Long non-coding antisense RNA KRT7-AS is activated in gastric cancers and supports cancer cell progression by increasing KRT7 expression

Alterations in long non-coding RNAs (lncRNAs) are associated with human carcinogenesis. One group of lncRNAs, which are antisense in orientation to coding mRNAs (ASs), have been recently described in cancers but are poorly understood. We sought to identify ASs involved in human gastric cancer (GC) and to elucidate their mechanisms of action in carcinogenesis. We performed massively parallel RNA sequencing in GCs and matched normal tissues, as well as in GC-derived and normal gastric epithelial cell lines. One AS, designated Homo sapiens keratin 7 (KRT7-AS), was selected due to its marked upregulation and concordant expression with its cognate sense counterpart, KRT7, in GC tissues and cell lines. KRT7-AS formed an RNA-RNA hybrid with KRT7 and controlled KRT7 expression at both the mRNA and the post-transcriptional levels. Moreover, forced overexpression of the KRT7-overlapping region (OL) of KRT7-AS (but not its non-KRT7-OL portions) increased keratin 7 protein levels in cells. Finally, forced overexpression of full-length KRT7-AS or OL KRT7-AS (but not its non-KRT7-OL regions) promoted GC cell proliferation and migration. We conclude that lncRNA KRT7-AS promotes GC, at least in part, by increasing KRT7 expression.

MicroRNA-192 and -215 are upregulated in human gastric cancer in vivo and suppress ALCAM expression in vitro

The dismal outcome of gastric cancer patients highlights the need for diagnostic biomarkers and effective therapeutic targets, such as microRNAs. We sought to discover microRNAs involved in gastric cancer, and to elucidate their downstream target mechanisms. Both cultured gastric epithelial cells (HFE145 and NCI-N87) and primary human gastric tissues (31 non-neoplastic stomach (NS) and 25 gastric carcinomas (GC)) were studied. MicroRNA microarrays and quantitative RT-PCR were applied to discover and verify differentially expressed microRNAs. in vitro cell migration and invasion, cell proliferation, cell cycle and apoptosis assays were executed to elucidate biological effects of microRNA-192 and -215. Western blotting and luciferase assays were performed to confirm direct messenger RNA targeting by microRNA-192 and -215. MicroRNA microarray analyses revealed that 25 and 20 microRNAs were upregulated and downregulated in GC vs NS, respectively. Expression levels of both microRNA-192 and -215 were significantly higher in GC than in NS (P<0.05). Luciferase assays suggested that microRNA-215 inhibits activated leukocyte cell adhesion molecule (ALCAM) expression at the posttranscriptional level. In addition, expression levels of ALCAM were significantly lower in GC than in NS. Mimics and inhibitors, respectively, of microRNA-192 or -215 exerted no effect on cell cycle or apoptosis in the immortalized normal gastric cell line HFE145 or the gastric cancer cell line NCI-N87. However, mimics of microRNA-192 or -215 significantly increased growth rates in HFE145 cells, whereas inhibitors of microRNA-192 or -215 caused significant decreases in growth rates in NCI-N87 cells. ALCAM knockdown by an ALCAM-specific siRNA significantly increased cell growth in HFE145 cells. Both transfection of mimics of microRNA-192 or -215 and ALCAM knockdown by an ALCAM-specific siRNA significantly increased the migration of HFE145 cells. In conclusion, in gastric cancer, both microRNA-192 and -215 are overexpressed in vivo and exert cell growth and migration-promoting effects in vitro, thus representing potential microRNAs with a role in cancer in the human stomach.

THE CHARACTER OF THE PNEUMONIC LESIONS PRODUCED BY INTRABRONCHIAL INSUFFLATION OF VIRULENT STREPTOCOCCI

Comparing the pneumonic lesions produced by this very virulent streptococcus with those caused by a mildly virulent strain of the same organism, we find that with one exception the differences between them are only of a quantitative nature and not striking. There are the same intense leucocytic exudation into the alveoli and the leucocytic infiltration of the framework of the lungs. Macroscopically the pneumonia produced by the virulent organism was, as a rule, lobular in character. Occasionally, however, especially when large doses of the culture had been given, the gross appearance of the lesion gave the impression of a lobar pneumonia. But even in these cases the cut surface showed that the solid areas were separated by softer and lighter areas of aerated, congested, or edematous lung substance. Pleurisy was practically absent from the lungs in this series of experiments; only one case showed a narrow strip of fibrinous exudate on the pleura. Although in some instances large doses of the cultures were given and some dogs were permitted to live six or seven days, there was no mortality among the dogs in these experiments, just as there had been none among the animals experimented upon with the streptococcus of very low virulence. The course of the pneumonia caused by the virulent organism seemed to be somewhat longer than that produced by the less virulent one; areas of resolving pneumonia were found to persist on the sixth and seventh days after the injection, and in one such instance the solid focus contained viable organisms. There was some difference in the amount of fibrin present in the exudate caused by the two strains of streptococci. Although even in these experiments the amount of fibrin present was less than that found in the lesion produced by the virulent pneumococcus, it was perceptibly larger than the very small amount found in the lesions caused by the less virulent strain of streptococcus. It should be mentioned that there was no difference in the degree of phagocytosis observed in these two series of experiments. It was not marked in either case. One point of difference in the two series was noted: during the first forty-eight hours after insufflation of the virulent strain of streptococcus the blood of the animals obtained from the jugular vein during life and from the heart after death contained living organisms, while in the experiments with the slightly virulent streptococcus no living cocci were recovered from the blood. The virulence of the strain of streptococcus employed in the present investigation was, as has been pointed out, similar to that of the pneumococcus employed in the investigation of Lamar and Meltzer and in many of our own experiments, as far as mice were concerned, since both killed mice weighing fifteen grams in doses of 0.000,001 of a cubic centimeter in twenty-four to thirty-six hours. The findings in the lesions caused by these two organisms are comparable and therefore some deductions may be drawn regarding the similarity or dissimilarity of their actions. One of the first things we wish to bring out is the correction of our former statement regarding the presence of the cocci in the blood. As our new investigation shows, there is evidently no difference in this respect between the streptococcus and the pneumococcus. When both organisms are highly virulent they can be found in the circulating blood of the living dog or in the heart's blood of the dead dog during the first twenty-four or forty-eight hours after an intrabronchial insufflation. On the other hand, the present investigation rather confirms in a general way our first contention that the pneumonic lesions produced by the two different organisms differ distinctly in many ways. There is the difference in the mortality; even with fairly large quantities of the culture of the virulent streptococcus the mortality was nil in this series, although some of the dogs were kept alive for six and seven days. The mortality of the pneumococcus infection depends upon the quantity insufflated and may amount, as Lamar and Meltzer pointed out, to 16 per cent. The gross appearance of the lesion produced by the pneumococcus is, as frequently stated, that of a lobar pneumonia, frequently accompanied by a fibrinous exudate on the pleura. The gross appearance of the lesion produced even by a virulent streptococcus is, as a rule, that of a lobular pneumonia and is practically never accompanied by pleurisy. In the few instances in which large quantities of the streptococcus were given and the outward appearance of the lungs approached that of a lobar pneumonia, it was found that on section of the consolidated lung the solid foci proved to be separated by lighter areas of aerated, congested lung. In the lesions produced by the virulent streptococci the walls of the finer bronchi and the framework of the lung were markedly infiltrated with leucocytes, while in the lobar pneumonia produced by the pneumococcus the framework remained free from such infiltration. Finally there is the unmistakable difference in the amount of fibrin present in the alveolar exudate. While in the exudate of the lesion produced by the virulent streptococcus the amount was perceptibly larger than the insignificant amount present in the lesion caused by a slightly virulent strain, it is not to be compared with the large amount of fibrin which exists in the exudate of pneumococcus pneumonia. The several investigations which we have carried out seem to show conclusively that in general the streptococcus causes a lobular pneumonia which, besides the leucocytic intra-alveolar exudation, is characterized by a leucocytic infiltration of the lung framework, and that the pneumococcus causes a lobar pneumonia, which is practically free from leucocytic infiltration of the interstitial tissue of the lung. Furthermore, a virulent pneumococcus causes a lesion in which fibrin is a prominent element in the exudate and that element distinguishes the exudate sharply from the exudate of the lesion caused by a virulent streptococcus in which fibrin is present only in moderate amount. It distinguishes it in a still more striking manner from the exudates of the lesions caused by non-virulent pneumococci or streptococci, in which fibrin is present only in very small amounts. It seems that the formation of fibrin is connected in some specific way with the pneumococcus on the one hand, and with the virulence of the organism on the other. For even with the relatively small amounts of fibrin present in the exudates of lesions caused by the streptococcus there is a perceptible difference in the quantity according to the virulence of the organism. Whether fibrin is a means which enhances virulence, or whether it is a reaction product against it, our experiments so far do not entitle us to discuss.

THE EFFECTS OF INTRASPINAL INJECTION OF MAGNESIUM SALTS UPON TETANUS

Intraspinal injections of magnesium sulphate, in doses which do not affect the respiratory centre or other vital function, are capable of abolishing completely all clonic convulsions and tonic contractions in cases of human tetanus, and experimental tetanus in monkeys. The relaxing effects of the injections may last twenty-four hours or longer. In experimental tetanus in monkeys early intraspinal injections of magnesium salts are capable of retarding the progress and development of the tetanic symptoms.

AN EXPERIMENTAL STUDY OF THE ADDITIVE AND ANTAGONISTIC ACTIONS OF SODIUM OXALATE, AND SALTS OF MAGNESIUM AND CALCIUM IN THE RABBIT

The foregoing experiments establish firmly the following facts. Subcutaneous or intramuscular injections of sodium oxalate in subtoxic doses, when administered to an animal which received a subminimal dose of magnesium sulphate, produce profound anesthesia and paralysis of long duration, although the usual effects of sodium oxalate alone are of a stimulating character. This fact is, in general, in harmony with the results reported by Starkenstein who, however, seems to have used the combination of the two salts in one solution; namely, that of magnesium oxalate. The combined injections of subminimal doses of sodium oxalate and magnesium sulphate produce a strong reduction, or even, at times, a complete abolition of the conductivity of the motor nerve endings. An intravenous injection of calcium salts brings on a recovery from the profound and prolonged effects of the combined action of sodium oxalate and magnesium sulphate, which is as prompt as is observed in experiments in which effective doses of magnesium alone were given. This fact is the more noteworthy, since depressions of long duration produced by prolonged continuous injections of magnesium solutions alone do not respond very promptly and effectively to calcium injections. As will be recalled, the starting point for our investigation was the hypothesis that substances which are capable of precipitating calcium—a biological antagonist of magnesium—ought to be capable of increasing the depressive effect of magnesium. Our experiments proved that this assumption was correct. This would seem, therefore, to justify the interpretation that the augmenting action of sodium oxalate has its cause in the ability of the latter to precipitate calcium and thus increase within the body the amount of unantagonized magnesium. However, we wish to state expressly that this view is, for the present, still no more than a hypothesis and does not exclude other possible interpretations of our facts. As we pointed out it speaks against this hypothesis that oxalates do not produce phenomena of depression; the toxic symptoms produced by oxalates exhibit distinctly signs of increased and not of decreased irritability.

PNEUMONIC LESIONS MADE BY INTRABRONCHIAL INSUFFLATION OF NON-VIRULENT PNEUMOCOCCI

The intrabronchial insufflation of a non-virulent pneumococcus causes, like the insufflation of a virulent pneumococcus, the development of an exudate in the lungs which, in general, leaves the framework unaffected, and the lesion presents the gross appearance of a lobar pneumonia. It differs, however, materially from the pneumonia produced by virulent pneumococci in the important points that the consolidation tends to a more rapid resolution, the disease is non-fatal, the blood is not invaded by the organism, and the exudate is strikingly poor in fibrin. As to the question which was the starting point for the foregoing investigation, namely, whether the pneumonic lesion produced by the streptococcus is merely a form of pneumonia caused by a less virulent organism, it may be answered for the dog, it seems, in the negative. The leucocytic infiltration of the framework of the lungs which occurs invariably in streptococcus pneumonia, and which is practically absent in the lesions caused by the virulent as well as by the non-virulent pneumococcus, is a strong enough feature to form a dividing line between the two forms of experimental pneumonia previously described.

EFFECT OF INTRABRONCHIAL INSUFFLATION OF SOLUTIONS OF SOME INORGANIC SALTS

Intrabronchial injections of isotonic as well as of hypotonic solutions of sodium chloride or even of distilled water cause no pulmonary lesions. Intrabronchial injections of mercuric chloride even in a dilution of 1:10,000 cause a marked pulmonary lesion. The lesion is not of an inflammatory character; it consists of congestion, formation of thrombi, and hemorrhage. Intrabronchial injections of hypertonic solutions of sodium chloride as well as of sodium sulfate cause, in most instances, no lesions whatsoever. In a smaller number of cases in which moderate lesions were present they may have been due either to a previous infection (distemper) or to some predisposing cause (winter months). Intrabronchial injection of magnesium salts apparently tends to cause moderate pulmonary lesions (bronchopneumonia). This seems especially true of magnesium sulfate.

THE INTRAVENOUS INJECTION OF MAGNESIUM SULPHATE FOR ANESTHESIA IN ANIMALS

These experiments justify the following general conclusions. By the intravenous injection of M/4 magnesium sulphate into dogs at a certain rate, a stage can be reached where the abdominal walls are completely relaxed and when section of the abdomen and stimulation of sensitive parts of the parietal peritoneum do not produce pain or elicit any reaction of the animal. At the same time spontaneous respiration may still be maintained within normal limits and the lid reflex be fair or even normal. In this stage intratracheal intubation for artificial respiration can be easily accomplished. This stage may be attained in 12 to 14 minutes when the rate of injection is about 3 cc. per minute. When this stage is once attained the rate of injection should gradually be reduced, otherwise, sooner or later, spontaneous respiration will be abolished, and by a further maintenance of the rate of injection all the skeletal muscles may become paralyzed. When the injection of magnesium is continued for a longer period, the paralytic effects of the magnesium injection will set in, even when administered at a slow rate. The paralysis of the respiratory function is readily met by intrapharyngeal insufflation, which is easily executed even without training in this procedure, or by the method of intratracheal insufflation, if executed by one trained in its management. When the respiration of the animal is accomplished by insufflation, the paralytic effect of the magnesium may be abolished fairly rapidly by an intravenous injection of about 10 cc. of an M/8 calcium chloride solution; or it may disappear slowly, after the infusion of the magnesium solution is discontinued for some time. The latter mode of disappearance may be favorably accelerated by an intravenous infusion of 60 to 100 cc. of an M/4 solution of sodium sulphate. The production of anesthesia by intravenous injection of magnesium sulphate should not be undertaken unless an apparatus for intrapharyngeal insufflation is at hand, because in exceptional cases the disappearance of spontaneous respiration may be one of the earliest consequences of the magnesium injection. The injection of calcium chloride should not be employed in cases in which the subject shows cardiac insufficiency. In such instances, moreover, injections of magnesium should not be used for the purpose of anesthesia; at least not until greater experience has been acquired in the employment of this method.

EXPERIMENTAL BRONCHOPNEUMONIA BY INTRABRONCHIAL INSUFFLATION

When intrabronchial insufflation of pure cultures of the streptococcus or of the influenza bacillus is properly carried out, it produces without fail a pneumonic lesion. This lesion is similar in its nature to the one known in human pathology as bronchopneumonia, and differs materially from the pneumonic lesion produced experimentally by the intrabronchial insufflation of pure cultures of the pneumococcus. Considering the fact that none of the dogs used in the experiments with the pneumococcus and none of those used in the present investigation were selected or prepared in any way, the conclusion seems to be unavoidable that the proper invasion of the microörganism is the determining factor in the development of pneumonia, the condition of the animal being only a minor element in this regard. Furthermore, since different organisms introduced in the same way and under conditions which are apparently the same produced distinctly different pneumonic lesions in animals of the same species, the further conclusion presents itself that the different types of pneumonia are produced by specifically different bacteria. However, further investigation may show that the differences in the nature of the lesion are due rather to the degree of virulence of the causative microörganism than to differences in the species; that is, that different lesions may possibly be produced by organisms of the same species, provided they possess different degrees of virulence. Further experimentation may also show that the condition of the animal and of the affected organ which, in the onset and development of the pneumonic disease, is, perhaps, unimportant, may be the leading factor in determining the course and outcome of the disease.

THE RESPIRATORY CHANGES OF PRESSURE AT THE VARIOUS LEVELS OF THE POSTERIOR MEDIASTINUM

The changes of the respiratory pressure within the esophagus, as well as within the posterior mediastinum, differ greatly in their various levels. They are best in the section between the heart and the diaphragm; they are moderate from the upper aperture of the thorax to above the tracheal bifurcation, and they are. very much reduced in the region of the bifurcation and the heart. In the latter case the normal respiratory changes are reduced in their transmission to the mediastinum by the intervention of the inelastic tissues of the bifurcation and the heart. The difference in the changes of the respiratory pressure between the low^er and the upper part of the mediastinum is due to a difference in the respiratory changes of pressure between the lower and upper parts of the lungs. The changes in the respiratory pressure which begin in the lower part of the lungs lose some of their force on their way to the apices of. the lungs. In artificial respiration by intratracheal insufflation there is no difference in the respiratory pressures between the upper and the lower parts of the lungs. This investigation supports the view, frequently entertained by clinicians, that the respiratory changes in the apices of the lungs are not as good as those of the rest of the lungs, and it disproves the claim of some physiologists that a decrease or increase of pressure at any part of the lungs must be equally distributed through all parts of the lungs, a claim based upon merely a priori physical considerations.

EXPERIMENTAL PNEUMONIA BY INTRABRONCHIAL INSUFFLATION

The numerous attempts made in the last twenty-five years to reproduce lobar pneumonia in animals practically failed in all instances. By intrabronchial insufflation of pure cultures of pneumococcus in dogs, we produced experimental pneumonia successively in forty-two cases, with a mortality of at least 16 per cent. The fatal cases resembled closely lobar pneumonia in man. In the non-fatal cases, the pathological and bacteriological findings were again in accord with the findings in man. Clinically, however, the cases of nonfatal experimental pneumonia run a milder and shorter course than in man. In a few instances, lobar pneumonia has been produced experimentally also with the Pneumococcus mucosus and with Friedländer's pneumobacillus. The anatomical findings in these experiments have shown some characteristics agreeing with the findings in the pneumonias of man produced by these organisms. The quantity of the injected culture seemed to have a definite influence upon the outcome of the disease; in the fatal cases larger quantities of the culture had been injected. The animals were neither selected nor prepared in any manner. The experimental success did not, therefore, appear to depend upon the degree of resistance of the individual hosts. It is suggested that the uniformly successful results of the experiments were due to the obliteration of a large number of bronchi by the injected culture, through which mechanical effect a favorable opportunity was provided the pneumococci to develop and display their pathogenic activities consisting in the calling forth of a characteristic local, more or less effective, widespread, inflammatory reaction of the lung tissue.

THE RELATION OF THE RATE OF ABSORPTION OF ADRENALIN TO ITS GLYCOSURIC AND DIURETIC EFFECTS

Subcutaneous injections of adrenalin are, in contrast with its behavior in the production of the other effects of that drug, more favorable to the production of glycosuria in rabbits than intramuscular injections; the failures are fewer and the quantities of dextrose in the urine are generally larger. In general, as regards the stimulation of diuresis by adrenalin, a subcutaneous injection exerts generally a greater effect than an intramuscular one. Subcutaneous injections of a certain dose of adrenalin distributed over several areas are far less effective than the administration of that dose in a single injection; they fail frequently to produce any glycosuria, the quantity of dextrose in the urine, when present, being less, and the quantity of urine being generally diminished. Apparently the more slowly the injected adrenalin reaches the blood, the greater is its effect in producing glycosuria and generally, also, the greater its diuretic action.

Following in mother's footsteps? Mother-daughter risks for insulin resistance and cardiovascular disease 15 years after gestational diabetes

AIMS

To determine effects on mothers and daughters of gestational diabetes mellitus/gestational impaired glucose tolerance (GDM/GIGT) on their future metabolic and cardiovascular risks.

METHODS

Case mothers who had GDM/GIGT in pregnancy (cases; n = 90) and normoglycaemic control women (n = 99) and their daughters underwent lifestyle assessment and metabolic tests 15-years post-partum.

RESULTS

Prevalence of glucose intolerance (GI) in daughters was 1.1%. Maternal prevalence was 44.4% in cases compared to 13.1% in controls, with conversion best predicted by weight gain. Case daughters had higher insulin resistance (IR) and greater waist circumference (WC) (51.2%) relative to control daughters (36.4%, p < 0.05) made worse if case mothers became GI at follow-up (65%) (relative risk =1.8; 95% confidence interval 1.2-2.9). In multivariable linear regression analyses adjusting for daughters' birthweight, maternal obesity (> 30.0 kg/m(2)) at 15years and mothers' case-control status were strong predictors of daughters' WC (p < 0.01; P < 0.01, respectively). For daughters' body mass index (BMI) percentile and percentage of body fat, maternal obesity was a stronger predictor (p < 0.01; p < 0.001)) than mothers' case-control status (p < 0.01; P = 0.09).

CONCLUSIONS

GDM/GIGT pregnancies led to increased conversion to GI in mothers, minimal in daughters. Case daughters have increased risk of central adiposity and insulin resistance, whereas maternal obesity strongly predicted daughters' BMI percentile and per cent of body fat. Controlling hyperglycaemia in pregnancy and family weight management may provide the key to preventing offspring obesity and glucose intolerance post GDM/GIGT.

Hypermethylation of the nel-like 1 gene is a common and early event and is associated with poor prognosis in early-stage esophageal adenocarcinoma

The nel-like1 (NELL1) gene maps to chromosome 11p15, which frequently undergoes loss of heterozygosity in esophageal adenocarcinoma (EAC). NELL1 promoter hypermethylation was examined by real-time methylation-specific polymerase chain reaction in 259 human esophageal tissues. Hypermethylation of this promoter showed highly discriminative receiver-operator characteristic curve profiles, clearly distinguishing esophageal squamous cell carcinoma (ESCC) and EAC from normal esophagus (NE) (P<0.001). NELL1 normalized methylation values were significantly higher in Barrett's metaplasia (BE), dysplastic Barrett's (D) and EAC than in NE (P<0.0000001). NELL1 hypermethylation frequency was zero in NE but increased early during neoplastic progression, to 41.7% in BE from patients with Barrett's alone, 52.5% in D and 47.8% in EAC. There was a significant correlation between NELL1 hypermethylation and BE segment length. Three (11.5%) of 26 ESCCs exhibited NELL1 hypermethylation. Survival correlated inversely with NELL1 hypermethylation in patients with stages I-II (P=0.0264) but not in stages III-IV (P=0.68) EAC. Treatment of KYSE220 ESCC and BIC EAC cells with 5-aza-2'-deoxycytidine reduced NELL1 methylation and increased NELL1 mRNA expression. NELL1 mRNA levels in EACs with an unmethylated NELL1 promoter were significantly higher than those in EACs with a methylated promoter (P=0.02). Promoter hypermethylation of NELL1 is a common, tissue-specific event in human EAC, occurs early during Barrett's-associated esophageal neoplastic progression, and is a potential biomarker of poor prognosis in early-stage EAC.

Transcriptional profiling suggests that Barrett's metaplasia is an early intermediate stage in esophageal adenocarcinogenesis

To investigate the relationship between Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC), we determined gene expression profiles of discrete pathological stages of esophageal neoplasia using a sequence-verified human cDNA microarray. Fifty one RNAs, comprising 24 normal esophagi (NE), 18 BEs, and nine EACs were hybridized to cDNA microarrays. Five statistical analyses were used for the data analysis. Genes showing significantly different expression levels among the three sample groups were identified. Genes were grouped into functional categories based on the Gene Ontology Consortium. Surprisingly, the expression pattern of BE was significantly more similar to EAC than to NE, notwithstanding the known histopathologic differences between BE and EAC. The pattern of NE was clearly distinct from that of EAC. Thirty-six genes were the most differentially modulated, according to these microarray data, in BE-associated neoplastic progression. Twelve genes were significantly differentially expressed in cancer-associated BE's plus EAC (as a single combined tissue group) vs noncancer-associated BE's. These genes represent potential biomarkers to diagnose EAC at its early stages. Our results demonstrate that molecular events at the transcriptional level in BE are remarkably similar to BE's-associated adenocarcinoma of the esophagus. This finding alarmingly implies that BE is biologically closer to cancer than to normal esophagus, and that the cancer risk of BE is perhaps higher than we had imagined. These findings suggest that changes modulated at the molecular biologic level supervene earlier than histologic changes, and that BE is an early intermediate stage in the process of EAC.

E2F-4 mutation in hereditary non-polyposis colorectal cancer

Defects in the DNA mismatch repair function are known to cause microsatellite instability (MSI) in hereditary non-polyposis colorectal cancer (HNPCC) as well as in a subset of sporadic colorectal cancer (CRC). We previously reported that the E2F-4 gene, which encodes an important transcription factor in cell cycle control, had frequent tumor-specific mutations at a coding region of trinucleotide microsatellite (CAG)n in a subset of human sporadic CRC with high-frequency MSI (MSI-H). In this study, we assessed mutations of E2F-4 in HNPCC as well as other target genes of defective DNA mismatch repair function. Eighteen colorectal cancer (CRC) patients from 13 kindreds meeting the Amsterdam criteria for HNPCC were analyzed and compared to sporadic CRC patients with MSI-H. We detected mutations of E2F-4 at the same repeat sequence in HNPCC. The frequency of the E2F-4 mutation in HNPCC was comparable with that in sporadic CRC with MSI-H. E2F-4 was considered to be one of the important target genes responsible for the carcinogenesis of HNPCC.

Global gene expression profiling in Barrett's esophagus and esophageal cancer: a comparative analysis using cDNA microarrays

In order to identify and contrast global gene expression profiles defining the premalignant syndrome, Barrett's esophagus, as well as frank esophageal cancer, we utilized cDNA microarray technology in conjunction with bioinformatics tools. We hybridized microarrays, each containing 8000 cDNA clones, to RNAs extracted from 13 esophageal surgical or endoscopic biopsy specimens (seven Barrett's metaplasias and six esophageal carcinomas). Hierarchical cluster analysis was performed on these results and displayed using a color-coded graphic representation (Treeview). The esophageal samples clustered naturally into two principal groups, each possessing unique global gene expression profiles. After retrieving histologic reports for these tissues, we found that one main cluster contained all seven Barrett's samples, while the remaining principal cluster comprised the six esophageal cancers. The cancers also clustered according to histopathological subtype. Thus, squamous cell carcinomas (SCCAs) constituted one group, adenocarcinomas (ADCAs) clustered separately, and one signet-ring carcinoma was in its own cluster, distinct from the ADCA cluster. We conclude that cDNA microarrays and bioinformatics show promise in the classification of esophageal malignant and premalignant diseases, and that these methods can be applied to small biopsy samples.

Activation of a cryptic splice site of PTEN and loss of heterozygosity in benign skin lesions in Cowden disease

Cowden disease is an autosomal dominant syndrome characterized by facial trichilemmomas, acral keratoses, papillomatous papules, mucosal lesions, and an increased risk for breast and nonmedullary thyroid cancer. Here, we describe a novel PTEN splicing site mutation in a family with classical Cowden disease and we studied benign skin lesions typical for Cowden disease for loss of heterozygosity. We found a PTEN IVS2 + 1G > Alpha 5'-splicing acceptor mutation resulting in activation of a cryptic splice site. Activation of this cryptic splice site is predicted to result in a frameshift with a premature stop codon, thus disrupting the phosphatase core motif of PTEN. Loss of heterozygosity analysis of two trichilemmomas, one fibroma, and three acanthomas of the index patient demonstrated loss of heterozygosity at the PTEN locus in four of these lesions. In conclusion, our data demonstrate that a PTEN splicing site mutation causes activation of a cryptic splice site, which results in aberrant transcripts.

Glypican-3 expression in Wilms tumor and hepatoblastoma

BACKGROUND

Glypican-3 (GPC3) is a heparan sulfate proteoglycan. When it is disrupted, it causes the X-linked gigantism-overgrowth Simpson-Golabi-Behmel syndrome. Its involvement in growth control is consistent with recent reports that it can bind to growth factors, possibly including insulin-like growth factor 2. Further, it has been hypothesized that it may function as a tumor suppressor gene in breast and ovarian carcinomas and mesotheliomas.

PATIENTS AND METHODS

RNA and protein were extracted from Wilms tumor and hepatoblastoma tissue samples and GPC3 levels were measured in these extracts by Northern blotting, reverse transcription polymerase chain reaction, and immunoblotting.

RESULTS

In contrast to published results with carcinomas, high levels of GPC3 expression were found in Wilms tumor and hepatoblastoma. Low or undetectable expressions of this gene were found in normal tissue surrounding the tumor.

CONCLUSIONS

Increased expression of GPC3 in Wilms tumor and hepatoblastoma suggests a growth-promoting or neutral activity for this gene product rather than a growth-suppressive effect.

Effect of naturally occurring E2F-4 alterations on transcriptional activation and proliferation in transfected cells

E2F is a family of transcription factors implicated in the regulation of gene expression required for progression through the G(1)-S transition. We have previously detected tumor-specific mutations at a trinucleotide repeat coding sequence of E2F-4 gene in a subset of human sporadic colorectal cancers. The purpose of this study was to investigate the potential functional consequences of these E2F-4 mutations. We transfected NIH3T3 fibroblasts with expression constructs containing wild-type as well as mutant E2F-4 cDNA, and the effect of the E2F-4 mutations on proliferation was examined. Alteration in transactivation of the E2F consensus promoter sequence was also examined by transient cotransfection of a E2F-4 with a DP-2 construct into cultured human cells. Transfected cell clones overexpressing mutant E2F-4 grew more rapidly and showed higher proliferative activity by increased immunohistochemical staining for proliferating cell nuclear antigen (PCNA). All three mutant forms of E2F-4 showed elevated transactivation of the E2F consensus promoter sequence. Thus, expression of mutant E2F-4s confers a growth advantage in vivo, and this effect may be related to the acquisition of a neoplastic phenotype.

Instabilotyping: comprehensive identification of frameshift mutations caused by coding region microsatellite instability

Coding region frameshift mutation caused by microsatellite instability (MSI) is one mechanism contributing to tumorigenesis in cancers with MSI in high frequency. Mutation of TGFBR2 is one example of this process. To identify additional examples, a large-scale genomic screen of coding region microsatellites was conducted. 1115 coding homopolymeric loci with six or more nucleotides were identified in an online genetic database. Mutational screening was performed at 152 of these loci in 46 colorectal tumors with MSI in high frequency. Nine loci were mutated in > or =20% of tumors, 10 loci in 10-20%, 24 loci in 5-10%, 43 loci in <5%, and 66 loci were not mutated in any tumors. The most frequently mutated novel loci were the activin type II receptor gene (58.1%), SEC63 (48.8%), AIM 2 (47.6%), a gene encoding a subunit of the NADH-ubiquinone oxidoreductase complex (27.9%), a homologue of mouse cordon-bleu (23.8%), and EBP1/PA2G4 (20.9%). This genome-wide approach identifies coding region MSI in genes or pathways not implicated previously in colorectal tumorigenesis, which may merit functional study or other additional analysis.

Adenomatous polyposis coli gene promoter hypermethylation in non-small cell lung cancer is associated with survival

Methylation of 5' CpG islands in promoter and upstream coding regions has been identified as a mechanism for transcriptional inactivation of tumor suppressor genes. The purpose of this study was to determine whether hypermethylation of the adenomatous polyposis coli (APC) gene promoter occurs in primary non-small cell lung cancer (NSCLC), and whether hypermethylated APC has any relationship with survival. APC promoter 1A methylation was determined in normal and corresponding tumor tissue from 91 NSCLC patients and in a control group of 10 patients without cancer, using a quantitative fluorogenic real-time PCR (Taqman) system. APC promoter methylation was detectable in 86 (95%) of 91 tumor samples, but also in 80 (88%) of 91 normal samples of NSCLC patients, and in only two (20%) of 10 normal lung tissues of the control group. The median level of APC promoter methylation was 4.75 in tumor compared to 1.57 in normal lung tissue (P<0.001). Patients with low methylation status showed significantly longer survival than did patients with high methylation status (P=0.041). In a multivariate analysis of prognostic factors, APC methylation was a significant independent prognostic factor (P=0.044), as were pT (P=0.050) and pN (P<0.001) classifications. This investigation shows that APC gene promoter methylation occurs in the majority of primary NSCLCs. High APC promoter methylation is significantly associated with inferior survival, showing promise as a biomarker of biologically aggressive disease in NSCLC.

p14ARF silencing by promoter hypermethylation mediates abnormal intracellular localization of MDM2

The INK4a/ARF locus encodes two distinct tumor suppressors, p16INK4a and p14ARF. Although the contribution of p16INK4a to human tumorigenesis through point mutation, deletion, and hypermethylation has been widely documented, little is known about specific p14ARF lesions and their consequences. Recent data indicate that p14ARF suffers inactivation by promoter hypermethylation in colorectal cancer cells. Because it is known that p14ARF prevents MDM2 nucleocytoplasmic shuttling and thus stabilizes p53 by attenuating MDM2-mediated degradation, we studied the relationship of p14ARF epigenetic silencing to the expression and localization of MDM2 and p53. Cancer cell lines with an unmethylated p14ARF promoter showed strong nuclear expression of MDM2, whereas in a colorectal cell line with p14ARF hypermethylation-associated inactivation, MDM2 protein was also seen in the cytosol. Treatment with the demethylating agent 5-aza-2'-deoxycytidine was able to reinternalize MDM2 to the nucleus, and p53 expression was restored. No apparent changes in retinoblastoma localization were observed. We also studied the profile of p14ARF promoter hypermethylation in an extensive collection of 559 human primary tumors of different cell types, observing that in colorectal, gastric, renal, esophageal, and endometrial neoplasms and gliomas, aberrant methylation of p14ARF was a relatively common epigenetic event. MDM2 expression patterns revealed that lack of p14ARF promoter hypermethylation was associated with tumors showing exclusive nuclear MDM2 staining, whereas MDM2 cytosolic staining was frequently observed in neoplasms with aberrant p14ARF methylation. Taken together, these data support that epigenetic silencing of p14ARF by promoter hypermethylation is a key mechanism in the disturbance of the MDM2 nuclear localization in human cancer.

Promoter methylation regulates Helicobacter pylori-stimulated cyclooxygenase-2 expression in gastric epithelial cells

Cyclooxygenase (COX)-2, the inducible form of the rate-limiting enzyme for prostaglandin synthesis, is up-regulated in gastrointestinal cancers and is a key mediator of epithelial cell growth. Helicobacter pylori is causally linked to gastric cancer. In H. pylori gastritis, COX-2 expression localizes to the subepithelial region, with variable levels in the epithelium. In contrast, in gastric cancer, COX-2 strongly predominates in the epithelium, suggesting that the transition to consistent epithelial COX-2 overexpression may be a critical molecular event in gastric carcinogenesis. Because aberrant promoter methylation inhibits expression of a variety of genes in gastrointestinal cancers, we sought to determine whether methylation of the COX-2 promoter could regulate the response to H. pylori in gastric epithelial cells. We assessed COX-2 expression and promoter methylation status in six gastric epithelial cell lines. In all four of the cell lines that exhibited basal expression of COX-2 and a significant increase in expression in response to H. pylori, the COX-2 promoter was unmethylated, whereas in the two cell lines that did not express COX-2, the COX-2 promoter was methylated. Treatment of COX-2-methylated cells with the demethylating agent 5-azacytidine had a modest effect on COX-2 expression, but when 5-azacytidine-treated cells were subsequently stimulated with H. pylori, there was a significant, 5-10-fold enhancement of both COX-2 mRNA and protein expression and release of the COX-2 product, prostaglandin E2. In contrast, in COX-2-expressing cell lines that were unmethylated at the COX-2 promoter, 5-azacytidine had no effect on H. pylori-stimulated COX-2 expression. These findings suggest that loss of COX-2 methylation may facilitate COX-2 expression and promote gastric carcinogenesis associated with H. pylori infection.

Hypermethylation of the hMLH1 gene promoter is associated with microsatellite instability in early human gastric neoplasia

A significant portion of gastric cancers exhibit defective DNA mismatch repair, manifested as microsatellite instability (MSI). High-frequency MSI (MSI-H) is associated with hypermethylation of the human mut-L homologue 1 (hMLH1) mismatch repair gene promoter and diminished hMLH1 expression in advanced gastric cancers. However, the relationship between MSI and hMLH1 hypermethylation has not been studied in early gastric neoplasms. We therefore investigated hMLH1 hypermethylation, hMLH1 expression and MSI in a group of early gastric cancers and gastric adenomas. Sixty-four early gastric neoplasms were evaluated, comprising 28 adenomas, 18 mucosal carcinomas, and 18 carcinomas with superficial submucosal invasion but clear margins. MSI was evaluated using multiplex fluorescent PCR to amplify loci D2S123, D5S346, D17S250, BAT 25 and BAT 26. Methylation-specific PCR was performed to determine the methylation status of hMLH1. In two hypermethylated MSI-H cancers, hMLH1 protein expression was also evaluated by immunohistochemistry. Six of sixty-four early gastric lesions were MSI-H, comprising 1 adenoma, 4 mucosal carcinomas, and 1 carcinoma with superficial submucosal invasion. Two lesions (one adenoma and one mucosal carcinoma) demonstrated low-frequency MSI (MSI-L). The remaining 56 neoplasms were MSI-stable (MSI-S). Six of six MSI-H, one of two MSI-L, and none of thirty MSI-S lesions showed hMLH1 hypermethylation (P<0.001). Diminished hMLH1 protein expression was demonstrated by immunohistochemistry in two of two MSI-H hypermethylated lesions. hMLH1 promoter hypermethylation is significantly associated with MSI and diminished hMLH1 expression in early gastric neoplasms. MSI and hypermethylation-associated inactivation of hMLH1 are more prevalent in early gastric cancers than in gastric adenomas. Thus, hypermethylation-associated inactivation of the hMLH1 gene can occur early in gastric carcinogenesis.

Hypermethylated APC DNA in plasma and prognosis of patients with esophageal adenocarcinoma

BACKGROUND

The adenomatous polyposis coli (APC) locus on chromosome 5q21-22 shows frequent loss of heterozygosity (LOH) in esophageal carcinomas. However, the prevalence of truncating mutations in the APC gene in esophageal carcinomas is low. Because hypermethylation of promoter regions is known to affect several other tumor suppressor genes, we investigated whether the APC promoter region is hypermethylated in esophageal cancer patients and whether this abnormality could serve as a prognostic plasma biomarker.

METHODS

We assayed DNA from tumor tissue and matched plasma from esophageal cancer patients for hypermethylation of the promoter region of the APC gene. We used the maximal chi-square statistic to identify a discriminatory cutoff value for hypermethylated APC DNA levels in plasma and used bootstrap-like simulations to determine the P: value to test for the strength of this association. This cutoff value was used to generate Kaplan-Meier survival curves. All P values were based on two-sided tests.

RESULTS

Hypermethylation of the promoter region of the APC gene occurred in abnormal esophageal tissue in 48 (92%) of 52 patients with esophageal adenocarcinoma, in 16 (50%) of 32 patients with esophageal squamous cell carcinoma, and in 17 (39.5%) of 43 patients with Barrett's metaplasia but not in matching normal esophageal tissues. Hypermethylated APC DNA was observed in the plasma of 13 (25%) of 52 adenocarcinoma patients and in two (6.3%) of 32 squamous carcinoma patients. High plasma levels of methylated APC DNA were statistically significantly associated with reduced patient survival (P =.016).

CONCLUSION

The APC promoter region was hypermethylated in tumors of the majority of patients with primary esophageal adenocarcinomas. Levels of hypermethylated APC gene DNA in the plasma may be a useful biomarker of biologically aggressive disease in esophageal adenocarcinoma patients and should be evaluated as a potential biomarker in additional tumor types.

Microsatellite instability in inflammatory bowel disease-associated neoplastic lesions is associated with hypermethylation and diminished expression of the DNA mismatch repair gene, hMLH1

Twelve to 15% of sporadic colorectal cancers display defective DNA mismatch repair (MMR), manifested as microsatellite instability (MSI). In this group of cancers, promoter hypermethylation of the MMR gene hMLH1 is strongly associated with, and believed to be the cause of, MSI. A subset of colorectal neoplastic lesions arising in inflammatory bowel disease (IBD) is also characterized by MSI. We wished to determine whether hMLH1 hypermethylation was associated with diminished hMLH1 protein expression and MSI in IBD neoplasms. We studied 148 patients with IBD neoplasms, defined as carcinoma or dysplasia occurring in patients with ulcerative colitis or Crohn's disease. MSI was evaluated using multiplex fluorescent PCR to amplify loci D2S123, BAT-25, BAT-26, D5S346, and D17S250 in all cases. Lesions were characterized as high-frequency MSI (MSI-H) if they manifested instability at two or more loci, low-frequency MSI (MSI-L) if unstable at only one locus, or MS-stable (MSS) if showing no instability at any loci. Methylation-specific PCR was performed to determine the methylation status of the hMLH1 promoter region. hMLH1 protein expression was also evaluated by immunohistochemistry. Thirteen (9%) of 148 neoplasms arising in IBD were MSI-H, comprising 11 carcinomas and 2 dysplastic lesions. Sixteen additional lesions (11%) were MSI-L, comprising 11 carcinomas and 5 dysplastic lesions. The remaining 118 neoplasms (80%) were MSS. Six (46%) of 13 MSI-H, 1 (6%) of 16 MSI-L, and 4 (15%) of 27 MSS lesions showed hMLH1 hypermethylation (P = 0.013). Diminished hMLH1 protein expression in neoplastic cell nuclei relative to surrounding normal cell nuclei was demonstrated immunohistochemically in four of four (100%) hypermethylated lesions tested. In IBD neoplasia, hMLH1 promoter hypermethylation occurs frequently in the setting of MSI, particularly MSI-H. Furthermore, hMLH1 hypermethylation and MSI are strongly associated with diminished hMLH1 protein expression in IBD neoplasms. These findings suggest that hMLH1 hypermethylation causes defective DNA MMR in at least a subset of IBD neoplasms.

Analysis of adenomatous polyposis coli promoter hypermethylation in human cancer

Germ-line mutations in the tumor suppressor gene APC are associated with hereditary familial adenomatous polyposis (FAP), and somatic mutations are common in sporadic colorectal tumors. We now report that methylation in the promoter region of this gene constitutes an alternative mechanism for gene inactivation in colon and other tumors of the gastrointestinal tract. The APC promoter is hypermethylated in 18% of primary sporadic colorectal carcinomas (n = 108) and adenoma (n = 48), and neoplasia with APC methylation fails to express the APC transcript. Methylation affects only wild-type APC in 95% of cases and is not observed in tumors from FAP patients who have germ-line APC mutations. As with APC mutation, aberrant APC methylation occurs early in colorectal carcinogenesis. When other tumor types are analyzed (n = 208), methylation of the APC promoter is not restricted to the colon but is present in tumors originating elsewhere in the gastrointestinal tract but rarely in other tumors. Our data suggest that hypermethylation of APC provides an important mechanism for impairing APC function and further underscores the importance of the APC pathway in gastrointestinal tumorigenesis.

Distinct methylation patterns of two APC gene promoters in normal and cancerous gastric epithelia

The adenomatous polyposis coli (APC) tumor suppressor gene is mutationally inactivated in both familial and sporadic forms of colorectal cancers. In addition, hypermethylation of CpG islands in the upstream portion of APC, a potential alternative mechanism of tumor suppressor gene inactivation, has been described in colorectal cancer. Because a subset of both gastric and colorectal cancers display the CpG island methylator phenotype, we hypothesized that epigenetic inactivation of APC was likely to occur in at least some gastric cancers. APC exhibits two forms of transcripts from exons 1A and 1B in the stomach. Therefore, we investigated CpG island methylation in the sequences upstream of exons 1A and 1B, i.e., promoters 1A and 1B, respectively. We evaluated DNAs from 10 gastric cancer cell lines, 40 primary gastric cancers, and 40 matching non-cancerous gastric mucosae. Methylated alleles of promoter 1A were present in 10 (100%) of 10 gastric cancer cell lines, 33 (82.5%) of 40 primary gastric cancers, and 39 (97.5%) of 40 noncancerous gastric mucosae. In contrast, promoter 1B was unmethylated in all of these same samples. APC transcripts from exon 1A were not expressed in nine of the 10 methylated gastric cancer cell lines, whereas APC transcripts were expressed from exon 1B. Thus, expression from a given promoter correlated well with its methylation status. We conclude that in contrast to the colon, methylation of promoter 1A is a normal event in the stomach; moreover, promoter 1B is protected from methylation in the stomach and thus probably does not participate in this form of epigenetic APC inactivation.

Mutation of hMSH3 and hMSH6 mismatch repair genes in genetically unstable human colorectal and gastric carcinomas

Mutations within microsatellite sequences, consisting of additions or deletions of repeat units, are known as the replication/repair error positive (RER+) phenotype or micorsatellite instability (MI). Microsatellite instability has been demonstrated in hereditary and sporadic colorectal carcinomas and is usually observed in noncoding regions of genomic DNA. However, relatively few coding region targets of MI have been identified thus far. Using PCR, we amplified regions encompassing (A)8 and (C)8 microsatellite tracts within hMSH3 and hMSH6 from 31 RER+ sporadic colorectal tumors, 8 hereditary colon cancers, 23 RER+ gastric carcinomas, and 32 RER- gastric tumors. Mutations were found in 11 (36%) of 31 sporadic colon carcinomas, 4 (50%) of 8 hereditary colorectal cancers, and 5 (22%) of 23 RER+ gastric carcinomas, but in only 2 (6%) of 32 RER- gastric carcinomas. These frameshift mutations cause premature stop codons downstream that are predicted to abolish normal protein function. Our results and those of others suggest that DNA mismatch repair genes, such as hMSH3 and hMSH6, are targets for the mutagenic activity of upstream mismatch repair gene mutations and that this enhanced genomic instability may accelerate the accumulation of mutations in RER+ tumors.