Characterization of a pure heterologous sarcoma of the uterus: rhabdomyosarcoma of the corpus

A case of a pure heterologous sarcoma of the uterine corpus composed exclusively of rhabdomyosarcomatous elements has been studied by multiple morphologic and biochemical techniques. The neoplasm filled the endometrial cavity and protruded out the cervical os, but the myometrium was only superficially invaded. The tumor did not extend outside the corpus. The pathologic features are discussed in detail. Evidence of striated muscle differentiation could be identified on light microscopic and ultrastructural examination. Immunoperoxidase staining of tumor cells with antibodies to myoglobin were positive. Histochemical preparations for lactate dehydrogenase, succinic dehydrogenase, and acid phosphatase were also positive in neoplastic cells. Other stains gave equivocal or negative results. These findings are discussed in comparison with previous reports.

A comparison between the activation of benzo[a]pyrene in organ cultures and microsomes from the tracheal epithelium of rats and hamsters

Epidermoid cancers of tracheal origin produced in Syrian golden hamsters and Fischer strain 344 rats are models for human bronchogenic carcinomas. These two species differ, however, in the sensitivity of their tracheal epithelia to tumor induction elicited by intratracheal benzo[a]pyrene (BP)-ferric oxide administration. The tracheas of hamsters are quite sensitive to the carcinogenic effects of BP-ferric oxide, but rat tracheas are apparently resistant to effects of comparable treatments by this route of administration. Rat tracheas are not completely resistant to polynuclear hydrocarbon carcinogenesis because in the heterotopic tracheal graft model, epidermoid carcinomas have been produced frequently. To determine whether differences in BP metabolism could explain this difference between species, quantitative kinetic and chromatographic studies of benzo[a]pyrene monoxygenase activity were carried out in epithelial microsomes and cells from organ cultures of rat and hamster tracheas. The Vmax was 2-fold greater in hamster tracheal cells than in rat tracheal cells whereas the Km values were identical. H.p.l.c. profiles from microsomes of rat and hamster tracheal epithelial cells incubated with BP exhibited extreme differences. Hamster tracheal microsomes produced large proportions of BP-quinones, BP-phenols, and BP-diols but rat tracheal microsomes produced mostly 3-OH BP. The total metabolic rate for BP in rat tracheal organ cultures was half that in cultures of hamster tracheas. The metabolites isolated in organ cultures of hamster and rat tracheas well reflected secondary reactions of conjugation and recycling. When evaluated with respect to the amount of tissue used, the most striking difference between rat and hamster tracheal organ cultures was in the amount of products which co-chromatographed with bay-region BP-tetrols. The amount of BP-tetrols produced by hamster tracheas was 0.22 pmol/mg tissue/24 h, and by rat, 0.012 pmol/mg tissue/24 h. The level of BP-DNA binding (in pmol/microgram DNA/24 h) catalyzed by hamster tracheal cells was 26.6 +/- 11.4, and by rat tracheas was 1.55 +/- 1.29. These interspecies differences associated with the formation of BP-diol epoxide, a presumed ultimate carcinogenic form of BP, are consistent with the differences between these two rodent species in susceptibility to carcinogenesis in this tissue.

Morphology and growth potential of stromal cell cultures derived from human endometrium

Propagable cell cultures derived from human endometrial tissue were determined to contain cells predominantly of stromal cell origin based on their morphologic resemblance to endometrial stromal cells. These features included nexi, solitary cilia, and predecidual cytology. In addition to morphology the cell cultures retained a normal karyotype and responded to steroid hormones as evidenced by cellular aggregation. The stromal cells were evaluated for a variety of characteristics associated with transformed cells and seemed to be biologically normal without neoplastic phenotypes. Growth potential of the stromal cell cultures was also characterized in normal maintenance medium, in nutritionally depleted medium with reduced levels of calcium or serum, and in medium with increased levels of serum. The prolonged survival of the stromal cells in vitro coupled with the retention of in vivo characteristics and an absence of neoplastic phenotype provides a human cell system that is amenable to a variety of long-term experimental analyses.

Monolayer culture of human endometrium: methods of culture and identification of cell types

Monolayer cultures can be established from human endometrial tissue after enzymatic dispersal into isolated glands or single cells. Three cell types that have distinct morphology by light and electron microscopy are observed in the resulting primary cultures. One cell type, an elongated spindle cell, is similar in appearance to fibroblasts derived from other tissues. A second cell type forms colonies of tightly cohesive cells, ranging in shape from oval to polygonal. These cells have typical organelles and junctional complexes characteristic of epithelial cells from the endometrium. The third cell type assumes a pavement-like appearance composed of polygonal cells when viewed by phase contrast microscopy, but lacks distinctive ultrastructural features of epithelial cells. These cells in culture resemble the endometrial stromal cell, the predominant cell type of the human endometrium in vivo. The epithelial cell does not survive subculturing but the other two cell types can be passaged through several generations and can be stored in liquid nitrogen and subsequently returned to culture.

Protection against endometrial carcinoma by combination-product oral contraceptives

Seventy-nine patients with endometrial carcinoma were compared with 203 control subjects regarding their use of combination-product oral contraceptives (OCs). Overall, 6.3% of patients and 15.3% of control subjects had used these products. The risk of endometrial cancer for users of OCs was less than half the risk for nonusers. Five years or more of use reduced the risk to a third. Recent users were strongly protected, whereas discontinuation resulted in risks returning to those of nonusers. Furthermore, OCs with predominantly progestational effects of intermediate formulations produced greater protection than those with predominantly estrogens. This pattern of results is biologically consistent with a protective effect of combination-product OCs against endometrial carcinoma.

DNA in proximity to the site of replication is preferentially alkylated in S phase 10T1/2 cells treated with N-methyl-N-nitroso-urea

Replicating DNA is more susceptible to modification by N-methyl-N-nitrosourea (MNU), a spontaneously active methylating agent, than bulk DNA. This conclusion is supported by results from two different experimental approaches. First, synchronized C3H 10T1/2 clone 8 cells were treated in S phase with MNU and DNA replicated during the period of treatment was separated from bulk DNA. This was done by digesting the purified DNA with restriction enzymes and retaining the replication fork-associated DNA in nitro-cellulose filters. Second, synchronized C3H 10T1/2 clone 8 cells were exposed to 5-bromodeoxyuridine and [3H]MNU and the density-labelled, replicated DNA was separated in CsCl gradients. Both methods show 2.6 to 5.0 times more [3H]methyl adducts per nucleotide residue associated with replicating DNA than that expected from random methylation. These experiments were done at low MNU concentrations (0.018-0.115 mM) that did not cause any detectable inhibition of DNA synthesis or stimulation of repair replication in 10T1/2 cells.

Risks of cervical intraepithelial neoplasia among DES-exposed women

The increased occurrence of cervical intraepithelial neoplasia (CIN) in women with in utero exposure to diethylstilbestrol (DES) is described. Among 335 self-referred women exposed to DES, 14.9% (50) had a least 1 cytologic smear interpreted as CIN, and 16.2% (54) had at least 1 biopsy interpreted as CIN. Excluding those with grade 1 CIN, 8.7% (29) had at least grade 2 CIN on biopsy and 4.2% (14) had biopsies interpreted as grade 3 CIN. No invasive lesions were detected. Because the problem of differentiating true intraepithelial neoplasia from morphologically indistinguishable but benign lesions in DES-exposed women remains unresolved, the authors believe a conservative approach to treatment is still indicated. This study supports the recommendation that DES-exposed women merit continued thorough gynecologic evaluation, including regular cytologic evaluation and colposcopy, with biopsies as indicated.

Reversible inhibition of rat hepatocyte proliferation by hydrocortisone and its effect on cell cycle-dependent hepatocarcinogenesis by N-methyl-N-nitrosourea

The susceptibility of hepatocytes to carcinogenesis in vivo may be influenced by the phase of the cell cycle at which carcinogen-induced damage is incurred. In order to better understand this relationship, hepatic cell proliferation in juvenile male Fischer 344 rats was charted following a two-thirds partial hepatectomy. For hepatocytes, two distinct waves of DNA synthesis occurred which were followed after 6 to 8 hr by waves of mitotic cell division. In contrast to this kinetic pattern, when hydrocortisone was given after the partial hepatectomy, the initial waves of DNA synthesis and mitosis by hepatocytes were each delayed by about 15 hr. In rats not given hydrocortisone, susceptibility to heptocarcinogenesis by N-methyl-N-nitrosourea was greatest at 20 hr after partial hepatectomy when the peak fraction of proliferating hepatocytes was in the S phase. By shifting the time of onset of DNA synthesis, the hydrocortisone treatments also shifted the time with greatest sensitivity to N-methyl-N-nitrosourea, with hepatocytes in late G1 or S again the most susceptible. Numerous tumors were also induced by N-methyl-N-nitrosourea in extrahepatic tissues, including intestine, Zymbal's gland, nervous system, kidneys, odontogenic tissues, and peritesticular mesothelium. The results illustrate the importance of cell proliferation in carcinogenesis and further point to the specific sensitivity of certain cell cycle phases.

Benzo(a)pyrene binding to DNA in organ cultures of human endometrium

Benzo(a)pyrene was found to bind to DNA in human endometrial tissue in vitro. Among specimens from 41 individuals examined, there was a 70-fold range in the observed specific activities of carcinogen binding to DNA. To determine whether this interindividual variability was correlated with the hormonally determined state of differentiation of the endometrial tissue, this population was subdivided to separate postmenopausal patients from premenopausal patients; among premenopausal patients, further division was made according to location within the menstrual cycle. Tissue obtained late in the proliferative phase or early in the secretory phase of the menstrual cycle had the highest mean specific activity of benzo(a)pyrene binding. In spite of the relatively small group sizes, the observed difference between this and the level of benzo(a)pyrene binding in the mid- and late secretory phases was statistically significant. The average binding level among the small number of patients studied who had entered a natural menopause was lower than the average binding for any of the subgroups of premenopausal patients and significantly lower than the mean for the whole population of premenopausal patients.

Cycle-dependent removal of certain methylated bases from DNA of 10T1/2 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine

The loss of N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-induced adducts from DNA was quantitated during the G1 and S phases of synchronously proliferating mouse 10T1/2 cells exposed to MNNG (2 microgram/ml) when they were in either confluence-induced arrest of proliferation or at the G2-S border. When treated at either time, N-7-methylguanine and O6-methylguanine were not excised from the template DNA during the subsequent S phase. However, both lesions were efficiently removed during the G1 phase immediately following exposure to MNNG, as well as during the second G2 phase after an S phase during which no loss occurrred. In contrast, N-3-methyladenine was lost rapidly during both the G1 and S phases following MNNG treatment. N-7 Methylguanine and O6-methylguanine were removed from logarithmically growing cell populations more slowly than from cells passing synchronously through the G1 phase. However, when the observed rate of loss in logarithmic cultures was corrected for the fraction of the logarithmic population located in the S phase, the rates of loss of the two methylated bases were the same as those observed in the G1 phase in synchronous cultures.

Benzo[a]pyrene metabolism in organ cultures of human endometrium

Twenty-six specimens of normal human endometrium were obtained for studies of [3H]benzo[alpha]pyrene metabolism in short-term organ culture. The tissues were capable of converting benzo[alpha]pyrene (BP) to oxygenated derivatives which co-chromatographed with dihydrodiols, quinones and monohydroxy derivatives of BP. A sulfate conjugate of a monohydroxy BP was also found among the acetone/ethyl acetate soluble products. When the acetone/ethyl acetate soluble metabolites were analyzed using high-pressure liquid chromatography (HPLC), the proportion of metabolites were found to vary greatly from specimen to specimen. Eight women smoked cigarettes but the BP metabolite profiles from organ cultures of endometrial tissue from these women did not differ from those who did not smoke. The average value for sulfate conjugates of monohydroxy BP was significantly lower in endometrial tissue from three postmenopausal women (ages 49, 57 and 58) than among premenopausal women. Specimens from premenopausal women which had been in organ culture for 2 weeks prior to the addition of [3H] BP produced metabolite profiles similar to those of specimens from postmenopausal women with a greatly reduced proportion of BP-phenol sulfate conjugates. These data suggest that the absence of hormonal stimulus (i.e., advanced age or conditions of organ culture) may affect the metabolism of BP in human endometrial tissue.

Predominance of early endometrial cancers after long-term estrogen use

Clinical stage and pathological characteristics of endometrial cancer cases were related to several aspects of estrogen prescribing. In comparing 256 cases with 321 community control subjects, estrogen use of less than 3 1/2 years' duration did not increase the risk of endometrial cancer for any stage, grade, histological type, or extent of ivasion. With long-term estrogen use (3 1/2 years or more), relative risks were significantly increased (5.2 to 7.6) for the early cancers--those clinically stage IA, histologically grade 1, and invading the endometrium only. These increases were seen with both high-dose (greater than 0.625 mg) and low-dose (less than or equal to 0.625 mg) preparations. Risks were only minimally increased for the more advanced cancers. However, long-duration estrogen use did produce an increased risk of advanced cancer when administration was continuous rather than cyclic.

"Alternative" controls in a case-control study of endometrial cancer and exogenous estrogen

To address the issue of detection bias among endometrial cancer cases and controls, women admitted to the North Carolina Memorial Hospital for dilatation and curettage (D&C) during 1970-1976 were selected as one of three control groups in a study of endometrial cancer and exogenous estrogen. Study subjects included 256 cases, 316 D&C controls, 224 gynecology controls and 321 community controls. The D&C controls had a higher frequency of estrogen use than either of the other control groups or the cases. These differences existed for both blacks and whites. When white cases were compared to either gynecology or community controls, relative risks were increased for long duration estrogen use and for recent use prior to diagnosis. With D&C controls, relative risks were not significantly different from unity irrespective of duration or recency of estrogen use. Exclusion of hyperplasias from the D&C controls had no substantive effect of these results. Bleeding was a presenting complaint for 92% of cases, 82% of D&C controls and 22% of gynecology controls. Both among cases and gynecology controls, there was no statistically significant association between bleeding and estrogen use, whereas this association was evident among D&C controls, and specifically among those who did not have pathologic evidence of endometrial hyperplasia. These data support the presence of detection bias among D&C controls but they do not provide evidence of this bias among endometrial cancer cases.

Cycle-related toxicity and transformation in 10T1/2 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine

Exposure of C3H 10T1/2 Cl 8 cells, synchronized by release from confluence-induced arest of proliferation, to different concentrations of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 30 min at various points during the cell cycle causes dose-dependent toxicity (decrease in relative colony-forming efficiency or "survival") that increases linearly during the first G1 phase, reaches a maximum in early to middle S phase, and decreases during late S. In the course of the second S phase, toxicity again becomes maximal. The transformation rate (type III foci) increases and decreases with a similar pattern, increasing during the first G1 phase to a maximum during early S phase, subsequently decreasing, and then increasing again during the second S phase. Although periods of maximal toxicity and transformation roughly coincide with some portion of the S phase, the mechanisms underlying these phenomena appear to differ for the following reasons: (a) toxicity is linearly related to dose of MNNG, whereas the latter is linearly related to the logarithm of transformation rate, and (b) the ratio between toxicity and transformation varies with the cycle phase and the dose of MNNG.

Induction of kidney tumours by a single dose of dimethylnitrosamine: dose response and influence of diet and benzo(a)pyrene pretreatment

Seven days on a protein-free diet increases the susceptibility of rats to the action of DMN as a renal carcinogen. The dose response for the induction of kidney tumours by a single dose of dimethylnitrosamine (DMN) in these rats is reported. The first tumour was not found until 28 weeks after the dose. At 100 weeks the incidence ranged from 22.5% at the lowest dose (20 mg/kg) to 97% at the highest dose (60 mg/kg). The incidence in probits at any time between 50 and 100 weeks was linearly related to the log dose. Epithelial and mesenchymal tumours were produced in an approximate ratio of 2:1. The protein-free diet alters the rate of metabolism of DMN in the rat, and increases the alkylation of nucleic acids by this carcinogen in the kidney. Further treatment of the rat with benzo(a)pyrene can reverse, to some extent, the change in metabolism, but does not reverse the change in alkylation. It is shown that the change in kidney-tumour incidence produced by the change in diet, and by the treatment with benzo(a)pyrene, corresponds to the changes these treatments produce in the alkylation of kidney DNA by the carcinogen.