N-ethyl-N-nitrosourea (ENU) is a potent mutagen in a mouse model by inducing point mutation in a random manner and, in particular, causing heritable base substitutions in spermatogonia. In this study, systematic development of phenotype-driven mutant mice with large scale was carried out by using ENU. Nine-week-old male mice of C57BL/6J received intraperitoneal injection at three times with 100 mg/kg of ENU at weekly intervals for three weeks. After injections with ENU, the changes of body weight, fatality, recovery of fertile period, and breeding record were measured in these mice. Body weight lost as a result of ENU treatments was reversed after the last ENU injection. Live fertile male mice recovered from infertility from 104 to 165 days after ENU treatments were mated with C57BL/6J female mice for generation of G1 offspring. An average birth rate was 5.9 mice from 1 pair of paternal and maternal mice. All of 231 G1 offspring mice were analyzed by modified-SHIRPA with standard procedure at nine weeks of age. Among G1 mice, 166 mice were identified as mutagenic phenotypes in 20 test items. The changes in mutagenic phenotypes after ENU treatments, for instance, pattern in the region with a different color, touch escape, changes in head morphology, pupil, and teeth, and negative geotaxis etc., were found in these mice. Taken together, these results indicate that ENU may be a trans-generational mutagen in C57BL/6J mice.

Cancer is the result of damage to the genetic system, i.e., dysfunction of the DNA repair system, resulting in dysregulated expression of various molecules, leading to cancer formation, migration, and invasion. In cancer progression, several proteases play a critical role in metastasis; however, their biological mechanism in cancer metastasis is not clearly understood. Among these proteases, cathepsins are a family of lysosomal proteases found in most animal cells. Cathepsins have an important role in protein turnover of mammalian, and are classified into 15 types based on their structure as serine (cathepsin A and G), aspartic (cathepsin D and E), and cysteine cathepsins (cathepsin B, C, F, H, K, L, O, S, V, X, and W). Cysteine cathepsins appear to accelerate the progression of human and rodent cancers, which can be a biomarker of the potency of malignancy or metastasis in mammalian. Overexpression of cyteine cathepsins causes the activation of angiogenesis promoting factor, whereas their downregulation reduces the angiogenesis of cancer progression. Under physiological conditions, cysteine cathepsins are essential in inflammation, infection, and cancer development. Activity of cysteine proteases, i.e., cathepsin B, is required for cancer progression or metastasis. Elevation of cysteine cathepsin is associated with cancer metastasis, angiogenesis, and immunity. Therefore, in this review, we suggest that cysteine cathepsin may be an anticancer target of strong clinical interest, although the exact mechanism of cathepsins in cancer metastasis is under investigation.

Endocrine disrupting chemicals (EDCs) have detrimental effects on human health. Among these EDCs, bisphenol A (BPA) binds to estrogen receptors (ERs) to stimulate estrogen-mediated responses. BPA is assumed to disrupt the reproductive and developmental system of humans. In addition, BPA has recently been suspected as a risk of carcinogenesis. Because BPA can cause abnormal estrogen-mediated response in the organism, exposure to BPA may stimulate growth of estrogen-dependent breast cancers in human. In breast cancer, cyclin E and cyclin-dependent kinase inhibitor p27 are important in G1/S phase transition during cell cycle progression. In this study, using an MTT assay, we investigated the effect of BPA on proliferation of MCF-7 breast cancer cells in vitro. In addition, we also analyzed the transcriptional levels of cyclin E and p27 following treatment with BPA using semi-quantitative RT-PCR. As a result, treatment with BPA resulted in significant induction of breast cancer cell growth, compared to a vehicle. BPA caused alterations of cyclin E and p27 mRNA expression. Expression of cyclin E was increased by BPA, while p27 was decreased at 24 h after treatment with BPA in MCF-7 breast cancer cells. Taken together, these collective results suggest that exposure to BPA induced breast cancer cell proliferation with deregulation of the cell cycle. A further study is required in order to determine the effects of BPA on the carcinogenic process in in vivo models.

Epithelial ovarian tumors appear to arise from the ovarian surface epithelium (OSE), a simple squamous-to-cuboidal mesothelium covering the ovary. Ovarian tumorigenesis is the most frequent cause of cancer death in gynecological malignancies; however the exact mechanism of this disease is not well known. A theory of repeated ovulation which contributes to neoplastic transformation of OSE has been proposed, and the process of healing ruptured OSE may contribute to the disease. Therefore, it can be assumed that endocrine and autocrine factors may have an influence on ovarian carcinogenesis in women. Thus, in this review, we suggest that these endocrine and autocrine factors may play a role in ovarian tumorigenesis in regulation of growth-stimulation or -inhibition and/or apoptosis of normal and neoplastic OSE cells via their specific receptors.