No abstract

Whether peroxisome proliferator-activated receptor (PPAR) d is a good target for the chemoprevention and/or treatment of colorectal cancer (CRC) remains controversial. Our goal was to examine PPARd expression in multistage carcinogenesis of the colorectum and to assess the relevance of PPARd in CRC. Immunohistochemical analysis indicated that PPARd expression increased from normal mucosa to adenomatous polyps to CRC. In cancer tissues, the PPARd protein was accumulated only in those cancer cells with highly malignant morphology, as represented by a large-sized nucleus, round-shaped nucleus, and presence of clear nucleoli. Interestingly, the cancer tissue often contained both PPARd-positive and -negative areas, each retaining their respective specific morphological features. Moreover, this pattern persisted even when PPARd-positive and -negative cells were aligned next to each other within a single cancer nest or gland and was present in the majority of CRC cases. Immunohistochemistry for Ki-67 proliferation marker showed no significant correlation between Ki-67 and PPARd in CRC samples. Based on Western blot analysis and quantitative RT -PCR, high PPARd protein expression correlated with high PPARd mRNA levels. Peroxisome proliferator-activated receptor d may have a supporting role in tumorigenesis, and the close association between PPARd expression and malignant morphology of CRC cells suggests a pivotal role in cancer tissue.

Purpose: Although NY-ESO-1 was isolated from an esophageal carcinoma patient, its expression in this type of cancer and its immunogenicity in esophageal cancer patientshave not yet been fully elucidated. We report here the frequency of NY-ESO-1 mRNA and protein expression in esophageal cancer and the presence of NY-ESO-1-specific immune response in patients.Experimental Design: One hundred twenty three esophageal squamous cell carcinoma specimens were analyzed for the expression of NY-ESO-1 mRNA by conventional and real-time reverse transcription-PCR and the expression of protein by immunohistochemistry and Western blot. Sera and peripheral blood lymphocytes from 51 patients were analyzed for the NY-ESO-1 antibody production by enzymelinked immunosorbent assay and NY-ESO-1 T cell response by enzyme-linked immunospot assay. Survival analyses were also performed.Results: NY-ESO-1 mRNA was expressed in 41 of 123 (33%) esophageal squamous cell carcinoma specimens, and its expression was found at higher frequency in well-differentiated and moderately differentiated type of cancer. No mRNA copy was detected in any of the adjacent normal tissues. Twenty-one of 24 (87.5%) NY-ESO-1 mRNA-positive tumors were stained positively by immunohistochemistry. Correlation between the level of NY-ESO-1 mRNA expression and the degree of immunohistochemistry positivity was observed. Antibody production was observed in 2 patients with tumors that showed protein expression. Furthermore, a CD8 T-cell response against NY-ESO-1 was observed in 1 of the 2 seropositive patients.Conclusions: The high expression frequency of NY-ESO-1 mRNA and protein indicates NY-ESO-1 as a feasible vaccine target in esophageal cancer.

Purpose: Our aim was to determine the effects of cyclin D1 inhibition on tumor-associated neovascularization and endothelial cell growth. Experimental Design: We have generated adenovirus system for antisense to cyclin D1 (AS CyD1) and evaluated in vitro and in vivo effects. Small interfering RNA against cyclin D1 was also used to analyze cyclin D1 inhibition-associated vascular endothelial growth factor (VEGF) regulation. Results: The xenografts treated with adenoviral AS CyD1 showed less vessel density and displayed smaller tumor size in colon cancer cell lines HCT116 and DLD1. In vitro studies indicated that AS CyD1 decreased VEGF protein expression in DLD1 but not in HCT116. Cyclin D1 small interfering RNA caused a decrease in VEGF expression at protein and RNA levels in DLD1. A modest decrease was noted in the VEGF promoter activity, with inactivation of the STAT3 transcription factor through dephosphorylation. On the hand, the cyclin D1inhibition plus STAT3 inhibitor markedly decreased VEGF expression in HCT116, although VEGF did not change by the STAT3 inhibitor alone. In cultures of human umbilical vein endothelial cells (HUVEC), VEGF augmented cyclin D1expression and cell growth. AS CyD1significantly inhibited HUVEC growth even in the presence of VEGF. AS CyD1 also significantly suppressed in vitro tube formation in VEGF-treated HUVEC and in vivo macroaneurysm formation inVEGF-treated Matrigel plug. Conclusions: Our results suggest that cyclin D1 may play a role in the maintenance of VEGF expression and that AS CyD1could be potentially useful for targeting both cancer cells and their microenvironment of tumor vessels.Cyclin D1, a putative G 1 cyclin, preferentially associates with CDK4 and positively regulates the cell cycle transition from G 1 to S phase (1). Cyclin D1 is considered an oncogene because forced expression in rodent fibroblasts induces tumorigenicity in nude mice and cyclin D1 transgenic mice develop tumors of breast, esophagus, stomach, and tongue (2 -4). In human carcinomas, increased expression of cyclin D1 is one of the most frequent abnormalities because it is detected in f60% of breast cancers, 40% of colorectal cancers, 40% of squamous carcinomas of the head and neck, and 20% of prostate cancers (5 -8). Furthermore, overexpression of cyclin D1 is associated with poor prognosis of patients with carcinomas of colorectum, esophagus, stomach, pancreas, and liver (9 -13). Therefore, cyclin D1 is a crucial target for various types of human malignancies.To suppress the malignant potential of carcinomas, the strategy of antisense to cyclin D1 (AS CyD1) was first assessed in human esophageal squamous cell carcinoma and colon cancer cells (14,15). These studies clearly showed that AS CyD1 reversed the transformed phenotype of tumor cells, inhibited cell growth of tumor cells, and resulted in loss of tumorigenicity. Subsequently, AS CyD1 was found to enhance chemosensitivity of 5-fluorouracil, mitoxantrone, and cisplatinum in pancreatic cancer cells and head and neck cancer cells and...

Recent studies have shown that the cyclin-dependent kinase (CDK) inhibitor p27^Kip1 represents an indicator for patients’ outcome in several human malignancies including gastric cancer. However, the clinicopathologic value of another class of CDK inhibitor, p16^INK4, has not been determined. In a retrospective study, we examined the expression of p16^INK4 by immunohistochemical assay of 80 samples of primary gastric cancers and their adjacent nonneoplastic mucosas. Less than 10% of non-tumor gastric mucosal cells were p16^INK4 positive, whereas the expression of p16^INK4 in gastric cancer cells varied widely from 0 to 100% (mean, 24.5%). The expression of p16^INK4 was not seen in 11.3% (9/80) of the cancer cases, but in 65% (52/80) this protein was even overexpressed when compared with the nonneoplastic mucosa. A clinicopathologic survey indicated that a low or no expression of p16^INK4 was associated with poorly differentiated carcinoma (p = 0.0133), but the level of expression did not correlate with other parameters including patients’ prognosis or with the expression of the pRb protein. In an effort to explore the underlying mechanism for the p16^INK4-negative cases, a prospective study was also performed on 20 cases of gastric cancer to compare the level of the p16^INK4 protein with the methylation status of the p16^INK4 promoter. Gastric cancer tissues with methylation expressed significantly lower levels of the p16^INK4 protein (p = 0.0013) and two of them lacked p16^INK4 expression altogether, whereas all the cancer tissues without methylation expressed it. These findings suggest that the p16^INK4 protein may be associated with differentiation of gastric cancer tissues and that methylation of the p16^INK4 promoter may, in part, account for the loss of p16^INK4 expression.