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[Intracellular effect of hydroxyalkenals on animal tumors (author's transl)]
Abstract:
When incubated for 30 min in vitro, 4-hydroxyalkenals in a 5 x 10-3 M solution react with SH-groups of soluble cytoplasmic and nuclear proteins (ProtL-SH) of Morris hepatomas 9618 A and 5123 tc, and of Ehrlich ascites tumor (EAT) cells. The extent of the reaction strongly increases with decreasing doubling time of the respective tumors. Former experiments with EAT cells have shown that the reaction with cytoplasmic ProtL-SH causes inhibition of respiration, glycolysis, and probably of other SH-controlled processes associated with cell division. The intranuclear reaction leads to an inhibition of DNA- and RNA-synthesis. In a 2 x 10-4 M solution of hydroxyalkenals, however, the reaction with cytoplasmic ProtL-SH diminishes almost completely so that no measurable inhibition of respiration and only 3% inhibition of glycolysis are observed, while 20 to 30 percent of the nuclear ProtL-SH are still blocked. This corresponds well with a previous observation that a 2 x 10-4 M solution of hydroxypentenal inhibits DNA-synthesis by 90 percent.
Insights
4-hydroxyalkenals inhibit tumor cell division by reacting with protein sulfhydryl (SH) groups. Lower concentrations block nuclear protein SH-groups, inhibiting DNA synthesis, while higher concentrations affect cytoplasmic SH-groups, impacting respiration and glycolysis.
Area of Science:
- Biochemistry
- Cell Biology
- Oncology
Context:
- 4-hydroxyalkenals are reactive aldehydes implicated in cellular damage.
- Tumor cells exhibit varying proliferation rates, influencing their susceptibility to cytotoxic agents.
- Sulfhydryl (SH) groups on proteins are crucial for various cellular functions.
Purpose:
- To investigate the differential reactivity of 4-hydroxyalkenals with protein SH-groups in tumor cells.
- To correlate the extent of SH-group modification with tumor doubling time and cellular processes.
- To determine the impact of varying 4-hydroxyalkenal concentrations on cytoplasmic and nuclear protein functions.
Summary:
- In vitro incubation of Morris hepatomas and Ehrlich ascites tumor (EAT) cells with 5 x 10-3 M 4-hydroxyalkenals showed increased reaction with protein SH-groups (ProtL-SH) correlating with faster tumor doubling times.
- Cytoplasmic ProtL-SH reactions inhibited respiration and glycolysis, while nuclear ProtL-SH reactions inhibited DNA and RNA synthesis.
- At a lower concentration (2 x 10-4 M), 4-hydroxyalkenals primarily blocked nuclear ProtL-SH (20-30%), significantly inhibiting DNA synthesis (90%) with minimal impact on cytoplasmic functions.
Impact:
- Demonstrates a concentration-dependent, differential effect of 4-hydroxyalkenals on tumor cell biochemistry.
- Highlights the critical role of nuclear protein SH-groups in DNA synthesis regulation.
- Provides insights into potential therapeutic strategies targeting tumor cell proliferation via SH-group modification.