Regulation of Bcr-Abl-induced SAP kinase activity and transformation by the SHPTP1 protein tyrosine phosphatase

The oncogenic Bcr-Abl variant of the c-Abl tyrosine kinase transforms cells by a mechanism dependent on activation of the stress-activated protein kinase (SAPK). Other work has shown that c-Abl interacts with the SHPTP1 protein tyrosine phosphatase in induction of SAPK activity by genotoxic stress. The present studies demonstrate that Bcr-Abl binds constitutively to SHPTP1. We show that Bcr-Abl phosphorylates SHPTP1 on C-terminal Y536 and Y564 sites. The functional significance of the Bcr-Abl/SHPTP1 interaction is supported by the finding that SHPTP1 regulates Bcr-Abl-induced SAPK activity. Importantly, SHPTP1 also decreases Bcr-Abl-dependent transformation of fibroblasts. These findings indicate that SHPTP1 functions as a tumor suppressor in cells transformed by Bcr-Abl.

Regulation of DNA-dependent protein kinase by the Lyn tyrosine kinase

The Src-like protein-tyrosine kinase Lyn is activated by ionizing radiation and certain other DNA-damaging agents, whereas the DNA-dependent protein kinase (DNA-PK), consisting of the catalytic subunits (DNA-PKcs) and Ku DNA-binding components, requires DNA double-stranded breaks for activation. Here we demonstrate that Lyn associates constitutively with DNA-PKcs. The SH3 domain of Lyn interacts directly with DNA-PKcs near a leucine zipper homology domain. We also show that Lyn phosphorylates DNA-PKcs but not Ku in vitro. The interaction between Lyn and DNA-PKcs inhibits DNA-PKcs activity and the ability of DNA-PKcs to form a complex with Ku/DNA. These results support the hypothesis that there are functional interactions between Lyn and DNA-PKcs in the response to DNA damage.

Functional role for the c-Abl tyrosine kinase in meiosis I

The c-Abl tyrosine kinase is activated by ionizing radiation and certain other DNA-damaging agents. The DNA-dependent protein kinase (DNA-PK) and the ataxia telangiectasia mutated (ATM) gene product, effectors in the DNA damage response, contribute to the induction of c-Abl activity. The present study demonstrates that c-Abl is expressed in mouse and rat testes, and predominantly in pachytene spermatocytes of meiosis I. The results also demonstrate that c-Abl interacts directly with meiotic chromosomes. In concert with a requirement for c-Abl at the pachytene stage, we show that, in contrast to wild-type mice, testes from Abl-/- mice exhibit defects in spermatogenesis. These findings provide the first demonstration that c-Abl plays a functional role in meiosis.

Cytochrome c-dependent and -independent induction of apoptosis in multiple myeloma cells

Cytochrome c is a mitochondrial protein that induces apoptosis when accumulated in the cytosol in response to diverse stress inducers. This protein has also been shown to cause apoptosis when added to cell free extracts. In this report, we studied the role of cytochrome c (cyto-c) in dexamethasone (Dex), anti-Fas monoclonal antibody (mAb), and ionizing radiation-induced apoptosis in multiple myeloma cells. The results demonstrate that ionizing radiation-induced apoptosis is associated with an increase in cytosolic cyto-c levels, whereas apoptosis induced by Dex or anti-Fas mAb has no detectable effect on cyto-c release. By contrast, caspase-3 was activated in response to all of these agents. Thus, our findings suggest that Dex or anti-Fas mAb-induced apoptosis is not accompanied by cyto-c release and that there are at least two different pathways leading to activation of caspases and induction of apoptosis in multiple myeloma cells that can be distinguished by accumulation of cytosolic cyto-c.

Trends in diagnosis of stage T1a-b prostate cancer

PURPOSE

Stage T1a-b prostate cancer comprised about 44% of newly diagnosed local prostate cancer cases in the United States before the advent of medical and minimally invasive treatments for symptomatic benign prostatic hyperplasia (BPH) and before the widespread use of prostate specific antigen (PSA) testing in men with BPH. Information about the impact of these advances on detection of T1a-b cancer is not available.

MATERIALS AND METHODS

Prevalence of T1a-b prostate cancer was determined in 1,554 consecutive men who underwent surgical prostatectomy for suspected BPH at a Veterans Affairs Medical Center from 1985 through 1996. Since 1991 a PSA blood test was obtained routinely before surgery and patients with PSA greater than 4.0 ng./ml. usually underwent ultrasound guided prostate biopsy.

RESULTS

The number of T1a-b cancer cases was relatively stable during 1985 to 1990 but declined from 36 in 1990 to 9 in 1996. There were no temporal trends in proportion of prostatectomy patients with T1a-b cancer and the decline in cancer detection paralleled less frequent use of surgical prostatectomy for treatment of BPH. The proportion of prostatectomy patients with T1a-b cancer was similar in 1985 to 1990 and in 1991 to 1996 but the percentage of Gleason 7 to 10 cancers declined from 26 in 1985 to 1990 to 10 in 1991 to 1996 (p < 0.0001). PSA and PSA density of evaluable patients with cancer were significantly greater than in evaluable patients with BPH. Of 105 patients with PSA greater than 4.0 ng./ml. who underwent preoperative prostate biopsy 16 (15%) had T1a-b cancer.

CONCLUSIONS

The less frequent use of surgical prostatectomy at our institution has produced marked decline in detection of T1a-b cancer. If representative of national trends this experience suggests that many men with obstructive voiding symptoms and T1a-b cancer will remain undiagnosed and that periodic monitoring to identify unsuspected cancer is important in men who are treated with medical or minimally invasive therapies for BPH. Decline in detection of T1a-b cancer may also confound the accuracy of projected incidence rates of local prostate cancer in the United States.

Dexamethasone induces apoptosis of multiple myeloma cells in a JNK/SAP kinase independent mechanism

The stress-activated protein kinases (SAPKs), also known as c-Jun amino-terminal kinases (JNKs), are activated in response to diverse stimuli including DNA damage, heat shock, interleukin-1, tumor necrosis factor-alpha and Fas. Although all these inducers cause apoptosis, whether SAPK/JNK activation is required for apoptosis is controversial. In this study, we demonstrate that ionizing radiation (IR) and dexamethasone (Dex) induce apoptosis in multiple myeloma (MM) derived cell lines, as well as in patient cells. IR-induced apoptosis is associated with activation of SAPK/JNK and p38 kinase, in contrast to Dex-induced apoptosis, which is not associated with activation of stress kinases. Moreover, Dex-induced apoptosis is associated with a significant decrease in the activities of mitogen activated protein kinase (MAPK) and p70S6K, whereas IR-treatment does not alter the activity of these kinases. Both IR and Dex induce poly (ADP ribose) polymerase (PARP) cleavage, a signature event of apoptosis. Finally, interleukin-6 (IL-6) inhibits Dex-induced apoptosis, downregulation of MAP and p70S6K growth kinases and PARP cleavage; in contrast, IL-6 does not inhibit IR-induced apoptosis, activation of SAPK/JNK, and PARP cleavage. Taken together, our findings suggest that SAPK/JNK activation is not required for apoptosis in MM cells, and that there are at least two distinct apoptotic signaling pathways: (i) SAPK/JNK-associated, which is induced by IR and unaffected by IL-6; and (ii) SAPK/JNK-independent, which is induced by Dex, associated with downregulation of MAPK and p70S6K and inhibited by IL-6.

Role for Bcl-xL as an inhibitor of cytosolic cytochrome C accumulation in DNA damage-induced apoptosis

Cytochrome C is a mitochondrial protein that induces apoptosis when released into the cytosol or when added to cell-free extracts. Here we show that cells that overexpress the Bcl-2-related protein Bcl-xL fail to accumulate cytosolic cytochrome C or undergo apoptosis in response to genotoxic stress. Coimmunoprecipitation studies demonstrate that Bcl-xL associates with cytochrome C. Cytochrome C binds directly and specifically to Bcl-xL and not to the proapoptotic Bcl-xs protein. The results also demonstrate that Bcl-xs blocks binding of cytochrome C to Bcl-xL. Our findings support a role for Bcl-xL in protecting cells from apoptosis by inhibiting the availability of cytochrome C in the cytosol.

Augmented sympathetic tone alters muscle metabolism with exercise: lack of evidence for functional sympatholysis

It is unclear whether sympathetic tone opposes dilator influences in exercising skeletal muscle. We examined high levels of sympathetic tone, evoked by lower body negative pressure (LBNP, -60 mmHg) on intramuscular pH and phosphocreatine (PCr) levels (31P-nuclear magnetic resonance spectroscopy) during graded rhythmic handgrip (30 contractions/min; approximately 17, 34, 52 and 69% maximal voluntary contraction). Exercise was performed with LBNP and without LBNP (Control). At the end of exercise, LBNP caused lower levels of muscle pH (6.59 +/- 0.09) compared with Control (6.78 +/- 0.05; P < 0.05). PCr recovery, an index of mitochondrial respiration, was less during the recovery phase of the LBNP trial. Exercise mean arterial pressure was not altered by LBNP. The protocols were repeated with measurements of forearm blood flow velocity and deep venous samples (active forearm) of hemoglobin (Hb) saturation, pH, and lactate. With LBNP, mean blood velocity was reduced at rest, during exercise, and during recovery compared with Control (P < 0.05). Also, venous Hb saturation and pH levels during exercise and recovery were lower with LBNP and lactate was higher compared with Control (P < 0.05). We conclude that LBNP enhanced sympathetic tone and reduced oxygen transport. At high workloads, there was a greater reliance on nonoxidative metabolism. In other words, sympatholysis did not occur.

Functional interaction between DNA-PK and c-Abl in response to DNA damage

How DNA damage is converted into intracellular signals that can control cell behaviour is unknown. The c-Abl protein tyrosine kinase is activated by ionizing radiation and certain other DNA-damaging agents, whereas the DNA-dependent protein kinase (DNA-PK), consisting of a serine/threonine kinase and Ku DNA-binding subunits, requires DNA double-strand breaks or other DNA lesions for activation. Here we demonstrate that c-Abl interacts constitutively with DNA-PK. Ionizing radiation stimulates binding of c-Abl to DNA-PK and induces an association of c-Abl with Ku antigen. We show that DNA-PK phosphorylates and activates c-Abl in vitro. Cells deficient in DNA-PK are defective in c-Abl activation induced by ionizing radiation. In a potential feedback mechanism, c-Abl phosphorylates DNA-PK, but not Ku, in vitro. Phosphorylation of DNA-PK by c-Abl inhibits the ability of DNA-PK to form a complex with DNA. We also show that treatment of cells with ionizing radiation results in phosphorylation of DNA-PK that is dependent on c-Abl. Our results support the hypothesis that there are functional interactions between c-Abl and DNA-PK in the response to DNA damage.

An Open Trial of Trimethoprim Alone against Cyclospora Infections

Cyclospora is a coccidian parasite that infects the upper intestine and causes a prolonged illness consisting of fatigue, anorexia, and diarrhea. Untreated infections can last for several weeks.1 Trimethoprim-sulfamethoxazole (co-trimoxazole) was found to be an effective treatment for Cyclospora infections in a 1994 study performed in Nepal.2 However, people with known allergies to sulfa drugs cannot take co-trimoxazole. A number of antibiotics have been tried against Cyclospora infections without success, including norfloxacin, tinidazole, diloxanide furoate, and quinacrine hydrochloride. Azithromycin was not successful in a small open trial in 1993.3 Trimethoprim is not chemically related to sulfa, and allergy to co-trimoxazole is usually attributed to the sulfamethoxazole component. In order to find a treatment for people infected with Cyclospora who are allergic to sulfa drugs, we undertook an open trial of trimethoprim alone, in a dose of 200 mg twice a day for 7 days.

Proteolytic activation of protein kinase C delta by an ICE/CED 3-like protease induces characteristics of apoptosis

Recent studies have shown that protein kinase C (PKC) delta is proteolytically activated at the onset of apoptosis induced by DNA-damaging agents, tumor necrosis factor, and anti-Fas antibody. However, the relationship of PKC delta cleavage to induction of apoptosis is unknown. The present studies demonstrate that full-length PKC delta is cleaved at DMQD330N to a catalytically active fragment by the cysteine protease CPP32. The results also demonstrate that overexpression of the catalytic kinase fragment in cells is associated with chromatin condensation, nuclear fragmentation, induction of sub-G1 phase DNA and lethality. By contrast, overexpression of full-length PKC delta or a kinase inactive PKC delta fragment had no detectable effect. The findings suggest that proteolytic activation of PKC delta by a CPP32-like protease contributes to phenotypic changes associated with apoptosis.

Activation of p38 mitogen-activated protein kinase by c-Abl-dependent and -independent mechanisms

The p38 mitogen-activated protein (MAP) kinase defines a subgroup of the mammalian MAP kinases that are induced in response to lipopolysaccharide, hyperosmolarity, and interleukin 1. p38 MAP kinase appears to play a role in regulating inflammatory responses, including cytokine secretion and apoptosis. Here we show that diverse classes of DNA-damaging agents such as cisplatinum, 1-beta-D-arabinofuranosylcytosine, UV light, ionizing radiation, and methyl methanesulfonate activate p38 MAP kinase. We also demonstrate that cells deficient in c-Abl fail to activate p38 MAP kinase after treatment with cisplatinum and 1-beta-D-arabinofuranosylcytosine but not after exposure to UV and methyl methanesulfonate. Reconstitution of c-Abl in the Abl-/- cells restores that response. Similar results were obtained for induction of the Jun-NH2-kinase/stress-activated protein kinase. These findings indicate that p38 MAP and Jun-NH2-kinase/stress-activated protein kinases are differentially regulated in response to different classes of DNA-damaging agents.

The stress response to ionizing radiation involoves c-Abl-dependent phosphorylation of SHPTP1

c-Abl is a nonreceptor tyrosine kinase that is activated by certain DNA-damaging agents. The present studies demonstrate that nuclear c-Abl binds constitutively to the protein tyrosine phosphatase SHPTP1. Treatment with ionizing radiation is associated with c-Abl-dependent tyrosine phosphorylation of SHPTP1. The results demonstrate that the SH3 domain of c-Abl interacts with a WPDHGVPSEP motif (residues 417-426) in the catalytic domain of SHPTP1 and that c-Abl phosphorylates C terminal Y536 and Y564 sites. The functional significance of the c-Abl-SHPTP1 interaction is supported by the demonstration that, like c-Abl, SHPTP1 regulates the induction of Jun kinase activity following DNA damage. These findings indicate that SHPTP1 is involved in the response to genotoxic stress through a c-Abl-dependent mechanism.

c-Abl activation regulates induction of the SEK1/stress-activated protein kinase pathway in the cellular response to 1-beta-D-arabinofuranosylcytosine

Previous work has shown that treatment of cells with the antimetabolite 1-beta-D-arabinofuranosylcytosine (ara-C) is associated with induction of the c-jun gene. The present studies demonstrate that ara-C activates the c-Abl non-receptor tyrosine kinase. We also demonstrate that activity of the stress-activated protein kinase (SAP kinase/JNK) is increased in ara-C-treated cells. Using cells deficient in c-Abl (Abl-/-) and after introduction of the c-abl gene, we show that ara-C-induced c-Abl activity is necessary for the stimulation of SAP kinase. Other studies using cells transfected with a SEK1 dominant negative demonstrate that ara-C-induced SAP kinase activity is SEK1-dependent. Furthermore, we show that overexpression of truncated c-Abl results in activation of the SEK1/SAP kinase cascade.

Seminal vesicle abscess: a case report and review of literature

Seminal vesicle abscess, a rare urologic entity, is usually diagnosed with computerized tomography (CT) scan. We report a case of seminal vesicle abscess that required a transrectal ultrasonography to confirm the diagnosis. An analysis of 20 cases of seminal vesicle abscess reported in the literature is also reviewed.

Ultrasound guided seminal vesicle biopsies in men with suspected prostate cancer

PURPOSE

The histology of ultrasound guided seminal vesicle biopsies is assessed and the results are correlated with clinical or pathological stage of prostate cancer.

MATERIALS AND METHODS

A total of 517 consecutive men underwent bilateral (515) or unilateral (2) seminal vesicle biopsy during sextant biopsy of the prostate.

RESULTS

Seminal vesicle epithelium and muscularis were identified in 490 of 1,032 biopsy specimens (47%) and smooth muscle consistent with seminal vesicle muscularis was identified in 393 (38%). The seminal vesicle biopsy was positive for cancer in 7 of 123 patients (6%) with with clinical stages T1c and T2 tumors, 27 of 60 (45%) with stages T3 to 4 disease and 9 of 13 (69%) with metastatic cancer. Of 39 patients who underwent radical prostatectomy 1 of 36 (3%) without and 0 of 3 (0%) with seminal vesicle invasion had a positive seminal vesicle biopsy.

CONCLUSIONS

Seminal vesicle epithelium and muscularis or smooth muscle consistent with the seminal vesicle muscularis can be procured in most patients using contemporary ultrasound guided biopsy techniques. However, apparently false-negative seminal vesicle biopsies are not uncommon and seminal vesicle biopsies contribute little to the staging of T1c and T2 tumors.

Association of the DF3/MUC1 breast cancer antigen with Grb2 and the Sos/Ras exchange protein

The DF3/MUC1 mucin-like glycoprotein is aberrantly overexpressed in human breast carcinomas. Although the precise functional role of this protein remains unclear, the cytoplasmic tail contains potential tyrosine phosphorylation sites for binding to Src homology 2 (SH2) domains. In the present studies using human MCF-7 breast cancer cells, we show that tyrosine phosphorylated DF3 directly interacts with the SH2 domain of the adaptor protein Grb2. The findings indicate that a pYTNP site in DF3 is responsible for this interaction. The results also demonstrate that the DF3/Grb2 complex associates with the guanine nucleotide exchange protein Sos. Because Sos binds to the SH3 domains of Grb2 and, thereby, associates with Ras at the cell membrane, formation of a DF3/Grb2/Sos complex supports a role for DF3 in intracellular signaling.

Activation of the c-Abl tyrosine kinase in the stress response to DNA-damaging agents

The product of the c-abl gene is a non-receptor tyrosine kinase that is localized to the nucleus and cytoplasm. The precise function of c-Abl is unknown. Here we show that ionizing radiation activates c-Abl. Similar results were obtained with the alkylating agents cis-platinum and mitomycin C. We also demonstrate that cells deficient in c-Abl fail to activate Jun kinase (JNK/SAP kinase) after ionizing radiation or alkylating agent exposure and that reconstitution of c-Abl in these cells restores that response. In contrast, the stress response to tumour-necrosis factor is stimulated by a c-Abl-independent mechanism. These findings indicate that c-abl is involved in the stress response to DNA-damaging agents.

Prostate specific antigen after gonadal androgen withdrawal and deferred flutamide treatment

PURPOSE

We assess the impact of deferred flutamide treatment on the serum prostate specific antigen (PSA) level in patients with localized or metastatic cancer.

MATERIALS AND METHODS

The study included 45 patients with localized cancer and 50 with metastatic cancer with an increasing (87) or stable (8) PSA level after gonadal androgen withdrawal.

RESULTS

Of 40 evaluable patients with localized cancer and 50 with metastatic cancer 32 (80%) and 27 (54%), respectively, had a PSA decrease of 50% or more of baseline during flutamide treatment (p = 0.014). Among patients with localized cancer actuarial analysis of freedom from PSA elevation during flutamide treatment favored those with a 50% or greater PSA decrease (p = 0.006) but in patients with metastatic cancer the analysis revealed no significant difference.

CONCLUSIONS

The relative density of tumor cells that are dependent on adrenal androgen after gonadal androgen withdrawal may be greater in patients with localized cancer and deferred flutamide treatment may enhance cancer control in those with localized disease.

Prostate specific antigen regression and progression after androgen deprivation for localized and metastatic prostate cancer

To identify prostate specific antigen (PSA) functions of prognostic significance in regard to treatment with androgen deprivation for prostate cancer we analyzed the pretreatment PSA, PSA half-life, PSA nadirs, times to PSA elevation and PSA doubling times in 245 patients with localized and 78 with metastatic disease who were treated with this modality. There was a direct correlation between the pretreatment PSA and the time to PSA elevation in patients with localized cancer (p = 0.000003) but no significant correlation in those with metastatic cancer. The PSA half-life was highly variable and did not correlate with other PSA functions of prognostic significance. Incremental increases in the PSA nadir correlated with the time to PSA elevation in patients with localized and metastatic cancer (p < 0.000001 and p = 0.00009, respectively), and with other parameters of prognostic significance. The median PSA doubling time in 26 patients with localized cancer in whom distant metastases did not develop (7.5 months) was significantly longer than that in 7 in whom new metastases developed (2.5 months) and in 43 with preexisting metastatic cancer (2.5 months) (p < 0.05 and p < 0.0001, respectively). In the 7 patients with localized cancer in whom metastases developed the median of the ratios of the PSA when the metastases were manifest and the pretreatment PSA was 0.14, and in 24 patients with preexisting metastatic cancer the median of the ratios of the antemortem PSA and the pretreatment PSA was 1.2. These data show that PSA synthesis by prostate cancer is reduced after androgen deprivation but that the PSA nadir and PSA doubling time following treatment provide important prognostic information.

Synthesis and in vivo hypoglycemic screening studies on some life essential metal complexes of oral antidiabetic [N-(p-tolylsulphonyl)-N'-n butyl-urea] (tolbutamide)

Present communication deals with the synthesis of complexes of [N-(p-tolylsulphonyl)-N'-n butyl-urea], with certain transition metals viz. Cu(II), Zn(II), Fe(II) and Cd(II). Structures of all the complexes have been established on the basis of their consistent elemental and spectral analysis. Also, it reports their in vivo hypoglycemic screening on albino rats. Out of all the complexes studied, Zn-Tolbutamide complex could be recommended as more potent hypoglycemic agent in lieu of tolbutamide alone.

Placebo-controlled trial of co-trimoxazole for Cyclospora infections among travellers and foreign residents in Nepal

Cyclospora is a coccidian (previously referred to as cyanobacterium-like bodies) that has been implicated in cases of prolonged diarrhoea. The average duration of symptoms is more than three weeks, and no specific treatment has been shown to shorten the illness. A case report suggested that co-trimoxazole may be effective. Expatriate persons with gastrointestinal complaints and cyclospora detected on examination of faeces were recruited from two clinics in Kathmandu, Nepal, between May and August, 1994. Participants were assigned in a randomised, double-blinded manner to receive either cotrimoxazole (160 mg trimethoprim, 800 mg sulphamethoxazole) or placebo tablets twice daily for 7 days. Of 40 patients included in the study, 21 received cotrimoxazole and 19 placebo. There were no significant differences between these two groups in age, sex, time in Nepal, duration or severity of illness, or presence of other enteric pathogens. After 3 days, 71% of patients receiving co-trimoxazole still had cyclospora detected, compared with 100% of patients receiving placebo (p = 0.016). After 7 days, cyclospora was detected in 1 (6%) of 16 patients treated with co-trimoxazole who submitted stool specimens compared with 15 (88%) of 17 patients receiving placebo (p < 0.0001). Eradication of the organism was correlated with clinical improvement. There was no evidence of relapse of infection among treated patients followed for an additional 7 days. Treatment with co-trimoxazole for 7 days was effective in curing cyclospora infection among an expatriate population in Nepal.

Variable histology of anastomotic biopsies with detectable prostate specific antigen after radical prostatectomy

Progressive elevation of the prostate specific antigen (PSA) level after radical prostatectomy for adenocarcinoma is generally considered as irrefutable evidence of recurrent tumor. We assessed the results of 62 biopsies of the vesicourethral anastomosis in 41 men who had 3 or more consecutive PSA levels of 0.4 ng./ml. or greater after radical prostatectomy and no evidence of metastatic disease. The median PSA at the time of the first biopsy was 2.2 ng./ml. (range 0.4 to 50). Histological confirmation of recurrent cancer was established after 1 biopsy procedure in 39% of the patients and after 1 or more biopsy procedures in 59%. Biopsy was positive in 78% of 23 patients with an abnormal digital rectal examination, 40% of 5 with an abnormal transrectal ultrasound only, and 23% of 13 with a normal digital rectal examination and ultrasound. Among the patients with and without biopsy proved tumor recurrence there were no significant differences between the pathological stage or histological grade of the primary tumors, the month after surgery of the first detectable PSA level, the PSA doubling time, the month after surgery of the positive biopsy or the last negative biopsy, and the PSA level at the time of the positive biopsy or the last negative biopsy. In 6 cases benign prostatic tissue only was recovered from 1 or more biopsy specimens. This experience demonstrates that in patients with a detectable PSA after radical prostatectomy recurrent cancer may be difficult to document by biopsy of the vesicourethral anastomosis.