembling vascular invasion. Immunohistochemically, these cells stained for desmin, smooth muscle actin and vimentin. The patient had no evidence of disease for 18 months after hysterectomy. Multinodular hydropic leiomyoma is a clinically benign tumor and should not be confused with intravenous leiomyomatosis and some other unusual leiomyoma variants.

Effect of gonadotropin-releasing hormone agonists on monocyte chemotactic protein-1 production and macrophage infiltration in leiomyomatous uterus

OBJECTIVE

The level of monocyte chemotactic protein-1 (MCP-1), a potent chemoattractant for monocytes, is fivefold higher in myometrium than in leiomyoma. We have previously shown that myometrium from women using GnRH agonists (GnRH-a) express the highest levels of MCP-1, which has antiproliferative effects on leiomyoma cells. We hypothesized that MCP-1 may have a direct paracrine effect in leiomyomatous uterus rather than acting by way of chemoattraction of macrophages.

DESIGN

Cross-sectional study.

SETTING

University medical center.

PATIENT(S)

Women with leiomyoma (n = 32).

INTERVENTION(S)

Immunohistochemical analysis performed in the myometrium and leiomyoma of women receiving (n = 11) and not receiving (n = 21) GnRH-a treatment.

MAIN OUTCOME MEASURE(S)

The MCP-1 levels and macrophage counts determined by immunohistochemistry in the myometrium and leiomyoma of women receiving GnRH-a were compared to the levels and counts in women not receiving GnRH-a.

RESULT(S)

Samples from all 11 patients using GnRH-a revealed strong MCP-1 staining, whereas staining was only weakly present in 11 and absent in 10 samples from patients not receiving GnRH-a, revealing a significant difference in MCP-1 expression between GnRH-a users versus nonusers (P=.006). The number of tissue macrophages between GnRH-a users and nonusers was not significantly different.

CONCLUSION(S)

We found that there is an increase in the MCP-1 protein expression in the myometrium of women receiving GnRH-a treatment. On the other hand, we have not observed a difference in the macrophage count and distribution with GnRH-a treatment, suggesting a potentially direct antiproliferative role for MCP-1 rather than acting by means of chemoattraction of macrophages.

Oestrogen receptor-alpha gene polymorphism is associated with endometriosis, adenomyosis and leiomyomata

Endometriosis, adenomyosis and leiomyomata develop in women of reproductive age and regress after menopause or ovariectomy, suggesting that they grow in an oestrogen-dependent fashion. We investigated whether polymorphism in the oestrogen receptor-alpha (ERalpha) gene is related to oestrogen-dependent benign uterine disease. A total of 203 women with regular menstrual cycles underwent laparotomy or laparoscopy and were diagnosed histologically with endometriosis, adenomyosis and/or leiomyomata. Patients with cervical carcinoma in situ, tubal occlusion or adhesion but no other gynaecological disease were considered to be disease-free. A total of 179 women undergoing annual health examination were grouped as reference population. The distribution of PVUII genotypes (PP, Pp, and pp) of the ERalpha gene was different between each pair of the four groups of endometriosis, adenomyosis/leiomyomata, disease-free, and reference population (P = 0.022-0.0005), except between the former two groups. The PP genotype was less frequent in the groups of endometriosis (P = 0.0002) and adenomyosis/leiomyomata (P = 0.002) as compared to that in the disease-free group. In the endometriosis group, there was no difference in the distribution of PVUII genotypes due to complicating diseases (adenomyosis and/or leiomyomata) or severity of the clinical stages. These results suggest that the PVUII polymorphism of the ERalpha gene is associated with the risk for endometriosis, adenomyosis, and leiomyomata.

Luteinizing hormone receptor expression in leiomyomatosis peritonealis disseminata

BACKGROUND

Leiomyomatosis peritonealis disseminata has been attributed to estrogen stimulation and is seen only rarely in postmenopausal women. In such cases, pathogenesis is uncertain.

CASE

Leiomyomatosis peritonealis disseminata tumors were resected from a postmenopausal woman. She was receiving tamoxifen therapy for breast cancer and had bilateral ovarian Brenner tumors. Estrogen and progesterone receptors were detected. Immunohistochemical analysis indicated that LH receptors were present.

CONCLUSION

Luteinizing hormone receptors were identified in leiomyomatosis peritonealis disseminata in one woman. Levels of FSH and LH increase after menopause, and immunohistochemical analysis showed the presence of LH receptors, so gonadotropin rather than estrogen stimulation might have contributed to development of leiomyomatosis peritonealis disseminata in this uncommon case.

Human uterine leiomyomata express higher levels of peroxisome proliferator-activated receptor gamma, retinoid X receptor alpha, and all-trans retinoic acid than myometrium

Uterine leiomyomata are the main indication for a hysterectomy in the United States and occur in 25% of women >35 years. Because uterine leiomyomata can form when ovariectomized guinea pigs are exposed to estradiol and retinoic acids, we tested whether human leiomyomata had high levels of retinoic acids and related nuclear receptors. Compared with normal human myometrium, leiomyomata had 3- to 5-fold higher levels of peroxisome proliferator-activated receptor gamma (PPARgamma), retinoid X receptor alpha proteins, and all-trans retinoic acid, but only during the follicular phase of the menstrual cycle. 9-cis Retinoic acid was undetectable in either leiomyomata or myometrium. PPARgamma mRNA levels were lower in leiomyomata than myometrium, but only during the luteal phase of the cycle. A PPARgamma agonist, troglitazone, was given to guinea pigs along with estradiol and all-trans retinoic acid and produced the largest leiomyomata seen to date in this model. By contrast, no tumors formed when troglitazone was given alone or with estradiol or when troglitazone was given with estradiol and 9-cis retinoic acid. New therapies for human leiomyomata may emerge by combining antagonists for PPARgamma and retinoid X receptor alpha with selective estrogen receptor modulators.

Multiple pulmonary leiomyomatous hamartoma with secondary ossification

A 31-year-old woman presented with multiple pulmonary leiomyomatous hamartoma (MPLH) with secondary ossification. She had a past history of parosteal osteosarcoma. The pulmonary lesions were composed of spindle-shaped cells arranged in interlacing fascicles, among which glands or duct-like spaces were scattered. As some lesions contained bony tissues, it was unclear whether or not the pulmonary lesions were metastases of parosteal osteosarcoma. However, the majority of spindle-shaped cells were positive for alpha-smooth muscle actin, including cells proliferating around the bony tissues. Clonality analysis using a target of human androgen receptor (HUMARA) gene disclosed that the pulmonary nodules were polyclonal. These findings do not indicate that the lesions were metastatic. We would like to emphasize that MPLH can show osseous metaplasia.

Expression and hormonal regulation of monocyte chemotactic protein-1 in myometrium and leiomyomata

OBJECTIVE

The pathogenesis of leiomyoma likely involves interactions of sex steroids with paracrine growth factors or cytokines resulting in modulation of local immunity. Monocyte chemotactic protein-1 (MCP-1) is a chemotactic and activating factor for monocytes and is produced by multiple tumors and has antitumor effects. We investigated the expression of MCP-I in leiomyoma and myometrium as well as the regulatory role of steroid hormones and cytokines on MCP-1 expression and the effect of MCP-1 on the proliferation of leiomyoma cells.

DESIGN

Prospective study.

SETTING

University medical center.

PATIENT(S)

Women with (n = 20) or without (n = 11) leiomyoma.

INTERVENTION(S)

First. MCP-1 messenger RNA (mRNA) levels in myometrium and leiomyoma were measured, and then myometrial and leiomyoma cells in culture were treated with steroid hormones and cytokines.

MAIN OUTCOME MEASURE(S)

The MCP-1 mRNA was evaluated by Northern analysis. Immunoreactive MCP-1 in cell cultures was quantified by ELISA. Leiomyoma cell proliferation was assessed with [3H]thymidine incorporation.

RESULT(S)

The MCP-1 mRNA levels in myometrial samples were 4.7-fold higher than in the leiomyoma samples. Myometrial MCP-1 mRNA levels were 2.4-fold higher in secretory than in proliferative phase samples. The highest MCP-1 levels were observed in samples from women using GnRH analogues. Estradiol and progestins, alone or in combination, resulted in a decrease in MCP-1 protein production. There was an increase in the proliferation of leiomyoma cells treated with anti-MCP-1 neutralizing antibody.

CONCLUSION(S)

These findings suggest that MCP-1 may have antineoplastic activity in leiomyomata and that sex steroids may be exerting their growth stimulatory effect in leiomyomata through down-regulation of MCP-1.

Organization and expression of basement membrane collagen IV genes and their roles in human disorders

Six distinct genes have been identified as belonging to the type IV collagen gene family. They can be organized into three sets, i.e., COL4A1/COL4A2, COL4A3/COL4A4, and COL4A5/COL4A6, which are localized on three different chromosomes in humans, 13, 2, and X, respectively. Within each set the genes are aligned head-to-head and their expression is regulated by bidirectional promoters between the genes. Transcriptional regulation of the COL4A1/COL4A2 set has been well characterized. The transcription of COL4A6 seems to be controlled by two alternative promoters. While collagen IV molecules composed of alpha1 and alpha2 chains are broadly distributed, molecules comprising combinations of the other four chains, alpha3-alpha6, are important components of specialized basement membranes. The precise chain composition of triple-helical molecules assembled from the alpha3-alpha6 chains is not entirely clear, but it is hypothesized that alpha3-alpha5 chains and alpha5 and alpha6 chains form heterotrimeric molecules. Several pieces of evidence indicate that alpha3/alpha4/alpha5 molecules and alpha5/alpha6 molecules are components of the basement membrane network. This helps explain the observation that the kidney and skin basement membranes from patients with Alport syndrome caused by mutations in the alpha5 coding gene, COL4A5, are defective in the alpha3, alpha4, and alpha6 chains together with the alpha5 chain. Large deletions involving the COL4A5 and COL4A6 genes have been found in rare cases of diffuse leiomyomatosis associated with Alport syndrome.

Diffuse leiomyomatosis associated with X-linked Alport syndrome: extracellular matrix study using immunohistochemistry and in situ hybridization

Inherited diffuse esophageal leiomyomatosis a benign tumor involving smooth muscle cells of the whole esophagus, is frequently associated with X-linked Alport syndrome, a hereditary disease of type IV collagen. Families with this condition are consistently found to have deletions encompassing the 5' ends of both the alpha 5 chain of type IV collagen (COL4A5) and the alpha 6 chain of type IV collagen (COL4A6) genes, always limited in COL4A6 to exons 1', 1, and 2. On the contrary, patients with COL4A5/COL4A6 deletions extending further into COL4A6 display no such tumors. Despite the deletion, a COL4A6 transcript including exon 4, but not exon 3, was found in a tumor sample, raising the possibility of the involvement of a truncated alpha 6(IV) chain in the tumorous process. Using immunohistochemistry and in situ hybridization methods, we analyzed the expression and distribution of the alpha 6 chain of type IV collagen in tumors in comparison with that of normal, fetal, and mature esophagus. We also studied associated changes in tumor basement membrane composition and in tumor-cell integrin subunit distribution. No labeling with alpha 6(IV) antibodies was detected in tumors, ruling out the hypothesis of a stably integrated truncated alpha 6(IV) chain in tumor basement membranes. In contrast, despite the deletions of the first two exons of the gene and its 5' end, a COL4A6 transcript is clearly expressed by tumor cells. This finding raises the question of a potential role for this RNA in the tumor process. The absence of the alpha 6(IV) chain is associated with the absence of the alpha 5(IV) chain, as was suggested by the COL4A5 deletion. An additional striking feature is the absence of the beta 1 chain of laminin in tumor basement membranes and the lack of or uneven expression of the alpha 5 integrin subunit. These findings show that dramatic changes in the composition of the matrix and the expression of integrin receptors also occur in this benign tumorous process.

[Uterine fibromas and the hormonal pattern: the therapeutic considerations]

Uterine fibromyomatosis is a widely recognised and well studied pathology that is found in around 30% of over 35-year-old women. It has been extensively demonstrated that the etiology of fibromyomas is hormone dependent and to date the main pathogenetic role in the development of these benign tumours has largely been attributed to estrogens. Uterine fibromyomas have been found to contain a higher level of estrogen and progesterone receptors than in normal uterus. This suggests an etiopathogenetic role also for progesterone, which is confirmed by the higher mitotic index of myomatous tissue cells in luteal phase. Growth factors also seem to be involved in the origin of uterine fibromyomatosis: concentrations of epidermal growth factor (EGF), insulin like growth factor 1 (IGF-I) and platelet derived growth factor (PDGF AB) are present in myomatous tissues together with their receptors. Recent studies have shown that the administration of an anti-progestin compound, like RU 486, causes a reduction in fibromyoma size. The role of progesterone in promoting uterine growth opens new horizons in the treatment of uterine fibromyomatosis. Treatment with GnRH analogs has proved effective in reducing the size of fibromyomas, even if the problem of their regrowth once treatment has been suspended remains unsolved. The administration of 100 mg of danazol for 6 months after treatment using GnRH analogs reduce fibromyoma rebound growth by around 30%.

Gastroesophageal-vulvar leiomyomatosis presenting over the course of 20 years

Gastroesophageal-vulvar leiomyomatosis represents a rare syndrome of diffuse smooth muscle proliferation primarily in the gastroesophagus and vulva. To our knowledge, there are 19 cases reported in the literature, most associated with Alport's syndrome. We recently encountered a case not associated with Alport's syndrome, which had progressed over the course of 20 years. We used immunohistochemistry to further delineate the process. Leiomyomatosis appears to be a systemic disorder, with indolent proliferations of smooth muscle in areas that may not be clinically significant.

Disseminated peritoneal leiomyomatosis. An unusual case

Disseminated peritoneal leiomyomatosis (DPL) is a very rare disorder, characterized by the presence of multiple intraabdominal smooth muscle nodules and frequently associated with a high estrogen production. We report on a 43-year-old woman with DPL and simultaneous bilateral ovarian cystic teratomas. There were no overt endocrine abnormalities. Due to distinct cellular pleomorphism on a frozen section, complete removal of smooth muscle nodules was suggested, but could not be achieved because of severe bleeding. Two years after resection of the ovarian tumors but with residual DPL, the patient is doing well, with no evidence of malignant disease.