Prion protein prevents human breast carcinoma cell line from tumor necrosis factor alpha-induced cell death

To define genetic determinants of tumor cell resistance to the cytotoxic action of tumor necrosis factor alpha (TNF), we have applied cDNA microarrays to a human breast carcinoma TNF-sensitive MCF7 cell line and its established TNF-resistant clone. Of a total of 5760 samples of cDNA examined, 3.6% were found to be differentially expressed in TNF-resistant 1001 cells as compared with TNF-sensitive MCF7 cells. On the basis of available literature data, the striking finding is the association of some differentially expressed genes involved in the phosphatidylinositol-3-kinase/Akt signaling pathway. More notably, we found that the PRNP gene coding for the cellular prion protein (PrP(c)), was 17-fold overexpressed in the 1001 cell line as compared with the MCF7 cell line. This differential expression was confirmed at the cell surface by immunostaining that indicated that PrP(c) is overexpressed at both mRNA and protein levels in the TNF-resistant derivative. Using recombinant adenoviruses expressing the human PrP(c,) our data demonstrate that PrP(c) overexpression converted TNF-sensitive MCF7 cells into TNF-resistant cells, at least in part, by a mechanism involving alteration of cytochrome c release from mitochondria and nuclear condensation.     

Microtubule inhibitor D-24851 induces p53-independent apoptotic cell death in malignant glioma cells through Bcl-2 phosphorylation and Bax translocation

D-24851 is a recently developed microtubule inhibitor that induces G2/M cell-cycle arrest and has an antitumor effect in many cancer cell types. It is expected to be a promising chemotherapeutic agent against a broad range of tumors. However, the precise mechanisms underlying its antitumor effect remain to be determined. Here, we investigated the in vitro effect of D-24851 on tumor growth and the apoptosis mechanism in human malignant glioma cells. Because both p53-dependent and -independent pathways of apoptosis have been reported, we used cell lines with wild-type p53 (U87-MG and D54) and cell lines with mutant p53 (U373-MG and T98G) and compared their responses to D-24851. D-24851 substantially inhibited the proliferation of the four glioma cell lines tested in a dose- and time-dependent manner. The inhibitory effect of D-24851 on tumor growth was associated with cell-cycle arrest in G2/M, subsequently inducing apoptosis. D-24851 treatment induced phosphorylated Bcl-2 and translocated Bax from the cytoplasm to the mitochondria, resulting in apoptotic cell death. These events took place regardless of the p53 status of tumor cells. Our results indicated that D-24851 effectively induces apoptosis through Bcl-2 phosphorylation and Bax translocation in human malignant glioma cells in a p53-independent manner. The results of this study make D-24851 even more promising as a therapeutic agent, especially because many malignant gliomas have a heterogeneous p53 status.     

Taxol-induced ceramide generation and apoptosis in human breast cancer cells

PURPOSE: Taxol has emerged as a valuable antimitotic chemotherapeutic agent, particularly in advanced breast and ovarian cancers. Although much is known about cytotoxic mechanisms, the effectiveness of Taxol cannot be solely explained by microtubular interaction. This study was undertaken to determine whether ceramide generation plays a role in Taxol-induced apoptosis. METHODS: Hormone-independent MDA-MB-468 and hormone-dependent MCF-7 breast cancer cell lines were employed, and ceramide metabolism was characterized using [3H]palmitic acid as lipid precursor. RESULTS: Exposure of cells to Taxol resulted in enhanced formation of [3H]ceramide. Ceramide increased nearly 2-fold in MDA-MB-468 cells exposed to 50 nM Taxol, and more than 2.5-fold in MCF-7 cells exposed to 1.0 microM Taxol. These concentrations mirrored the EC50 (amount of drug eliciting 50% cell kill) for Taxol in the two cell lines. Use of cell-permeable C6-ceramide as a medium supplement revealed that MDA-MB-468 cells were 20-fold more sensitive to ceramide than MCF-7 cells (P < 0.001). Ceramide was generated as early as 6 h after exposure to Taxol in MDA-MB-468 cells, whereas the earliest signs of apoptosis were detected 12 h after treatment, and by 24 h the apoptotic index was six times that of untreated cells. Both fumonisin B1, a ceramide synthase inhibitor, and L-cycloserine, a serine palmitoyltransferase inhibitor, blocked Taxol-induced ceramide generation, whilst sphingomyelin levels remained unchanged, indicating a de novo pathway of ceramide formation. L-Cycloserine reduced Taxol-induced apoptosis by 30% in MDA-MB-468 cells and totally blocked Taxol-induced apoptosis in MCF-7 cells. CONCLUSIONS: These results suggest that Taxol-induced apoptosis is, in part, attributable to ceramide and sphingoid bases. This is of relevance to drug mechanism studies, as ceramide is a known messenger of apoptosis. Clinical use of Taxol with ceramide-enhancing agents may maximize cytotoxic potential.     

Taxol-induced bcl-2 phosphorylation in ovarian cancer cell monolayer and spheroids

Expression of Bcl-2, Bax, p53 and induction of apoptosis were studied in cisplatin or Taxol treated monolayer and spheroid cultures of ovarian cancer cell lines (SKOV-3, UL-1, UL-3C). While cisplatin (15-75 microg/ml) induced apoptosis in monolayer and spheroid cultures, Taxol (100-800 nM) induced fragmentation in monolayers only. Cisplatin induced up to 5-fold DNA fragmentation in monolayers, while 3-fold (UL-3C, SKOV-3), and 1.5-fold (UL-1) in spheroids. Taxol treatment of monolayers resulted in the characteristic phosphorylation of Bcl-2, which was not demonstrated in spheroid cultures. Bax expression was reduced in spheroids following cisplatin or Taxol treatment, while p53 levels remained unchanged.     

Medroxyprogesterone acetate inhibits human pancreatic carcinoma cell growth by inducing apoptosis in association with Bcl-2 phosphorylation

BACKGROUND: A previous study found that medroxyprogesterone acetate (MPA) delayed the in vivo growth of three (AsPC-1, Capan-2, and MiaPaCa-2) of nine human pancreatic carcinoma cell lines transplanted into nude mice (Cancer 1995; 75:1263-72). The current study was undertaken to evaluate the basis for this inhibitor. METHODS: The estrogen receptor (ER) and progesterone receptor (PgR) status in nine human pancreatic carcinoma cell lines, AsPC-1, BxPC-3, Capan-1, Capan-2, Hs-700T, Hs-766T, MiaPaCa-2, PANC-1, and SUIT-2, was assessed using an enzyme immunoassay (EIA). The authors tested the growth inhibitory activity of MPA and the morphologic changes in these nine pancreatic carcinoma cell lines. Cell cycle progression and DNA fragmentation also were evaluated in these cell lines. Immunoblot analysis was used to determine bcl-2 expression and phosphorylation. RESULTS: In the EIA assay, ER was detected in three cell lines (BxPC-3, Capan-2, and MiaPaCa-2), and PgR was also detected in three (AsPC-1, Capan-2, and MiaPaCa-2). Medroxyprogesterone acetate inhibited the growth of three cell lines (AsPC-1, Capan-2, and MiaPaCa-2) with IC50 values ranging from 2.3 x 10(7) to 6.1 x 10(-7) M. In these three responsive cell lines, MPA caused cell detachment and decreased cell density. The nuclei of the MPA-treated cells were condensed and often fragmented. Cell cycle analysis of these three cell lines showed that MPA induced the appearance of a sub-G1 peak, which is characteristic of early apoptotic cells. DNA degradation assay after MPA treatment showed a typical DNA ladder pattern consistent with apoptosis. Immunoblot analysis of MPA-treated cells that overexpressed bcl-2 revealed a pattern consistent with bcl-2 phosphorylation. CONCLUSIONS: Clinically attainable concentrations of MPA can inhibit the growth of some human pancreatic carcinoma cells in vitro by inducing apoptosis, probably through their PgR, in association with the phosphorylation of bcl-2. This agent may be useful for treating patients with pancreatic carcinoma.     

Induction of cell death in antiestrogen resistant human breast cancer cells by the protein kinase CK2 inhibitor DMAT

Protein kinase CK2 is involved in cell proliferation and survival, and found overexpressed in virtually all types of human cancer, including breast cancer. We demonstrate that inhibition of CK2 with 2-dimethylamino-4,5,6,7-tetrabromo-benzimidazole (DMAT), a potent and specific CK2 inhibitor, results in caspase-mediated killing of human breast cancer cells with acquired resistance to antiestrogens, while DMAT fails to kill parental MCF-7 cells. The antiestrogen resistant breast cancer cells express reduced levels of Bcl-2 compared to MCF-7 cells. Reduced Bcl-2 protein level is also found in a tamoxifen resistant human breast tumor grown as a xenograft. We show that re-expression of Bcl-2 partially rescues antiestrogen resistant MCF-7 sublines from DMAT-induced cell death. In summary, our data suggest a novel role of CK2 in antiestrogen resistance.     

Bcl-2表达降低对人乳腺癌细胞米托蒽醌敏感性的影响

目的:探讨抗凋亡蛋白Bcl-2低表达后对人乳腺癌细胞米托蒽醌(mitoxantrone,MX)敏感性的影响。方法:分别用MTT法和流式细胞仪PI单染、Annexin V/PI双染法、彗星实验检测Bcl-2低表达后,MX对乳腺癌MDA-MB-435S和MDA-MB-231细胞生存率、细胞周期、凋亡和DNA损伤的影响。结果:Bcl-2表达降低后MX对乳腺癌MDA-MB-435S和MDA-MB-231细胞的增殖抑制、S期阻滞、凋亡诱导、DNA损伤均明显增加,具有统计学意义。结论:抑制Bcl-2表达可以增加乳腺癌细胞对MX的敏感性。     

Transforming growth factor beta 1 induces apoptotic cell death in cultured human gastric carcinoma cells.

Transforming growth factor beta 1 (TGF-beta 1) is a potent growth inhibitor for many cell types, including tumor cells. We recently have reported the establishment and characterization of two human gastric scirrhous carcinoma cell lines, HSC-39 and HSC-43. Here we examined the effect of TGF-beta 1 on the growth of these lines as compared to five other human gastric adenocarcinoma cell lines. Proliferation of HSC-39 and HSC-43 cells was strongly inhibited by TGF-beta 1, whereas the other gastric adenocarcinoma cell lines were unresponsive to TGF-beta 1. Both HSC-39 and HSC-43 cells gradually lost viability following exposure to TGF-beta 1. This response was dose dependent up to 4 ng/ml. When TGF-beta 1 was removed, the cells failed to exhibit regrowth, indicating an irreversible growth-inhibitory effect of this agent, leading to cell death. DNA fragments were observed consisting of multimers of approximately 180 base pairs 24 h after TGF-beta 1 treatment. The chromatin condensation of each cell line was confirmed by Hoechst 33258 fluorochrome staining. Ultrastructurally, condensed and fragmented nuclei were observed in TGF-beta 1-treated cells. These features are generally associated with apoptotic processes. Both cell death and DNA fragmentation were partially inhibited by cycloheximide, suggesting the requirement for new protein synthesis. Our results suggest that TGF-beta 1 induces cell death in human gastric scirrhous carcinoma cells in vitro which is mediated by activation of a signal transduction pathway for apoptosis.     

Tissue inhibitor of metalloproteinase-1 protects human breast epithelial cells from extrinsic cell death: a potential oncogenic activity of tissue inhibitor of metalloproteinase-1

Tissue inhibitors of metalloproteinases (TIMPs) inhibit matrix metalloproteinases and some members of a disintegrin and metalloproteinase domain (ADAM) family. In addition, recent studies unveiled novel functions of TIMPs in the regulation of apoptosis. TIMP-1 inhibits intrinsic apoptosis by inducing TIMP-1 specific cell survival pathways involving focal adhesion kinase (FAK). TIMP-3, however, was shown to enhance extrinsic cell death by inhibiting the shedding of the cell surface death receptors mediated by tumor necrosis factor-alpha converting enzymes (TACE/ADAM-17). Here, we examined whether TIMP-1, an inhibitor of some of the ADAM family members, enhances the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced extrinsic apoptotic pathway. Surprisingly, we found that TIMP-1 effectively protects human breast epithelial cells from TRAIL-induced apoptosis, demonstrating opposite roles of TIMP-1 and TIMP-3 for the regulation of extrinsic apoptosis. TIMP-1 inhibition of TRAIL-induced apoptosis does not depend on its ability to inhibit matrix metalloproteinases or ADAM activities and is unrelated to its ability to stabilize active or decoy death receptors. Importantly, inhibition of PI 3-kinase signaling by wortmannin and down-regulation of FAK expression using siRNA significantly diminish TIMP-1 protection of human breast epithelial cells against TRAIL-induced extrinsic apoptosis. In addition, the in vitro three-dimensional culture studies showed that TIMP-1 inhibits lumen formation and apoptosis during morphogenesis of MCF10A acini. Taken together, these studies suggest that TIMP-1 may exert oncogenic activity in breast cancer through inhibition of both intrinsic and extrinsic apoptosis involving the FAK survival signal transduction pathway.     

Bcl-2 modulates Fas-mediated apoptosis in human renal cell carcinoma cell lines

The objective of this study was to characterize the role of Bcl-2 expression in Fas-mediated apoptosis in human renal cell carcinoma (RCC) cell lines. RT-PCR analyses showed that 10 different RCC cell lines expressed Fas, but not Fas ligand. Seven of 10 cell lines expressed Fas strongly, while 3 cell lines weakly expressed Fas by flow cytometric analyses. Measurement of the LDH concentration in the culture supernatant revealed that 6 of the 7 cell lines which expressed Fas strongly were sensitive to treatment with an agonistic anti-Fas monoclonal antibody (CH11), whereas all cell lines which weakly expressed Fas did not show Fas-mediated cell death. Furthermore, Bcl-2 expression was found only in three cell lines which were all susceptible to CH11, and the downregulation of Bcl-2 protein by treatment with antisense oligodeoxynucleotide targeting Bcl-2 gene resulted in an enhancement of cell death induced by CH11. These findings suggest that strong Fas expression is necessary for Fas-mediated cell death in RCC cell lines, and Bcl-2 has a protective role against treatment with an anti-Fas monoclonal antibody, despite the fact that Bcl-2 expression was observed only in sensitive cell lines to Fas-mediated cell death.     

Sphingosine kinase activity counteracts ceramide-mediated cell death in human melanoma cells: role of Bcl-2 expression

While most of the pharmacological therapies for melanoma utilize the apoptotic machinery of the cells, the available therapeutic options are limited due to the ability of melanoma cells to resist programmed cell death. Human melanoma cell lines A-375 and M186 are sensitive to ceramide- and Fas-induced cell death, while Mel-2a and M221 are resistant. We have now found that Mel-2a and M221 cells have a significantly higher ceramide/sphingosine-1-phosphate (S1P) ratio than A-375 and M186 cells. As sphingosine kinase (SphK) type 1 plays a critical role in determining the dynamic balance between the proapoptotic sphingolipid metabolite ceramide and the prosurvival S1P, we examined its role in apoptosis of melanoma cells. Increasing SphK1 expression reduced the sensitivity of A-375 melanoma cells to Fas- and ceramide-mediated apoptosis. Conversely, downregulation of SphK1 with small interfering RNA decreased the resistance of Mel-2a cells to apoptosis. Importantly, overexpression of the prosurvival protein Bcl-2 in A-375 cells markedly stimulated SphK1 expression and activity, while downregulation of Bcl-2 reduced SphK1 expression. This link between Bcl-2 and SphK1 might be an additional clue to chemotherapy resistance of malignant melanoma.     

Combination chemotherapy of paclitaxel and cisplatin induces apoptosis with Bcl-2 phosphorylation in a cisplatin-resistant human epidermoid carcinoma cell line

PURPOSE: Paclitaxel (Taxol, TXL) is an antimicrotubule agent that stabilizes microtubules, arrests the cell cycle at the G(2)/M phase and induces apoptosis. In vitro drug sensitivity assays have shown that the combination of TXL and CDDP is more effective in CDDP-resistant ovarian carcinoma cell lines, with different cytotoxicities depending on the sequence of drug exposure. CDDP also shows poor results in human epidermoid carcinoma particularly of the head and neck region. METHODS: We investigated the effects and the molecular mechanisms of combination chemotherapy with TXL and CDDP in the CDDP-resistant cell line A431/CDDP2, and in its parental human epidermoid cell line A431/P. Drug sensitivity was determined using the MTS assay and cell cycle perturbation was analyzed using flow cytometry. DNA fragmentation was then analyzed and the protein levels of caspase-3 and Bcl-2, and phosphorylated of Bcl-2 were determined by Western blotting. RESULTS: In the drug sensitivity assay, exposure to CDDP prior to TXL was more effective than exposure TXL prior to CDDP in A431/P cells. In A431/CDDP2 cells, exposure to TXL prior to CDDP was more effective than exposure to CDDP prior to TXL. Exposure to TXL arrested the cells in the G(2)/M phase in both cell lines. In A431/CDDP2 cells, exposure to TXL prior to CDDP arrested the cells in the G(2)/M phase, an effect caused by either CDDP or TXL. Analysis of DNA fragmentation showed similar results to the drug sensitivity assay. Expression of caspase-3 protein active form was detected following exposure to TXL only and to the TXL/CDDP combination in both A431/P and A431/CDDP2 cells, but phosphorylation of Bcl-2 protein was detected only following exposure to TXL and only in A431/CDDP2 cells. CONCLUSIONS: These results indicate that exposure to TXL prior to CDDP plays a key role in circumventing CDDP resistance by phosphorylating Bcl-2 protein in the human epidermoid carcinoma cell line A431/CDDP2.     

The small organic compound HA14-1 prevents Bcl-2 interaction with Bax to sensitize malignant glioma cells to induction of cell death

A functional imbalance between proapoptotic Bax and antiapoptotic Bcl-2 is likely to participate in the resistance of cancer cells to therapy. We show here that ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (HA14-1), a small organic compound recently proposed to function as an inhibitor of Bcl-2, increases the sensitivity of human glioblastoma cells to radiotherapy and chemotherapy. This sensitizing effect is lost if Bcl-2 expression, but not Bcl-xL expression, is knocked down or if cells only express a mutant of Bax that does not interact with Bcl-2. This points to a specific Bcl-2 inhibitory function of HA14-1 and implies that it selectively involves hindrance of Bcl-2 binding to Bax, which HA14-1 inhibits in cell-free assays and in cells in receipt of an apoptotic stimulation. Moreover, HA14-1, in combination with a cytotoxic treatment, slows down the growth of glioblastoma in vivo. Thus, the inhibition of Bcl-2 achieved by HA14-1 might improve treatment outcome.     

Telomerase activity and Bcl-2 expression in human breast cancer.

AIMS: Telomerase is a ribonucleoprotein that synthesizes telomeres and plays an important role in cellular immortalization. Bcl-2 gene encodes for a mitochondrial protein thought to prevent apoptosis of normal cells. We previously reported telomerase activity in 74% of human invasive breast cancers and detected a significant association between telomerase activity and prognostic parameters such as nodal status, tumour size and cellular proliferation. We hypothesized that telomerase reactivation in human breast cancer was associated with increased immunohistochemical expression of Bcl-2. METHODS: Bcl-2 immunohistochemical expression was determined in 25 infiltrating breast carcinomas with known telomerase activity (17 telomerase-positive and 8 telomerase-negative). The percentage of strongly and moderately stained tumour cells for Bcl-2 was determined by a breast pathologist who was blinded to telomerase data. Fisher's exact test was used to examine the association between telomerase activity and Bcl-2 expression. RESULTS: The median percentage of strongly stained tumour cells was 50% for telomerase-positive tumours (range, 0--100%) and 45% for telomerase-negative tumours (range, 0--100%). Twelve (70%) of 17 telomerase-positive tumours expressed strong or moderate Bcl-2 staining in >50% of tumour cells compared with six (75%) of eight telomerase-negative tumours (P=1.0). CONCLUSION: Telomerase reactivation seems to be independent of Bcl-2 protein expression in human breast cancer.     

Modulation of tamoxifen sensitivity by antisense Bcl-2 and trastuzumab in breast carcinoma cells

BACKGROUND: Because the overexpression of HER-2 and Bcl-2 is associated with resistance to tamoxifen (TAM), the authors examined the effect of antisense (AS) Bcl-2 on sensitivity to TAM compared with the effect of trastuzumab on sensitivity to TAM in breast carcinoma cell lines. METHODS: Drug sensitivity was assessed in vitro using a [3-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay with the breast carcinoma cell lines ZR-75-1, MDA-MB-453, and BT-474. AS Bcl-2 18-mer phosphorothioate oligonucleotide was applied. Apoptotic cell death was assessed with the terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick-end labeling method, and gene expression was evaluated with Western blot analysis. RESULTS: The expression of Bcl-2 was identified in ZR-75-1 and BT-474 cells and, to a lesser extent, in MDA-MB-453 cells. Overexpression of HER-2 was identified in BT-474 cells, and moderate expression was identified in MDA-MB-453 and ZR-75-1 cells. Combination treatment with trastuzumab or AS Bcl-2 enhanced TAM sensitivity in ZR-75-1 cells, which showed 50% inhibitory concentration (IC50) values of 0.9 microM (7.2-fold increase) and 0.5 microM (13.0-fold), respectively. Combination treatment with trastuzumab or AS Bcl-2 slightly enhanced TAM sensitivity of BT-474 cells, with IC50 values of 3.0 microM (1.3-fold) and 1.5 microM (2.6-fold), respectively. The sensitivity of MDA-MB-453 cells to TAM was not enhanced by combination with trastuzumab or AS Bcl-2. Modulation of TAM sensitivity by AS Bcl-2 was superior to modulation by trastuzumab in HER-2-expressing and Bcl-2-expressing breast carcinoma cells. Enhanced sensitivity in combination with AS Bcl-2 was associated with down-regulation of Bcl-2 and pAkt, which was correlated with the induction of Bax and caspase-3, leading to apoptosis. CONCLUSIONS: AS Bcl-2 appeared to be superior to trastuzumab with respect to regulating the signal-transduction pathways involved in breast carcinoma cells.     

Expression and tyrosine phosphorylation of EMS1 in human breast cancer cell lines

The EMS1 gene encodes an 80/85 kDa c-src substrate and localises with the CCND1 gene to chromosome 11q13. This locus is amplified in approximately 13% of human breast cancers. EMS1 gene amplification and expression were characterised in a panel of human breast cancer cell lines to determine at what levels expression is regulated. The degree of tyrosine phosphorylation of EMS1 protein was also determined and compared with the activity of src-family kinases. The EMS1 gene was amplified in 6 of 20 cell lines investigated: MDA-MB-134, -157, -175, -453, ZR-75-1 and MCF-7. In the MDA-MB-157 and MCF-7 cell lines, EMS1 was amplified in the absence of CCND1 gene amplification. EMS1 protein levels were increased relative to normal breast epithelial cells in 6 cell lines (ZR-75-1, MDA-MB-134, -175, -453, MCF-7 and BT-474). Of these, BT-474 is the only cell line that does not exhibit EMS1 amplification or increased EMS1 mRNA levels. EMS1 tyrosine phosphorylation was 3-fold higher in BT-474 and T-47D cells, which exhibited relatively high total src activity coupled with expression of both c-fyn and c-yes, than in MDA-MB-453 cells, which expressed only c-yes. Our results therefore demonstrate gene amplification to be the predominant mechanism underlying EMS1 over-expression in human breast cancer cell lines and identify tyrosine phosphorylation as a further level at which regulation of this protein may be perturbed. © 1996 Wiley-Liss, Inc.     

HA14-1 selectively induces apoptosis in Bcl-2-overexpressing leukemia/lymphoma cells, and enhances cytarabine-induced cell death.

The Bcl-2 oncoprotein is commonly overexpressed in hematological malignancy, where it promotes the survival of neoplastic cells. Recently, a small molecule (HA14-1) was reported to bind the surface pocket of Bcl-2 that mediates antiapoptotic interactions, triggering apoptosis in a Bcl-2-transfected cell line. We investigated the activity of this compound in a panel of malignant hematopoietic cell lines. Consistent with its proposed role as a Bcl-2 inhibitor, HA14-1 was most cytotoxic in lines expressing high levels of Bcl-2. In addition, at lower concentrations (5-12.5 muM), the compound predominantly triggered apoptosis. However, at concentrations two-fold higher than this and above, increasing primary necrosis was observed, suggesting the onset of interactions supplementary to Bcl-2 inhibition. In experiments on primary cells, 25 muM HA14-1 induced extensive apoptosis in acute leukemic blasts, but also suppressed normal hematopoietic colony formation to <50% of baseline. Importantly, low-concentration HA14-1 (5 muM) was nontoxic to normal colony-forming cells, whereas it enhanced the cytotoxicity of the antileukemia drug cytarabine in Bcl-2-positive lymphoblastic leukemia cells. In conclusion, our results indicate that HA14-1 at low concentration selectively triggers apoptosis in malignant hematopoietic cells that overexpress Bcl-2. Agents of this class may have particular utility in combination with cytotoxic chemotherapy drugs.     

Bcl-2 expression and triple negative profile in breast carcinoma

Many biomarkers for breast cancer prognosis have been proposed during the last two decades, among which HER2 and oestrogen receptors are of common use in routine clinical practice. However, in recent years, BCL2 has been recognized as an important prognostic parameter in human breast cancer, although its clinical utility is well established. The aim of this study was to examine the protein expression patterns of BCL2, HER2, oestrogen (ER) and progesterone receptors (PR) and to evaluate their correlation with survival and other prognostic parameters such as tumour size, histological grade and metastasis. We used a retrospective study including 84 Tunisian women with breast cancer. Immunohistochemistry was used to measure protein expression levels of several biomarkers. Association with conventional biopathological factors was analysed by SPSS (version13). The expression rates of BCL2, HER2, ER and PR were, respectively, 69, 62, 58.3 and 51.2%. In univariate analyses, BCL2 was highly correlated with both PR (P < 0.001) and ER (P = 0.006) and also with HER2 expression (P = 0.001). The triple negative profile showed a significant association with SBR (P = 0.016) and BCL2 expression (P = 0.02). In multivariate analyses, a significant association was maintained between BCL2 and both PR and ER (P = 0.02 and P = 0.004, respectively). Survival analysis showed that BCL2 expression was positively correlated with patients survival (P = 0.032). A Bayesian network analysis of all the variables confirmed the high value of BCL2 expression as a predictor of survival. As conclusion, BCL2 expression seems to be a very useful factor that should be in combination with HER2 and ER in breast cancer prognosis.