BRCA1 and GADD45 mediated G2/M cell cycle arrest in response to antimicrotubule agents

GTN057, a komaroviquinone derivative, induced myeloma cells' death in vivo and inhibited c-MET tyrosine kinase

OBJECTIVE

Despite the development of newly developed drugs, most multiple myeloma (MM) patients with high-risk cytogenetic abnormalities such as t(4;14) or del17p relapse at anin early stage of their clinical course. We previously reported that a natural product,komaroviquinone (KQN), isolated from the perennial semi-shrub Dracocephalum komarovi, i.e., komaroviquinone (KQN) and its derivative GTN024 induced the apoptosis of MM cells by producing reactive oxygen species (ROS), but both exhibited significant hematological toxicity. Aim of this study is to clarify anti-tumor activity, safety and pharmacokinetics of GTN057, an optimization compound of KQN in vivo.

METHODS

ICR/SCID xenograft model of KMS11, a t(4;14) translocation-positive MM cell line, was used for in vivo study. Mice pharmacokinetics of GTN057 and the degradation products were analyzed by LC-MS/MS.

RESULTS

Herein, our in vitro experiments revealed that GTN057 is much less toxic to normal hematopoietic cells, induced the apoptosis of both MM cell lines andpatient samples, including those with high-risk cytogenetic changes. A xenograft model of a high-risk MM cell line demonstrated that GTN057 significantly delayed the tumor growth with no apparent hematological or systemic toxicities in vivo. The pathological examination of GTN057-treated tumors in vivoshowed revealed apoptosis of MM cells and anti-angiogenesis. In addition to the production of ROS, GTN057 inhibited the downstream signaling of c-MET, a receptor tyrosine kinase a receptor forand hepatocyte growth factor (HGF) receptor. Thus, GTN057 is less toxic and is able tomay be a candidate drug for treating MM patients, via multifunctional mechanisms. We have also extensively studied the pharmacologyical analysis of GTN057. The metabolites of GTN057, (e.g.,such as GTN054), may also have anti-tumorantitumor activity.

CONCLUSION

Natural products or and their derivatives can could be good sources of antineoplastic drugs even for high-risk cancer.

Analgesic effects and metabolome analyses of laser- and electro-acupuncture combined therapies in paclitaxel-induced neuropathic pain model

Introduction

Allodynia, which can be induced by paclitaxel administration, is the presence of pain as a result of a stimulus that does not usually provoke pain. Many studies have investigated the analgesic efficacy of acupuncture, including laser acupuncture (LA) and electroacupuncture (EA). Although pain-related diseases are relatively common, few studies have analyzed the analgesic effects and mechanisms of LA combined with EA. The purpose of this study was to investigate the therapeutic effect and mechanism of manual acupuncture (MA), EA, LA, and combined therapy (LA + EA) in a paclitaxel-induced allodynia rat model.

Methods

A total of 56 rats were classified into eight groups: a normal (Nor, n = 7), a control (Con, n = 7), an MA (n = 7), an EA (n = 7), a 650-nm LA (650LA, n = 7), an 830-nm LA (830LA, n = 7), a 650-nm LA combined with EA (650LA + EA, n = 7), and an 830-nm LA combined with EA group (830LA + EA, n = 7). Allodynia was induced by intraperitoneal injection of 2 mg/kg of paclitaxel every other day for a total of four times except the Nor group. Acupuncture treatments were conducted at the points of Jungwan (CV12) and Joksamni (ST36) once every other day for 6 min, for a total of nine times. Withdrawal response reaction times and force intensity of the foot were measured before the start of the experiment, after the 4th paclitaxel administration (day 8), and after the 9th and last treatment (day 15). On the 16th day, mRNA and protein expression in the spinal nerves was assessed, and a metabolome analysis of the animals' feces was performed.

Results and discussion

Our analyses show that 650LA + EA treatment resulted in an upregulation of protein expression related to pain relief and nerve regeneration, whereas 830LA + EA treatment led to significant changes in metabolomes. This study demonstrates that a combination treatment of EA and LA can suppress allodynia and promote upregulation of protein expression related to nerve regeneration and is effective in changing the intestinal microbiome. Further large-scale research is required to assess the exact mechanism underlying the therapeutic effect of this combination treatment in pain-related diseases.

Self-assembled and pH-responsive polymeric nanomicelles impart effective delivery of paclitaxel to cancer cells

Chemotherapy is an essential component of breast cancer therapy, but it is associated with serious side effects. Herein, a pluronic F68-based pH-responsive, and self-assembled nanomicelle system was designed to improve the delivery of paclitaxel (PTX) to breast cancer cells. Two pH-responsive pluronic F68-PTX conjugates i.e. succinoyl-linked conjugate (F68-SA-PTX) and cis-aconityl-linked conjugate (F68-CAA-PTX) were designed to respond the varying pH-environment in tumour tissue. Although both the linkers showed pH-sensitivity, the F68-CAA-PTX exhibited superior pH-sensitivity over the F68-SA-PTX and achieved a more selective release of PTX from the self-assembled nanomicelles. The prepared nanomicelles were characterized by dynamic light scattering, transmittance electron microscopy, differential scanning calorimetry and powder X-ray diffraction techniques. The anticancer activity of prepared nanomicelles and pure PTX were evaluated by 2D cytotoxicity assay against breast cancer cell line MDA-MB-231 and in the real tumour environments i.e. 3D tumor spheroids of MDA-MB-231 cells. The highest cytotoxicity effect of PTX was observed with F68-CAA-PTX nanomicelles followed by F68-SA-PTX and free PTX. Further, the F68-CAA-PTX nanomicelles also induced significant apoptosis with a combination of increase in ROS generation, decrease in the depolarisation of MMP and G2/M cell cycle arrest. These observed results provide a new insight for breast cancer treatment using pluronic nanomicelles.

Genetic Mutation Analysis in Small Cell Lung Cancer by a Novel NGS-Based Targeted Resequencing Gene Panel and Relation with Clinical Features

Background

Small cell lung cancer (SCLC) is an aggressive and invasive malignancy that presents at advanced clinical stage with no more effective treatments. Development of a method for its early detection would be useful, also new therapeutic target need to be discovered; however, there is a lack of information about its oncogenic driver gene mutations.

Objectives

We aim to identify the SCLC-related genomic variants that associate with clinical staging and serum protein biomarkers observed in other types of lung cancer.

Methods

We screened formalin-fixed paraffin-embedded (FFPE) biopsy tissues of 32 Chinese SCLC patients using the 303 oncogenic driver gene panel generated by Tiling PCR amplification sequencing (tPAS) and analyzed the patients' corresponding serum protein levels of CYFRA21-1 CEA, NSE, and SCCA.

Results

In total, we found 147 SCLC-related mutant genes, among these, three important genes (TP53, RB1, KMT2D) as well as five novel genes LRRK2, BRCA1, PTCH1, ARID2, and APC that altogether occurred in 90% of patients. Furthermore, increased mutations to 6 genes (WT1, NOTCH1, EPHA3, KDM6A, SETD2, ACVR1B) significantly associated with higher serum NSE levels (P = 0.0016) and higher clinical stages II + III compared to stage I (P = 0.06).

Conclusions

Our panel is relatively reliable in detecting the oncogenic mutations of Chinese SCLC patients. Based on our findings, it may be possible to combine SCLC-related mutations and serum NSE for a simple detection of clinical staging.

Mechanisms of Taxane Resistance

The taxane family of chemotherapy drugs has been used to treat a variety of mostly epithelial-derived tumors and remain the first-line treatment for some cancers. Despite the improved survival time and reduction of tumor size observed in some patients, many have no response to the drugs or develop resistance over time. Taxane resistance is multi-faceted and involves multiple pathways in proliferation, apoptosis, metabolism, and the transport of foreign substances. In this review, we dive deeper into hypothesized resistance mechanisms from research during the last decade, with a focus on the cancer types that use taxanes as first-line treatment but frequently develop resistance to them. Furthermore, we will discuss current clinical inhibitors and those yet to be approved that target key pathways or proteins and aim to reverse resistance in combination with taxanes or individually. Lastly, we will highlight taxane response biomarkers, specific genes with monitored expression and correlated with response to taxanes, mentioning those currently being used and those that should be adopted. The future directions of taxanes involve more personalized approaches to treatment by tailoring drug-inhibitor combinations or alternatives depending on levels of resistance biomarkers. We hope that this review will identify gaps in knowledge surrounding taxane resistance that future research or clinical trials can overcome.

BRCA1/MAD2L1 Deficiency Disrupts the Spindle Assembly Checkpoint to Confer Vinorelbine Resistance in Mesothelioma

Mesothelioma is a universally lethal cancer lacking effective therapy. The spindle poison vinorelbine exhibits clinical activity in the relapsed setting, and in preclinical models requires BRCA1 to initiate apoptosis. However, the mechanisms underlying this regulation and the clinical implications have not been explored. Here, we show that BRCA1 silencing abrogated vinorelbine-induced cell-cycle arrest, recruitment of BUBR1 to kinetochores, and apoptosis. BRCA1 silencing led to codepletion of MAD2L1 at the mRNA and protein levels consistent with its status as a transcriptional target of BRCA1 Silencing of MAD2L1 phenocopied BRCA1 and was sufficient to confer resistance to vinorelbine. This was recapitulated in cell lines selected for resistance to vinorelbine, which acquired loss of both BRCA1 and MAD2L1 expression. Following ex vivo vinorelbine in 20 primary tumor explants, apoptotic response rate was 59% in BRCA1/MAD2L1-positive explants compared with 0% in BRCA1/MAD2L1-negative explants. In 48 patients, BRCA1 and/or MAD2L1 loss of expression was not prognostic; however, in a subset of patients treated with vinorelbine, survival was shorter for patients lacking BRCA1/MAD2L1 expression compared with double-positive patients (5.9 vs. 36.7 months, P = 0.03). Our data implicate BRCA1/MAD2L1 loss as a putative predictive marker of resistance to vinorelbine in mesothelioma and warrant prospective clinical evaluation.

BRCA Genes: The Role in Genome Stability, Cancer Stemness and Therapy Resistance

Carcinogenesis is a multistep process, and tumors frequently harbor multiple mutations regulating genome integrity, cell division and death. The integrity of cellular genome is closely controlled by the mechanisms of DNA damage signaling and DNA repair. The association of breast cancer susceptibility genes BRCA1 and BRCA2 with breast and ovarian cancer development was first demonstrated over 20 years ago. Since then the germline mutations within these genes were linked to genomic instability and increased risk of many other cancer types. Genomic instability is an engine of the oncogenic transformation of non-tumorigenic cells into tumor-initiating cells and further tumor evolution. In this review we discuss the biological functions of BRCA1 and BRCA2 genes and the role of BRCA mutations in tumor initiation, regulation of cancer stemness, therapy resistance and tumor progression.

Bag-1 silencing enhanced chemotherapeutic drug-induced apoptosis in MCF-7 breast cancer cells affecting PI3K/Akt/mTOR and MAPK signaling pathways

The multifunctional anti-apoptotic Bag-1 protein has important roles in apoptosis, proteasome-mediated degradation, transcriptional regulation, and intracellular signaling. Bag-1 promotes cell survival and proliferation, and is overexpressed in breast cancer. Therefore, Bag-1-targeted therapy might be a promising strategy to treat breast cancer. However, the effects of Bag-1 silencing in combination with conventional chemotherapeutic drugs on cell viability and major signaling pathways have not yet been fully investigated in breast cancer cells. In this study, we investigated the cytotoxic effects of Bag-1 silencing, alone and in combination with cisplatin or paclitaxel treatment, in MCF-7 breast cancer cells. Bag-1 knockdown by shRNA or siRNA transfection sensitized MCF-7 cells to apoptosis induced by cisplatin or paclitaxel. Combination of Bag-1 silencing and drug treatment more potently downregulated the pro-survival PI3K/Akt/mTOR and p44/42 mitogen activated protein kinase (MAPK) pathways, and more potently upregulated the stress-activated p38 and SAPK/JNK MAPK pathways. Bag-1-silenced drug-treated cells had also highly reduced proliferative capacity, downregulated cyclin-cyclin dependent kinase complexes and upregulated tumor suppressors p21 and Rb. These results overall indicated that Bag-1 silencing enhanced cisplatin- or paclitaxel-induced cytotoxicity through multiple pathways. In conclusion, Bag-1 targeted therapy might enhance the therapeutic potential of conventional anti-cancer drugs in the treatment of breast cancer.

Association between EGFR mutation and expression of BRCA1 and RAP80 in non-small cell lung cancer

Association between the epithelial growth factor receptor (EGFR) mutation and the expression of breast cancer 1 (BRCA1) and receptor-associated protein 80 (RAP80) in non-small cell lung cancer (NSCLC) was studied. From September 2014 to September 2016, 51 patients with NSCLC who were hospitalized in Department of Thoracic Surgery in The Affiliated Jiangyin Hospital of Southeast University Medical College and underwent biopsy or operation were selected. The pathological changes of lung tissue were detected by hematoxylin and eosin histopathological staining. The fluorescent expression of BRCA1 and RAP80 protein in the two groups was determined by immunofluorescence staining. Reverse transcriptase polymerase chain reaction method and western blot analysis were used to detect BRCA1 and RAP80 mRNA and protein expression. Then the EGFR gene mutation was detected and analyzed. The results show that non-small cell lung cancer has an association with smoking. Compared with the control, the lung tissue structure of the NSCLC group was damaged. The protein fluorescence expression of BRCA1 and RAP80 in non-small cell lung cancer group was significantly increased. The expression of BRCA1 and RAP80 mRNA and protein in NSCLC group was significantly increased. The difference in expression of BRCA1 and RAP80 in the control and the non-small cell lung cancer group was statistically significant (P<0.05). EGFR gene mutations detected 14 of the 51 patients with genetic mutations. Non-small cell lung cancer and smoking have certain relevance, and BRCA1 and RAP80 expression in the development and progression of NSCLC has a close relationship. EGFR mutation in non-small cell lung cancer significantly related to the mutation of EGFR and BRCA1 and RAP80 gene expression plays an important role in the diagnosis and treatment of NSCLC.

Cabazitaxel is more active than first-generation taxanes in ABCB1(+) cell lines due to its reduced affinity for P-glycoprotein

PURPOSE

The primary aim of this study was to determine cabazitaxel's affinity for the ABCB1/P-glycoprotein (P-gp) transporter compared to first-generation taxanes.

METHODS

We determined the kinetics of drug accumulation and retention using [¹⁴C]-labeled taxanes in multidrug-resistant (MDR) cells. In addition, membrane-enriched fractions isolated from doxorubicin-selected MES-SA/Dx5 cells were used to determine sodium orthovanadate-sensitive ATPase stimulation after exposure to taxanes. Custom [³H]-azido-taxane analogues were synthesized for the photoaffinity labeling of P-gp.

RESULTS

The maximum intracellular drug concentration was achieved faster with [¹⁴C]-cabazitaxel (5 min) than [¹⁴C]-docetaxel (15-30 min). MDR cells accumulated twice as much cabazitaxel than docetaxel, and these levels could be restored to parental levels in the presence of the P-gp inhibitor PSC-833 (valspodar). Efflux in drug-free medium confirmed that MDR cells retained twice as much cabazitaxel than docetaxel. There was a strong association (r² = 0.91) between the degree of taxane resistance conferred by P-gp expression and the accumulation differences observed with the two taxanes. One cell model expressing low levels of P-gp was not cross-resistant to cabazitaxel while demonstrating modest resistance to docetaxel. Furthermore, there was a 1.9 × reduction in sodium orthovanadate-sensitive ATPase stimulation resulting from treatment with cabazitaxel compared to docetaxel. We calculated a dissociation constant (Kd) value of 1.7 µM for [³H]-azido-docetaxel and ~ 7.5 µM for [³H]-azido-cabazitaxel resulting in a 4.4 × difference in P-gp labeling, and cold docetaxel was a more effective competitor than cabazitaxel.

CONCLUSION

Our studies confirm that cabazitaxel is more active in ABCB1(+) cell models due to its reduced affinity for P-gp compared to docetaxel.

Analysis of resistance-associated gene expression in docetaxel-resistant prostate cancer cells

Docetaxel-based chemotherapy is the standard treatment for metastatic castration-resistant prostate cancer (CRPC). However, a number of patients with metastatic CRPC are refractory to docetaxel or develop docetaxel resistance. The underlying molecular mechanisms of docetaxel resistance remain unclear, which is a significant burden to the management of metastatic prostate cancer. In the present study, the differential gene expression between docetaxel-sensitive (PC3) and docetaxel-resistant (PC3DR2) prostate cancer cells was identified using DNA microarrays, western blot analysis and reverse transcription-quantitative polymerase chain reaction. Of the genes implicated in cancer-associated pathways, insulin-like growth factor 1 receptor, DBF4 homolog, sterile α motif and leucine zipper-containing kinase AZK, Patched 1, serpin peptidase inhibitor, clade E, member 1 and breast cancer 2 (BRCA2) were >3-fold upregulated in PC3DR2 cells compared with PC3 cells. BRCA2 knockdown with small interfering RNA decreased the docetaxel resistance of PC3DR2 cells. These results suggest that BRCA2 serves an important role in the docetaxel resistance of prostate cancer cells. In addition, BRCA2 modulation may be a strategy to partially reverse docetaxel resistance in prostate cancer.

Low RAP80 mRNA expression correlates with shorter survival in sporadic high-grade serous ovarian carcinoma

OBJECTIVE

Homologous recombination (HR) is frequently impaired in sporadic high-grade serous ovarian carcinoma (sHGSOC) due to deficiencies in BRCA1/2 genes, a situation associated with hypersensitivity to platinum compounds. Alterations in other genes can also cause HR deficiency. Preclinical data show that RAP80 is an HR-pathway-related gene that influences BRCA1 activity. RAP80 has been reported to affect outcome in some solid neoplasms. This study investigates the role of RAP80 in sHGSOC survival.

METHODS

mRNA expression of RAP80 was analyzed in tumor samples from 35 patients who postoperatively received standard platinum-based chemotherapy. The effects of RAP80 expression on progression-free survival (PFS) and overall survival (OS) were examined by means of Cox regressions. The clinical variables known to have prognostic value (FIGO stage, residual disease at surgery, and debulking surgery) were included as covariates in the analysis. BRCA1 was analyzed given the moderate correlations with RAP80.

RESULTS

Median follow-up, PFS and OS were 61.3, 20.2 and 62.8 months, respectively. Low RAP80 expression levels were associated with shorter PFS (HR = 1.449, p = 0.007) and OS (HR = 1.331, p = 0.047).

CONCLUSIONS

This is the first study to show a potential prognostic role of RAP80 expression in patients with HGSOC. The results suggest that HR deficiency due to low RAP80 expression is not associated with hypersensitivity to platinum compounds in sHGSOC.

Low Doses of Cisplatin Induce Gene Alterations, Cell Cycle Arrest, and Apoptosis in Human Promyelocytic Leukemia Cells

Cisplatin is a known antitumor drug, but its mechanisms of action are not fully elucidated. In this research, we studied the anticancer potential of cisplatin at doses of 1, 2, or 3 µM using HL-60 cells as a test model. We investigated cisplatin effects at the molecular level using RNA sequencing, cell cycle analysis, and apoptotic assay after 24, 48, 72, and 96 hours of treatment. The results show that many genes responsible for molecular and cellular functions were significantly altered. Cisplatin treatment also caused the cells to be arrested at the DNA synthesis phase, and as the time increases, the cells gradually accumulated at the sub-G1 phase. Also, as the dose increases, a significant number of cells entered into the apoptotic and necrotic stages. Altogether, the data show that low doses of cisplatin significantly impact the viability of HL-60 cells, through modulation of gene expression, cell cycle, and apoptosis.

Disruption of DNA Damage-Response by Propyl Gallate and 9-Aminoacridine

The DNA-damage response (DDR) protects the genome from various types of endogenous and exogenous DNA damage, and can itself be a target of certain chemicals that give rise to chromosomal aberrations. Here, we developed a screening method to detect inhibition of Mediator of DNA damage Checkpoint 1 (MDC1) foci formation (the Enhanced Green Fluorescent Protein (EGFP)-MDC1 foci formation-inhibition assay) using EGFP-MDC1-expressing human cells. The assay identified propyl gallate (PG) and 9-aminoacridine (9-AA) as inhibitors of camptothecin (CPT)-induced MDC1 foci formation. We demonstrated that the inhibition of CPT-induced MDC1 foci formation by PG was caused by the direct suppression of histone H2AX phosphorylation at Ser139 (γH2AX), which is required for MDC1 foci formation, by quantifying γH2AX in cells and in vitro 9-AA also directly suppressed H2AX Ser139-phosphorylation in vitro but the concentration was much higher than that required to suppress CPT-induced MDC1 foci formation in cells. Consistent with these findings, PG and 9-AA both suppressed CPT-induced G2/M cell-cycle arrest and increased the number of abnormal nuclei. Our results suggest that early DDR-inhibitory effects of PG and 9-AA contribute to their chromosome-damaging potential, and that the EGFP-MDC1 foci formation-inhibition assay is useful for detection of and screening for H2AX Ser139-phosphorylation-inhibitory effects of chemicals.

Reversal of Multidrug Resistance by the Chinese Medicine Yiqi Jianpi Huaji Decoction and the Mechanism of Action in Human Gastric Cancer SGC7901/VCR Cells

Yiqi Jianpi Huaji Decoction (YJHD), a traditional Chinese medicinal formula composed of twelve ingredients, has recently been reported to have a good clinical curative effect. The purpose of the present study was to evaluate the effects of YJHD on SGC7901/VCR gastric cancer cells and to elucidate the possible mechanism of action. First, the effects of a low dose of YJHD in combination with chemotherapeutic agents on SGC7901/VCR cells were assessed using the CCK-8 assay and flow cytometry, and the effects of YJHD on genes and proteins involved in drug resistance (MDR1, MRP, TUBB3, STMN1, and TS) were evaluated. Furthermore, transfection of SGC7901/VCR cells with siRNAs targeting these genes inhibited their expression, and the efficacy of vincristine against the cells was dramatically improved in vitro when these genes were silenced. These results demonstrate that low-dose YJHD inhibited cell proliferation, induced apoptosis, reversed MDR, and increased sensitivity to chemotherapeutic agents in vitro by downregulating P-gp, MRP, TUBB3, and STMN1 expression. MDR can be reversed by siRNAs targeting genes involved in MDR, and this strategy for cancer treatment should be evaluated in future studies.

Mechanisms of resistance to cabazitaxel

We studied mechanisms of resistance to the novel taxane cabazitaxel in established cellular models of taxane resistance. We also developed cabazitaxel-resistant variants from MCF-7 breast cancer cells by stepwise selection in drug alone (MCF-7/CTAX) or drug plus the transport inhibitor PSC-833 (MCF-7/CTAX-P). Among multidrug-resistant (MDR) variants, cabazitaxel was relatively less cross-resistant than paclitaxel and docetaxel (15- vs. 200-fold in MES-SA/Dx5 and 9- vs. 60-fold in MCF-7/TxT50, respectively). MCF-7/TxTP50 cells that were negative for MDR but had 9-fold resistance to paclitaxel were also 9-fold resistant to cabazitaxel. Selection with cabazitaxel alone (MCF-7/CTAX) yielded 33-fold resistance to cabazitaxel, 52-fold resistance to paclitaxel, activation of ABCB1, and 3-fold residual resistance to cabazitaxel with MDR inhibition. The MCF-7/CTAX-P variant did not express ABCB1, nor did it efflux rhodamine-123, BODIPY-labeled paclitaxel, and [(3)H]-docetaxel. These cells are hypersensitive to depolymerizing agents (vinca alkaloids and colchicine), have reduced baseline levels of stabilized microtubules, and impaired tubulin polymerization in response to taxanes (cabazitaxel or docetaxel) relative to MCF-7 parental cells. Class III β-tubulin (TUBB3) RNA and protein were elevated in both MCF-7/CTAX and MCF-7/CTAX-P. Decreased BRCA1 and altered epithelial-mesenchymal transition (EMT) markers are also associated with cabazitaxel resistance in these MCF-7 variants, and may serve as predictive biomarkers for its activity in the clinical setting. In summary, cabazitaxel resistance mechanisms include MDR (although at a lower level than paclitaxel and docetaxel), and alterations in microtubule dynamicity, as manifested by higher expression of TUBB3, decreased BRCA1, and by the induction of EMT.

The predictive value of 53BP1 and BRCA1 mRNA expression in advanced non-small-cell lung cancer patients treated with first-line platinum-based chemotherapy

Platinum-based chemotherapy is the standard first-line treatment for non-oncogene-addicted non-small cell lung cancers (NSCLCs) and the analysis of multiple DNA repair genes could improve current models for predicting chemosensitivity. We investigated the potential predictive role of components of the 53BP1 pathway in conjunction with BRCA1. The mRNA expression of BRCA1, MDC1, CASPASE3, UBC13, RNF8, 53BP1, PIAS4, UBC9 and MMSET was analyzed by real-time PCR in 115 advanced NSCLC patients treated with first-line platinum-based chemotherapy. Patients expressing low levels of both BRCA1 and 53BP1 obtained a median progression-free survival of 10.3 months and overall survival of 19.3 months, while among those with low BRCA1 and high 53BP1 progression-free survival was 5.9 months (P <0.0001) and overall survival was 8.2 months (P=0.001). The expression of 53BP1 refines BRCA1-based predictive modeling to identify patients most likely to benefit from platinum-based chemotherapy.

Apoptosis and molecular targeting therapy in cancer

Apoptosis is the programmed cell death which maintains the healthy survival/death balance in metazoan cells. Defect in apoptosis can cause cancer or autoimmunity, while enhanced apoptosis may cause degenerative diseases. The apoptotic signals contribute into safeguarding the genomic integrity while defective apoptosis may promote carcinogenesis. The apoptotic signals are complicated and they are regulated at several levels. The signals of carcinogenesis modulate the central control points of the apoptotic pathways, including inhibitor of apoptosis (IAP) proteins and FLICE-inhibitory protein (c-FLIP). The tumor cells may use some of several molecular mechanisms to suppress apoptosis and acquire resistance to apoptotic agents, for example, by the expression of antiapoptotic proteins such as Bcl-2 or by the downregulation or mutation of proapoptotic proteins such as BAX. In this review, we provide the main regulatory molecules that govern the main basic mechanisms, extrinsic and intrinsic, of apoptosis in normal cells. We discuss how carcinogenesis could be developed via defective apoptotic pathways or their convergence. We listed some molecules which could be targeted to stimulate apoptosis in different cancers. Together, we briefly discuss the development of some promising cancer treatment strategies which target apoptotic inhibitors including Bcl-2 family proteins, IAPs, and c-FLIP for apoptosis induction.

DNA repair pathways and their therapeutic potential in lung cancer

SUMMARY: 

Lung cancer is the leading cause of cancer-related mortality. According to WHO, 1.37 million deaths occur globally each year as a result of this disease. More than 70% of these cases are associated with prior tobacco consumption and/or cigarette smoking, suggesting a direct causal relationship. The development and progression of lung cancer and other malignancies involves the loss of genetic stability, resulting in acquisition of cumulative genetic changes; this affords the cell increased malignant potential. As such, an understanding of the mechanisms through which these events may occur will potentially allow for development of new anticancer therapies. This review will address the association between lung cancer and genetic instability, with a central focus on genetic mutations in the DNA damage repair pathways. In addition, we will discuss the potential clinical exploitation of these pathways, both in terms of biomarker staging, as well as through direct therapeutic targeting.

Anti-tumor activity of Eurycoma longifolia root extracts against K-562 cell line: in vitro and in vivo study

Eurycoma longifolia Jack has been widely used in traditional medicine for its antimalarial, aphrodisiac, anti-diabetic, antimicrobial and anti-pyretic activities. Its anticancer activity has also been recently reported on different solid tumors, however no anti-leukemic activity of this plant has been reported. Thus the present study assesses the in vitro and in vivo anti-proliferative and apoptotic potentials of E. longifolia on K-562 leukemic cell line. The K-562 cells (purchased from ATCC) were isolated from patients with chronic myelocytic leukemia (CML) were treated with the various fractions (TAF273, F3 and F4) of E. longifolia root methanolic extract at various concentrations and time intervals and the anti-proliferative activity assessed by MTS assay. Flow cytometry was used to assess the apoptosis and cell cycle arrest. Nude mice injected subcutaneously with 10⁷ K-562 cells were used to study the anti-leukemic activity of TAF273 in vivo. TAF273, F3 and F4 showed various degrees of growth inhibition with IC50 values of 19, 55 and 62 µg/ml, respectively. TAF273 induced apoptosis in a dose and time dependent manner. TAF273 arrested cell cycle at G1and S phases. Intraperitoneal administration of TAF273 (50 mg/kg) resulted in a significant growth inhibition of subcutaneous tumor in TAF273-treated mice compared with the control mice (P = 0.024). TAF273 shows potent anti-proliferative activity in vitro and in vivo models of CML and therefore, justifies further efforts to define more clearly the potential benefits of using TAF273 as a novel therapeutic strategy for CML management.

Predictive value of BRCA1, ERCC1, ATP7B, PKM2, TOPOI, TOPΟ-IIA, TOPOIIB and C-MYC genes in patients with small cell lung cancer (SCLC) who received first line therapy with cisplatin and etoposide

BACKGROUND

The aim of the study was to evaluate the predictive value of genes involved in the action of cisplatin-etoposide in Small Cell Lung Cancer (SCLC).

METHODS

184 SCLC patients' primary tumour samples were analyzed for ERCCI, BRCA1, ATP7B, PKM2 TOPOI, TOPOIIA, TOPOIIB and C-MYC mRNA expression. All patients were treated with cisplatin-etoposide.

RESULTS

The patients' median age was 63 years and 120 (65%) had extended stage, 75 (41%) had increased LDH serum levels and 131 (71%) an ECOG performance status was 0-1. Patients with limited stage, whose tumours expressed high ERCC1 (p=0.028), PKM2 (p=0.046), TOPOI (p=0.008), TOPOIIA (p=0.002) and TOPOIIB (p<0.001) mRNA had a shorter Progression Free Survival (PFS). In limited stage patients, high expression of ERCC1 (p=0.014), PKM2 (p=0.026), TOPOIIA (p=0.021) and TOPOIIB (p=0.019) was correlated with decreased median overall survival (mOS) while in patients with extended stage, only high TOPOIIB expression had a negative impact on Os (p=0.035). The favorable expression signature expression signature (low expression of ERCC1, PKM2, TOPOIIA and TOPOIIB) was correlated with significantly better PFS and Os in both LS-SCLC (p<0.001 and p=0.007, respectively) and ES-SCLC (p=0.007 and (p=0.011, respectively) group. The unfavorable expression signature was an independent predictor for poor PFS (HR: 3.18; p=0.002 and HR: 3.14; p=0.021) and Os (HR: 4.35; p=0.001and HR: 3.32; p=0.019) in both limited and extended stage, respectively.

CONCLUSIONS

Single gene's expression analysis as well as the integrated analysis of ERCC1, PKM2, TOPOIIA and TOPOIIB may predict treatment outcome in patients with SCLC. These findings should be further validated in a prospective study.

Differential chemotherapeutic sensitivity for breast tumors with "BRCAness": a review

BRCA1 or BRCA2 mutations predispose to cancer development, primarily through their loss of role in the repair of DNA double-strand breaks. They play a key role in homologous recombination repair, which is a conservative, error-free DNA repair mechanism. When mutated, other alternative, error-prone mechanisms for DNA repair take over, leading to genomic instability. Somatic mutations are rare in sporadic breast tumors, but expression of BRCA1 and BRCA2 genes can be downregulated in other mechanistic ways. These tumors have similar features in terms of their phenotypic and genotypic profiles, which are normally regulated by these genes, and mutations lead to defective DNA repair capacity, called "BRCAness." Attempts have been made to exploit this differentially expressed feature between tumors and normal tissues by treatment with DNA-damaging chemotherapy agents. Cells with this functional BRCA deficiency should be selectively susceptible to DNA-damaging drugs. Preclinical and early clinical (primarily retrospective) evidence supports this approach. In contrast, there is emerging evidence of relative resistance of tumors containing BRCA1 or BRCA2 mutations (or BRCAness) to taxanes. In this review, we summarize the data supporting differential chemotherapeutic sensitivity on the basis of defective DNA repair. If confirmed with available, clinically applicable techniques, this differential chemosensitivity could lead to treatment choices in breast cancer that have a more individualized biologic basis.

Unprecedented inhibition of tubulin polymerization directed by gold nanoparticles inducing cell cycle arrest and apoptosis

The effect of gold nanoparticles (AuNPs) on the polymerization of tubulin has not been examined till now. We report that interaction of weakly protected AuNPs with microtubules (MTs) could cause inhibition of polymerization and aggregation in the cell free system. We estimate that single citrate capped AuNPs could cause aggregation of ∼10(5) tubulin heterodimers. Investigation of the nature of inhibition of polymerization and aggregation by Raman and Fourier transform-infrared (FTIR) spectroscopies indicated partial conformational changes of tubulin and microtubules, thus revealing that AuNP-induced conformational change is the driving force behind the observed phenomenon. Cell culture experiments were carried out to check whether this can happen inside a cell. Dark field microscopy (DFM) combined with hyperspectral imaging (HSI) along with flow cytometric (FC) and confocal laser scanning microscopic (CLSM) analyses suggested that AuNPs entered the cell, caused aggregation of the MTs of A549 cells, leading to cell cycle arrest at the G0/G1 phase and concomitant apoptosis. Further, Western blot analysis indicated the upregulation of mitochondrial apoptosis proteins such as Bax and p53, down regulation of Bcl-2 and cleavage of poly(ADP-ribose) polymerase (PARP) confirming mitochondrial apoptosis. Western blot run after cold-depolymerization revealed an increase in the aggregated insoluble intracellular tubulin while the control and actin did not aggregate, suggesting microtubule damage induced cell cycle arrest and apoptosis. The observed polymerization inhibition and cytotoxic effects were dependent on the size and concentration of the AuNPs used and also on the incubation time. As microtubules are important cellular structures and target for anti-cancer drugs, this first observation of nanoparticles-induced protein's conformational change-based aggregation of the tubulin-MT system is of high importance, and would be useful in the understanding of cancer therapeutics and safety of nanomaterials.

Pharmacogenetics of conventional chemotherapy in non-small-cell lung cancer: a changing landscape?

Pharmacogenetics might be used to select patients who may benefit from specific chemotherapy that best matches the individual and tumor genetic profile, thus allowing maximum activity and minimal toxicity. Even if most studies in non-small-cell lung cancer yielded contradictory results, several potential biomarkers for sensitivity/resistance to platinum compounds, gemcitabine, taxanes and pemetrexed have been proposed. However, these markers need to be validated within larger prospective randomized trials of customized chemotherapy in homogeneous populations. Other critical points include the optimization/standardization of technical procedures, and further studies to unravel the extremely complex regulation of gene function. From this perspective, the evaluation of key factors influencing genotype-phenotype relationships, such as miRNAs, and functional studies to clarify pharmacokinetic/pharmacodynamic interactions, are fundamental for the pharmacogenetic optimization of cancer chemotherapy. Finally, limitation of the traditional pharmacogenetic approach relying only on candidate genes suspected of affecting drug response is now being overcome by the use of novel genome-wide studies.

The involvement of WT1 in the regulation of GADD45a in response to genotoxic stress

Expression of the human GADD45a gene is increased in TK6 cells exposed to mutagens, clastogens and aneugens. It is known to be regulated through both p53-dependent and p53-independent pathways and WT1 has been implicated in both cases. This article reports an investigation into the effect that mutations in the WT1 and p53 response elements of the gene have on GADD45a expression. This was conducted in both p53 wild-type (TK6) and mutant (WI-L2-NS) human B lymphoblastoid cell lines. Gene expression was monitored using a GADD45a-green fluorescent protein reporter assay. Mutant cell lines were exposed to the mechanistically diverse genotoxins methyl methanesulphonate, cisplatin and mitomycin C (direct acting), hydroxyurea, aphidicolin and 5'fluorouracil (inhibitors of nucleotide/DNA synthesis) and benomyl (aneugen). In all cases, the induction of the reporter was reduced in the mutants compared with wild-type. These results provide experimental evidence for the implied role of WT1 in both p53-dependent and p53-independent pathways of GADD45a regulation and further insight into the mechanism of GADD45a induction by genotoxins.

BRCA1 mRNA expression as a predictive and prognostic marker in advanced esophageal squamous cell carcinoma treated with cisplatin- or docetaxel-based chemotherapy/chemoradiotherapy

BACKGROUND

The molecular backgrounds that determine therapeutic effectiveness in esophageal cancer remain largely unknown. Breast cancer susceptibility gene 1 (BRCA1) expression has been found to switch the response to cisplatin- or paclitaxel-based chemotherapy. It remains unclear how variations in BRCA1 expression influence clinical outcomes in esophageal cancer.

PATIENTS AND METHODS

Quantitative real-time polymerase chain reaction (qPCR) was performed to examine BRCA1 mRNA expressions in paraffin-embedded specimens from 144 patients with advanced or metastatic esophageal squamous cell carcinoma who received cisplatin- or docetaxel-based first-line treatments.

RESULTS

Low BRCA1 mRNA expression correlated with increased response rate (RR; P = 0.025 and 0.017, respectively) and median overall survival (mOS; P = 0.002 and P<0.001, respectively) in cisplatin-based chemotherapy or chemoradiotherapy group and also correlated with decreased RR (P = 0.017 and 0.024, respectively) and mOS (both P<0.001) in docetaxel-based chemotherapy or chemoradiotherapy group. Multivariate analysis revealed that low BRCA1 expression was an independent prognostic factor in cisplatin-based chemotherapy (HR 0.29; 95%CI 0.12-0.71; P = 0.007) or chemoradiotherapy (HR 0.12; 95%CI 0.04-0.37; P<0.001) group and higher risk for mortality in docetaxel-based chemotherapy (HR 5.02; 95%CI 2.05-12.28; P<0.001) or chemoradiotherapy (HR 7.02; 95%CI 2.37-27.77; P<0.001) group.

CONCLUSIONS

BRCA1 mRNA expression could be used as a predictive and prognostic marker in esophageal cancer who underwent first-line cisplatin- or docetaxel-based treatments.

Analysis of ZNF350/ZBRK1 promoter variants and breast cancer susceptibility in non-BRCA1/2 French Canadian breast cancer families

ZNF350/ZBRK1 is a transcription factor, which associates with BRCA1 to co-repress GADD45A to regulate DNA damage repair, and the expression of ZNF350 is altered in different human carcinomas. In a previous study, we identified ZNF350 genomic variants potentially involved in breast cancer susceptibility in high-risk non-BRCA1/2 breast cancer individuals, which pointed toward a potential association for variants in the 5'-UTR and promoter regions. Therefore, direct sequencing was undertaken and identified 12 promoter variants, whereas haplotype analyses put in evidence four common haplotypes with a frequency>2%. However, based on their frequency observed in breast cancer and unrelated healthy individuals, these are not statistically associated with breast cancer risk. Luciferase promoter assays in two breast cancer cell lines identified two haplotypes (H11 and H12) stimulating significantly the expression of ZNF350 transcript compared with the common haplotype H8. The high expression of the H11 allele was associated with the variant c.-874A. Using MatInspector and Transcription Element Search softwares, in silico analyses predicted that the variant c.-874A created a binding site for the factors c-Myc and myogenin. This study represents the first characterization step of the ZNF350 promoter. Additional studies in larger cohorts and other populations will be needed to further evaluate whether common and/or rare ZNF350 promoter variants and haplotypes could be associated with a modest risk of breast cancer.

p53 controls hepatitis C virus non-structural protein 5A-mediated downregulation of GADD45α expression via the NF-κB and PI3K-Akt pathways

Growth arrest and DNA-damage-inducible gene 45-α (GADD45α) protein has been shown to be a tumour suppressor and is implicated in cell-cycle arrest and suppression of cell growth. The hepatitis C virus (HCV) non-structural 5A (NS5A) protein plays an important role in cell survival and is linked to the development of hepatocellular carcinoma (HCC). However, the role of HCV NS5A in the development of HCC remains to be clarified. This study sought to determine whether GADD45α mediates HCV NS5A-induced cellular survival and to elucidate the molecular mechanism of GADD45α expression regulated by HCV NS5A. It was found that HCV NS5A downregulated GADD45α expression at the transcriptional level by decreasing promoter activity, mRNA transcription and protein levels. Knockdown of p53 resulted in a similar decrease in GADD45α expression to that caused by HCV NS5A, whilst overexpression of p53 reversed the HCV NS5A-mediated downregulation of GADD45α. HCV NS5A repressed p53 expression, which was followed by a subsequent decrease in GADD45α expression. Further evidence was provided showing that HCV NS5A led to increases of phosphorylated nuclear factor-κB and Akt levels. Inhibition of these pathways using pharmacological inhibitors or specific small interfering RNAs rescued HCV NS5A-mediated downregulation of p53 and GADD45α. It was also found that HCV NS5A protein and depletion of GADD45α increased cell growth, whereas ectopic expression of GADD45α eliminated HCV NS5A-induced cell proliferation. These results indicated that HCV NS5A downregulates GADD45α expression and subsequently triggers cellular proliferation. These findings provide new insights suggesting that HCV NS5A could contribute to the occurrence of HCV-related HCC.

Drug resistance and its significance for treatment decisions in non-small-cell lung cancer

Non-small-cell lung cancer (nsclc) constitutes about 85% of all lung cancers. Approximately 50% of patients diagnosed with nsclc present with advanced disease (stage iii or iv) that is not amenable to curative treatment. The number of patients with stage iiib or iv disease who are alive at 1 year after diagnosis has increased from 10% in the untreated population in the early 1980s to 50% in patients with a good performance status receiving treatment today. However, those statistics remain dismal, and the two dominant reasons are the large number of patients diagnosed with advanced-stage disease and the observed primary or secondary resistance to current therapies. The present article addresses the question of drug resistance in lung cancer, focusing on subjects that are currently topical and under intense scrutiny.

[BRCA1: a new predictive genomic marker for chemotherapy and radiotherapy of non-small cell lung cancer]

Non-small cell lung cancer (NSCLC) is one of the most common malignant tumors worldwide. Chemotherapy and radiotherapy are the main methods in therapy of NSCLC. The identification and characterization of predictive markers of radio- and chemo-sensitivity will be beneficial with customized treatment of NSCLC patients. This article will review the evidence regarding breast cancer susceptibility gene 1 (BRCA1) as a new predictive marker for chemotherapy and radiotherapy of NSCLC.

Role of genotyping in non-small cell lung cancer treatment: current status

Non-small cell lung cancer (NSCLC) is a common malignant disease with an extremely poor prognosis. Chemotherapeutic treatment for advanced disease is currently based on histological subtyping, but recent discoveries of genetic alterations in subsets of NSCLC have already changed clinical practice with regard to Egfr mutations as predictive markers of response to gefitinib and erlotinib. This has also paved the way for the integration of molecular analyses into early phase clinical trials, as demonstrated by the clinical development of crizotinib, effective in lung cancer harbouring Alk rearrangements. Similarly, other subgroups of NSCLC carry potentially targetable molecular alterations and their study has the potential to change the diagnostic and therapeutic approach to lung cancer in the near future. In contrast to a wealth of knowledge surrounding genomic alterations in lung adenocarcinomas, fewer data are available concerning squamous cell lung cancer (SCC), although recent data demonstrate that genotyping can provide new therapeutic perspectives in SCC treatment. Moreover, the study of molecular predictive markers of response to chemotherapy aims to improve chemotherapeutic treatment, increasing efficacy and limiting toxicity.

Drug therapy for hereditary cancers

Tumors arising in patients with hereditary cancer syndromes may have distinct drug sensitivity as compared to their sporadic counterparts. Breast and ovarian neoplasms from BRCA1 or BRCA2 mutation carriers are characterized by deficient homologous recombination (HR) of DNA, that makes them particularly sensitive to platinum compounds or inhibitors of poly (ADP-ribose) polymerase (PARP). Outstandingly durable complete responses to high dose chemotherapy have been observed in several cases of BRCA-related metastatic breast cancer (BC). Multiple lines of evidence indicate that women with BRCA1-related BC may derive less benefit from taxane-based treatment than other categories of BC patients. There is virtually no reports directly assessing drug response in hereditary colorectal cancer (CRC) patients; studies involving non-selected (i.e., both sporadic and hereditary) CRC with high-level microsatellite instability (MSI-H) suggest therapeutic advantage of irinotecan. Celecoxib has been approved for the treatment of familial adenomatous polyposis (FAP). Hereditary medullary thyroid cancers (MTC) have been shown to be highly responsive to a multitargeted tyrosine kinase inhibitor vandetanib, which exerts specific activity towards mutated RET receptor. Given the rapidly improving accessibility of DNA analysis, it is foreseen that the potential predictive value of cancer-associated germ-line mutations will be increasingly considered in the future studies.

Germline BRCA mutation does not prevent response to taxane-based therapy for the treatment of castration-resistant prostate cancer

OBJECTIVE

• To investigate the relationship between BRCA mutation status and response to taxane-based chemotherapy, since BRCA mutation carriers with prostate cancer appear to have worse survival than non-carriers and docetaxel improves survival in patients with castration-resistant prostate cancer.

PATIENTS AND METHODS

• We determined BRCA mutation prevalence in 158 Ashkenazi Jewish (AJ) men with castration-resistant prostate cancer. Clinical data were collected as part of an institutional prostate cancer research database and through additional medical record review. • Clinical records and DNA samples were linked through a unique identifier, anonymizing the samples before genetic testing for the AJ BRCA1/2 founder mutations. • Response to taxane-based therapy was defined by the prostate-specific antigen nadir within 12 weeks of therapy.

RESULTS

• In all, 88 men received taxane-based treatment, seven of whom were BRCA carriers (three BRCA1, four BRCA2; 8%). Initial response to taxane was available for all seven BRCA carriers and for 69 non-carriers. • Overall, 71% (54/76) of patients responded to treatment, with no significant difference between carriers (57%) and non-carriers (72%) (absolute difference 15%; 95% confidence interval -23% to 53%; P= 0.4). • Among patients with an initial response, the median change in prostate-specific antigen was similar for BRCA carriers (-63%, interquartile range -71% to -57%) and non-carriers (-60%, interquartile range -78% to -35%) (P= 0.6). • At last follow-up, all seven BRCA carriers and 49 non-carriers had died from prostate cancer. One BRCA2 carrier treated with docetaxel plus platinum survived 37 months.

CONCLUSION

• In this small, hypothesis-generating study approximately half of BRCA carriers had a prostate-specific antigen response to taxane-based chemotherapy, suggesting that it is an active therapy in these individuals.

Tubulin, BRCA1, ERCC1, Abraxas, RAP80 mRNA expression, p53/p21 immunohistochemistry and clinical outcome in patients with advanced non small-cell lung cancer receiving first-line platinum-gemcitabine chemotherapy

BACKGROUND

The aim of this study was to assess the predictive value of tumor expression of nine genes on clinical outcome in patients with advanced NSCLC receiving platinum-gemcitabine chemotherapy.

METHODS

Quantitative PCR or immunohistochemistry were used to analyze the expression of β-tubuline IIA (TUBB2A), β-tubuline III (TUBB3), BRCA1, ERCC1, Abraxas (ABRX) and RAP80 in mRNA isolated from paraffin-embedded tumor biopsies of 45 NSCLC patients treated as part of a larger observational trial. All patients received first-line platinum-gemcitabine chemotherapy for stage IIIB or IV NSCLC.

RESULTS

Median progression-free survival (PFS) was 7 months, overall survival (OS) 12 months. A partial treatment response was found in 14 patients (33%). Patients with low ERCC1 or ABRX expression had a significantly better response to chemotherapy (R=-0.45, p<0.01 for ERCC1; R=-0.40, p=0.016 for ABRX). A significant correlation was found between the individual time for PFS and the expression of both ERCC1 (R=-0.36, p=0.015) and ABRX (R=-0.46, p=0.001). Patients with low ERCC1 expression had a longer OS as compared to patients with high ERCC1 expression (HR=0.26, log-rank p=0.02).

CONCLUSIONS

The study confirms tumor expression of ERCC1 as a predictor for clinical outcome in patients with advanced NSCLC receiving platinum-based chemotherapy, and found ABRX expression to be similarly predictive of clinical outcome. Prospective validation is warranted and - if confirmed - non platinum-containing chemotherapy should be explored as the preferred treatment in patients with high ERCC1 or ABRX expression and no activating mutations of EGFR.

Predicting response to chemotherapy with early-stage lung cancer

A recent meta-analysis of 11,107 patients with non-small cell lung cancer who had undergone surgical resection showed that the 5-year survival benefit of adjuvant chemotherapy was 4%, and that of adjuvant chemoradiotherapy was 5%. Two trials have shown a trend toward improved survival with adjuvant paclitaxel plus carboplatin. However, the benefit of adjuvant treatment remains suboptimal. We must distinguish between patients who will not relapse-and who can thus be spared adjuvant treatment-and those who will-for whom adjuvant treatment must be personalized. Several gene expression signatures, generally containing nonoverlapping genes, provide similar predictive information on clinical outcome, and a model combining several signatures did not perform better than did each of the signatures separately. The invasiveness gene signature, containing 186 genes, includes genes involved in the nuclear factor κB pathway, the RAS-mitogen-activated protein kinase pathway, and epigenetic control of gene expression. A 15-gene signature has identified JBR.10 patients who are more sensitive to adjuvant chemotherapy.

The DeltaNp63 proteins are key allies of BRCA1 in the prevention of basal-like breast cancer

Little is known about the origin of basal-like breast cancers, an aggressive disease that is highly similar to BRCA1-mutant breast cancers. p63 family proteins that are structurally related to the p53 suppressor protein are known to function in stem cell regulation and stratified epithelia development in multiple tissues, and p63 expression may be a marker of basal-like breast cancers. Here we report that ΔNp63 isoforms of p63 are transcriptional targets for positive regulation by BRCA1. Our analyses of breast cancer tissue microarrays and BRCA1-modulated breast cancer cell lines do not support earlier reports that p63 is a marker of basal-like or BRCA1 mutant cancers. Nevertheless, we found that BRCA1 interacts with the specific p63 isoform ΔNp63γ along with transcription factor isoforms AP-2α and AP-2γ. BRCA1 required ΔNp63γ and AP-2γ to localize to an intronic enhancer region within the p63 gene to upregulate transcription of the ΔNp63 isoforms. In mammary stem/progenitor cells, siRNA-mediated knockdown of ΔNp63 expression resulted in genomic instability, increased cell proliferation, loss of DNA damage checkpoint control, and impaired growth control. Together, our findings establish that transcriptional upregulation of ΔNp63 proteins is critical for BRCA1 suppressor function and that defects in BRCA1-ΔNp63 signaling are key events in the pathogenesis of basal-like breast cancer.

A microarray based expression profiling of paclitaxel and vincristine resistant MCF-7 cells

Resistance to the broad spectrum of chemotherapeutic agents in cancer cell lines and tumors has been called multiple drug resistance (MDR). In this study, the molecular mechanisms of resistance to two anticancer agents (paclitaxel and vincristine) in mammary carcinoma cell line MCF-7 were investigated. Drug resistant sublines to paclitaxel (MCF-7/Pac) and vincristine (MCF-7/Vinc) that were developed from sensitive MCF-7 cells (MCF-7/S) were used. cDNA microarray analysis was performed for the RNA samples of sensitive and resistant cells in duplicate experiments. GeneSpring GX 7.3.1 Software was used in data analysis. The results indicated that the upregulation of MDR1 gene is the dominating mechanism of the paclitaxel and vincristine drug resistance. Additionally the upregulation of the genes encoding the detoxifying enzymes (i.e. GSTP1) was observed. Significant downregulation of apoptotic genes (i.e. PDCD2/4/6/8) and upregulation of some cell cycle regulatory genes (CDKN2A, CCNA2 etc.) was seen which may be in close relation to MDR in breast cancer. Drug resistant cancer cells exhibit different gene expression patterns depending on drug treatment, and each drug resistance phenotype is probably genetically different. Further functional studies are needed to demonstrate the complete set of genes contributing to the drug resistance phenotype in breast cancer cells.

miR-182-mediated downregulation of BRCA1 impacts DNA repair and sensitivity to PARP inhibitors

Expression of BRCA1 is commonly decreased in sporadic breast tumors, and this correlates with poor prognosis of breast cancer patients. Here we show that BRCA1 transcripts are selectively enriched in the Argonaute/miR-182 complex and miR-182 downregulates BRCA1 expression. Antagonizing miR-182 enhances BRCA1 protein levels and protects them from IR-induced cell death, while overexpressing miR-182 reduces BRCA1 protein, impairs homologous recombination-mediated repair, and render cells hypersensitive to IR. The impaired DNA repair phenotype induced by miR-182 overexpression can be fully rescued by overexpressing miR-182-insensitive BRCA1. Consistent with a BRCA1-deficiency phenotype, miR-182-overexpressing breast tumor cells are hypersensitive to inhibitors of poly (ADP-ribose) polymerase 1 (PARP1). Conversely, antagonizing miR-182 enhances BRCA1 levels and induces resistance to PARP1 inhibitor. Finally, a clinical-grade PARP1 inhibitor impacts outgrowth of miR-182-expressing tumors in animal models. Together these results suggest that miR-182-mediated downregulation of BRCA1 impedes DNA repair and may impact breast cancer therapy.

Parameters for individualizing systemic therapy in non-small cell lung cancer

Rational drug design based on molecular targets is starting to revolutionize cancer care. To maximize its potential for patients, a concomitant leveraging of molecular knowledge for selection of patients to future and current therapeutic options is paramount. The terms "individualized", "personalized", or "precision therapy" are currently used to describe these efforts. Here, we summarize current knowledge for selection of systemic targeted and cytotoxic therapy for patients with non-small-cell lung cancer. Based on this knowledge, we present a potential decision algorithm to best select patients for currently available therapies, which include the treatment options single-agent erlotinib or gefitinib, the ALK inhibitor crizotinib, double agent gemcitabine and platinum, double agent platinum and pemetrexed, and as a default option a taxane combined with a non-platinum drug, for instance a vinca alkaloid. The addition of bevacizumab to double-agent chemotherapy is also discussed. Currently available data on predictive biomarkers are largely based on subgroup or companion biomarker analyses of patient cohorts or clinical trials. Current and emerging markers must be incorporated prospectively into the design of clinical trials that test novel and established agents to better understand their clinical utility and to refine selection parameters and marker interactions. Future development will lead to increasing complexity in clinical decision making with substantial anticipated benefits to patients including increased therapeutic efficacy, reduced toxicity, and better quality of life.

Analysis of the protein expression changes during taxol-induced apoptosis under translation inhibition conditions

Taxol is currently used in chemotherapeutic treatments of different types of cancers. In this article, we demonstrate that taxol induces apoptosis and translation down-regulation in human embryonic kidney (HEK293T) cells. Antibody arrays are a promising new tool for the analysis of protein levels changes in cells responding to different stimuli. Using this approach, we have identified changes in the expression of 38 proteins (20 down-regulated and 18 up-regulated), implicated in several cellular processes mainly in apoptosis, cell cycle and signal transduction pathways, and also cytoskeleton proteins. Among them, we have confirmed a considerable decrease in the expression of p14(ARF) and a significant increase in the levels of dystrophin and c-Myc. It is known that c-Myc mRNA has an internal ribosome entry segment (IRES) element in its 5'UTR that could regulate its expression under global protein synthesis inhibition conditions. We demonstrate that after taxol treatment, the c-Myc IRES activity is maintained meanwhile cap-dependent activity is inhibited. In addition, an increase in c-Myc mRNA was also observed after taxol treatment. We conclude that taxol-induced c-Myc expression is regulated at both transcriptional and translational levels, the last of them by a mechanism mediated by IRES.

Mycotoxin citrinin induced cell cycle G2/M arrest and numerical chromosomal aberration associated with disruption of microtubule formation in human cells

As a nephrotoxic mycotoxin, citrinin (CTN) contaminates various foodstuffs and animal feed commodities. In the present study, the effects of CTN on cell cycle arrest and microtubule formation were investigated by applying human embryonic kidney (HEK293) cells as a model. Exposure of HEK293 cells to CTN resulted in an arrest of cell cycle G2/M in a concentration-dependent increase. Administrating CTN elevated the expression levels of p53 and p21 proteins, yet attenuated the signals of phosphorylated cell division cycle 2 (cdc2). Furthermore, treating HEK293 with CTN increased both the value of mitotic index and the population of cells recognized by antibody mitotic protein monoclonal 2, suggesting that arrest of CTN-induced cell cycle occurred mainly during the mitotic phase. With the assistance of immunocytostaining of α-tubulin, CTN was found to disrupt the stable microtubule skeleton during the interphase of cell cycle and also interfere with the mitotic spindle integrity during mitosis. Additionally, for either in vivo or in vitro assays, CTN effectively inhibited tubulin polymerization in a concentration-dependent manner. When human peripheral blood mononuclear cells were exposed to CTN, the percentage of cells with numerical chromosome changes was increased by 4.3-fold over that of vehicle-treated group. Results of this study suggest that CTN-activated G2/M arrest primarily arises from the inhibition of tubulin polymerization and associated mitotic spindle formation. Additionally, disruption of microtubule organization by CTN also contributes to the induction of numerical chromosome aberration in human cells.