POSITIVE CORRELATION BETWEEN CALMODULIN CONTENT AND HEPATOMA GROWTH-RATES

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (7) , 2571-2574
Abstract
Calmodulin contents of normal rat liver, host liver [bearing hepatoma 5123t.c.(h)], regenerating liver, and Morris hepatomas 7800, 5123t.c.(h), and 7794A were determined by phosphodiesterase assay and by radioimmunoassay. The calmodulin levels determined by both assays were significantly increased in 3 hepatomas when compared to the corresponding values of normal liver. The order of increase in calmodulin content was as follows: normal liver = host liver < 7794A (slow growth rate) < 5123t.c.(h) (intermediate growth rate) < 7800 (fast growth rate). In regenerating liver (24 h after partial hepatectomy), the calmodulin content was not different from that of normal liver. In good agreement with the literature, the calmodulin values measured by the phosphodiesterase assay were always lower than those determined by radioimmunoassay. Ca and Mg contents were measured by atomic absorption spectrophotometry in acid digests of these tissues. Both cation contents were significantly increased in the 3 hepatomas studied when compared to the corresponding values of normal liver; the extent of increase for Ca content (120-240%) was much greater than that for Mg (30-40%). The order of increase for both cations was as follows: normal liver = host liver < 5123t.c.(h) < 7794A < 7800. Therefore, there does not appear to be any correlation between the cation contents and hepatoma growth rates. In regenerating liver, Mg content was .apprx. 14% higher than that of normal liver, whereas Ca content was not significantly different from normal liver. Only the increase of calmodulin appears to correlate positively with the growth rate of these tumors. This correlation suggests that calmodulin may be involved in tumor cell growth regulation.