Association Of Bcl-2 Expression Research Articles

Abstract C098: Racial disparity in the prevalence of BCL-2 expression and associations with breast cancer survival in the Breast Cancer Care in Chicago study

Abstract Background: BCL-2 is an antiapoptotic protein that regulates apoptosis and has been associated with poor prognosis for many cancer sites. Despite a function that encourages tumorigenesis, increased BCL-2 expression has been associated with improved clinical outcomes in ER+ breast cancers, with mixed results observed for ER/PR- cancers. BCL-2 has been hypothesized to be an indicator of intact and fully functioning hormone receptor pathways and has also been hypothesized to facilitate cell death after treatment through mitochondrial priming. BCL-2 expression correlates strongly with hormone receptor expression; therefore, its association with better prognosis may be due to the strong effect ER/PR status has on survival, or due to its own biologic mechanism. To date, no studies have been conducted on racial differences in BCL-2 expression. We characterized racial/ethnic differences in BCL-2 expression and the association of BCL-2 expression with breast cancer specific survival among participants in the Breast Cancer Care in Chicago Study (BCCC). Methods: The BCCC was a cross-sectional study of 989 recently diagnosed non-Latina (nL) White, nL Black and Latina breast cancer patients diagnosed with a first primary breast cancer aged 30-79 in Chicago from 2005-2008. Tumor tissue was available for BCL-2 immunohistochemical staining for 264 patients. BCL-2 staining scores of 0 were classified as negative and all positive scores (1D, 1H, 2D, 2H, and 3) were classified as positive. Cox proportional hazards models were conducted to estimate the association of BCL-2 expression with breast cancer-specific death. Results: Roughly three-fourths of tumors (77%) stained positive for BCL. The prevalence of positive BCL staining varied by race/ethnicity (p=0.007), being highest for nL Whites (87%) and lowest for nL Blacks (68%); variability in BCL staining appeared to be limited to ER/PR-negative tumors (N=53), for which prevalence of positive BCL staining appeared to be much higher for nL whites than for minority patients (44% vs. 16%, p=0.054). BCL-2 expression was associated with a strong protective effect on BC survival in age and race-adjusted models (HR=0.40, 95% CI: 0.19, 0.84) and BCL-2 expression remained strongly positively associated with protection from breast cancer death with additional adjustment for ER/PR status (HR=0.33, 95% CI: 0.12, 0.89). Within subgroups defined by ER/PR status, BCL2 expression was qualitatively associated with better survival for both ER/PR positive and ER/PR negative subtypes, although sample size was insufficient to conduct a formal stratified analysis. Conclusions: BCL-2 appears to be an independent predictor of improved prognosis for breast cancer even after controlling for ER/PR status. The apparently higher prevalence of BCL2 expression for nL White vs. nL Black patients may provide etiologic clues regarding disparities in BC survival. Citation Format: Jibril M. Alim, Kent Hoskins, Abeer M. Mahmoud, Virgilia Macias, Andre Kadjascy-Balla, Garth H. Rauscher. Racial disparity in the prevalence of BCL-2 expression and associations with breast cancer survival in the Breast Cancer Care in Chicago study [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C098.

Histopathological Evaluation and Analysis of Immunohistochemical Expression of Bcl-2 Oncoprotein in Colorectal Carcinoma.

Background & Objective:Colorectal cancer is the third most prevalent malignancy with high mortality rate, necessitating markers that predict survival and guide the treatment. Previous studies have examined the immunohistochemical expression of Bcl-2, an apoptotic marker, in colorectal carcinoma, but results have been contradictory. To evaluate the histopathological features of colorectal carcinoma, immunohistochemical expression of Bcl-2 must be analyzed to find out statistical association of Bcl-2 expression with certain prognostic factors histopathologic type, grade and TNM staging. Methods:This prospective study was conducted on the colectomy specimens of colorectal carcinoma, over a period of two years. The tumor morphology and Bcl-2 status were evaluated by immunohistochemistry in each case.Results:The study included 58 cases, with mean patient age of 47.07 years and male: female ratio of 1.89:1. Bcl-2 positivity was seen in 32.7% of the cases. Weak, moderate, and strong expression of Bcl-2 was seen in 12.1%, 12.1%, and 8.5% of cases respectively. Even though early stages of colorectal carcinoma showed greater frequency of Bcl-2 expression than advanced stages (36.3% versus 28%), however this association was not statistically significant. Conclusion:Lack of statistically significant correlation between Bcl-2 immuno-histochemical expression and prognostic parameters like tumor grade and stage, suggests that Bcl-2 immunoexpression may not be a significant prognostic marker in colorectal carcinoma.

The Influential Role of BCL2 Family Members in Synovial Sarcomagenesis.

Synovial sarcomas are deadly soft tissue malignancies associated with t(X;18) balanced chromosomal translocations. Expression of the apoptotic regulator BCL2 is prominent in synovial sarcomas and has prompted the hypothesis that synovial sarcomagenesis may depend on it. Herein, it is demonstrated that Bcl2 overexpression enhances synovial sarcomagenesis in an animal model. Furthermore, we determined increased familial clustering of human synovial sarcoma patients with victims of other BCL2-associated malignancies in the Utah Population Database. Conditional genetic disruption of Bcl2 in mice also led to reduced sarcomagenesis. Pharmacologic inhibition specific to BCL2 had no demonstrable efficacy against human synovial sarcoma cell lines or mouse tumors. However, targeting BCLxL in human and mouse synovial sarcoma with the small molecule BH3 domain inhibitor, BXI-72, achieved significant cytoreduction and increased apoptotic signaling. Thus, the contributory role of BCL2 in synovial sarcomagenesis does not appear to render it as a therapeutic target, but mitochondrial antiapoptotic BCL2 family members may be.Implications: The association of BCL2 expression with synovial sarcoma is found to fit with a subtle, but significant, impact of its enhanced presence or absence during early tumorigenesis. However, specific pharmacologic inhibition of BCL2 does not demonstrate a persistent dependence in fully developed tumors. Conversely, inhibition of the BCL2 family member BCLxL resulted in nanomolar potency against human synovial sarcoma cell lines and 50% tumor reduction in a genetically engineered mouse model. Mol Cancer Res; 15(12); 1733-40. ©2017 AACR.

Expression of Bcl-2 gene and its effect on prognosis of patients with primary gastrointestinal diffuse large B-cell lymphoma

To explore the expression of Bcl-2 mRNA and its effect on prognosis of patients with primary gastrointestinal diffuse large B-cell lymphoma (PGI-DLBCL). Real time quantitative PCR was used to determine the expression of Bcl-2 mRNA in 40 PGI-DLBCL patients and 17 healthy controls. The association of Bcl-2 expression with clinicopathological features and prognosis of the patients was analyzed. The expression level of Bcl-2 mRNA in PGI-DLBCL patients was 1.03 ± 0.93, significantly higher than that of the controls (0.41 ± 0.21) (P < 0.05). The expression of Bcl-2 mRNA in stage IIE-IV patients (1.28 ± 1.01) was significantly higher than that in the stage I-II2 patients (0.62 ± 0.61) (P < 0.05). The expression of Bcl-2 mRNA in patients with international prognostic index (IPI) score >2 (1.95 ± 1.27) was significantly higher than those with IPI score ≤ 2 (0.86 ± 0.75)(P < 0.05). The expression of Bcl-2 mRNA in patients with complete remission (CR) (0.71 ± 0.58) was significantly lower vs. 2.42 ± 0.91 in patients with no CR (P < 0.05). Univariate analysis indicated that β2-MG, IPI score>2, the Lugano staging, and Bcl-2 mRNA expression were associated with overall survival (OS) and progression-free survival (PFS) (P < 0.05). Multivariate analysis indicated that IPI score>2 was independently associated with OS (P < 0.05), and both IPI score >2 and Bcl-2 mRNA expression were independently associated with PFS (P < 0.05). The expression of Bcl-2 mRNA in the tumor tissue of PGI-DLBCL patients is significantly higher than that in controls. PGI-DLBCL patients with higher expression of Bcl-2 have a poor chemotherapy response and inferior prognosis. IPI score >2 and higher expression of Bcl-2 mRNA are independent poor prognostic factors for PFS in PGI-DLBCL patients.

BCL2 protein in prediction of relapse in triple-negative breast cancer (TNBC) treated with adjuvant anthracycline-based chemotherapy.

1087 Background: Preclinical data show an association of BCL2 expression and resistance to anthracyclines. The absence of BCL2 expression in prechemotherapy samples is associated with a higher probability of pathological complete response to neoadjuvant doxorubicin-based chemotherapy. The aim of our research is identification of markers predicting sensitivity to adjuvant treatment in TNBC. Here we focus on BCL2 protein as a putative predictor of sensitivity to adjuvant anthracycline-based chemotherapy. The objective was to determine whether BCL2 expression predicts relapse in TNBC patients treated with anthracycline-based regimens. Methods: The study included 187 patients with TNBC, 178 of whom were treated with adjuvant chemotherapy (164 had anthracyclines). BCL2 analysis was performed using IHC, proportion score and intensity score were counted. The data were analysed with software Statistica and R. Results: High BCL2 expression predicts poor relapse free survival (RFS) in patients treated with adjuvant anthracycline-based regimens (logrank p=.035, hazard ratio, HR 2.37, 95%CI 1.04-5.41). High BCL2 predicts trend to poor overall survival (OS) in patients treated with adjuvant anthracycline-based regimens (logrank p=0.075, HR 2.31, 95%CI 0.90-5.97). In univariate analysis of anthracycline treated patients, stage (RFS p=.0004, OS p=.0005), size (RFS p=.003, OS p=.00009) and nodal status (RFS p=0.018, OS p=.028) were associated with outcome, as well. In multivariate analysis of athracycline treated patients, BCL2, size and nodal status had an independent predictive significance for both RFS (p=.005, p=.056, p=.003) (logrank test, p=0.0004) and OS (p=.014, p=.006, p=.012) (logrank test p=0.0007). Conclusions: This study is the first to prove that high BCL2 expression predicts poor outcome in TNBC treated with adjuvant anthracycline-based chemotherapy. BCL2 expression could facilitate decision making on adjuvant treatment in TNBC patients and its assessment should be included in standard diagnostics. In patients with high BCL2 expression other types of adjuvant treatment should be considered. Grants: IGA NS10286,IGA NS10357-3 and Biomedreg CZ.1.05/2.1.00/01.0030.

Does immunointensity account for the differences in prognostic significance of Bcl-2 expression in non-small cell lung cancer?

Bcl-2 is an oncogenic protein that plays a central role in apoptosis. The association of Bcl-2 expression and prognosis in non-small cell lung cancer (NSCLC) is unclear, with some studies showing improved outcome whilst others show no survival advantage. We evaluated 178 surgically resected NSCLC specimens for Bcl-2 and p53 immunoexpression. Bcl-2 staining was present in 34.9% of cases (weakly staining 24.2%, strongly staining 10.7%), nuclear p53 in 43. 3% and cytoplasmic p53 in 10.7%. There was no association between p53 and survival. Bcl-2 immunoexpression correlated with improved outcome (p=0.04). A sub-group of strongly Bcl-2 staining cases had a poor survival compared to those that stained weakly (p=0.01). The strongly staining cases had a similar survival to negative cases. Immunointensity may therefore account for the disparity in results regarding the prognostic significance of Bcl-2 demonstrated in previous studies.

Cell cycle perturbations in acute myeloid leukemia samples following in vitro exposures to therapeutic agents

Cell cycle checkpoints establish the timing and strength of arrest, repair and apoptosis responses to damaging treatments. We designed flow cytometric assays to measure cell cycle arrest and apoptosis in acute myeloid leukemia (AMD samples treated in vitro with relevant therapeutic agents so as to functionally characterize checkpoints in these samples and to ask if checkpoint abnormalities are common in AML and contribute to therapeutic failures. We show here that cell cycle responses to daunomycin (DNR), cytosine arabinoside (ARA-C) and gamma irradiation (RAD) were reproducibly treatment agent- and dose-dependent and distinct in different myeloid cell lines. DNR treatments differentially induced cell accumulations in the gap 2 and mitosis (G2/M) phases of the cell cycle and/or in the gap 1 (G1) phase, as did RAD, while ARA-C induced accumulations in the DMA synthesis (S) phase or in the G1 phase. Flow cytometric gates were devised to exclude lymphocytes and mature neutrophils in analyses of primary myeloid cell samples. Cell subsets in bone marrow samples from normal donors were thus enriched for myeloid constituents and used as normal myeloid cell controls. Proliferating cell nuclear antigen (PCNA) immunostaining was used to further identify actively dividing cell subpopulations in primary cell samples. AML samples were similarly analyzed and the majority showed lower DNA synthesis cell cycle phase (S) fractions and lower PCNA-positive fractions than normal myeloid cells, suggesting that AMLs are generally less proliferative in these culture conditions. Exceptional AML samples with high S phase fractions had cytogenetic abnormalities associated with poor prognosis. Most AML samples mounted weak cell cycle responses relative to normal myeloid cells, while a minority showed robust, agentspecific cell cycle arrests. This non-responsiveness was not simply associated with lower cycling indices—neither the response patterns nor the degrees of response were correlated with untreated S phase fractions or with PCNA-positive fractions. Cell cycle responses were also not associated with clinical parameters including patient age, FAB class, or white blood cell count, nor with immunophenotypic features including CD34 status, nor with specific cytogenetic markers. This suggests that functional cell cycle response assays could provide un:que diagnostic information in AML. These assays might also have prognostic value as ARAC induced G1 arrests and DNR-specific G2/M arrests tended to be associated with failure to achieve clinical remission. In addition, G1 arrests after ARA-C and G2/M accumulations after DNR treatments tended to be more robust in samples that had previously been shown to be more highly immunopositive for bcl-2 expression. This data suggests that the association of bcl-2 expression with particular cell cycle responses to therapeutic agents may contribute to the association of bcl-2 with poor clinical responses in AML. These data provide the basis for further laboratory studies aimed at examining specific cell cycle arrests as mechanisms of therapeutic resistance and prospective studies aimed at rigorously assessing the prognostic utility of in vitro assays of checkpoint function.