No abstract

DNA ploidy of 64 colorectal adenomas and 49 adenocarcinomas, examined endoscopically, was studied by flow cytometry. We found DNA aneuploidy in none of the 105 normal mucosa samples (O%), in 20 adenomas (31%), and in 36 adenocarcinomas (74%). DNA ploidy of adenomas correlated with size ( P = 0.02) and degree of dysplasia ( P < 0.01) but not with histologic type. Adenomas had a 45% incidence of DNA aneuploid stem lines in the DNA index range of 0.80-1.20, compared with 8% in the case of adenocarcinomas. The distribution of the DNA index values of adenocarcinomas was approximately normal, with a mean value 1.63 f 0.28. The mean DNA index for the three cases of "carcinoma in adenoma" with invasion of the stalk of the adenoma was 1.52 f 0.18. These results, using DNA flow cytometry, provide evidence for the progression of colorectal adenoma to adenocarcinoma. The classification of adenomas according to DNA ploidy may be information of considerable practical value to the clinician in predicting risk of further adenomas andlor risk of cancer.

Recent studies indicate that p21ras proteins mediate their multiple cell functions through interactions with multiple effectors and that the number of new effectors is growing. We recently reported that K-ras2 mutations in human colorectal adenomas were associated with chromosome instability and proliferation changes. In the present study , we extend these previous observations. Hereditary and multiple (n > 5) adenomas and adenomas with early cancer were excluded. Dysplasia was moderate in 91 cases and high in 25, and the median adenoma size was 1.5 cm. K-ras2 spectrum analysis was done by sequence-specific oligonucleotide hybridization using nuclear suspensions provided by analysis and sorting of multiparameter flow cytometry. In particular , tissue inflammatory cells were separated for DNA diploid tumors, whereas DNA aneuploid epithelial subclones were analyzed separately. K-ras2 mutations and DNA aneuploidy were both detected in 29 of 116 (25%) cases. DNA aneuploid index was in the near-diploid region in the majority of cases. DNA aneuploidy was strongly associated with G3 C/T transversions. An association was also found between low S-phase values and G3 A transitions. These findings were confirmed using multivariate logistic regression analysis to account for the effects of size , dysplasia , site , type , age, and sex. These data suggest that specific K-ras2 mutations in a subgroup of human sporadic colorectal adenomas play a role in chromosome instability and, contrary to expectations , are associated with inhibition of proliferation. (Am J Pathol 1998, 153:1201-1209)Ras proteins participate at the plasma membrane level in transduction of diverse extracellular physiological signals that are thought to induce appropriate gene expression toward proliferation and differentiation. Ras proteins possess an intrinsic GTPase activity and alternate between activated and inactivated forms. The best-known Ras transduction mechanism is a pathway from receptor tyrosine kinases to transcription factors phosphorylated by mitogen-activated protein kinases. Mutations of the ras oncogenes result in constitutive signaling to downstream elements and are detected at high frequency in many types of human cancer.

N-(4-hydroxyphenyl)retinamide (HPR) is a synthetic retinoid with anti-cancer properties and lower toxicity than all-trans retinoic acid (RA). Neuroblastoma cells treated with HPR and observed by fluorescence microscopy showed clear signs of apoptosis, such as chromatin condensation and margination, nuclear fragmentation and the presence of "apoptotic bodies". Moreover, measurements on a cell-by-cell basis by the flow-cytometric DNA-content in situ-terminal-deoxinucleotidyl-transferase(TDT) assay showed that apoptosis induced by HPR was dose- and time-dependent and that the fraction of apoptotic cells increased from approximately 15% at 1.25 microM at 2 days after treatment up to approximately 90% at 5 microM and 8 days of continuous treatment. Additionally, we found that cells were induced into apoptosis independently from the cell-cycle phase. In contrast, equimolar or higher doses of RA, from 5 microM to 80 microM, were able to inhibit growth by differentiation, but failed to induce apoptosis. We conclude that the functional effects of HPR and RA in LA-N-5 neuroblastoma cells are mediated by apoptosis and differentiation respectively, suggesting a potential clinical use of HPR in the management of neuroblastoma patients.

Pretreatment tumor Tpot appears to be an important independent prognostic factor for local control of HN-SCC treated by primary radiotherapy.