Ras oncoprotein expression and jackfruit lectin binding in rectal carcinoma

Expression of the ras oncogene product p21 and Jack fruit lectin (JFL) bind ing were analyzed in 12 samples of normal rectal tissue, 18 adenomas and 45 carcinomas. Mild expression of ras p21 was observed in 6 of the 12 normal rectal tissue, Three of the six samples expressed N-ras p21, tao expressed K-ras p21 and the remaining one H-ras p21, In adenoma, expression of 3 ras proteins ranged from mild to moderate, The expression of N-ras p21 was maxi mum in the carcinoma cases, with 91% of samples showing inmunoreactivity, K -ras p21 was seen in 58% of the cases while H-ras p21 expression was seen i n 53% of cases. Correlation analysis revealed significant association betwe en positive p21 immunoreactivity and increasing histological abnormality (r = 0.74; p < 0.000 for N-ras; r = 0.53; p < 0.05 for H-ras and I = 0.62; p = 0.03 for K-ras), JFL binding on the other hand, was found to be reduced w ith increasing histologic abnormality. Normal rectal epithelium showed inte nse binding with over 60% cells showing a positive reaction. Adenomas were seen to have moderate to intense staining with a range of 30-60% positive c ells, Lowest levels of JFL binding was associated with invasive tumors, A s ignificant negative association was thus extent between JFL binding and his tological abnormality (r = -0.64, p <0.000). A negative correlation was als o evident between expression of N-ras and K-ras oncoproteins and JFL bindin g (r =-0.64, p <0.000 and r =-0.63, p < 0.001 respectively). These results suggest that ras oncoprotein expression during rectal tumorigenesis is acco mpanied by cell surface glycoprotein alterations.