April 2000

6338

ADULT COLO·COLONIC INTUSSUSCEPTION DUE TO CO·LONIC MALT LYMPHOMA AND ITS SUCCESSFUL RESOLU­TION BY CHEMOTHERAPY WITHOUT SURGICAL INTERVEN·TlON.Prasad M. Kulkarni, Joseph L. Kinzie, Ayad AI-Katib, Wayne State Uni­versity/Detroit Med Ctr, Detroit, MI; WsuIDmc, Detroit, MI; Dmc/Wsu,Detroit, MI.

Introduction: Colo-colonic intussusceptions are uncommon varieties ofbowel intussusceptions. Intussusception of colo-colonic location as a resultof colonic MALT lymphoma has been very rarely reported. Successfulresolution of colonic intussusception in an adult with medical treatmentalone for the underlying bowel lymphoma has not been reported so far.Case report: A 63 year-old Caucasian male was diagnosed with gastric andcolonic MALT lymphoma (mild type) in 1995 and treated with 2 cycles ofchemotherapy without success. He returned in 1998 with lethargy, wors­ening pedal edema and intermittent diarrhea for four weeks. Severe mal­nutrition, oral thrush, and bilateral pitting edema were major physicalfindings. Abdominal examination revealed good bowel sounds withouthepatosplenomegaly. A CT scan of the abdomen performed as part ofstaging work-Up revealed diffuse lymphomatous involvement of the entirecolon and mesenteric lymphadenopathy. An area of intussusception wasidentified in the descending colon. Colonoscopy was performed as apotential therapeutic measure and also for obtaining biopsies. At colones­copy, the entire colon was studded with nodular lesions of various sizesthat were near-occluding the bowel lumen. Further chemotherapy withESHAP regimen (Etoposide, Solumedrol, High dose ARA-C and cis­Platinum) was administered and the patient responded well to this regimen.A follow-up CT at four months showed that the intussusception as well asthe lymphomatous involvement of the colon was gone and there has beenno recurrence for the past 18 months. Conclusion : Treatment of adultintussusception has always been thought to be surgical and neoplasticlesions almost invariably accompany. To our knowledge this is the firstreport of colo-colonic intussusception due to a colonic MALT-type lym­phoma that resolved by chemotherapy alone without any surgical interven­tion. It is important to recognize that in rare instances. medical treatment ofthe underlying malignancy alone may lead to resolution of the intussus­ception and may be a therapeut ic option in a high-risk surgical candidate.

6339

SECONDARY BILE SALTS MODULATE EXPRESSION OF TRI·OREDOXIN REDUCTASE IN RESPONSE TO OXIDATIVESTRESS IN COLONIC EPITHELIAL CELLS,Frank Kullmann, Sandra Lechner, Klaus Schlottmann, Ulf Mueller-Ladner,Christopher Benzing, Juergen Schoelmerich , Dept of Internal Medicine I,Univ of Regensburg, Regensburg, Germany.

Object ive: Bile acids have been suggested to be involved in coloniccarcinogenesis, but the molecular mechanisms remain elusive. Recently wedescribed an upregulation of the redox protein thioredoxin reductase (TR)mRNA in colon cancer cells after incubation with bile acids. TR is one ofthe key components of the redox system. Consequently , we investigatedthe question whether bile acids induce oxidative stress resulting in anactivation of TR. Methods : The human colon cancer cell line HT29 wascultured in a medium containing either 50 or 500/LM bile salts (deoxy­cholate (DC), lithocholate (LC). ursodeoxycholate (UDC)), DMSO (0.1and 1%). l2-0-tetradecanoylphorbol-J 3-acelate (TPA) (1,10 or loong/mlmedium) or Acetone (0.1%) for 3 and 6 hours. Semiquantitative RT-PCRwas performed using gene specific primers for TR. Oxidative burst activitywas determined by flow cytornetry using dihydrorhodamine 123. Results:TR-mRNA expression was not altered after 3 h incubation with 50 or500/LM DC. Extension of the incubation time to 6h revealed a clearincrease of TR-expression already after treatment with 50/LM, especiallywith 5OO/LM DC (1.9 and 2.3-fold). 6h incubation with LC resulted in noincrease of the TR·mRNA with 50/LM, but in a 3.8 fold increase with500/LM. Treatment with 50 or 500JLM UDC for 3 or 6 h did not alter theTR-mRNA expression. After incubating cells with TPA (l oong/ml) a2.25-fold increase in TR-expression was obvious, similar to the increaseafter treatment with 500/LM DC for 6 h. Oxidative burst was stimulatedwith TPA. The ratio between stimulated and unstimulated cells wasl3.5±4.75 indicating oxidative burst. Coincubation with 500/LM DC for6 h resulted in a significant (p<O.OI) increase of the ratio betweenstimulated and unstimulated cells to 35.6±8.1. UDC did not influence theratio indicating a lack of oxidative burst activity. Conclusions: Our findingsindicate that the secondary bile salts deoxycholate and lithocholate are ableto induce TR-mRNA in an extent comparable to TPA. Ursodeoxycholatedoesn't influence the TR-mRNA expression. Deoxycholate in a concen­tration of 500/LM over a 6 h incubation period induces a significantincrease of oxidative burst acitivity. It is yet unclear whether these mech­anisms are essential to protect the cells against the cytotoxic bile salts orare part of the stimulation of cell growth and tumor promoting induced bytoxic bile salts. This research was funded by the Deutsche Forschungsge­meinschaft (Ku 1024/6-1, Mu 138311-1 )

AGAA1395

6340METHYLATION PATTERN OF HMLHI AND MICROSATEL·LITE INSTABILITY IN SPORADIC COLORECTAL CANCERS.Pedro A. Lage, Marilia L. Cravo, Lara Maia, Isabel M. Claro, Paula P.Chaves. Cristina M. Albuquerque , Claudia Gaspar, Carlos A. Nobre­Leitao, IPO, Lisbon, Portugal.

Background : Microsatellite instability (MSI) is the hallmark of colorectalcancer (CRC) in HNPCC and is associated with mismatch repair genes(MMR) silencing, mainly in hMLHI and hMSH2 genes. MSI is alsopresent in about 10-15% of sporadic CRC but the genetic mechanismresponsible for its occurrence is not completel y understood . Aims: Toevaluate the presence of MSI in sporadic CRC and analyze the mechanismof MMR gene inactivation - mutation and/or promoter gene hypermethyl­ation - in cases with MSI. Patients and Methods: We included 62 patient swith sporadic CRC (mean age: 64; 35 male and 27 female ). MSI wasdetected by evaluating the length of poly(CA) or poly(A) repeats sequencesin 5 markers: D2S123, D5S346, DI7S250, BAT-25 and BAT-26. MSI wasclassified as high (MSI-H: ~40%), low (MSI-L: < 40%) or absent (MSS:0%), according to the number of positive markers. Gennline and somaticmutations in hMSH2 and hMLHI were analyzed in patients with MSIpositive tumors using DGGE and direct sequencing. Methylation of pro­moter region of hMLHl and hMSH2 genes was evaluated using a PCRbased method. Results: 7/62 (l 1%) CRC were MSI-H and 2/62 (3%) wereMSI-L . The remaining 53 tumors were microsatellite stable. In cases withMSI-H, we found two germline mutations in hMLHI (one missense inexon 16; one nonsense in exon I) and one somatic mutation in hMSH2. AllMSI-H CRCs, including those with somatic or germline mutations in MMRgenes, showed hypermethylation of the hMLHl promoter region whichwas not present in the two cases with MSI-L. Methylation of hMSH2 genewas not found in any instance. Conclusions: Microsatellite instability ofhigh grade in sporadic CRC was associated with hypermethylation of thehMLHl promoter region. Whether this abnormality in DNA methylation isprimary or secondary to the mutator phenotype remains to be established .This research was supported by Liga Portuguesa Contra 0 Cancro.

6341

GENOTYPING OF FRAMESHIFT MUTATIONS IN COLOREC­TAL CANCER (CRC) OF THE MICROSATELLITE MUTATORPHENOTYPE (MMP).Luigi Laghi, Paolo Bianchi, Ombretta Orbetegl i, Giorgia Ceva Grimaldi ,Massimo Roncalli, Alberto Malesci, Ich, Rozzano-Mi, Italy; Inst ClinicoHumanitas, Rozzano-Mi, Italy.

Background. CRC of the MMP harbor frameshift mutations at codingmononucleotide repeats of target genes. Yet, it is not known whether thenumber of these mutations is related to cancer stage and progression. Aim.To study target gene frameshift mutations in MMP CRC of different stagesand in their nodal metastases. Materials and methods. Twelve MMP CRCcoJorectal cancers (6 Dukes stage B, 5 stage C, and I stage D) andmetastatic Iymphnodes from 4 cancers were studied. TGFf3RlI, CASP-5,BAX, hMSH3. hMSH6, IGFR/l, and BRCA2 were tested for characteristicframeshifts mutations. Results. Individual genetic patterns of investigatedtumors are reported in the Figure. Shaded boxes stand for the occurrenceof a frameshift mutation. The ratio of mutated target genes to the totalnumber of tested genes, was 0.5 in 6 non-metastatic tumors and 0.33 in 6metastatic cancers. No mutations other than those seen in the correspond­ing primaries were observed in metastatic nodes. Conclusions. The lack ofcorrelation between tumor stage and number of mutated genes as well asthe absence of additional mutations in metastatic nodes, indicate thatdamage accumulation in known target genes is not a determinant of tumorprogression in MMP CRC.

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