Biomedical subjects

H C Chang

Publications and source records attributed to H C Chang.

257 records · Page 15Linked to original sources

PubMedDate not supplied

Cyclooxygenase-2 level and culture conditions influence NS398-induced apoptosis and caspase activation in lung cancer cells.

Cyclooxygenases (COXs) catalyze the synthesis of prostaglandins (PGs) from arachidonic acid. Overexpression of COX-2 is frequently found in human cancers and is suggested to play an important role in tumorigenesis. Recent studies indicated that COX-2 inhibitors exert potent anti-cancer effects on a number of cancers. Interestingly, some COX-2 inhibitors potently induce apoptosis, while other COX-2 inhibitors primarily induce growth inhibition. Therefore, there is a variability in the effects that different COX-2 inhibitors have on cancer cells. In this study, we demonstrated that induction of apoptosis of high COX-2-expressing A549 lung cancer cells by a specific COX-2 inhibitor NS398 was observed in cells cultured under serum-free condition. However, this drug induced G1 growth arrest rather than apoptosis in A549 cells maintained in 10% serum medium. Conversely, low COX-2-expressing H226 lung cancer cells were resistant to NS398-induced apoptosis under both serum-free and serum-containing conditions. Moreover, our results showed that NS398-induced apoptosis is associated with activation of caspase-3, a cysteine protease that plays a crucial role in the execution phase of apoptosis. These results suggest that the cytotoxic effect of COX-2 inhibitors on cancer cells may be influenced by extracellular environments and the anti-cancer action of these inhibitors in vivo needs careful evaluation. Additionally, a correlation between the level of COX-2 expression and the extent of apoptosis induced by COX-2 inhibitors was found.

Apoptosis↗

PubMedDate not supplied

Identification and characterization of androgen receptor associated coregulators in prostate cancer cells.

The androgen receptor (AR) is a member of the nuclear receptor (NR) superfamily that mediates the effects of androgens on target tissues. Over the last decade, it has become apparent that NRs require accessory factors for optimal activation of target gene expression. Numerous NR coregulators have been identified, with diverse structures and potential mechanisms of coregulation, creating an increasingly complicated picture of NR action. Due to the expanding complexity of the coregulator field, this review will focus on the AR ligand-binding domain (LBD) and N-terminal interacting proteins identified by our lab. The LBD-interacting proteins ARA70, ARA55 and ARA54 were first characterized and ARA70 was found to have a relatively higher specificity for the AR in human prostate cancer DU145 cells. Characterization of the functional relationship between the AR and these coregulators indicated that ARA70 and ARA55 could enhance the androgenic effects of 17beta-estradiol (E2) and hydroxyflutamide (HF), an antiandrogen commonly used in the treatment of prostate cancer. ARA160, an AR N-terminal interacting protein also known as TATA element modulatory factor (TMF), was subsequently shown to cooperate with ARA70 in enhancing AR activity. Another AR N-terminal interacting protein, ARA24, interacted with the poly-Q tract, a region within the N-terminus of the AR linked to Kennedy's disease (X-linked spinal and bulbar muscular atrophy). More recently, our lab has identified ARA267, a SET domain containing protein, and supervillin, an F-actin binding protein, as AR coregulators. Collectively, the data from these studies indicate that these coregulators are necessary for optimal AR transactivation. Interruption of the interaction between AR and these proteins may serve as a new therapeutic target in the treatment of prostate cancer.

Acetyltransferases↗

PubMedDate not supplied

[Schizencephaly: report of one case].

This article presents a 4-year-old boy who suffered from weakness of the right extremities since birth. Physical examination revealed mild mental retardation and right spastic hemiplegia. No seizures were noted. A brain CT scan showed bilateral clefts along Sylvian fissures, more marked on the left side, which communicated with the lateral ventricle. The septum pellucidum was absent. There was an evident squaring of the frontal horns. The CT findings were consistent with the diagnosis of schizencephaly. When a patient with mental retardation and spastic hemiplegia or diplegia fails to show a history of perinatal cerebral insult, the possibility of schizencephaly should be considered. In that case, a brain CT scan is a rapid and accurate diagnostic tool.

Brain↗

PubMedDate not supplied

Expression of estrogen and progesterone receptors in non-small-cell lung cancer: immunohistochemical study.

Estrogen receptor (ER) and progesterone receptor (PgR) have been recognized as being involved in the tumourigenesis of non-small-cell lung cancer (NSCLC). Forty-nine resected NSCLC (39 males and 10 females) were studied immunohistochemically in formalin-fixed, paraffin-embedded sections for ER and PgR. There were 26 squamous cell carcinomas, 22 adenocarcinomas and one adenosquamous carcinoma. 38.8% (19/49)NSCLC had either a positive ER or PgR status of which one was ER+/PgR+, 2 were ER+/PgR- and 16 were ER-/PgR+. There was no statistical difference in hormone receptors status for sex and histological subtypes (p > 0.05). The immunohistochemical assay of formalin-fixed paraffin-embedded sections allows the retrospective analysis of ER and PgR in NSCLC. The ER-/PgR+ status was detected in about one third NSCLC. The discordance between these receptors is suggested to be due to either the presence of functioning variant ER or the constitutive synthesis of PgR independent of estrogen induction in certain ER-/PgR+ NSCLC.

Adenocarcinoma↗

PubMedDate not supplied

Provocation of hypotension and pain during upright tilt table testing in adults with fibromyalgia.

OBJECTIVE: Fibromyalgia is a common but poorly understood problem characterized by widespread pain and chronic fatigue. Because chronic fatigue has been associated with neurally mediated hypotension, we examined the prevalence of abnormal responses to upright tilt table testing in 20 patients with fibromyalgia and 20 healthy controls. METHODS: Each subject completed a symptom questionnaire and underwent a three stage upright tilt table test (stage 1:45 minutes at 70 degrees tilt; stage 2, 15 minutes at 70 degrees tilt with isoproterenol 1-2 micrograms/min; stage 3, 10 minutes at 70 degrees tilt with isoproterenol 3-4 micrograms/min). An abnormal response to upright tilt was defined by syncope or presyncope in association with a drop in systolic blood pressure of at least 25 mm Hg and no associated increase in heart rate. RESULTS: During stage 1 of upright tilt, 12 of 20 fibromyalgia patients (60%), but no controls had an abnormal drop in blood pressure (P < 0.001). Among those with fibromyalgia, all 18 who tolerated upright tilt for more than 10 minutes reported worsening or provocation of their typical widespread fibromyalgia pain during stage 1. In contrast, controls were asymptomatic (P < 0.001). CONCLUSION: These results identify a strong association between fibromyalgia and neurally mediated hypotension. Further studies will be needed to determine whether the autonomic response to upright stress plays a primary role in the pathophysiology of pain and other symptoms in fibromyalgia.

Adult↗