Hypermethylation of the CD44 gene is associated with progression and metastasis of human prostate cancer

BACKGROUND

CD44 is a metastasis suppressor gene for prostate cancer and the down-regulation of CD44 and its variants is associated with the progression of prostate cancer. Also, hypermethylation of the CpG islands of the CD44 gene is closely associated with transcriptional inactivation, resulting in the decreased expression of CD44. To clarify the exact role of methylation status of CpG islands of CD44 gene in the progression and metastasis of prostate cancer, we investigated the methylation status of this gene in primary and metastatic human prostate tumors obtained from surgery or autopsy.

METHODS

We examined 97 samples from 40 Japanese patients with adenocarcinoma of the prostate. Tumor tissues were obtained from radical prostatectomy specimens from eight patients with stage B, 12 patients with stage C and three patients with stage D1 and at autopsy from 17 hormone-refractory metastatic cases, who had initially responded to the therapy and thereafter relapsed. Distant metastatic tissues were also obtained at autopsy (i.e., liver, lung, kidney, mammary gland, and pelvic lymph nodes) from 10 of 17 hormone-refractory cases. We analyzed the hypermethylation status of CD44 promotor region by PCR using genomic DNAs digested with the m(5)C-sensitive restriction enzyme HpaII.

RESULTS

The correlation between the methylation status of CD44 gene and the stage progression of prostate cancer was statistically significant (P = 0.0438). In two of 10 hormone-refractory cases, a comparison of the methylation status of the CD44 gene in metastases to that in primary tumors revealed interfocal heterogeneity of CD44 methylation status.

CONCLUSIONS

These results indicate an important role of CD44 methylation in the progression and metastasis of prostate cancer, although the amount of methylational heterogeneity is substantial among metastatic sites within the same patient.

Prostate adenocarcinoma producing syndrome of inappropriate secretion of antidiuretic hormone

The syndrome of inappropriate secretion of antidiuretic hormone (ADH) was recognized in a 68-year-old man with a poorly differentiated metastatic adenocarcinoma of the prostate. Elevated levels of ADH were found in the tissues of the primary tumor and lymph node metastasis. The patient's clinical course is detailed and the pathophysiology of this syndrome is discussed. To our knowledge, this case is the ninth reported case of syndrome of inappropriate secretion of ADH with adenocarcinoma of the prostate. Antidiuretic hormone activity was proven in only three cases including this case.

Epigenetic regulation of the KAI1 metastasis suppressor gene in human prostate cancer cell lines

Expression of the KAI1 gene, a metastasis-suppressor for prostate cancer, is reduced in all foci of prostatic metastasis. The altered regulatory mechanism is not strongly related to mutations or allelic losses of the KAI1 gene in prostate tumors. Since transcriptional silencing of genes has been found to be caused by epigenetic mechanisms, we have investigated the involvement of this epigenetic regulation of KAI1 expression in prostate cancers. The methylation status of the KAI1 promoter region was examined by restriction-enzyme digestion and sequencing, after amplifying a 331-bp fragment in the GC-rich promoter region from 4 human prostate cancer cell lines treated with bisulfite. The same 4 cell lines were also exposed to various concentrations of the demethylating agent, 5-aza-2'-deoxycytidine (5-AzaC) and / or the histone deacetylase inhibitor, trichostatin A (TSA). To clarify the influence of epigenetic modification on reduced KAI1 mRNA expression in the tumor cells, RT-PCR and northern-blot analyses were performed. Bisulfite-sequencing data showed a few methylated CpG islands in the promoter. RT-PCR analysis of 5-AzaC and / or TSA-treated cells indicated reversal of suppression of KAI1 transcription in two cell lines (PC-3 and DU-145), although the expression could not be detected by northern blots. From these results, it is suggested that epigenetic change is not the main mechanism of KAI1 down-regulation, though there remains a possibility that methylation in a more upstream region might be associated with this regulation.

A novel homologue of the TIAP/m-survivin gene

The inhibitor of apoptosis (IAP) proteins comprise a highly conserved gene family that prevents cell death in response to a variety of stimuli. TIAP/m-survivin, a murine homologue of human Survivin, is a member of the IAP family. TIAP/m-survivin has one baculovirus IAP repeat (BIR) and lacks a C-terminal RING finger motif. Here we identified the genomic DNA region (TIAP-2) that is homologous to the TIAP/m-survivin gene by a low stringency genomic DNA hybridization. The region is on the chromomsome 9 which is distinct from that (chromosome 11) of the TIAP/m-survivin gene, and contains DNA sequence similar to a part of the BIR and the 3' side of the TIAP/m-survivin gene and the sequence homology between them is 92%. Expression of TIAP-2 mRNA was detected in various murine tissues by RT-PCR. Although expression of TIAP/m-survivin mRNA is upregulated in synchronized cells at S to G2/M phase of the cell cycle, expression of TIAP-2 mRNA was constant in the cell cycle, suggesting the different role of TIAP-2 from that of TIAP/m-survivin.

Epigenetic regulation of androgen receptor gene expression in human prostate cancers

Epigenetic mechanisms including DNA methylation and histone deacetylation are thought to play important roles in gene transcriptional inactivation. Heterogenous expression of androgen receptor (AR), which appears to be related to variable responses to endocrine therapy in prostate cancer (PCa) may also be due to epigenetic factors. The methylation status of the 5' CpG island of the AR in 3 prostate cancer cell lines and 10 primary and 14 hormone-refractory PCa samples was determined using the bisulfite PCR methods. In DU145, CpG-rich regions of the AR were hypermethylated. By an immunohistochemical analysis, only one PCa sample had no AR expression, the others being heterogenous. Bisulfite sequencing and methylation-specific PCR analysis showed aberrant methylation of AR 5'-regulatory region in 20% of 10 primary and 28% of 14 hormone-refractory PCa samples. To clarify the effect of epigenetic regulation on AR expression, we treated three prostate cancer cell lines with a demethylating agent, 5-aza-2'-deoxycytidine (azaC), and a histone deacetylase inhibitor, Trichostatin A (TSA). In DU145, re-expression of AR mRNA was detected after treatment with azaC and/or TSA. Our results suggest that epigenetic regulations including CpG methylation and histone acetylation may play important roles in the regulation of the AR.

Are alpha-blockers involved in lower urinary tract dysfunction in multiple system atrophy? A comparison of prazosin and moxisylyte

Lower urinary tract dysfunction is a major cause of morbidity in patients with multiple system atrophy (MSA). alpha1-Adrenergic receptors are present in the proximal urethra where impaired relaxation may be responsible for voiding difficulty and a large amount of residual urine. An open study was designed to evaluate whether the blockade of these receptors by prazosin (a nonselective alpha1 blocker) and moxisylyte (an alpha1A-selective blocker) would improve bladder emptying in patients with MSA. Post-micturition residual volumes and clinical symptoms of 49 patients with MSA were evaluated at trial entry and after 4 weeks (prazosin; n=21 and moxisylyte; n=28). The respective means for the prazosin and moxisylyte groups were 38.1% and 35.2% reductions in residual urine volume (P<0.05), and there was lessening of urinary symptoms. Side effects due to orthostatic hypotension were seen in 23.8% of the prazosin group but in only 10.7% of the moxisylyte group. These effects were common in patients with postural hypotension of more than -30 mmHg at trial entry (P<0.05). Modulation of alpha1-receptors may function in the management of lower urinary tract dysfunction in MSA.

[Penile carcinoma with humoral hypercalcemia of malignancy (HHM): a case report]

A 57-year-old male, with 1.5 cm tumor in his prepuce, was admitted to our institute in Feb. 1990. Circumcision and inguinal lymph node dissection was performed under the diagnosis of T1 disease of penile carcinoma. Pathological evaluation revealed well-differentiated squamous cell carcinoma (SCC). In April 1996, the patient revealed recurrence of the disease in the right inguinal lymph nodes and the lower abdomen, that was diagnosed to be poorly differentiated SCC. Laboratory findings showed elevation of serum calcium, parathyroid hormone-related protein (PTHrP) levels. Immunohistochemical staining confirmed production of PTHrP in the tumor tissue. This is the first case report of penile carcinoma that caused humoral hypercalcemia of malignancy in Japan.

Effects of thyroid hormones on apoptotic cell death of human lymphocytes

Apoptosis plays a critical role in the development and homeostasis of tissues, especially those with high cell turnover such as the lymphoid system. We have examined the effects of thyroid hormones, TSH and TRH, on apoptosis of human T lymphocytes. We found that T lymphocytes cultured with T3 and T4, but not TSH nor TRH, in vitro showed enhanced apoptosis, evidenced by DNA ladder formation and characteristic morphological changes. In addition, prolonged cultivation with thyroid hormones of the lymphocytes further enhanced the extent of apoptosis. We also found that treatment with thyroid hormones of T lymphocytes induced reduction of mitochondrial transmembrane potential (delta psi) and production of reactive oxygen species, both of which are intimately associated with apoptotic cell death. In addition, cellular expression of antiapoptotic Bcl-2 protein was clearly reduced by the treatment of lymphocytes with thyroid hormones in vitro. Thus, T lymphocytes treated with thyroid hormones accompany reduction of Bcl-2 protein expression, production of reactive oxygen species, and reduction of mitochondrial delta psi, resulting in apoptotic lymphocyte death. Moreover, we found that lymphocytes in patients with Graves' disease showed enhanced apoptosis compared with those in normal individuals. These results suggest that thyroid hormones have the potential to induce apoptotic cell death of human lymphocytes in vivo and in vitro.

[Free/total ratio of prostate-specific antigen (PSA) for prostate cancer detection in patients with gray zone PSA level]

Thirty seven patients complaining of voiding disturbance who showed gray zone total prostate-specific antigen (t-PSA) level (upper limit of normal approximately 10 ng/ml) but did not reveal apparent cancerous findings in the prostate were examined for free PSA (f-PSA) and prostate volume. According to histological diagnosis, 9 were cancer cases and the other 28 were non-cancer cases. The free/total (F/T) ratio was 0.10 and 0.16 in the cancer and non-cancer groups, respectively (t-PSA; DPC kit, p = 0.03). The t-PSA (DPC and Dinabott kits), f-PSA and PSA density alone did not distinguish these two groups. For diagnosis of cancer, the ratio seemed to be F/T, the most reliable followed by PSA density and t-PSA. When using a 13% F/T, the sensitivity and specificity for cancer detection were 88.9 and 70.8%, respectively. t-PSA measured with the Dinabott kit, showed a similar tendency except that the F/T ratio showed a slight variation. Prostate volume and patient age influenced the F/T slightly, but these factors may not impair the usefulness of F/T.

A case of pseudo-Bartter's syndrome associated with hypergastrinemia, thrombocytosis and increased serum thyroxine-binding globulin

A housewife, 40 years of age, was admitted with dysesthesia of the extremities, muscle weakness, and attacks of adynamia and thirst. She had been taking a laxative for more than 20 years. On physical examination, blood pressure was 94/56 mmHg. Laboratory tests revealed thrombocytosis, low serum K and marked increases in both plasma renin activity and serum aldosterone. Serum TBG was increased. Serum gastrin was also markedly increased and could not be enhanced by exogenous secretin. Both angiotensin 11 loading test and noradrenalin loading test failed to increase blood pressure. Ammonium chloride loading to examine the disturbance of urinary acidification was abnormal in the short term test and borderline in the long term test. Following a diagnosis of pseudo-Bartter's syndrome induced by long term intake of laxative and repeated diarrhea, the administration of laxative was interrupted and potassium, indomethacin and spironolactone were administered. However, serum K remained low. Hypergastrinemia, thrombocytosis and a high serum TBG level also persisted, the causes of which remain unknown. This is the first reported case of pseudo-Bartter's syndrome associated with hypergastrinemia, thrombocytosis and increased serum TBG.

[Measurement of thyroidal iodine concentration by in vivo x-ray fluorescent analysis, with special reference to clinical usefulness of the method]

With the purpose of evaluating the clinical usefulness of measuring thyroidal iodine concentrations and contents, a simple apparatus was designed and constructed for in vivo x-ray fluorescent analysis. The apparatus consists of an Am-241 exciting source(300 mCi) and pure Ge detector(50 mm2 X 5 mm) for measuring K alpha fluorescent x-rays(28.3 and 28.6 KeV) emitted from exited iodine. A diversing collimator was so designed that most of one lobe of the thyroid is within the field of view. Counting was usually continued for 4--5 minutes on each lobe to obtain the sensitivity of 0.2 mg/g allowing 30% coefficient of variation. Iodine concentrations measured in 34 resected normal thyroids at autopsy ranged from 0.19--1.34 mg/g with a mean of 0.53 mg/g(male 0.48 +/- 0.19 mg/g, female 0.60 +/- 0.32 mg/g m. +/- 1.s.d.). The results correlated well with the measurement of the same thyroids by activation analysis(r = 0.93). In vivo measurement was performed on healthy volunteers including 16 males and 14 females. Iodine concentrations measured on each lobe of the thyroid revealed 0.40 +/- 0.24 mg/g for males and 0.67 +/- 0.29 mg/g for females. Eighty-four measurements were performed on 80 patients with various thyroidal diseases. Iodine concentrations were low in chronic thyroiditis(0.06 +/- 0.13 mg/g) and sub-acute thyroiditis(0.28 +/- 0.12 mg/g). Most patients with Graves' disease showed normal or low iodine concentrations (0.47 +/- 0.29 mg/g) regardless of status of treatments (pre-, under- or posttreatment) or thyroidal function. Twenty-one measurements were performed on 21 patients with nodular goiter. Nodule/Gland ratio of I-127 concentration was 0.78 +/- 0.47 in 17 patients with cold nodule, and it ranged from 1.2--1.9 in 4 patients with hot nodule.

Partial isolation and characterization of bromosulphosphthalein-binding protein from rat liver plasma membranes

Digestion of liver plasma membranes with trypsin and chymotrypsin prevented specific binding of 35-S or 131-I-bromosulphophthalein (BSP) to these membranes, in contrast concomitant appearance of BSP binding protein was observed in a high-speed (100,000 x g. 1 hr) supernatant of the extracts. On the other hand, BSP binding capacity of receptors was hardly destroyed by digestion with high concentration of phospholipase A, C. Gel filtration experiments on a column of Sephadex indicated that specific BSP binding to a protein in the high-speed supernatant was observed and this protein contained at least sialic acid and pentose suggesting a fragment of glycoprotein. In addition this molecular size was far smaller than 23,000, calibrated with bovine trypsin. Competitive inhibition was also observed between 131-I-BSP and BSP on a specific protein by gel filtration, while cholic acid did not affect its capacity to bind 131I-BSP. These results suggest that the specific protein on the liver plasma membrane is involved in the transport of organic anions across hepatocyte surface membranes.

Quantitative in vivo measurement of thyroidal iodine content by static x-ray fluorescent technique: some preliminary clinical observations

A static x-ray fluorescent technique utilizing an 241Am source of low activity and a wide view diverging collimator which allows in vivo determination of the concentration and total content of iodine in the thyroid is described. Determinations of normal thyroidal iodine concentration and total iodine content were as follows: 0.40 mg/g and 10.6 mg for 16 men, and 0.67 mg/g and 17.6 mg for 14 women. This fluorescent system has been applied to 70 patients to date. Thyroidal iodine concentrations in patients with Graves' disease were approximately equal to those in healthy suspects, and little change was observed among the concentrations in patients before, during, or after treatment. In most of the patients with chronic or subacute thyroiditis, concentrations levels were lower.