Primary retroperitoneal spindle cell liposarcoma: pathological and immunohistochemical findings.

Spindle cell liposarcoma (SCLS) is presently regarded as a rare variant of well-differentiated liposarcoma (WDLPS), which has the potential for aggressive clinical behavior. WDLPS occurs most frequently in the limbs and retroperitoneum. The most common site of SCLS occurrence is the upper limbs or shoulder girdle. Herein we report the first case of primary retroperitoneal SCLS. A 60-year-old Japanese man presented with a right inferior abdominal mass. Complete excision of the mass displayed a yellowish spherical tumor with a well-circumscribed appearance measuring 98 x 95 mm. Pathological examination of the tumor revealed a neural-like spindle cell proliferation set in a fibrous background that was associated with an atypical lipomatous component, which usually included lipoblasts. Mitotic cells were scarce. Immunohistochemical analysis demonstrated that lipoblasts were S100 positive, spindle cells were CD34 positive, and both spindle cells and lipoblasts were MDM2 negative. The Ki-67 labeling index was <2%. At one year follow up, the patient was alive without local recurrence or metastasis. Although the proliferative activity of this tumor did not indicate strong malignancy, retroperitoneal liposarcoma generally has a poor prognosis. Accumulation of cases of SCLS is necessary to facilitate a more accurate evaluation of the pathology and clinical behavior of this tumor.

DNA hypomethylation at the CpG island is involved in aberrant expression of the L1 cell adhesion molecule gene in colorectal cancer.

The L1 cell adhesion molecule (L1CAM) has been identified as a target gene of beta-catenin-TCF signaling in colorectal cancer (CRC) and associated with aggressive tumor behavior such as invasion and metastasis. We investigated the methylation status at the L1CAM gene promoter and/or L1CAM mRNA/protein expression in 4 CRC cell lines and 71 primary CRCs. Aberrant L1CAM expression was immuno histochemically observed in 31 (43.7%) of 71 cases, and correlated with advanced stage and presence of lymph node and distant metastases (P<0.05). Treatment with a demethylating agent induced L1CAM mRNA/protein expression in two cell lines lacking L1CAM expression. Bisulfite-modified genome sequencing suggested that DNA methylation status at core promoter and putative TCF-binding sites within the L1CAM promoter was correlated with L1CAM mRNA/protein expression in 4 CRC cell lines. Using the crypt isolation followed by bisulfite-modified genome sequencing and methylation-specific PCR methods, we confirmed that the DNA hypomethylation at core promoter and putative TCF-binding sites was well correlated with the aberrant L1CAM protein expression in primary CRC samples. These results suggest that DNA hypomethylation at the L1CAM CpG islands might induce L1CAM aberrant expression and contribute to the acquisition of aggressive tumor behavior in CRC.

[A novel anticancer drug delivery system -DAC-70/CDDP].

We devised a muco-adhesive anticancer drug delivery system using 70% deacetylated chitin (DAC-70) and cisplatin (CDDP) and 5-fluorouracil (5-FU). The adhesive force between the system and human colonic mucosa was measured ex vivo, and a release profile of each drug was examined in vitro. Each system demonstrated a stronger muco-adhesive force at 37 degrees C than that of 25 degrees C. The CDDP-loaded system showed a sustained release of the drug while the 5-FU-loaded system exhibited an initial bursting of the agent. We presume that the release profile of CDDP and 5-FU is closely related to both degradability of the chitin and interactions between the chitin and each drug. The DAC-70/CDDP system would be clinically promising in loco-regional cancer chemotherapy.

Epigenetic status and aberrant expression of the maspin gene in human hepato-biliary tract carcinomas.

We examined expression of maspin and the epigenetic status of its gene in 40 primary hepato-biliary tract carcinomas and 11 cell lines originating from hepato-pancreatico-biliary tract carcinomas. Aberrant maspin expression was frequently observed immunohistochemically in biliary tract carcinomas (22/25, 88%) but not in hepatocellular carcinomas (HCCs) (0/15, 0%). Aberrant maspin expression by five pancreatico-biliary tract carcinoma cell lines was closely associated with demethylation at the maspin promoter. Five of six HCC cell lines were maspin-negative and exhibited extensive hypomethylation and hypoacetylation at the maspin promoter. Treatment with 5-aza-2'-deoxycytidine did not activate maspin expression in these five maspin-negative HCC cell lines, whereas treatment with Trichostatin A (TSA) activated maspin expression in two of them. Treatment with TSA increased histone acetylation in some HCC cell lines. These results suggest that aberrant maspin expression in biliary tract carcinomas is closely associated with demethylation at the promoter region, but that some HCC cell lines additionally require histone acetylation. In addition, the fact that maspin-negative HCC cell lines remain after treatment with TSA suggests the existence of other repressive factors controlling maspin expression.

Human PinX1, a potent telomerase inhibitor, is not involved in human gastrointestinal tract carcinoma.

PinX1 was isolated as a Pin2/TRF1 binding protein that also binds to the telomerase catalytic subunit hTERT. The gene is a potent telomerase inhibitor and a putative tumor suppressor since it inhibits telomerase activity and affects tumorigenicity in nude mice. This study investigated aberrations of PinX1 gene in gastrointestinal tract carcinomas (GITCs). We examined mutations, mRNA expression and promoter methylation of PinX1 gene in 15 GITC cell lines, and 20 patients with primary GITC. We found a missense mutation at codon 254 (AGC/TGC) in a colon and an esophageal carcinoma cell line, and in cancerous and matching normal tissues of 2 patients with primary GITC (10%). It might be a benign polymorphism. No hyper-methylation was found in the promoter region and the treatment by 5-Aza-2'-deoxycytidine did not affect PinX1 mRNA expression level in any of the cell lines. It was concluded that the human PinX1 does not affect tumorigenesis of human GITC.

Disruption of cell-type-specific methylation at the Maspin gene promoter is frequently involved in undifferentiated thyroid cancers.

Cancer-associated DNA hypomethylation is as prevalent as cancer-linked hypermethylation, but the biological significance of DNA hypomethylation in carcinogenesis is less understood. The expression of Maspin (mammary serpin) in differentiated normal cells is regulated by epigenetic modifications in a cell-type-specific manner. Paradoxical Maspin expression due to epigenetic modification has been addressed in several cancer cell types. To elucidate the role of the Maspin gene in thyroid cancer, we studied methylation status in the promoter region and its expression in six human undifferentiated thyroid cancer cell lines and in specimens from 92 primary thyroid tumors, consisting of six follicular adenomas, 56 well-differentiated thyroid cancers (WDTCs), 17 poorly differentiated thyroid cancers (PDTCs) and 13 undifferentiated thyroid cancers (UDTCs). Three of the six cell lines overexpressed Maspin mRNA and its protein product, but the remaining three did not. The methylation status at the promoter region was inversely correlated with Maspin expression. In Maspin-negative cell lines, Maspin expression was induced by treatment with 5-aza-2'-deoxycytidine, a DNA demethylating agent. Immunoreactivity for Maspin protein was frequently detected in UDTCs (8/13, 62%) and PDTCs (7/17, 41%). Immunoreactivity for Maspin was diffusely positive in UDTCs, and was restricted to dedifferentiated components of the tumor in PDTCs. Positive immunoreactivity was infrequent in WDTCs (1/56, 2%), and all follicular adenomas and normal thyroid glands were completely negative. Their methylation status evaluated by the methylation-specific PCR method showed a good inverse correlation with their immunoreactivity in surgically resected specimens. Our data suggest that overexpression of Maspin by DNA hypomethylation is closely associated with morphological dedifferentiation in thyroid cancers.