Id3 induces a caspase-3- and -9-dependent apoptosis and mediates UVB sensitization of HPV16 E6/7 immortalized human keratinocytes.

Inhibitor of differentiation/DNA binding (Id) proteins comprise a class of helix-loop-helix transcription factors involved in proliferation, differentiation, apoptosis, and carcinogenesis. We have shown that while Id2 is induced by UVB in primary keratinocytes, Id3 is upregulated only in immortalized cells. We have now determined that the consequences of ectopic expression of Id3 protein are strikingly different between immortalized and primary keratinocytes. Overexpression of Id3 induces a significant increase in apoptotic cells as revealed by Annexin V positivity as well as proteolytic processing of caspase-3 in immortalized, but not in primary keratinocytes. Id3-green fluorescent protein (GFP)-positive cells exhibited a fivefold increase in apoptotic nuclear fragmentation compared to Id3-GFP-negative cells. These apoptotic responses were accompanied by activation of caspase-3, as shown by immunocytochemical staining with antibodies to active caspase-3. Immunostaining with antibodies to the active form of caspase-9 as well as to the active form of Bax further revealed that induction of apoptosis in Id3-overexpressing keratinocytes occurred via a mitochondrial-caspase-9-mediated pathway. Coexpression of dominant-negative caspase-9 with Id3 significantly suppressed apoptotic nuclear fragmentation, indicating that caspase-9 activation is essential for Id3-induced cell death. This response was also markedly attenuated by coexpression with the Bax antagonist antiapoptotic protein Bcl2, confirming a role for Bax activation in this apoptotic response. Id3-induced Bax activation may result from increased expression of Bax protein. Furthermore, reduction of Id3 expression by small interfering RNAs abrogated the UVB-induced proteolytic activation of caspase-3 in these cells. These data together suggest that UVB-induced apoptosis of immortalized keratinocytes is at least in part due to Id3 upregulation in these cells.

Inhibition of poly(ADP-ribose) polymerase activity is insufficient to induce tetraploidy.

Poly(ADP-ribose) polymerase (PARP) knockout mice are resistant to murine models of human diseases such as cerebral and myocardial ischemia, traumatic brain injury, diabetes, Parkinsonism, endotoxic shock and arthritis, implicating PARP in the pathogenesis of these diseases. Potent selective PARP inhibitors are therefore being evaluated as novel therapeutic agents in the treatment of these diseases. Inhibition or depletion of PARP, however, increases genomic instability in cells exposed to genotoxic agents. We recently demonstrated the presence of a genomically unstable tetraploid population in PARP(-/-) fibroblasts and its loss after stable transfection with PARP cDNA. To elucidate whether the genomic instability is attributable to PARP deficiency or lack of PARP activity, we investigated the effects of PARP inhibition on development of tetraploidy. Immortalized wild-type and PARP(-/-) fibroblasts were exposed for 3 weeks to 20 microM GPI 6150 (1,11b-dihydro-[2H:]benzopyrano[4,3,2-de]isoquinolin-3-one), a novel small molecule specific competitive inhibitor of PARP (K(i) = 60 nM) and one of the most potent PARP inhibitors to date (IC(50) = 0.15 microM). Although GPI 6150 initially decreased cell growth in wild-type cells, there was no effect on cell growth or viability after 24 h. GPI 6150 inhibited endogenous PARP activity in wild-type cells by approximately 91%, to about the residual levels in PARP(-/-) cells. Flow cytometric analysis of unsynchronized wild-type cells exposed for 3 weeks to GPI 6150 did not induce the development of tetraploidy, suggesting that, aside from its catalytic function, PARP may play other essential roles in the maintenance of genomic stability.

Poly(ADP-ribosyl)ation of p53 during apoptosis in human osteosarcoma cells.

Spontaneous apoptosis in human osteosarcoma cells was observed to be associated with a marked increase in the intracellular abundance of p53. Immunoprecipitation and immunoblot analysis revealed that, together with a variety of other nuclear proteins, p53 undergoes extensive poly(ADP-ribosyl)ation early during the apoptotic program in these cells. Subsequent degradation of poly(ADP-ribose) (PAR), attached to p53 presumably by PAR glycohydrolase, the only reported enzyme to degrade PAR, was apparent concomitant with the onset of proteolytic processing and activation of caspase-3, caspase-3-mediated cleavage of poly(ADP-ribose) polymerase (PARP), and internucleosomal DNA fragmentation during the later stages of cell death. The decrease in PAR covalently bound to p53 also coincided with the marked induction of expression of the p53-responsive genes bax and Fas. These results suggest that poly(ADP-ribosyl)ation may play a role in the regulation of p53 function and implies a regulatory role for PARP and/or PAR early in apoptosis.

Induction of apoptosis in proliferating human endothelial cells by the tumor-specific antiangiogenesis agent combretastatin A-4.

The antiangiogenic, tubulin-binding drug combretastatin A-4 exhibits a selective toxicity for proliferating endothelial cells in vitro and induces vascular shutdown in tumor models in vivo. The mechanism of combretastatin A-4 cytotoxicity has now been investigated with cultured proliferating human umbilical vein endothelial cells by examining various markers of apoptosis. Incubation of cells with 0.1 mM combretastatin A-4 induced the conversion (first detected after 6 h) of the CPP32 proenzyme to active caspase-3, a cysteine protease that plays an important role in apoptosis in many cell types; the drug also increased caspase-3 activity. Another early event observed was the binding of annexin V to 50% of the cells 8 h after drug treatment. Internucleosomal DNA fragmentation, another hallmark of apoptosis, was detected in cells incubated with 0.1 mM combretastatin A-4 for 24 h. Staining with Hoechst 33258 revealed that about 75% of cells exhibited a nuclear morphology characteristic of apoptosis after incubation with drug for 24 h. Incubation of cells for up to 8 h with combretastatin A-4 did not induce the release of lactate dehydrogenase or increase the uptake of propidium iodide, both indicators of membrane integrity. These results indicate that the selective cytotoxic effect of combretastatin A-4 is mediated by the induction of apoptosis rather than by necrosis and may provide an enhanced clinical strategy in cancer chemotherapy with this new agent.

Poly(ADP-ribose) polymerase upregulates E2F-1 promoter activity and DNA pol alpha expression during early S phase.

E2F-1, a transcription factor implicated in the activation of genes required for S phase such as DNA pol alpha, is regulated by interactions with Rb and by cell-cycle dependent alterations in E2F-1 abundance. We have shown that depletion of poly(ADP-ribose) polymerase (PARP) by antisense RNA expression downregulates pol alpha and E2F-1 expression during early S phase. To examine the role of PARP in the regulation of pol alpha and E2F-1 gene expression, we utilized immortalized mouse fibroblasts derived from wild-type and PARP knockout (PARP-/-) mice as well as PARP-/- cells stably transfected with PARP cDNA [PARP-/-(+PARP)]. After release from serum deprivation, wild-type and PARP-/-(+PARP) cells, but not PARP-/- cells, exhibited a peak of cells in S phase by 16 h and had progressed through the cell cycle by 22 h. Whereas [3H]thymidine incorporation remained negligible in PARP-/- cells, in vivo DNA replication maximized after 18 h in wild-type and PARP-/-(+PARP) cells. To investigate the effect of PARP on E2F-1 promoter activity, a construct containing the E2F-1 gene promoter fused to a luciferase reporter gene was transiently transfected into these cells. E2F-1 promoter activity in control and PARP-/-(+PARP) cells increased eightfold after 9 h, but not in PARP-/- cells. PARP-/- cells did not show the marked induction of E2F-1 expression during early S phase apparent in control and PARP-/-(+PARP) cells. RT - PCR analysis and pol alpha activity assays revealed the presence of pol alpha transcripts and a sixfold increase in activity in both wild-type and PARP-/-(+PARP) cells after 20 h, but not in PARP-/- cells. These results suggest that PARP plays a role in the induction of E2F-1 promoter activity, which then positively regulates both E2F-1 and pol alpha expression, when quiescent cells reenter the cell cycle upon recovery from aphidicolin exposure or removal of serum.

The E7 protein of human papillomavirus type 16 sensitizes primary human keratinocytes to apoptosis.

The 'high risk' human papillomaviruses are associated with the development of anogenital carcinomas and their E6 and E7 genes possess immortalizing and transforming functions in several in vitro culture systems. Recently the E6 gene has also been shown to enhance the apoptosis of human mammary epithelial cells. To determine the apoptotic activity of these oncogenes in the natural host cell, we infected genital keratinocytes with retroviruses expressing either HPV-16 E6, E7, or both the E6 and E7 (E6/7) genes. Apoptosis was quantitated under normal growth conditions or when induced by tumor necrosis factor alpha/cycloheximide or sulfur mustard. In contrast to previous findings with mammary epithelial cells, the E6 gene did not significantly augment either spontaneous or induced apoptosis. E6 also did not suppress apoptosis in normal keratinocytes (despite dramatically reducing their p53 levels), suggesting that p53-independent events mediated this effect. In contrast, E7 increased both spontaneous and induced apoptosis as well as the cellular levels of p53 and p21 protein. Interestingly, co-expression of E6 abrogated E7-facilitated apoptosis by tumor necrosis factor alpha nearly completely, but had only a minor protective effect on sulfur mustard induced apoptosis in these cells, demonstrating at least in part the p53-dependence and -independence of these two apoptotic pathways. Finally, our results indicate that the apoptosis of normal and E7-expressing keratinocytes is differentially affected by E6 expression and that E7, when unaccompanied by E6, sensitizes keratinocytes to apoptosis.

Reduction of fatal complications from combined modality therapy in Hodgkin's disease.

A total of 464 pathologically staged IA through IIIB Hodgkin's disease patients were evaluated for the risk of developing acute nonlymphocytic leukemia, non-Hodgkin's lymphoma, or a fatal infection after treatment with radiation therapy (RT) alone, initial combined radiation therapy and chemotherapy (CMT), or RT with MOPP administered at relapse. Patients received a standard six cycles of MOPP, and additional maintenance chemotherapy was not administered. Patients receiving total nodal irradiation (TNI) and MOPP chemotherapy have an 11.9% actuarial risk of developing a fatal complication at ten years, as compared to a 0.8% risk for lesser field irradiation and MOPP (P = .005). The risk with RT alone is 0.6%. Patients 40 years of age or older have a greater risk for complications. These data report a low risk for fatal complication with CMT when less than TNI is administered and when maintenance chemotherapy is not used.

Stage III Hodgkin's disease: improved survival with combined modality therapy as compared with radiation therapy alone.

This is a retrospective analysis of 120 patients with pathologically stage IIIA and IIIB Hodgkin's disease treated from April 1969 to December 1982. The median follow-up was 108 months. Treatment consisted of radiation therapy (RT) alone in 54 patients and combined radiation therapy and MOPP (nitrogen mustard, vincristine, procarbazine, prednisone) chemotherapy (CMT) in 66 patients. Stage III patients treated with CMT have an improved actuarial 12-year survival as compared with patients treated with RT alone with MOPP reserved for relapse (80% v 64%; P = .026). The 12-year actuarial freedom from first relapse by treatment for stage III patients is 83% and 40%, respectively (P less than .0001). Improved survivals following combined modality therapy are seen for the following subgroups of stage III patients: stage III2, 66% (CMT) v 44% (total nodal irradiation; TNI), P = .04; stage III1, 97% (CMT) v 73% (TNI), P = .05; stage III mixed cellularity or lymphocyte depletion histology, 94% (CMT) v 65% (TNI), P = .007; and stage III extensive splenic involvement, 77% (CMT) v 58% (TNI), P = .02. These survival differences are not seen in patients with nodular sclerosis or lymphocyte predominance histology or in patients with minimal splenic involvement. These data indicate that the initial use of CMT in stage III Hodgkin's disease results in an improved survival as compared with initial treatment with RT with MOPP reserved for relapse. Patients with limited Stage IIIA disease may still be candidates for radiation therapy alone.

Patterns of relapse in large-cell lymphoma patients with bulk disease: implications for the use of adjuvant radiation therapy.

In patients with large-cell lymphoma (LCL) treated with combination chemotherapy, the presence of bulk disease has consistently been associated with a poorer response rate and a shortened survival. The optimal therapy for patients with bulk disease (greater than or equal to 10 cm) will depend on whether treatment failures result from inadequate tumor eradication in prior bulk sites or from distant dissemination. To address this issue, we have evaluated patterns of relapse in patients with bulk disease who relapsed after achieving a complete remission with methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone (M- or m-BACOD). Eighty-one II, III, or IV patients with disease greater than or equal to 10 cm were identified; 45 of the 81 patients achieved a confirmed complete response (CR) and are included in the analysis. The 45 complete responders included 21 patients with localized (stage II) disease and 24 patients with advanced (stage III/IV) disease. Six of the 21 stage II complete responders and three of the 24 stage II/IV complete responders also received adjuvant radiation therapy following completion of M- or m-BACOD. Only one of the 21 patients with stage II disease relapsed, doing so in the site of prior bulk involvement. In contrast, nine of 24 patients with stage III/IV disease relapsed, although no patient failed solely in the site of prior bulk disease. Stage III/IV patients recurred in either a new site (one patient), a new and old site (five), an old non-bulk site (two), or both old non-bulk and bulk sites (one). These results indicate that advanced-stage bulk-disease patients do not consistently relapse in sites of prior bulk disease; therefore, this group of patients is unlikely to benefit from adjuvant radiation therapy administered following completion of combination chemotherapy. Although the low relapse rate and the addition of adjuvant radiation therapy in a subgroup of the stage II bulk-disease patients precludes a definitive analysis, our results further suggest that these patients may be effectively treated with combination chemotherapy alone.

Improved prognosis of diffuse histiocytic and undifferentiated lymphoma by use of high dose methotrexate alternating with standard agents (M-BACOD).

A new combination chemotherapy program (M-BACOD) was administered to 101 patients with advanced diffuse histiocytic and diffuse undifferentiated lymphoma (DHL and DUL). High dose methotrexate (M) 3 g/m2 with leucovorin factor rescue was given on day 14 between cycles of bleomycin (B), adriamycin (A), cyclophosphamide (C), oncovin (O), and dexamethasone (D) administered every 3 weeks for 10 cycles. The complete remission rate (CR) was 72% in all 101 patients or 77% in 95 evaluable patients. The median follow-up is 3 yr 2 mo with one-third of CR patients followed beyond 4 yr. Twenty-six percent of CR patients have relapsed with a projected 5-yr survival rate of 80% (5-yr disease-free rate 65%). The overall survival of all 101 study patients reaches a plateau at 59% projected out to 5 yr. Patients with prior therapy had a significantly lower CR rate than those without prior treatment (p = 0.001); however, no other unfavorable prognostic characteristics could be identified. Relapse in the central nervous system CNS occurred in only 5.4% of CR patients. M-BACOD results in prolonged survival and possible cure in a high proportion of all patients with DHL and DUL.

Improved survival in patients with limited stage IIIA Hodgkin's disease treated with combined radiation therapy and chemotherapy.

PURPOSE: Patients with laparotomy-staged (PS) III 1A Hodgkin's disease confined to the upper abdomen are believed to have a favorable prognosis and require less aggressive treatment than patients with more-extensive stage III disease. We evaluated prognostic factors and outcome in 93 patients with PS III 1A Hodgkin's disease treated either with radiation therapy (RT) alone or combined RT and chemotherapy (combined modality treatment [CMT]) to determine the extent of treatment needed in this subgroup of stage IIIA patients. MATERIALS AND METHODS: We retrospectively reviewed the freedom from relapse (FFR) rate, sites of recurrence, and survival rate of PS III 1A patients selected to receive extended-field irradiation (MPA, n = 27), total-nodal irradiation (TNI, n = 34), and CMT (n = 32) between 1969 and 1987. CMT consisted of six cycles of mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) chemotherapy and MPA. Patients treated with MPA were part of a prospective trial designed to reduce treatment to patients with minimal stage III disease with very favorable characteristics. RESULTS: Histologic subclass and treatment were the only prognostic factors for FFR and survival rates. Patients with nodular sclerosis or lymphocyte predominance histology had significantly higher FFR and survival rates compared to patients with mixed-cellularity (MC) histology. The 10-year actuarial FFR of PSIII 1A patients treated with MPA was only 39%, versus 55% for TNI (P = .02) and 94% for CMT (v MPA, P < .0001; v TNI, P = .006). The patterns of recurrence in patients who received MPA and TNI were significantly different, with MPA patients relapsing more often in untreated pelvic or inguinal nodes, and TNI patients relapsing more often in extranodal sites with or without nodal sites. The 10-year actuarial overall survival rate for patients treated with CMT was 89% versus 78% for MPA (v CMT, P = .09) and 70% for TNI (v CMT, P = .05). CONCLUSION: Patients with PSIII 1A Hodgkin's disease treated with RT have a significantly higher risk of relapse and potentially a poorer survival compared with patients treated with CMT. These findings suggest that CMT should play a greater role in the treatment of this favorable substage of patients. Management with modified chemotherapy and RT in an attempt to reduce long-term treatment-induced complications may be a preferred approach for future trials.

The m-BACOD combination chemotherapy regimen in large-cell lymphoma: analysis of the completed trial and comparison with the M-BACOD regimen.

One hundred thirty-four assessable patients with stage II-IV large-cell lymphoma (LCL) were treated with the combination chemotherapy regimen methotrexate with leucovorin, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone (m-BACOD) between July 1981 and May 1986. The m-BACOD regimen substituted moderate-dose methotrexate (200 mg/m2 x 2) for the high-dose methotrexate used in the preceding M-BACOD regimen; all other drugs were administered as with m-BACOD. Eighty-two patients (61%) in the completed m-BACOD trial achieved a complete response (CR). With a median follow-up of 3.6 years, 62 patients (76%) continue in CR. Predicted survivals of 1, 3, and 5 years for the entire m-BACOD group are 80%, 63%, and 60%, respectively, with a 5-year disease-free survival (DFS) of 74% for the patients who achieve CR. The results obtained with m-BACOD are comparable with those obtained in the preceding M-BACOD trial, which now has a median follow-up of 8.0 years. The reduction in methotrexate dosage in m-BACOD patients was not associated with an increased incidence of CNS relapse. Long-term follow-up of the 215 M/m-BACOD patients indicates that the regimens are not associated with an increased incidence of secondary malignancy. Prolonged follow-up also indicates that advanced-stage patients have a persistent rate of late relapse of about 7.0% per year for years 2 to 5 of their follow-up and that stage II patients have an approximate 2.1% per year rate of late relapse. Application of the previously described prognostic factor model to the 215 M/m-BACOD patients from the completed trials identifies a high-risk group of patients with a CR rate and predicted 5-year survival (38% and 24%, respectively) that are significantly worse than those of the group as a whole (65% and 57%, respectively).

Cyclophosphamide, carmustine, and etoposide with autologous bone marrow transplantation in refractory Hodgkin's disease and non-Hodgkin's lymphoma: a dose-finding study.

Cyclophosphamide, carmustine (BCNU), and etoposide (VP-16) (CBV) is a widely used conditioning regimen in autologous bone marrow transplantation (ABMT) of patients with refractory and relapsed lymphoma. However, the maximum-tolerated dose (MTD) of these agents when used in combination has not been systematically explored. We treated 58 patients (28 with non-Hodgkin's lymphoma [NHL], 30 with Hodgkin's disease [HD]) at seven dose levels of CBV. Doses were cyclophosphamide 4,500 to 7,200 mg/m2, BCNU 450 to 600 g/m2, and VP-16 1,200 to 2,000 mg/m2. The MTD was cyclophosphamide 7,200 mg/m2, BCNU 450 mg/m2, and VP-16 2,000 mg/m2. Six hundred milligrams per square meter of BCNU was associated with five of 18 cases of interstitial pneumonitis versus two of 40 at 450 mg/m2 (P = .02). Treatment-related mortality was 5% at dose levels less than or equal to the MTD and 22% at the highest dose. In this heavily pretreated patient population, most of whom had high volume residual disease, complete responses (CRs) to CBV and ABMT occurred in 25% of assessable patients with NHL and 43% of patients with HD. Thirteen of 28 patients with NHL and 14 of 30 with HD remain free from disease progression with median follow-up of 212 and 215 days, respectively. CBV can be administered with acceptable toxicity over a wide range of doses to patients with refractory and relapsed lymphoma.

Chronic myelomonocytic leukemia transformation in polycythemia vera.

Myelodysplasia is an increasingly recognized complication of polycythemia vera (PCV) which often precedes leukemic transformation. This paper describes two patients with aggressive chronic myelomonocytic leukemia, previously undescribed as a complication of PCV. Both patients presented with rapidly increasing splenomegaly which was resistant to treatment with hydroxyurea and external beam irradiation. Splenectomy precipitated fatal hepatic failure in one patient. The other died shortly after transformation to acute myelomonocytic leukemia (FAB M4 classification). Pathology of the bone marrow, spleen, and liver was remarkable for extensive infiltration by dysplastic myeloid elements. Survival was short, only 4-6 months from diagnosis. The unique characteristics in these patients were: (i) prior history of PCV; (ii) rapidly increasing splenomegaly resistant to standard therapy; (iii) absence of overt marrow fibrosis; (iv) hypercellularity (greater than or equal to 90% cellular) of the bone marrow with dysplasia in the myeloid, erythroid, and megakaryocytic cell lines; (v) peripheral monocytosis greater than 1 x 10(9); and (vi) extensive infiltration of the spleen and liver by dysplastic myeloid cells. In addition, the patient who subsequently developed acute leukemia had been treated with hydroxyurea under the PVSG-08 protocol, providing further evidence of the potential leukemogenic effects of this agent.

Chronic myelomonocytic leukemia.

Thirty adult patients with CMML were evaluated to determine prognostic factors that might have an impact on conversion to acute leukemia and survival. Neither leukocyte count nor monocyte count correlated with survival. The median survival for all 30 cases was 41 months. Patients with less than 5% marrow blasts had a median survival of 60 months but those with 5-20% blasts had only a 9-month median survival.

Bone-marrow imaging in pure red blood cell aplasia.

Bone-marrow scintigraphy with indium chloride in 111 was performed on a patient with pure red blood cell aplasia before and after successful treatment with immunosuppressive drugs. The return of erythroid precursors to the bone marrow was accompanied by a substantial increase in the marrow uptake of 111In. The distribution of 111In in the posttreatment scan was indistinguishable from that of 52Fe. These results indicate that indium chloride in 111 is a useful agent for the delineation of erythroid cellularity within bone marrow.

Variable effect of recombinant human granulocyte-macrophage colony-stimulating factor on bone marrow fibrosis in patients with myelodysplasia.

Eleven patients with myelodysplastic syndrome (MDS) and bone marrow fibrosis were identified out of a group of 15 patients with MDS who received recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) as part of a phase I/II trial. Bone marrow biopsies were obtained before and after one or more courses of GM-CSF at 250 micrograms/m2 administered as a 12-h infusion each day for 14 days. The biopsies were blindly evaluated and reticulin formation and collagen deposition were graded on a scale of 0-4. Fibrosis unequivocally increased in three patients and decreased in three patients. There were equivocal increases in an additional two patients and decreases in one subject. It was unchanged in one subject and unevaluable in one patient. Although patients in whom fibrosis increased tended to have smaller increases in neutrophil and reticulocyte counts on therapy, the difference was not statistically significant. In this small group of patients, it was not possible to determine clinical features that predicted response. Although GM-CSF can lead to partial resolution of marrow fibrosis in some individuals, it can also accelerate its deposition; improvement in granulocyte or reticulocyte count does not preclude increasing marrow fibrosis. Thus, the use of GM-CSF in patients with myelodysplasia with marrow fibrosis must be undertaken with caution.

Natural killer lymphocytes in hairy cell leukemia: presence of phenotypically identifiable cells with defective functional activity.

Eleven patients with hairy cell leukemia (HCL) were studied to determine the number and function of circulating natural killer (NK) lymphocytes in this disorder using a well-defined surface marker of these cells (Mac-1), the fluorescence-activated cell sorter (FACS), and a standard 51Cr release assay to determine cytotoxicity against the K562 cell line. Four of these patients demonstrated normal numbers of phenotypic and morphological (large granular lymphocyte) NK cells in the blood, but these cells showed a severe functional deficiency in their ability to lyse the K562 target. Sorting experiments demonstrated that although all of the NK activity was contained within the phenotypically identifiable NK population, the defect in NK function persisted even when these cells were isolated from other cell populations. Of the remaining seven patients, two had normal numbers and function of NK cells and five showed a marked deficiency of both phenotypic NK cells in the blood and NK function. These data suggest that the marked in vitro functional deficiencies of NK activity that occur in a majority of patients with HCL are sometimes associated with the preservation of phenotypically identifiable NK cells that are qualitatively rather than quantitatively deficient.

Poly(ADP-ribosyl)ation of p53 in vitro and in vivo modulates binding to its DNA consensus sequence.

The tumor-suppressor p53 undergoes extensive poly(ADP-ribosyl)ation early during apoptosis in human osteosarcoma cells, and degradation of poly(ADP-ribose) (PAR) attached to p53 coincides with poly(ADP-ribose)polymerase-1, (PARP-1) cleavage, and expression of p53 target genes. The mechanism by which poly(ADP-ribosyl)ation may regulate p53 function has now been investigated. Purified wild-type PARP-1 catalyzed the poly(ADP-ribosyl) of full-length p53 in vitro. In gel supershift assays, poly(ADP-ribosyl)ation suppressed p53 binding to its DNA consensus sequence; however, when p53 remained unmodified in the presence of inactive mutant PARP-1, it retained sequence-specific DNA binding activity. Poly(ADP-ribosyl)ation of p53 by PARP-1 during early apoptosis in osteosarcoma cells also inhibited p53 interaction with its DNA consensus sequence; thus, poly(ADP-ribosyl)ation may represent a novel means for regulating transcriptional activation by p53 in vivo.

Acute or chronic topical retinoic acid treatment of human skin in vivo alters the expression of epidermal transglutaminase, loricrin, involucrin, filaggrin, and keratins 6 and 13 but not keratins 1, 10, and 14.

Histologic and immunocytochemical analyses were performed on cutaneous biopsies from 10 patients treated with retinoic acid under occlusion for 4 d compared to biopsies from 19 patients treated nightly for 16 weeks. Acute application of RA caused epidermal thickening (9 of 10 samples), stratum granulosum thickening (7 of 10), parakeratosis (4 of 10), a marked increase in the number of cell layers expressing epidermal transglutaminase (7 of 10), and focal expression of two non-epidermal keratins, K6 (8 of 10) and K13 (2 of 10), changes also observed with chronic treatment. Involucrin, filaggrin, and loricrin were also altered in samples from both acute and chronic treatment. An increased number of cell layers expressed both involucrin and filaggrin from both the acute (7 of 10) and chronic (14 of 19) treatment groups. In the acute group, loricrin expression was significantly reduced or absent in some regions of the epidermis (5 of 10), whereas most chronic samples showed an increased number of cell layers expressing loricrin (12 of 19). The pattern of expression of three major epidermal differentiation products, keratins K1, K10, and K14, was not significantly altered in any of the acute or chronic samples, although there was a slight reduction in the detection of K10 in two of the acute samples. Thus, acute topical RA treatment under occlusion caused substantial changes in the epidermis, and reproduced most, but not all of the effects of chronic treatment.