Constitutive activation of caspase-3 and Poly ADP ribose polymerase cleavage in fanconi anemia cells

p20BAP31 induces cell apoptosis via both AIF caspase-independent and the ROS/JNK mitochondrial pathway in colorectal cancer

Background

During cell apoptosis, the C-terminus of BAP31 is cleaved by caspase-8 and generates p20BAP31, which has been shown to induce an apoptotic pathway between the endoplasmic reticulum (ER) and mitochondria. However, the underlying mechanisms of p20BAP31 in cell apoptosis remains unclear.

Methods

We compared the effects of p20BAP31 on cell apoptosis in six cell lines and selected the most sensitive cells. Functional experiments were conducted, including Cell Counting Kit 8 (CCK-8), reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) assay. Then, cell cycle and apoptosis were investigated by flow cytometry and verified by immunoblotting. Next, NOX inhibitors (ML171 and apocynin), ROS scavenger (NAC), JNK inhibitor (SP600125), and caspase inhibitor (Z-VAD-FMK) were used to further investigate the underlying mechanisms of p20BAP31 on cell apoptosis. Finally, apoptosis-inducing factor (AIF) translocation from the mitochondria to the nuclei was verified by immunoblotting and immunofluorescence assay.

Results

We found that overexpression of p20BAP31 indeed induced apoptosis and had a much greater sensitivity in HCT116 cells. Furthermore, the overexpression of p20BAP31 inhibited cell proliferation by causing S phase arrest. Further study revealed that p20BAP31 reduced MMP, with a significant increase in ROS levels, accompanied by the activation of the MAPK signaling pathway. Importantly, the mechanistic investigation indicated that p20BAP31 induces mitochondrial-dependent apoptosis by activating the ROS/JNK signaling pathway and induces caspase-independent apoptosis by promoting the nuclear translocation of AIF.

Conclusions

p20BAP31 induced cell apoptosis via both the ROS/JNK mitochondrial pathway and AIF caspase-independent pathway. Compared with antitumor drugs that are susceptible to drug resistance, p20BAP31 has unique advantages for tumor therapy.

Apoptosis in megakaryocytes: Safeguard and threat for thrombopoiesis

Platelets, generated from precursor megakaryocytes (MKs), are central mediators of hemostasis and thrombosis. The process of thrombopoiesis is extremely complex, regulated by multiple factors, and related to many cellular events including apoptosis. However, the role of apoptosis in thrombopoiesis has been controversial for many years. Some researchers believe that apoptosis is an ally of thrombopoiesis and platelets production is apoptosis-dependent, while others have suggested that apoptosis is dispensable for thrombopoiesis, and is even inhibited during this process. In this review, we will focus on this conflict, discuss the relationship between megakaryocytopoiesis, thrombopoiesis and apoptosis. In addition, we also consider why such a vast number of studies draw opposite conclusions of the role of apoptosis in thrombopoiesis, and try to figure out the truth behind the mystery. This review provides more comprehensive insights into the relationship between megakaryocytopoiesis, thrombopoiesis, and apoptosis and finds some clues for the possible pathological mechanisms of platelet disorders caused by abnormal apoptosis.

Utility and Mechanism of SHetA2 and Paclitaxel for Treatment of Endometrial Cancer

Simple Summary

Incidence and death rates for endometrial cancer are steadily rising world-wide. Endometrial cancer patients at high risk for recurrence are treated with chemotherapy, which causes significant toxicity. Molecularly targeted drugs have been found to cause less toxicity than chemotherapy. We studied a low-toxicity drug, called SHetA2, which targets three heat shock A proteins that are highly mutated in endometrial cancers. Our results demonstrated that SHetA2 inhibits endometrial cancer cells and tumors, and enhances therapeutic effects of paclitaxel without increasing toxicity. This information supports development of clinical trials to test if combining SHetA2 with paclitaxel can increase the paclitaxel therapeutic effect without increasing toxicity, or allows a lowered paclitaxel dose to achieve the same level of therapeutic effect, but with reduced toxicity. Our new knowledge about how SHetA2 works can be translated into development of biomarkers to predict with patients would most likely benefit from SHetA2-based therapy.

Abstract

Endometrial cancer patients with advanced disease or high recurrence risk are treated with chemotherapy. Our objective was to evaluate the utility and mechanism of a novel drug, SHetA2, alone and in combination with paclitaxel, in endometrial cancer. SHetA2 targets the HSPA chaperone proteins, Grp78, hsc70, and mortalin, which have high mutation rates in endometrial cancer. SHetA2 effects on cancerous phenotypes, mitochondria, metabolism, protein expression, mortalin/client protein complexes, and cell death were evaluated in AN3CA, Hec13b, and Ishikawa endometrial cancer cell lines, and on growth of Ishikawa xenografts. In all three cell lines, SHetA2 inhibited anchorage-independent growth, migration, invasion, and ATP production, and induced G1 cell cycle arrest, mitochondrial damage, and caspase- and apoptosis inducing factor (AIF)-mediated apoptosis. These effects were associated with altered levels of proteins involved in cell cycle regulation, mitochondrial function, protein synthesis, endoplasmic reticulum stress, and metabolism; disruption of mortalin complexes with mitochondrial and metabolism proteins; and inhibition of oxidative phosphorylation and glycolysis. SHetA2 and paclitaxel exhibited synergistic combination indices in all cell lines and exerted greater xenograft tumor growth inhibition than either drug alone. SHetA2 is active against endometrial cancer cell lines in culture and in vivo and acts synergistically with paclitaxel.

A synthetically lethal nanomedicine delivering novel inhibitors of polynucleotide kinase 3'-phosphatase (PNKP) for targeted therapy of PTEN-deficient colorectal cancer

Phosphatase and TENsin homolog deleted on chromosome 10 (PTEN) is a major tumor-suppressor protein that is lost in up to 75% of aggressive colorectal cancers (CRC). The co-depletion of PTEN and a DNA repair protein, polynucleotide kinase 3'-phosphatase (PNKP), has been shown to lead to synthetic lethality in several cancer types including CRC. This finding inspired the development of novel PNKP inhibitors as potential new drugs against PTEN-deficient CRC. Here, we report on the in vitro and in vivo evaluation of a nano-encapsulated potent, but poorly water-soluble lead PNKP inhibitor, A83B4C63, as a new targeted therapeutic for PTEN-deficient CRC. Our data confirmed the binding of A83B4C63, as free or nanoparticle (NP) formulation, to intracellular PNKP using the cellular thermal shift assay (CETSA), in vitro and in vivo. Dose escalating toxicity studies in healthy CD-1 mice, based on measurement of animal weight changes and biochemical blood analysis, revealed the safety of both free and nano-encapsulated A83B4C63, at assessed doses of ≤50 mg/kg. Nano-carriers of A83B4C63 effectively inhibited the growth of HCT116/PTEN^-/- xenografts in NIH-III nude mice following intravenous (IV) administration, but not that of wild-type HCT116/PTEN^+/+ xenografts. This was in contrast to IV administration of A83B4C63 solubilized with the aid of Cremophor EL: Ethanol (CE), which led to similar tumor growth to that of formulation excipients (NP or CE without drug) or 5% dextrose. This observation was attributed to the higher levels of A83B4C63 delivered to tumor tissue by its NP formulation. Our data provide evidence for the success of NPs of A83B4C63, as novel synthetically lethal nano-therapeutics in the treatment of PTEN-deficient CRC. This research also highlights the potential of successful application of nanomedicine in the drug development process.

Enhanced DNA damage response through RAD50 in triple negative breast cancer resistant and cancer stem-like cells contributes to chemoresistance

A growing body of evidence supports the notion that cancer resistance is driven by a small subset of cancer stem cells (CSC), responsible for tumor initiation, growth, and metastasis. Both CSC and chemoresistant cancer cells may share common qualities to activate a series of self-defense mechanisms against chemotherapeutic drugs. Here, we aimed to identify proteins in chemoresistant triple-negative breast cancer (TNBC) cells and corresponding CSC-like spheroid cells that may contribute to their resistance. We have identified several candidate proteins representing the subfamilies of DNA damage response (DDR) system, the ATP-binding cassette, and the 26S proteasome degradation machinery. We have also demonstrated that both cell types exhibit enhanced DDR when compared to corresponding parental counterparts, and identified RAD50 as one of the major contributors in the resistance phenotype. Finally, we have provided evidence that depleting or blocking RAD50 within the Mre11-Rad50-NBS1 (MRN) complex resensitizes CSC and chemoresistant TNBC cells to chemotherapeutic drugs.

Cardiac Protective Effect of Kirenol against Doxorubicin-Induced Cardiac Hypertrophy in H9c2 Cells through Nrf2 Signaling via PI3K/AKT Pathways

Kirenol (KRL) is a biologically active substance extracted from Herba Siegesbeckiae. This natural type of diterpenoid has been widely adopted for its important anti-inflammatory and anti-rheumatic properties. Despite several studies claiming the benefits of KRL, its cardiac effects have not yet been clarified. Cardiotoxicity remains a key concern associated with the long-term administration of doxorubicin (DOX). The generation of reactive oxygen species (ROS) causes oxidative stress, significantly contributing to DOX-induced cardiac damage. The purpose of the current study is to investigate the cardio-protective effects of KRL against apoptosis in H9c2 cells induced by DOX. The analysis of cellular apoptosis was performed using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining assay and measuring the modulation in the expression levels of proteins involved in apoptosis and Nrf2 signaling, the oxidative stress markers. Furthermore, Western blotting was used to determine cell survival. KRL treatment, with Nrf2 upregulation and activation, accompanied by activation of PI3K/AKT, could prevent the administration of DOX to induce cardiac oxidative stress, remodeling, and other effects. Additionally, the diterpenoid enhanced the activation of Bcl2 and Bcl-xL, while suppressing apoptosis marker proteins. As a result, KRL is considered a potential agent against hypertrophy resulting from cardiac deterioration. The study results show that KRL not only activates the IGF-IR-dependent p-PI3K/p-AKT and Nrf2 signaling pathway, but also suppresses caspase-dependent apoptosis.

Parents of ataxia-telangiectasia patients display a distinct cellular immune phenotype mimicking ATM-mutated patients

BACKGROUND

Heterozygous relatives of ataxia-telangiectasia (AT) patients are at an increased risk for certain AT-related manifestations. We also show that there is an increase of infection frequency in parents of AT patients. Thus, we hypothesized that the parents might exhibit immune alterations similar to their affected children.

METHODS

Lymphocyte phenotyping to enumerate T- and B-cell subsets was performed. Functional analyses included in vitro quantified γ-H2AX, poly (ADP-ribose) polymerase (PARP) and caspase-9 proteins. Chromosomal instability was determined by comet assay.

RESULTS

We analyzed 20 AT patients (14F/6M), 31 parents (16F/15M), and 35 age-matched healthy controls. The AT patients' parents exhibited low frequency of naive CD4⁺ T- (n = 14, 45%) and recent thymic emigrants (n = 11, 35%) in comparison with the age-matched healthy donors. Interestingly, parents with low naive T cells also demonstrated high rate of recurrent infections (9/14, 64%). In comparison with age-matched controls, parents who had recurrent infections and low naive T cells showed significantly higher baseline γ-H2AX levels and H₂ O₂ -induced DNA damage as well as increased cleaved caspase-9 and PARP proteins.

CONCLUSION

Parents of AT patients could present with recurrent infections and display cellular defects that mimic AT patients. The observed immunological changes could be associated with increased DNA double-strand breaks.

Development of the phenylpyrazolo[3,4-d]pyrimidine-based, insulin-like growth factor receptor/Src/AXL-targeting small molecule kinase inhibitor

Rationale: The type I insulin-like growth factor receptor (IGF-1R) signaling pathway plays key roles in the development and progression of numerous types of human cancers, and Src and AXL have been found to confer resistance to anti-IGF-1R therapies. Hence, co-targeting Src and AXL may be an effective strategy to overcome resistance to anti-IGF-1R therapies. However, pharmacologic targeting of these three kinases may result in enhanced toxicity. Therefore, the development of novel multitarget anticancer drugs that block IGF-1R, Src, and AXL is urgently needed.

Methods: We synthesized a series of phenylpyrazolo[3,4-d]pyrimidine (PP)-based compounds, wherein the PP module was conjugated with 2,4-bis-arylamino-1,3-pyrimidines (I2) via a copper(I)-catalyzed alkyne-azide cycloaddition reaction. To develop IGF-1R/Src/AXL-targeting small molecule kinase inhibitors, we selected LL6 as an active compound and evaluated its antitumor and antimetastatic effects in vitro and in vivo using the MTT assay, colony formation assays, migration assay, flow cytometric analysis, a tumor xenograft model, the Kras^G12D/+-driven spontaneous lung tumorigenesis model, and a spontaneous metastasis model using Lewis lung carcinoma (LLC) allografts. We also determined the toxicity of LL6 in vitro and in vivo.

Results: LL6 induced apoptosis and suppressed viability and colony-forming capacities of various non-small cell lung cancer (NSCLC) cell lines and their sublines with drug resistance. LL6 also suppressed the migration of NSCLC cells at nontoxic doses. Administration of LL6 in mice significantly suppressed the growth of NSCLC xenograft tumors and metastasis of LLC allograft tumors with outstanding toxicity profiles. Furthermore, the multiplicity, volume, and load of lung tumors in Kras^G12D/+ transgenic mice were substantially reduced by the LL6 treatment.

Conclusions: Our results show the potential of LL6 as a novel IGF-1R/Src/AXL-targeting small molecule kinase inhibitor, providing a new avenue for anticancer therapies.

Discovery of a Secalonic Acid Derivative from Aspergillus aculeatus, an Endophyte of Rosa damascena Mill., Triggers Apoptosis in MDA-MB-231 Triple Negative Breast Cancer Cells

A new secalonic acid derivative, F-7 (1), was isolated from the endophytic Aspergillus aculeatus MBT 102, associated with Rosa damascena. The planar structure of 1 was established on the basis of 1D and 2D NMR and ESI-TOF-MS spectra. The relative configuration of 1 was determined applying a combined quantum mechanical/NMR approach and, afterward, the comparison of calculated and experimental electronic circular dichroism spectra determined the assignment of its absolute configuration. The compound possesses strong cytotoxic activity against triple negative breast cancer (TNBC) cells. It was found to induce apoptosis, as evidenced by scanning electron microscopy and phase contrast microscopy. Furthermore, flow cytometry analyses demonstrated that 1 induced mitochondrial damage and reactive oxygen species mediated apoptosis, arresting the G1 phase of the cells in a dose-dependent manner. Also, the compound causes significant microtubule disruption in TNBC cells. Subsequently, 1 restricted the cell migration leading to the concomitant increase in expression of cleaved caspase and PARP.

Baicalein blocked cervical carcinoma cell proliferation by targeting CCND1 via Wnt/β-catenin signaling pathway

The purpose of this study was to investigate the inhibitory effect of baicalein on the proliferation of cervical carcinoma cells and stimulate cervical carcinoma cells with baicalein. MTT method was used to observe cell proliferation. Flow cytometry was used to observe cell cycle, and gene technology was used to observe the expression of corresponding genes at the level of gene and protein. β-catenin activity was assessed using Western blot and ChIP. Baicalein suppressed cervical carcinoma cell HeLa proliferation by enhancing the activity of caspase-3. Baicalein blocked cell cycle at G0/G1 stage by inhibiting the expression of some genes. At the same time, it can prevent the nuclear translocation of β-catenin and inhibit the activity of Wnt. When the Wnt signaling pathway is increased, the proliferation of HeLa cells is inhibited, and apoptosis is promoted in this way. In conclusion, it indicated that baicalein inhibits cervical carcinoma progression by targeting CCND1 via Wnt/β-catenin signaling pathway.

Endoplasmic reticulum stress induced apoptosis and caspase activation is mediated through mitochondria during megakaryocyte differentiation

Megakaryocytopoiesis involves the process of the development of hematopoietic stem cells into megakaryocytes (MKs), which are the specialized cells responsible for the production of blood platelets. Platelets are one of the crucial factors for hemostasis and thrombosis. In terminally differentiated MKs, many molecular process such as caspase activation and a massive cytoskeletal rearrangement drive the formation of cytoplasmic extensions called proplatelets. These cytoplasmic extensions packed with granules and organelles are then released from the bone marrow into the blood circulation as platelets. Classically, caspase activation is associated with apoptosis and recent reports suggest their involvement in cell differentiation and maturation. There is no clear evidence about the stimulus for caspase activation during megakaryocyte development. In the current study, we attempted to understand the importance of endoplasmic reticulum stress in the caspase activation during megakaryocyte maturation. We used human megakaryoblstic cell line (Dami cells) as an experimental model. We used PMA (Phorbol 12-myristate 13 acetate) to induce megakaryocytic differentiation to understand the involvement of ER stress and caspase activation during MK maturation. Further, we used Thapsigargin, a non-competitive inhibitor of the sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) as a positive control to induce ER stress. We observed larger and adherent cells with the increased expression of megakaryocytic markers (CD41 and CD61) and UPR markers in PMA or Thapsigargin treated cells as compared to control. Also, Thapsigargin treatment induced increased caspase activity and PARP cleavage. The increased expression of megakaryocyte maturation markers alongside with ER stress and caspase activation suggests the importance of ER stress in caspase activation during MK maturation.

Apoptosis induction in lung and prostate cancer cells through silver nanoparticles synthesized from Pinus roxburghii bioactive fraction

The current study was carried out to synthesize silver nanoparticles (AgNPs) via bioactive fraction of Pinus roxburghii needles using a simple, cost-effective, and eco-friendly green chemistry method. As butanol fraction of P. roxburghii exhibited maximum anticancer activity on lung adenocarcinomas (A549) as compared to other fractions therefore, butanol fraction was used to synthesize silver nanoparticles (PNb-AgNPs). The characterization studies by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED) confirmed the synthesis of the nanoparticles. The field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analysis showed the spherical structure of nanoparticles with an average diameter of approximately 80 nm. Interestingly, PNb-AgNPs exhibited significant cytotoxicity towards both A549 and prostatic small cell carcinomas (PC-3) with IC₅₀ values of 11.28 ± 1.28 μg/ml and 56.27 ± 1.17 μg/ml, respectively, while lacking toxicity against normal human breast epithelial cells (fR2) and human peripheral blood lymphocytes (PBL). Further, enhanced reactive oxygen species generation, mitochondrial depolarization, apoptotic cell population (sub-G1) and DNA fragmentation observed in cancer cells were treated with PNb-AgNPs. Apoptosis was demonstrated by caspase-3 and PARP-1 activation in PNb-AgNPs-pretreated cancer cells. These results strongly suggest that PNb-AgNPs are capable of inducing cancer cell death and could act as a therapeutic nanoformulation for cancer.

Replicative senescence of hematopoietic cells in patients with idiopathic cytopenia of undetermined significance

We hypothesized that a subset of idiopathic cytopenia of undetermined significance (ICUS) is associated with an increased autonomous proliferation with exhaustion of hematopoiesis. The aim of this study was to investigate the cell turnover rate and replicative history of the bone marrow cells of ICUS patients. To this end, we examined telomere length (TL), proliferation, and apoptosis of the bone marrow cells of ICUS patients and healthy controls (HCs) using telomere quantitative fluorescence in situ hybridization and immunohistochemical staining for Ki-67 and cleaved caspase-3. We also performed targeted sequencing of 88 myeloid-associated genes. A total of 37 patients with ICUS were enrolled in this study, with a median age of 66 years (range: 31-83). TLs were significantly shorter in patients with ICUS than in the HCs (8.8, interquartile range [IQR] 6.8-12.1 vs 18.4, IQR 14.4-22.0, p < 0.0001). Proliferation (Ki-67-positive) and apoptosis (cleaved caspase-3-positive) were significantly increased in patients with ICUS compared to HCs (median = 20.0% vs 5.0%, p = 0.0003; 45.0% vs 22.5%, p = 0.0005, respectively). The shortening of TL and the increased proliferation and apoptotic activity was also prominent in patients with ICUS without mutation and dysplasia than in HCs (p < 0.0001, p < 0.0001, and p = 0.0093, respectively). TL was not associated with mutational profile and clinical characteristics as well in patients with ICUS. To our knowledge, this is the first study to show that ICUS is associated with premature replicative senescence with increased proliferation and apoptosis of bone marrow cells. Further study is needed to address the cause of replicative exhaustion in ICUS patients.

Autophagy-independent induction of LC3B through oxidative stress reveals its non-canonical role in anoikis of ovarian cancer cells

Cancer cells display abnormal redox metabolism. Autophagy, anoikis and reactive oxygen species (ROS) play a regulatory role during metastasis. LC3 is a well-known essential molecule for autophagy. Therefore, we wanted to explore the molecular interplay between autophagy, anoikis, and ROS in relation to LC3B. We observed enhanced LC3B level along with increased expression of p62 and modulation of other autophagy-related molecules (Atg 3, 5, 7, 12, 16L1 and Beclin1) by inducing oxidative-stress in ovarian cancer cells using a ROS-producing pro-oxidant molecule. Surprisingly, enhanced LC3B was unable to induce autophagosome formation rather promoted anoikis. ROS-induced inhibition of autophagosome-formation is possibly due to the instability of autophagy initiator, ULK1 complex. Moreover, such upregulation of LC3B via ROS enhanced several apoptotic molecules. Silencing LC3B reduced these apoptotic molecules and increased when overexpressed, suggesting its role in apoptosis. Furthermore, LC3B-dependent apoptosis was decreased by inhibiting ROS, indicating a possible link between ROS, LC3B, and apoptosis. Additionally, ROS-induced enhanced LC3B promoted detachment-induced cell death (anoikis). This was further reflected by reduced cell adhesion molecules (integrin-β3 and focal adhesion kinase) and mesenchymal markers (snail and slug). Our in vitro experimental data was further confirmed in primary tumors developed in syngeneic mice, which also showed ROS-mediated LC3B enhancement along with reduced autophagosomes, integrin-β3 and focal adhesion kinase ultimately leading to the decreased tumor mass. Additionally, primary cells from high-grade serous carcinoma patient's ascites exhibited LC3B enhancement and autophagy inhibition through ROS which provided a clinical relevance of our study. Taken together, this is the first evidence for a non-canonical role of LC3B in promoting anoikis in contrast to autophagy and may, therefore, consider as a potential therapeutic target molecule in ovarian cancer. Taken together, autophagy-inhibition may be an alternative approach to induce apoptosis/anoikis in cancer.

Baicalein induces cervical cancer apoptosis through the NF-κB signaling pathway

To investigate the mechanism of baicalein in inducing human cervical cancer cell line C33A apoptosis. Baicalein (200 µM) was used to treat C33A cells. Cell proliferation was tested by the MTT assay. Cell apoptosis was detected by the TUNEL assay and caspase‑3 activity measurement. Cell cycle was determined by flow cytometry and associated gene expression at mRNA and protein levels. Nuclear factor (NF)‑κB activity was assessed by luciferase assay and western blotting. Baicalein suppressed cervical cancer cell C33A proliferation and induced cell apoptosis by activating caspase‑3 activity. Baicalein blocked cell cycle in G0/G1 phase through regulating the expression of associated genes. Baicalein inhibited NF‑κB activity by repressing nuclear translocation. Baicalein suppressed C33A proliferation and promoted cellular apoptosis by inhibiting NF‑κB signaling pathway. In conclusion, the results indicate that baicalein can inhibit cervical cancer cell proliferation and promote cell apoptosis by affecting NF-κB activity.

Targeting cancer cells through antibiotics-induced mitochondrial dysfunction requires autophagy inhibition

A significant part of current research studies utilizes various cellular models which imply specific antibiotics-containing media as well as antibiotics used for clonal selection or promoter de/activation. With the great success of developing such tools, mitochondria, once originated from bacteria, can be effectively targeted by antibiotics. For that reason, some studies propose antibiotics-targeting of mitochondria as part of anticancer therapy. Here, we have focused on the effects of various classes of antibiotics on mitochondria in cancer and non-cancer cells and demonlow mitochondrial membrane potential, reduced ATP production, altered morphology and lowered respiration rate which altogether suggested mitochondrial dysfunction (MDF). This was in parallel with increased level of reactive oxygen species (ROS) and decreased activity of mitochondrial respiration complexes. However, both survival and repopulation capacity of cancer cells was not significantly affected by the antibiotics, perhaps due to a glycolytic shift or activated autophagy. In turn, simultaneous inhibition of autophagy and treatment with antibiotics largely reduced tumorigenic properties of cancer cells suggesting potential strategy for anticancer therapy.

Impaired mitophagy in Fanconi anemia is dependent on mitochondrial fission

Fanconi anemia (FA) is a rare genetic disorder associated with bone-marrow failure, genome instability and cancer predisposition. Recently, we and others have demonstrated dysfunctional mitochondria with morphological alterations in FA cells accompanied by high reactive oxygen species (ROS) levels. Mitochondrial morphology is regulated by continuous fusion and fission events and the misbalance between these two is often accompanied by autophagy. Here, we provide evidence of impaired autophagy in FA. We demonstrate that FA cells have increased number of autophagic (presumably mitophagic) events and accumulate dysfunctional mitochondria due to an impaired ability to degrade them. Moreover, mitochondrial fission accompanied by oxidative stress (OS) is a prerequisite condition for mitophagy in FA and blocking this pathway may release autophagic machinery to clear dysfunctional mitochondria.

ROMO1 regulates RedOx states and serves as an inducer of NF-κB-driven EMT factors in Fanconi anemia

Fanconi anemia (FA) is a rare genetic disorder associated with a bone-marrow failure, genome instability, hypersensitivity to DNA crosslinking agents and a predisposition to cancer. Mutations have been documented in 16 FA genes that participate in the FA-BRCA DNA repair pathway, a fundamental pathway in the development of the disease and the presentation of its symptoms. Besides the well-established role of FA genes in DNA damage and repair pathways, recent reports have revealed an overproduction of epithelial to mesenchymal transition (EMT) factors via a NF-κB-dependent mechanism that results in the proliferation of neighboring tumor cells and FA cells have also been shown to possess damaged mitochondria, accompanied by altered RedOx pathways. This study has focused on reactive oxygen species Modulator-1 (ROMO1), an oncomarker and mitochondrial membrane protein, which is known to be associated with cancer growth and in the modulation of RedOx states in some cancer models. Here, we reveal the role of ROMO1 and demonstrate its link in regulating RedOx states and in the activation of NF-κB-dependent EMT factors in FA.

IL-6, IL-8, MMP-2, MMP-9 are overexpressed in Fanconi anemia cells through a NF-κB/TNF-α dependent mechanism

Fanconi anemia (FA) is a rare autosomal recessive genetic disorder associated with a bone-marrow failure, genome instability, hypersensitivity to DNA crosslinking agents and a predisposition to cancer. Mutations have been documented in 16 FA genes that participate in the FA-BRCA DNA repair pathway, a fundamental pathway in the development of the disease and the presentation of its symptoms. FA cells have been characterized by an overproduction of cytokines, MAPKs, and Interleukins. Through this study we have identified the overexpression of additional secretory factors such as IL-6, IL-8, MMP-2, and MMP-9 in FA cells and in cells depleted of FANCA or FANCC and proved that their expression is under the control of NF-κB/TNF-α signaling pathways. We also demonstrated that these overexpressed secretory factors were effective in promoting the proliferation, migration, and invasion of surrounding tumor cells a fundamental event in the process of epithelial mesenchymal transition (EMT) and that they also modulated the expression of EMT markers such as E-cadherin and SNAIL. Overall our data suggest that the upregulation of EMT promoting factors in FA may contribute to predisposing FA patients to cancer, thereby providing new insights into possible therapeutic interventions.

Damaged mitochondria in Fanconi anemia - an isolated event or a general phenomenon?

Fanconi anemia (FA) is known as an inherited bone marrow failure syndrome associated with cancer predisposition and susceptibility to a number of DNA damaging stimuli, along with a number of clinical features such as upper limb malformations, increased diabetes incidence and typical anomalies in skin pigmentation. The proteins encoded by FA-defective genes (FANC proteins) display well-established roles in DNA damage and repair pathways. Moreover, some independent studies have revealed that mitochondrial dysfunction (MDF) is also involved in FA phenotype. Unconfined to FA, we have shown that other syndromes featuring DNA damage and repair (such as ataxia-telangiectasia, AT, and Werner syndrome, WS) display MDF-related phenotypes, along with oxidative stress (OS) that, altogether, may play major roles in these diseases. Experimental and clinical studies are warranted in the prospect of future therapies to be focused on compounds scavenging reactive oxygen species (ROS) as well as protecting mitochondrial functions.

Cleavage of poly (ADP-ribose) polymerase-1 is involved in the process of porcine ovarian follicular atresia

Ovarian follicle atresia is a common phenomenon in vertebrate ovaries and this process is characterized by follicular wall degeneration. The molecular mechanism underlying follicle atresia is apoptotic granulusa cell death; however, the exact signaling pathway is still unclear. PARP-1, the founding member of the poly (ADP-ribose) polymerase (PARP) family, plays an important role in a large variety of physiological processes. Although its cleavage has recently been implicated in a variety of physiological and pathological processes, its role in the process of follicular atresia is not yet completely defined. We identified the cleavage of PARP-1 involved in the process of follicle degeneration, which is known as "follicular atresia", both from in vivo models and cell culture data. The results from immunohistochemistry (IHC) showed that cleaved PARP-1 was mainly located in apoptotic granulosa cells (GCs); and the expression of PARP-1 and caspase-3 were decreased in apoptotic granulosa cells (GCs). The results from western blotting showed that PARP-1 expression was significantly decreased in atretic follicles compared with healthy (H) follicles, and the cleavage of caspase-3 (17kDa) significantly increased in atretic follicles. Along with the cleavage of caspase-3, the expression of cleaved PARP-1 (24kDa) product was significantly increased, which confirmed caspase-3 activation. Serum starvation led to a reduction in PARP-1 and an increase in cleaved PARP-1 (24kDa) and caspase-3 (17kDa), suggesting that caspase-3 was activated under the stress of withdrawal of growth factors, in accordance with the in vivo study. In the present study, the concentrations of estradiol (E2) and progesterone (P4) as well as the P4/E2 (P/E) ratio were combined with morphological features to determine follicular classification. In summary, the present study demonstrated that cleavage of PARP-1 by caspase-3 was involved in the process of granulosa cell apoptosis. PARP-1 may through its cleavage act as a critical regulator in the process of porcine follicular atresia. Our results identified that cleavage of PARP-1 by activated (cleaved) caspase-3 may serve a key role in controlling follicular atresia through granulosa cell degeneration. These findings should prove helpful in understanding the regulatory mechanisms controlling follicular development and atresia.

Damaged mitochondria and overproduction of ROS in Fanconi anemia cells

Fanconi anemia (FA) is a heterogeneous disease associated with a bone marrow failure, cancer predisposition and hypersensitivity to DNA crosslinking agents. To date, 15 different genes have been shown to cause FA, all of which have some role in repair of defective DNA interstrand crosslinks. On a biochemical level, many FA individuals display insufficient growth hormone production, abnormal glucose or insulin metabolism. Clinical phenotype may include hydrocephalia, the erythrophagocytosis and diabetes mellitus, thus linking FA with metabolic disorders that involve impaired oxygen metabolism and mitochondrial alterations. Our recent study demonstrates the decrease of FA mitochondrial membrane potential, low ATP production, impaired oxygen uptake and pathological changes in the morphology of FA mitochondria. This is accompanied by inactivation of the enzymes responsible for energy production and detoxification of ROS. We also propose that FA oversensitivity to DNA crosslinkers may be caused by the overproduction of mitochondrial ROS.

Evidence of mitochondrial dysfunction and impaired ROS detoxifying machinery in Fanconi anemia cells

Fanconi Anemia (FA) is a rare genetic disorder associated with a bone-marrow failure, cancer predisposition and hypersensitivity to DNA crosslinking agents. Majority of the 15 FA genes and encoded proteins characterized so far are integrated into DNA repair pathways, however, other important functions cannot be excluded. FA cells are sensitive to oxidants, and accumulation of oxidized proteins has been characterized for several FA subgroups. Clinical phenotypes of both FA and other closely related diseases suggest altered functions of mitochondria, organelles responsible for cellular energetic metabolism, and also serving as an important producer and the most susceptible target from reactive oxidative species (ROS). In this study, we have shown that elevated level of mitochondrial ROS in FA cells is in parallel with the decrease of mitochondrial membrane potential, the decrease of ATP production, impaired oxygen uptake and pathological changes in the morphology of mitochondria. This is accompanied by inactivation of enzymes that are essential for the energy production (F1F0ATPase and cytochrome C oxidase) and detoxification of ROS (superoxide dismutase, SOD1). In turn, overexpression of SOD1 could rescue oxygen consumption rate in FA-deficient cells. Importantly, the depletion of mitochondria improved survival rate of mitomycin C treated FA cells suggesting that hypersensitivity of FA cells to chemotherapeutic drugs could be in part due to the mitochondria-mediated oxidative stress. On the basis of our results, we propose that deficiency in FA genes lead to disabling mitochondrial ROS-scavenging machinery further affecting mitochondrial functions and suppressing cell respiration.

BIK (NBK) is a mediator of the sensitivity of Fanconi anaemia group C lymphoblastoid cell lines to interstrand DNA cross-linking agents

FA (Fanconi anaemia) is a rare hereditary disorder characterized by congenital malformations, progressive bone marrow failure and an extraordinary predisposition to develop cancer. At present, 15 genes have been related to this condition and mutations of them have also been found in different types of cancer. Bone marrow failure threatens the life of FA patients during the first decade of their life, but the mechanisms underlying this process are not completely understood. In the present study we investigate a possible imbalance between the expression of pro- and anti-apoptotic proteins as a cause for the hypersensitivity of FANCC (FA, complementation group C)-deficient cells to genotoxic stress. We found a BIK (Bcl-2 interacting killer) over-expression in lymphoblastoid cell lines derived from FA-C patients when compared with their phenotypically corrected counterparts. This overexpression has a transcriptional basis since the regulatory region of the gene shows higher activity in FANCC-deficient cells. We demonstrate the involvement of BIK in the sensitivity of FA-C lymphoblasts to interstrand DNA cross-linking agents as it is induced by these drugs and interference of its expression in these cells preserves their viability and reduces apoptosis. We investigate the mechanism of BIK overexpression in FANCC-deficient cells by analysing the activity of many different signalling pathways in these cells. Finally, we provide evidence of a previously undescribed indirect epigenetic regulation of BIK in FA-C lymphoblasts mediated by ΔNp73, an isoform of p73 lacking its transactivation domain that activates BIK through a proximal element in its promoter.

Increased apoptosis is linked to severe acute GVHD in patients with Fanconi anemia

Fanconi anemia (FA) patients have an increased risk of acute GVHD (aGVHD) after hematopoietic SCT, with hypersensitivity to DNA-cross-linking agents and defective DNA repair. MicroRNA-34 and p53 can induce apoptosis after DNA damage.Here we assessed epithelial cell apoptosis, and studied TP53 and miR-34a expression in the skin and gut biopsies in five non-transplanted FA patients, in 20 FA patients with aGVHD and in 25 acquired aplastic anemia patients (AA). Epithelial apoptosis was higher in FA than in acquired AA patients in both the skin and gut biopsies, though they had a similar preparative regimen. Further study on gut biopsies in FA patients showed that this deleterious effect was not linked to TP53 gene overexpression. As, among p53-independent signaling pathways of apoptosis, the microRNA-34 family mimics p53 apoptotic effects in response to DNA damage, we studied miR-34a expression in the same series of FA patients' gut biopsies. MiR-34a expression level was higher in severe aGVHD compared with non-aGVHD subjects or non-transplanted patients, and significantly related to apoptotic cell numbers across the three groups of FA patients. Thus, in FA patients, increased apoptosis occurs in target epithelial cells of severe aGVHD, and this deleterious effect is linked to overexpression of miR-34a but not TP53.

Enhancement of synthetic lethality via combinations of ABT-888, a PARP inhibitor, and carboplatin in vitro and in vivo using BRCA1 and BRCA2 isogenic models

Individuals with an inherited BRCA1 or BRCA2 mutation have an elevated risk of developing breast cancer. The resulting tumors typically lack homologous recombination repair as do a subset of sporadic tumors with acquired BRCA deficiency. Clinical responses to monotherapy with platinum drugs or poly PARP inhibitors (PARPi) have been shown for BRCA-associated cancers. However, there are limited data on combination therapy with PARPi and platinum drugs, the mechanism of action of this combination, and the role of BRCA1 or BRCA2 in chemosensitivity. We compared the efficacy of ABT-888 (a PARPi) with that of cisplatin or carboplatin (platinum drugs) alone or in combinations by examining the survival of treated Brca-proficient and -deficient mouse embryonic stem cells. In addition, drug-induced growth inhibition of a BRCA1 and a BRCA2 null cell line were compared with their isogenic BRCA-complemented lines. Although each monotherapy killed or inhibited proliferation of Brca/BRCA-deficient cells, an enhanced effect was observed after treatment with ABT-888 in combination with carboplatin. Moreover, the ABT-888/carboplatin combination delayed tumor growth in Brca2 xenografts. The drugs caused DNA damage and apoptosis. Along with greater PARP activity in Brca/BRCA-deficient cells, these effects correlated with increased chemosensitivity. Our data suggest that ABT-888 and carboplatin combination treatment will be more successful than monotherapy in addressing many BRCA-associated cancers. A randomized phase II trial has recently been initiated to test this hypothesis to assist in the discovery of more effective therapies for patients with BRCA.

Fanconi anemia protein FANCD2 inhibits TRF1 polyADP-ribosylation through tankyrase1-dependent manner

Background

Fanconi anemia (FA) is a rare autosomal recessive syndrome characterized by developmental abnormalities, progressive bone marrow failure, and predisposition to cancer. The key FA protein FANCD2 crosstalks with members of DNA damage and repair pathways that also play a role at telomeres. Therefore, we investigated whether FANCD2 has a similar involvement at telomeres.

Results

We reveal that FANCD2 may perform a novel function separate to the FANCD2/BRCA pathway. This function includes FANCD2 interaction with one of the telomere components, the PARP family member tankyrase-1. Moreover, FANCD2 inhibits tankyrase-1 activity in vitro. In turn, FANCD2 deficiency increases the polyADP-ribosylation of telomere binding factor TRF1.

Conclusions

FANCD2 binding and inhibiting tankyrase-1PARsylation at telomeres may provide an additional step within the FA pathway for the regulation of genomic integrity.