PMAIP1; phorbol-12-myristate-13-acetate-induced protein 1 (18q21.32)

Gene Summary

Gene:PMAIP1; phorbol-12-myristate-13-acetate-induced protein 1
Aliases: APR, NOXA
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:phorbol-12-myristate-13-acetate-induced protein 1
Updated:14 December, 2014


What does this gene/protein do?
Show (34)

Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 14 December 2014 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Boronic Acids
  • Transfection
  • Myeloid Cell Leukemia Sequence 1 Protein
  • Leukemic Gene Expression Regulation
  • Cancer Gene Expression Regulation
  • Promoter Regions
  • Piperazines
  • Cell Survival
  • Breast Cancer
  • Mutation
  • Gene Expression Profiling
  • Drug Synergism
  • Proto-Oncogene Proteins
  • Antineoplastic Agents
  • Nitrophenols
  • Nuclear Proteins
  • Mitochondria
  • Dose-Response Relationship, Drug
  • Membrane Proteins
  • Cell Proliferation
  • RNA Interference
  • Apoptosis Regulatory Proteins
  • Down-Regulation
  • Oligonucleotide Array Sequence Analysis
  • Tumor Markers
  • Phosphorylation
  • Risk Factors
  • Chronic Lymphocytic Leukemia
  • Chromosome 1
  • siRNA
  • Neoplasm Proteins
  • Western Blotting
  • Gene Expression
  • PMAIP1
  • Signal Transduction
  • Translocation
  • DNA-Binding Proteins
  • Pyrazines
  • Drug Resistance
  • Apoptosis
Tag cloud generated 14 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (2)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Chronic Lymphocytic LeukemiaPMAIP1 and Chronic Lymphocytic Leukemia View Publications13
Breast CancerPMAIP1 and Breast Cancer View Publications9

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Related Links

Latest Publications: PMAIP1 (cancer-related)

Tessoulin B, Descamps G, Moreau P, et al.
PRIMA-1Met induces myeloma cell death independent of p53 by impairing the GSH/ROS balance.
Blood. 2014; 124(10):1626-36 [PubMed] Related Publications
The aim of this study was to assess the efficiency of p53 reactivation and induction of massive apoptosis (PRIMA-1(Met)) in inducing myeloma cell death, using 27 human myeloma cell lines (HMCLs) and 23 primary samples. Measuring the lethal dose (LD50) of HMCLs revealed that HMCLs displayed heterogeneous sensitivity, with an LD50 ranging from 4 μM to more than 200 μM. The sensitivity of HMCLs did not correlate with myeloma genomic heterogeneity or TP53 status, and PRIMA-1(Met) did not induce or increase expression of the p53 target genes CDKN1A or TNFRSF10B/DR5. However, PRIMA-1(Met) increased expression of NOXA in a p53-independent manner, and NOXA silencing decreased PRIMA1(Met)-induced cell death. PRIMA-1(Met) depleted glutathione (GSH) content and induced reactive oxygen species production. The expression of GSH synthetase correlated with PRIMA-1(Met) LD50 values, and we showed that a GSH decrease mediated by GSH synthetase silencing or by and L-buthionine sulphoximine, an irreversible inhibitor of γ-glutamylcysteine synthetase, increased PRIMA-1(Met)-induced cell death and overcame PRIMA-1(Met) resistance. PRIMA-1(Met) (10 μM) induced cell death in 65% of primary cells independent of the presence of del17p; did not increase DR5 expression, arguing against an activation of p53 pathway; and synergized with L-buthionine sulphoximine in all samples. Finally, we showed in mouse TP53(neg) JJN3-xenograft model that PRIMA-1(Met) inhibited myeloma growth and synergized with L-buthionine sulphoximine in vivo.

Related: Apoptosis Myeloma Myeloma - Molecular Biology Signal Transduction TP53

Yun HS, Baek JH, Yim JH, et al.
Knockdown of hepatoma-derived growth factor-related protein-3 induces apoptosis of H1299 cells via ROS-dependent and p53-independent NF-κB activation.
Biochem Biophys Res Commun. 2014; 449(4):471-6 [PubMed] Related Publications
We previously identified hepatoma-derived growth factor-related protein-3 (HRP-3) as a radioresistant biomarker in p53 wild-type A549 cells and found that p53-dependent induction of the PUMA pathway was a critical event in regulating the radioresistant phenotype. Here, we found that HRP-3 knockdown regulates the radioresistance of p53-null H1299 cells through a distinctly different molecular mechanism. HRP-3 depletion was sufficient to cause apoptosis of H1299 cells by generating substantial levels of reactive oxygen species (ROS) through inhibition of the Nrf2/HO-1 antioxidant pathway. Subsequent, ROS-dependent and p53-independent NF-κB activation stimulated expression of c-Myc and Noxa proteins, thereby inducing the apoptotic machinery. Our results thus extend the range of targets for the development of new drugs to treat both p53 wild-type or p53-null radioresistant lung cancer cells.

Related: Apoptosis Lung Cancer TP53

Li L, Wang M, Yu G, et al.
Overactivated neddylation pathway as a therapeutic target in lung cancer.
J Natl Cancer Inst. 2014; 106(6):dju083 [PubMed] Related Publications
BACKGROUND: A number of oncoproteins and tumor suppressors are known to be neddylated, but whether the neddylation pathway is entirely activated in human cancer remains unexplored.
METHODS: NEDD8-activating enzyme (NAE) (E1) and NEDD8-conjugating enzyme (E2) expression and global-protein neddylation were examined by immunohistochemistry, immunoblotting, and real-time polymerase chain reaction analysis. Cell proliferation, clonogenic survival, migration, and motility in vitro, as well as tumor formation and metastasis in vivo, were determined upon neddylation inhibition by MLN4924, an investigational NEDD8-activating enzyme inhibitor. Survival was analyzed with Kaplan-Meier methods and compared by the log-rank test. All statistical tests were two-sided.
RESULTS: The entire neddylation pathway, including NEDD8-activating enzyme E1, NEDD8-conjugating enzyme E2, and global-protein neddylation, is overactivated in both lung adenocarcinoma and squamous-cell carcinoma. Compared with lung adenocarcinoma patients with low expression, those with high expression had worse overall survival (NEDD8-activating enzyme E1 subunit 1 [NAE1]: hazard ratio [HR] = 2.07, 95% confidence interval [CI] = 0.95 to 4.52, P = .07; ubiquitin-conjugating enzyme E2M (UBC12): HR = 13.26, 95% CI = 1.77 to 99.35, P = .01; global protein neddylation: HR = 3.74, 95% CI = 1.65 to 8.47, P = .002). Moreover, inhibition of neddylation by the NAE inhibitor MLN4924 statistically significantly suppressed proliferation, survival, migration, and motility of lung cancer cells in vitro and tumor formation and metastasis in vivo. At the molecular level, MLN4924 inactivated Cullin-RING E3 ligases, led to accumulation of tumor-suppressive Cullin-RING E3 ligase substrates and induced phorbol-12-myristate-13-acetate-induced protein 1 (NOXA)-dependent apoptosis or cellular senescence.
CONCLUSIONS: Our study highlights the overactivated neddylation pathway in lung cancer development and as a promising therapeutic target.

Related: Lung Cancer Signal Transduction

Kaku Y, Nagaya H, Tsuchiya A, et al.
Newly synthesized anticancer drug HUHS1015 is effective on malignant pleural mesothelioma.
Cancer Sci. 2014; 105(7):883-9 [PubMed] Related Publications
The newly synthesized naftopidil analogue HUHS1015 reduced cell viability in malignant pleural mesothelioma cell lines MSTO-211H, NCI-H28, NCI-H2052, and NCI-H2452, with the potential greater than that for the anticancer drugs paclitaxel or cisplatin at concentrations higher than 30 μM. HUHS1015 induced both necrosis and apoptosis of MSTO-211H and NCI-H2052 cells. HUHS1015 upregulated expression of mRNAs for Puma, Hrk, and Noxa in MSTO-211H and NCI-H2052 cells, suggesting HUHS1015-induced mitochondrial apoptosis. HUHS1015 clearly suppressed tumor growth in mice inoculated with NCI-H2052 cells. Taken together, the results of the present study indicate that HUHS1015 could be developed as an effective anticancer drug for treatment of malignant pleural mesothelioma.

Related: Apoptosis Lung Cancer Mesothelioma

Zhou P, Ma X, Iyer L, et al.
One siRNA pool targeting the λ constant region stops λ light-chain production and causes terminal endoplasmic reticulum stress.
Blood. 2014; 123(22):3440-51 [PubMed] Related Publications
In systemic light-chain amyloidosis, λ light chains produced by clonal plasma cells cause organ damage and early death. In pursuit of novel therapy, we developed 1 pool of short interfering RNA (siRNA) targeting the constant region of λ light chains that substantially and promptly reduces λ-light-chain production and secretion by human plasma cells regardless of sequence diversity. In clones producing intact immunoglobulin G (IgG) λ antibodies (containing paired heavy and light chains), the secretion of intact antibodies is reduced, and all 3 branches of the unfolded protein response are activated by accumulation of unpaired IgG heavy chains in the endoplasmic reticulum (ER). Moreover, an ER stress response can then become terminal with effector caspase activity mediated in part by the transcription of the Bcl-2 homology 3 domain only family member NOXA. This pool of siRNA can be used to reduce pathological λ-light-chain production and cause apoptosis in human plasma cells making intact IgGλ antibodies.

Jebahi A, Villedieu M, Pétigny-Lechartier C, et al.
PI3K/mTOR dual inhibitor NVP-BEZ235 decreases Mcl-1 expression and sensitizes ovarian carcinoma cells to Bcl-xL-targeting strategies, provided that Bim expression is induced.
Cancer Lett. 2014; 348(1-2):38-49 [PubMed] Related Publications
We previously showed that Bcl-xL and Mcl-1 cooperatively protect platinum-resistant ovarian cancer cells from apoptosis. Here we assessed the anticancer potential of combining ABT-737-induced inhibition of Bcl-xL with Mcl-1 inhibition via PI3K/Akt/mTOR pathway disruption using NVP-BEZ235. NVP-BEZ235 inhibited cell proliferation without inducing apoptosis. It strongly repressed Mcl-1 expression and induced Puma expression in both cell lines tested while differentially modulating Bim between the two. Interestingly, NVP-BEZ235 efficiently sensitized ovarian carcinoma cells to ABT-737, provided that Bim expression was induced. Moreover, inhibiting the ERK1/2 pathway restored Bim expression and sensitized low Bim-expressing cancer cells to the BEZ235/ABT-737 treatment.

Related: Ovarian Cancer Signal Transduction MCL1

Wang G, Li Z, Zhao Q, et al.
LincRNA-p21 enhances the sensitivity of radiotherapy for human colorectal cancer by targeting the Wnt/β-catenin signaling pathway.
Oncol Rep. 2014; 31(4):1839-45 [PubMed] Related Publications
Recent studies show that long intergenic noncoding RNA-p21 (lincRNA-p21) is aberrantly expressed in several types of cancer, including colorectal cancer (CRC), one of the most common cancers in the world. Radiotherapy is considered as a standard preoperative treatment approach to reduce local recurrence for local advanced rectal cancer. However, a considerable number of rectal cancers are resistant to radiotherapy. In the present study, we evaluated the role of lincRNA‑p21 in radiotherapy for CRC and detected the possible molecular mechanism. By expression profile analysis, we demonstrated that lincRNA-p21 decreases in CRC cell lines and tissue samples, which contributes to the elevation of β-catenin in CRC. We further showed that lincRNA‑p21 increases following X-ray treatment, and enforced expression of the lincRNA enhances the sensitivity of radiotherapy for CRC by promoting cell apoptosis. Suppression of the β-catenin signaling pathway and elevation of the pro-apoptosis gene Noxa expression may help explain the role of lincRNA-p21 in CRC radiotherapy. The present study not only deepens our understanding of the mechanism of radiotherapy for CRC, but it also provides a potential target for CRC radiotherapy.

Related: Apoptosis Colorectal (Bowel) Cancer

Dengler MA, Weilbacher A, Gutekunst M, et al.
Discrepant NOXA (PMAIP1) transcript and NOXA protein levels: a potential Achilles' heel in mantle cell lymphoma.
Cell Death Dis. 2014; 5:e1013 [PubMed] Free Access to Full Article Related Publications
Mantle cell lymphoma (MCL) is an aggressive lymphoid neoplasm with transient response to conventional chemotherapy. We here investigated the role of the Bcl-2 homology domain 3-only protein NOXA for life-death decision in MCL. Surprisingly, NOXA (PMAIP1) mRNA and NOXA protein levels were extremely discrepant in MCL cells: NOXA mRNA was found to be highly expressed whereas NOXA protein levels were low. Chronic active B-cell receptor signaling and to a minor degree cyclin D1 overexpression contributed to high NOXA mRNA expression levels in MCL cells. The phoshatidyl-inositol-3 kinase/AKT/mammalian target of rapamycin pathway was identified as the major downstream signaling pathway involved in the maintenance of NOXA gene expression. Interestingly, MCL cells adapt to this constitutive pro-apoptotic signal by extensive ubiquitination and rapid proteasomal degradation of NOXA protein (T½∼15-30 min). In addition to the proteasome inhibitor Bortezomib, we identified the neddylation inhibitor MLN4924 and the fatty acid synthase inhibitor Orlistat as potent inducers of NOXA protein expression leading to apoptosis in MCL. All inhibitors targeted NOXA protein turnover. In contrast to Bortezomib, MLN4924 and Orlistat interfered with the ubiquitination process of NOXA protein thereby offering new strategies to kill Bortezomib-resistant MCL cells. Our data, therefore, highlight a critical role of NOXA in the balance between life and death in MCL. The discrepancy between NOXA transcript and protein levels is essential for sensitivity of MCL to ubiquitin-proteasome system inhibitors and could therefore provide a druggable Achilles' heel of MCL cells.

Related: Apoptosis Mantle Cell Lymphoma AKT1 Signal Transduction

Li H, Tan M, Jia L, et al.
Inactivation of SAG/RBX2 E3 ubiquitin ligase suppresses KrasG12D-driven lung tumorigenesis.
J Clin Invest. 2014; 124(2):835-46 [PubMed] Free Access to Full Article Related Publications
Cullin-RING ligases (CRLs) are a family of E3 ubiquitin ligase complexes that rely on either RING-box 1 (RBX1) or sensitive to apoptosis gene (SAG), also known as RBX2, for activity. RBX1 and SAG are both overexpressed in human lung cancer; however, their contribution to patient survival and lung tumorigenesis is unknown. Here, we report that overexpression of SAG, but not RBX1, correlates with poor patient prognosis and more advanced disease. We found that SAG is overexpressed in murine KrasG12D-driven lung tumors and that Sag deletion suppressed lung tumorigenesis and extended murine life span. Using cultured lung cancer cells, we showed that SAG knockdown suppressed growth and survival, inactivated both NF-κB and mTOR pathways, and resulted in accumulation of tumor suppressor substrates, including p21, p27, NOXA, and BIM. Importantly, growth suppression by SAG knockdown was partially rescued by simultaneous knockdown of p21 or the mTOR inhibitor DEPTOR. Treatment with MLN4924, a small molecule inhibitor of CRL E3s, also inhibited the formation of KrasG12D-induced lung tumors through a similar mechanism involving inactivation of NF-κB and mTOR and accumulation of tumor suppressor substrates. Together, our results demonstrate that Sag is a Kras-cooperating oncogene that promotes lung tumorigenesis and suggest that targeting SAG-CRL E3 ligases may be an effective therapeutic approach for Kras-driven lung cancers.

Related: Lung Cancer KRAS gene

Angus L, van der Watt PJ, Leaner VD
Inhibition of the nuclear transporter, Kpnβ1, results in prolonged mitotic arrest and activation of the intrinsic apoptotic pathway in cervical cancer cells.
Carcinogenesis. 2014; 35(5):1121-31 [PubMed] Related Publications
The karyopherin β proteins are involved in nuclear-cytoplasmic trafficking and are crucial for protein and RNA subcellular localization. We previously showed that Kpnβ1, a nuclear importin protein, is overexpressed in cervical cancer and is critical for cervical cancer cell survival and proliferation, whereas non-cancer cells are less dependent on its expression. This study aimed to identify the mechanisms by which inhibition of Kpnβ1 results in cervical cancer cell death. We show that the inhibition of Kpnβ1 results in the induction of apoptosis and a prolonged mitotic arrest, accompanied by distinct mitotic defects in cervical cancer cells but not non-cancer cells. In cervical cancer cells, Kpnβ1 downregulation results in sustained degradation of the antiapoptotic protein, Mcl-1, and elevated Noxa expression, as well as mitochondrial membrane permeabilization resulting in the release of cytochrome C and activation of associated caspases. Although p53 becomes stabilized in Kpnβ1 knockdown cervical cancer cells, apoptosis occurs in a p53-independent manner. These results demonstrate that blocking Kpnβ1 has potential as an anticancer therapeutic approach.

Related: Apoptosis Signal Transduction TP53 Cervical Cancer

Zhao X, Liu X, Su L
Parthenolide induces apoptosis via TNFRSF10B and PMAIP1 pathways in human lung cancer cells.
J Exp Clin Cancer Res. 2014; 33:3 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Parthenolide (PTL) is a sesquiterpene lactone which can induce apoptosis in cancer cells and eradicate cancer stem cells such as leukemia stem cells, prostate tumor-initiating cells and so on. However, the mechanism remains largely unclear.
METHODS: Lung cancer cells were treated with parthenolide and the cell lysates were prepared to detect the given proteins by Western Blot analysis, and the cell survival was assayed by SRB and MTT assay. Cell cycle was evaluated by DNA flow cytometry analysis. TNFRSF10B, PMAIP1, ATF4 and DDIT3 genes were knocked down by siRNA technique. Apoptosis was evaluated by using Annexin V-FITC/PI staining and flow cytometry analysis.
RESULTS: Parthenolide (PTL) induces apoptosis and cell cycle arrest in human lung cancer cells. Moreover, PTL treatment in NSCLC cells increases expression of TNFRSF10B/DR5 and PMAIP1/NOXA. Silencing of TNFRSF10B or PMAIP1 or overexpression of CFLAR /c-FLIP (long form) could protect cells from PTL-induced apoptosis. Furthermore, PTL could increase the levels of endoplasmic reticulum stress hallmarks such as ERN1, HSPA5, p-EIF2A, ATF4 and DDIT3. Knockdown of ATF4 and DDIT3 abrogated PTL-induced apoptosis, which suggested that PTL induced apoptosis in NSCLC cells through activation of endoplasmic reticulum stress pathway. More importantly, we found that ATF4, DDIT3, TNFRSF10B and PMAIP1 were up-regulated more intensively, while CFLAR and MCL1 were down-regulated more dramatically by PTL in A549/shCDH1 cells than that in control cells, suggesting that PTL preferred to kill cancer stem cell-like cells by activating more intensive ER stress response in cancer stem cell-like cells.
CONCLUSION: We showed that parthenolide not only triggered extrinsic apoptosis by up-regulating TNFRSF10B and down-regulating CFLAR, but also induced intrinsic apoptosis through increasing the expression of PMAIP1 and decreasing the level of MCL1 in NSCLC cells. In addition, parthenolide triggered stronger ER stress response in cancer stem cell-like cells which leads to its preference in apoptotic induction. In summary, PTL induces apoptosis in NSCLC cells by activating endoplasmic reticulum stress response.

Related: Apoptosis CASP8 Lung Cancer Risk Factors and Prevention of Lung Cancer DDIT3 gene MCL1 TNFRSF10B

Hoffmann G, Breitenbücher F, Schuler M, Ehrenhofer-Murray AE
A novel sirtuin 2 (SIRT2) inhibitor with p53-dependent pro-apoptotic activity in non-small cell lung cancer.
J Biol Chem. 2014; 289(8):5208-16 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Sirtuin 2 (SIRT2) is an NAD(+)-dependent protein deacetylase whose targets include histone H4 lysine 16, p53, and α-tubulin. Because deacetylation of p53 regulates its effect on apoptosis, pharmacological inhibition of SIRT2-dependent p53 deacetylation is of great therapeutic interest for the treatment of cancer. Here, we have identified two structurally related compounds, AEM1 and AEM2, which are selective inhibitors of SIRT2 (IC50 values of 18.5 and 3.8 μM, respectively), but show only weak effects on other sirtuins such as SIRT1, SIRT3, and yeast Sir2. Interestingly, both compounds sensitized non-small cell lung cancer cell lines toward the induction of apoptosis by the DNA-damaging agent etoposide. Importantly, this sensitization was dependent on the presence of functional p53, thus establishing a link between SIRT2 inhibition by these compounds and p53 activation. Further, treatment with AEM1 and AEM2 led to elevated levels of p53 acetylation and to increased expression of CDKN1A, which encodes the cell cycle regulator p21(WAF1), as well as the pro-apoptotic genes PUMA and NOXA, three transcriptional targets of p53. Altogether, our data suggest that inhibition of SIRT2 by these compounds causes increased activation of p53 by decreasing SIRT2-dependent p53 deacetylation. These compounds thus provide a good opportunity for lead optimization and drug development to target p53-proficient cancers.

Related: Apoptosis Non-Small Cell Lung Cancer Etoposide Lung Cancer TP53

Chen DB, Cao K, Yang J, et al.
[Apoptosis of A549 cells induced by cloned Noxa gene].
Sichuan Da Xue Xue Bao Yi Xue Ban. 2013; 44(5):713-6, 726 [PubMed] Related Publications
OBJECTIVE: To clone the Noxa gene and to observe the apoptosis of A549 cells transfected with the recombinant plasmid of pcDNA-Noxa.
METHODS: The Noxa gene was obtained by PCR, and was cloned into pcDNA3. 1(-). A549 cells were transfected with the recombinant plasmid of pcDNA-Noxa. Western blot analysis was performed to determine the overexpression of Noxa. A549 cells were stained with Hoechst 33258 to observe the apoptosis.
RESULTS: The recombinant plasmid of pcDNA-Noxa was successfully constructed evidenced by endonuclease digestion and sequence analysis. The overexpression of Noxa was identified using Western blot analysis. The recombinant plasmid of pcDNA-Noxa induced apoptosis of A549 cells.
CONCLUSION: Nora has exhibited potential pro-apoptotic activity against A549 cells. This study is a foundation for further research into pro-apoptotic activity of Noxa gene.

Related: Apoptosis Lung Cancer

Lee YJ, Park IS, Lee YJ, et al.
Resveratrol contributes to chemosensitivity of malignant mesothelioma cells with activation of p53.
Food Chem Toxicol. 2014; 63:153-60 [PubMed] Related Publications
Resveratrol is a naturally occurring polyphenolic phytoalexin with chemopreventive properties. We previously reported a synergistic anti-proliferative effect of resveratrol and clofarabine against malignant mesothelioma (MM) cells. Here, we further investigated molecular mechanisms involved in the synergistic interaction of these compounds in MM MSTO-211H cells. Resveratrol, in combination with clofarabine, time-dependently induced a strong cytotoxic effect with the nuclear accumulation of phospho-p53 (p-p53) in MSTO-211H cells, but not in normal mesothelial MeT-5A cells. Combination treatment up-regulated the levels of p-p53, cleaved caspase-3, and cleaved PARP proteins. Gene silencing with p53-targeting siRNA attenuated the sensitivity of cells to the combined treatment of two compounds. Analyses of p53 DNA binding assay, p53 reporter gene assay, and RTP-CR toward p53-regulated genes, including Bax, PUMA, Noxa and p21, demonstrated that induced p-p53 is transcriptionally active. These results were further confirmed by the siRNA-mediated knockdown of p53 gene. Combination treatment significantly caused the accumulation of cells at G1 phase with the increases in the sub-G0/G1 peak, DNA ladder, nuclear fragmentation, and caspase-3/7 activity. Taken together, these results demonstrate that resveratrol and clofarabine synergistically elicit apoptotic signal via a p53-dependent pathway, and provide a scientific rationale for clinical evaluation of resveratrol as a promising chemopotentiator in MM.

Related: Mesothelioma Clofarabine

Kater AP, Spiering M, Liu RD, et al.
Dasatinib in combination with fludarabine in patients with refractory chronic lymphocytic leukemia: a multicenter phase 2 study.
Leuk Res. 2014; 38(1):34-41 [PubMed] Related Publications
Resistance to chemotherapy-induced apoptosis in CLL is associated with overexpression of antiapoptotic proteins induced by signals from the microenvironment. In vitro, dasatinib effectively inhibits expression of anti-apoptotic regulators and restores fludarabine sensitivity in activated CLL. The aim of this study was to evaluate efficacy of one cycle of dasatinib monotherapy (100mg/day, days 1-28) followed by combination of dasatinib with fludarabine (40mg/m²/day, days 1-3 every 28 day) for a total of 6 cycles in fludarabine-refractory CLL. The primary endpoint was overall response rate according to the IWCLL'08 criteria. 20 patients were enrolled: 18 completed at least one cycle of treatment of which 67% finished at least 2 cycles of combination treatment. 3 of these 18 patients reached a formal PR (16.7%). Majority of patients obtained some reduction in lymph node (LN) size. Most frequent toxicity was related to myelosuppression. NF-κB RNA expression levels of circulating CLL cells decreased whereas the levels of pro-apoptotic NOXA increased during treatment. In conclusion, dasatinib/fludarabine combination has modest clinical efficacy in fludarabine-refractory patients.

Related: Chronic Lymphocytic Leukemia (CLL) CLL - Molecular Biology Fludarabine Dasatinib (Sprycel)

Gu J, Tang Y, Liu Y, et al.
Murine double minute 2 siRNA and wild-type p53 gene therapy enhances sensitivity of the SKOV3/DDP ovarian cancer cell line to cisplatin chemotherapy in vitro and in vivo.
Cancer Lett. 2014; 343(2):200-9 [PubMed] Related Publications
SKOV3/DDP cells urgently require an efficient therapy to improve drug resistance. Here we show a critical role for cisplatin combined with gene therapy, using transfection of a p53 gene/MDM2-siRNA plasmid, in improving cisplatin sensitivity of SKOV3/DDP cells with a strong inhibition of tumor cell growth in vitro and in vivo. The effects may be associated with enhancement of intracellular platinum accumulation via decreased MDR1/P-gp and improvement of apoptotic resistance via increased P53, PUMA and NOXA expression. The combined therapy may efficiently inhibit cell invasion and migration via deceased HIF-1, VEGF, MMP-9 and MMP-2 to suppress malignant progression. These results indicate that cisplatin chemotherapy combined with targeting the MDM2/p53 axis is an attractive strategy to treat SKOV3/DDP cancer.

Related: Cisplatin Ovarian Cancer TP53

Aryee DN, Niedan S, Ban J, et al.
Variability in functional p53 reactivation by PRIMA-1(Met)/APR-246 in Ewing sarcoma.
Br J Cancer. 2013; 109(10):2696-704 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
BACKGROUND: Though p53 mutations are rare in ES, there is a strong indication that p53 mutant tumours form a particularly bad prognostic group. As such, novel treatment strategies are warranted that would specifically target and eradicate tumour cells containing mutant p53 in this subset of ES patients.
METHODS: PRIMA-1(Met), also known as APR-246, is a small organic molecule that has been shown to restore tumour-suppressor function primarily to mutant p53 and also to induce cell death in various cancer types. In this study, we interrogated the ability of APR-246 to induce apoptosis and inhibit tumour growth in ES cells with different p53 mutations.
RESULTS: APR-246 variably induced apoptosis, associated with Noxa, Puma or p21(WAF1) upregulation, in both mutant and wild-type p53 harbouring cells. The apoptosis-inducing capability of APR-246 was markedly reduced in ES cell lines transfected with p53 siRNA. Three ES cell lines established from the same patient at different stages of the disease and two cell lines of different patients with identical p53 mutations all exhibited different sensitivities to APR-246, indicating cellular context dependency. Comparative transcriptome analysis on the three cell lines established from the same patient identified differential expression levels of several TP53 and apoptosis-associated genes such as APOL6, PENK, PCDH7 and MST4 in the APR-246-sensitive cell line relative to the less APR-246-sensitive cell lines.
CONCLUSION: This is the first study reporting the biological response of Ewing sarcoma cells to APR-246 exposure and shows gross variability in responses. Our study also proposes candidate genes whose expression might be associated with ES cells' sensitivity to APR-246. With APR-246 currently in early-phase clinical trials, our findings call for caution in considering it as a potential adjuvant to conventional ES-specific chemotherapeutics.

Related: Apoptosis Bone Cancers Ewing's Sarcoma TP53

Humphries LA, Godbersen JC, Danilova OV, et al.
Pro-apoptotic TP53 homolog TAp63 is repressed via epigenetic silencing and B-cell receptor signalling in chronic lymphocytic leukaemia.
Br J Haematol. 2013; 163(5):590-602 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Chronic lymphocytic leukaemia (CLL) is an accumulative disorder marked by deficient apoptosis. The TP53 homolog TAp63 promotes apoptosis and chemosensitivity in solid tumours and its deregulation may contribute to CLL cell survival. We found that TAp63α was the most prevalent TP63 isoform in CLL. Compared to healthy B cells, TAp63 mRNA was repressed in 55·7% of CLL samples. TP63 promoter methylation was high in CLL and inversely correlated with TP63 protein expression in B-cell lymphoma cell lines. siRNA-mediated knockdown of TP63 resulted in partial protection from spontaneous apoptosis accompanied by reductions in PMAIP1 (NOXA), BBC3 (PUMA), and BAX mRNA in CLL cells and increased proliferation of Raji lymphoma cells. TAp63 mRNA levels were higher in CLL with unmutated IGHV. B-cell receptor (BCR) engagement led to repression of TP63 mRNA expression in malignant B cells, while pharmacological inhibition of BCR signalling prevented TP63 downregulation. MIR21, known to target TAp63, correlated inversely with TAp63 expression in CLL, and BCR-mediated downregulation of TP63 was accompanied by MIR21 upregulation in most CLL samples. Our data illustrate the pro-apoptotic function of TP63, provide insights into the mechanisms of BCR-targeting agents, and establish a rationale for designing novel approaches to induce TP63 in CLL and B-cell lymphoma.

Related: Apoptosis Chronic Lymphocytic Leukemia (CLL) CLL - Molecular Biology miR-21

Koster R, van Vugt MA, Timmer-Bosscha H, et al.
Unravelling mechanisms of cisplatin sensitivity and resistance in testicular cancer.
Expert Rev Mol Med. 2013; 15:e12 [PubMed] Related Publications
Testicular cancer is the most frequent solid malignant tumour type in men 20-40 years of age. At the time of diagnosis up to 50% of the patients suffer from metastatic disease. In contrast to most other metastatic solid tumours, the majority of metastatic testicular cancer patients can be cured with highly effective cisplatin-based chemotherapy. This review aims to summarise the current knowledge on response to chemotherapy and the biological basis of cisplatin-induced apoptosis in testicular cancer. The frequent presence of wild-type TP53 and the low levels of p53 in complex with the p53 negative feed-back regulator MDM2 contribute to cisplatin sensitivity. Moreover, the high levels of the pluripotency regulator Oct4 and as a consequence of Oct4 expression high levels of miR-17/106b seed family and pro-apoptotic Noxa and the low levels of cytoplasmic p21 (WAF1/Cip1) appear to be causative for the exquisite sensitivity to cisplatin-based therapy of testicular cancer. However, resistance of testicular cancer to cisplatin-based therapy does occur and can be mediated through aberrant levels of the above mentioned key players. Drugs targeting these key players showed, at least pre-clinically, a sensitising effect to cisplatin treatment. Further clinical development of such treatment strategies will lead to new treatment options for platinum-resistant testicular cancers.

Related: Cisplatin Testicular Cancer

Peter B, Cerny-Reiterer S, Hadzijusufovic E, et al.
The pan-Bcl-2 blocker obatoclax promotes the expression of Puma, Noxa, and Bim mRNA and induces apoptosis in neoplastic mast cells.
J Leukoc Biol. 2014; 95(1):95-104 [PubMed] Related Publications
Advanced SM is an incurable neoplasm with short survival time. So far, no effective therapy is available for these patients. We and others have shown recently that neoplastic MC in ASM and MCL express antiapoptotic Mcl-1, Bcl-2, and Bcl-xL. In this study, we examined the effects of the pan-Bcl-2 family blocker obatoclax (GX015-070) on primary neoplastic MC, the human MC leukemia cell line HMC-1, and the canine mastocytoma cell line C2. Obatoclax was found to inhibit proliferation in primary human neoplastic MC (IC₅₀: 0.057 μM), in HMC-1.2 cells expressing KIT D816V (IC₅₀: 0.72 μM), and in HMC-1.1 cells lacking KIT D816V (IC₅₀: 0.09 μM), as well as in C2 cells (IC₅₀: 0.74 μM). The growth-inhibitory effects of obatoclax in HMC-1 cells were accompanied by an increase in expression of Puma, Noxa, and Bim mRNA, as well as by apoptosis, as evidenced by microscopy, TUNEL assay, and caspase cleavage. Viral-mediated overexpression of Mcl-1, Bcl-xL, or Bcl-2 in HMC-1 cells was found to introduce partial resistance against apoptosis-inducing effects of obatoclax. We were also able to show that obatoclax synergizes with several other antineoplastic drugs, including dasatinib, midostaurin, and bortezomib, in producing apoptosis and/or growth arrest in neoplastic MC. Together, obatoclax exerts major growth-inhibitory effects on neoplastic MC and potentiates the antineoplastic activity of other targeted drugs. Whether these drug effects can be translated to application in patients with advanced SM remains to be determined.

Related: Apoptosis MCL1

Saha MN, Jiang H, Yang Y, et al.
PRIMA-1Met/APR-246 displays high antitumor activity in multiple myeloma by induction of p73 and Noxa.
Mol Cancer Ther. 2013; 12(11):2331-41 [PubMed] Related Publications
Targeting p53 by the small-molecule PRIMA-1(Met)/APR-246 has shown promising preclinical activity in various cancer types. However, the mechanism of PRIMA-1(Met)-induced apoptosis is not completely understood and its effect on multiple myeloma cells is unknown. In this study, we evaluated antitumor effect of PRIMA-1(Met) alone or its combination with current antimyeloma agents in multiple myeloma cell lines, patient samples, and a mouse xenograft model. Results of our study showed that PRIMA-1(Met) decreased the viability of multiple myeloma cells irrespective of p53 status, with limited cytotoxicity toward normal hematopoietic cells. Treatment of multiple myeloma cells with PRIMA-1(Met) resulted in induction of apoptosis, inhibition of colony formation, and migration. PRIMA-1(Met) restored wild-type conformation of mutant p53 and induced activation of p73 upregulating Noxa and downregulating Mcl-1 without significant modulation of p53 level. siRNA-mediated silencing of p53 showed a little effect on apoptotic response of PRIMA-1(Met), whereas knockdown of p73 led to substantial attenuation of apoptotic activity in multiple myeloma cells, indicating that PRIMA-1(Met)-induced apoptosis is, at least in part, p73-dependent. Importantly, PRIMA-1(Met) delayed tumor growth and prolonged survival of mice bearing multiple myeloma tumor. Furthermore, combined treatment of PRIMA-1(Met) with dexamethasone or doxorubicin displayed synergistic effects in both multiple myeloma cell lines and primary multiple myeloma samples. Consistent with our in vitro observations, cotreatment with PRIMA-1(Met) and dexamethasone resulted in enhanced antitumor activity in vivo. Our study for the first time shows antimyeloma activity of PRIMA-1(Met) and provides the rationale for its clinical evaluation in patients with multiple myeloma, including the high-risk group with p53 mutation/deletion.

Related: Apoptosis Doxorubicin Myeloma Myeloma - Molecular Biology TP73

Cruickshanks N, Hamed HA, Booth L, et al.
Histone deacetylase inhibitors restore toxic BH3 domain protein expression in anoikis-resistant mammary and brain cancer stem cells, thereby enhancing the response to anti-ERBB1/ERBB2 therapy.
Cancer Biol Ther. 2013; 14(10):982-96 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
The present studies focused on defining the mechanisms by which anoikis-resistant (AR) mammary carcinoma cells can be reverted to a therapy-sensitive phenotype. AR mammary carcinoma cells had reduced expression of the toxic BH3 domain proteins BAX, BAK, NOXA, and PUMA. In AR cells expression of the protective BCL-2 family proteins BCL-XL and MCL-1 was increased. AR cells were resistant to cell killing by multiple anti-tumor cell therapies, including ERBB1/2 inhibitor + MCL-1 inhibitor treatment, and had a reduced autophagic flux response to these therapies, despite similarly exhibiting increased levels of LC3II processing. Knockdown of MCL-1 and BCL-XL caused necro-apoptosis in AR cells to a greater extent than in parental cells. Pre-treatment of anoikis-resistant cells with histone deacetylase inhibitors (HDACIs) for 24 h increased the levels of toxic BH3 domain proteins, reduced MCL-1 levels, and restored/re-sensitized the cell death response of AR tumor cells to multiple toxic therapies. In vivo, pre-treatment of AR breast tumors in the brain with valproate restored the chemo-sensitivity of the tumors and prolonged animal survival. These data argue that one mechanism to enhance the anti-tumor effect of chemotherapy could be HDACI pre-treatment.

Related: Breast Cancer BAK1 MCL1 Lapatinib (Tyverb) EGFR

Dabir S, Kluge A, McColl K, et al.
PIAS3 activates the intrinsic apoptotic pathway in non-small cell lung cancer cells independent of p53 status.
Int J Cancer. 2014; 134(5):1045-54 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Protein inhibitor of activated signal transducer and activator of transcription 3 (STAT3) (PIAS3) is an endogenous inhibitor of STAT3 that negatively regulates STAT3 transcriptional activity and cell growth and demonstrates limited expression in the majority of human squamous cell carcinomas of the lung. In this study, we sought to determine whether PIAS3 inhibits cell growth in non-small cell lung cancer cell lines by inducing apoptosis. Our results demonstrate that overexpression of PIAS3 promotes mitochondrial depolarization, leading to cytochrome c release, caspase 9 and 3 activation and poly (ADP-ribose) polymerase cleavage. This intrinsic pathway activation was associated with decreased Bcl-xL expression and increased Noxa expression and was independent of p53 status. Furthermore, PIAS3 inhibition of STAT3 activity was also p53 independent. Microarray experiments were performed to discover STAT3-independent mediators of PIAS3-induced apoptosis by comparing the apoptotic gene expression signature induced by PIAS3 overexpression with that induced by STAT3 siRNA. The results showed that a subset of apoptotic genes was uniquely expressed only after PIAS3 expression. Thus, PIAS3 may represent a promising lung cancer therapeutic target because of its p53-independent efficacy and its potential to synergize with Bcl-2 targeted inhibitors.

Related: Apoptosis Non-Small Cell Lung Cancer Lung Cancer TP53

Petrocca F, Altschuler G, Tan SM, et al.
A genome-wide siRNA screen identifies proteasome addiction as a vulnerability of basal-like triple-negative breast cancer cells.
Cancer Cell. 2013; 24(2):182-96 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Basal-like triple-negative breast cancers (TNBCs) have poor prognosis. To identify basal-like TNBC dependencies, a genome-wide siRNA lethality screen compared two human breast epithelial cell lines transformed with the same genes: basal-like BPLER and myoepithelial HMLER. Expression of the screen's 154 BPLER dependency genes correlated with poor prognosis in breast, but not lung or colon, cancer. Proteasome genes were overrepresented hits. Basal-like TNBC lines were selectively sensitive to proteasome inhibitor drugs relative to normal epithelial, luminal, and mesenchymal TNBC lines. Proteasome inhibition reduced growth of established basal-like TNBC tumors in mice and blocked tumor-initiating cell function and macrometastasis. Proteasome addiction in basal-like TNBCs was mediated by NOXA and linked to MCL-1 dependence.

Related: Breast Cancer

Lamy E, Hertrampf A, Herz C, et al.
Preclinical evaluation of 4-methylthiobutyl isothiocyanate on liver cancer and cancer stem cells with different p53 status.
PLoS One. 2013; 8(8):e70846 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Isothiocyanates from plants of the order Brassicales are considered promising cancer chemotherapeutic phytochemicals. However, their selective cytotoxicity on liver cancer has been barely researched. Therefore, in the present study, we systematically studied the chemotherapeutic potency of 4-methylthiobutyl isothiocyanate (MTBITC). Selective toxicity was investigated by comparing its effect on liver cancer cells and their chemoresistant subpopulations to normal primary hepatocytes and liver tissue slices. Additionally, in a first assessment, the in vivo tolerability of MTBITC was investigated in mice. Growth arrest at G2/M and apoptosis induction was evident in all in vitro cancer models treated with MTBITC, including populations with cancer initiating characteristics. This was found independent from TP53; however cell death was delayed in p53 compromised cells as compared to wt-p53 cells which was probably due to differential BH3 only gene regulation i. e. Noxa and its antagonist A1. In normal hepatocytes, no apoptosis or necrosis could be detected after repeated administration of up to 50 µM MTBITC. In mice, orally applied MTBITC was well tolerated over 18 days of treatment for up to 50 mg/kg/day, the highest dose tested. In conclusion, we could show here that the killing effect of MTBITC has a definite selectivity for cancer cells over normal liver cells and its cytotoxicity even applies for chemoresistant cancer initiating cells. Our study could serve for a better understanding of the chemotherapeutic properties of isothiocyanates on human liver-derived cancer cells.

Related: Apoptosis Liver Cancer Signal Transduction TP53

Lee HT, Choi MR, Doh MS, et al.
Effects of the monoamine oxidase inhibitors pargyline and tranylcypromine on cellular proliferation in human prostate cancer cells.
Oncol Rep. 2013; 30(4):1587-92 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Chemotherapy is one of the therapeutic strategies that has been used for the inhibition of cancer cell proliferation in several types of cancer, including prostate cancer. Although monoamine oxidase (MAO) inhibitors, phytoestrogen and antioxidants used in chemotherapy have been systematically studied, their effects on cancer cell growth remain to be fully understood. The purpose of this study was to investigate the effects of the MAO inhibitors, pargyline and tranylcypromine on cell survival in human prostate carcinoma (LNCaP-LN3) cells. After treating LNCaP-LN3 cells with pargyline or tranylcypromine, we examined cell proliferation, cell cycle pattern, apoptosis and the expression levels of apoptosis-related genes. The proliferation of cells exposed to pargyline decreased in a dose- and time-dependent manner, while tranylcypromine-treated cells showed the opposite results. Treatment with pargyline significantly induced cell cycle arrest at the G1 phase compared to the control and tranylcypromine-treated cells. In addition, pargyline induced an increase in the cell death rate by promoting apoptosis; however, tranylcypromine had no effect on LNCaP-LN3 cells. Based on our results, we suggest that pargyline is more powerful than tranylcypromine for the treatment of human prostate cancer.

Related: Apoptosis CASP3 Prostate Cancer

Chen C, Hu SY, Luo DQ, et al.
Potential antitumor agent from the endophytic fungus Pestalotiopsis photiniae induces apoptosis via the mitochondrial pathway in HeLa cells.
Oncol Rep. 2013; 30(4):1773-81 [PubMed] Related Publications
4-(3',3'-Dimethylallyloxy)-5-methyl-6-methoxy-phthalide (DMMP) has previously been isolated from the endophytic fungus Pestalotiopsis photiniae. Although the cytotoxic activities of DMMP have been reported, little is known concerning the molecular mechanism of its cytotoxic effect. In the present study, we investigated the effect of DMMP on the growth of several types of cancer cell lines and investigated the mechanism of its antiproliferative effect. DMMP caused the growth inhibition of human cancer lines HeLa, MCF7 and MDA-MB-231, but had little antiproliferative effect on MRC5 normal lung cells. DMMP also significantly caused cell cycle arrest in the G1 phase and upregulated the cyclin-dependent kinase inhibitor p27KIPI protein in the HeLa cells. Moreover DMMP was able to induce marked nuclear apoptotic morphology in HeLa cells. DMMP induced apoptosis and loss of mitochondrial membrane potential (ΔΨm) in the HeLa cells. Although the activated forms of caspase-9 and -3 in HeLa cells were detected, pretreatment with caspase inhibitors (Ac-DEVD-CHO and Z-VAD-FMK) failed to attenuate DMMP-induced cell death. In addition, protein levels of the p53 family members, p53 and p73, were upregulated, and DMMP significantly increased the mRNA expression of pro-apoptotic Bcl-2 family genes (PUMA, NOXA, Bax, Bad and Bim). HPV E6-E7 mRNA levels were reduced. In conclusion, DMMP demonstrates potential for use in the treatment of cervical cancer.

Related: Apoptosis CASP3 CDKN1B Mitochondrial Mutations in Cancer TP53 Cervical Cancer BAD TP73

Zekri A, Ghaffari SH, Yousefi M, et al.
Autocrine human growth hormone increases sensitivity of mammary carcinoma cell to arsenic trioxide-induced apoptosis.
Mol Cell Endocrinol. 2013; 377(1-2):84-92 [PubMed] Related Publications
Human growth hormone (hGH) has been increasingly implicated in a variety of cancers; its up-regulation is observed in breast cancer and correlates with a poor outcome. Autocrine hGH promotes mammary carcinoma cell survival, proliferation, immortalization; it confers an invasive phenotype as a result of an epithelial-mesenchymal transition and contributes to chemoresistance and radioresistance. Arsenic trioxide (ATO) is being successfully used as a first and second line therapy for the treatment of patients with acute promyelocytic leukemia. It also inhibits tumor cell growth and induces apoptosis in a broad range of solid tumors. In the present study, we investigated the effect of hGH on sensitivity of a mammary adenocarcinoma cell to ATO, using a stable hGH-transfectant MCF-7 cell line, MCF7-hGH. Our results demonstrated for the first time that the overexpression of hGH increased sensitivity of the breast cancer cell line MCF-7 to ATO through apoptotic and anti-proliferative mechanisms. The effect of ATO on the transcriptional level of genes involved in survival (Bcl-2, Bax and Survivin), self-sufficiency in growth signals (c-Myc, ARF, Cdc25A, p53 and Bax), immortalization (hTERT) and invasion and metastasis (MMP-2 and MMP-9, uPA and uPAR and E-cadherin) was more pronounced in MCF7-hGH compared with its parental MCF-7 line. Our study may highlight the potential application of ATO for the treatment of patients with breast cancer, especially in those who have metastatic and chemoresistant tumor phenotype possibly due to the over expression of hGH.

Related: Apoptosis Breast Cancer TP53

Yi YW, Kang HJ, Kim HJ, et al.
Targeting mutant p53 by a SIRT1 activator YK-3-237 inhibits the proliferation of triple-negative breast cancer cells.
Oncotarget. 2013; 4(7):984-94 [PubMed] Article available free on PMC after 21/02/2015 Related Publications
Many types of mutations in tumor suppressor p53 are oncogenic through gain-of-function. Therefore, targeting mutant p53 (mtp53) is a promising therapeutic approach to fight against many types of cancers. We report here a small molecule compound YK-3-237 that reduces acetylation of mtp53 and exhibits anti-proliferative effects toward triple-negative breast cancer (TNBC) cells carrying mtp53. YK-3-237 activates SIRT1 enzyme activities in vitro and deacetylation of both mtp53 in a SIRT1-dependent manner. Deacetylation of mtp53 resulted in depletion of mtp53 protein level and up-regulated the expression of WTp53-target genes, PUMA and NOXA. YK-3-237 also induces PARP-dependent apoptotic cell death and arrests the cell cycle at G2/M phase of mtp53 TNBC cells. Taken together, our data suggest that targeting acetylation of mtp53 is a potential target to treat human cancers.

Related: Apoptosis TP53

Hu J, Van Valckenborgh E, Xu D, et al.
Synergistic induction of apoptosis in multiple myeloma cells by bortezomib and hypoxia-activated prodrug TH-302, in vivo and in vitro.
Mol Cancer Ther. 2013; 12(9):1763-73 [PubMed] Related Publications
Recently, we showed that hypoxia is a critical microenvironmental factor in multiple myeloma, and that the hypoxia-activated prodrug TH-302 selectively targets hypoxic multiple myeloma cells and improves multiple disease parameters in vivo. To explore approaches for sensitizing multiple myeloma cells to TH-302, we evaluated in this study the antitumor effect of TH-302 in combination with the clinically used proteasome inhibitor bortezomib. First, we show that TH-302 and bortezomib synergistically induce apoptosis in multiple myeloma cell lines in vitro. Second, we confirm that this synergism is related to the activation of caspase cascades and is mediated by changes of Bcl-2 family proteins. The combination treatment induces enhanced cleavage of caspase-3/8/9 and PARP, and therefore triggers apoptosis and enhances the cleavage of proapoptotic BH3-only protein BAD and BID as well as the antiapoptotic protein Mcl-1. In particular, TH-302 can abrogate the accumulation of antiapoptotic Mcl-1 induced by bortezomib, and decreases the expression of the prosurvival proteins Bcl-2 and Bcl-xL. Furthermore, we found that the induction of the proapoptotic BH3-only proteins PUMA (p53-upregulated modulator of apoptosis) and NOXA is associated with this synergism. In response to the genotoxic and endoplasmic reticulum stresses by TH-302 and bortezomib, the expression of PUMA and NOXA were upregulated in p53-dependent and -independent manners. Finally, in the murine 5T33MMvv model, we showed that the combination of TH-302 and bortezomib can improve multiple disease parameters and significantly prolong the survival of diseased mice. In conclusion, our studies provide a rationale for clinical evaluation of the combination of TH-302 and bortezomib in patients with multiple myeloma.

Related: Apoptosis Myeloma Myeloma - Molecular Biology Signal Transduction Bortezomib


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