Augmentation of 3‐methylcholanthrene‐induced bioactivation in the human hepatoma cell line HepG2 by the calcium channel blocker nicardipine

(Cancer Sci 2010; 101: 652–657) The abilities of the dihydropyridine calcium channel blocker nicardipine (Nic) to induce cytochrome P450 1 family enzymes (CYP1s) and to enhance the 3‐methylcholanthrene (MC)‐mediated induction of CYP1s and formation of MC‐DNA adduct were examined in the human hepatoma cell line HepG2. The results from real time RT‐PCR analysis demonstrated that Nic could induce CYP1 mRNAs and enhance the MC‐mediated induction of the CYP1 mRNAs. The luciferase‐reporter gene assay using the HepG2‐A10 cell line, which has been previously established for the screening of aryl hydrocarbon receptor (AhR) activators, also indicated the augmentation of MC‐mediated activation of AhR (induction of luciferase) by Nic, although Nic showed limited capacity for the activation of AhR. Furthermore, the results from the Western blot analysis of CYP1s, the enzyme activity assay, and the assay for MC‐DNA adduct formation indicated that Nic could enhance the MC‐mediated induction of CYP1s, especially CYP1A1. Furthermore, the intracellular accumulation level of [³H]MC after treatment of HepG2 cells with [³H]MC significantly increased in the presence of Nic. The present findings demonstrate that Nic can enhance the MC‐mediated induction of CYP1s, especially CYP1A1, and the formation of MC‐DNA adduct in HepG2 cells. Furthermore, the augmentation of the MC‐mediated bioactivation by Nic is demonstrated to occur mainly through an increase in intracellular accumulation of MC.     

A case with breast cancer under the nipple who underwent breast conserving treatment

Although breast conserving treatment (BCT) has become the standard therapy for early breast cancer, breast removal is still recommended for patients with a tumor beneath the nipple or with Paget’s disease. We have employed transposition of a latissimus dorsi myocutaneous (LD-MC) flap after wide local excision of a tumor with the nipple-areola complex. A new nipple-areola complex was reconstructed on the LD-MC flap after breast irradiation. Utilizing reconstructive techniques, BCT will likely become the treatment of choice for more patients with early breast cancer.     

Ganglioglial Differentiation in Medulloblastoma

A case of cerebellar medulloblastoma with clusters of mature ganglion cells and glial cells is described. The patient, a 15 -year -old girl, underwent three operations followed each time by radiation and chemotherapy during the four-year clinical course. Histologically, the ganglion cells were clearly identifiable by their abundant eosino-philic cytoplasm, round nuclei with prominent nucleoli, tigroid granules, and argyrophilic fibrils and axons. Im-munohistochemically, the cells were NSE- and NF positive, and ultrastructurally they contained abundant tubules and filaments, neurosecretory granules and well developed rough endoplasmic reticulum. There were many cells transitional in appearance between primitive cells and mature ganglion cells. The tumor also had many mature yet atypical astrocytes and oligodendrocytes. The exact mechanism of the extensive neuronal and glial maturation of medulloblastoma cells is unclear, but the repetitive surgical interventions, radiation and chemotherapy might have had certain cytostatic effects on rapidly dividing medulloblastoma cells, giving them a chance to mature into postmitotic cells with potential for neuronal and glial differentiation. Acta Pathol Jpn 40: 50–56, 1990.     

PRIMARY MUCIN-PRODUCING ADENOSQUAMOUS CARCINOMA OF THE THYROID GLAND

A rare case of mucin-producing adenosquamous carcinoma of the thyroid gland is reported in a 57-year-old woman. Light microscopically, much of the tumor showed a feature of mucin-producing adenosquamous carcinoma; squamous cells and mucous signet ring cells. In the lower portion of the tumor, a calcified area containing small foci of follicular carcinoma and its squamous cell metaplasia was accompanied. Histochemically, neutral, non-sulphated and sulphated acid mucins were found in the mucous cells, and no thyroglobulin or calcitonin was detected in the tumor cells. Electron microscopically, some tonofibrils and mucin production were observed concomitantly in the tumor cells. These findings suggested the possibility that this mucin-producing adenosquamous carcinoma originated from squamous cell metaplasia of pre-existing follicular carcinoma. ACTA PATHOL. JPN. 37: 1157 -1164, 1987.     

Assessment of statistic analysis in non-radioisotopic local lymph node assay (non-RI-LLNA) with alpha-hexylcinnamic aldehyde as an example

The murine local lymph node assay (LLNA) is used for the identification of chemicals that have the potential to cause skin sensitization. However, it requires specific facility and handling procedures to accommodate a radioisotopic (RI) endpoint. We have developed non-radioisotopic (non-RI) endpoint of LLNA based on BrdU incorporation to avoid a use of RI. Although this alternative method appears viable in principle, it is somewhat less sensitive than the standard assay. In this study, we report investigations to determine the use of statistical analysis to improve the sensitivity of a non-RI LLNA procedure with alpha-hexylcinnamic aldehyde (HCA) in two separate experiments. Consequently, the alternative non-RI method required HCA concentrations of greater than 25% to elicit a positive response based on the criterion for classification as a skin sensitizer in the standard LLNA. Nevertheless, dose responses to HCA in the alternative method were consistent in both experiments and we examined whether the use of an endpoint based upon the statistical significance of induced changes in LNC turnover, rather than an SI of 3 or greater, might provide for additional sensitivity. The results reported here demonstrate that with HCA at least significant responses were, in each of two experiments, recorded following exposure of mice to 25% of HCA. These data suggest that this approach may be more satisfactory-at least when BrdU incorporation is measured. However, this modification of the LLNA is rather less sensitive than the standard method if employing statistical endpoint. Taken together the data reported here suggest that a modified LLNA in which BrdU is used in place of radioisotope incorporation shows some promise, but that in its present form, even with the use of a statistical endpoint, lacks some of the sensitivity of the standard method. The challenge is to develop strategies for further refinement of this approach.     

A possible mechanism for 2,2',4,4',5,5'-hexachlorobiphenyl-mediated decrease in serum thyroxine level in mice

Serum total thyroxine (T₄) level was markedly decreased, without significant increases in the levels of hepatic T₄-UDP-glucuronosyltransferase (T₄-UGT) and serum thyroid-stimulating hormone, 3 days after treatment with 2,2′,4,4′,5,5′-hexachlorobiphenyl (CB153) (100 mg/kg, ip) in both 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-sensitive C57BL/6 and TCDD-resistant DBA/2 mice. Likewise, in either strain of mice, no CB153-mediated changes in the binding levels of [¹²⁵I]T₄ to serum proteins, such as transthyretin, albumin, and thyroxine binding globulin, were observed, while in CB153-pretreated C57BL/6 mice, but not in CB153-pretreated DBA/2 mice, the levels of biliary [¹²⁵I]T₄ and [¹²⁵I]T₄-glucuronide at 90-120 min after injection of [¹²⁵I]T₄ slightly increased, as compared with those in the corresponding control mice. Concerning tissue distribution of [¹²⁵I]T₄, liver-selective increases in the [¹²⁵I]T₄ accumulation by CB153-pretreatment were observed in both C57BL/6 and DBA/2 mice, and the hepatic levels of [¹²⁵I]T₄ in the C57BL/6 and DBA/2 mice became more than 44% and 34% of the [¹²⁵I]T₄ dosed, respectively. The present findings indicated that the CB153-mediated decreases in the level of serum total T₄ in C57BL/6 and DBA/2 mice occur mainly through an increase in the accumulation of T₄ in the liver.