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We demonstrated previously that the effect of cis-diamminedichloroplatinum(II) (cisplatin) against pancreatic cancer was substantially enhanced by the addition to the chemotherapeutic regimen of 1-beta-D-arabinofuranosylcytosine and caffeine. To obtain information on the factors influencing tumor response to this combination treatment, we investigated two adenocarcinomas of the exocrine pancreas grown in the nude mouse, tumors Capan-1 and SW-1990. Tumor response to cisplatin, characterized by tumor regression and tumor growth arrest, was observed when it was given in the upper limits of tolerance (5 mg/kg). Caffeine and 1-beta-D-arabinofuranosylcytosine singly and in combination had no effect on tumor growth; neither did they influence the effect of cisplatin when combined singly with the latter. However, the triple combination of cisplatin, 1-beta-D-arabinofuranosylcytosine, and caffeine resulted in complete tumor regression. The enhancing effect of the triple combination depended on tumor sensitivity to cisplatin and the amount of cisplatin administered and required rather large amounts of caffeine. The present report indicates that certain combination regimens may enhance the therapeutic effect of cisplatin against pancreatic carcinoma.

The biological behavior of a number of nude mouse-grown human epithelial tumors of different histogenetic background was studied. They included three transitional cell carcinomas and a mucin-producing carcinoma of the urinary bladder, two pancreatic adenocarcinomas, a colon adenocarcinoma, a breast ductal carcinoma, and an epidermoid carcinoma. Microinvasion was a constant finding in all tumors examined. All but one of the tumors studied showed macroinvasion and metastases. Tumors transplanted s.c. in the anterior aspect of the lateral thoracic wall metastasized primarily to the regional and mediastinal lymph nodes. In certain cases, systemic metastases were observed affecting the submaxillary, contralateral axillary, and inguinal lymph nodes. Lung metastases occurred through the lymphatic and hematogenous routes. It is concluded that the nude mouse-grown human tumors investigated in the present study show overt malignant behavior recapitulating the biological characteristics of the tumor of origin.

The modifying roles of age, sex, and strain of mice on the incidence, multiplicity, and spectrum of tumors induced by benzo(a)pyrene have been investigated. The first-generation (F1) hybrids of C57BL/6J X C3HeB/FeJ and C3HEB/Fej X A/J mice of both sexes were given single i.p. injections (75 or 150 mug/g) of benzo(a)pyrene at 1, 15, or 42 days of age. Experimental animals were allowed to live their life-spans, while animals in control groups were killed at 52, 90, 142, or 170 weeks of age. Animals treated with benzo(a)pyrene died, in general, by the 100th week of age due to development of liver, lung, stomach and lymphoreticular tumors. Few of the control animals died during that same observational period. The age of mice at the time of exposure to the carcinogen modified development of tumors at all the sites. The sex of animals influenced the development of liver and lymphoreticular tumors. The C3HeB/FeJ X A/J F1 hybrids developed lung tumors more readily than did the C57BL/6J X C3HeB/FeJ F1 mice, which had significantly more liver tumors and neoplasms of the lymphoreticular system than the former strain. No strain difference was observed in regard to tumors at other sites. Higher doses of benzo(a)pyrene were more effective in inducing lung, liver, and stomach tumors. In addition, 5 cases of pancreatic ductal adenoma and adenocarcinoma were observed in carcinogen-treated mice.

The effect of cisplatin, carboplatin, and mitoguazone dihydrochloride on pancreatic cancer was evaluated using pancreatic ductal adenocarcinomas Capan-1, Capan-2, and PR54 grown in the nude mouse. In single agent treatments, cisplatin, given in the amount of 5 mg/kg once/week for 4 consecutive weeks, was most effective, resulting in tumor regression, growth arrest, and a growth delay period of 6 and 4 months for tumors Capan-1 and PR54, respectively. Treatment with carboplatin was less effective, with a tumor response related to treatment schedule. For the same amount of total dose of carboplatin administered, best results were obtained when treatment was given 3 times weekly instead of in single weekly injections. Mitoguazone dihydrochloride exhibited no antitumor effect. The results of the present work may be of significance in the management of pancreatic cancer patients.

Human pancreatic ductal adenocarcinoma Capan-2, derived from a 56-yr-old male Caucasian, has been studied in both tissue culture and the nude mouse. In tissue culture, tumor cells showed epithelial-like features, whereas in the nude mouse, the tumor grew as a well-differentiated adenocarcinoma, resembling histopathologically the original neoplasm. Ultrastructurally, the neoplastic cells showed characteristics of ductal epithelium. The allozyme phenotypic profile of Tumor Capan-2 was determined in eight genetically determined loci, and chromosome studies showed a hypotetraploid pattern with a number of morphological and numerical changes. Carcinoembryonic antigen was produced in trace amounts, and lactate dehydrogenase was represented only by Isoenzyme 5, regardless of environmental conditions. The characteristics of Capan-2 tumor make it a valuable addition to the small number of available pancreatic tumor lines in studies aiming at clarifying certain aspects of the biology of this type of malignancy.

A new tumor line derived from a human pancreatic ductal adenocarcinoma of a 56-year-old Caucasian male was established in tissue culture and the nude mouse. In tissue culture, the neoplastic cells grew as large, epithelial-like, mucin-producing cells. Injection s.c. of 1 X 10(6) cultured neoplastic cells into nude mice resulted in tumor formation histologically closely resembling the original neoplasm. Ultrastructurally, the neoplastic cells showed characteristics of ductal epithelium. The allozyme phenotypic profile of the line was established in 14 genetically determined loci, and chromosome studies showed a near-tetraploid pattern. Production of macromolecules such as lactate dehydrogenase and carcinoembryonic antigen were present in measurable amounts in culture media, tumor cell extracts, nude mouse-grown tumors, and the serum of tumor-bearing mice in amounts relative to tumor size. Pancreatic enzymes were not detected. These characteristics make tumor line SW-1990 a valuable tool in studying various aspects of the biology of human pancreatic cancer.

The morphological, biological, biochemical, and karyotypic characteristics of four human bladder transitional cell carcinoma lines, SW-780, SW-800, SW-1738, and SW-1710, were investigated. In tissue culture, each cell line presented a distinct phenotypic expression. All but line SW-1710 grew when transplanted in the nude mouse. Light and electron microscopic studies showed morphological characteristics similar to the tumors of origin, being independent of the passages in tissue culture medium, tumor cell extracts, and the plasma of nude mouse-grown tumors, showing isoenzyme quantitative distribution typical for each cell line. In addition, each cell line exhibited a unique genetically determined enzyme phenotypic profile which, along with the karyotypic analysis, makes their identification feasible. These characteristics make the described tumor lines a valuable tool in studying various aspects of the biology of human bladder transitional cell carcinoma.

A comparative study of the effect of cis-diamminedichloroplatinum(II) (cisplatin), diammine[1,1-cyclobutanedicarboxylato(2-)-O,O'-platinum] (carboplatin), and mitoguazone dihydrochloride on urothelial cancer was conducted using transitional cell carcinomas of the urinary bladder grown in the nude mouse. Tumors SW-780 and TCC-K1 represented transitional cell carcinoma, Grade II, whereas Tumor PR49 represented a fast-growing Grade III neoplasm. Of the agents studied, cisplatin was most effective, resulting in tumor response related to the dose administered. Response to carboplatin was clearly related to treatment schedule. For the same amount of total dose administered, better results were obtained when treatment was given three times weekly instead of once every week. Furthermore, cisplatin was more effective against the less differentiated PR49 tumor in contrast to carboplatin, which showed more activity against the better differentiated SW-780 and TCC-K1 tumors. None of the tumors tested responded to mitoguazone dihydrochloride. The results of the present study may assist in formulating better treatment modalities against urothelial cancer, taking into account factors such as tumor grade, growth rate, treatment schedule, and the patient's tolerance which may ultimately influence tumor response.

The growth characteristics and biological behavior of human tumors transplanted s.c. into two different anatomical regions of nude mice were studied. It was observed that tumors trnasplanted in the anterior lateral thoracic wall grew faster than did tumors transplanted in the posterior aspect of the trunk. Anteriorly growing tumors, in contrast to the posteriorly transplanted ones, were better vascularized, showed less necrosis, invaded the tumor bed, and metastasized to the regional lymph nodes. These findings were independent of their histogenetic and morphological characteristics. It is concluded that regional vascular supply is a key factor influencing the biological behavior of the transplanted tumors and that it may affect tumor response to treatment as well.

The response of lymphoreticular tissues to a single i.p. injection of benzo(a)pyrene was studied in the first generation of C57BL/6J X C3HeB/FeJ F1 and C3HeB/FeJ X A/J F1 mice. Groups of 1-, 15-, and 42-day-old animals of both sexes received 75 or 150 mug of the carcinogen per g body weight. After a period of approximately 90 weeks, a high incidence (up to 43%) of reticulum cell sarcomas was observed in C57BL/6J X C3HeB/FeJ F1 mice treated with benzo(a)pyrene at 40 days of age. Animals treated with carcinogen at younger ages had a lower incidence of reticulum cell sarcomas. These sarcomas showed marked cellular pleomorphism and were classified into histiocytic, epitheloid-nodular, reticulocytic, and fibrocytic forms according to the predominant cell type. Lymphomas of thymic and extrathymic lymphoid origin and leukemia of granulocytic type were seen in a descending order of frequency. Control animals of either strain that were killed at 90 weeks of age were basically free of lymphoreticular tumors, while those kept under observation up to 170 weeks developed these tumors in 24% (C57BL X C3H F1) and 10% (C3H X A/J F1), respectively. Studies revealed that the augmentation and/or acceleration of development of the lymphoreticular neoplasms and specifically reticulum cell sarcomas by benzo(a)pyrene was dependent upon the strain and sex of mice used and the age at which the animals were exposed to carcinogen.

The growth characteristics and metastatic behavior of human tumors growing in athymic nude mice were studied. Human tumor cell lines HEp-2 (carcinoma or larynx) and SW480 (colon carcinoma) were transplanted into athymic nude mice of BALB/c origin. Tumor cells (1 x 10(6) and 2 x 10(7)) were given either s.c. or i.p. Following s.c. injection tumors developed rapidly to become easily palpable with 2 weeks forming a s.c. tumor focus surrounded by a thick fibrous capsule. Animals with s.c. transplants were little affected by the growing tumor. At the time they were sacrificed at Day 34 (HEp-2) and 62 (SW480), a large part of the tumor was necrotic. Capsular infiltration and invasion of lymphatic vessels and perineural and perivascular lymphatic spaces were observed. Metastases to regional lymph nodes were seen in animals kept alive for up to 6 months. Following i.p. transplantation, tumors spread widely in the peritoneal cavity, invaded intraabdominal organs, and metastasized to mediastinal lymph nodes and lungs. Fifteen of 26 animals (60%) developed metastases. Necrosis of the i.p. growing tumors was minimal. All animals in this group died as a result of tumor growth.