X-Ray Sensitivity and DNA Synthesis in Synchronous Populations of HeLa Cells

Terasima, Toyozo; Tolmach, L. J.

doi:10.1126/science.140.3566.490

Cited by 227 publications

(79 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Hence, inhibiting oxidant production by flavin oxidases in cancer cells under conditions that do not induce DNA double-strand breaks in these cells or the neighboring normal cells becomes an attractive adjuvant cancer therapy. Further, most tumors harbor proliferating cells that are distributed in the different phases of the growth cycle, which significantly impacts radiation sensitivity (Terasima and Tolmach, 1963). Blocking cells in G 1 , by inhibiting flavin-containing oxidases, could result in depletion of tumor cells from the relatively radioresistant S-phase compartment, thereby enhancing radiosensitivity and therapeutic response.…”

Section: Discussionmentioning

confidence: 99%

Regulation of normal cell cycle progression by flavin-containing oxidases

Prakash¹,

Toledo²,

Pandey³

et al. 2007

Oncogene

View full text Add to dashboard Cite

Mechanisms underlying the role of reactive oxygen species (ROS) generated by flavin-containing oxidases in regulating cell cycle progression were examined in human and rodent fibroblasts. Incubation of confluent cell cultures with nontoxic/nonclastogenic concentrations of the flavoprotein inhibitor, diphenyleneiodonium (DPI), reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase activity and basal ROS levels, but increased proteolysis of cyclin D1, p21 Waf1 and phospho-p38 MAPK . When these cells were allowed to proliferate by subculture in DPI-free medium, an extensive G 1 delay was observed with concomitant activation of p53/p21 Waf1 signaling and reduced phosphorylation of mitogen-activated kinases. Compensation for decreased oxidant generation by simultaneous exposure to DPI and nontoxic doses of the ROS generators, c-radiation or t-butyl-hydroperoxide, attenuated the G 1 delay. Whereas the DPI-induced G 1 checkpoint was completely dependent on PHOX91, ATM and WAF1, it was only partially dependent on P53. Interestingly, G 1 to S progression was not affected when another flavin-containing enzyme, nitric oxide synthase, was inhibited nor was it associated with changes in mitochondrial membrane potential. Proliferating cells treated with DPI also experienced a significant but attenuated delay in G 2 . We propose that ATM performs a critical function in mediating normal cellular proliferation that is regulated by nonphagocytic NAD(P)H oxidase enzymes activity, which may serve as a novel target for arresting cancer cells in G 1 .

show abstract

Section: Discussionmentioning

confidence: 99%

Regulation of normal cell cycle progression by flavin-containing oxidases

Prakash¹,

Toledo²,

Pandey³

et al. 2007

Oncogene

View full text Add to dashboard Cite

show abstract

“…Furthermore, the in vitro sensitivity assay may produce false-positive results in cases where drug-induced cell cycle perturbation is not accompanied by cell kill (10,17), and false-negative results with drugs that kill cells equally in all parts of the cell cycle.…”

Section: Discussionmentioning

confidence: 99%

Chemosensitivity of human small cell carcinoma of the lung detected by flow cytometric DNA analysis of drug‐induced cell cycle perturbations in vitro

Engelholm

Spang‐Thomsen

Vindeløv³

et al. 1986

Cytometry

View full text Add to dashboard Cite

A method based on detection of drug-induced cell cycle perturbation by flow cytometric DNA analysis has previously been described in Ehrlich ascites tumors as a way to estimate chemosensitivity. The method is extended to test human small-cell carcinoma of the lung. Three tumors with different sensitivities to melphalan in nude mice were used. Tumors were disaggregated by a combined mechanical and enzymatic method and thereafter have incubated with different doses of melphalan. After incubation the cells were plated in vitro on agar, and drug induced cell cycle changes were monitored by flow cytometric DNA analysis. Melphalan produced a dose-related S phase accumulation in the two sensitive tumors, whereas no changes in the cell cycle distribution were found in the resis- In vitro tests, especially the human tumor cloning assay (12,13), have been increasingly used to optimize treatment of malignant diseases andor to test new and more potent non-cross-resistant drugs. However, the human tumor cloning assay is time-consuming and requires 2-3 wk before conclusive results are available. Furthermore, the method does not allow one to test how representative the growing cells are. In search of a faster technique to detect chemosensitivity, a method based on measurements of drug-induced cell cycle perturbations was examined in experimental tumors (5). This in vitro flow cytometry assay was found to be able to detect sensitivity to adriamycin in Ehrlich ascites tumors.The object of the present study was to determine whether the in vitro cell cycle perturbation assay could be extended to test the chemosensitivity of human solid tumors. This demands a valid procedure to disaggregate the solid tumors into single cell suspensions representative of the original tumors. Three heterotransplanted human small-cell carcinomas of the lung (SCCL) were selected for this study because of their different sensitivities to melphalan (9). The tumors were disaggregated by a combined mechanical and enzymatic method (7).Subsequently the cells were incubated in vitro with different doses of melphalan; flow cytometric DNA analysis was used to monitor drug-induced cell cycle pertubations.The results showed that melphalan induced dose-related S phase accumulations in two sensitive tumors, whereas no cell cycle changes were found in a resistant tumor. Furthermore, the size of the S phase accumulation in vitro reflected the previously found in vivo chemosensitivity of the tumors. Thus, the results suggest that the flow cytometry method applied on disaggregated tumor cells may be extended to sensitivity testing of human tumors in general, including screening for new agents. MATERIALS AND METHODS Tumors

show abstract

“…We therefore consider it possible to modify and extend the methods as a sensitivity test for human malignant tumours. However, therapy-induced cell cycle perturbations which are not accompanied by cell kill (Terasima & Tolmach, 1963) may prove to be a limitation in using flow cytometry for in vitro sensitivity testing.…”

Section: Discussionmentioning

confidence: 99%

A short-term in vitro test for tumour sensitivity to adriamycin based on flow cytometric DNA analysis

Engelholm¹,

Spang‐Thomsen²,

Vindeløv³

1983

Br J Cancer

View full text Add to dashboard Cite

(Hamburger, 1981). A currently-used test is based on measuring the druginduced inhibition of the colony-forming ability of tumour cells grown in soft agar (Hamburger & Salmon, 1977 (Vindelov et al., 1982(Vindelov et al., , 1983 (Dan0, 1971;1972a;1972b;Skovsgaard, 1977a;1977b;1979) were kindly supplied by Dr. T. Skovsgaard, Dept. Internal Medicine, Finsen Institute, Copenhagen. One of the tumours ("wild-type") was sensitive to adriamycin (as well as to other anthracyclines) and was previously found to be hypotetraploid. The other two tumours were adriamycin-resistant and were previously characterized as hypotetraploid and hyperdiploid, respectively. Tumour cells used in the experiments were harvested 6-8 days after i.p.

show abstract

X-Ray Sensitivity and DNA Synthesis in Synchronous Populations of HeLa Cells

Cited by 227 publications

References 21 publications

Regulation of normal cell cycle progression by flavin-containing oxidases

Regulation of normal cell cycle progression by flavin-containing oxidases

Chemosensitivity of human small cell carcinoma of the lung detected by flow cytometric DNA analysis of drug‐induced cell cycle perturbations in vitro

A short-term in vitro test for tumour sensitivity to adriamycin based on flow cytometric DNA analysis

Contact Info

Product

Resources

About