Mutation of the MENIN gene in sporadic pancreatic endocrine tumors

Pancreatic endocrine tumors occur both sporadically and as part of the multiple endocrine neoplasia type 1 (MEN1) syndrome. MEN1 is an autosomal dominant disease characterized by parathyroid hyperplasia, pancreatic endocrine tumors, and pituitary adenomas. The MEN1 gene called MENIN maps to chromosome 11q13 and is thought to function as a tumor suppressor gene. We previously demonstrated loss of heterozygosity (LOH) at 11q13 in approximately 40% of sporadic pancreatic endocrine tumors and hypothesize that MENIN is involved in the development of these tumors. Thirty-one sporadic pancreatic endocrine tumors were analyzed for mutation of MENIN by nonradioactive single-stranded conformation polymorphism. Twelve mutations were detected in 31 sporadic pancreatic endocrine tumors (34%). Twelve of these 31 tumors previously demonstrated loss of heterozygosity at 11q13. Of the tumors with LOH, seven contained mutations of the MENIN gene (58%). The majority of the MENIN mutations occurred within exon 2. Two independent mutations in MENIN were detected in a gastrinoma that also revealed LOH, leading to the possibility of another tumor suppressor gene locus at 11q13. Mutations were present in both benign and malignant pancreatic endocrine tumors, suggesting that a MENIN gene mutation is a frequent and early event in the tumorigenesis. The high incidence of truncating mutations in tumors with LOH at 11q13 support the hypothesis that MENIN is a tumor suppressor gene.

Current concepts in the surgical management of multiple endocrine neoplasia type 1 pancreatic-duodenal disease. Results in the treatment of 40 patients with Zollinger-Ellison syndrome, hypoglycaemia or both

The management of multiple endocrine neoplasia type 1 (MEN-1) pancreatic-duodenal disease, particularly when the Zollinger-Ellison syndrome (ZES) is the presenting manifestation, has remained controversial. The management of hypoglycaemia and other syndromes as well as large tumours detected by imaging is less controversial, although standardized surgical techniques have not been generally adapted. The rationale for an aggressive operative management plan for ZES and other syndromes is based on the facts that neuroendocrine tumours of both the pancreas and the duodenum have malignant potential and that the functional manifestations can be controlled with appropriate surgical procedures based on current concepts of the MEN-1 disease. Of the ten concepts presented, the one critical to the surgical treatment of ZES is that a duodenotomy is essential in detecting the source of hypergastrinaemia in most MEN-1 patients. The complete operation is multifaceted and includes peripancreatic lymph node dissection (ZES), enucleation of any head or uncinate tumours and a distal pancreatectomy. Our results in 40 MEN-1 patients with functional syndromes treated with these procedures are encouraging. Ten patients with hypoglycaemia (four with concomitant ZES) have been 'cured' with follow-up as long as 18 years. Sixty-eight per cent of 34 patients with ZES have remained eugastrinaemic during follow-up as long as 19 years. One patient developed a solitary liver metastasis that was excised a year ago without other evidence of recurrence. There has been no operative mortality and three subsequent deaths were due to unrelated disease.

Genetic alterations in gastrinomas and nonfunctioning pancreatic neuroendocrine tumors: an analysis of p16/MTS1 tumor suppressor gene inactivation

Neoplasms of the endocrine pancreas are extremely rare, and molecular mechanisms influencing their development are poorly understood. Nevertheless, gastrinomas have become a paradigm for the study of hormonally active tumors. In the present study, 12 gastrinoma and nonfunctioning pancreatic neuroendocrine tumor specimens were evaluated for genetic alterations of the p16/MTS1 tumor suppressor gene. DNA extracted from microdissected portions of paraffin-embedded tumor sections were examined for mutations and homozygous deletions using "Cold" single-strand conformation polymorphism and semiquantitative PCR-based analyses, respectively. Samples were also analyzed for the presence of 5' CpG island hypermethylation using methylation-specific PCR. The p16/MTS1 gene was found to be homozygously deleted in 41.7% of tumors and methylated in 58.3%, but no mutations were identified by single-strand conformation polymorphism analyses. Overall, 91.7% of the specimens demonstrated inactivating alterations in p16/MTS1. These data suggest that transcriptional silencing of p16/MTS1 is a frequent event in these rare and poorly understood tumors.

Somatic mutations of the MEN1 tumor suppressor gene in sporadic gastrinomas and insulinomas

Gastrinomas and insulinomas are frequent in multiple endocrine neoplasia type 1 (MEN1). The MEN1 tumor suppressor gene was recently identified. To elucidate the etiological role of the MEN1 gene in sporadic enteropancreatic endocrine tumorigenesis, we analyzed tumors (28 gastrinomas and 12 insulinomas) from 40 patients for MEN1 gene mutations and allelic deletions. One copy of the MEN1 gene was found to be deleted in 25 of 27 (93%) sporadic gastrinomas and in 6 of 12 (50%) sporadic insulinomas. MEN1 gene mutations were identified in 9 of 27 (33%) sporadic gastrinomas and 2 of 12 (17%) insulinomas and were not seen in corresponding germ-line DNA sequence. A specific MEN1 mutation was detected in one gastrinoma and in the corresponding germ-line DNA of a patient who had no family history of MEN1. Somatic MEN1 gene mutations and deletions play a critical role in the tumorigenesis of sporadic gastrinomas and may also contribute to the development of a subgroup of insulinomas.

Analysis of the retinoblastoma tumour suppressor gene in pancreatic endocrine tumours

OBJECTIVES

The molecular pathogenesis of human pancreatic endocrine tumours (PETs) is largely unknown. One attractive candidate gene for involvement in pancreatic endocrine neoplasia is the retinoblastoma (Rb) tumour suppressor gene. A deletion of the Rb gene was recently described in a human insulinoma. In addition, mice harbouring a null mutation in the Rb gene bred with p53 mutant mice develop pancreatic endocrine tumours. Therefore, we sought to determine the role that allelic loss of Rb may play in a large series of human pancreatic endocrine tumours.

PATIENTS AND MEASUREMENTS

46 pancreatic endocrine tumours were obtained from 41 patients. Utilizing genomic DNA isolated from the tumour samples and control normal cells, 2 highly polymorphic microsatellite loci (D13S153 and Rb 1.20) located within the Rb gene were PCR amplified and examined for loss of heterozygosity.

RESULTS

2 patients were homozygous at both loci and thus uninformative. The remaining 39 had informative markers at one or both of these loci, and none of the tumours from these patients demonstrated allelic loss of Rb.

CONCLUSIONS

In tumours in which Rb inactivation is pathogenetically important, somatic loss of one Rb allele commonly accompanies a point mutation or microdeletion within the other allele. Thus, the absence of demonstrable allelic loss in this large series strongly suggests that Rb gene inactivation is not frequently involved in the pathogenesis of human pancreatic endocrine tumours.

Aggressive forms of gastric neuroendocrine tumors in multiple endocrine neoplasia type I

In recent classifications of gastric endocrine tumors, tumors arising in patients with multiple endocrine neoplasia type 1 (MEN-1) are regarded to be regulated by the concomitant hypergastrinemia resulting from to pancreatic or, most commonly, duodenal gastrinomas and to have a benign behavior. In this article, we report on two cases of MEN-1 gastric neuroendocrine tumors having a fatal course. Case 1 was a young male with hyperparathyroidism and Zollinger-Ellison syndrome and with florid development of multiple gastric carcinoids and multiple duodenal gastrinomas. Metastases occurred in the liver, of exclusive gastric origin, in periduodenal lymph nodes, of exclusive duodenal origin, and in perigastric lymph nodes, of mixed origin. The patient died 48 months after diagnosis. Case 2 was an adult female patient with hyperparathyroidism, adrenocortical disorders, and gastric tumors but no hypergastrinemia. The patient died 3 months after tumor diagnosis. At autopsy, the stomach showed multiple benign carcinoids and two independent neuroendocrine carcinomas not reported before in MEN-1 and massively metastatizing to lymph nodes, liver, and peritoneum. Multiple islet cell tumors mostly producing pancreatic polypeptide were found, whereas gastrinomas were seen in neither the pancreas nor the duodenum. Allelic losses at the MEN-1 gene locus in chromosome 11q13, the mechanism responsible for tumor development in MEN-1 syndrome, were demonstrated in the carcinoid tumors of case 1 and in the neuroendocrine carcinoma of case 2. We conclude that gastric neuroendocrine tumors in patients with MEN-1 may have a poor outcome, they have the same genetic mechanism as MEN-1 tumors in other organs, and they may be independent of the trophic effect of hypergastrinemia.

Somatostatin receptor subtype gene expression in human endocrine gastroentero-pancreatic tumours

Somatostatin and its analogues are now of current use in the management of endocrine gastroentero-pancreatic (GEP) tumours for the purpose of inhibiting hormone hypersecretion, carrying scintigraphy imaging and attempting to slow down tumour growth. Recent molecular studies have revealed the existence of up to five membrane somatostatin receptor subtypes termed SSTR1-5. However, whether or not scintigraphy imaging and tumour characteristics are correlated with specific subtype(s) remains unclear. SSTR1-5 messenger RNA (mRNA) transcripts were investigated in 38 endocrine GEP tumours (32 islet cell tumours, six carcinoid) using reverse transcriptase polymerase chain reaction (RT-PCR), and their distribution was analysed with respect to tumour characteristics and scintigraphy imaging. SSTR2, SSTR5 and SSTR4 were detected in most cases of endocrine GEP tumours (92%, 84%, and 82% respectively), but SSTR1 and SSTR3 were less frequently observed (66% and 50% respectively). No clear-cut correlation was found between tumour characteristics and subtype mRNA distribution. Moreover, no differences in mRNA subtype distribution were found between the 17 tumours detected by scintigraphy and the four tumours not detected by this method. Somatostatin receptor mRNA subtypes are widely expressed in endocrine GEP tumours, but their distribution is not correlated with tumour characteristics or scintigraphy positivity.

Pancreatic endocrine tumors with loss of heterozygosity at the multiple endocrine neoplasia type I locus

BACKGROUND

Loss of heterozygosity (LOH) at chromosome 11q13 has been demonstrated in multiple endocrine neoplasia type I (MEN I) and sporadic parathyroid tumors, pituitary adenomas, and a few types of pancreatic endocrine tumors. Gastrinomas are the most common pancreatic endocrine tumor in MEN I. We hypothesized that all pancreatic endocrine tumors have LOH at 11q13, resulting in inactivation of the previously described tumor suppressor gene in this region.

METHODS

We analyzed a sporadic gastrinoma, a MEN I-associated gastrinoma, and a nonfunctional pancreatic endocrine tumor from a patient with Von Hippel-Lindau (VHL) disease for LOH at seven loci at 11q13: D11S149, PYGM, D11S427, D11S546, SEA, D11S97, and D11S146.

RESULTS AND CONCLUSIONS

We found LOH at 11q13 in all three tumors. The MEN I-associated gastrinoma we analyzed is the first tumor of this type to have LOH. This is also the first report of LOH at 11q13 in a pancreatic endocrine tumor from a patient with VHL. These findings suggest that the etiology of pancreatic endocrine tumor formation involves a common genetic pathway for sporadic, MEN I, and VHL tumors.

Allelic deletions on chromosome 11q13 in multiple endocrine neoplasia type 1-associated and sporadic gastrinomas and pancreatic endocrine tumors

Endocrine tumors (ETs) of pancreas and duodenum occur sporadically and as a part of multiple endocrine neoplasia type 1 (MEN1). The MEN1 tumor suppressor gene has been localized to chromosome 11q13 by linkage analysis but has not yet isolated. Previous allelic deletion studies in enteropancreatic ETs suggested MEN1 gene involvement in tumorigenesis of familial pancreatic ETs (nongastrinomas) and sporadic gastrinomas. However, only a few MEN1-associated duodenal gastrinomas and sporadic pancreatic nongastrinomas have been investigated. We used tissue microdissection to analyze 95 archival pancreatic and duodenal ETs and metastases from 50 patients for loss of heterozygosity (LOH) on 11q13 with 10 polymorphic markers spanning the area of the putative MEN1 gene. Chromosome 11q13 LOH was detected in 23 of 27 (85%) MEN1-associated pancreatic ETs (nongastrinomas), 14 of 34 (41%) MEN1-associated gastrinomas, 3 of 16 (19%) sporadic insulinomas, and 8 of 18 (44%) sporadic gastrinomas. Analysis of LOH on 11q13 showed different deletion patterns in ETs from different MEN1 patients and in multiple tumors from individual MEN1 patients. The present results suggest that the MEN1 gene plays a role in all four tumor types. The lower rate of 11q13 LOH in MEN1-associated and sporadic gastrinomas and sporadic insulinomas as compared to MEN1 nongastrinomas may reflect alternative genetic pathways for the development of these tumors or mechanisms of the MEN1 gene inactivation that do not involve large deletions. The isolation of the MEN1 gene is necessary to further define its role in pathogenesis of pancreatic and duodenal ETs.

Genetic mapping studies of 40 loci and 23 cosmids in chromosome 11p13-11q13, and exclusion of mu-calpain as the multiple endocrine neoplasia type 1 gene

Forty loci (16 polymorphic and 24 non-polymorphic) together with 23 cosmids isolated from a chromosome 11-specific library were used to construct a detailed genetic map of 11p13-11q13. The map was constructed by using a panel of 13 somatic cell hybrids that sub-divided this region into 19 intervals, a meiotic mapping panel of 33 multiple endocrine neoplasia type 1 (MEN1) families (134 affected and 269 unaffected members) and a mitotic mapping panel that was used to identify loss of heterozygosity in 38 MEN1-associated tumours. The results defined the most likely order of the 16 loci as being: 11pter-D11S871-(D11S288, D11S149)-11cen-CNTF-PGA-ROM1-D11S480-PYGM- SEA-D11S913-D11S970-D11S97- D11S146-INT2-D11S971-D11S533-11qter. The meiotic mapping studies indicated that the most likely location of the MEN1 gene was in the interval flanked by PYGM and D11S97, and the results of mitotic mapping suggested a possible location of the MEN1 gene telomeric to SEA. Mapping studies of the gene encoding mu-calpain (CAPN1) located CAPN1 to 11q13 and in the vicinity of the MEN1 locus. However, mutational analysis studies did not detect any germ-line CAPN1 DNA sequence abnormalities in 47 unrelated MEN1 patients and the results therefore exclude CAPN1 as the MEN1 gene. The detailed genetic map that has been constructed of the 11p13-11q13 region should facilitate the construction of a physical map and the identification of candidate genes for disease loci mapped to this region.

Endocrine tumors of the gastrointestinal tract

Endocrine tumors of the gastrointestinal tract produce a variety of secretory products that cause unique clinical syndromes. Diagnosis, which is often delayed, requires a strong index of suspicion and must be confirmed by biochemical tests. Precisely where these tumors originate remains a topic of controversy. However, several growth factors that may be involved in tumor development have been identified, and genetic abnormalities in patients with multiple endocrine neoplasia have been described. New pre- and intraoperative localization techniques have greatly increased the ability to identify and resect these tumors. The long-acting somatostatin analogue octreotide is frequently useful as a tracer to localize tumors and as symptomatic therapy for limiting release of secretory products produced by the tumors. In some instances it may also have direct anti-tumor activity.

Gastrinomas demonstrate amplification of the HER-2/neu proto-oncogene

OBJECTIVE

This study determined whether genomic amplification of HER-2/neu or mutations of the p53 and ras genes were present in gastrinomas.

SUMMARY BACKGROUND DATA

Amplification of HER-2/neu, a proto-oncogene related to the epidermal growth factor receptor, and mutation of the ras proto-oncogene and p53 tumor suppressor gene appear to play a role in the pathogenesis of some human cancers. Little is known about possible molecular alterations in gastrinomas, tumors that may be particularly virulent because of gastrin overproduction, resulting in the severe ulcer diathesis, the Zollinger-Ellison syndrome.

METHODS

The differential polymerase chain reaction (PCR) procedure was used to detect amplification of the HER-2/neu gene in DNA samples from the novel human gastrinoma cell line (PT) and from paraffin-embedded samples of gastrinomas. Sequencing techniques were used to determine whether mutations of the p53 or ras (Ha-ras, N-ras, Ki-ras) genes were present.

RESULTS

Amplification (> twofold) occurred in all gastrinoma tumor samples. Compared with normal pancreas or ileum, a 4- to 12-fold amplification of HER-2/neu was found in 3 gastrinomas, 3 to 3.3-fold in four samples and 2.1- to 2.4-fold in the remaining five tumors. A heterozygous point mutation in the p53 gene (codon 273) was found in a single sample; none of the gastrinomas contained a mutation of the ras genes.

CONCLUSIONS

Amplification of the HER-2/neu gene, but not alterations of either p53 or ras, may be involved in the pathogenesis of gastrinomas. The unique PT cell line will be a useful model to further elucidate the molecular mechanisms that contribute to gastrinoma formation and growth.

Putative tumor-suppressor gene on chromosome 11 is important in sporadic endocrine tumor formation

Endocrine tumors arising sporadically or as a manifestation of the multiple endocrine neoplasia type I syndrome (MEN I) have been shown to have mutations on chromosome 11. These mutations can be detected at the molecular level by loss of heterozygosity (LOH) for DNA markers from chromosome 11. This study represents one of the largest collections of sporadic endocrine tumors in which LOH was systematically assessed on chromosome 11 for the loci flanking the proposed MEN I region. DNA was isolated from 39 endocrine tumors and probed with 7 DNA probes spanning the region of chromosome 11q13 from the loci PYGM to INT-2. Eleven tumors demonstrated LOH at any two loci in this region. The remaining 28 tumors showed no LOH or were noninformative at these loci. Thus, nearly 30% of these tumors showed LOH in the region (from PYGM to INT-2) that is thought to contain the MEN I gene(s). Previous studies of sporadic endocrine tumors have suggested that these tumors may arise via the same mechanism as tumors of the MEN I syndrome. Namely, these sporadic tumors are thought to result from mutations leading to genetic loss on the long arm of chromosome 11, thereby inactivating a possible tumor-suppressor gene (or genes). These findings strongly support the hypothesis that sporadic pancreatic endocrine tumors share a similar etiology of tumorigenesis with tumors of the MEN I syndrome, which principally involves deletion of a tumor-suppressor element (or elements).

Flow cytometry and Zollinger-Ellison syndrome: relationship to clinical course

BACKGROUND

With successful means of controlling gastric acid secretion in patients with Zollinger-Ellison syndrome, the gastrinoma itself is becoming the major determinant of long-term survival. No methods have yet been described to predict which tumors will have more malignant courses thereby indicating which patients should undergo aggressive surgery or antitumor therapy. Because DNA analysis, using flow cytometry, has proved helpful in this regard in other tumors, the current study was designed to evaluate its utility in gastrinoma patients.

METHODS

Flow cytometry was performed on 81 paraffin-embedded gastrinoma specimens from 59 patients. Results were compared with preoperative patient characteristics, findings at surgery, and postoperative follow up.

RESULTS

Tumors were diploid in 54% of patients, near diploid in 15%, pure tetraploid in 0%, nontetraploid aneuploid in 25%, and multiple stem line aneuploid in 5%. All patients with multiple stem line aneuploid tumors had wide-spread metastases whereas all patients with nontetraploid aneuploid tumors had localized or regional disease. Median S phase percentage was 3.6. S phase percentages were higher in patients with widespread metastatic disease than in patients with localized or regional disease. Disease extent also correlated closely with fasting serum gastrin level. After removing this variable with logistic regression analysis, the significant correlation between disease extent and DNA analysis persisted.

CONCLUSIONS

DNA analysis of gastrinoma tissue specimens correlates independently with the extent of disease and may be useful in planning therapeutic strategies for patients with Zollinger-Ellison syndrome.

Chromosomal aberrations in two sporadic gastrinomas

Results of cell culture and cytogenetic analysis (standard and fluorescent in situ hybridization, FISH) of two sporadic gastrinomas are reported. Maintenance of hormonal activity was assessed by detection of gastrin levels during the first 3 months in culture. Case 1 showed clonal aberrations consisting of two marker chromosomes: marker 1 is a large metacentric chromosome and marker 2 is a small acrocentric chromosome. Case 2 showed a constitutional polymorphism with chromosome 15p+ and a clone in the tumor cell culture with trisomy for chromosome 3. To our knowledge, this is the first cytogenetic report of sporadic gastrinomas (Zollinger-Ellison syndrome).

Initiation of gastrin expression during the development of the mouse pancreas

Gastrin expression occurs in the pancreas in only two situations: (1) in cases of gastrinoma and (2) in the embryonic/fetal pancreas. The initiation of gastrin expression in the embryonic pancreas may be recapitulated during gastrinoma tumorigenesis. For this reason, we have tried to identify the point of onset of gastrin expression in the developing pancreas. Previously, determining the point of onset for genes in embryonic tissues has been difficult because of low expression levels and small tissue samples. Using the sensitive polymerase chain reaction assay, we were able to determine, with a sensitivity of 10 molecules of mRNA, the earliest expression of gastrin in the developing pancreas. This expression occurred at 30 somites, or at a gestation of 9.5 to 10 days.

Abnormal facilitative glucose transporter gene expression in human islet cell tumors

Our previous studies have shown that increased expression of GLUT1/erythrocyte and GLUT3/brain type glucose transporter genes in human tumors is associated with cellular transformation. We have now determined the levels of messenger RNAs (mRNAs) encoding these two glucose transporter isoforms as well as that of GLUT2/liver isoform in insulin-, glucagon-, and gastrin-secreting islet cell tumors. Northern blot analysis and reverse transcriptase-polymerase chain reaction revealed the presence of GLUT1 and GLUT3 mRNA in all human islet cell tumors and normal islets examined. In contrast, GLUT2 mRNA, which is present at high levels in normal islets, was not detected in insulinomas or other types of islet cell tumors. These results imply that GLUT1 and GLUT3 are primarily responsible for glucose uptake by these tumors.

Analysis of gastrinomas by immunohistochemistry and in situ hybridization histochemistry

Gastrinomas from 25 patients were examined by immunohistochemistry (IHC) and in situ hybridization histochemistry (ISH). Most patients (84%) presented with the Zollinger-Ellison syndrome. Six had multiple endocrine neoplasia type I (MEN-I). Twelve patients (48%) had duodenal primaries and 11 of 12 of these had metastases to regional lymph nodes and/or liver in spite of the small sizes of the primary tumors (mean size of 0.9 cm). Five patients had pancreatic gastrinomas and eight patients had metastatic tumor in regional lymph nodes or liver at surgery but a primary was not found. IHC and ISH analyses showed that all cases were positive for gastrin protein and 24 of 25 (96%) expressed gastrin mRNA that was easily detected in formalin-fixed, paraffin-embedded tissue sections. Both benign and malignant tumors expressed alpha subunit of human chorionic gonadotropin protein (alpha-HCG). However, only malignant gastrinomas (29%) expressed adrenocorticotropic hormone protein or proopiomelanocortin (POMC) mRNA. ISH and Northern hybridization analysis revealed that chromogranin A mRNA was the most common member of the chromogranin/secretogranin (Cg/Sg) family which was expressed in both benign and malignant gastrinomas. These results indicate that duodenal gastrinomas are common in both sporadic and MEN-1-associated cases, and small duodenal primaries may be associated with extensive regional lymph node and liver metastases. Expression of ACTH/POMC protein and mRNA was consistently associated only with malignant gastrinomas while gastrin protein, gastrin mRNA and Cgs/Sgs mRNAs were readily detected in both benign and malignant gastrinomas.

Detection of gastrin and its messenger RNA in Zollinger-Ellison tumors by non-radioactive in situ hybridization and immunocytochemistry

Gastrin immunocytochemistry and non-radioactive in situ hybridization, using biotinylated oligonucleotide probes, for gastrin mRNA have been used for studying a retrospective material of six gastrin-producing (Zollinger-Ellison) tumors. Hybridization results for gastrin mRNA were positive in all six, while gastrin immunoreactivity could be detected in five tumors. In one of the patients, different areas of the same tumor displayed differences in immunoreactivity to gastrin, but were uniformly hybridization positive. Weak hybridization signals were detected in liver metastases from a necropsy case, while the gastrin immunostaining was more pronounced. The results show that non-radioactive hybridization methods are applicable to routine clinical specimens stored for as long as 16 years and that in situ hybridization may be a useful complement to immunocytochemical diagnosis, particularly in cases where high synthesis and little storage of hormonal products occur.

Gastrinoma in multiple endocrine neoplasia type 1

Extensive experience from patients with gastrinoma as part of the multiple endocrine neoplasia type 1 (MEN 1) syndrome has revealed that MEN 1-gastrinoma patients show important differences from patients with sporadic gastrinoma. These differences comprise clinical, pathological and biochemical features, but are especially pertinent to the therapeutic approach. Therefore, the diagnosis of the MEN 1 syndrome is of great clinical importance to the gastrinoma patient and his family.

DNA ploidy in pancreatic neuroendocrine tumors

The nuclear DNA content of 17 pancreatic neuroendocrine tumors was measured from paraffin-embedded tissue with flow cytometry. The tumors were classified by immunostaining with antisera for synaptophysin, insulin, gastrin, glucagon, pancreatic polypeptide, somatostatin, and vasoactive intestinal polypeptide. Eight (47%) of the 17 tumors were aneuploid, and two (12%) were multiploid (had two aneuploid stemlines of cells). Seven of the eight insulinomas, one of the four gastrinomas, and two of the four nonspecified neuroendocrine tumors had an abnormal nuclear DNA content. The DNA indices of the aneuploid and multiploid cases ranged from 1.13 to 1.93, and three cases had a DNA index greater than 1.50. During the follow-up for up to 16 years (mean, 7 years), one patient with diploid nonspecified tumor died of the disease, another patient with a multiploid gastrinoma had metastatic disease develop, and a third patient with a multiploid nonspecified tumor was alive with the disease. The authors conclude that many neuroendocrine tumors of the pancreas have an abnormal nuclear DNA content as measured by DNA flow cytometry. DNA multiploid pancreatic neuroendocrine tumors may be associated with a less favorable clinical course, but this needs to be confirmed in additional studies.