Treatment of MCF-7 cells with taxol and etoposide induces distinct alterations in the expression of apoptosis-related genes BCL2, BCL2L12, BAX, CASPASE-9 and FAS

Anticancer potential of Marina Crystal Minerals (MCM) against the growth of murine mammary adenocarcinoma cells in vivo

In vitro studies have shown that Marina Crystal Minerals (MCM), a crystallized mixture of minerals and trace elements from sea water, possesses apoptotic and immune modulatory effects in human breast cancer cells MDA-MB-231. The current study aimed to evaluate MCM's anticancer effect in vivo against murine mammary adenocarcinoma cells and to explore its underlying mechanisms. Mice were inoculated intramuscularly with Ehrlich ascites carcinoma (EAC) cells, a breast adenocarcinoma. Tumors became palpable within 9 days. Tumor-bearing mice were injected with MCM intraperitoneally (IP) or intratumorally (IT) at a dose of 40 mg/kg BW for 6 days/week until day 28 post-inoculation. Tumor growth, cell cycle progression, cell cycle regulatory proteins, apoptosis, apoptotic regulatory markers, mitochondrial membrane potential (MMP), natural killer (NK) cell activity, and histopathological effects were investigated. Treatment with MCM reduced tumor volume by 49.4% for IP and 59.5% for IT injection. MCM induced cancer cell apoptosis, as indicated by a sub-G1 peak and confirmed by Annexin V/PI assay and histopathological examination. This was mediated by increased Bax expression, caspase-3 activation, decreased Bcl-2 expression, and MMP disruption. Furthermore, MCM treatment induced G1 cell cycle arrest, mediated through significantly increased expression of p53, p21, and p27 and decreased expression of cyclin D1 and PCNA in cancer cells. Finally, MCM treatment markedly enhanced NK cell cytotoxicity. MCM possesses chemopreventive potential to reduce tumor growth by suppressing cell proliferation, inducing apoptosis in EAC cells via a mitochondrial dependent pathway, and activating the immune system. Our results suggest MCM's beneficial potential for treating breast adenocarcinoma.

Nanoflare Couple: Multiplexed mRNA Imaging and Logic-Controlled Combinational Therapy

Theranostics, which combines both diagnostic and therapeutic capabilities in one dose, has always been an intractable challenge in personalized cancer treatment. Herein, a versatile nanotheranostic platform "nanoflare couple (NC)" has been developed for in situ multiplex cancer-related mRNA imaging and subsequent logic-controlled aggregation of gold nanoparticles, leading to gene therapy and photothermal therapy upon irradiation with infrared light. As a proof of concept, TK1 and survivin mRNAs that are highly expressed in most tumor tissues are selected as endogenous cancer indicators and therapy triggers to design the NC. Mice bearing breast cancer cells MCF-7 are prepared as a model to test its efficacy. The in vitro and in vivo assays validate that the NC show the capability for multiplexed mRNA imaging and high efficiency for logic-controlled combinational therapy of breast cancer.

Whole Grain Consumption for the Prevention and Treatment of Breast Cancer

Breast cancer is one of the most common and malignant cancers among females worldwide. Several epidemiological studies have indicated the inverse correlation between the intake of whole grains and the incidence of breast cancer. Whole grains are the most fundamental and important food source of bioactive phytochemicals, which have well-defined roles in the management of each stage of breast carcinogenesis. To better understand the value of whole grains in future prevention and treatment of breast cancer, the effects and possible mechanisms of six different whole grain cereals, which are the most commonly consumed throughout the world, are introduced in the current review. Moreover, the bioactive compounds extracted from whole grains are adequately formulated and the underlying mechanism of action is illustrated. In addition, the present limitations and future perspective of whole grain consumption for breast cancer are also concluded. The objective of this review is to promote the development of nutraceutical and functional food from whole grains and its application for reducing the risk of breast cancer.

Cambogin exerts anti-proliferative and pro-apoptotic effects on breast adenocarcinoma through the induction of NADPH oxidase 1 and the alteration of mitochondrial morphology and dynamics

Cambogin, a bioactive polycyclic polyprenylated acylphoroglucinol (PPAP) derived from the Garcinia genus, possesses proapoptotic effect in medulloblastoma and breast cancer cells. We have previously demonstrated that the proapoptotic effect of cambogin is driven by the production of reactive oxygen species (ROS). Here we have shown that the inhibitory effect of cambogin on cell proliferation is associated with the loss of mitochondrial transmembrane potential (ΔΨ_m) and mitochondrial fragmentation. Cambogin also promotes the mutual complex formation of the membrane-bound subunit p22^phox of NADPH oxidase 1 (NOX1), as well as the phosphorylation of the cytosolic subunit p47^phox, subsequently enhancing membrane-bound NOX1 activity, which leads to increases in intracellular and mitochondrial levels of O₂^.- and H₂O₂. Pharmacological inhibition of NOX1 using apocynin (pan-NOX inhibitor), ML171 (NOX1 inhibitor) or siRNA against NOX1 prevents the increases in O₂^.- and H₂O₂ levels and the anti-proliferative effect of cambogin. Antioxidants, including SOD (superoxide dismutase), CAT (catalase) and EUK-8, are also able to restore cell viability in the presence of cambogin. Besides, cambogin increases the dissociation of thioredoxin-1 (Trx1) from ASK1, switching the inactive form of ASK1 to the active kinase, subsequently leads to the phosphorylation of JNK/SAPK, which is abolished upon ML171 treatment. The proapoptotic effect of cambogin in breast cancer cells is also aggravated upon knocking down Trx1 in MCF-7 cells. Taken in conjunction, these data indicate that the anti-proliferative and pro-apoptotic effect of cambogin is mediated via inducing NOX1-dependent ROS production and the dissociation of ASK1 and Trx1.

Differential roles of Bcl2L12 and its short variant in breast cancer lymph node metastasis

Bcl2L12 plays a role in post-mitochondrial apoptosis through multiple mechanisms involving p53, αB-crystallin, caspase-3 and -7 in glioblastoma. Bcl2L12 is reported to be a good prognostic marker in breast cancer and correlated with ER and Bcl2 expression status. However, the mechanisms by which Bcl2L12 regulates apoptosis in breast cancer (BCa) remain unknown. Recent studies have shown that Bcl2L12 expression is a useful biomarker in other types of cancer. Thus, we examined whether Bcl2L12 and Bcl2L12A mRNA were associated with breast cancer progression or a specific subtype. In total, 106 paraffin-embedded, different stage breast cancer specimens were prepared and quantified for Bcl2L12 and Bcl2L12A expression by PCR. The correlation between Bcl2L12 and Bcl2L12A mRNA levels and clinicopathological characteristics was statistically analyzed. The results showed that Bcl2L12 and Bcl2L12A mRNA expression was not significantly different across the different stage, grade and TNM classification groups (P>0.005). Using linear regression, Bcl2L12 mRNA was associated with Bcl2L12A mRNA, grade 3 tumor and the triple-negative breast cancer (TNBC) subtype. In non-TNBC specimens, Bcl2L12 mRNA was only correlated with Bcl2L12A mRNA. Bcl2L12A mRNA was positively associated with Bcl2L12 mRNA and the number of lymph node metastases, but negatively correlated with staging in the non-TNBC group. Specifically, Bcl2L12, but not Bcl2L12A, mRNA was significantly higher in TNBC and grade 3 tumors, respectively. In non-TNBC, Bcl2L12A mRNA was significantly highly expressed in tumors with ≥ 12 metastatic lymph nodes. Bcl2L12 and its variant mRNA were highly expressed in carcinoma in situ (CIS) samples. In addition, they were estimated to be correlated with the total sample and non-TNBC, but not the TNBC group. In summary, a high Bcl2L12 mRNA expression was associated with the high-grade BCa and TNBC subtype. In addition, the interplay between Bcl2L12 and its variant may be associated with high lymph node metastasis in non-TNBC tumors.

A let-7b binding site SNP in the 3'-UTR of the Bcl-xL gene enhances resistance to 5-fluorouracil and doxorubicin in breast cancer cells

The development of acquired resistance to chemotherapy is a major obstacle in the successful treatment of cancer. In breast cancer cells, B-cell lymphoma-extra large (Bcl-xL) is involved in the development of resistance to various chemotherapeutic agents; therefore, preliminary biological prediction was performed to identify a putative binding site for let-7b in the 3'-untranslated region (UTR) of the Bcl-xL gene and a single nucleotide polymorphism (SNP) within this binding region. The present study investigated the association between the SNP rs3208684 A>C and chemotherapeutic agent resistance in breast cancer cells. The data indicated that let-7b negatively regulates the expression of Bcl-xL and appears to sensitize MCF-7 cells to the chemotherapeutic agents 5-fluorouracil (5-FU) and doxorubicin. Furthermore, the SNP rs3208684 A>C was demonstrated to enhance Bcl-xL protein expression by disrupting the binding of let-7b to the 3'-UTR of Bcl-xL and, in MCF-7 cells, overexpression of let-7b in the presence of a mutant Bcl-xL 3'-UTR (C allele) significantly increased 5-FU and doxorubicin resistance. Thus, the results of the present study demonstrate that the SNP rs3208684 A>C may upregulate Bcl-xL protein expression and enhance the resistance of the MCF-7 cells to 5-FU and doxorubicin by decreasing the binding of let-7b to the 3'-UTR of Bcl-xL.

Molecular cloning of novel alternatively spliced variants of BCL2L12, a new member of the BCL2 gene family, and their expression analysis in cancer cells

In the past, we identified and cloned the BCL2-like 12 (BCL2L12) gene, a novel member of the BCL2 family, which is implicated in various malignancies. The classical BCL2L12 protein isoform contains a highly conserved BH2 domain, a BH3-like motif, and a proline-rich region, and is involved in apoptosis. Most members of this apoptosis-related family are subjected to alternative splicing, thus generating multiple protein isoforms with distinct properties, and sometimes even with opposite function (pro- vs. anti-apoptotic). In the current study, we report the identification, molecular cloning, and expression pattern of novel splice variants of the human BCL2L12 gene in cancer cell lines. EST clones displaying high sequence identity (≥90%) with the classical BCL2L12 transcript were aligned, in order to identify those containing at least one novel splice junction. EST database mining led to the identification of three previously unknown splice variants of this apoptotic gene. In our effort to experimentally validate these novel transcripts, we also cloned seven more, previously unidentified, BCL2L12 alternatively spliced variants. Expression analysis of all BCL2L12 splice variants in human cancer cell lines and embryonic kidney cells revealed remarkable differences between their BCL2L12 expression profiles. Interestingly, 7 out of 10 novel splice variants of BCL2L12 are predicted to encode new protein isoforms, some of which are BH3-only proteins, in contrast to the classical BCL2L12 isoform, which also contains a functional BH2 domain. The remaining three novel splice variants of BCL2L12 are nonsense-mediated mRNA decay (NMD) candidates.

Paclitaxel-loaded polyester nanoparticles prepared by spray-drying technology: in vitro bioactivity evaluation

Paclitaxel (PTX), an antimicrotubular agent used in the treatment of ovarian and breast cancer, was encapsulated in nanoparticles (NPs) of poly(lactide-co-glycolide) (PLGA) and poly(ε-caprolactone) (PCL) polymers using the spray-drying technique. Morphology, size distribution, drug encapsulation efficiency, thermal degradation and drug release were characterized. MCF7 cells were employed to evaluate the efficacy of the systems on cell cycle and cytotoxicity. The particle size was in the range 0.8-1 µm. The incorporation efficiency of PTX was more than 80% in all NPs obtained. In vitro drug release took place during 35 days, and drug release rates were in the order PCL > PLGA 50:50 > PLGA 75:25. Unloaded NPs showed to be cytocompatible at MCF7 cells. PTX-loaded NPs demonstrated the release of the drug block cells in the G2/M phase. All PTX-loaded formulations showed their efficacy in killing MCF7 cells, mainly PTX-loaded PLGA 50:50 and PLGA 75:25 that cause a decrease in cell viability lower than 20%.

The Role of BCL2 Family of Apoptosis Regulator Proteins in Acute and Chronic Leukemias

The disturbance of apoptosis molecular signaling pathways is involved in carcinogenesis. BCL2 family of proteins is the hallmark of apoptosis regulation. In the last decade, new members of BCL2 gene family were discovered and cloned and were found to be differentially expressed in many types of cancer. BCL2 protein family, through its role in regulation of apoptotic pathways, is possibly related to cancer pathophysiology and resistance to conventional chemotherapy. It is well known that leukemias are haematopoietic malignancies characterized by biological diversity, varied cytogenetics, different immunophenotype profiles, and diverse outcome. Current research focuses on the prognostic impact and specific role of these proteins in the pathogenesis of leukemias. The understanding of the molecular pathways that participate in the biology of leukemias may lead to the design of new therapies which may improve patients' survival. In the present paper, we describe current knowledge on the role of BCL2 apoptosis regulator proteins in acute and chronic leukemias.

BCL2L12 is a novel biomarker for the prediction of short-term relapse in nasopharyngeal carcinoma

BCL2-like 12 (BCL2L12 ) is a new member of the apoptosis-related BCL2 gene family, members of which are implicated in various malignancies. Nasopharyngeal carcinoma is a highly metastatic, malignant epithelial tumor, with a high prevalence in Southeast Asia and North Africa. The purpose of the current study was to quantify and investigate the expression levels of the BCL2L12 gene in nasopharyngeal carcinoma biopsies and to assess its prognostic value. Total RNA was isolated from 89 malignant and hyperplastic nasopharyngeal biopsies from Tunisian patients. After testing the quality of the extracted RNA, cDNA was prepared by reverse transcription. A highly sensitive real-time polymerase chain reaction (PCR) method for BCL2L12 mRNA quantification was developed using SYBR Green chemistry. GAPDH served as a reference gene. Relative quantification analysis was performed using the comparative C(T) (2(-ΔΔCT)) method. Higher BCL2L12 mRNA levels were detected in undifferentiated carcinomas of the nasopharynx, rather than in nonkeratinizing nasopharyngeal tumors (P = 0.045). BCL2L12 expression status was also found to be positively associated with the presence of distant metastases (P = 0.014). Kaplan-Meier survival analysis demonstrated that patients with BCL2L12-positive nasopharyngeal tumors have significantly shorter disease-free survival (P = 0.020). Cox regression analysis showed BCL2L12 expression to be an unfavorable and independent prognostic indicator of short-term relapse in nasopharyngeal carcinoma (P = 0.042). Our results suggest that mRNA expression of BCL2L12 may constitute a novel biomarker for the prediction of short-term relapse in nasopharyngeal carcinoma.

BCL2L12A localizes to the cell nucleus and induces growth inhibition through G2/M arrest in CHO cells

BCL2L12, a newly identified member of Bcl-2 family, and its transcript variant BCL2L12A have been found to be associated with favorable prognosis in breast cancer patients while correlated with tumorigenesis of glioblastoma and colon cancer. However, the biological functions of BCL2L12 and especially those of BCL2L12A are largely unknown. Here, we report that, unlike other Bcl-2 family proteins, BCL2L12 and its transcript variant BCL2L12A are nuclear proteins. Interestingly, BCL2L12 forms speckle patterns in the nuclei and potently induces apoptosis in CHO cells. BCL2L12A had a diffuse distribution in the nuclei and inhibits cell growth by inducing cell cycle arrested at G2/M transition in CHO cells. More importantly, BCL2L12A-induced G2/M arrest was associated with a slight up-regulation of cyclin B1 and significant down-regulation of an active form of cyclin B1 phosphorylated at Ser147. Taken together, our study suggests that both BCL2L12 and BCL2L12A have negative effects on CHO cell growths, and that BCL2L12A is a potential cell cycle regulator that interferes with G2-M transition.

Alteration in TWIST expression: possible role in paclitaxel-induced apoptosis in human laryngeal carcinoma Hep-2 cell line

AIM

To explore the relationship between alteration in the expression of TWIST, highly conserved transcription factor from the basic helix-loop-helix family, and apoptosis of Hep-2 cells induced by chemotherapeutic agent paclitaxel.

METHODS

Morphological changes of Hep-2 cells were observed by acridine orange cytochemistry staining. Viability of Hep-2 cells treated with various concentrations of paclitaxel was examined by cell proliferation assay. Apoptosis was examined by flow cytometry. The mRNA and protein expression of TWIST in response to paclitaxel at 24 hours, 48 hours, and 72 hours was examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively.

RESULTS

Typical morphological changes of apoptotic cells at 24 hours, 48 hours, or 72 hours after treatment wiyth paclitaxel (10x10(-9) mol/L) were observed. The cell survival rates significantly decreased in a concentration- and time-dependent manner (P=0.001). Paclitaxel-induced apoptosis increased with culture time (22.6+/-5.3% after 24 hours, 38.7+/-7.9% after 48 hours, and 52.4+/-14.3% after 72 hours; P=0.002). Both mRNA and protein expression of TWIST was markedly decreased at both mRNA levels and protein levels, at 24 hours, 48 hours, and 72 hours in the paclitaxel-induced apoptosis of Hep-2 cells (P<0.001).

CONCLUSION

TWIST, which has a significantly decreased expression in response to paclitaxel in Hep-2 cells, may play a pivotal role in paclitaxel-induced apoptosis of Hep-2 cells.

Molecular analysis and prognostic impact of the novel apoptotic gene BCL2L12 in gastric cancer

Stomach cancer comprises a malignancy with feeble prognosis. In gastric carcinogenesis, molecular alterations in the apoptosis-related genes have been described. In this study, the expression of BCL2-like-12 (BCL2L12) gene, discovered and cloned by members of our group, was investigated in a statistically significant sample size of cancerous and non-cancerous stomach tissues and gastric cancer cells with quantitative real-time PCR methodology. BCL2L12 transcript was indicated in cancer gastric tissues to range from 29 to 53200 mRNA copies BCL2L12/10(6) mRNA copies GAPDH. Significant associations of BCL2L12 with gastric tumors of the early stages (I/II) (p=0.044) and of intestinal histotype (p=0.034) was substantiated. Both univariate and multivariate analyses disclosed, respectively, BCL2L12 relationship with disease-free (p=0.006 and p=0.025) and overall patients' survival (p=0.007 and p=0.022). Our results open new horizons for the possible application of BCL2L12 as a novel prognostic indicator of gastric cancer.

Molecular response of HL-60 cells to mitotic inhibitors vincristine and taxol visualized with apoptosis-related gene expressions, including the new member BCL2L12

Taxol and vincristine belong to a group of anticancer drugs that target microtubules, subsequently arresting cells at the mitotic phase of the cell cycle and inducing programmed cell death. The BCL2 (bcl-2) family of genes is of known implication in apoptosis induced by various stimuli, among which BCL2L12, a new member of the family, cloned by our group. For further insights into the mechanisms and molecular targets implicated and modified as a result of apoptosis induced by these two mitosis-arresting drugs, we studied the possible alterations, at the mRNA level, of various apoptosis-related genes (BCL2, BAX, BCL2L12, CASPASE-3, FAS) after leukemia cell (HL-60) treatment with these drugs. The kinetics of cell toxicity were evaluated by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method, trypan blue staining, and cell proliferation efficiency; apoptosis induction was assayed by endonucleosomal cleavage of DNA (DNA laddering); and the expression levels of the genes were analysed by RT-PCR, using gene-specific primers. The percentage of nonviable cells was upregulated with increasing cell exposure time and drug concentrations to both taxol and vincristine. Distinct modulations of apoptosis-related genes at the mRNA level were also observed, mainly concerning BCL2 and BCL2L12 along apoptosis induction. Our results indicate and support the hypothesis that the apoptosis-related genes BCL2 and BCL2L12 respond similarly to treatment of the human, acute, myelocytic leukemia HL60 cells with the anticancer drugs vincristine and taxol though in a drug-specific and time-dependent manner.

Molecular profile of breast versus ovarian cancer cells in response to treatment with the anticancer drugs cisplatin, carboplatin, doxorubicin, etoposide and taxol

We assessed changes in the apoptosis-related genes BCL2, BAX, BCL2L12, FAS and CASPASE-3 in OVCAR-3 human ovarian cancer cells and BT-20 human breast cancer cells to provide an insight into the molecular mechanisms involved in the response of these cells to treatment with anticancer drugs and to assess their value as potential biomarkers of chemotherapy response in breast and ovarian cancer. Cells were treated with different chemotherapeutic drugs (cisplatin, carboplatin, doxorubicin, etoposide and taxol) and assessed for changes in the expression of apoptosis-related genes at the mRNA level. Total RNA was extracted, reverse-transcribed into cDNA and amplified by PCR using gene-specific primers. GAPDH was used as a housekeeping gene. Cytotoxicity was assessed by MTT assay. Both cancer cell lines responded differentially at the molecular level to the drug treatments. OVCAR-3 cells showed more pronounced sensitivity and changes compared to BT-20 cells at the mRNA level for different apoptosis-related genes, leading to cell and cancer type dependence in conjunction with drug dependence.

Knockdown of BCL2L12 leads to cisplatin resistance in MDA-MB-231 breast cancer cells

BCL2L12, a newly identified member of Bcl-2 family, contains a BH2 domain and a putative BH3 domain. It was found to be highly expressed in normal breast tissues, and was associated with favorable prognosis in breast cancer patients. Here, we reported that the mRNA levels of BCL2L12 and its transcript variant BCL2L12A could be upregulated upon cisplatin treatment in MDA-MB-231 breast cancer cells. Knockdown of BCL2L12 and BCL2L12A dramatically inhibited cisplatin-induced apoptosis. In contrast, ectopic expressions of each of the proteins promoted cisplatin-induced apoptosis. These results indicated that decreased expressions or loss of BCL2L12 and BCL2L12A may contribute to the cisplatin resistance in breast cancer patients. Furthermore, we found that cisplatin-induced downregulation of beta-catenin was partially suppressed in BCL2L12- and BCL2L12A-knocked down MDA-MB-231 cells, which indicated that knockdown of these two proteins may stabilize beta-catenin in cisplatin-induced apoptosis. In short, we proposed that BCL2L12 and BCL2L12A may play an important role in cisplatin-induced apoptosis in MDA-MB-231 breast cancer cells.

Reducing peritoneal vascular endothelial growth factor concentration and inhibiting cancer scattering in a mouse model of laparoscopy

OBJECTIVE

The objective of the study was to investigate the efficacy of early intraperitoneal (i.p.) paclitaxel administration in reducing vascular endothelial growth factor (VEGF) concentration in peritoneal fluid and preventing intraoperative cancer scattering during laparoscopy.

STUDY DESIGN

Nude mice were given i.p. ovarian cancer SKOV-3 xenografts to simulate intraoperative cancer dissemination and were assigned into concurrent- (day 0) and salvage-giving (day 5) treatment groups and nontreatment and nonxenografted groups.

RESULTS

The xenografted nontreatment group showed markedly increased peritoneal VEGF concentrations, whereas the paclitaxel (no-tumor) control group showed significantly reduced concentrations. In mice with cancer xenografts, both concurrent- and salvage-giving treatment groups showed significantly decreased peritoneal VEGF concentrations (P < .05), and the concurrent-giving group had significantly fewer implanted cancer nodules (P < .05), whereas the salvage-giving group had decreased total tumor weights (P < .05) compared with nontreatment. Total tumor weights were found closely correlated to peritoneal VEGF concentrations in a positive exponential relationship (P = .003, R(2) = 0.581).

CONCLUSION

Early treatment with IP paclitaxel significantly decreased the VEGF concentration in peritoneal fluid, which was associated with reduced implantation and growth of disseminated cancer cells after laparoscopy. These encouraging results suggest a useful strategy for future clinical applications.

Molecular profile of the BCL2 family of the apoptosis related genes in breast cancer cells after treatment with cytotoxic/cytostatic drugs

BCL2 (bcl-2) gene family members are important regulators of apoptosis. Increasing evidence supports their modulated expression in breast cancer cells and in many cases their relation to chemotherapy response, outcome, and overall prognosis, as well as their value as important potent therapeutic targets. Investigation and increased understanding of their transcriptional regulation and their specific roles in cancer progression and therapy response will be useful for focusing research on the development of novel therapies targeted against this gene family members' expression status. In the present review, we describe current knowledge of the molecular profile of the classical and novel members of the BCL2 family of genes as a response of breast cancer cells to cytotoxic/cytostatic drugs.

The effect of the polyadenylation inhibitor cordycepin on human Molt-4 and Daudi leukaemia and lymphoma cell lines

PURPOSE

Posttranscriptional modifications, such as polyadenylation, are very often implicated in the regulation and dysregulation of cell death, through regulation of the expression of specific genes. Based on the fact that an increasing number of adenosine analogues show their antiproliferative and cytotoxic activity via induction of apoptosis, we assessed the effect of cordycepin, a polyadenylation specific inhibitor, an adenosine analogue and a well-known chemotherapeutic drug, on two human leukemia and lymphoma cell lines.

METHODS

Cells were treated with the anticancer drug cordycepin and assessed for poly(A) polymerase (PAP) activity and isoforms by the highly sensitive PAP activity assay and western blotting, respectively. Induction of apoptosis was determined by endonucleosomal DNA cleavage, DAPI staining and Deltapsi(m) reduction, whereas cytotoxicity and cell cycle status were assessed by Trypan blue staining, MTT assay and flow cytometry.

RESULTS AND CONCLUSIONS

The results showed that the differentiated modulations of PAP in the two cell lines may be a result of the additive effect of the changes in cell cycle and apoptotic pathway induced.

The role of cordycepin in cancer treatment via induction or inhibition of apoptosis: implication of polyadenylation in a cell type specific manner

PURPOSE

Most anticancer drugs show their antiproliferative and cytotoxic activity via induction of apoptosis. In the present study we assessed the implication and role of cordycepin, a polyadenylation-specific inhibitor and a well-known chemotherapeutic drug, in apoptosis, induced by the anticancer drug etoposide.

METHODS

For this purpose, a variety of leukemia and lymphoma cell lines (U937, K562, HL-60, Daudi, Molt-4) were treated with the anticancer drugs etoposide and/or cordycepin and assessed for poly(A) polymerase (PAP) activity and isoforms by the highly sensitive PAP activity assay and western blotting, respectively. Induction of apoptosis was determined by endonucleosomal DNA cleavage, DAPI staining, caspase-6 activity assay and DeltaPsi m reduction, whereas cytotoxicity and cell cycle status were assessed by Trypan blue staining, MTT assay and flow cytometry.

RESULTS AND CONCLUSIONS

The results showed that PAP changes in all cell lines, in response to apoptosis induced by etoposide, in many cases even prior to hallmarks of apoptosis (endonucleosomal cleavage of DNA, DeltaPsi(m) reduction). A further elucidation to this apoptosis-polyadenylation correlation was added, by cell treatment with cordycepin, resulting in either suppression (U937, K562) or induction (HL-60) of the apoptotic process, according to the cell type. However, inhibition of polyadenylation did not influence the cell lines Daudi and Molt-4 used, where alternative apoptotic pathways are induced through cleavage of DNA into high molecular weight fragments.

The role of the mitochondria in mediating cytotoxicity of anti-cancer therapies

Optimal cytotoxic anticancer therapy, at the cellular level, requires effective and selective induction of cell death to achieve a net reduction of biomass of malignant tissues. Standard cytotoxic chemotherapeutics have been developed based on the observations that mitotically active cancer cells are more susceptible than quiescent normal cells to chromosomal, microtubular or metabolic poisons. More recent development of molecularly targeted drugs for cancer focuses on exploiting biological differentials between normal and transformed cells for selective eradication of cancers. The common thread of "standard" and "novel" cytotoxic drugs is their ability to activate the apoptosis-inducing machinery mediated by mitochondria, also known as the intrinsic death signaling cascade. The aim of this article is to provide an overview of the role of the mitochondria, an energy-generating organelle essential for life, in mediating death when properly activated by cytotoxic stresses.