Relationships among Tenascin Expression, DNA Ploidy Patterns, and Multidrug Resistance Gene Product (P‐Glycoprotein) in Human Colon Carcinoma

Relationships among tenascin expression, DNA ploidy, and P‐glycoprotein were examined in 81 primary human colon cancers and 61 metastatic lymph nodes. First, the DNA ploidy patterns of colon cancerous tissue surrounded (TN(+)) and not surrounded (TN(−)) by tenascin immunoreactivity were investigated. Then the expression of P‐glycoprotein, one of two multidrug resistance gene products, was examined in TN(+) and TN(−) colon cancer tissues by immunohistochemistry. Aneuploid DNA patterns were observed at high frequency in TN colon cancer tissues (37/61) and metastatic lymph nodes (44/52). In contrast, diploid DNA patterns were observed predominantly in TN(+) colon cancer tissues (50/56). Although P‐glycoprotein expression was observed in primary TN(+) and TN(−) colon cancer (9/81), the level of P‐glycoprotein expression was not correlated with DNA aneuploidy in TN(−)colon cancer tissues. Overall, reduced tenascin expression was correlated well with DNA aneuploidy, but no significant correlation was found between DNA aneuploidy and P‐glycoprotein appearing when cancer cells become resistant to several anti‐cancer drugs. Thus, tenascin may play an important role in preventing colon cancer cells from invading surrounding tissues.