No abstract

Cytochrome P450 (CYP)-dependent drug metabolism decreases in vivo and in cultured hepatocytes under various immunostimulatory conditions. Nitric oxide (NO) released during inflammation is presumed to be involved in this phenomenon. CYP3A4, which is abundant in the liver and small intestine and participates in the metabolism of various drugs, is known to be induced by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in the colon carcinoma cell line Caco-2. In this study we examined whether NO affected CYP3A4 gene expression induced by 1,25(OH)2D3 in Caco-2 cells. Induction of CYP3A4 mRNA by 1,25(OH)2D3 was suppressed in a dose-dependent manner by treatment with the NO donors NOR-4 (15-500 microM) or S-nitroso-N-acetylpenicillamine (30 microM-1 mM), which spontaneously release NO. These results indicated that NO has an inhibitory effect on the induction of CYP3A4 mRNA by 1,25(OH)2D3 in Caco-2 cells. Treatment with the guanylate cyclase inhibitor ODQ failed to prevent the inhibition of induction of CYP3A4 mRNA by 1,25(OH)2D3. 8-Bromo cGMP had no effect on 1,25(OH)2D3-induced CYP3A4 gene expression. Therefore, the suppression of CYP3A4 mRNA by NO might be mediated through a guanylate cyclase-independent pathway.

Orthotopic implantation of a metastatic cell line of Lewis lung carcinoma (LLC-MLN), which was isolated by an in vivo selection method, resulted in greater metastatic growth in mediastinal lymph nodes as compared with that of the original LLC cells. LLC-MLN cells also had increased invasive ability and activator protein-1 (AP-1) transcriptional activity as compared with the original LLC cells. This is well consistent with the previously reported finding that overexpression of AP-1 is associated with lymphatic metastasis in lung cancer patients. Oral administration of curcumin, which downregulates AP-1 transcription, significantly inhibited the mediastinal lymph node metastasis of orthotopically implanted LLC cells in a dose-dependent manner, but did not affect the tumor growth at the implantation site. Combined treatment with curcumin and an anti-cancer drug, cis-diamine-dichloroplatinum (CDDP), resulted in a marked inhibition of tumor growth at the implanted site and of lymphatic metastasis, and a significant prolongation of the survival time. The downregulation of transcriptional AP-1 activity by curcumin as seen in the dual luciferase assay caused inhibition of LLC cell invasion through the repression of expression of the mRNAs for urokinase-type plasminogen activator (u-PA) and its receptor (u-PAR). Inhibition of AP-1 transcriptional activity may offer improved therapeutic efficacy for lung cancer patients with lymphatic metastasis.

This study was designed to establish an intrahepatic metastasis model to investigate the biology and therapy of hepatocellular carcinoma (HCC) in mice. A fragment of mouse HCC tumor CBO140C12 was orthotopically implanted into the mouse liver. The number of intrahepatic metastatic colonies and the volume of the implanted tumor increased in a time-dependent manner. At 28 days after fragment implantation, all mice showed intrahepatic metastasis. Intravenous administrations of cisplatin and doxorubicin at 7 and 21 days after the implantation significantly suppressed the growth of the primary tumor nodule, but tended to inhibit intrahepatic metastasis. However, a marked decrease of body weight was observed during the experiment. On the other hand, an inhibitor of matrix metalloproteinases (MMPs), ONO-4817, decreased the gelatinase activity of MMP-9 secreted by CBO140C12 cells, and significantly reduced the number of colonies of intrahepatic metastasis when administered orally. Our established model, which is focused on intrahepatic metastasis, is suitable for evaluating the therapeutic effect of HCC and for analyzing intrahepatic metastasis, because this model reflects the clinical features of HCC and all the steps of tumor metastasis. Key words: Intrahepatic metastasis -Hepatocellular carcinoma -Metastasis model -Orthotopic implantation -MMP inhibitorDespite recent advances in imaging techniques for the diagnosis of hepatocellular carcinoma (HCC), improvements in surgical procedures, and the introduction of new therapies such as transarterial embolization and percutaneous ethanol injection therapy, the prognosis of patients with HCC remains relatively poor.1) The reason for this is the high frequency of recurrence within the liver.2) Intrahepatic metastasis is one of the modalities of recurrence within the liver in HCC, 3) and is known to occur more frequently than extrahepatic metastasis. It has been generally accepted that intrahepatic metastasis, as well as venous invasion and primary tumor size, are important risk factors for intrahepatic recurrence of HCC.2, 4-6) Therefore, there is a need for biological and therapeutic studies of intrahepatic metastasis of HCC. To do this, animal models that can confirm clinical behavior are necessary to clarify the mechanism of intrahepatic metastasis, to evaluate the efficacy of new drugs and to search for new therapies.Several studies have shown that orthotopic implantation of tumor cells into the relevant organ of mice can provide an in vivo model to study the biology and therapy of these cells. 7,8) Indeed, models of orthotopic implantation of tumor cells have been developed for lung cancer, 9) colon cancer, 10) pancreatic cancer 11) and also HCC. 12, 13) However, orthotopic implantation of cell suspensions may induce changes in the nature and biological behavior of the original tumor. 14) Considering these points, Fu et al. 15) have constructed metastasis models of colon cancer produced by orthotopic implantation of histologically intact tumor tissue and they reported th...

Recently, growing epidemiological evidence suggests the importance of psychosocial factors in a wide variety of diseases such as depression, cardiovascular diseases and cancer.1-3) Social isolation, divorce and bereavement are reported to be associated with an increased risk of cancer recurrence, the probability of metastasis and mortality rates for cancer, as well as decreased efficacy of cancer therapy. [4][5][6][7] In contrast, reducing the impact of psychosocial stress through social support, including the presence of a social network or psychosocial intervention, has also been shown to be related to an increase in the survival time and a decrease in the rate of metastasis. 8,9) Experimental investigations into the effects of psychosocial factors on tumor progression in animals may provide useful information of basic values for clinical situations. Social isolation (individual housing) is a model of lack of social interactions among animals, which is relatively comparable with the situation of humans who feel isolated. In rodents, social isolation results in marked behavioral disturbances such as increased aggressiveness, enhanced locomotor activity and reduced pentobarbital-induced sleeping time, 10,11) and physiological disturbances, including high levels of plasma corticosterone, catecholamine and high activity of corticotropin releasing factor (CRF). [12][13][14] Because of its inherent social nature, social isolation is viewed as a natural and convenient model of psychosocial stress, and would be helpful for investigating the modulatory role of psychosocial stress in tumor development. Social isolation stress has been reported to accelerate the development and growth of either transplanted or chemically induced tumors, and to attenuate the response of tumors to chemotherapy. [15][16][17] However, there are also some conflicting reports on the association between tumor development and psychosocial stress in both human and animal studies, because of the variations in stress chronicity, timing of stress and types of tumors tested, etc.18,19) Nevertheless, the strong evidence indicates that the tumor progression can be affected by psychosocial factors relating to grouping and isolation, although the underlying mechanism is still unknown. Despite the advances in diagnostic techniques and therapeutic modalities for malignant tumors including colon cancer, the mortality rate of cancer is still high. 20) Many cancer patients develop recurrent and metastatic cancer even if curative surgery is undergone. Metastasis is a major cause of mortality in cancer. However, to our knowledge, the specific effects of psychosocial stress on tumor recurrence and metastasis have only been marginally studied, in spite of the crucial clinical relevance of these phenomena.We recently found that social isolation stress significantly suppressed the basal cellular immune responses and exacerbated experimental liver metastasis of colon 26-L5 carcinoma cells in male BALB/c mice.21) The immune surveillance functions of effector cells su...