OBJECTIVE

ALK FISH analysis is used as the reference standard to demonstrate ALK rearrangements, which qualify patients with pulmonary adenocarcinomas for therapy with ALK inhibitors. The aim of this study was to find screening ALK antibody clones with the best positive and best negative percentage agreement with ALK FISH.

RESULTS

Three hundred and three pulmonary adenocarcinomas were evaluated with ALK FISH and stained with five ALK antibody clones (5A4; D5F3; ALK1; ALK01; SP8) with standardized detection systems. D5F3 was additionally assessed using the OptiView enhanced detection and amplification system. ALK FISH found 14 cases (4.6%) that harboured ALK rearrangements. These stained at all intensities for D5F3 and 5A4. To identify rearranged cases among stained cases, we subsequently analysed all immunohistochemically positive cases with ALK FISH.

CONCLUSIONS

D5F3 with OptiView exclusively stained rearranged cases with strong intensity, without a single false-positive or false-negative case. The number of subsequent ALK FISH analyses required would have decreased from 303 to 14 cases (-95.4%), reducing significantly the time, work and costs without any loss of diagnostic quality and accuracy.

This paper concentrates on the genetic aspects of pulmonary arterial hypertension (PAH), a diagnostically based subclass of pulmonary hypertension that includes primary pulmonary hypertension (PPH). During the past year, patients with familial and sporadic PPH were found to have germline heterozygous missense, nonsense and frameshift mutations in bone morphogenetic protein receptor II (BMPR2). Mutations in BMPR2, a member of the transforming growth factor-beta (TGF-beta) receptor superfamily, are predicted to interrupt the bone morphogenetic protein (BMP) signalling pathway, resulting in proliferation, rather than apoptosis of cells within small arterioles. Mechanistically, haploinsufficiency was found by using in vitro gene expression experiments, but a dominant-negative mechanism has not been excluded. The failure to find BMPR2 mutations in all families with familial PPH and in all patients with sporadic PPH suggests that other genes remain to be identified. Mutations in ALK1, a TGF-beta type 1 receptor, previously known to cause type 2 hereditary haemorrhagic telangiectasia (HHT), have also been reported in a few HHT families with clinical and histological features of PPH. The clinical development of PPH, as in neoplasia, appears to require 'two hits' The two hits can be provided either by genetic or environmental factors.

OBJECTIVE

To determine if patients with hereditary hemorrhagic telangiectasia (HHT) show alterations in transforming growth factor (TGF)-beta and its pathways.

METHODS

Blood samples were obtained from HHT patients and controls, while endothelial cells were derived from umbilical veins of newborns (HUVEC) from HHT families. TGF-beta1 in plasma, or secreted by HUVEC, and plasma endoglin levels were measured by ELISA. Cellular levels of endoglin and receptor Smad proteins were tested by metabolic labeling and immunoprecipitation, mRNA levels for endoglin and TGF-beta1 by real-time PCR, and receptor Smad phosphorylation by Western blotting.

RESULTS

TGF-beta1 and endoglin plasma levels analyzed in 197 individuals showed an inverse correlation with age. Circulating levels of TGF-beta1 were reduced in HHT1 patients (with Endoglin mutations) compared to control, but not in HHT2 patients (with ALK1 mutations). Endoglin levels were unchanged in plasma but decreased in activated monocytes and HUVEC with an HHT1 genotype. These HUVEC also expressed reduced levels of endoglin and TGF-beta1 mRNA, secreted less TGF-beta1, and showed normal receptor Smad expression and phosphorylation.

CONCLUSIONS

Decreased plasma TGF-beta1 levels in HHT1 patients correlate with reduced production by endothelial cells. The lower endoglin expression in these cells may alter the regulation of TGF-beta1 via Smad-independent pathways.

GDF8, or myostatin, is a member of the TGF-β superfamily of secreted polypeptide growth factors. GDF8 is a potent negative regulator of myogenesis both in vivo and in vitro. We found that GDF8 signaling was inhibited by the small molecule ATP competitive inhibitors dorsomorphin and LDN-193189. These compounds were previously shown to be potent inhibitors of BMP signaling by binding to the BMP type I receptors ALK1/2/3/6. We present the crystal structure of the type II receptor ActRIIA with dorsomorphin and demonstrate that dorsomorphin or LDN-193189 target GDF8 induced Smad2/3 signaling and repression of myogenic transcription factors. As a result, both inhibitors rescued myogenesis in myoblasts treated with GDF8. As revealed by quantitative live cell microscopy, treatment with dorsomorphin or LDN-193189 promoted the contractile activity of myotubular networks in vitro. We therefore suggest these inhibitors as suitable tools to promote functional myogenesis.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by arteriovenous malformations and hemorrhages. This vascular disease results mainly from mutations in 2 genes involved in the TGF-β pathway (ENG and ALK1) that are exclusively expressed by endothelial cells. The present study identified miR-27a and miR-205 as two circulating miRNAs differentially expressed in HHT patients. The plasma levels of miR-27a are elevated while those of miR-205 are reduced in both HHT1 and HHT2 patients compared to healthy controls. The role of miR-205 in endothelial cells was further investigated. Our data indicates that miR-205 expression displaces the TGF-β balance towards the anti-angiogenic side by targeting Smad1 and Smad4. In line, overexpression of miR-205 in endothelial cells reduces proliferation, migration and tube formation while its inhibition shows opposite effects. This study not only suggests that detection of circulating miRNA (miR-27a and miR-205) could help for the screening of HHT patients but also provides a functional link between the deregulated expression of miR-205 and the HHT phenotype.

NPM-ALK chimeric transcripts, encoded by the t(2;5), lead to an aberrant expression of ALK by CD30+ systemic lymphomas. To determine if t(2;5) is involved in cutaneous lymphoproliferative disorders, we studied 37 CD30+ cutaneous lymphoproliferations, 27 mycosis fungoides (MF), and 16 benign inflammatory disorders (BID). NPM-ALK transcripts were detected by nested reverse transcription-polymerase chain reaction (RT-PCR) in 1 of 11 lymphomatoid papulosis (LyP), 7 of 15 CD30+ primary cutaneous T-cell lymphoma (CTCL), 3 of 11 CD30+ secondary cutaneous lymphoma, 6 of 27 MF, and 1 of 16 BID. However, the expression of NPM-ALK transcripts was not associated with ALK1 immunoreactivity in MF, LyP, or BID cases. Only 1 CD30+ primary CTCL and 3 CD30+ secondary cutaneous lymphoma were ALK1 immunoreactive. The ALK1+ cases were also characterized by amplification of tumor-specific genomic breakpoints on derivative chromosome 5. These cases, except for 1 secondary cutaneous lymphoma, were also characterized by reciprocal breakpoints on derivative chromosome 2, leading to the expression of reciprocal ALK-NPM transcripts. Amplification of chromosomal breakpoints on both derivative chromosomes could represent an alternative to conventional cytogenetics for the diagnosis of t(2;5) and seems to be more reliable than the detection of cryptic NPM-ALK transcripts by nested RT-PCR.

BACKGROUND

Detection of the ALK rearrangement in a solid tumor gives these patients the option of crizotinib as an oral form of anticancer treatment. The current test of choice is fluorescence in situ hybridization (FISH), but various cheaper and more convenient immunohistochemical (IHC) assays have been proposed as alternatives.

METHODS

Fifteen FISH-positive cases from patients, seven with data on crizotinib therapy and clinical response, were evaluated for the presence of ALK protein using three different commercially available antibodies: D5F3, using the proprietary automated system (Ventana), ALK1 (Dako), and 5A4 (Abcam). A further 14 FISH-negative and three uncertain (<15% rearrangement detected) cases were also retrieved. Of the total 32 specimens, 17 were excisions and 15 were computed tomography-guided biopsies or cytological specimens. All three antibodies were applied to all cases. Antibodies were semiquantitatively scored on intensity, and the proportion of malignant cells stained was documented. Cutoffs were set by receiver operating curve analysis for positivity to optimize correct classification.

RESULTS

All three IHC assays were 100% specific but sensitivity did vary: D5F3 86%, ALK 79%, 5A4 71%. Intensity was the most discriminating measure overall, with a combination of proportion and intensity not improving the test. No FISH-negative IHC-positive cases were seen. Two FISH-positive cases were negative with all three IHC assays. One of these had been treated with crizotinib and had failed to show clinical response. The other harbored a second driving mutation in the EGFR gene.

CONCLUSIONS

IHC with all three antibodies is especially highly specific (100%) although variably sensitive (71%-86%), specifically in cases with scanty material. D5F3 assay was most sensitive in these latter cases. Occasional cases are IHC-positive but FISH-negative, suggesting either inaccuracy of one assay or occasional tumors with ALK rearrangement that do not express high levels of ALK protein.

BACKGROUND

Activin receptor-like kinase 1 (ALK1) is a Transforming Growth Factor-beta (TGF-beta) receptor type I, mainly expressed in endothelial cells that plays a pivotal role in vascular remodelling and angiogenesis. Mutations in the ALK1 gene (ACVRL1) give rise to Hereditary Haemorrhagic Telangiectasia, a dominant autosomal vascular dysplasia caused by a haploinsufficiency mechanism. In spite of its patho-physiological relevance, little is known about the transcriptional regulation of ACVRL1. Here, we have studied the different origins of ACVRL1 transcription, we have analyzed in silico its 5'-proximal promoter sequence and we have characterized the role of Sp1 in the transcriptional regulation of ACVRL1.

RESULTS

We have performed a 5'Rapid Amplification of cDNA Ends (5'RACE) of ACVRL1 transcripts, finding two new transcriptional origins, upstream of the one previously described, that give rise to a new exon undiscovered to date. The 5'-proximal promoter region of ACVRL1 (-1,035/+210) was analyzed in silico, finding that it lacks TATA/CAAT boxes, but contains a remarkably high number of GC-rich Sp1 consensus sites. In cells lacking Sp1, ACVRL1 promoter reporters did not present any significant transcriptional activity, whereas increasing concentrations of Sp1 triggered a dose-dependent stimulation of its transcription. Moreover, silencing Sp1 in HEK293T cells resulted in a marked decrease of ACVRL1 transcriptional activity. Chromatin immunoprecipitation assays demonstrated multiple Sp1 binding sites along the proximal promoter region of ACVRL1 in endothelial cells. Furthermore, demethylation of CpG islands, led to an increase in ACVRL1 transcription, whereas in vitro hypermethylation resulted in the abolishment of Sp1-dependent transcriptional activation of ACVRL1.

CONCLUSIONS

Our results describe two new transcriptional start sites in ACVRL1 gene, and indicate that Sp1 is a key regulator of ACVRL1 transcription, providing new insights into the molecular mechanisms that contribute to the expression of ACVRL1 gene. Moreover, our data show that the methylation status of CpG islands markedly modulates the Sp1 regulation of ACVRL1 gene transcriptional activity.

BACKGROUND

Formation of blood vessels from pre-existing ones, also termed angiogenesis, is of crucial importance for the outgrowth of tumours beyond 1 - 2 mm³. Therefore, anti-angiogenic therapies, mainly focussing on inhibition of vascular endothelial growth factor (VEGF) are used in clinical therapy. However, although initially reducing tumour size, therapy resistance occurs frequently and new targets are needed. A possible target is activin receptor-like kinase (ALK)-1, a transforming growth factor (TGF)-β type-I receptor, which binds bone morphogenetic protein (BMP)-9 and -10 with high affinity and has an important role in regulating angiogenesis.

METHODS

Several approaches to interfere with ALK1 signalling have been developed, that is, ALK1 neutralising antibodies and a soluble ALK1 extracellular domain/Fc fusion protein (ALK1-Fc), acting as a ligand trap. In this review, we discuss the involvement of ALK1 in angiogenesis, in a variety of diseases and the current status of the development of ALK1 inhibitors for cancer therapy.

CONCLUSIONS

Based on current, mainly preclinical studies on inhibition of ALK1 signalling by ligand traps and neutralising antibodies, targeting ALK1 seems very promising. Both ALK1-Fc and neutralising antibodies strongly inhibit angiogenesis in vitro and in vivo. The results from the first Phase I clinical trials are to be reported soon and multiple Phase II studies are ongoing.

In humans and animals lacking functional LDL receptor (LDLR), LDL from plasma still readily traverses the endothelium. To identify the pathways of LDL uptake, a genome-wide RNAi screen was performed in endothelial cells and cross-referenced with GWAS-data sets. Here we show that the activin-like kinase 1 (ALK1) mediates LDL uptake into endothelial cells. ALK1 binds LDL with lower affinity than LDLR and saturates only at hypercholesterolemic concentrations. ALK1 mediates uptake of LDL into endothelial cells via an unusual endocytic pathway that diverts the ligand from lysosomal degradation and promotes LDL transcytosis. The endothelium-specific genetic ablation of Alk1 in Ldlr-KO animals leads to less LDL uptake into the aortic endothelium, showing its physiological role in endothelial lipoprotein metabolism. In summary, identification of pathways mediating LDLR-independent uptake of LDL may provide unique opportunities to block the initiation of LDL accumulation in the vessel wall or augment hepatic LDLR-dependent clearance of LDL.

This retrospective study evaluated 15 cases of inflammatory myofibroblastic tumours (IMTs) to determine histological atypicality, clinicopathological features, outcomes, and expression of anaplastic lymphoma kinase-1 (ALK1) and p53, to assess potential pathological prognostic indicators. Nine patients with complete follow-up had no evidence of recurrence, including two with recurrent disease who were treated with additional surgery. Six patients had local recurrence and distant metastasis. Six (40.0%) tumours showed cellular atypicality. Significant correlations were found between histological atypicality and recurrence and metastasis. Recurrence was documented in 25.0% of ALK-positive and 63.6% ALK-negative IMTs, whereas metastasis was confined to the ALK-negative group. Recurrence and metastasis were documented in 50.0% and 25.0% of p53-positive IMTs, respectively, and in 57.1% and 57.1%, respectively, of the p53-negative IMTs. The IMT cases had high recurrence and metastasis and there were significant correlations between histological atypicality and recurrence and metastases, and between absence of ALK reactivity and recurrence. No correlation was found between p53 expression and any clinicopathological feature of IMT.

We have previously demonstrated that activin is likely an ovarian mediator of pituitary gonadotropin(s) and local epidermal growth factor in their stimulating oocyte maturation and maturational competence in the zebrafish. However, the downstream events controlled by activin remain unknown. One possible mechanism is that activin may directly work on the oocytes to promote the development of oocyte maturational competence. To substantiate this hypothesis, we performed the present study to demonstrate the expression of the activin system in different compartments of zebrafish follicles, namely, the follicle cells and oocytes. The proteins examined include activin subunits (betaA and betaB), activin-binding protein (follistatin), activin type II receptors (type IIA and IIB), the type I activin receptor-like kinases (ALK1-like, ALK2-like, and ALK4-like), and the intracellular activin signaling molecules (Smad2, Smad3, Smad4, and Smad7). The results showed that the entire activin signaling system is expressed by the full-grown immature zebrafish oocytes ( approximately 0.65 mm in diameter), including ALK4-like (ActRIB), ALK2-like (ActRIA), ActRIIA, ActRIIB, Smad2, Smad3, Smad4, and Smad7, therefore supporting our hypothesis that the oocytes are one of the direct targets of activin actions in the zebrafish ovary. In contrast, activin itself (betaA and betaB) and ALK1-like type I receptor are predominantly expressed in the follicle cells surrounding the oocytes. Interestingly, although follistatin is expressed in both the follicle cells and oocytes, its level of expression is significantly higher in the oocytes than the follicle cells, implying that follistatin may serve as a signal from the oocytes to modulate the activity of activin produced by the follicle cells. Taken together, the present study provides convincing evidence that although all members of the activin system are expressed in the whole follicle, they exhibit distinct spatial patterns of expression among different compartments of the follicle. It is likely that activin works directly on the oocytes in a paracrine manner to promote oocyte maturation and maturational competence. On the other hand, instead of being controlled passively by the follicle cells, the oocytes may actively participate in the regulation of follicle development by releasing various modulating molecules such as follistatin.

A second alkane-inducible cytochrome P450-encoding gene (CYP52A2) from the yeast Candida tropicalis was sequenced and characterized. CYP52A2 is located 1 kb upstream from CYP52A1, the previously characterized P450 gene [Sanglard and Loper, Gene 76 (1989) 121-136] and shows the same orientation. Like CYP52A1, CYP52A2 is induced by growth on alkane. Both promoter regions share repeats of the sequence CATGTGAA that could be of importance for the induction of the two genes. At the amino acid level, alk2 shows an overall identity of 68.2% and an overall similarity of 81.6% to alk1. Regions of high homology between the two proteins are found in the distal and proximal heme binding sites which contain the highly conserved cysteine residue as the fifth ligand to the heme iron. However, marked differences between the two proteins exist at their N-terminal end, which includes the transmembrane domain, and at the putative substrate-binding domain. Upon expression of CYP52A2 in Saccharomyces cerevisiae, alk2 was shown to hydroxylate hexadecane, but had no hydroxylation activity towards lauric acid, whereas alk1 showed both activities. Comparative immunoblots demonstrate that neither alk1 nor alk2 expressed in S. cerevisiae corresponds to the main cytochrome P450 present in C. tropicalis when grown on alkane.

Understanding the interactions between growth factors and bone morphogenic proteins (BMPs) signaling remains a crucial issue to optimize the use of mesenchymal stem cells (MSCs) and BMPs in bone tissue engineering. BMP9 is highly capable of promoting osteogenic differentiation of MSCs. Fibroblast growth factor 2 (FGF2) is abundantly secreted during the healing process of fractures or in surgery bone sites. Herein, we explore the detail effect of FGF2 on BMP9-induced osteogenic differentiation of MSCs. It was found that FGF2 inhibited BMP9-induced osteogenic differentiation by blocking BMP9-induced Smads signaling and subsequently reducing Smads dependent up-regulation of ALK1 and ALK2 in MSCs. This effect was rescued by exogenous expression of ALK1 and ALK2, which are proved to be receptors for BMP9. Our results discovered a clue to explain the mechanism involved in the inhibitory effect of FGF2 on BMP9-induced osteogenic differentiation of MSCs. This crosstalk between FGF2 and BMP9 should be emphasized in the future use of BMP9 in therapeutic purpose of fracture repair.

Genetic mutation or loss of activin/transforming growth factor-beta (TGFbeta) receptor function has been shown in human lymphoid, breast, and colorectal tumors as well as Hep2B and Mv1Lu cell lines. Although activin stimulates FSHbeta biosynthesis and secretion, a large percentage of human gonadotroph tumors have previously been demonstrated to be nonresponsive to characterized activin effects. This phenotype may be indicative of loss of functional cell surface receptors and/or intracellular signaling mediators of activin responses. Several studies examining the structure/function of type I and II receptors specific for ligands in the TGFbeta superfamily have delineated the critical regions for receptor intracellular kinase function. In the case of TGFbeta, inactivating mutations in these regions have been shown to render these receptors kinase deficient by a dominant negative phenotype and result in resistance to growth arrest. We therefore hypothesized that activin/TGFbeta cell surface receptors may act as tumor suppressors in human pituitary tumors, and that inactivating genetic mutations in the intracellular kinase region of this gene family may release pituicytes from normal growth suppression by activin through a similar mechanism. We used single stranded conformational polymorphism analysis to examine 2 intracellular regions required for type I receptor signaling by human Alk1-5 type I receptors as well as the entire coding region of 2 activin type II receptors and the TGFbeta type II receptor in 64 human pituitary tumors. A novel polymorphism was found in 45% of tumors at codon P117 of the ActRIIA gene and was used as a positive control for single stranded conformational polymorphism. One patient with a gonadotroph tumor had a confirmed A482V germline mutation in the Alk1 gene within kinase subdomains X-XI. No other mutations were detected in any tumor studied. These data suggest that somatic mutations within these intracellular kinase regions of type I/type II receptors are rare in human pituitary tumors.

Between 1987 and 1993, 77 of 2855 lymphomas included in the LNH87 protocol of the GELA as non-Hodgkin lymphoma (NHL) and reviewed by a panel of pathologists had a diagnosis changed to Hodgkin lymphoma (HL). Some of these lymphomas had been initially interpreted as anaplastic large-cell lymphoma Hodgkin-like (ALCL-HL subtype). The purpose of this study was to analyze the histologic pitfalls initially encountered, to define more clearly the diagnostic criteria of lymphomas placed in the gray zone around HL, and to follow the survival of these 77 patients affected with HL and initially treated with NHL regimens. The 77 cases of HL were reviewed by three hematopathologists and immunostained with a large panel of antibodies, including CD30, CD15, CD3, CD20, CD45, CD43, LMP-1, EMA, BNH-9, TiA1, and ALK1. Each case was classified according to the Lukes-Rye system and the British National Lymphoma Investigation (BNLI) grading. The initial clinical presentation of patients was analyzed, and the overall and event-free survival rates of the 77 patients were estimated. Among the 77 HLs, 46 were misinterpreted as NHL by primary individual pathologists (12 as ALCL, 8 as ALCL-HL, 12 as peripheral T-cell lymphoma (PTCL), 6 as B-cell lymphoma, and 8 as unclassifiable NHL). The other 31 cases had been first considered by the panel as consistent with ALCL-HL (n = 18) or with PTCL (n = 13) and were changed later in view of an immunophenotype concordant with HL. Fifty-five percent of the patients completed the full NHL treatment. The 5-year event-free and overall survival rates were 54% and 77%, respectively. The current results indicate that lymphomas initially called ALCL-HL should not be regarded as a variant of ALCL, but as HL. The clinical consequences of misdiagnoses seem to be a lower event-free survival rate compared with that of classical HL, probably because of more relapses of initially inappropriately treated HL.

Hereditary hemorrhagic telangiectasia (HHT), or Osler-Rendu-Weber syndrome, is a heterogeneous inherited disorder characterized by multi-systemic vascular dysplasia and wide variation in its phenotypic expression. Hepatic manifestation is seen in about 8 to 30 % of the patients. The molecular basis for liver involvement is unknown. We screened the two known HHT disease loci, the ALK1 (ACVRL1) and ENG genes, for mutations in a clinically well-characterized group of HHT patients with or without liver involvement. Mutations in the ALK1 gene were detected in eight out of 10 HHT patients with hepatic manifestation. Among nine HHT patients without liver involvement, four had mutations in the ALK1, and three in the ENG genes, respectively. In one patient with hepatic manifestation a mutation was detected in both the ALK1 and ENG genes. No mutation could be detected in two patients with liver involvement and, likewise, in two patients without hepatic manifestation. In this study, we have identified five novel ALK1 and one ENG disease-causing mutations. We conclude that hepatic manifestation in HHT patients is associated with mutations in the ALK1 gene, but rarely with ENG mutations.

CEMIP (for "Cell migration-inducing protein" also called KIAA1199 and Hybid for "Hyaluronan-binding protein") expression is increased in cancers and described as a regulator of cell survival, growth and invasion. In rheumatoid arthritis, CEMIP is referred to as an angiogenic marker and participates in hyaluronic acid degradation. In this study, CEMIP expression is investigated in healthy and osteoarthritis (OA) cartilage from human and mouse. Its role in OA physiopathology is deciphered, specifically in chondrocytes proliferation and dedifferentiation and in the extracellular matrix remodeling. To this end, CEMIP, αSMA and types I and III collagen expressions were assessed in human OA and non-OA cartilage. CEMIP expression was also investigated in a mouse OA model. CEMIP expression was studied in vitro using a chondrocyte dedifferentiation model. High-throughput RNA sequencing was performed on chondrocytes after CEMIP silencing. Results showed that CEMIP was overexpressed in human and murine OA cartilage and along chondrocytes dedifferentiation. Most of genes deregulated in CEMIP-depleted cells were involved in cartilage turnover (e.g., collagens), mesenchymal transition and fibrosis. CEMIP regulated β-catenin protein level. Moreover, CEMIP was essential for chondrocytes proliferation and promoted αSMA expression, a fibrosis marker, and TGFβ signaling towards the p-Smad2/3 (Alk5/PAI-1) pathway. Interestingly, CEMIP was induced by the pSmad1/5 (Alk1) pathway. αSMA and type III collagen expressions were overexpressed in human OA cartilage and along chondrocytes dedifferentiation. Finally, CEMIP was co-expressed in situ with αSMA in all OA cartilage layers. In conclusion, CEMIP was sharply overexpressed in human and mouse OA cartilage and along chondrocytes dedifferentiation. CEMIP-regulated transdifferentiation of chondrocytes into "chondro-myo-fibroblasts" expressing α-SMA and type III collagen, two fibrosis markers. Moreover, these "chondro-myo-fibroblasts" were found in OA cartilage but not in healthy cartilage.

Lung adenocarcinoma is characterized by marked heterogeneity and may be composed of an admixture of histologic growth patterns, including acinar, papillary, solid, and lepidic (bronchioloalveolar). Tumors displaying a prominent or predominant cribriform architecture are rare and most often confused for metastases from other organs. We report the clinical, histologic, immunohistochemical, and molecular features in 15 primary lung adenocarcinomas with a predominant cribriform histology. All patients were adults between 30 and 80 years of age (median: 64), and all but one reported a history of heavy cigarette smoking. All cases showed a predominant (>70%) cribriform architecture that resembled a variety of tumors arising in other organs, including breast, prostate, ovary, pancreas, uterus, colon, and thyroid. Immunohistochemical stains showed a phenotype consistent with a primary lung tumor (ie, TTF1+/CK7+), with negative results for other markers. Molecular analysis in six cases showed that none harbored an EGFR-activating mutation. KRAS mutation was detected in one case, and an ALK1 and ROS1 gene rearrangement were each detected in an additional two cases. Cribriform adenocarcinomas of the lung represent a distinctive histologic subtype of lung cancer that may be morphologically difficult to differentiate from metastases with a predominant cribriform architecture.

Haspin is a protein kinase identified in mouse and human cells, and genes coding for haspin-like proteins are present in virtually all eukaryotic genomes sequenced so far. Two haspin homologues, called Alk1 and Alk2, are present in the yeast Saccharomyces cerevisiae. Both Alk1 and Alk2 exhibit a weak auto-kinase activity in vitro, are phosphoproteins in vivo and are hyperphosphorylated in response to DNA damage. The amount and modification of the two proteins is greatly regulated during the cell cycle. In fact, Alk1 and Alk2 levels peak in mitosis and late-S/G2, respectively, and phosphorylation of both proteins is maximal in mitosis. Control of protein stability plays a major role in Alk2 regulation. The half-life of Alk2 is particularly short in G1; mutagenesis and genetic analysis indicate that its degradation is controlled by the APC pathway. Overexpression of ALK2, but not of ALK1, causes a mitotic arrest, which is correlated to the kinase activity of the protein. This finding, together with its cell cycle regulation, suggests a role for Alk2 in the control of mitosis.

True histiocytic lymphoma, as defined by strict criteria, is a very rare neoplasm. We describe three cases occurring as primary tumors in the central nervous system. The patients, two females and one male, ranged in age from 11 to 69 years. The tumors involved the brain in two cases and spinal cord in one, with a size ranging from 7 to 17 mm. Two patients died at 4 months and 8 months, respectively, and one was alive with disease at 5 months. Pathologically, the tumors comprised groups and sheets of noncohesive large cells with pleomorphic vesicular nuclei, distinct nucleoli, and abundant eosinophilic cytoplasm. A dense inflammatory infiltrate consisting of neutrophils, lymphocytes, plasma cells, and histiocytes was present, with multiple foci of necrosis and abscess formation. All three cases demonstrated an identical immunophenotype: positive for CD68 and lysozyme; focally positive for S-100 protein, CD45RB, and CD4; and negative for CD3, CD20, CD21/CD35, CD1a, CD30, ALK1, myeloperoxidase, glial fibrillary acidic protein, and cytokeratin. The proliferative index ranged from 20% to 35%. Ultrastructural examination further confirmed the histiocytic nature of the tumor cells, characterized by irregularly folded or multisegmented nuclei and abundant cytoplasm containing lysosomes; Birbeck granules, interdigitating cell processes, and cell junctions were not found. Although the presence of abundant inflammatory cells could obscure the neoplastic histiocytes, making the distinction from inflammatory conditions difficult, awareness of this unusual histologic feature and the invariable finding of pleomorphic cells in some areas of the lesion permit the correct diagnosis to be made.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular dysplastic disorder, characterized by recurrent nosebleeds (epistaxis), multiple telangiectases and arteriovenous malformations (AVMs) in major organs. Mutations in Endoglin (ENG or CD105) and Activin receptor-like kinase 1 (ACVRL1 or ALK1) genes of the TGF-β superfamily receptors are responsible for HHT1 and HHT2 respectively and account for the majority of HHT cases. Haploinsufficiency in ENG and ALK1 is recognized at the underlying cause of HHT. However, the mechanisms responsible for the predisposition to and generation of AVMs, the hallmark of this disease, are poorly understood. Recent data suggest that dysregulated angiogenesis contributes to the pathogenesis of HHT and that the vascular endothelial growth factor, VEGF, may be implicated in this disease, by modulating the angiogenic-angiostatic balance in the affected tissues. Hence, anti-angiogenic therapies that target the abnormal vessels and restore the angiogenic-angiostatic balance are candidates for treatment of HHT. Here we review the experimental evidence for dysregulated angiogenesis in HHT, the anti-angiogenic therapeutic strategies used in animal models and some patients with HHT and the potential benefit of the anti-angiogenic treatment for ameliorating this severe, progressive vascular disease.

Bone morphogenetic protein (BMP)9 and BMP10 are high affinity ligands for activin receptor-like kinase 1 (ALK1), a type I BMP receptor mainly expressed on vascular endothelial cells (ECs). ALK1-mediated BMP9/BMP10 signalling pathways have emerged as essential in EC biology and in angiogenesis. Several genetic mutations in the genes encoding the ligands and receptors of this pathway have been reported in two cardiovascular diseases, pulmonary arterial hypertension (PAH) and hereditary haemorrhagic telangiectasia (HHT). Administration of recombinant BMP9 reverses experimental PAH in preclinical rodent models. Dalantercept, an Fc-fusion protein of the extracellular domain of ALK1 and a ligand trap for BMP9 and BMP10, is in phase II clinical trials for anti-tumour angiogenesis. Understanding the regulation of BMP9 and BMP10, at both gene and protein levels, under physiological and pathological conditions, will reveal essential information and potential novel prognostic markers for the BMP9/BMP10-targeted therapies.

A 48-year-old man of Haitian descent presented with progressive constipation, hematochezia, and weight loss. Colonoscopy and computed tomography scan revealed an obstructing colonic mass, causing intussusception and pneumatosis of the descending/upper sigmoid colon and necessitating an emergency left hemicolectomy. Gross examination revealed a 4.9-cm obstructing mass in the sigmoid colon extending through the muscularis propria. Histologically, the lesional cells were bland, spindled, with tapered and often wavy nuclei set in a loose fibromyxoid stroma. Focally, the lesional cells displayed whorling or storiform growth pattern mixed with spindle wavy cells. In many areas, the cells had bipolar cytoplasmic processes. Immunohistochemistry revealed patchy positivity for epithelial membrane antigen, CD34, vimentin, diffuse positivity for S-100, and negativity for CD117, cytokeratin (AE1/AE3), ALK1, desmin, smooth muscle actin, neuronal nuclei antigen (NeuN), and neurofilament protein. The morphology and immunohistochemical findings were consistent with hybrid perineurioma-schwannoma. Electron microscopic examination revealed the characteristic features of perineuriomal and schwannomatous differentiation. Based upon the histopathology, immunophenotype, and ultrastructure, this tumor was classified as a benign hybrid perineurioma-schwannoma, a counterpart to the tumor described in the soft tissue. This is the first case report of hybrid perineurioma-schwannoma in the colon.