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The primary in vitro antitumor screening of "half-mustard type" phenothiazines
M A Wuonola1, M G Palfreyman, N Motohashi
1SCRIPTGEN Pharmaceuticals, Inc., Medford, MA 02155, USA.
Abstract:
The antitumor effects of "half-mustard type" phenothiazines were studied on 57 different tumor cell lines, including leukemias, non-small lung cancer, colon, central nervous system, ovarian, renal, breast, and prostate cancer, as well as melanoma cell cultures. Alkyl-urea derivatives of phenothiazines displayed in vitro antitumor activity. The phenothiazine phthalimido derivatives (1-6) were not active on the majority of cancer cell cultures. In contrast, propylureas (9, 11) were active against some leukemia cell types. Only two compounds with the butylene [(CH2)4] linker (10, 12) were active against non-small lung cancer cells. Compounds containing the propylene linker were less effective. On colon cancer lines, tumor cells from the central nervous system and on melanoma cells the same compounds were effective, however, having substituents at the 2-position of phenothiazine seems to be important. Surprisingly, the majority of ovarian cancer cell lines (except one type, IGROVI) and five of eight renal cancer lines were not sensitive to these phenothiazine derivatives. The two butylene linked phenothiazine ureas (10, 12) had moderate antiproliferative action on two renal cancer cell lines. The prostate cancer and some breast cancer cell lines were not sensitive. Nevertheless some breast cancer cell lines were apparently sensitive to CF3-substituted phenothiazine alkylureas. On the basis of these experiments one may postulate that in the case of insensitive cells an mdr-gene encoded multidrug resistance efflux pump is responsible for the resistance. The selectivity or organ cell specificity of the effective phenothiazines will be targeted for improvement in further studies, in order to avoid the general cytotoxic effects of "half mustard type" phenothiazines.
Insights
Phenothiazine derivatives show antitumor activity against various cancers, with specific structures effective against leukemia and lung cancer. Resistance in some cancer cells may be due to multidrug resistance pumps, guiding future drug development.
Area of Science:
- Medicinal Chemistry
- Cancer Research
- Pharmacology
Background:
- Phenothiazines, particularly "half-mustard type" derivatives, are investigated for their potential anticancer properties.
- Understanding the structure-activity relationships of these compounds is crucial for developing targeted cancer therapies.
Purpose of the Study:
- To evaluate the in vitro antitumor effects of various phenothiazine derivatives across a broad spectrum of human cancer cell lines.
- To identify specific phenothiazine structures with selective activity against different cancer types.
- To explore potential mechanisms of drug resistance in cancer cells treated with phenothiazines.
Main Methods:
- Screening of 57 different tumor cell lines, including leukemias, lung, colon, central nervous system, ovarian, renal, breast, and prostate cancers, as well as melanoma.
- Synthesis and testing of alkyl-urea and phthalimido derivatives of phenothiazines.
- Evaluation of structure-activity relationships based on linker length (propylene vs. butylene) and substituent position (e.g., 2-position, CF3).
Main Results:
- Alkyl-urea phenothiazine derivatives demonstrated in vitro antitumor activity.
- Propylurea derivatives were active against certain leukemia cell types, while butylene-linked compounds showed activity against non-small lung cancer.
- Activity against colon, central nervous system, and melanoma cells was observed, with 2-position substituents appearing important. Ovarian and renal cancer cells showed variable sensitivity.
- Some breast cancer cell lines responded to CF3-substituted phenothiazine alkylureas, while prostate and other breast cancer lines were insensitive.
Conclusions:
- Phenothiazine derivatives exhibit differential antitumor activity across various cancer cell lines, suggesting potential for targeted therapy.
- Multidrug resistance (MDR) mechanisms, possibly involving mdr-gene encoded efflux pumps, may contribute to the insensitivity of certain cancer cells.
- Further research should focus on enhancing the organ cell specificity of effective phenothiazines to improve therapeutic outcomes and minimize general cytotoxicity.
