Characterization of two different cytoplasmic protein tyrosine kinases from human breast cancer

Primary androgen deprivation therapy for prostate cancer in koreans: a retrospective multicenter study

PURPOSE

To evaluate the characteristics of patients who received primary androgen deprivation therapy (PADT) for prostate cancer and the clinical efficacy of this treatment.

MATERIALS AND METHODS

Two hundred forty patients treated by PADT were reviewed. These patients could not receive definitive therapy owing to old age, patient need, and medical comorbidity. The patients were divided into three groups according to the extent of prostate cancer: localized, locally advanced, and metastatic. Then, prostate-specific antigen (PSA) progression in these groups was analyzed.

RESULTS

The median age of the patients was 73.0 years, and the median pretreatment PSA level was 47.0 ng/mL. Of the patients, 91.7% were treated with combined androgen blockade, and 8.3% were treated with monotherapy. Clinical factors for PSA progression were a PSA nadir and a high clinical stage. Estimated PSA recurrence-free median survival time in each group was 57, 24, and 12 months, respectively. A PSA nadir of >0.2 ng/mL and metastatic stage were independent factors for expecting a poor response to PADT (hazard ratio 4.26, p<0.001; and 2.60, p<0.001).

CONCLUSIONS

Patients with localized or locally advanced prostate cancer who did not receive definitive therapy had lower PSA progression rates than those at metastatic stage during PADT. Further, a PSA nadir of ≤0.2 ng/mL showed better progression-free survival. Therefore, PADT can be another therapeutic option in well-selected patients with localized or locally advanced prostate cancer and PSA change should be checked carefully.

Prognostic assessment of PTK activity in T1-T2, N0-N1, M0 breast cancer: a multicentric retrospective study

Protein tyrosine kinases (PTKs) play a major role in the transduction of intracellular mitogenic signal. PTKs are also involved in the process of cellular transformation. A number of studies have reported increased PTK activities in cytosolic fractions from human breast carcinoma. However, the possible pronostic value of these activities is difficult to establish from these studies, mostly conducted on limited numbers of patients. In order to clear up the issue, we have investigated a large series of patients with a long follow-up, using a retrospective multicentric study (894 breast cancers T1-T2, N0-N1, M0; median follow-up: 67 months). PTKs were measured using a radioenzymatic assay as described in our previously report. We confirmed the already observed correlation between PTK activities and Scarff-Bloom grading (p < 10(-5)), negative estrogen receptor (ER), and progesterone receptor (PR) status. By contrast, we found in this study a correlation between PTK values and clinical nodal status (p = 0.00027) not showed in our precedent analysis. In Cox multivariate analysis, PTK activity does not emerge as a significant pronostic parameter. On the other hand, tumor PTK activity assay may prove of great interest in clinical research using newly developed tyrosine kinase inhibitors in order to assess their biological impact and eventually to predict the responsiveness to these new therapeutic agents.

Deregulation of the cytoplasmic tyrosine kinase cSrc in the absence of a truncating mutation at codon 531 in human bladder carcinoma

The involvement of the cytoplasmic tyrosine kinase cSrc was investigated in human bladder carcinogenesis. Kinase activity was determined in tissue lysates from bladder transitional cell carcinoma (TCC) relative to normal epithelia. Strong kinase activation was observed at all stages of carcinogenesis with a peak at the stage pT1, where tumor cells disrupt the basement membrane and invade the submucosa. In agreement with a role for cSrc in cell invasion, immunocytochemistry analysis showed a strong staining of invading cells. An increase in cSrc protein level were also found in most tumor samples, however, it did not correlate with an increase in activity (r = 0.44) suggesting that cSrc is deregulated in these tumors. Indeed, high Src activity was affinity-purified from a column (IRSVSSDGHE(p)YIYVDP-Affigel 10) that specifically retains active Src. Enzymatic regulation involves the C-terminus, recently found mutated at codon 531 in a subset of advanced human colon cancers. However, no such mutations were detected in TCC, suggesting the existence of other mechanisms for kinase activation.

Hormonal regulation of focal adhesions in bovine adrenocortical cells: induction of paxillin dephosphorylation by adrenocorticotropic hormone

A study of bovine adrenocortical cell shape on adrenocorticotropic hormone (ACTH) challenge showed that the cells round up and develop arborized processes. This effect was found to be (1) specific for ACTH because angiotensin II and basic fibroblast growth factor have no effect; (2) mediated by a cAMP-dependent pathway because forskolin reproduces the effect of the hormone; (3) inhibited by sodium orthovanadate, a phosphotyrosine phosphatase inhibitor, but unchanged by okadaic acid, a serine/threonine phosphatase inhibitor; and (4) correlated with a complete loss of focal adhesions. Biochemical studies of the focal-adhesion-associated proteins showed that pp125fak, vinculin (110 kDa) and paxillin (70 kDa) were detected in the Triton X-100-insoluble fraction from adrenocortical cells. During cell adhesion on fibronectin as substratum, two major phosphotyrosine-containing proteins of molecular masses 125 and 68 kDa were immunodetected in the same fraction. A dramatic decrease in the extent of tyrosine phosphorylation of these proteins was observed within 60 min after treatment with ACTH. No change in pp125fak tyrosine phosphorylation nor in Src activity was detected. In contrast, paxillin was found to be tyrosine-dephosphorylated in a time-dependent manner in ACTH-treated cells. Sodium orthovanadate completely prevented the effect of ACTH. These observations suggest a possible role for phosphotyrosine phosphatases in hormone-dependent cellular regulatory processes.