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Raymond Lai

Publications and source records attributed to Raymond Lai.

At least 37 records · Page 2Linked to original sources
PubMed2005

Curcumin (diferuloylmethane) inhibits constitutive NF-kappaB activation, induces G1/S arrest, suppresses proliferation, and induces apoptosis in mantle cell lymphoma.

Human mantle cell lymphoma (MCL), an aggressive B cell non-Hodgkin's lymphoma, is characterized by the overexpression of cyclin D1 which plays an essential role in the survival and proliferation of MCL. Because of MCL's resistance to current chemotherapy, novel approaches are needed. Since MCL cells are known to overexpress NF-kappaB regulated gene products (including cyclin D1), we used curcumin, a pharmacologically safe agent, to target NF-kappaB in a variety of MCL cell lines. All four MCL cell lines examined had overexpression of cyclin D1, constitutive active NF-kappaB and IkappaB kinase and phosphorylated forms of IkappaBalpha and p65. This correlated with expression of TNF, IkappaBalpha, Bcl-2, Bcl-xl, COX-2 and IL-6, all regulated by NF-kappaB. On treatment of cells with curcumin, however, downregulated constitutive active NF-kappaB and inhibited the consitutively active IkappaBalpha kinase (IKK), and phosphorylation of IkappaBalpha and p65. Curcumin also inhibited constitutive activation of Akt, needed for IKK activation. Consequently, the expression of all NF-kappaB-regulated gene products, were downregulated by the polyphenol leading to the suppression of proliferation, cell cycle arrest at the G1/S phase of the cell cycle and induction of apoptosis as indicated by caspase activation, PARP cleavage, and annexin V staining. That NF-kappaB activation is directly linked to the proliferation of cells, is also indicated by the observation that peptide derived from the IKK/NEMO-binding domain and p65 suppressed the constitutive active NF-kappaB complex and inhibited the proliferation of MCL cells. Constitutive NF-kappaB activation was found to be due to TNF, as anti-TNF antibodies inhibited both NF-kappaB activation and proliferation of cells. Overall, our results indicate that curcumin inhibits the constitutive NF-kappaB and IKK leading to suppression of expression of NF-kappaB-regulated gene products that results in the suppression of proliferation, cell cycle arrest, and induction of apoptosis in MCL.

Active Transport, Cell Nucleus↗
PubMed2005

Jak3 activation is significantly associated with ALK expression in anaplastic large cell lymphoma.

Janus kinase 3 (Jak3) is a tyrosine kinase that activates signal transducer and activator of transcription 3 (Stat3) in response to cytokine stimulation. Stat3 is an oncogene. In previous studies of anaplastic large cell lymphoma (ALCL), we showed that inhibition of Jak3 down-regulates activated/phosphorylated Stat3 (pStat3), decreases anaplastic lymphoma kinase (ALK) enzymatic activity, and induces cell-cycle arrest and apoptosis in ALK-positive ALCL. These findings implicate Jak3 as playing a significant role in the pathogenesis of ALK-positive ALCL; most likely via Stat3 and ALK activation. To assess this possibility, we used immunohistochemical staining to evaluate the frequency of expression of Jak3 and its activated/phosphorylated form (pJak3) in 48 systemic ALCL tumors included in a tissue microarray. pJak3 was detected in 17 (81%) of 21 ALK-positive tumors, compared with 3 (11%) of 27 ALK-negative tumors (P < .0001, Fisher exact test). pStat3 was present in 12 (86%) of 14 ALK-positive tumors and in 10 (40%) of 25 ALK-negative tumors assessed (P = .0078). Of 12 ALK-positive/pStat3-positive tumors, 8 (67%) expressed pJak3, but none of 10 ALK-negative/pStat3-positive tumors expressed pJak3. We conclude that Jak3 activation is predominantly restricted to ALK-positive ALCL tumors. Most likely, Jak3 collaborates with ALK in activating Stat3, leading to cell survival, cell-cycle progression, and tumor growth. In contrast, the mechanism of Stat3 activation in ALK-negative ALCL tumors appears to be independent of Jak3.

Adolescent↗
PubMed2005

Constitutive activation of JAK3/STAT3 in colon carcinoma tumors and cell lines: inhibition of JAK3/STAT3 signaling induces apoptosis and cell cycle arrest of colon carcinoma cells.

Signal transducer and activator of transcription 3 (STAT3) has oncogenic potential. The biological effects of STAT3 have not been studied extensively in the pathogenesis of colon cancer, nor has the role of Janus kinase 3 (JAK3), the physiological activator of STAT3, been evaluated. Here, we demonstrate that activated STAT3 (pSTAT3) and activated JAK3 (pJAK3) are expressed constitutively in two colon cancer cell lines, SW480 and HT29. To evaluate the significance of JAK3/STAT3 signaling, we inhibited JAK3 with AG490 and STAT3 with a dominant-negative construct. Inhibition of JAK3 down-regulated pSTAT3. The blockade of JAK3/STAT3 signaling significantly decreased viability of colon cancer cells due to apoptosis and cell-cycle arrest through down-regulation of Bcl-2, Bcl-X(L), Mcl-1, and cyclin D2 and up-regulation of p21(waf1/cip1) and p27(kip1). We also examined histological sections from 22 tumors from patients with stage II or stage IV colon cancer and found STAT3, JAK3, and their activated forms to be frequently expressed. Furthermore, quantitative reverse transcriptase-polymerase chain reaction identified JAK3 mRNA in colon cancer cell lines and primary tumors. Our findings illustrate the biological importance of JAK3/STAT3 activation in the oncogenesis of colon cancer and provide novel evidence that JAK3 is expressed and contributes to STAT3 activation in this malignant neoplasm.

Aged↗
PubMed2005

Analysis of human equilibrative nucleoside transporter 1 (hENT1) protein in non-Hodgkin's lymphoma by immunohistochemistry.

The human equilibrative nucleoside transporter 1 (hENT1) is a member of the equilibrative nucleoside transporter family that mediates cellular entry of gemcitabine, cytarabine, and fludarabine. Deficiency in hENT1 confers resistance to toxicity of these drugs in a variety of model systems. Since some nucleoside analogs have a role in treating patients with non-Hodgkin's lymphoma (NHL), this study was undertaken to assess hENT1 abundance in NHL. A total of 115 cases of NHL of various subtypes and 15 reactive lymph nodes were evaluated for the presence of hENT1 protein using immunohistochemistry applied to frozen tissues. Samples were considered positive when >or=50% of neoplastic cells showed immunostaining. In reactive lymph nodes, hENT1 was confined to the germinal centers, whereas mantle zone B-cells and interfollicular T-cells were negative. In NHL, a relatively high frequency of hENT1 positivity was found in Burkitt lymphoma/leukemia (63%), diffuse large B-cell lymphoma (DLCL; 45%), and follicular lymphoma (40%). In DLCL, 26% of cases were positive for CD10, and CD10-positive DLCL cases were more likely to be hENT1 positive than CD10-negative cases (P=0.025). A lower frequency of hENT1 positivity was found in mantle cell lymphoma (13%) and peripheral T-cell lymphomas (37%). All marginal zone lymphomas (n=5), chronic lymphocytic leukemia small lymphocytic lymphomas (n=10), plasmacytoma (n=3), acute lymphoblastic lymphoma/leukemia, and anaplastic large-cell lymphomas (n=5) were negative. In conclusion, hENT1 was most frequently found in benign and malignant follicular center cells. Prospective studies to assess the value of hENT1 immunostaining in predicting resistance to nucleoside chemotherapy for NHL are warranted.

Equilibrative Nucleoside Transporter 1↗
PubMed2005

Immunohistochemical detection of cdc2 is useful in predicting survival in patients with mantle cell lymphoma.

Recent cDNA microarray studies have reported the prognostic value of several genes in mantle cell lymphoma patients. We aimed to validate the prognostic significance of three of these genes: alpha-tubulin, cdc2, and CENP-F. The protein expression of alpha-tubulin, cdc2, and CENP-F was assessed using immunohistochemistry. Their immunoreactivity in 48 formalin-fixed/paraffin-embedded mantle cell lymphoma tumors was determined by estimating the percentage of positive cells. These results were correlated with the expression of proliferation marker Ki67 and survival. Of these 48 mantle cell lymphoma patients, 41 were men and seven were women. The median age at time of diagnosis was 64.5 years, and the overall median survival was 40 months. In benign lymph nodes, the expression of cdc2 and alpha-tubulin was restricted to the germinal centers; mantle zones were negative. Expression of CENP-F was more uniformly distributed. In mantle cell lymphoma, Ki67 significantly correlated with all three markers (P<0.05, Spearman), but only Ki67 (>50%) and cdc2 (>25%) significantly correlated with shorter survival (P<0.0006, Spearman). Of several clinical parameters examined, international prognostic index of >or=2 correlated with worse clinical outcome, and high clinical stage (ie 4 vs <or=3) showed a trend for shorter survival. The prognostic significance of cdc2 and Ki67 was independent of international prognostic index and clinical stage. We have validated the prognostic value of cdc2, and confirmed that of Ki67, in a cohort of mantle cell lymphoma patients. Immunohistochemical detection of cdc2 and Ki67 may be a useful and simple method in evaluating the prognosis of mantle cell lymphoma patients.

Aged↗
PubMed2005

Severe chronic active Epstein-Barr virus infection mimicking steroid-dependent inflammatory bowel disease.

Severe chronic active Epstein-Barr virus infection is a rare, debilitating, nonneoplastic, inflammatory disorder for which there is no definitive treatment. We describe a Caucasian child who initially presented with clinical and histopathologic features consistent with inflammatory bowel disease, for whom additional investigations led to the diagnosis of severe chronic active Epstein-Barr virus infection.

Biopsy, Needle↗
PubMed2005

Differential expression of WT1 gene product in non-Hodgkin lymphomas.

The tumor suppressor gene wt1 (Wilms tumor 1) encodes a zinc finger transcription factor reported to be expressed in many tumors, including mesotheliomas, carcinomas, and acute leukemias. However, WT1 expression in non-Hodgkin lymphomas (NHLs) has not been studied. The authors assessed for WT1 expression in six lymphoma/leukemia cell lines using Western blot methods after subcellular fractionation. We also assessed for WT1 expression in 167 NHLs using immunohistochemical methods. The B-cell NHLs analyzed were 18 diffuse large B-cell lymphomas, 13 marginal zone B-cell lymphomas, 9 small lymphocytic lymphomas, (DLBCLs), 8 follicular lymphomas, 6 mantle cell lymphomas, 5 Burkitt lymphomas, 3 lymphoplasmacytic lymphomas, and 2 B-cell lymphoblastic lymphomas. The T-cell NHLs analyzed were 43 anaplastic large cell lymphomas (ALCLs), 26 peripheral T-cell lymphomas unspecified, 13 angioimmunoblastic T-cell lymphomas, 6 cutaneous ALCLs, 6 cases of mycosis fungoides, 5 extranodal NK/T-cell lymphomas of nasal type, and 4 T-cell lymphoblastic lymphomas. WT1 levels were higher in cytoplasmic extracts than in nuclear extracts of the Karpas 299 and SU-DHL-1 lymphoma cell lines but were higher in nuclear extracts than in the cytoplasmic extracts of the Jurkat, HH, U-937, and K562 leukemia cell lines. In NHLs, WT1 was positive in 4 of 5 (80%) Burkitt lymphomas, 9 of 12 (75%) ALK-positive ALCLs, 3 of 6 (50%) lymphoblastic lymphomas (2 of 4 T-cell, 1 of 2 B-cell), 14 of 31 (45%) ALK-negative ALCLs, 6 of 18 (33%) DLBCLs, and 1 of 6 (17%) cutaneous ALCLs. WT1 was negative in all other NHLs tested. WT1 immunoreactivity was primarily cytoplasmic in all positive NHLs except T-cell lymphoblastic lymphoma. In conclusion, WT1 protein is frequently detected in the cytoplasm of a subset of high-grade NHLs.

B-Lymphocytes↗
PubMed2005

Class III beta-tubulin expression in tumor cells predicts response and outcome in patients with non-small cell lung cancer receiving paclitaxel.

Both fundamental and clinical studies suggest that class III beta-tubulin expression is associated with resistance to taxanes and constitutes a prognostic factor in several solid tumors. In this study, we assessed the prognostic and predictive value of class III beta-tubulin in tumors of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) treated with paclitaxel-based or other regimens that did not include tubulin-binding agents. Expression of class III beta-tubulin was examined immunohistochemically in 91 tumor samples obtained before treatment from patients with stage III and IV NSCLC, including 47 who received paclitaxel-based regimens and 44 who received regimens without tubulin-binding agents. Response to chemotherapy, progression-free survival, and overall survival were correlated with the expression of class III beta-tubulin protein. The response rate was 37.5% (16 responses among 45 evaluable patients) among patients receiving paclitaxel. Patients whose tumors expressed low levels of class III beta-tubulin isotype had a better response rate, longer progression-free survival, and overall survival (P < 0.001, 0.004, and 0.002, respectively), whereas this variable was not found to be predictive in patients receiving regimens without tubulin-binding agents. A multivariate analysis taking into account sex, age, histology, stage, and class III beta-tubulin confirmed that low-level class III beta-tubulin expression was independently correlated with progression-free survival (P = 0.003) and overall survival (P = 0.003). These findings suggest that the expression levels of class III beta-tubulin in tumor cells is predictive of response to therapy and patient outcome in patients with NSCLC receiving paclitaxel-based chemotherapy but is not a general prognostic factor in this patient population.

Adult↗
PubMed2005

Activation status of the JAK/STAT3 pathway in mantle cell lymphoma.

CONTEXT: Signal transducer and activator of transcription 3 (STAT3) is oncogenic, and we previously found evidence of constitutive STAT3 activation in a relatively small number of frozen mantle cell lymphoma (MCL) cell tumors. OBJECTIVES: To comprehensively survey the activation and phosphorylation status of STAT3 in MCL and to assess if STAT3 activation in these tumors is due to cytokine stimulation by examining the phosphorylation and activation status of Janus kinase (JAK), the physiologic activator of STAT3. DESIGN: We evaluated 43 formalin-fixed, paraffin-embedded MCL tumors using immunohistochemistry and phospho-specific antibodies against STAT3 and JAK. RESULTS: There were 37 small cell and 6 blastoid cases. There was heterogeneous expression of phospho-STAT3 (pSTAT3), with 23 negative cases (53%), 12 weakly positive cases (28%), and 8 strongly positive cases (19%). JAK3 was the only member detectable in 3 MCL cell lines, and immunoprecipitation data showed a relatively low level of tyrosine phosphorylation of JAK3 in these cells. Using immunohistochemistry, phospho-JAK3 (pJAK3) was detectable in 18 (44%) of 41 MCL tumors examined, and pJAK3 expression correlated with that of pSTAT3 (P = .008). A notable exception to this correlation was seen in the blastoid variant, since 4 (67%) of 6 blastoid cases were pSTAT3 positive but pJAK3 negative. CONCLUSIONS: We have confirmed our previous finding that STAT3 is constitutively activated in MCL tumors, with an overall frequency of 47% in this series. STAT3 activation in the small cell but not the blastoid variant of MCL is likely mediated by JAK3.

Adult↗
PubMed2004

The absence of human equilibrative nucleoside transporter 1 is associated with reduced survival in patients with gemcitabine-treated pancreas adenocarcinoma.

PURPOSE: Gemcitabine monotherapy is the standard palliative chemotherapy for pancreatic adenocarcinoma. Gemcitabine requires plasma membrane nucleoside transporter proteins to efficiently enter cells and exert it cytotoxicity. In vitro studies have demonstrated that deficiency of human equilibrative nucleoside transporter 1 (hENT1), the most widely abundant and distributed nucleoside transporter in human cells, confers resistance to gemcitabine toxicity, but the distribution and abundance of nucleoside transporters in normal and malignant pancreatic tissue is unknown. EXPERIMENTAL DESIGN: We studied tumor blocks from normal pancreas and 21 Alberta patients with gemcitabine-treated pancreatic cancer. Immunohistochemistry on the formalin-fixed, paraffin-embedded tissues was performed with specific hENT1 and human Concentrative Nucleoside Transporter 3 monoclonal antibodies and scored by a pathologist blinded to clinical outcomes. RESULTS: hENT1 was detected in normal Langerhan cells and lymphocytes but not in normal glandular elements. Patients in whom all adenocarcinoma cells had detectable hENT1 had significantly longer median survivals from gemcitabine initiation than those for whom hENT1 was absent in a proportion (10 to 100%) of adenocarcinoma cells (median survival, 13 versus 4 months, P = 0.01). Immunohistochemistry for human Concentrative Nucleoside Transporter 3 revealed moderate to high-intensity staining in all adenocarcinoma tissue samples. CONCLUSIONS: Patients with pancreatic adenocarcinoma with uniformly detectable hENT1 immunostaining have a significantly longer survival after gemcitabine chemotherapy than tumors without detectable hENT1. Immunohistochemistry for hENT1 shows promise as a molecular predictive assay to appropriately select patients for palliative gemcitabine chemotherapy but requires formal validation in prospective, randomized trials.

Adenocarcinoma↗
PubMed2004

Quantitative analysis of nucleoside transporter and metabolism gene expression in chronic lymphocytic leukemia (CLL): identification of fludarabine-sensitive and -insensitive populations.

Resistance to fludarabine is observed in the clinic, and molecular predictive assays for benefit from chemotherapy are required. Our objective was to determine if expression of nucleoside transport and metabolism genes was associated with response to fludarabine therapy in patients with chronic lymphocytic leukemia (CLL). CLL cells from 56 patients were collected prior to treatment with fludarabine. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on sample RNA to determine the relative levels of mRNA of 3 nucleoside transporters that mediate fludarabine uptake (human equilibrative nucleoside transporter 1 [hENT1], human equilibrative nucleoside transporter 2 [hENT2], and human concentrative nucleoside transporter 3 [hCNT3]), deoxycytidine kinase (dCK), and 3 5'-nucleotidases (ecto-5'nucleotidase [CD73], deoxynucleotidase-1 [dNT-1], and cytoplasmic high-Km 5-nucleotidase [CN-II]). Two-dimensional hierarchical cluster analysis of gene expression identified 2 distinct populations of CLL. Cluster 2 patients experienced a 3.4-fold higher risk of disease progression than cluster 1 patients (P = .0058, log-rank analysis). Furthermore, independent analysis of the individual genes of interest revealed statistically significant differences for risk of disease progression (adjusted hazard ratios [HRs]) with underexpression of dNT-1 (HR = 0.45; P = .042), CD73 (HR = 0.40; P = .022), and dCK (HR = 0.0.48; P = .035), and overexpression of hCNT3 (HR = 4.7; P = .0007) genes. Subjects with elevated hCNT3 expression experienced a lower complete response rate to fludarabine therapy (11% vs 69%; P = .002). No hCNT3-mediated plasma membrane nucleoside transport was detected in CLL samples expressing hCNT3 message, and hCNT3 protein was localized to the cytoplasm with immunohistochemical and confocal microscopy.

Adult↗
PubMed2004

Inhibition of Akt increases p27Kip1 levels and induces cell cycle arrest in anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL) is a highly proliferative neoplasm that frequently carries the t(2;5)(p23;q35) and aberrantly expresses nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). Previously, NPM-ALK had been shown to activate the phosphatidylinositol 3 kinase (PI3K)/Akt pathway. As the cyclin-dependent kinase (CDK) inhibitor p27(Kip1) (p27) is usually not expressed in ALCL, we hypothesized that activated Akt (pAkt) phosphorylates p27 resulting in increased p27 proteolysis and cell cycle progression. Here we demonstrate that inhibition of pAkt activity in ALCL decreases p27 phosphorylation and degradation, resulting in increased p27 levels and cell cycle arrest. Using immunohistochemistry, pAkt was detected in 24 (57%) of 42 ALCL tumors, including 8 (44%) of 18 ALK-positive tumors and 16 (67%) of 24 ALK-negative tumors, and was inversely correlated with p27 levels. The mean percentage of p27-positive tumor cells was 5% in the pAkt-positive group compared with 26% in the pAkt-negative group (P = .0076). These findings implicate that Akt activation promotes cell cycle progression through inactivation of p27 in ALCL.

Cell Cycle Proteins↗
PubMed2004

Selective inhibition of STAT3 induces apoptosis and G(1) cell cycle arrest in ALK-positive anaplastic large cell lymphoma.

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is an aberrant fusion gene product expressed in a subset of cases of anaplastic large cell lymphoma (ALCL). It has been shown that NPM-ALK binds to and activates signal transducer and activator of transcription 3 (STAT3) in vitro, and that STAT3 is constitutively active in ALK(+) ALCL cell lines and tumors. In view of the oncogenic potential of STAT3, we further examined its biological significance in ALCL using two ALK(+) ALCL cell lines (Karpas 299 and SU-DHL-1) and an adenoviral vector that carries dominant-negative STAT3 (AdSTAT3DN). Infection by AdSTAT3DN led to the expression of STAT3DN in both ALK(+) ALCL cell lines at a similar efficiency. Subcellular fractionation studies showed that a significant proportion of the expressed STAT3DN protein translocated to the nucleus, despite the fact that STAT3DN has a mutation at residue 705(tyrosine --> phenylalanine), a site that is believed to be crucial for STAT3 activation and nuclear translocation. Introduction of STAT3DN induced apoptosis and G(1) cell cycle arrest. Western blot studies showed that expression of STAT3DN resulted in caspase-3 cleavage, downregulation of Bcl-2, Bcl-xL, cyclin D3, survivin, Mcl-1, c-Myc and suppressor of cytokine signaling 3. These results support the concept that STAT3 activation is pathogenetically important in ALCL cells by deregulating the expression of multiple target proteins that are involved in the control of apoptosis and cell cycle progression.

Apoptosis↗
PubMed2004

Survivin expression predicts poorer prognosis in anaplastic large-cell lymphoma.

PURPOSE: Survivin, a member of the inhibitor of apoptosis (IAP) family, is not detected in normal adult tissues but is overexpressed in various cancers, including some types of lymphoma. The frequency and prognostic significance of survivin expression in anaplastic large-cell lymphoma (ALCL) is unknown. MATERIALS AND METHODS: We assessed for survivin expression in 62 ALCL tumors (30 anaplastic lymphoma kinase [ALK]-positive and 32 ALK-negative) obtained before doxorubicin-based chemotherapy. Given that survivin is a target of the STAT3 signaling pathway and STAT3 is activated in ALCL, survivin expression was also correlated with STAT3 activation. RESULTS: Survivin was expressed in 34 tumors (55%) and did not correlate with ALK. A significant association between survivin expression and STAT3 activation was observed (P =.007, Fisher's exact test). For the ALK-positive group, the 5-year failure-free survival (FFS) was 34% for patients with survivin-positive ALCL compared with 100% for patients with survivin-negative ALCL (P =.009, log-rank test). For the ALK-negative group, the 5-year FFS was 46% for patients with survivin-positive tumors compared with 89% for patients with survivin-negative tumors (P =.03, log-rank test). Overall survival was similarly worse for patients with survivin-positive tumors in both the ALK-positive and ALK-negative groups. Furthermore, multivariate analysis confirmed the independent prognostic value of survivin expression, along with age older than 60 years and Ann Arbor stage III or IV. CONCLUSION: Survivin is expressed in approximately half of ALCL tumors and independently predicts unfavorable clinical outcome. Modulation of survivin expression or function may provide a novel target for experimental therapy in patients with ALCL.

Acute-Phase Proteins↗
PubMed2004

Signal transducer and activator of transcription-3 activation contributes to high tissue inhibitor of metalloproteinase-1 expression in anaplastic lymphoma kinase-positive anaplastic large cell lymphoma.

The tissue inhibitor of metalloproteinase-1 (TIMP1) is expressed in a subset of malignant lymphomas and can inhibit tumor spread and promote cell survival. Recent data suggest that TIMP1 expression may be regulated by signal transducer and activator of transcription (STAT)-3. Thus, we tested the hypothesis that TIMP1 expression is related to STAT3 activation in lymphomas, with a focus on anaplastic large cell lymphomas (ALCLs), which are known to express high levels of phosphorylated/active STAT3 (pSTAT3). Specific inhibition of STAT3 with a dominant-negative construct led to concentration-dependent down-regulation of TIMP1 expression in two anaplastic lymphoma kinase (ALK)(+) ALCL cell lines, Karpas 299 and SU-DHL-1. Using cDNA microarrays, ALK(+) ALCL cell lines consistently expressed the highest TIMP1 level among 29 lymphoma cell lines of various subtypes. The association between TIMP1 expression and high level of STAT3 activation was validated by Western blots and immunostaining using antibodies specific for pSTAT3 and TIMP1. We further evaluated the relationship between TIMP1 expression and STAT3 activation in 43 ALCL tumors (19 ALK(+) and 24 ALK(-)) using immunohistochemistry and a tissue microarray. The TIMP1(+) group had a mean of 64% pSTAT3(+) cells as compared to 23% pSTAT3(+) cells in the TIMP1(-) group (P = 0.002). As expected, TIMP1 positivity was higher in the ALK(+) group (15 of 19, 79%) compared with the ALK(-) group (5 of 24, 21%; P = 0.0002) because NPM-ALK restricted to ALK(+) tumors was previously shown to activate STAT3. In conclusion, STAT3 directly contributes to the high level of TIMP1 expression in ALK(+) ALCL, and TIMP1 expression correlates with high level of STAT3 activation in ALCL. TIMP1, as a downstream target of STAT3, may mediate the anti-apoptotic effects of STAT3.

Anaplastic Lymphoma Kinase↗
PubMed2004

Retinoblastoma protein is frequently absent or phosphorylated in anaplastic large-cell lymphoma.

The possible role of retinoblastoma protein (Rb) in the pathogenesis of anaplastic large-cell lymphoma (ALCL) is unknown. We investigated Rb protein expression, both total (phosphorylated and underphosphorylated) and active (underphosphorylated), in four anaplastic lymphoma kinase (ALK)-positive ALCL cell lines (Karpas 299, JB-6, SU-DHL1, and SR-786) by Western blot analysis, and in 67 ALCL tumors (30 ALK-positive, 37 ALK-negative) using immunohistochemical methods. We also used fluorescence in situ hybridization and polymerase chain reaction methods to assess for loss of heterozygosity of the rb gene. The findings were correlated with apoptotic rate assessed by the terminal dUTP nick-end labeling assay. Immunoblots showed high total Rb levels in Karpas 299, SU-DHL1 and SR-786 and relatively lower levels in and JB-6. Underphosphorylated Rb was negative or expressed at low levels in all cell lines. In ALCL tumors, total Rb was detected in 44 (66%) and absent in 23 (34%). The mean apoptotic rate was 3.2% in Rb-negative tumors compared with 2.7%, 2.2%, and 1.2% in tumors with <10%, 10 to 50%, and >50% Rb-positive cells, respectively (P = 0.2, Kruskall-Wallis test). In a subset of 25 total Rb-positive tumors we assessed for underphosphorylated Rb, which was detected in 12 tumors. The detection of only total Rb in the remaining 13 tumors suggests that Rb was phosphorylated. Fluorescence in situ hybridization showed allelic loss of the rb gene in 10 (40%) of 25 tumors analyzed and was significantly associated with absence of Rb expression (P = 0.003). Similar results were obtained for loss of heterozygosity of the 13q14 locus. Five-year progression-free survival for patients with Rb-negative ALCL was 89.4% compared with 47.7% for patients with total Rb-positive ALCL (P = 0.006, log-rank test). Similar trends for progression-free survival held true for patients with ALK-positive and ALK-negative tumors analyzed separately. In conclusion, Rb is absent or phosphorylated in most ALCL cell lines and tumors and absence of Rb expression is associated with better clinical outcome in patients with ALCL.

Aged↗