A review of pediatric macromastia etiology and indications for reduction mammaplasty

BACKGROUND

Macromastia in adolescents is both physically and psychologically debilitating during a period in life when individuals are particularly vulnerable to peer pressure and social norms. Early recognition and intervention by both pediatricians and surgeons are critical to avoid unnecessary suffering. While reduction mammaplasty is the gold standard for the management of symptomatic macromastia in adults, the management of macromastia in pediatric patients remains controversial. In particular, there is great discussion regarding the timing of reconstructive breast surgery in pediatric patients.

METHODS

A comprehensive review of the literature was performed to identify all articles related to macromastia in patients ≤16 years of age, the age at which full development is typically achieved in the United States. The etiologies of pediatric macromastia, approaches to management, and outcomes are summarized herein.

FINDINGS

Pathological breast hypertrophy in pediatric patients is a rare finding and may occur secondary to juvenile hypertrophy of the breast (JHB) and pseudoangiomatous stromal hyperplasia (PASH). While medical management of these pathologies has been attempted with varying success, reduction mammaplasty is safe and effective in pediatric patients. There are, however, a number of pediatric-specific considerations that must be taken into account prior to surgery. We provide an algorithm for approaching pediatric macromastia.

Eomes function is conserved between zebrafish and mouse and controls left-right organiser progenitor gene expression via interlocking feedforward loops

The T-box family transcription factor Eomesodermin (Eomes) is present in all vertebrates, with many key roles in the developing mammalian embryo and immune system. Homozygous Eomes mutant mouse embryos exhibit early lethality due to defects in both the embryonic mesendoderm and the extraembryonic trophoblast cell lineage. In contrast, zebrafish lacking the predominant Eomes homologue A (Eomesa) do not suffer complete lethality and can be maintained. This suggests fundamental differences in either the molecular function of Eomes orthologues or the molecular configuration of processes in which they participate. To explore these hypotheses we initially analysed the expression of distinct Eomes isoforms in various mouse cell types. Next we compared the functional capabilities of these murine isoforms to zebrafish Eomesa. These experiments provided no evidence for functional divergence. Next we examined the functions of zebrafish Eomesa and other T-box family members expressed in early development, as well as its paralogue Eomesb. Though Eomes is a member of the Tbr1 subfamily we found evidence for functional redundancy with the Tbx6 subfamily member Tbx16, known to be absent from eutherians. However, Tbx16 does not appear to synergise with Eomesa cofactors Mixl1 and Gata5. Finally, we analysed the ability of Eomesa and other T-box factors to induce zebrafish left-right organiser progenitors (known as dorsal forerunner cells) known to be positively regulated by vgll4l, a gene we had previously shown to be repressed by Eomesa. Here we demonstrate that Eomesa indirectly upregulates vgll4l expression via interlocking feedforward loops, suggesting a role in establishment of left-right asymmetry. Conversely, other T-box factors could not similarly induce left-right organiser progenitors. Overall these findings demonstrate conservation of Eomes molecular function and participation in similar processes, but differential requirements across evolution due to additional co-expressed T-box factors in teleosts, albeit with markedly different molecular capabilities. Our analyses also provide insights into the role of Eomesa in left-right organiser formation in zebrafish.

3 '-5 ' crosstalk contributes to transcriptional bursting

BACKGROUND

Transcription in mammalian cells is a complex stochastic process involving shuttling of polymerase between genes and phase-separated liquid condensates. It occurs in bursts, which results in vastly different numbers of an mRNA species in isogenic cell populations. Several factors contributing to transcriptional bursting have been identified, usually classified as intrinsic, in other words local to single genes, or extrinsic, relating to the macroscopic state of the cell. However, some possible contributors have not been explored yet. Here, we focus on processes at the 3 ' and 5 ' ends of a gene that enable reinitiation of transcription upon termination.

RESULTS

Using Bayesian methodology, we measure the transcriptional bursting in inducible transgenes, showing that perturbation of polymerase shuttling typically reduces burst size, increases burst frequency, and thus limits transcriptional noise. Analysis based on paired-end tag sequencing (PolII ChIA-PET) suggests that this effect is genome wide. The observed noise patterns are also reproduced by a generative model that captures major characteristics of the polymerase flux between the ends of a gene and a phase-separated compartment.

CONCLUSIONS

Interactions between the 3 ' and 5 ' ends of a gene, which facilitate polymerase recycling, are major contributors to transcriptional noise.

Nicotinamide Nucleotide Transhydrogenase as a Novel Treatment Target in Adrenocortical Carcinoma

Adrenocortical carcinoma (ACC) is an aggressive malignancy with poor response to chemotherapy. In this study, we evaluated a potential new treatment target for ACC, focusing on the mitochondrial reduced form of NAD phosphate (NADPH) generator nicotinamide nucleotide transhydrogenase (NNT). NNT has a central role within mitochondrial antioxidant pathways, protecting cells from oxidative stress. Inactivating human NNT mutations result in congenital adrenal insufficiency. We hypothesized that NNT silencing in ACC cells will induce toxic levels of oxidative stress. To explore this, we transiently knocked down NNT in NCI-H295R ACC cells. As predicted, this manipulation increased intracellular levels of oxidative stress; this resulted in a pronounced suppression of cell proliferation and higher apoptotic rates, as well as sensitization of cells to chemically induced oxidative stress. Steroidogenesis was paradoxically stimulated by NNT loss, as demonstrated by mass spectrometry-based steroid profiling. Next, we generated a stable NNT knockdown model in the same cell line to investigate the longer lasting effects of NNT silencing. After long-term culture, cells adapted metabolically to chronic NNT knockdown, restoring their redox balance and resilience to oxidative stress, although their proliferation remained suppressed. This was associated with higher rates of oxygen consumption. The molecular pathways underpinning these responses were explored in detail by RNA sequencing and nontargeted metabolome analysis, revealing major alterations in nucleotide synthesis, protein folding, and polyamine metabolism. This study provides preclinical evidence of the therapeutic merit of antioxidant targeting in ACC as well as illuminating the long-term adaptive response of cells to oxidative stress.

Identification of metastatic papillary thyroid carcinoma in FNA specimens using thyroid peroxidase immunohistochemistry

INTRODUCTION

We evaluated immunohistochemical staining for thyroid peroxidase (TPO), a glycoprotein found in the apical plasma membrane of thyroid follicular cells, as a marker for metastatic PTC in FNA samples and compared results with thyroglobulin (Tg) and thyroid transcription factor 1 (TTF1) staining.

METHODS

Cell block sections prepared from 100 FNA specimens were stained with a rabbit monoclonal antibody to TPO (EP159). The FNAs included 64 metastatic malignancies from non-thyroid primary sites, including 18 lung, and 36 cases of thyroid tumours (29 PTC, six cases of medullary thyroid carcinoma and one thyroid anaplastic carcinoma). Thyroid tumours were stained with TTF1 and Tg in addition to TPO. All cases of metastatic lung carcinoma also had TTF-1 staining results.

RESULTS

TPO staining was negative in all non-thyroid malignancies. Ninety percent (26/29) of PTC were positive. All positive cases showed strong cytoplasmic staining, although 54% (14/26) showed positivity in less than half of the cells. By comparison, Tg staining of TPC cases was present in 62% and TTF-1 in 100%. In addition to showing higher sensitivity, interpretation of staining results with TPO was generally easier with than Tg. All metastatic lung adenocarcinomas were positive for TTF-1 and TPO negative. The six medullary cancers showed positivity in 17%, 0% and 83% with TPO, Tg and TTF-1, respectively.

CONCLUSIONS

TPO (mAb EP159) may be a useful addition to immunohistochemical panels for FNA specimens where metastatic PTC is a consideration, particularly in cases where metastatic lung carcinoma features in the differential diagnosis.

Modeling Enzyme Processivity Reveals that RNA-Seq Libraries Are Biased in Characteristic and Correctable Ways

Experimental procedures for preparing RNA-seq and single-cell (sc) RNA-seq libraries are based on assumptions regarding their underlying enzymatic reactions. Here, we show that the fairness of these assumptions varies within libraries: coverage by sequencing reads along and between transcripts exhibits characteristic, protocol-dependent biases. To understand the mechanistic basis of this bias, we present an integrated modeling framework that infers the relationship between enzyme reactions during library preparation and the characteristic coverage patterns observed for different protocols. Analysis of new and existing (sc)RNA-seq data from six different library preparation protocols reveals that polymerase processivity is the mechanistic origin of coverage biases. We apply our framework to demonstrate that lowering incubation temperature increases processivity, yield, and (sc)RNA-seq sensitivity in all protocols. We also provide correction factors based on our model for increasing accuracy of transcript quantification in existing samples prepared at standard temperatures. In total, our findings improve our ability to accurately reflect in vivo transcript abundances in (sc)RNA-seq libraries.

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Characterization of global RNA-seq biases specific to library preparation protocols

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Mathematical framework to reverse engineer enzyme reactions that cause bias

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Insights from reverse engineering allow optimization of RNA-seq protocols

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Lowered incubation temperatures during library preparation improve sensitivity

Meta-analysis of inter-patient pharmacokinetic variability of liposomal and non-liposomal anticancer agents

A meta-analysis was conducted to evaluate the inter-patient pharmacokinetic (PK) variability of liposomal and small molecule (SM) anticancer agents. Inter-patient PK variability of 9 liposomal and SM formulations of the same drug was evaluated. PK variability was measured as coefficient of variance (CV%) of area under the plasma concentration versus time curve (AUC) and the fold-difference between AUCmax and AUCmin (AUC range). CV% of AUC and AUC ranges were 2.7-fold (P<0.001) and 16.7-fold (P=0.13) greater, respectively, for liposomal compared with SM drugs. There was an inverse linear relationship between the clearance (CL) of liposomal agents and PK variability with a lower CL associated with greater PK variability (R(2)=0.39). PK variability of liposomal agents was greater when evaluated from 0-336 h compared with 0-24h. PK variability of liposomes is significantly greater than SM. The factors associated with the PK variability of liposomal agents need to be evaluated.

FROM THE CLINICAL EDITOR

In this meta-analysis, the inter-patient pharmacokinetic variability of 9 liposomal and small molecule anti-cancer agents was studied. The authors determined that several parameters are in favor of the liposomal formulation; however, the PK variability of the formulation was higher compared with small molecule agents, the reason for which remains to be determined in future studies.

[Orbital invasion of a maxillary ameloblastoma]

A 66-year-old man with a history of repeated surgery, external radiation and brachytherapy for ameloblastoma presented with a recurrence of the tumor with sinus, intraorbital and skull base infiltration. Histopathologic examination of the resected orbital and sinus tissue confirmed the diagnosis of ameloblastoma. Immunohistochemical staining for CD56 was strongly positive in the tumor cells. Although ameloblastoma is usually a low-grade malignant tumor, it can be locally aggressive with invasion of the surrounding tissue. Maxillary ameloblastomas are more likely to infiltrate the orbit.

The role of intrathoracic free flaps for chronic empyema

BACKGROUND

The management of chronic empyema associated with a bronchopleural fistula can be a particularly challenging problem. Successful eradication may not occur without interposition of healthy vascularized tissue. Pedicled muscle flaps for coverage on the thorax have been well described. However, secondary to trauma or previous surgical procedures, a pedicle flap may not be sufficiently sized or available. Free tissue transfer is an attractive option to provide the appropriate vascularized tissue.

METHODS

Six patients with chronic empyema-bronchopleural fistulae were reconstructed with 4 rectus abdominis myocutaneous and 2 gracilis muscle flaps. The choice of recipient vessels was dictated by existing local anatomy but included intercostal, thoracodorsal, thoracoacromial, azygous, and circumflex humeral vessels. One flap required interposition saphenous vein grafts for both artery and vein.

RESULTS

Patient follow-up ranged from 2 to 14 years. There were no episodes of flap loss or postoperative mortality. Empyema resolution without recurrent bronchopleural fistula was achieved in all patients.

CONCLUSIONS

Free tissue transfer is an excellent option for vascularized tissue interposition in patients who are not candidates for pedicled muscle transfer. Multiple potential recipient vessels provide tremendous versatility, arguing for early consideration of free tissue transfer.

Abstract 371: Comparison of toxicity and study design issues of nanoparticle and small molecule anticancer agents in preclinical models and phase I clinical trials

Background: Carrier-mediated agents (CMA) are classified as nanoparticles, nanosomes (nanoparticle sized liposomes) and conjugates. Anticancer CMA offer many unique advantages over their traditional small molecule (SM) counterparts, including improved solubility, longer duration of exposure, tumor-selective delivery, increased antitumor response and reduced toxicity. The interpatient variability in pharmacokinetics (PK) and pharmacodynamics (PD) associated with nanoparticles are greater than that observed with SM. The starting dose for phase I studies of SM and CMA anticancer agents is based on the toxicity profile of the most sensitive species (e.g. rat or canine). However, the optimal animal model for toxicologic and pharmacologic studies of CMA is unclear. Our preliminary data suggests that dogs are highly sensitive to nanoparticles and thus may not be an appropriate animal model in determining the starting dose of CMA for phase I clinical trials. We evaluated preclinical toxicology data and how this affected the design and progression of phase I studies of CMA compared to SM anticancer agents.

Methods: In preclinical studies, the maximum tolerated dose (MTD) in rats and dogs was evaluated for CMA and their respective SM. In phase I clinical trials of CMA and their respective SM in patients with advanced solid tumors, the basis for starting dose, the number of dose escalations, number of patients and the ratio of MTD to starting dose was determined.

Results: Starting dose in phase I studies of CMA was based on dogs.

Abstract 1295: Relationship between pharmacokinetic (PK) sampling schema and reported PK variability of liposomes in patients

Introduction: Liposomal formulations offer advantages over small molecules including increased solubility, selective targeting potential and prolonged drug exposure. Compared with conventional formulations, these agents often have greater PK and pharmacodynamic variability, which is attributed to the role of the mononuclear phagocyte system in the clearance of liposomes. Inter-patient variability in drug exposure, represented by area under the curve (AUC), of encapsulated drug can be 20- to 100-fold. However, some nanoparticle and liposomal agents report lower inter-patient PK variability. Study design and sampling schema may affect the documentation of PK variability, due to the prolonged systemic exposure of encapsulated drug. Thus, we evaluated the reported PK variability of PEGylated CKD-602 (S-CKD602) and non-liposomal CKD-602 (NL-CKD-602) using a short (0-24 h) and long (0-336 h) sampling schema.

Methods: S-CKD602 and NL-CKD-602 were administered at doses ranging from 0.5 to 2.1 mg/m2 in phase I studies of patients with advanced solid tumors. Blood samples were obtained from baseline to 336 h for S-CKD602 and from baseline to 24 h for NL-CKD-602. Plasma concentration of total (lactone + hydroxy acid) encapsulated CKD-602 from S-CKD602 and total CKD-602 from NL-CKD-602 were measured by LC-MS/MS. AUC from 0 to 24 h (AUC0-24) and 0 to 336 h (AUC0-336) were calculated. The coefficient of variance % (CV%) in AUC0-24 and AUC0-336 at each dose level were calculated for S-CKD602 and NL-CKD-602. Results:

Abstract 3696: Pharmacokinetics (PK) of XMT-1001, a novel polymeric prodrug of camptothecin, in mice bearing HT-29 human colon carcinoma xenografts

Introduction: XMT-1001 is a water soluble macromolecular conjugate of camptothecin (CPT). In this novel CPT prodrug, CPT is conjugated with a ∼60 kDa biodegradable hydrophilic polyacetal, poly (1-hydroxymethylethylene hydroxymethylformal) (PHF). Dual-phase release of CPT from XMT-1001 occurs via lipophilic intermediates, CPT-20-O-(N-succinimido-glycinate) (CPT-SI) and CPT-20-O-(N-succinamidoyl-glycinate) (CPT-SA). Hydrolysis of intermediates results in formation of an active-lactone form of CPT. XMT-1001 is designed to produce a prolonged exposure in plasma and tumor and to improve CPT's therapeutic index. We evaluated plasma, tumor and tissue PK of XMT-1001, CPT-SI, CPT-SA and CPT in mice bearing HT-29 human colon cancer xenografts.

Methods: XMT-1001 was administered at 60 mg CPT equivalents/kg IV x 1 via a tail vein. Mice (n = 3) were sacrificed at 0.083 to 24, 48, 72, 168 and 336 h after administration. Plasma, tumor and tissue samples were processed to measure the total (lactone + hydroxy acid) forms of XMT-1001, CPT-SI, CPT-SA and CPT via LC-MS/MS. Area under concentration versus time curves (AUC0-t) and time of last detectable concentration (TLast) were calculated.

Results: PlasmaTumorLiver AUC0-t (ng/mL·h)TLast (h)AUC0-t (ng/mL·h)TLast (h)AUC0-t (ng/mL·h)TLast (h)XMT-10013,639,034168138,156336663,493336CPT-SI53,653248,85033613,239336CPT-SA46,010241,59516814,063336CPT8,86024853481,11616

Conclusions: CPT conjugation to the polymer carrier, PHF, provides a water soluble formulation with potential advantages of extended systemic exposure to the conjugated drug XMT-1001, conjugated release products CPT-SI and CPT-SA, and active drug CPT. After XMT-1001 administration, the majority of plasma exposure is accounted for by conjugated CPT. The analysis of XMT-1001 revealed substantial tumor and tissue accumulation and extended exposure of conjugated drug and conjugated release products CPT-SI, CPT-SA and CPT. The improved tumor distribution and extended localized release of small molecule prodrugs and active CPT by XMT-1001 are hypothesized to improve safety and efficacy over existing drugs of the same class.

Supported by Mersana Therapeutics.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3696.

Reduced alpha-defensin expression is associated with inflammation and not NOD2 mutation status in ileal Crohn's disease

BACKGROUND AND AIMS

Reduced ileal Paneth cell alpha-defensin expression has been reported to be associated with Crohn's disease, especially in patients carrying NOD2 mutations. The aim of this study was to independently assess whether NOD2, alpha-defensins and Crohn's disease are linked.

METHODS

Using quantitative real-time polymerase chain reaction (RT-PCR), we measured the mRNA expression levels of key Paneth cell antimicrobial peptides (DEFA5, DEFA6, LYZ, PLA2G2A), inflammatory cytokines [interkelukin 6 (IL6) and IL8], and a marker of epithelial cell content, villin (VIL1) in 106 samples from both affected ileum (inflamed Crohn's disease cases, n = 44) and unaffected ileum (non-inflamed; Crohn's disease cases, n = 51 and controls, n = 11). Anti-human defensin 5 (HD-5) and haematoxylin/eosin immunohistochemical staining was performed on parallel sections from NOD2 wild-type and NOD2 mutant ileal Crohn's disease tissue.

RESULTS

In Crohn's disease patients, DEFA5 and DEFA6 mRNA expression levels were 1.9- and 2.2-fold lower, respectively, in histologically confirmed inflamed ileal mucosa after adjustment for confounders (DEFA5, p<0.001; DEFA6, p = 0.001). In contrast to previous studies, we found no significant association between alpha-defensin expression and NOD2 genotype. HD-5 protein data supports these RNA findings. The reduction in HD-5 protein expression appears due to surface epithelial cell loss and reduced Paneth cell numbers as a consequence of tissue damage.

CONCLUSIONS

Reduction in alpha-defensin expression is independent of NOD2 status and is due to loss of surface epithelium as a consequence of inflammatory changes rather than being the inciting event prior to inflammation in ileal Crohn's disease.

Exportin 1 inhibition attenuates nuclear factor-kappaB-dependent gene expression

Activation of nuclear factor (NF)-kappaB is mediated by signal-induced phosphorylation of IkappaBalpha, subsequent IkappaBalpha degradation, and then translocation of unbound NF-kappaB to the nucleus. Termination of gene expression occurs when IkappaBalpha binds NF-kappaB subunits (Rel A) in the nucleus. Leptomycin B specifically inhibits export of IkappaBalpha and the inactive IkappaBalpha/Rel A complex via the nuclear export protein exportin 1. We hypothesized that inhibition of IkappaBalpha nuclear export would increase nuclear IkappaBalpha and attenuate NF-kappaB inflammatory gene expression in pulmonary microvascular endothelial cells. We found that inhibition of exportin 1 causes nuclear accumulation of both endogenous NF-kappaB (Rel A) and IkappaBalpha. IL-1beta causes nuclear accumulation of NF-kappaB (Rel A) but does not increase nuclear IkappaBalpha. Inhibition of exportin 1 before IL-1beta prevented an increase in the nuclear ratio of NF-kappaB (Rel A) to IkappaBalpha and decreases NF-kappaB DNA binding. Furthermore, inhibition of exportin 1 attenuates IL-1beta-induced phosphorylation of IkappaBalpha without affecting IkappaB kinase phosphorylation. Lastly, inhibition of exportin 1 attenuates monocyte chemoattractant protein, IL-8, and intercellular adhesion molecule expression in response to IL-1beta stimulation. We suggest that the decrease in cell activation due to exportin 1 inhibition is a result of termination of NF-kappaB DNA binding due to increased concentration of IkappaBalpha in the nucleus.

A frame-shift mutation of PMS2 is a widespread cause of Lynch syndrome

BACKGROUND

When compared to the other mismatch repair genes involved in Lynch syndrome, the identification of mutations within PMS2 has been limited (<2% of all identified mutations), yet the immunohistochemical analysis of tumour samples indicates that approximately 5% of Lynch syndrome cases are caused by PMS2. This disparity is primarily due to complications in the study of this gene caused by interference from pseudogene sequences.

METHODS

Using a recently developed method for detecting PMS2 specific mutations, we have screened 99 patients who are likely candidates for PMS2 mutations based on immunohistochemical analysis.

RESULTS

We have identified a frequently occurring frame-shift mutation (c.736_741del6ins11) in 12 ostensibly unrelated Lynch syndrome patients (20% of patients we have identified with a deleterious mutation in PMS2, n = 61). These individuals all display the rare allele (population frequency <0.05) at a single nucleotide polymorphism (SNP) in exon 11, and have been shown to possess a short common haplotype, allowing us to calculate that the mutation arose around 1625 years ago (65 generations; 95% confidence interval 22 to 120).

CONCLUSION

Ancestral analysis indicates that this mutation is enriched in individuals with British and Swedish ancestry. We estimate that there are >10 000 carriers of this mutation in the USA alone. The identification of both the mutation and the common haplotype in one Swedish control sample (n = 225), along with evidence that Lynch syndrome associated cancers are rarer than expected in the probands' families, would suggest that this is a prevalent mutation with reduced penetrance.

Characterization of tumour-infiltrating lymphocytes and apoptosis in colitis-associated neoplasia: comparison with sporadic colorectal cancer

The development of colorectal cancer is a major complication for patients with chronic idiopathic colitis. Colitis-associated tumours tend to occur at a younger age and be more aggressive than sporadic colorectal cancers. While we have previously associated the presence of tumour-infiltrating lymphocytes (TILs) and increased apoptosis in sporadic colorectal cancer with high-level microsatellite instability and improved prognosis, little is known of the relationship between these variables in colitis-associated colorectal cancer. The aim of this study was to correlate TILs and tumour cell apoptosis in colitis-associated neoplasms stratified according to microsatellite instability. Twenty tumour and 11 dysplastic samples resected from 21 patients with long-standing colitis were analysed for microsatellite instability at 10 microsatellite markers. TIL distribution (CD3, CD8) and function (granzyme B) were quantified by immunohistochemistry. Neoplastic cell apoptosis was assessed using the M30 CytoDEATH antibody. These findings were compared with 40 microsatellite stable (MSS) sporadic colorectal cancers previously evaluated for TILs and neoplastic apoptosis. Low-level microsatellite instability was found in 1/20 colitis-associated tumours. All other colitis-associated lesions were designated MSS. CD3(+) and CD8(+) TIL counts were significantly higher in colitis-associated lesions compared with MSS sporadic colorectal cancer (p < 0.0001, p = 0.001 respectively). Despite their higher TIL density, colitis-associated tumours were more likely to present late (Dukes' stage C or D) (p = 0.02). Functionally, colitis-associated TILs demonstrated significantly less granzyme B expression compared to sporadic cancers (p = 0.002). The level of tumour cell apoptosis was similar between the two groups (sporadic, 1.53%; colitis cancers, 1.45%). In conclusion, MSS colitis-associated tumours have a higher prevalence of CD3(+)/CD8(+) TILs but no associated increase in tumour cell killing by apoptosis. Unlike cytotoxic T cells in sporadic colorectal cancer, TILs do not appear to enhance the prognosis of colitis-associated colorectal cancer. This may be related to an impairment of granzyme B expression within these lesions.

Melanoma inhibits macrophage activation by suppressing toll-like receptor 4 signaling

BACKGROUND

Activated macrophages defend against tumors by secreting cytokines to recruit secondary immune cells, presenting antigen to T cells, and by direct tumor cytotoxicity. Peritoneal macrophages harvested from melanoma-bearing mice are less cytotoxic to melanoma cells, and produce less superoxide, nitric oxide, and tumor necrosis factor-alpha (TNF-alpha) than those from nontumor-bearing mice. Similar impairment of macrophage activation occurs in vitro using media harvested from cultured melanoma cells. Stimulation of Toll-like receptor 4 (TLR-4) activates macrophages and results in the release of TNF-alpha. We hypothesized that melanoma inhibits macrophage activation by suppressing TLR-4 signaling.

STUDY DESIGN

Melanoma conditioned media (MCM) was generated from B16 melanoma cells. Peritoneal macrophages from TLR-4 competent or TLR-4 incompetent mice were exposed to control or MCM for 24 hours; then stimulated with lipopolysaccharide. TNF-alpha secretion, TNF-alpha mRNA production, nuclear factor-kappaB (NF-kappaB) activation, and TLR-4 surface expression were measured.

RESULTS

Peritoneal macrophages exposed to MCM produced considerably less TNF-alpha in response to stimulus than controls (691 pg/mL versus 2,066 pg/mL, p < 0.001). TNF-alpha production by TLR-4 incompetent macrophages was not affected by MCM (454 pg/mL versus 480 pg/mL). Stimulated TNF-alpha mRNA and activated NF-kappaB were decreased in MCM treated C57BL/6 macrophages (by 38% and 33%, respectively). TLR-4 surface expression, however, was not decreased by exposure to MCM.

CONCLUSIONS

Melanoma inhibits macrophage activation by suppressing TLR-4 signaling downstream of the TLR-4 receptor.

Major mesh-related complications following hernia repair

Mesh material affects complications following hernia repair. Medical device reports on the use of surgical mesh for hernia repair were reviewed from the Food and Drug Administration's (FDA) Manufacturer User Facility Device Experience Database from January 1996 to September 2004. We analyzed 252 adverse event reports related to the use of surgical mesh for hernia repair. Adverse events included infection (42%, 107 reports), mechanical failure (18%, 46), pain (9%, 23), reaction (8%, 20), intestinal complications (7%, 18), adhesions (6%, 14), seroma (4%, 9), erosion (2%, 6), and other (4%, 9). Compared to all other mesh types, Sepra/polypropylene mesh had more mechanical failures (80 vs 14%, p < 0.05), biomaterial mesh had more reactions (57 vs 7%, p < 0.05), polytetrafluoroethylene (PTFE)/polypropylene mesh had more intestinal complications (14 vs 7%, p < 0.05), and PTFE mesh tended to have more infections (75 vs 41% all other, p = 0.07). Death occurred in 2% (5). We conclude that specific mesh materials are related to specific complications.

Polymerized Hemoglobin Induces Heme Oxygenase-1 Protein Expression and Inhibits Intercellular Adhesion Molecule-1 Protein Expression in Human Lung Microvascular Endothelial Cells

BACKGROUND

Our clinical trials using a polymerized hemoglobin solution (PolyHb) as a red cell substitute in severely injured patients suggested that this hemoglobin-based oxygen carrier has a systemic antiinflammatory effect. Heme oxygenase-1 (HO-1) has recently been shown to be cytoprotective, and is known to be induced by heme moieties. We investigated the effects of this hemoglobin-based oxygen carrier on HO-1 induction and proinflammatory activation of pulmonary endothelium.

STUDY DESIGN

Human lung microvascular endothelial cells were grown to confluence and preincubated with either cell media (control) or with an equal volume mixture of polymerized hemoglobin/cell media (experimental). The cell cultures were subsequently stimulated with lipopolysaccharide. HO-1 expression was detected by protein immunoblot and further quantified by ELISA; intercellular adhesion molecule-1 protein expression was measured by flow cytometry.

RESULTS

Polymerized hemoglobin induced synthesis of HO-1 protein in human lung microvascular endothelial cells and, concurrently, inhibited lipopolysaccharide-induced intercellular adhesion molecule-1 protein cell surface expression.

CONCLUSIONS

Polymerized hemoglobin attenuates lipopolysaccharide-stimulated expression of intercellular adhesion molecule-1 protein, which is associated with upregulation of the cytoprotective protein HO-1 in human pulmonary endothelial cells. This antiinflammatory effect offers a novel mechanism by which hemoglobin-based oxygen carrier solutions may be exploited therapeutically as resuscitative fluids.

Promoter hypermethylation frequency and BRAF mutations distinguish hereditary non-polyposis colon cancer from sporadic MSI-H colon cancer

BACKGROUND

Colorectal cancers resulting from defective DNA mismatch repair can occur in both hereditary non-polyposis colon cancer (HNPCC) and in the sporadic setting. They are characterised by a high level of microsatellite instability (MSI-H) and superficially resemble each other in that they are frequently located in the proximal colon and share features such as circumscribed tumour margins and tumour-infiltrating lymphocytes. However, significant differences can be demonstrated at the molecular level including widespread promoter hypermethylation and BRAF -activating mutations which occur significantly less often in HNPCC.

AIMS

In this study, we sought to determine whether the presence of widespread promoter hypermethylation and BRAF mutations would exclude HNPCC.

MATERIALS AND METHODS

We investigated the methylation status of four methylated in tumour markers (MINTs 1,2,12 and 31), and the promoter regions of 5 genes hMLH1, HPP1, MGMT, p16INK4A and p14ARF, in 21 sporadic MSI-H colorectal cancers and compared these with 18 cancers from HNPCC patients. The methylation status of CpG islands were determined by either methylation specific PCR (MSP) or combined bisulfite restricton analysis (COBRA). In addition we considered the BRAF mutation status of 18 HNPCC tumours and 19 sporadic MSI-H cancers which had been previously determined by RFLP analysis and confirmatory sequencing.

RESULTS

Methylation of the promoter regions in target genes occurred less frequently within the HNPCC tumours (27% of analyses), compared with the sporadic MSI-H tumours (59% of analyses) (P < 0.001). Methylation of MINTs 1, 2, 12 and 31 occurred in 4% of analyses for HNPCC tumours contrasted with 73% for sporadic MSI-H tumours (P < 0.001). BRAF mutations were detected in 74% of sporadic tumours but none of the HNPCC cancers tested.

CONCLUSIONS

The total number of genes and MINTs methylated in HNPCC was lower than in MSI-H colorectal tumours. No HNPCC tumour showed evidence of widespread promoter hypermethylation or BRAF mutation suggesting this feature could be used as a discriminator between familial and sporadic cases.

BRAF mutation is associated with DNA methylation in serrated polyps and cancers of the colorectum

BACKGROUND AND AIMS

Mutations in BRAF have been linked with colorectal cancers (CRC) showing high level microsatellite instability (MSI-H). However, the distribution of BRAF mutations in MSI-H cancers remains to be clarified with respect to precursor lesions and the CpG island methylator phenotype (CIMP).

METHODS

Forty three hyperplastic polyps (HP), nine mixed polyps (MP), five serrated adenomas (SA), 28 conventional adenomas (AD), 18 hereditary non-polyposis colorectal cancers (HNPCC), and 127 sporadic CRC (46 MSI-H and 81 non-MSI-H) were collected from patients undergoing colectomy for either CRC or hyperplastic polyposis. Twenty five of 57 serrated lesions were derived from four patients with hyperplastic polyposis. HP were further subdivided according to recently documented morphological criteria into 27 classical HP and 16 variant lesions described as "sessile serrated adenoma" (SSA). All tumours were screened for BRAF activating mutations.

RESULTS

The BRAF mutation was more frequent in SSA (75%) and MP (89%) than in classical HP (19%), SA (20%), and AD (0%) (p<0.0001), and also in sporadic MSI-H cancers (76%) compared with HNPCC (0%) and sporadic non-MSI-H cancers (9%) (p<0.0001). The BRAF mutation was identified more often in CIMP-high serrated polyps (72%) and CIMP-high CRC (77%) than in CIMP-low (30%) and CIMP-negative (13%) polyps (p = 0.002) as well as CIMP-low (18%) and CIMP-negative (0%) CRC (p<0.0001).

CONCLUSIONS

The BRAF mutation was frequently seen in SSA and in sporadic MSI-H CRC, both of which were associated with DNA methylation. Sporadic MSI-H cancers may originate in SSA and not adenomas, and BRAF mutation and DNA methylation are early events in this "serrated" pathway.

Methylation patterns define two types of hyperplastic polyp associated with colorectal cancer

AIM

Hyperplastic polyps (HP) of the colorectum have traditionally been regarded as non-neoplastic lesions. Recent data implicate HP in the pathogenesis of colorectal cancers (CRC) characterised by extensive DNA methylation and microsatellite instability. The aim of this study was to identify morphological and molecular features that may characterise subtypes of HP with potential for neoplastic progression.

MATERIALS AND METHODS

HP (22) clustering around distal CRC (group I) were compared with HP (58) in subjects with hyperplastic polyposis (group II). DNA methylation was tested in methylated in tumour (MINT) loci (1, 2, 12, 31) and genes HPP1, MGMT, p14ARF, p16INK4a, and hMLH1.

RESULTS

Group II HP showed significantly more methylation than group I HP at all loci except MINT1 and MGMT. Group I showed the lowest frequency of DNA methylation but the highest frequency of K-ras mutation. Group II HP (termed HP variant) had the morphological features of the recently described "sessile serrated adenomas". Methylation of hMLH1 was found most frequently in group II polyps that included foci of dysplasia (7/10) and in no group I lesions.

CONCLUSION

The findings support the existence of morphological and molecular heterogeneity among HP and highlight a subset that is likely to have significant malignant potential.

APC mutation and tumour budding in colorectal cancer

AIM

To determine the frequency of tumour budding and somatic APC mutation in a series of colorectal cancers stratified according to DNA microsatellite instability (MSI) status.

MATERIAL/METHODS

Ninety five colorectal cancers were genotyped for APC mutation in the mutation cluster region (exon 15) and scored for the presence of tumour budding at the invasive margin in haematoxylin and eosin stained sections. A subset was immunostained for beta catenin and p16.

RESULTS

The frequency of both somatic APC mutation and tumour budding increased pari passu in cancers stratified as sporadic MSI high (MSI-H), hereditary non-polyposis colorectal cancer (HNPCC), MSI low (MSI-L), and microsatellite stable (MSS). Both budding and APC mutation were significantly less frequent in sporadic MSI-H cancers than in MSI-L or MSS cancers. Tumour buds were characterised by increased immunostaining for both beta catenin and p16.

CONCLUSION

Tumour budding is associated with an adverse prognosis. The lack of budding in MSI-H colorectal cancer may account for the improved prognosis of this subset and may be explained by an intact WNT signalling pathway and/or inactivated p16(INK4a).

Loss of p16 expression is associated with histological features of melanoma invasion

While mutations of CDKN2A are associated with melanoma predisposition, the precise role of its gene product p16 in the development of sporadic melanoma is less clearly understood. We sought to determine the prevalence of p16 expression using immunohistochemical analysis in a population-based sample of melanoma tumours, and also to identify histological, phenotypic and environmental factors associated with the presence or absence of p16 expression. We conducted face-to-face interviews with 108 patients newly diagnosed with melanoma to ascertain their history of sun exposure, and recorded various phenotypic parameters. Paraffin sections of tumours from these patients were stained with an anti-p16 monoclonal antibody following antigen retrieval. Overall, 52 (48%) tumours expressed p16; nodular melanomas had significantly lower levels of p16 immunoreactivity than superficial spreading melanomas (P = 0.015). While no association was found between p16 expression and host phenotype, loss of p16 staining was associated with thicker lesions (p = 0.084) and a high mitotic index (P = 0.013). Taken together, these findings are consistent with loss of p16 being a late event in the progression of sporadic primary melanomas, being associated with tumours of a more aggressive nature.

Occult axillary lymph node metastases in breast cancer do matter: results of 10-year survival analysis

Axillary lymph node status is one of the most powerful prognostic factors for patients with breast cancer and is often critical in stratifying patients into adjuvant treatment regimens. In 203 apparently node-negative cases of breast cancer, a combination of immunohistochemical staining and step-sectioning identified occult metastases in 25% of cases. Ten-year follow-up information is available for these patients. Histologic features of the primary tumor and immunohistochemical staining for estrogen receptor, progesterone receptor, Her-2, and p53 were also evaluated. With multivariate analysis, both occult metastases and higher histologic grade of the primary tumor were independent predictors of disease-free survival. Histologic grade was the only significant independent predictor of overall survival. Estrogen receptor, progesterone receptor, Her-2, and p53 status did not predict the presence of metastases or survival when all tumor types were considered together. Metastases >0.5 mm significantly predicted a poorer disease-free survival when invasive ductal carcinomas were considered alone. Histologic grade was significantly associated with disease-free survival in the premenopausal and perimenopausal patients but not in the postmenopausal patients. The presence of occult metastases approached significance for overall survival in the premenopausal and perimenopausal patients but not in the postmenopausal patients.

Distinction between familial and sporadic forms of colorectal cancer showing DNA microsatellite instability

Attempts to classify colorectal cancer into subtypes based upon molecular characterisation are overshadowed by the classical stepwise model in which the adenoma-carcinoma sequence serves as the morphological counterpart. Clarity is achieved when cancers showing DNA microsatellite instability (MSI) are distinguished as sporadic MSI-low (MSI-L), sporadic MSI-high (MSI-H) and hereditary non-polyposis colorectal cancer (HNPCC). Divergence of the 'methylator' pathway into MSI-L and MSI-H is at least partly determined by the respective silencing of MGMT and hMLH1. Multiple differences can be demonstrated between sporadic and familial (HNPCC) MSI-H colorectal cancer with respect to early mechanisms, evolution, molecular characterisation, demographics and morphology. By acknowledging the existence of multiple pathways, rapid advances in the fields of basic and translational research will occur and this will lead to improved strategies for the prevention, early detection and treatment of colorectal cancer.

Proliferation, apoptosis, and survival in high-level microsatellite instability sporadic colorectal cancer

Sporadic colorectal cancer (CRC) characterized by high-level DNA microsatellite instability (MSI-H) has a favorable prognosis. The reason for this MSI-H survival advantage is not known. The aim of this study was to correlate proliferation, apoptosis, and prognosis in CRC stratified by MSI status. The proliferative index (PI) was measured by immunohistochemical staining with the Ki-67 antibody in a selected series of 100 sporadic colorectal cancers classified according to the level of MSI as 31 MSI-H, 29 MSI-Low (MSI-L), and 40 microsatellite stable (MSS). The Ki-67 index was significantly higher in MSI-H cancers (P < 0.0001) in which the PI was 90.1 +/- 1.2% (mean +/- SE) compared with 69.5 +/- 3.1% and 69.5 +/- 2.3% in MSI-L and MSS subgroups, respectively. There was a positive linear correlation between the apoptotic index (AI) and PI (r = 0.51; P < 0.001), with MSI-H cancers demonstrating an increased AI:PI ratio indicative of a lower index of cell production. A high PI showed a trend toward predicting improved survival within MSI-H cancers (P = 0.09) but did not predict survival in MSI-L or MSS cancers. The AI was not associated with survival in any MSI subgroup. In conclusion, this is the first study to show that sporadic MSI-H cancers are characterized by a higher AI:PI ratio and increased proliferative activity compared with MSI-L and MSS cancers, and that an elevated PI may confer a survival advantage within the MSI-H subset.

CDKN2A is not the principal target of deletions on the short arm of chromosome 9 in neuroendocrine (Merkel cell) carcinoma of the skin

The majority of small-cell lung cancers (SCLCs) express p16 but not pRb. Given our previous study showing loss of pRb in Merkel cell carcinoma (MCC)/neuroendocrine carcinoma of the skin and the clinicopathological similarities between SCLC and MCC, we wished to determine if this was also the case in MCC. Twenty-nine MCC specimens from 23 patients were examined for deletions at 10 loci on 9p and 1 on 9q. No loss of heterozygosity (LOH) was seen in 9 patients including 2 for which tumour and cell line DNAs were examined. Four patients had LOH for all informative loci on 9p. Ten tumours showed more limited regions of loss on 9p, and from these 2 common regions of deletion were determined. Half of all informative cases had LOH at D9S168, the most telomeric marker examined, and 3 specimens showed loss of only D9S168. A second region (IFNA-D9S126) showed LOH in 10 (44%) cases, and case MCC26 showed LOH for only D9S126, implicating genes centromeric of the CDKN2A locus. No mutations in the coding regions of p16 were seen in 7 cell lines tested, and reactivity to anti-p16 antibody was seen in all 11 tumour specimens examined and in 6 of 7 cell lines from 6 patients. Furthermore, all cell lines examined reacted with anti-p14(ARF) antibody. These results suggest that neither transcript of the CDKN2A locus is the target of deletions on 9p in MCC and imply the existence of tumour-suppressor genes mapping both centromeric and telomeric of this locus.

Altered mucin expression in the gastrointestinal tract: a review

Early studies of changes in mucin expression in disorders of the gastrointestinal tract focused on alterations in the carbohydrate chain. This review briefly considers the various mechanisms by which such alterations may come about: (a) normal variation, (b) sialic acid alterations, (c) defective assembly of carbohydrate side-chains, (d) changed expression of core proteins and (e) epithelial metaplasia. The availability of monoclonal antibodies to mucin core proteins adds a new dimension to mucin histochemistry. It is now possible to offer explanations for traditional mucin histochemical findings on the basis of lineage-specific patterns of mucin core protein expression. Changes in core protein expression are described in inflammatory, metaplastic and neoplastic disorders of the gastrointestinal tract. The possibility that mucin change could be important in the aetiology of some diseases such as ulcerative colitis and H. pylori gastritis is considered. It is more probable, however, that changes in mucin expression are secondary to reprogramming of cellular differentiation and altered cell turnover. As such they may serve as markers to explain pathogenesis and provide novel diagnostic and prognostic information.

The role of a nurse case manager in implementing a critical pathway for infrainguinal bypass surgery

BACKGROUND

A previous study showed the effectiveness of a clinical pathway for infrainguinal bypass surgery in reducing postoperative length of stay (LOS) in an acute care setting. Most of the deviations from the pathway were due to patient factors (50%) and/or external disposition problems (30%), but 20% were related to physician or system problems that could potentially be modified. The current study examined those factors influencing LOS following infrainguinal bypass surgery and the impact of daily rounds by a nurse case manager--a vascular nurse specialist--on LOS and pathway deviations.

METHODS

Data were collected through detailed chart review and prospective tracking of pathway deviations. LOS was compared in 58 patients on the modified pathway (with the nurse case manager) to 69 patients on the original pathway and 67 prepathway controls. Multivariate analysis was used to identify factors influencing postoperative LOS and to compare LOS among the three groups.

RESULTS

Use of a nurse case manager significantly reduced physician-related deviations, from the pathway from 10% to 0% (p = .015), and reduced system-related deviations from 3% to 0%. Median postoperative LOS was 7 days before the pathway was begun, 6 days with the original pathway, and 5 days after the introduction of a vascular nurse specialist (p = .0001). There were no differences in rates of complications, rates of readmission, or mortality.

CONCLUSIONS

Intervention by a nurse case manager facilitated implementation of a critical pathway for patients undergoing infrainguinal bypass surgery, especially by preventing patient deviations due to intrainstitutional factors.

Tumour infiltrating lymphocytes and apoptosis are independent features in colorectal cancer stratified according to microsatellite instability status

BACKGROUND

The presence of high level DNA microsatellite instability (MSI-H) in colorectal cancer is associated with an improved prognosis, as is the presence of tumour infiltrating lymphocytes (TILs). It is not clear if TILs contribute directly to the survival advantage associated with MSI-H cancers through activation of an antitumour immune response.

AIMS

To correlate TIL and apoptosis rates in colorectal cancer stratified by MSI status.

METHODS

The distribution of TILs was characterised and quantified in a selected series of 102 sporadic colorectal cancers classified according to levels of MSI as 32 MSI-H, 30 MSI-low (MSI-L), and 40 microsatellite stable (MSS). Archival blocks were immunostained using the T cell markers CD3 and CD8, and the B cell marker CD20. Apoptosis of malignant epithelial cells was quantified by immunohistochemistry with the M30 CytoDEATH antibody.

RESULTS

Positive staining with anti-CD3 and negative staining with anti-CD20 identified virtually all TILs as T cells. The majority of CD3+ TILs (>75%) also stained with anti-CD8. TILs were most abundant in MSI-H colorectal cancers in which 23/32 (72%) scored as TIL positive. Only 5/40 (12.5%) MSS tumours and 9/30 (30%) MSI-L cancers were TIL positive (p<0.0001). MSI-H cancers showed a twofold higher rate of apoptosis (mean (SD) 3.52 (0.34)%) than the MSS cancers (1.53 (0.23)%) while the MSI-L subgroup had an intermediate level (2.52 (0.35)%) (p<0.0001). Overall, there was a small (r=0.347) but significant linear correlation between CD3+ and M30+ random apoptosis counts (p<0.001). However, TILs and apoptosis showed little colocalisation.

CONCLUSIONS

While TILs might be expected to explain the increased apoptotic rate and improved prognosis of MSI-H cancers, it is likely that TILs and apoptosis are independent characteristics of MSI-H cancers.

Methylation of O-6-methylguanine DNA methyltransferase characterizes a subset of colorectal cancer with low-level DNA microsatellite instability

The significance of low-level DNA microsatellite instability (MSI-L) is not well understood. K-ras mutation is associated with MSI-L colorectal cancer and with the silencing of the DNA repair gene O-6-methylguanine DNA methyltransferase (MGMT) by methylation of its promoter region. MGMT methylation was studied in sporadic colorectal cancers stratified as DNA microsatellite instability-high (n = 23), MSI-L (n = 44), and microsatellite-stable (n = 23). Methylation-specific PCR was used to detect MGMT-promoter hypermethylation in 3 of 23 (13%) microsatellite instability-high, in 28 of 44 (64%) MSI-L, and in 6 of 23 (26%) microsatellite-stable cancers (P = 0.0001). K-ras was mutated in 20 of 29 (69%) methylated MSI-L cancers and in 2 of 15 (13%) unmethylated MSI-L cancers (P = 0.001), indicating a relationship between MGMT-methylation and mutation of K-ras. Loss of nuclear expression of MGMT was demonstrated immunohistochemically in 23 of 31 (74%) cancers with methylated MGMT and in 10 of 49 (20%) cancers with nonmethylated MGMT (P < 0.0001). Loss of expression of MGMT was also demonstrated in 9 of 31 serrated polyps. Silencing of MGMT may predispose to mutation by overwhelming the DNA mismatch repair system and occurs with greatest frequency in MSI-L colorectal cancers.

Neoplastic progression occurs through mutator pathways in hyperplastic polyposis of the colorectum

AIM

Colorectal cancer has been described in association with hyperplastic polyposis but the mechanism underlying this observation is unknown. The aim of this study was to characterise foci of dysplasia developing in the polyps of subjects with hyperplastic polyposis on the basis of DNA microsatellite status and expression of the DNA mismatch repair proteins hMLH1, hMSH2, and hMSH6.

MATERIALS AND METHODS

The material was derived from four patients with hyperplastic polyposis and between one and six synchronous colorectal cancers. Normal (four), hyperplastic (13), dysplastic (13), and malignant (11) samples were microdissected and a PCR based approach was used to identify mutations at 10 microsatellite loci, TGFbetaIIR, IGF2R, BAX, MSH3, and MSH6. Microsatellite instability-high (MSI-H) was diagnosed when 40% or more of the microsatellite loci showed mutational bandshifts. Serial sections were stained for hMLH1, hMSH2, and hMSH6.

RESULTS

DNA microsatellite instability was found in 1/13 (8%) hyperplastic samples, in 7/13 (54%) dysplastic foci, and in 8/11 (73%) cancers. None of the MSI-low (MSI-L) samples (one hyperplastic, three dysplastic, two cancers) showed loss of hMLH1 expression. All four MSI-H dysplastic foci and six MSI-H cancers showed loss of hMLH1 expression. Loss of hMLH1 in MSI-H but not in MSI-L lesions showing dysplasia or cancer was significant (p<0.001, Fisher's exact test). Loss of hMSH6 occurred in one MSI-H cancer and one MSS focus of dysplasia which also showed loss of hMLH1 staining.

CONCLUSION

Neoplastic changes in hyperplastic polyposis may occur within a hyperplastic polyp. Neoplasia may be driven by DNA instability that is present to a low (MSI-L) or high (MSI-H) degree. MSI-H but not MSI-L dysplastic foci are associated with loss of hMLH1 expression. At least two mutator pathways drive neoplasia in hyperplastic polyposis. The role of the hyperplastic polyp in the histogenesis of sporadic DNA microsatellite unstable colorectal cancer should be examined.

Mucin core protein expression in colorectal cancers with high levels of microsatellite instability indicates a novel pathway of morphogenesis

Particular mucinous phenotypes have been associated with serrated epithelial polyps of the colon. These polyps also show a high frequency of DNA instability. The aim of this study was to examine the expression of mucins in colorectal cancers that arise through the suppressor and mutator pathways. The immunohistochemical distribution of the human apomucins MUC1, MUC2, MUC4, and MUC5AC was determined in 93 sporadic colorectal cancers classified previously (J. R. Jass et al., J. Clin. Pathol., 52: 455-460, 1999) according to levels of DNA microsatellite instability (MSI) as 22 MSI-high (MSI-H), 24 MSI-low (MSI-L), and 47 MS stable (MSS). MUC2 expression was observed in 19 (86%) MSI-H, 10 (42%) MSI-L, and 15 (32%) MSS cancers (P = 0.0001); and MUC5AC expression was observed in 17 (77%) MSI-H, 8 (33%) MSI-L, and 13 (28%) MSS cancers (P = 0.0003). There was no association between MUC1 or MUC4 expression and MSI status. The mucinous phenotype described in serrated polyps (MUC2+/MUC5AC+) was seen in 15 (68%) of 22 MSI-H and only 10 (14%) of 71 MSI-L/MSS cancers (P < 0.0001). Increased expression of the secretory mucins MUC2 and MUC5AC was observed in sporadic MSI-H cancers. Identical mucin changes and DNA MSI occurred in serrated polyps of the colorectum, which suggests that these lesions may represent precursors of MSI-H cancers.

p73 is up-regulated in a subset of hepatocellular carcinomas

Loss of heterozygosity (LOH) at 1p36 occurs in a number of solid tumors including hepatocellular carcinoma (HCC). Recently, a novel gene, p73, has been identified at 1p36.33. p73 is structurally and functionally related to p53 located at 17p13.1, which is a target for inactivation in HCCs. p73 produces at least two splicing variants, p73alpha and beta, and a polymorphism in exon 2 results in two alleles, GC or AT. Initially, only the AT allele and p73alpha transcripts were identified in malignant cell lines, suggesting a role for these in the malignant phenotype. The aims of this study were to determine the extent of LOH at 1p36 and 17p13.1 in HCCs from Australia and South Africa, and to identify patterns of p73 mRNA and p73 and p53 protein expression. LOH at 1p36 was found in 8 of 25 Australian and 6 of 10 South African cases. p73 mRNA expression occurred in 8 HCCs, but not in nonmalignant liver tissue. Two of these 8 HCCs had LOH of 1p36. Both alpha and beta transcripts were observed in GC/GC homozygotes and GC/AT heterozygotes. No p73 protein expression was observed by immunohistochemistry in nonmalignant liver tissue or in HCC. p53 inactivation appeared to be associated with up-regulation of p73 expression, suggesting a compensatory role for p73 in this situation. The LOH at 1p36 implies a liver-specific tumor suppressor gene is in this region. However, the up-regulation of p73 mRNA suggests p73 is not the target of this loss.

Adenocarcinoma of colon differentiating as dome epithelium of gut-associated lymphoid tissue

AIMS

An early adenocarcinoma of the ascending colon was confined to a mass of gut-associated lymphoid tissue (GALT). The first description of an adenocarcinoma of colon differentiating as dome epithelium is presented.

METHODS AND RESULTS

A plaque-like carcinoma was identified opposite the ileocaecal valve in an asymptomatic 56-year-old man with a family history of colorectal cancer. Malignant epithelium was confined to a mass of GALT filling but limited to the submucosa. Characterization of the neoplasm was undertaken by means of mucin histochemistry, immunohistochemistry, electron microscopy and assessment of DNA microsatellite instability status. The malignant epithelium comprised well differentiated columnar cells with a microvillous brush border and expressing MUC1, but no goblet cells or expression of MUC2. The demonstration of focal clusters of intraepithelial B-lymphocytes supported the presence of functioning M-cells within the malignant neoplasm. The cancer was DNA microsatellite stable despite the finding of tumour infiltrating lymphocytes.

CONCLUSIONS

There is evidence for the origin of colorectal neoplasia from dome epithelium in both experimental models and microreconstruction studies of early adenomas in nonpolypotic human colorectal mucosa. It is suggested that the lymphocyte-rich subset of colorectal cancer that expresses MUC1 but not MUC2 may be differentiating as dome epithelium of gut-associated lymphoid tissue.