Abstract P4-07-13: High microRNA-621 level predicts a better response to neoadjuvant chemotherapy in breast cancer patients

Purpose: Weekly paclitaxel plus carboplatin (PCb) regimen is an effective neoadjuvant chemotherapy for breast cancer. However, some patients respond to this regimen poorly and suffer from side effects. In this study, we aimed to define the microRNA (miRNA) biomarker for predicting sensitivity to PCb chemotherapy in breast cancer patients, and to explore the potential molecular mechanisms.

Experimental Design: 81 patients with stages II and III breast cancer, who received four cycles of weekly PCb regimen preoperative chemotherapy, were included. Gene expression profiles from 31 patients was used as training set to determine differentially expressed genes (DEGs) and to predict miRNAs that may be associated with chemotherapeutic sensitivity. The other 50 patients were analyzed as validation set to test the accuracy of DEG identification and miRNAs prediction by quantitative real-time PCR. In parallel, in vitro and in vivo analyses were carried out to determine the potential mechanisms of miRNA-dependent drug sensitivity.

Results: Gene profiling analyses in the training set revealed significant correlation between high expression level of miR-345 and miR-621 and pathologic complete response (pCR) in breast cancer patients. We further validated that the expression level of miR-621 was significantly higher in tumor tissues of pCR patients than that in non-pCR patients (P = 0.01). In breast cancer cell lines, ectopic overexpression of miR-621 promoted apoptosis and increased chemosensitivity to paclitaxel and carboplatin both in vitro and in vivo. The potential miR-621-target genes were determined by TargetScan and miRNA CLIP-seq database, which were further confirmed as DEGs reversely-correlated to miR-621 in breast cancer patient samples. Among those, FBXO11 was verified as one of the direct targets of miR-621 in breast cancer cells, whose expression level negatively associated with chemosensitivity in breast cancer patients. The molecular mechanisms by which miR-621/FBXO11 axis regulates chemosensitivity may involve regulation of p53 transcriptional activity and epithelial-mesenchymal transition (EMT) in breast cancer cells.

Conclusions: Our study revealed a strong correlation between miR-621 expression and chemosensitivity in breast cancers. High level of miR-621 predicts sensitivity to PCb regimen neoadjuvant chemotherapy in breast cancer patients who tend to achieve pCR. The increased chemosensitivity may be mediated by down-regulation of FBXO11 gene, which leads to enhanced p53 transactivity and reduced EMT in breast cancer cells. Therefore, miR-621 may be used as predictive biomarker and the potential therapeutic target in breast cancer treatment.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-07-13.

Abstract P5-04-11: CDK11p58 inhibits estrogen receptor a positive breast cancer invasion via integrinb3 through repressing ERa signaling

Background: The sex steroid estrogen plays a major role in the development and progression of breast cancer. Estrogen promotes breast cancer proliferation through a number of established pathways. CDK11p58, a Ser/Thr kinase which belongs to Cell Division Cycle 2-like 1 (CDC2L1) subfamily, is associated with cell cycle progression, tumorigenesis and apoptotic signaling. In the previous study, we found that CDK11p58 interacted with estrogen receptor a (ERa) in breast tumor cells and repressed ERa transcriptional activity through promoting its ubiquitin/proteasome-mediated degradation. Here we sought to investigate the critical role of CDK11p58 in the carcinogenisis of breast cancer.

Methods and results: We measured the expression of CDK11p58 in 132 pairs of breast cancer tissues and adjacent tissues by IHC and qPCR. The mRNA and protein level of CDK11p58 were significant higher in breast cancer tissues than those in normal breast tissues. Interestingly, low expression of CDK11 was associated with lymph nodes metastasis in patients (P<0.05). Using the ERa + cell lines ZR-75-30 and T47D, we found CDK11p58 could repress the migration and invasion of ERa positive breast cancer cells. We further demonstrated that mRNA of integrinb3 were dramatically repressed by CDK11p58 by the TaqMan® Metastasis Gene Expression Assays. The effect was CDK11p58 kinase activity dependent. Expression of integrinβ3 was highly related with ERa signaling. While overexpression ERa stimulates integrinβ3 expression, knockdown of ERa attenuates integrinβ3 expression. By the Dual-luciferase array and CHIP assay, we found estrogen response elements (ERE) indeed existed in integrinβ3 promoter. ERa bound to the ERE on the integrinβ3 promoter and increased its transcription.

Conclusions: Our findings provide mechanistic insights into how CDK11p58 regulated the expression of integrinβ3 to inhibit the cell invasion though repressing the signaling of ERa in a kinase activity dependent way. These data indicate that CDK11p58 is an antimetastasis gene product in breast cancer and regulation of integrinβ3 by CDK11p58 through ERa could be part of a signaling pathway that determines and explains breast cancer invasion and metastasis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-04-11.

Note: Characteristic beam parameter for the line electron gun

We have optimized the beam parameters of line source electron gun using Stanford Linear Accelerator Centre electron beam trajectory program (EGUN), utilizing electrostatic focusing only. We measured minimum beam diameter as 0.5 mm that corresponds to power density of 68.9 kW/cm(2) at 13.5 mm in the post-anode region which is more than two-fold (33 kW/cm(2)), of the previously reported results. The gun was operated for the validation of the theoretical results and found in good agreement. The gun is now without any magnetic and electrostatic focusing thus much simpler and more powerful.

Carbon-based dots co-doped with nitrogen and sulfur for high quantum yield and excitation-independent emission

Helpful elements: A facile bottom-up method using citric acid and L-cysteine as a precursor has been developed to prepare graphene quantum dots (GQDs) co-doped with nitrogen and sulfur. A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission. FLQY = fluorescence quantum yield.

Preparation of graphite-like carbon nitride nanoflake film with strong fluorescent and electrochemiluminescent activity

The preparation, characterization, fluorescence (FL) and electrochemiluminescence (ECL) of graphite-like carbon nitride nanoflake particles (g-C(3)N(4) NFPs) and nanoflake films (g-C(3)N(4) NFFs) have been reported. Highly water-dispersible g-C(3)N(4) NFPs with a height of ~5 to 35 nm and a lateral dimension of ~40 to 220 nm have been extracted from bulk g-C(3)N(4) materials by chemical oxidation. New, stable and defined g-C(3)N(4) NFFs can be easily obtained by drying NFPs on certain hydrophilic substrates such as glass or electrode surfaces. Both g-C(3)N(4) NFPs and g-C(3)N(4) NFFs have good FL activities, i.e. they can give strong blue light (435 nm) emission under UV light (365 nm) excitation. The as-prepared g-C(3)N(4) NFFs on a glassy carbon electrode exhibit strong non-surface state ECL activity in the presence of reductive-oxidative coreactants, including dissolved oxygen (O(2)), hydrogen peroxide (H(2)O(2)) and peroxydisulfate (S(2)O(8)(2-)) and give rise to blue light emission (435 nm), which is the same as the wavelength of FL. The non-surface state ECL mechanisms of the g-C(3)N(4) NFF-coreactant systems have been studied and discussed in detail.

Asymmetric dimethylarginine and carotid atherosclerosis in Type 2 diabetes mellitus

BACKGROUND

Circulating asymmetric dimethylarginine (ADMA) concentration is elevated in patients with Type 2 diabetes mellitus (T2DM).

AIM

To assess the relationship between plasma ADMA concentration and carotid atherosclerosis in patients with T2DM.

SUBJECTS AND METHODS

A total of 72 newly diagnosed and untreated T2DM individuals and 72 healthy controls were studied. Carotid atherosclerosis was determined by ultrasonographically evaluated intima- media thickness (IMT) and plaque score. Plasma concentration of ADMA was measured by high-performance liquid chromatography.

RESULTS

Plasma ADMA, mean IMT, and plaque score were higher in diabetic patients compared with controls. Univariate and multivariate analyses demonstrated an independent association between ADMA and mean IMT in diabetic patients. On a multiple logistic regression analysis, ADMA was the sole predictor of carotid plaque formation (plaque score ≥1.1) (odds ratio 2.43, 95% confidence interval 1.19 to 4.94, p<0.05).

CONCLUSION

Our results suggest that increased levels of ADMA might be involved in the development of carotid atherosclerosis in T2DM.

Cordycepin as a sensitizer to tumour necrosis factor (TNF)-α-induced apoptosis through eukaryotic translation initiation factor 2α (eIF2α)- and mammalian target of rapamycin complex 1 (mTORC1)-mediated inhibition of nuclear factor (NF)-κB

Cordycepin (3'-deoxyadenosine) is one of the major bioactive substances produced by Cordyceps militaris, a traditional medicinal mushroom. Cordycepin possesses several biological activities, including both pro-apoptotic and anti-apoptotic properties. In the present report, we investigated an effect of cordycepin on the survival of cells exposed to tumour necrosis factor (TNF)-α. We found that subtoxic doses of cordycepin increased susceptibility of cells to TNF-α-induced apoptosis. It was associated with suppression of nuclear factor-κB (NF-κB), a major prosurvival component involved in TNF-α signalling. The adenosine transporter and A₃ adenosine receptor, but not A₁ and A₂ adenosine receptors, mediated both anti-NF-κB and pro-apoptotic effects. We found that cordycepin had the potential to phosphorylate eukaryotic translation initiation factor 2α (eIF2α) and that activation of eIF2α mimicked the suppressive effect of cordycepin on the NF-κB pathway. Furthermore, activation of eIF2α sensitized cells to TNF-α-induced apoptosis. To identify molecular events downstream of eIF2α, the role of mammalian target of rapamycin complex 1 (mTORC1) was examined. Selective activation of ₃eIF2α, as well as treatment with cordycepin, caused phosphorylation of mTORC1. Rapamycin, an inhibitor of mTORC1, significantly reversed the suppressive effects of eIF2α on NF-κB. These results suggest that cordycepin sensitizes cells to TNF-α-induced apoptosis, at least in part, via induction of the eIF2α-mTORC1 pathway and consequent suppression of NF-κB.