Resolution of Benign and Malignant Sebaceous Neoplasms, in a Renal Transplant Patient Treated With Everolimus.

Nonmelanoma skin cancers are the most common malignancies in transplant recipients under immunosuppression; nevertheless, appendage tumors also may appear. The onset of several cutaneous neoplasms in transplant patients can cause deterioration in quality of life of these patients. A 62-year-old white woman patient developed several malignant and benign sebaceous neoplasms during an immunosuppressive treatment for a renal transplant. The genetic study showed a mutation in MSH6-eson 1 (c116G>A), without mutations in MLH1 gene and MSH2. A final diagnosis of multiple sebaceous tumors in an immunosuppressed patient without Muir -Torre syndrome was made. The spreading of further cutaneous neoplasms led to a change in immunosuppression: namely, that clinicians suspended tacrolimus and add everolimus. After 2 months, all tumor lesions on the face and on the limbs have disappeared, and no further lesions occurred. Everolimus could represent a valid therapeutical treatment for transplant patients at high risk for cutaneous tumors. A genetic consult and a consequent study of the genetic profile should be performed on each of these patients, to avoid risks of recurrent cutaneous tumors and negative effects on the quality of life.

Dual role of inactivating Lef1 mutations in epidermis: tumor promotion and specification of tumor type.

The NH(2) terminus of LEF1 is frequently mutated in human sebaceous tumors. To investigate how this contributes to cancer, we did two-stage chemical carcinogenesis on K14DeltaNLef1 transgenic mice, which express NH(2)-terminally truncated Lef1 in the epidermal basal layer. Transgenic mice developed more tumors, more rapidly than littermate controls, even without exposure to tumor promoter. They developed sebaceous tumors, whereas controls developed squamous cell carcinomas. K14DeltaNLef1 epidermis failed to up-regulate p53 and p21 proteins during tumorigenesis or in response to UV irradiation, and this correlated with impaired p14ARF induction. We propose that LEF1 NH(2)-terminal mutations play a dual role in skin cancer, specifying tumor type by inhibiting Wnt signaling and acting as a tumor promoter by preventing induction of p53.

K-ras mutations in lung tumors and tumors from other organs are consistent with a common mechanism of ethylene oxide tumorigenesis in the B6C3F1 mouse.

Ethylene oxide is a multisite carcinogen in rodents and classified as a human carcinogen by the National Toxicology Program. In 2-year mouse studies, ethylene oxide (EO) induced lung, Harderian gland (HG), and uterine neoplasms. We evaluated representative EO-induced and equivalent spontaneous neoplasms for K-ras mutations in codons 12, 13, and 61. K-ras mutations were identified in 100% (23/23) of the EO-induced lung neoplasms and 25% (27/108) of the spontaneous lung neoplasms. Codon 12 G to T transversions were common in EO-induced lung neoplasms (21/23) but infrequent in spontaneous lung neoplasms (1/108). K-ras mutations were found in 86% (18/21) of the EO-induced HG neoplasms and 7% (2/27) of the spontaneous HG neoplasms. Codon 13 G to C and codon 12 G to T transversions were predominant in the EO-induced HG neoplasms but absent in spontaneous HG neoplasms (0/27). K-ras mutations occurred in 83% (5/6) of the EO-induced uterine carcinomas and all were codon 13 C to T transitions. These data show a strong predilection for development of K-ras mutations in EO-induced lung, Harderian gland, and uterine neoplasms. This suggests that EO specifically targets the K-ras gene in multiple tissue types and that this event is a critical component of EO-induced tumorigenesis.

High frequency of codon 61 K-ras A-->T transversions in lung and Harderian gland neoplasms of B6C3F1 mice exposed to chloroprene (2-chloro-1,3-butadiene) for 2 years, and comparisons with the structurally related chemicals isoprene and 1,3-butadiene.

Chloroprene is the 2-chloro analog of 1,3-butadiene, a potent carcinogen in laboratory animals. Following 2 years of inhalation exposure to 12.8, 32 or 80 p.p.m. chloroprene, increased incidences of lung and Harderian gland (HG) neoplasms were observed in B6C3F1 mice at all exposure concentrations. The present study was designed to characterize genetic alterations in the K- and H-ras proto-oncogenes in chloroprene-induced lung and HG neoplasms. K-ras mutations were detected in 80% of chloroprene-induced lung neoplasms (37/46) compared with only 30% in spontaneous lung neoplasms (25/82). Both K- and H-ras codon 61 A-->T transversions were identified in 100% of HG neoplasms (27/27) compared with a frequency of 56% (15/27) in spontaneous HG neoplasms. The predominant mutation in chloroprene-induced lung and HG neoplasms was an A-->T transversion at K-ras codon 61. This mutation has not been detected in spontaneous lung tumors of B6C3F1 mice and was identified in only 7% of spontaneous HG neoplasms. In lung neoplasms, greater percentages (80 and 71%) of A-->T transversions were observed at the lower exposures (12.8 and 32 p.p.m.), respectively, compared with 18% at the high exposure. In HG neoplasms, the percentage of A-->T transversions was the same at all exposure concentrations. The chloroprene-induced ras mutation spectra was similar to that seen with isoprene, where the predominant base change was an A-->T transversion at K-ras codon 61. This differed from 1,3-butadiene, where K-ras codon 13 G-->C transitions and H-ras codon 61 A-->G transitions were the predominant mutations. The major finding of K-ras A-->T transversions in lung and Harderian gland neoplasms suggests that this mutation may be important for tumor induction by this class of carcinogens.

Carcinogenicity of N1-[tris(hydroxymethyl)]methyl-4-nitro-o-phenylenediamine fed to mated and non-mated Sprague-Dawley rats.

N1(-)[tris(hydroxymethyl)]methyl-4-nitro-o-phenylenediamine was fed in the diet to groups of 30 male and 55 female Sprague-Dawley rats at levels of 0.2, 0.6 and 2.0% for up to 6 months. One mid-dose and two high-dose females developed palpable mammary masses that were subsequently diagnosed as mammary adenocarcinomas at a 13-wk interim kill involving 10 rats/sex/group. After 14 wk, 25 females per group with no apparent masses were mated in a reproduction/teratology study. Mammary tumours developed in a dose-related fashion both in the pregnant rats and in the remaining 20 females/group that continued on treatment for 6 months. On gestation day 20 (wk 17-18) the final incidences of mammary adenocarcinomas in the low-, mid- and high-dose mated dose groups were 20, 60 and 84%, respectively, while the corresponding incidences in the non-mated females at 6 months were 5, 40 and 85%. Most mammary tumours were encapsulated but, at 6 months, lung metastases were noted in four rats, and four females also had Zymbal's gland tumours. Non-neoplastic changes in male and female rats considered to be related to treatment included increases in thyroid follicular cell size accompanied by an accumulation of golden-brown pigment, multifocal hepatic necrosis with non-suppurative inflammation, and renal tubular pigmentation. Increases in foetal variations in the mid- and high-dose groups were considered to be related non-specifically to retarded growth. Malformations observed in the high-dose group were found primarily in single foetuses and were not considered to be treatment related. Although the mean numbers of micronucleated polychromatic erythrocytes in bone marrow obtained from high-dose treated females after 13 wk slightly exceeded historical negative control values, the data were not considered indicative of a genotoxic effect because of the absence of either a dose relationship or a substantive increase in the frequency of micronucleated cells.

High frequency and low specificity of ras gene mutations in rat Zymbal's gland tumors induced by 2-amino-3-methylimidazo[4,5-f]quinoline.

The activating mutations of all three ras genes in rat Zymbal's gland tumors induced by a food mutagen, 2-amino-3-methylimidazo[4,5- f]quinoline (IQ) were analyzed. DNA fragments of the Ha-ras, Ki-ras and N-ras oncogenes were amplified from formalin-fixed and paraffin-embedded tissues by the polymerase chain reaction (PCR) and analyzed for activating mutations involving codons 12, 13 and 61 by oligonucleotide differential hybridization. All nine Zymbal's gland tumors examined, including three papillomas, were found to contain either an Ha-ras or Ki-ras mutation. These mutations were located in either codon 13 or 61 of Ha-ras, and in either codon 12 or 13 of Ki-ras. Of the nine mutations, three were G-->T, three were G-->C, two were G-->A and one was A-->T. Of the nine mutations, eight occurred at guanine bases and seven were transversions. There was no correlation between the types of mutations and the histological types of the tumors. These results suggest that ras gene activation is an important early event in the tumorigenesis induced by IQ in rat Zymbal's gland and that mutations at guanine bases are frequent, though the locations and types of the mutations are not highly specific.

Tumor-initiating activity and carcinogenicity of dibenzo[a,l]pyrene versus 7,12-dimethylbenz[a]anthracene and benzo[a]pyrene at low doses in mouse skin.

Dibenzo[a,l]pyrene (DB[a,l]P) is an extremely potent carcinogen that may be present in environmental samples. Dose-response studies were conducted at low doses in mouse skin by initiation-promotion and repeated application to compare its activity to that of 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (B[a]P), DB[a,l]P-8,9-dihydrodiol and DB[a,l]P-11,12-dihydrodiol. Female SENCAR mice were initiated with 1 or 0.25 nmol of DB[a,l]P, DMBA, B[a]P or DB[a,l]P-11,12-dihydrodiol and promoted with phorbol ester acetate. At 1 nmol, DB[a,l]P induced 2.6 tumors/mouse, whereas DB[a,l]P-11,12-dihydrodiol and DMBA induced 0.17 and 0.29 tumors/mouse respectively. At the low dose, DB[a,l]P induced 0.79 tumors/mouse, but the other two compounds were virtually inactive. B[a]P, tested only at 1 nmol, was inactive. These three compounds, as well as DB[a,l]P-8,9-dihydrodiol, were tested by repeated application twice weekly for 40 weeks at 1 and 4 nmol per dose. In addition, DB[a,l]P, DMBA and B[a]P were also tested at 8 nmol. At 8 and 4 nmol, DB[a,l]P induced malignant tumors in 91 and 70% of mice respectively. At 4 nmol DB[a,l]P-11,12-dihydrodiol elicited only benign tumors in 36% of mice. At 4 nmol DMBA induced two carcinomas in one mouse and at 8 nmol it induced one papilloma and one sebaceous gland adenoma. B[a]P and DB[a,l]P-8,9-dihydrodiol were inactive at all doses tested. These results demonstrate that DB[a,l]P is a much more potent carcinogen than DMBA, the aromatic hydrocarbon previously considered to be the most potent. Combination of these results with previous comparisons of DB[a,l]P, DB[a,l]P-11,12-dihydrodiol, DMBA and B[a]P at higher doses (E.L. Cavalieri et al. (1991) Carcinogenesis, 12, 1939-1944) shows clearly the interference of toxicity with the tumorigenicity of DB[a,l]P and its 11,12-dihydrodiol.

Induction of tumors in the Japanese house musk shrew, Suncus murinus (Insectivora), by dimethylbenz[a]anthracene.

The carcinogenic effect of 7,12-dimethylbenz[a]anthracene (DMBA) was examined in the virgin female Japanese house musk shrew, Suncus murinus (family: Soricidae, order: Insectivora). Leukemia, musk gland tumors, pilosebaceous tumors and sarcomas were induced in the DMBA-treated shrews, whereas none of the controls developed any tumors up to 50 weeks of age. DMBA emulsion was administered i.p. at a dose of 1.25 or 2.5 mg once a week, with either four or eight doses being given from 8 weeks of age. Leukemia developed in 100% (9/9), 50% (5/10), 56% (5/9) and 0% (0/10) of the animals treated with a total dose of 20 mg (8 x 2.5 mg), 10 mg (8 x 1.25 mg), 10 mg (4 x 2.5 mg) and 5 mg (4 x 1.25 mg) of DMBA respectively. Leukemia was of the lymphatic and/or mast cell type, and the spleen was the organ invariably involved. A dose-dependent effect of DMBA was not observed for pilosebaceous and musk gland tumors. When 1 mg of DMBA powder was dusted into the subcutaneous tissue at 4 weeks of age, sarcomas developed at the dusted site (69%; 9/13).

Mutational activation of c-Ha-ras gene in squamous cell carcinomas of rat Zymbal gland induced by carcinogenic heterocyclic amines.

The activation of the c-Ha-ras gene and its carcinogen specificity were examined in squamous cell carcinomas (SCCs) induced by the mutagenic heterocyclic amines 2-amino-3-methylimidazo [4,5-f]quinoline (IQ),2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) in the Zymbal gland in rats. DNA fragments of the c-Ha-ras gene were amplified from formalin-fixed and paraffin-embedded tissues by polymerase chain reaction and analyzed for activating mutations involving codons 12, 13, and 61 by oligonucleotide differential hybridization and sequencing. c-Ha-ras mutations were found in four of seven and two of six Zymbal gland SCCs induced by IQ and MeIQx, respectively. These mutations were located in either codon 13 or 61. In the case of MeIQ, point mutations at the second nucleotide of codon 13 were found in nine of the total 14 Zymbal gland SCCs and in one papilloma. Of the nine SCCs that had mutations in codon 13, two possessed mutations at the second nucleotide of codon 12 as well. Most reported mutations in c-Ha-ras are located at codon 12 or 61, but the heterocyclic amines in this study induced mutations not only at codons 12 and 61 but also in codon 13. Transversions were the dominant mutation induced by these heterocyclic amines.

No evidence of toxicity or carcinogenicity of pentaerythritol tetranitrate given in the diet to F344 rats and B6C3F1 mice for up to two years.

Toxicology and carcinogenesis studies of pentaerythritol tetranitrate (PETN), an organic nitrate used in explosives and as a therapeutic agent for angina pectoris, were conducted by administering diets containing PETN,NF (National Formulary Grade, a 1:4 mixture of PETN and lactose) to both sexes of F344 rats and B6C3F1 mice in 14-day, 13-week and 2-year studies. PETN was found to be essentially non-toxic in 14-day and 13-week studies at dietary concentrations as high as 10,000 ppm; the weight gain of female rats was lower than that of controls at 5000 and 10,000 ppm in the 13-week study. In the 13-week studies, one in ten high-dose female rats had an adenoma of the Zymbal gland and one in ten high-dose female mice had a hepatocellular adenoma. Dietary concentrations chosen for the 2-year studies were 5000 and 10,000 ppm for male rats and male and female mice, and 1240 and 2500 ppm for female rats. In the 2-year studies, there were no adverse effects on survival or body weight gains in either sex of rats or mice. No neoplastic or non-neoplastic lesions were considered to be related clearly to PETN administration. Neoplasms of the Zymbal gland occurred at low incidences in PETN-exposed groups of both sexes of rats in the 2-year study.

Dermal toxicity and carcinogenicity of 4-vinyl-1-cyclohexene diepoxide in Fischer rats and B6C3F1 mice.

4-Vinyl-1-cyclohexene diepoxide (VCHD) is used as a chemical intermediate and as a reactive diluent for diepoxides and epoxy resins. Studies were conducted by administering VCHD in acetone by dermal application, 5 days per week for 105 weeks, to groups of 60 rats of each sex at 0, 15, or 30 mg/animal. Groups of 60 mice of each sex were administered 0, 2.5, 5, or 10 mg/animal on the same schedule for up to 103 weeks. Ten animals from each group were humanely killed, necropsied, and examined histopathologically during Month 15. At the 15-month evaluation, 2 of 10 male rats that received 30 mg had a squamous cell carcinoma of the skin at or adjacent to the site of application. Squamous cell papillomas and carcinomas were seen in all mice that received 5 or 10 mg. Two of nine female mice given 10 mg had granulosa cell tumors of the ovary, and one of nine female mice given 10 mg had an ovarian papillary cystadenoma. In the 2-year studies, body weight and survival were lower in high-dose rats and mid- and high-dose mice than in vehicle controls. All high-dose male mice died by Week 83; remaining high-dose female mice were killed during Week 84 for humane reasons. Squamous cell papillomas of the skin in dermally exposed male rats and squamous cell carcinomas and basal cell adenomas or carcinomas of the skin in exposed male and female rats were increased. The incidence of squamous cell carcinomas of the skin was increased in male and female mice at all dose levels. Mid- and high-dose female mice had an increased incidence of benign or malignant granulosa cell tumors and of benign mixed tumors of the ovary.

Effects of dietary perilla oil, soybean oil and safflower oil on 7,12-dimethylbenz[a]anthracene (DMBA) and 1,2-dimethyl-hydrazine (DMH)-induced mammary gland and colon carcinogenesis in female SD rats.

The effects of diet supplemented with perilla oil, which contains a large amount of n-3 alpha-linolenic acid, and n-6 linoleic acid rich soybean and safflower oil supplemented diets on 7,12-dimethylbenz[a]anthracene (DMBA)- and 1,2-dimethylhydrazine (DMH)-induced mammary gland and colon carcinogenesis were investigated in female SD rats. Groups of 23 or 24, 5 week old animals were first given three s.c. injections of 40 mg/kg body wt DMH followed by a single intragastric administration of 50 mg/kg body wt DMBA within 2 weeks of the commencement. Starting 1 week after the DMBA treatment, they were administered pellet diet containing 10% perilla oil, soybean oil or safflower oil for the succeeding 33 weeks. Histological examination revealed that the resultant numbers of mammary tumors per rat were significantly lower in rats given perilla oil diet (4.4 +/- 2.5) than in the soybean oil diet group (6.5 +/- 3.9). Furthermore, colon tumor incidence was significantly lower in animals receiving the perilla oil supplement (18.2%) than in those given safflower oil diet (47.4%), and the numbers of colon tumors per rat tended to be lowest in rats administered perilla oil. Also the incidence of nephroblastomas in rats receiving perilla oil diet (0%) was significantly lower than that for the soybean oil diet group (23.8%). The results thus indicate that the alpha-linolenic acid (n-3)-rich perilla oil diet inhibits development of mammary gland, colon and kidney tumors as compared to linoleic acid (n-6)-rich safflower or soybean oil diet.

[Modifying effects of beraprost sodium (TRK-100) on N-methyl-N-nitrosourea (MNU) carcinogenesis in F344 rats].

The potential tumor-promoting effects of beraprost sodium (TRK-100), stable analogue of prostacyclin (PGI2), were investigated in rats pretreated with N-methyl-N-nitrosourea (MNU) which is a potent initiator of tumor development in a variety of organ or tissues. Male F344 rats were initially given injections of MNU (20 mg/kg b.w. i.p.) twice a week for 3 weeks, and then administered drinking water containing 6, 2, 0.7 or 0.2 ppm of beraprost sodium for the next 29 weeks. For comparison, positive control groups received N-propyl-N-nitrosourea (PNU), which is a carcinogen in hematopoietic system and small intestine on F344 rat, at the dose of 200, 50 and 12.5 ppm in their drinking water. Appropriate non-treated controls were also included. Numerous tumors were observed in many organs including the hematopoietic system, digestive tract, nervous system, Zymbal's gland (auditory sebaceous glands) and peritoneal mesothelium. However, no tumor-enhancing effects of beraprost sodium were observed. In contrast, the groups treated with PNU demonstrated increased development of tumors in the tongue, forestomach, large intestine and Zymbal's gland. These results thus indicate that beraprost sodium is not capable of modulating the development of MNU-induced tumors.

Induction of tumors in the Zymbal gland, oral cavity, colon, skin and mammary gland of F344 rats by a mutagenic compound, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline.

A mutagenic compound, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, which was first isolated from broiled sardines and was shown to be carcinogenic to mice, was also found to be carcinogenic to F344 rats. It induced tumors in various organs, such as the Zymbal gland, oral cavity, colon, skin and mammary gland of male and female rats when given at 0.03% in the diet. However, it was noteworthy that tumors were not observed in the liver. Most of the tumors in the Zymbal gland, oral cavity and skin were squamous cell carcinomas, and most of the mammary gland tumors were adenocarcinomas. The colon tumors were identified as adenomas or adenocarcinomas. In control rats no tumors developed in these organs during the 40-week experiment.