Lorlatinib After Alectinib-Induced Pneumonitis: A Case Report

ALK gene rearrangements are detected in approximately 3% to 5% of NSCLC. ALK tyrosine kinase inhibitors, such as third-generation lorlatinib, have exhibited remarkable efficacy in ALK-rearranged NSCLC; however, they have been associated with a low incidence of treatment-limiting and potentially fatal drug-induced interstitial lung disease (ILD). There is concern that this may represent a class effect, a theory that is supported by a number of case reports. Because of clinical trial exclusion criteria, there are limited prospective data to guide decision-making after ALK tyrosine kinase inhibitors-induced ILD. A systematic review of the literature was conducted and only identified four reported cases of lorlatinib safety in this context. Here, we report the successful sequencing of lorlatinib in a patient who discontinued alectinib secondary to grade 3 drug-induced ILD.

How frail is frail in oncology studies? A scoping review

AIMS

The frailty index (FI) is one way in which frailty can be quantified. While it is measured as a continuous variable, various cut-off points have been used to categorise older adults as frail or non-frail, and these have largely been validated in the acute care or community settings for older adults without cancer. This review aimed to explore which FI categories have been applied to older adults with cancer and to determine why these categories were selected by study authors.

METHODS

This scoping review searched Medline, EMBASE, Cochrane, CINAHL, and Web of Science databases for studies which measured and categorised an FI in adults with cancer. Of the 1994 screened, 41 were eligible for inclusion. Data including oncological setting, FI categories, and the references or rationale for categorisation were extracted and analysed.

RESULTS

The FI score used to categorise participants as frail ranged from 0.06 to 0.35, with 0.35 being the most frequently used, followed by 0.25 and 0.20. The rationale for FI categories was provided in most studies but was not always relevant. Three of the included studies using an FI > 0.35 to define frailty were frequently referenced as the rationale for subsequent studies, however, the original rationale for this categorisation was unclear. Few studies sought to determine or validate optimum FI categorises in this population.

CONCLUSION

There is significant variability in how studies have categorised the FI in older adults with cancer. An FI ≥ 0.35 to categorise frailty was used most frequently, however an FI in this range has often represented at least moderate to severe frailty in other highly-cited studies. These findings contrast with a scoping review of highly-cited studies categorising FI in older adults without cancer, where an FI ≥ 0.25 was most common. Maintaining the FI as a continuous variable is likely to be beneficial until further validation studies determine optimum FI categories in this population. Differences in how the FI has been categorised, and indeed how older adults have been labelled as 'frail', limits our ability to synthesise results and to understand the impact of frailty in cancer care.

The impact of frailty on health outcomes in older adults with lung cancer: A systematic review

BACKGROUND

Frailty is prevalent in older adults with lung cancer, however the impact of frailty in this population is not well understood. The aim of this review was to evaluate the outcomes that are measured in frail older adults with lung cancer, and to determine the associations between frailty and these outcomes.

METHODS

A systematic online search of PubMed, EMBASE, and Cochrane databases was conducted to identify all English-language studies between January 2015 and May 2022 prospectively evaluating frailty and outcomes in older adults (median age > 65 years) with lung cancer. Studies were excluded if frailty was defined by a single domain assessment or not clearly defined. Quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Of 1891 studies screened, 16 met inclusion criteria. The median number of patients was 96 (range 26-494) and the mean age was 76.6 years. Eight different frailty assessments were used, and frailty definitions varied widely. The most frequently assessed outcomes were overall survival (n = 13,81%), treatment-related toxicity (n = 8,50%), hospitalisation (n = 5,31%), and treatment completion/discontinuation (n = 4,25%). Quality of life (n = 3,19%), function (n = 1,6%), frailty trajectory (n = 1,6%), and emergency visits (n = 1,6%) were infrequently assessed. Frailty had a strong and consistent association with mortality (Hazard Ratio range: 3.5-11.91). It was also associated with treatment-related toxicity and treatment selection. The remaining outcomes were not statistically significant.

CONCLUSION

These data support frailty as an important predictor of mortality in older adults with lung cancer, however further research is warranted to determine the association between frailty and other meaningful endpoints for this vulnerable population.

Hypolipidemia associated with inactivation of TM6SF2 is due to decreased VLDL-lipids secretion

Background

A missense variant in Transmembrane 6 Superfamily Member 2 [TM6SF2 (E167K)] is associated with reduced plasma lipid levels and protection from coronary atherosclerosis. The substitution of lysine for glutamate at residue 167 is associated with a marked decrease in TM6SF2 protein expression, consistent with a loss-of-function mutation. However the biological role of TM6SF2 is not known, and the mechanism(s) responsible for the hypolipidemia associated with mutation gene has not been fully defined. To elucidate the pathological mechanism for the hypolipidemia associated with TM6SF2 deficiency, we inactivated Tm6sf2 in mice and rats.

Methods

Tm6sf2−/− mice were generated as described previously. Two lines of Tm6sf2−/− rats with different frameshift mutations in exon 1 were generated using CRISPR/Cas9 technology. Primary hepatocytes were isolated from WT and Tm6sf2−/− mice for microscopy. Rats were fasted 16 or 4 hours and tissues were collected on ice for cell fractionation, and in liquid nitrogen for biochemical analyses. Frozen samples were stored at −80°C for subsequent analyses.

Result

In both mice and rats, inactivation of Tm6sf2 recapitulated the phenotype of humans with the E167K substitution: steatosis, reduced plasma lipid levels, and transaminitis. The phenotype was readily apparent in animals fed chow diets. Both species had reduced secretion of VLDL-TG, as determined by TRITON WR1399 injection, with no decrease in secretion of ApoB. Experiments in isolated perfused livers from WT and Tm6sf2−/− mice confirmed that the decreased TG secretion observed in intact animals reflected reduced TG secretion from the liver. Lipidomic analysis of the liver perfusates by by LC-MS indicated that secretion of cholesteryl esters, and phospholipids was also decreased in the KO animals. Taken together, these findings are consistent with a role for TM6SF2 in lipidation of ApoB-containing lipoproteins. To further elucidate the function of TM6SF2, we used fluorescence microscopy and cell fractionation to determine the subcellular localization of the protein. Microscopic analysis showed that TM6SF2 co-localized with ER and Golgi markers, but cell fractionation studies indicated that the protein is located primarily in the smooth ER. The ratio of TG to ApoB was lower in Golgi fractions from TM6sf2−/− rats than in corresponding fractions from WT animals.

Conclusions

Since the sequela of TM6SF2 inactivation are already apparent in the Golgi, we speculate that TM6SF2 promotes lipidation of VLDL in a pre-Golgi compartment. We are currently performing additional studies to further define the specific mechanism whereby TM6SF2 promotes lipidation of ApoB-containing lipoproteins.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): National Institutes of Health

Diagnosis and management of tropomyosin receptor kinase (TRK) fusion sarcomas: expert recommendations from the World Sarcoma Network

Sarcomas are a heterogeneous group of malignancies with mesenchymal lineage differentiation. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions as tissue-agnostic oncogenic drivers has led to new personalized therapies for a subset of patients with sarcoma in the form of tropomyosin receptor kinase (TRK) inhibitors. NTRK gene rearrangements and fusion transcripts can be detected with different molecular pathology techniques, while TRK protein expression can be demonstrated with immunohistochemistry. The rarity and diagnostic complexity of NTRK gene fusions raise a number of questions and challenges for clinicians. To address these challenges, the World Sarcoma Network convened two meetings of expert adult oncologists and pathologists and subsequently developed this article to provide practical guidance on the management of patients with sarcoma harboring NTRK gene fusions. We propose a diagnostic strategy that considers disease stage and histologic and molecular subtypes to facilitate routine testing for TRK expression and subsequent testing for NTRK gene fusions.

Oncogenic signaling by Kit tyrosine kinase occurs selectively on the Golgi apparatus in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are caused by gain-of-function mutations in the Kit receptor tyrosine kinase. Most primary GIST patients respond to the Kit inhibitor imatinib, but this drug often becomes ineffective because of secondary mutations in the Kit kinase domain. The characteristic intracellular accumulation of imatinib-sensitive and -resistant Kit protein is well documented, but its relationship to oncogenic signaling remains unknown. Here, we show that in cancer tissue from primary GIST patients as well as in cell lines, mutant Kit accumulates on the Golgi apparatus, whereas normal Kit localizes to the plasma membrane (PM). In imatinib-resistant GIST with a secondary Kit mutation, Kit localizes predominantly on the Golgi apparatus. Both imatinib-sensitive and imatinib-resistant Kit (Kit(mut)) become fully auto-phosphorylated only on the Golgi and only if in a complex-glycosylated form. Kit(mut) accumulates on the Golgi during the early secretory pathway, but not after endocytosis. The aberrant kinase activity of Kit(mut) prevents its export from the Golgi to the PM. Furthermore, Kit(mut) on the Golgi signals and activates the phosphatidylinositol 3-kinase–Akt (PI3K–Akt) pathway, signal transducer and activator of transcription 5 (STAT5), and the Mek–Erk pathway. Blocking the biosynthetic transport of Kit(mut) to the Golgi from the endoplasmic reticulum inhibits oncogenic signaling. PM localization of Kit(mut) is not required for its signaling. Activation of Src-family tyrosine kinases on the Golgi is essential for oncogenic Kit signaling. These results suggest that the Golgi apparatus serves as a platform for oncogenic Kit signaling. Our study demonstrates that Kit(mut)’s pathogenicity is related to its mis-localization, and may offer a new strategy for treating imatinib-resistant GISTs.

Long-term follow-up results of the multicenter phase II trial of regorafenib in patients with metastatic and/or unresectable GI stromal tumor after failure of standard tyrosine kinase inhibitor therapy

BACKGROUND

This investigator-initiated trial provided the justification for the phase III GRID study resulting in worldwide regulatory approval of regorafenib as a third-line therapy for patients with metastatic gastrointestinal stromal tumors (GIST). We report the genotype analyses, long-term safety, and activity results from this initial trial of regorafenib in GIST.

PATIENTS AND METHODS

The trial was conducted between February 2010 and January 2014, among adult patients with metastatic GIST, after failure of at least imatinib and sunitinib. Patients received regorafenib orally, 160 mg once daily, days 1-21 of a 28-day cycle. Clinical benefit rate (CBR), defined as complete or partial response (PR), or stable disease lasting ≥16 weeks per RECIST 1.1, progression-free survival (PFS), overall survival (OS), long-term safety data, and metabolic response by functional imaging were assessed.

RESULTS

Thirty-three patients received at least one dose of regorafenib. The median follow-up was 41 months. CBR was documented in 25 of 33 patients [76%; 95% confidence interval (CI) 58% to 89%], including six PRs. The median PFS was 13.2 months (95% CI 9.2-18.3 months) including four patients who remained progression-free at study closure, each achieving clinical benefit for more than 3 years (range 36.8-43.5 months). The median OS was 25 months (95% CI 13.2-39.1 months). Patients whose tumors harbored a KIT exon 11 mutation demonstrated the longest median PFS (13.4 months), whereas patients with KIT/PDGFRA wild-type, non-SDH-deficient tumors experienced a median 1.6 months PFS (P < 0.0001). Long-term safety profile is consistent with previous reports; hand-foot skin reaction and hypertension were the most common reasons for dose reduction. Notably, regorafenib induced objective responses and durable benefit in SDH-deficient GIST.

CONCLUSIONS

Long-term follow-up of patients with metastatic GIST treated with regorafenib suggests particular benefit among patients with primary KIT exon 11 mutations and those with SDH-deficient GIST. Dose modifications are frequently required to manage treatment-related toxicities.

CLINICAL TRIAL NUMBER

NCT01068769.

Multipoint targeting of the PI3K/mTOR pathway in mesothelioma

BACKGROUND

Mesothelioma is a notoriously chemotherapy-resistant neoplasm, as is evident in the dismal overall survival for patients with those of asbestos-associated disease. We previously demonstrated co-activation of multiple receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR), MET, and AXL in mesothelioma cell lines, suggesting that these kinases could serve as novel therapeutic targets. Although clinical trials have not shown activity for EGFR inhibitors in mesothelioma, concurrent inhibition of various activated RTKs has pro-apoptotic and anti-proliferative effects in mesothelioma cell lines. Thus, we hypothesised that a coordinated network of multi-RTK activation contributes to mesothelioma tumorigenesis.

METHODS

Activation of PI3K/AKT/mTOR, Raf/MAPK, and co-activation of RTKs were evaluated in mesotheliomas. Effects of RTK and downstream inhibitors/shRNAs were assessed by measuring mesothelioma cell viability/growth, apoptosis, activation of signalling intermediates, expression of cell-cycle checkpoints, and cell-cycle alterations.

RESULTS

We demonstrate activation of the PI3K/AKT/p70S6K and RAF/MEK/MAPK pathways in mesothelioma, but not in non-neoplastic mesothelial cells. The AKT activation, but not MAPK activation, was dependent on coordinated activation of RTKs EGFR, MET, and AXL. In addition, PI3K/AKT/mTOR pathway inhibition recapitulated the anti-proliferative effects of concurrent inhibition of EGFR, MET, and AXL. Dual targeting of PI3K/mTOR by BEZ235 or a combination of RAD001 and AKT knockdown had a greater effect on mesothelioma proliferation and viability than inhibition of individual activated RTKs or downstream signalling intermediates. Inhibition of PI3K/AKT was also associated with MDM2-p53 cell-cycle regulation.

CONCLUSIONS

These findings show that PI3K/AKT/mTOR is a crucial survival pathway downstream of multiple activated RTKs in mesothelioma, underscoring that PI3K/mTOR is a compelling target for therapeutic intervention.

Abundant Fas expression by gastrointestinal stromal tumours may serve as a therapeutic target for MegaFasL

Although the tyrosine kinase inhibitor imatinib has been shown to be an active agent in patients with gastrointestinal stromal tumours (GIST), complete remissions are almost never seen and most patients finally experience disease progression during their course of treatment. An alternative therapeutic option is to target death receptors such as Fas. We showed that a panel of imatinib-sensitive (GIST882) and imatinib-resistant (GIST48, GIST430 and GIST430K-) cell lines expressed Fas. MegaFasL, a recently developed hexameric form of soluble Fas ligand (FasL), appeared to be an active apoptosis-inducing agent in these cell lines. Moreover, MegaFasL potentiated the apoptotic effects of imatinib. Immunohistochemical evaluations, in 45 primary GISTs, underscored the relevance of the Fas pathway: Fas was expressed in all GISTs and was expressed strongly in 93%, whereas FasL was expressed at moderate and strong levels in 35 and 53% of GISTs, respectively. Fas and FasL expression were positively correlated in these primary GISTs, but there was no association between Fas or FasL expression and primary site, histological subtype, tumour size, mitotic index, risk classification, and KIT mutation status. The abundant immunohistochemical Fas and FasL expression were corroborated by western blot analysis. In conclusion, our data implicate Fas as a potential therapeutic target in GIST.

Heterogeneity of kinase inhibitor resistance mechanisms in GIST

Most GIST patients develop clinical resistance to KIT/PDGFRA tyrosine kinase inhibitors (TKI). However, it is unclear whether clinical resistance results from single or multiple molecular mechanisms in each patient. KIT and PDGFRA mutations were evaluated in 53 GIST metastases obtained from 14 patients who underwent surgical debulking after progression on imatinib or sunitinib. To interrogate possible resistance mechanisms across a broad biological spectrum of GISTs, inter- and intra-lesional heterogeneity of molecular drug-resistance mechanisms were evaluated in the following: conventional KIT (CD117)-positive GISTs with KIT mutations in exon 9, 11 or 13; KIT-negative GISTs; GISTs with unusual morphology; and KIT/PDGFRA wild-type GISTs. Genomic KIT and PDGFRA mutations were characterized systematically, using complementary techniques including D-HPLC for KIT exons 9, 11-18 and PDGFRA exons 12, 14, 18, and mutation-specific PCR (V654A, D820G, N822K, Y823D). Primary KIT oncogenic mutations were found in 11/14 patients (79%). Of these, 9/11 (83%), had secondary drug-resistant KIT mutations, including six (67%) with two to five different secondary mutations in separate metastases, and three (34%) with two secondary KIT mutations in the same metastasis. The secondary mutations clustered in the KIT ATP binding pocket and kinase catalytic regions. FISH analyses revealed KIT amplicons in 2/10 metastases lacking secondary KIT mutations. This study demonstrates extensive intra- and inter-lesional heterogeneity of resistance mutations and gene amplification in patients with clinically progressing GIST. KIT kinase resistance mutations were not found in KIT/PDGFRA wild-type GISTs or in KIT-mutant GISTs showing unusual morphology and/or loss of KIT expression by IHC, indicating that resistance mechanisms are fundamentally different in these tumours. Our observations underscore the heterogeneity of clinical TKI resistance, and highlight the therapeutic challenges involved in salvaging patients after clinical progression on TKI monotherapies.

Heterogeneity of kinase inhibitor resistance mechanisms in GIST

Most GIST patients develop clinical resistance to KIT/PDGFRA tyrosine kinase inhibitors (TKI). However, it is unclear whether clinical resistance results from single or multiple molecular mechanisms in each patient. KIT and PDGFRA mutations were evaluated in 53 GIST metastases obtained from 14 patients who underwent surgical debulking after progression on imatinib or sunitinib. To interrogate possible resistance mechanisms across a broad biological spectrum of GISTs, inter- and intra-lesional heterogeneity of molecular drug-resistance mechanisms were evaluated in the following: conventional KIT (CD117)-positive GISTs with KIT mutations in exon 9, 11 or 13; KIT-negative GISTs; GISTs with unusual morphology; and KIT/PDGFRA wild-type GISTs. Genomic KIT and PDGFRA mutations were characterized systematically, using complementary techniques including D-HPLC for KIT exons 9, 11-18 and PDGFRA exons 12, 14, 18, and mutation-specific PCR (V654A, D820G, N822K, Y823D). Primary KIT oncogenic mutations were found in 11/14 patients (79%). Of these, 9/11 (83%), had secondary drug-resistant KIT mutations, including six (67%) with two to five different secondary mutations in separate metastases, and three (34%) with two secondary KIT mutations in the same metastasis. The secondary mutations clustered in the KIT ATP binding pocket and kinase catalytic regions. FISH analyses revealed KIT amplicons in 2/10 metastases lacking secondary KIT mutations. This study demonstrates extensive intra- and inter-lesional heterogeneity of resistance mutations and gene amplification in patients with clinically progressing GIST. KIT kinase resistance mutations were not found in KIT/PDGFRA wild-type GISTs or in KIT-mutant GISTs showing unusual morphology and/or loss of KIT expression by IHC, indicating that resistance mechanisms are fundamentally different in these tumours. Our observations underscore the heterogeneity of clinical TKI resistance, and highlight the therapeutic challenges involved in salvaging patients after clinical progression on TKI monotherapies.

Protein kinase C-theta regulates KIT expression and proliferation in gastrointestinal stromal tumors

Oncogenic KIT or PDGFRA receptor tyrosine kinase mutations are compelling therapeutic targets in gastrointestinal stromal tumors (GISTs), and the KIT/PDGFRA kinase inhibitor, imatinib, is standard of care for patients with metastatic GIST. However, most of these patients eventually develop clinical resistance to imatinib and other KIT/PDGFRA kinase inhibitors and there is an urgent need to identify novel therapeutic strategies. We reported previously that protein kinase C-theta (PKCtheta) is activated in GIST, irrespective of KIT or PDGFRA mutational status, and is expressed at levels unprecedented in other mesenchymal tumors, therefore serving as a diagnostic marker of GIST. Herein, we characterize biological functions of PKCtheta in imatinib-sensitive and imatinib-resistant GISTs, showing that lentivirus-mediated PKCtheta knockdown is accompanied by inhibition of KIT expression in three KIT+/PKCtheta+ GIST cell lines, but not in a comparator KIT+/PKCtheta- Ewing's sarcoma cell line. PKCtheta knockdown in the KIT+ GISTs was associated with inhibition of the phosphatidylinositol-3-kinase/AKT signaling pathway, upregulation of the cyclin-dependent kinase inhibitors p21 and p27, antiproliferative effects due to G(1) arrest and induction of apoptosis, comparable to the effects seen after direct knockdown of KIT expression by KIT short-hairpin RNA. These novel findings highlight that PKCtheta warrants clinical evaluation as a potential therapeutic target in GISTs, including those cases containing mutations that confer resistance to KIT/PDGFRA kinase inhibitors.

KIT oncogenic signaling mechanisms in imatinib-resistant gastrointestinal stromal tumor: PI3-kinase/AKT is a crucial survival pathway

Most gastrointestinal stromal tumor (GIST) patients respond to KIT inhibition with imatinib, yet will eventually exhibit resistance. Imatinib-resistance mechanisms are heterogeneous, and little is known about KIT functional roles in imatinib-resistant GIST. Biological consequences of biochemical inhibition of KIT, phosphatidyl-inositol-3-kinase (PI3-K), PLCgamma, MAPK/ERK kinase/mitogen-activated protein kinase (MEK/MAPK), mammalian target of rapamycin (mTOR) and JAK were determined by immunoblotting for protein activation, and by cell proliferation and apoptosis assays in GIST cell lines from imatinib-sensitive GIST (GIST882), imatinib-resistant GISTs (GIST430 and GIST48) and KIT-negative GIST (GIST62). KIT activation was 3- to 6-fold higher in GIST430 and GIST48 than in GIST882, whereas total KIT expression was comparable in these three GIST lines. In addition to the higher set point for KIT activation, GIST430 and GIST48 had intrinsic imatinib resistance. After treatment with 1 muM imatinib, residual KIT activation was 6- and 2.8-fold higher in GIST430 and GIST48, respectively, compared to GIST882. In all GIST lines, cell growth arrest resulted from PI3-K inhibition, and - to a lesser extent - from MEK/MAPK and mTOR inhibition. Inhibition of JAK/STAT or PLCgamma did not affect cell proliferation. Similarly, only PI3-K inhibition resulted in substantial apoptosis in the imatinib-resistant GISTs. We conclude that GIST secondary KIT mutations can be associated with KIT hyperactivation and imatinib resistance. Targeting critical downstream signaling proteins, such as PI3-K, is a promising therapeutic strategy in imatinib-resistant GISTs.

KIT oncoprotein interactions in gastrointestinal stromal tumors: therapeutic relevance

Most gastrointestinal stromal tumors (GISTs) express oncogenic and constitutively active forms of the KIT or platelet-derived growth factor receptor alpha (PDGFRA) receptor tyrosine kinase proteins, and these kinase oncoproteins serve as targets for effective therapies. Given that mutant KIT oncoproteins serve crucial transforming roles in GISTs, we evaluated interactions with the KIT oncoproteins and determined signaling pathways that are dependent on KIT oncogenic activation in GISTs. Tyrosine-phosphorylated KIT oncoproteins interacted with PDGFRA, PDGFRB, phosphatidylinositol 3-kinase (PI3-K) and PKCtheta in GIST cells, and these interactions were abolished by KIT inhibition with imatinib or PKC412 or KIT RNAi. Notably, tyrosine-phosphorylated PDGFRA was prominent in frozen GIST tumors expressing KIT oncoproteins, suggesting that KIT-mediated PDGFRA phosphorylation is an efficient and biologically consequential mechanism in GISTs. Activated signaling intermediates were identified by immunoaffinity purification of tyrosine-phosphorylated proteins in GIST cells before and after treatment with KIT inhibitors, and these analyses show that GRB2, SHC, CBL and MAPK activation are largely KIT dependent in GISTs, whereas PI3-K, STAT1 and STAT3 activation are partially KIT dependent. In addition, we found that phosphorylation of several tyrosine kinase proteins - including JAK1 and EPHA4 - did not depend on KIT activation. Likewise, paxillin activation was independent of the KIT oncogenic signal. These studies identify signaling pathways that can provide both KIT-dependent and KIT-independent therapeutic synergies in GIST, and thereby highlight clinical strategies that might consolidate GIST therapeutic response to KIT/PDGFRA inhibition.

Insulin receptor activation in solitary fibrous tumours

Solitary fibrous tumours (SFTs) are known to overexpress insulin-like growth factor 2 (IGF-2). The down-stream oncogenic pathways of IGF-2, however, are not clear. Here we report uniform activation of the insulin receptor (IR) pathway in SFTs, which are mesenchymal tumours frequently associated with hypoglycaemia. Whereas the IR and its downstream signalling pathways were constitutively activated in SFTs, insulin-like growth factor 1 receptor (IGF-1R) was not expressed in these tumours. We also find that SFT cells secrete IGF-2 and proliferate in serum-free medium, consistent with an IGF-2/IR autocrine loop. The aetiological relevance of IGF-2 is supported by expression of IR-A, the IR isoform with high affinity for IGF-2, in all SFTs. Our studies suggest that IR activation plays an oncogenic role in SFTs.

Gastrointestinal stromal tumours overexpress fatty acid synthase

Fatty acid synthase (FASN), a key enzyme for de novo lipogenesis, is overexpressed in many malignant tumours and is associated with aggressive biological behaviour. FASN expression and its possible relationship with more aggressive behaviour in gastrointestinal stromal tumours (GISTs) have not been addressed to date. Here, FASN expression was assessed by immunohistochemistry in 60 primary GISTs (28 low/intermediate risk and 32 high risk) and seven metastatic GISTs. Sixteen smooth muscle gastrointestinal tumours were used as controls. FASN was overexpressed in 36 of 60 GISTs (60%): in 12 of 28 (42%) low/intermediate-risk GISTs and in 24 of 32 (75%) high-risk GISTs (p<0.05). Two primary and seven metastatic GISTs and five GIST cell lines (GIST882, GIST430, GIST522, GIST62, and GIST48), analysed by western blot, showed variable FASN expression. Most metastatic samples expressed high levels of FASN protein. Additionally, seven of 60 GISTs showed a proliferation rate higher than 10% by Ki67 and all of them expressed FASN (p<0.04). Finally, proliferation and apoptosis were investigated after FASN silencing in GIST882 cells, which displayed the highest FASN expression. siRNA-mediated FASN knock-down inhibited expression of the proliferation marker cyclin A, whereas no changes in p27 and cleaved PARP expression were seen. It is concluded that FASN is preferentially overexpressed in high-risk and metastatic GISTs, and that its overexpression likely contributes to cell proliferation.

KIT activation is a ubiquitous feature of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, and they are generally resistant to chemotherapy and radiation therapy. Most GISTs express the KIT receptor tyrosine kinase protein, and a subset of GISTs contain activating mutations within the KIT juxtamembrane region. We evaluated 48 GISTs, including 10 benign, 10 borderline, and 28 malignant cases, to determine whether KIT expression and activation are general properties of these tumors. Immunohistochemical KIT expression was demonstrated in each case. Somatic KIT mutations were found in 44 tumors (92%), of which 34 (71%) had juxtamembrane region mutations. Other GISTs had KIT mutations in the extracellular region (n = 6) and in two different regions in the tyrosine kinase domain (n = 4). Contrary to previous reports, KIT mutations were not identified preferentially in higher-grade tumors: indeed, they were found in each of 10 histologically benign GISTs. Notably, mutations in all KIT domains were associated with high-level KIT activation/phosphorylation, and KIT activation was also demonstrated in the four GISTs that lacked detectable KIT genomic and cDNA mutations. These studies underscore the role of KIT activation in GIST pathogenesis, and they suggest that activated KIT might represent a universal therapeutic target in GISTs.

Upper respiratory tract carcinoma with chromosomal translocation 15;19: evidence for a distinct disease entity of young patients with a rapidly fatal course

BACKGROUND

Carcinoma of the upper respiratory tract is rare in childhood, and cytogenetic aberrations have not been characterized in this population. The chromosomal translocation 15;19 has been reported four times previously. All patients were young and had tumors arising in the thorax. The three reports that provide clinical follow-up all describe superior vena cava syndrome and death soon after presentation. All tumors were diagnosed as carcinoma (three undifferentiated, one mucoepidermoid), and the authors suggested thymus, lung, or germ cell origin.

METHODS

The authors investigated the clinical and pathologic findings in two patients with poorly differentiated carcinoma showing evidence of t(15;19). This included a 13-year-old girl with a rapidly growing epiglottic mass, leading to superior vena cava syndrome and death and a 12-year-old girl with an aggressive nasopharyngeal mass showing intracranial extension.

RESULTS

The laryngeal tumor was poorly differentiated, with vesicular nuclei, prominent nucleoli, extensive necrosis, and a lymphoplasmacytic infiltrate; cells were positive for cytokeratin and negative for lymphoma, melanoma, germ cell, and endocrine markers. Electron microscopy showed rare intermediate junctions and basal lamina. The nasopharyngeal tumor was poorly differentiated with areas of obvious squamous differentiation observed histologically, immunophenotypically, and ultrastructurally. Cytogenetic and fluorescent in situ hybridization studies were consistent with t(15;19)(q13;p13.1) in both cases. Both children received chemo- and radiotherapy. The first child died of disease after 36 weeks; autopsy revealed tumor in the larynx with spread to the skin/subcutis (neck and thorax) and lymph nodes (cervical, subcarinal, and pulmonary hilar). The second child developed widespread bony metastases and died of disease after 13 weeks.

CONCLUSIONS

In conjunction with previous reports, the authors' findings show that t(15;19) is part of a distinct clinicopathologic entity characterized by young age, midline carcinoma of the neck or upper thorax, and a rapidly fatal course. Female gender and superior vena cava syndrome are common. The histogenesis of these distinctive tumors is unknown. The authors' findings suggest origin in the upper airway, perhaps from submucosal glands.

Gains of chromosome 8 are confined to mesenchymal components in pleuropulmonary blastoma

Pleuropulmonary blastoma, an aggressive tumor that is emerging as a distinct entity of childhood, is characterized by mesenchymal elements (including undifferentiated blastema and often cartilaginous, rhabdomyoblastic, or fibroblastic differentiation) and epithelium-lined spaces. We investigated two patients with pleuropulmonary blastoma, a 3-year-old boy and an 11-year-old girl, both with large cystic masses replacing one lung. In both children, the post-chemotherapy resection specimens showed more maturation of rhabdomyoblasts and more nuclear pleomorphism in all mesenchymal cell lines, compared with biopsies sampled before treatment. Karyotypic analysis demonstrated gains in chromosome 8 in both cases and 17p deletion in one case. Fluorescent in situ hybridization analysis demonstrated that the chromosome 8 gains were present in all mesenchymal elements, including undifferentiated blastematous, rhabdomyoblastic, fibroblastic, and chondroblastic areas. Epithelial cells showed no chromosome 8 gains. The chromosome 8 aberrations were not appreciably different in pre- versus post-chemotherapy tissue. Our findings substantiate previous reports that polysomy of chromosome 8 is a consistent feature of pleuropulmonary blastoma. Further, they indicate that clonal proliferation in pleuropulmonary blastoma is restricted to the malignant mesenchymal elements, supporting the notion that the epithelial components of this tumor are non-neoplastic.

Tumor formation and inactivation of RIZ1, an Rb-binding member of a nuclear protein-methyltransferase superfamily

The retinoblastoma protein-interacting zinc finger gene RIZ (PRDM2) is a member, by sequence homology, of a nuclear protein-methyltransferase (MTase) superfamily involved in chromatin-mediated gene expression. The gene produces two protein products, RIZ1 that contains a conserved MTase domain and RIZ2 that lacks the domain. RIZ1 gene expression is frequently silenced in human cancers, and the gene is also a common target of frameshift mutation in microsatellite-unstable cancers. We now report studies of mice with a targeted mutation in the RIZ1 locus. The mutation inactivates RIZ1 but not RIZ2. These RIZ1 mutant mice were viable and fertile but showed a high incidence of diffuse large B-cell lymphomas (DLBL) and a broad spectrum of unusual tumors. RIZ1 deficiency also accelerated tumorigenesis in p53 heterozygous mutant mice. Finally, several missense mutations of RIZ1 were found in human tumor tissues and cell lines; one of these was particularly common in human DLBL tumors. These missense mutations, as well as the previously described frameshift mutation, all mapped to the MTase functional domains. All abolished the capacity of RIZ1 to enhance estrogen receptor activation of transcription. These data suggest a direct link between tumor formation and the MTase domain of RIZ1 and describe for the first time a tumor susceptibility gene among methyltransferases.

STI571 inactivation of the gastrointestinal stromal tumor c-KIT oncoprotein: biological and clinical implications

Mutations in the c-KIT receptor occur somatically in many sporadic Gastrointestinal Stromal Tumors (GIST), and similar mutations have been identified at the germline level in kindreds with multiple GISTs. These mutations activate the tyrosine kinase activity of c-KIT and induce constitutive signaling. To investigate the function of activated c-KIT in GIST, we established a human GIST cell line, GIST882, which expresses an activating KIT mutation (K642E) in the first part of the cytoplasmic split tyrosine kinase domain. Notably, the K642E substitution is encoded by a homozygous exon 13 missense mutation, and, therefore, GIST882 cells do not express native KIT. GIST882 c-KIT protein is constitutively tyrosine phosphorylated, but tyrosine phosphorylation was rapidly and completely abolished after incubating the cells with the selective tyrosine kinase inhibitor STI571. Furthermore, GIST882 cells evidenced decreased proliferation and the onset of apoptotic cell death after prolonged incubation with STI571. Similar results were obtained after administering STI571 to a primary GIST cell culture that expressed a c-KIT exon 11 juxtamembrane mutation (K558NP). These cell-culture-based studies support an important role for c-KIT signaling in GIST and suggest therapeutic potential for STI571 in patients afflicted by this chemoresistant tumor.

Frequent fusion of the JAZF1 and JJAZ1 genes in endometrial stromal tumors

Endometrial stromal tumors are divided into three types: benign stromal nodules, endometrial stromal sarcomas, and undifferentiated endometrial sarcomas. A variety of cytogenetic abnormalities involving chromosome 7 have been reported in endometrial stromal sarcomas, including a recurrent t(7;17)(p15;q21). We have identified two zinc finger genes, which we have termed JAZF1 and JJAZ1, at the sites of the 7p15 and 17q21 breakpoints. Analyses of tumor RNA indicate that a JAZF1/JJAZ1 fusion is present in all types of endometrial stromal tumors; however, the fusion appears to be rarer among endometrial stromal sarcomas that would be considered high-grade according to certain classification schemes. These findings suggest that the less malignant endometrial stromal tumors may evolve toward more malignant types, but that some endometrial stromal sarcomas with relatively abundant mitotic activity may compose a biologically distinct group.

Signal transduction pathways in sarcoma as targets for therapeutic intervention

Investigations into the molecular alterations in sarcomas have made substantial progress during the past decade. Classical linkage analysis and the direct sequencing of chromosomal translocation fusions have identified candidate genes in many different sarcomas. A large group of these genes participate in signal transduction pathways and represent potential sites of disease intervention with targeted therapies. This review will discuss five types of sarcoma that display aberrant tyrosine kinase pathway signaling: gastrointestinal stromal tumor, inflammatory myofibroblastic tumor, congenital fibrosarcoma and mesoblastic nephroma, dermatofibrosarcoma protuberans, and desmoplastic small round cell tumor; one sarcoma predisposition syndrome with specific dysregulation of the ras pathway--neurofibromatosis--will also be discussed.

BAL is a novel risk-related gene in diffuse large B-cell lymphomas that enhances cellular migration

Clinical risk factor models such as the International Prognostic Index are used to identify diffuse large B-cell lymphoma (DLB-CL) patients with different risks of death from their diseases. To elucidate the molecular bases for these observed clinical differences in outcome, differential display was used to identify a novel gene, termed BAL (B-aggressive lymphoma), which is expressed at significantly higher levels in fatal high-risk DLB-CLs than in cured low-risk tumors. The major BAL complementary DNA encodes a previously uncharacterized 88-kd nuclear protein with a duplicated N-terminal domain homologous to the nonhistone portion of histone-macroH2A and a C-terminal alpha-helical region with 2 short coiled-coil domains. Of note, the BAL N-terminus and secondary structure resemble those of a recently identified human protein, KIAA1268. In addition, both BAL and KIAA1268 map to chromosome 3q21, further suggesting that these genes belong to a newly identified family. BAL is expressed at increased levels in DLB-CL cell lines with an activated peripheral B cell, rather than a germinal center B cell, phenotype. This observation and the characteristic dissemination of high risk DLB-CLs prompted studies regarding the role of BAL in B-cell migration. In classical transwell assays, stable BAL-overexpressing B-cell lymphoma transfectants had significantly higher rates of migration than vector-only transfectants, indicating that the risk-related BAL gene promotes malignant B-cell migration. (Blood. 2000;96:4328-4334)

Isochromosome 7q in adult Wilms' tumors: diagnostic and pathogenetic implications

Wilms' tumors affecting adults are rare and are thought to have a worse prognosis than similar stage tumors in the pediatric population. To understand these tumors better, the authors reviewed their multi-institutional experience in a series of nine lesions diagnosed as Wilms' tumors in adults. In addition to histologic and immunohistochemical examination, they performed cytogenetic analysis and fluorescence in situ hybridization. On review, four cases were reclassified: two "blastema only" as Ewing's sarcoma/primitive neuroectodermal tumor and the other two as clear cell sarcoma of soft parts and sarcoma not otherwise specified (NOS). Of the remaining five cases, three exhibited biphasic histology and two were triphasic. In this group, there were three women and two men, and patient age ranged from 17 to 37 years (median age, 26 years). Tumor size was large and ranged from 10 to 31 cm (median tumor size, 12.5 cm). Histologically, the tumors showed the typical features of Wilms' tumors with varying amounts of blastema (n = 5), epithelium (n = 5), and stroma (n = 2). No tumors contained anaplasia, and persistent renal blastema was not identified in the non-neoplastic kidney in any specimen. All tumors were positive for cytokeratins (CK7, n = 3; pankeratin, n = 5), and one tumor was weakly positive for CD99 (0-13). Molecular analysis including dual color fluorescence in situ hybridization (all tumors), and cytogenetic analysis (n = 2) disclosed the presence of isochromosome 7q in three of five tumors whereas all tumors were diploid with respect to chromosome 12. Follow-up data ranged from 6 to 133 months (median follow-up, 82 months) with progression in only one patient who had stage IV disease with lymph node and lung metastases at presentation. The authors conclude that adult Wilms' tumor has been overdiagnosed. Most "blastema-only" tumors in adults are not Wilms' tumors, and in an adult, biphasic morphology should be the minimum criteria for their diagnosis. Using strict diagnostic criteria, adult Wilms' tumors have a relatively favorable prognosis. The characteristic findings of isochromosome 7q, lack of trisomy or tetrasomy for chromosome 12, and absence of persistent renal blastema suggest that the pathogenesis of Wilms' tumors in adults may be different than in the pediatric population. These genetic features may be helpful in distinguishing adult Wilms' tumors from other primary renal tumors.

NPAT links cyclin E-Cdk2 to the regulation of replication-dependent histone gene transcription

In eukaryotic cells, histone gene expression is one of the major events that mark entry into S phase. While this process is tightly linked to cell cycle position, how it is regulated by the cell cycle machinery is not known. Here we show that NPAT, a substrate of the cyclin E-Cdk2 complex, is associated with human replication-dependent histone gene clusters on both chromosomes 1 and 6 in S phase. We demonstrate that NPAT activates histone gene transcription and that this activation is dependent on the promoter elements (SSCSs) previously proposed to mediate cell cycle-dependent transcription. Cyclin E is also associated with the histone gene loci, and cyclin E-Cdk2 stimulates the NPAT-mediated activation of histone gene transcription. Thus, our results both show that NPAT is involved in a key S phase event and provide a link between the cell cycle machinery and activation of histone gene transcription.

PLAG1 fusion oncogenes in lipoblastoma

Lipoblastomas are pediatric neoplasms resulting from transformation of adipocytes. These benign tumors are typically composed of adipose cells in different stages of maturation within a variably myxoid matrix, and they contain clonal rearrangements of chromosome band 8q12. Because lipoblastomas resemble embryonic adipose tissue, characterization of their transforming mechanisms might reveal biological pathways in physiological adipogenesis. Herein, we demonstrate that lipoblastoma chromosome 8q12 rearrangements bring about promoter-swapping events in the PLAG1 oncqgene. We show that the hyaluronic acid synthase 2 (HAS2) or collagen 1 alpha 2 (COL1A2) gene promoter regions are fused to the entire PLAG1 coding sequence in each of four lipoblastomas. PLAG1 is a developmentally regulated zinc finger gene whose tumorigenic function has been shown previously only in epithelial salivary gland cells. Our findings reveal that PLAG1 activation, presumably resulting from transcriptional up-regulation, is a central oncogenic event in lipoblastoma.

PAX8-PPARgamma1 fusion oncogene in human thyroid carcinoma [corrected]

Chromosomal translocations that encode fusion oncoproteins have been observed consistently in leukemias/lymphomas and sarcomas but not in carcinomas, the most common human cancers. Here, we report that t(2;3)(q13;p25), a translocation identified in a subset of human thyroid follicular carcinomas, results in fusion of the DNA binding domains of the thyroid transcription factor PAX8 to domains A to F of the peroxisome proliferator-activated receptor (PPAR) gamma1. PAX8-PPARgamma1 mRNA and protein were detected in 5 of 8 thyroid follicular carcinomas but not in 20 follicular adenomas, 10 papillary carcinomas, or 10 multinodular hyperplasias. PAX8-PPARgamma1 inhibited thiazolidinedione-induced transactivation by PPARgamma1 in a dominant negative manner. The experiments demonstrate an oncogenic role for PPARgamma and suggest that PAX8-PPARgamma1 may be useful in the diagnosis and treatment of thyroid carcinoma.

ZNF198-FGFR1 transforming activity depends on a novel proline-rich ZNF198 oligomerization domain

An acquired chromosomal translocation, t(8;13)(p11;q11-12), observed in a distinctive type of stem cell leukemia/lymphoma syndrome, leads to the fusion of the 5' portion of ZNF198 and the 3' portion of FGFR1. ZNF198-FGFR1 fusion transcripts encode 4 to 10 zinc fingers, a proline-rich region, and the intracellular portion of the FGFR1 (fibroblast growth factor receptor 1) receptor tyrosine kinase. We demonstrate that the ZNF198 proline-rich region constitutes a novel self-association domain. When fused to the intracellular domain of FGFR1, the ZNF198 proline-rich region is sufficient to cause oligomerization, FGFR1 tyrosine kinase activation, and transformation of Ba/F3 cells to IL-3 independent growth. (Blood. 2000;96:699-704)

A t(2;19)(p13;p13.2) in a giant invasive cardiac lipoma from a patient with multiple lipomatosis

Cardiac lipomas occur infrequently but account for a significant portion of rare cardiac tumors. Common cutaneous lipomas have previously been associated with rearrangements of chromosome band 12q15, which often disrupt the high-mobility-group protein gene HMGIC. In this report, we describe the cytogenetic analysis of an unusual giant cardiac lipoma that exhibited myocardial invasion in a patient with a history of multiple lipomatosis (cutaneous lipoma, lipomatous gynecomastia, lipomatous hypertrophy of the interatrial septum, and dyslipidemia). Cytogenetic studies of cells derived from the cardiac lipoma demonstrated no abnormalities of chromosome 12, but did reveal a t(2;19)(p13;p13.2). A liposarcoma-derived oncogene (p115-RhoGEF) previously mapped to chromosome 19 and the low-density lipoprotein receptor gene (LDLR) previously mapped to chromosome band 19p13 were evaluated to determine whether they were disrupted by this translocation. Fluorescence in situ hybridization analyses assigned p115-RhoGEF to chromosome 19 in bands q13.2-q13.3 and mapped the LDLR to chromosome arm 19p in segment 13.2, but centromeric to the t(2;19) breakpoint. Thus, these genes are unlikely to be involved in the t(2;19)(p13;p13.2). Further studies of the regions of chromosomes 2 and 19 perturbed by the translocation in this unusual infiltrating cardiac lipoma will identify gene(s) that participate in adipocyte growth and differentiation and may provide insight into syndromes of multiple lipomatosis.

KIT extracellular and kinase domain mutations in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms arising in the gastrointestinal tract. GISTs express the KIT receptor tyrosine kinase, and many cases have activating mutations in the KIT juxtamembrane region. We now report an analysis of KIT cDNA and genomic sequences in eight GISTs that lack juxtamembrane region mutations. Six cases contained heterozygous exon 9 mutations in which six nucleotides, encoding Ala-Tyr, were duplicated. The other two cases contained homozygous exon 13 missense mutations, resulting in substitution of Glu for Lys(642), that were associated with constitutive KIT tyrosine phosphorylation. Sequence analysis of DNAs from nonneoplastic companion tissues revealed that both the exon 9 and exon 13 mutations were somatic. These are the first descriptions, in any tumor, of mutations in KIT exons encoding the C-terminal end of the extracellular domain and the first part of the split kinase domain. These findings indicate that KIT may be activated by mutations in at least three domains-extracellular, juxtamembrane, and kinase-in GISTs.

A human pituitary tumor-derived folliculostellate cell line

Pituitary cells have been used for the study of hormone synthesis, secretion, and regulation. However, the lack of human cell lines of pituitary origin has made such studies in humans very difficult. Activin, a member of the transforming growth factor-beta cytokine family, is secreted by the pituitary and serves, in addition to regulating hormone biosynthesis, as a regulator of cell growth and differentiation. In the human pituitary, folliculo-stellate cells secrete an activin-binding and -neutralizing protein, follistatin. However, the role of these cells in the autocrine/paracrine regulatory mechanisms of activin is poorly understood. We describe a human pituitary-derived folliculostellate cell line, designated PDFS, that was developed spontaneously from a clinically nonfunctioning pituitary macroadenoma. PDFS cells showed an epithelial-like morphology with long cytoplasmic processes. Electron microscopy revealed frequent intercellular junctions, including desmosomes, and cytogenetic analysis showed clonal characteristics with chromosomal abnormalities. These cells express vimentin and the nervous tissue-specific S-100 protein, specific markers of folliculostellate cells in the anterior pituitary, but no secretory pituitary cell markers. PDFS cells formed large colonies in an anchorage-independent transformation assay. They express follistatin and activin A and have an intact activin intracellular signaling pathway as determined by reporter assays. Therefore, this human cell line provides a useful model for studying the regulation of cell growth and cytokine production by factors endogenously produced in pituitary folliculostellate cells.

Breakpoints of the t(11;18)(q21;q21) in mucosa-associated lymphoid tissue (MALT) lymphoma lie within or near the previously undescribed gene MALT1 in chromosome 18

Lymphomas arising in mucosa-associated lymphoid tissue (MALT) are indolent B-cell tumors that have a predilection for epithelial sites and often develop in a setting of chronic inflammation or autoimmunity. As many as 50% of low-grade MALT lymphomas contain an (11;18)(q21; q21) chromosomal translocation. Using fluorescence in situ hybridization, we have analyzed the position of recombination within chromosome 18 DNA in three examples of MALT lymphoma bearing this translocation. In all three cases, the breakpoint maps to DNA in BAC b357H2, covering about 150 kb of sequence. A previously undescribed, ubiquitously expressed gene, which we refer to as MALT1, was identified within this sequence and was found to be broken in one case for which we have definitively located the position of recombination between chromosomes 18 and 11. The sequence of this gene indicates the presence of two immunoglobulin-like C2 domains and a region of partial homology to caspases, suggesting a possible role for MALT1 in the regulation of apoptosis.

DNA in situ hybridization as an adjunct in tumor diagnosis

DNA in situ hybridization (ISH) methods, particularly fluorescence in situ hybridization, have gained broad acceptance in the clinical cytogenetic and research communities, but are used less frequently by noncytogenetic diagnostic pathology services. This review discusses tumor-related ISH, including the advantages and limitations of enzymatic detection ("insituhistochemistry"). The ISH applications are categorized with respect to diagnostic capabilities, ease of use, and cost.

Renal cell carcinomas in children and young adults: increased incidence of papillary architecture and unique subtypes

Renal cell carcinomas in children and young adults are rare, and the pathologic features of these tumors have not been well described. We reviewed 24 renal cell carcinomas in children and young adults ages 6 to 29 years, 14 of whom were younger than 18 years of age. Fourteen were female. In 19 (79%) of 24 cases, the tumor met histologic criteria for papillary renal cell carcinoma, with at least 50% papillary architecture. Four of the remaining five cases were typical clear cell tumors in patients known to have von Hippel Lindau syndrome, and one case was of chromophobe type. In the papillary tumors, calcifications, high nuclear grade, extracapsular extension (American Joint Commission on Cancer stage T3), and lymph node metastases were common. Among these papillary tumors, four distinct histologic patterns could be identified. Collecting duct-like tumors (two cases) involved the large collecting ducts, were multifocal and predominantly papillary, and had focal tubular and solid areas. These tumors were reactive for epithelial membrane antigen (EMA) and keratins, including CK7, but negative for Ulex europeaus and high molecular weight keratin 34BE12. Voluminous cell tumors (four cases) were composed of cells with extremely voluminous clear cytoplasm and, although predominantly papillary, had areas that also resembled clear cell tumors. These tumors were reactive for keratins AE1/AE3 but were otherwise negative for all other keratins, EMA, and U. europeaus. One of these tumors showed an X;7 translocation. Adult type tumors (12 cases) resembled papillary tumors of adults. These tumors were reactive for EMA and keratins, including CK7, and all but one were negative for U. europeaus and keratin 34BE12. This last case had trisomies of chromosomes 7, 16, 17, and 20. The final neuroendocrinelike case was multifocal, organoid, and composed of nests of small cells in a neuroendocrinelike pattern. Three of 13 patients were alive with disease at last follow-up, and three additional patients died of disease, all within 2 years. Progression was highly associated with lymph node involvement at the time of resection. We conclude that the clinicopathologic features of renal cell carcinomas in children and young adults differ from those arising in older adults. These tumors are characteristically high-grade, high-stage, papillary tumors with numerous calcifications, and several subtypes can be identified based on histologic, immunohistochemical, and cytogenetic features. Some subtypes appear to be unique to this age group.

Skeletal and extraskeletal myxoid chondrosarcoma: related or distinct tumors?

Skeletal myxoid chondrosarcoma is a histologic variant of conventional skeletal myxoid chondrosarcoma, whereas extraskeletal myxoid chondrosarcoma is a distinct entity characterized by a reciprocal t(9;22) translocation resulting in fusion of the EWS and CHN genes. Rarely, extraskeletal myxoid chondrosarcoma can occur in bone, and it is difficult to describe such tumors, unambiguously, using the present nomenclature. Designation as "chordoid sarcoma of bone" would distinguish these cases from conventional skeletal myxoid chondrosarcoma.

HER-2/neu (c-erb-B2) gene and protein in breast cancer

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. The association of HER-2/neu gene and protein abnormalities with prognosis in breast cancer is presented by considering a series of 52 published studies including more than 16,000 patients. The relative advantages and disadvantages of Southern blot testing, polymerase chain reaction amplification, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed with immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The importance of HER-2/neu protein overexpression in ductal carcinoma in situ, and HER-2/neu protein status in uncommon breast diseases in female patients and breast cancer in male patients are also considered. The potential value of HER-2/neu protein status for the prediction of response to therapy in breast cancer is presented for standard hormonal therapy, cytotoxic chemotherapy, and radiation therapy. Also evaluated is the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response. Finally, preliminary data concerning use of antibody-based therapies directed against HER-2/neu protein and their potential use in breast cancer treatment are considered.

Clear cell sarcoma of soft parts: report of a case primary in the kidney with cytogenetic confirmation

Clear cell sarcoma of soft parts (CCSSP), also known as malignant melanoma of soft parts, is an aggressive tumor that usually presents in soft tissue and very rarely in small bowel. We report a case arising in the kidney of a 20-year-old man which was difficult to distinguish from Wilms' tumor. The tumor metastasized to the liver and lungs, and the patient died of disseminated disease 5 years after his initial presentation. Both the primary and metastatic tumors were composed predominantly of spindle cells with occasional more epithelioid areas that were inconsistently arranged in nests. In both primary and metastatic sites, the tumor surrounded and entrapped normal epithelial elements, mimicking the biphasic appearance of Wilms' tumor. The tumor cells, however, were positive for S-100 protein and HMB45 and negative for keratin and CD99, and cytogenetic analysis revealed a clonal abnormality, translocation t(12;22)(q13;q12), characteristic of CCSSP. This result was verified by fluorescence in situ hybridization on paraffin-embedded tissue, which demonstrated EWS gene-region rearrangement. CCSSP joins a growing list of tumors that typically arise in soft tissue (PNET, solitary fibrous tumor, and infantile/congenital fibrosarcoma), but can also present in the kidney and may be confused with primary renal tumors. Awareness of this possibility and the use of ancillary studies. including immunohistochemistry, cytogenetic analysis, and fluorescence in situ hybridization, are important for accurate diagnosis.

Investigation of chromosomal aberrations in hepatocellular carcinoma by fluorescence in situ hybridization

Molecular cytogenetic approaches have been applied only rarely in the characterization of hepatocellular carcinoma (HCC). The aim in this study was to evaluate aberrations, particularly deletions, of specific chromosomal regions in HCC. Dual-color fluorescence in situ hybridization (FISH) was performed on intact nuclei from touch preparations of 17 HCCs and 1 hepatic adenoma. Each touch preparation was hybridized with a digoxigenin-labeled centromere probe and a biotin-labeled unique sequence probe from the same chromosome. This approach permitted the simultaneous evaluation of ploidy changes and chromosome arm deletions. Eight noncentromeric chromosome regions, 3p14, 4q21, 6q14, 6q21, 8p12, 8p22, 9p21, and 9p24 were selected for study on the basis of their having been implicated as tumor suppressor regions in HCC or other common types of carcinoma. Together with the 5 corresponding centromeric probes on chromosomes 3, 4, 6, 8, and 9, a total of 13 chromosome loci were evaluated. All cases of hepatocellular carcinoma showed at least one deletion or aneuploidy. The hepatic adenoma was all diploid. Chromosome 4q21 showed the highest rate of deletion (76.5%) and aneusomy (88%). The second and the third were chromosome 8p22 and 6q14, which showed 59% and 47% of deletion, respectively. A 4q21 deletion is also the most frequent single chromosome aberration. Prominent tumor heterogeneity and variable deletion patterns were noted. Interphase FISH was an efficient means for evaluating numerical and structural chromosome aberrations in HCCs. Most HCCs contained deletions of known tumor suppressor regions (4q and 8p), and a novel deletion hotspot was demonstrated on chromosome band 6q14.

Classification of human liposarcoma and lipoma using ex vivo proton NMR spectroscopy

Prognostication in patients with liposarcoma is a complex and controversial subject based on recognition of lipoblasts, adipocyte nuclear atypia, and qualitative estimations of cellularity and cell size. We show here that for 30 patients with liposarcoma and 5 patients with lipoma, spectral differences on high-resolution, magic angle spinning proton nuclear magnetic resonance (hr-MAS 1H-NMR) spectroscopy relate to known biochemical changes and correlate with adipocyte tissue differentiation, histologic cell type, and cellularity. The NMR-visible level of triglyceride is shown to correlate with liposarcoma differentiation, since the triglyceride level in well-differentiated liposarcoma is 33-fold higher on average than for myxoid/round cell liposarcoma, which in turn is 6-fold higher than the dedifferentiated and/or pleomorphic subtypes. The NMR-visible phosphatidylcholine level serves as an estimate of total tissue cell membrane phospholipid mass and was found to correlate with liposarcoma subtype. Pleomorphic liposarcoma, the most aggressive and metastatic subtype, was found to have a threefold increase in NMR-visible phosphatidylcholine level compared with dedifferentiated liposarcoma. The level of NMR-visible phosphatidylcholine was twofold greater in well-differentiated liposarcoma compared with lipoma and was threefold larger for the hypercellular myxoid/round cell subtype compared with the pure myxoid histology. Thus, NMR-derived parameters of tissue lipid may be used for objective distinction of liposarcoma histologic subtype/grade and lipoma from liposarcoma. These biochemical parameters may ultimately improve prognostication in patients with liposarcoma.

The HER-2/neu oncogene: prognostic factor, predictive factor and target for therapy

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. HER-2/neu has been widely studied in breast cancer. The potential value of HER-2/neu status for the prediction of disease outcome and response to therapy in breast cancer is presented in the light of a series of recently published studies showing a range of impact on the outcome of patients treated with hormonal, cytotoxic and radiation therapies. This review includes the application of serum-based HER-2/neu testing and the use of antibody-based therapies directed against the HER-2/neu protein and their potential to become a new modality for breast cancer treatment.

Classification of human liposarcoma and lipoma using ex vivo proton NMR spectroscopy

Prognostication in patients with liposarcoma is a complex and controversial subject based on recognition of lipoblasts, adipocyte nuclear atypia, and qualitative estimations of cellularity and cell size. We show here that for 30 patients with liposarcoma and 5 patients with lipoma, spectral differences on high-resolution, magic angle spinning proton nuclear magnetic resonance (hr-MAS 1H-NMR) spectroscopy relate to known biochemical changes and correlate with adipocyte tissue differentiation, histologic cell type, and cellularity. The NMR-visible level of triglyceride is shown to correlate with liposarcoma differentiation, since the triglyceride level in well-differentiated liposarcoma is 33-fold higher on average than for myxoid/round cell liposarcoma, which in turn is 6-fold higher than the dedifferentiated and/or pleomorphic subtypes. The NMR-visible phosphatidylcholine level serves as an estimate of total tissue cell membrane phospholipid mass and was found to correlate with liposarcoma subtype. Pleomorphic liposarcoma, the most aggressive and metastatic subtype, was found to have a threefold increase in NMR-visible phosphatidylcholine level compared with dedifferentiated liposarcoma. The level of NMR-visible phosphatidylcholine was twofold greater in well-differentiated liposarcoma compared with lipoma and was threefold larger for the hypercellular myxoid/round cell subtype compared with the pure myxoid histology. Thus, NMR-derived parameters of tissue lipid may be used for objective distinction of liposarcoma histologic subtype/grade and lipoma from liposarcoma. These biochemical parameters may ultimately improve prognostication in patients with liposarcoma.

The HER-2/neu oncogene in breast cancer: prognostic factor, predictive factor, and target for therapy

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. HER-2/neu has been widely studied in breast cancer. In this review, the association of HER-2/neu gene and protein abnormalities studied by Southern and slot blotting, immunohistochemistry, enzyme immunoassays, and fluorescence in situ hybridization with prognosis in breast cancer is studied in depth by review of a series of 47 published studies encompassing more than 15,000 patients. The relative advantages of gene amplification assays and frozen/fresh tissue immunohistochemistry over paraffin section immunohistochemistry are discussed. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The potential value of HER-2/neu status for the prediction of response to therapy in breast cancer is presented in the light of a series of recently published studies showing a range of impact on the outcome of patients treated with hormonal, cytotoxic, and radiation therapies. The evidence that HER-2/neu gene and protein abnormalities in breast cancer predict resistance to tamoxifen therapy and relative sensitivity to chemotherapy regimens including adriamycin is presented. The review will also evaluate the status of serum-based testing for circulating the HER-2/neu receptor protein and its ability to predict disease outcome and therapy response. In the final section, the review will briefly present preliminary data concerning the use of antibody-based therapies directed against the HER-2/neu protein and their potential to become a new modality for breast cancer treatment. The recently presented phase III clinical trial evidence that systemic administration of anti-HER2 antibodies (Herceptin), alone and in combination with cytotoxic chemotherapy in patients with HER-2/neu overexpressing primary tumors, can increase the time to recurrence and overall response rates in metastatic breast cancer is reviewed.

The pericentromeric inversion, inv (6)(p25q13), is a novel diagnostic marker in chondromyxoid fibroma

Chondromyxoid fibroma is a benign bone tumor that arises most commonly in the metaphysis of long bones in young adults. The cytogenetic features of this tumor are not well known. In this study, four chondromyxoid fibromas were karyotyped after short-term cell culture. All of the tumors contained clonal rearrangements of chromosome 6, and each of these rearrangements involved band 6q13. Two tumors contained a pericentromeric inversion, inv (6)(p25q13), which was described recently in chondromyxoid fibroma. 6q13 rearrangements are not associated with other types of bone and soft tissue tumors, and the inv (6)(p25q13) is reported only in chondromyxoid fibroma. Hence, this cytogenetic marker might be helpful in distinguishing chondromyxoid fibroma from chondrosarcoma and other histologic mimics. The consistent occurrence of 6q13 rearrangements suggests a specific oncogenic mechanism in chondromyxoid fibroma, most likely involving oncogene activation.

Congenital mesoblastic nephroma t(12;15) is associated with ETV6-NTRK3 gene fusion: cytogenetic and molecular relationship to congenital (infantile) fibrosarcoma

Morphological, cytogenetic, and biological evidence supports a relationship between congenital (infantile) fibrosarcoma (CFS) and congenital mesoblastic nephroma (CMN). These tumors have a very similar histological appearance, and they are both associated with polysomies for chromosomes 8, 11, 17, and 20. Recently, CFS was shown to contain a novel t(12; 15)(p13;q25) translocation resulting in ETV6-NTRK3 gene fusion. The aims of this study were to determine whether congenital mesoblastic nephroma contains the t(12;15)(p13;q25) translocation and ETV6-NTRK3 gene fusion and whether ETV6-NTRK3 fusions, in CMN and CFS, antedate acquisition of nonrandom chromosome polysomies. To address these aims, we evaluated 1) ETV6-NTRK3 fusion transcripts by reverse transcriptase polymerase chain reaction and sequence analysis, 2) genomic ETV6-region chromosomal rearrangement by fluorescence in situ hybridization, and 3) chromosomal polysomies by karyotyping and fluorescence in situ hybridization. We report ETV6-NTRK3 fusion transcripts and/or ETV6-region rearrangement in five of six CMNs and in five of five CFSs. The ETV6-NTRK3 fusion transcripts and/or ETV-region chromosome rearrangements were demonstrated in two CMNs and one CFS that lacked chromosome polysomies. These findings demonstrate that t(12;15) translocation, and the associated ETV6-NTRK3 fusion, can antedate acquisition of chromosome polysomies in CMN and CFS. CMN and CFS are pathogenetically related, and it is likely that they represent a single neoplastic entity, arising in either renal or soft tissue locations.