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Florence Le Pessot

Publications and source records attributed to Florence Le Pessot.

10 recordsLinked to original sources
PubMed2006

Contribution of the BOP1 gene, located on 8q24, to colorectal tumorigenesis.

The most common form of genomic instability observed in colorectal cancer is chromosomal instability (CIN), whose molecular bases remain to be determined. We have previously demonstrated that inactivation in human cells of several components of the Pes1-Bop1 complex (BOP1, GRWD1, PES1, ORC6L, and RPL3), involved in ribosome biogenesis, altered chromosome segregation. To determine the contribution to colorectal tumorigenesis of somatic alterations of genes involved in ribosome biogenesis, we screened 56 primary colorectal cancers, using quantitative multiplex PCR of short fluorescent fragments, a sensitive method for the detection of gene dosage alterations. We found that dosage increase of the BOP1 gene was a frequent event, being detected in 39% of the tumors, and we show that it is associated with an increase of BOP1 mRNA. Scanning of 8q24, on which BOP1 is located, revealed that in colorectal cancers, gene dosage increase of BOP1 can be independent from that of MYC and was more frequent than that affecting MYC. Finally, transient overexpression of BOP1 in human cells increased the percentage of multipolar spindles. Together with our previous results, the present study strongly suggests that deregulation of the BOP1 pathway contributes to colorectal tumorigenesis.

Chromosomes, Human, Pair 8↗
PubMed2004

[Cytokeratins 7 and 20 immunohistochemistry in ampullary carcinomas].

UNLABELLED: Ampullary carcinomas (AC) account for 33% of all surgically operable pancreatoduodenal tumors. The 5-year relative survival rate is 50% and tumoral stage is the main prognostic factor. However, among the three AC histological subtypes (intestinal, pancreatobiliary and mixed), a favorable prognostic has been reported for the intestinal subtype. BACKGROUND: The aims of this study were to determine the prognostic impact of AC histologic subtype and of cytokeratins (CK) 7 and 20 immunostaining profile in these tumors. PATIENTS AND METHODS: Clinical data of 54 AC were obtained retrospectively. Macroscopic and histologic documents were reviewed and immunostainings for CK7 and CK20 were performed. RESULTS: The classification of tumors, according to histological subtype, was: intestinal 26%, pancreatobiliary 65% and mixed 9%. No correlation was found between histological subtype and tumor stage. The 5-year survival rate varied from 100% for intestinal subtype to 35% for pancreatobiliary subtype. A strong correlation (p < 0.0001) was found between histological subtype and CK7/CK20 immunostaining profile. The 5-year survival rate varied from 100% for CK7-/CK20 + AC to 40% for CK7 + /CK20- AC. CONCLUSION: In our study, the intestinal histological subtype had a favorable prognostic value. CK7/CK20 immunostaining profile was helpful for the identification of histological subtype and appears to provide additional prognostic information.

Adenocarcinoma↗
PubMed2003

PAS inclusions, immunoreactive tenascin and proliferative activity in low-grade chondrosarcomas.

To distinguish between chondrosarcoma (grade 1--borderline histology) and enchondroma, we examined six chondrosarcomas (grade 1--borderline histology) which looked like benign lesions. Their diagnosis, albeit based on clinical, radiologic and pathologic examinations, was not easily reached. Moreover, we examined six enchondromas and 11 chondrosarcomas, the diagnoses of which were straightforward. All cartilaginous tumors were studied, placing emphasis on PAS-positive intracytoplasmic globules. Anti-Ki67 proliferation-associated nuclear antigen antibody and tenascin antibody were applied. The following features were observed in low-grade chondrosarcomas: (1) masses of hyalin and/or myxoid cartilage invading spaces around the tumor, (2) host lamellar bone trabeculae surrounded by cartilage on all sides, (3) tumoral resorption of bone trabeculae. Intracytopasmic hyalin globules (ICG) were more frequently found in malignant than in benign neoplasm (p = 0.042). Moreover, tenascin matrix immunoreactivity was more likely to be observed in benign than in malignant neoplasm (p = 0.029). Ki67 immunoreactivity was more frequent in characterized than in low-grade chondrosarcomas or in enchondromas, where it was null (p = 0.0044).

Adolescent↗
PubMed2003

[Retrorectal cystic hamartomas. Report of one case].

Retrorectal cystic hamartomas (RCH) are rare congenital lesions of the presacral space, of which 68 cases are reported under different terms. Clinicopathologic features are usually constant and similar to the present case. A 23-year-old woman complained of abdominal and perineal pains for several months. Physical examination revealed a nodular mass in the posterior part of the rectum. A pelvic MRI showed a 5.5 cm cystic retrorectal mass compressing the rectum. The patient underwent surgical resection. Pathologic examination found an ill-defined nodular mass, composed by numerous cysts surrounded by fibroadipose tissue. Cysts were lined by different epithelia: keratinized and non keratinized squamous, transitional, ciliated and mucus-producing columnar epithelia. Few mucinous glands were noted, connected to some cysts. These epithelial structures were surrounded by connective tissue in which well-differentiated bundles of smooth muscle fibers were present without well-formed muscularis. The RCH differential diagnosis includes principally congenital cysts: epidermal cysts, cystic teratomas, dermoid cysts, anal gland cysts and rectal duplications. An embryologic origin of RCH from remnants of the postanal gut is currently accepted. Loco-regional inflammatory process frequently complicates this lesion and can cause perirectal fistulae. RCH also possesses a malignancy potential, with development of adenocarcinomas. To avoid these complications, complete excision is recommended.

Abdominal Pain↗
PubMed2003

[Recurring bone epithelioid hemangioma].

Bone vascular tumors are very rare. Epithelioid types are described according to their architecture, their degree of vascular differentiation, and their cytonuclear atypia. The include epithelioid hemangioma, epithelioid hemangioendothelioma, and angiosarcoma. We report a case of L4 corpus vertebral bone epithelioid hemangioma. The patient was a 25-year-old man with a tumor that recurred twice. The lesion was characterized by a vascular lumen lined by cells with regular nuclei and inflammatory infiltrates. Capillaries were lined by prominent epithelioid endothelial cells, associated with CD31+ and cytokeratin-.

Adult↗
PubMed2002

Overexpression of B-type cyclins alters chromosomal segregation.

To identify genes which overexpression results into chromosomal instability (CIN), we developed a biological approach based on a yeast indicator strain in which CIN can be detected by a sectoring phenotype. Screening in this strain of a yeast genomic library cloned into a high copy vector led us to identify, among the clones generating 100% of sectoring colonies, Clb5, one of the six B-type cyclins present in yeast. Overexpression of cyclin B2 and cyclin B1, the two human homologs of Clb5, in the CIN indicator strain resulted also into a sectoring phenotype and induced, like overexpression of Clb5, an abnormal sensitivity to benomyl, indicating that overexpression of B-type cyclins alters the spindle checkpoint. In a series of 38 primary colorectal cancers, we detected in five tumors (13%) an accumulation of cyclin B1, which was neither related to mRNA overexpression nor to mutation within the coding region, and in five other tumors (13%) a 2-10-fold increase of cyclin B2 mRNA which was not related to gene amplification. These results suggest that overexpression of cyclins B, resulting from different mechanisms, could contribute, through an alteration of the spindle checkpoint, to the chromosomal instability observed in cancer.

Amino Acid Sequence↗
PubMed2002

Acute enteral glutamine infusion enhances heme oxygenase-1 expression in human duodenal mucosa.

The heat shock protein, heme oxygenase-1 (HO-1), contributes to the protection of the intestine. Some experimental models suggest that induction of HO-1 by glutamine may contribute to the preservation of intestinal mucosa. The effect of an enteral infusion of glutamine for 6 h on HO-1 expression in duodenal mucosa was studied in healthy men and women and compared with an isonitrogenous mixture of amino acids. After enteral infusion, endoscopic duodenal biopsies were performed and either fixed in formalin for immunohistochemistry or frozen for HO-1 mRNA analysis by reverse transcriptase-polymerase chain reaction. Histologic examination revealed that HO-1 was constitutively expressed in intestinal epithelial cells (IEC), and that glutamine increased the grade of HO-1 immunostaining (P </= 0.01). Glutamine also increased the percentage of HO-1 immunoreactive lamina propria cells (LPC, 10.5 vs. 7.5%, P </= 0.05). Glutamine significantly increased HO-1 mRNA expression compared with control amino acids: median (range) 156 (102-182) vs. 100 (68-179)%, P </= 0.05. The mRNA level for HO-1 was correlated with the percentage of immunoreactive LPC (r = 0.55, P = 0.017) and the grade of immunostaining in IEC (r = 0.51, P = 0.030). In conclusion, glutamine enhanced HO-1 mRNA and protein expression in human duodenal mucosa. These data support further evaluation of the effects of glutamine on intestinal HO-1 during states of intestinal inflammation.

Adult↗
PubMed2002

[Detection of HHV8 latent nuclear antigen by immunohistochemistry. A new tool for differentiating Kaposi's sarcoma from its mimics].

UNLABELLED: The purpose of this work was to study the value of HHV8 latent nuclear antigen 1 detection by immunohistochemistry in Kaposi sarcoma and its mimics. MATERIALS AND METHODS: : We used the mAB LNA53 against the latent nuclear antigen 1 of HHV8 to study its expression by immunohistochemistry in paraffin embedded biopsy of Kaposi and its mimics. We also performed in vitro PCR for HHV8 DNA, extracted from the same paraffin embedded biopsies. We studied characteristic lesions of 26 Kaposi sarcoma; 20 cutaneous lesions raising problems of differential diagnosis. We also studied 11 biopsies of skin, mucosa, or lymph nodes of patients infected by HHV8 but without Kaposi sarcoma, and 22 lesions initially classified by histological analysis as uncertain Kaposi sarcoma . RESULTS: : In all cases of Kaposi, HHV8 was detected in the majority of tumor cells, with no expression in other adjacent cells. In these biopsies HHV8 DNA, was identified by in vitro PCR. None of the 20 Kaposi sarcoma mimics and the 11 lesions of patients infected by HHV8 but without any Kaposi sarcoma, were HHV8+ on immunohistochemistry sections or by PCR. From the 22 cases of uncertain Kaposi sarcoma, only the 14 lesions HHV8 PCR+ and with a clinical evolution in accordance with a Kaposi sarcoma, were HHV8+ on immunohistochemistry. In contrast, the 8 cases negative for HHV8 on immunohistochemistry were also PCR- and had a self-healing evolution in accordance with the diagnostic of pyogenic granuloma. CONCLUSION: : Detection of the latent nuclear antigen 1 of HHV8 by immunohistochemistry is a specific and sensitive diagnostic tool for differentiating Kaposi sarcoma from its mimics.

Antibodies, Monoclonal↗
PubMed2002

[Juvenile polyposis coli. The usefulness of a genetic study and the role of surgical treatment].

We report two cases of familial juvenile polyposis coli. SMAD4 gene mutation was found in our two patients, leading to the definite diagnosis. Colonic cancer occurred in the first patient. Long-term outcome was favorable after colectomy. In the second patient, prophylactic total colectomy was performed. Rectal bleeding, diarrhea, stomach obstruction and vomiting developed during the follow-up. Proctectomy, distal partial gastrectomy and total gastrectomy were successively performed.

Adenomatous Polyposis Coli↗