An integrative approach to identify YB-1-interacting proteins required for cisplatin resistance in MCF7 and MDA-MB-231 breast cancer cells

An uncertainty-based interpretable deep learning framework for predicting breast cancer outcome

BACKGROUND

Predicting outcome of breast cancer is important for selecting appropriate treatments and prolonging the survival periods of patients. Recently, different deep learning-based methods have been carefully designed for cancer outcome prediction. However, the application of these methods is still challenged by interpretability. In this study, we proposed a novel multitask deep neural network called UISNet to predict the outcome of breast cancer. The UISNet is able to interpret the importance of features for the prediction model via an uncertainty-based integrated gradients algorithm. UISNet improved the prediction by introducing prior biological pathway knowledge and utilizing patient heterogeneity information.

RESULTS

The model was tested in seven public datasets of breast cancer, and showed better performance (average C-index = 0.691) than the state-of-the-art methods (average C-index = 0.650, ranged from 0.619 to 0.677). Importantly, the UISNet identified 20 genes as associated with breast cancer, among which 11 have been proven to be associated with breast cancer by previous studies, and others are novel findings of this study.

CONCLUSIONS

Our proposed method is accurate and robust in predicting breast cancer outcomes, and it is an effective way to identify breast cancer-associated genes. The method codes are available at: https://github.com/chh171/UISNet .

Targeting YB-1 via entinostat enhances cisplatin sensitivity of pleural mesothelioma in vitro and in vivo

Pleural mesothelioma (PM) is characterized by poor prognosis and limited therapeutic options. Y-box-binding protein 1 (YB-1) was shown to drive growth and migration of PM cells. Here, we evaluated the effect of genetic and pharmacological targeting of YB-1 on PM growth and response to cisplatin and radiation treatment. YB-1 knockdown via siRNA resulted in reduced PM cell growth, which significantly correlated with wt BAP1 and mutant NF2 and P53 status. Entinostat inhibited YB-1 deacetylation and its efficacy correlated with YB-1 knockdown-induced growth inhibition in 20 PM cell lines. Tumor growth inhibition by siRNA as well as entinostat was confirmed in mouse xenotransplant models. Furthermore, both YBX1-targeting siRNA and entinostat enhanced sensitivity to cisplatin and radiation. In particular, entinostat showed strong synergistic interactions with cisplatin which was linked to significantly increased cellular platinum uptake in all investigated cell models. Importantly, in a mouse model, the combination of cisplatin and entinostat also resulted in stronger growth inhibition than each treatment alone. Our study highlights YB-1 as an attractive target in PM and demonstrates that targeting YB-1 via entinostat is a promising approach to enhance cisplatin and radiation sensitivity.

Genetic and Epigenetic Sexual Dimorphism of Brain Cells during Aging

In recent years, much of the attention paid to theoretical and applied biomedicine, as well as neurobiology, has been drawn to various aspects of sexual dimorphism due to the differences that male and female brain cells demonstrate during aging: (a) a dimorphic pattern of response to therapy for neurodegenerative disorders, (b) different age of onset and different degrees of the prevalence of such disorders, and (c) differences in their symptomatic manifestations in men and women. The purpose of this review is to outline the genetic and epigenetic differences in brain cells during aging in males and females. As a result, we hereby show that the presence of brain aging patterns in males and females is due to a complex of factors associated with the effects of sex chromosomes, which subsequently entails a change in signal cascades in somatic cells.

Chemotherapy Resistance: Role of Mitochondrial and Autophagic Components

Simple Summary

Chemotherapy resistance is a common occurrence during cancer treatment that cancer researchers are attempting to understand and overcome. Mitochondria are a crucial intracellular signaling core that are becoming important determinants of numerous aspects of cancer genesis and progression, such as metabolic reprogramming, metastatic capability, and chemotherapeutic resistance. Mitophagy, or selective autophagy of mitochondria, can influence both the efficacy of tumor chemotherapy and the degree of drug resistance. Regardless of the fact that mitochondria are well-known for coordinating ATP synthesis from cellular respiration in cellular bioenergetics, little is known its mitophagy regulation in chemoresistance. Recent advancements in mitochondrial research, mitophagy regulatory mechanisms, and their implications for our understanding of chemotherapy resistance are discussed in this review.

Abstract

Cancer chemotherapy resistance is one of the most critical obstacles in cancer therapy. One of the well-known mechanisms of chemotherapy resistance is the change in the mitochondrial death pathways which occur when cells are under stressful situations, such as chemotherapy. Mitophagy, or mitochondrial selective autophagy, is critical for cell quality control because it can efficiently break down, remove, and recycle defective or damaged mitochondria. As cancer cells use mitophagy to rapidly sweep away damaged mitochondria in order to mediate their own drug resistance, it influences the efficacy of tumor chemotherapy as well as the degree of drug resistance. Yet despite the importance of mitochondria and mitophagy in chemotherapy resistance, little is known about the precise mechanisms involved. As a consequence, identifying potential therapeutic targets by analyzing the signal pathways that govern mitophagy has become a vital research goal. In this paper, we review recent advances in mitochondrial research, mitophagy control mechanisms, and their implications for our understanding of chemotherapy resistance.

Targeting the Y-box Binding Protein-1 Axis to Overcome Radiochemotherapy Resistance in Solid Tumors

Multifunctional Y-box binding protein-1 (YB-1) is highly expressed in different human solid tumors and is involved in various cellular processes. DNA damage is the major mechanism by which radiochemotherapy (RCT) induces cell death. On induction of DNA damage, a multicomponent signal transduction network, known as the DNA damage response, is activated to induce cell cycle arrest and initiate DNA repair, which protects cells against damage. YB-1 regulates nearly all cancer hallmarks described to date by participating in DNA damage response, gene transcription, mRNA splicing, translation, and tumor stemness. YB-1 lacks kinase activity, and p90 ribosomal S6 kinase and AKT are the key kinases within the RAS/mitogen-activated protein kinase and phosphoinositide 3-kinase pathways that directly activate YB-1. Thus, the molecular targeting of ribosomal S6 kinase and AKT is thought to be the most effective strategy for blocking the cellular function of YB-1 in human solid tumors. In this review, after describing the prosurvival effect of YB-1 with a focus on DNA damage repair and cancer cell stemness, clinical evidence will be provided indicating an inverse correlation between YB-1 expression and the treatment outcome of solid tumors after RCT. In the interest of being concise, YB-1 signaling cascades will be briefly discussed and the current literature on YB-1 posttranslational modifications will be summarized. Finally, the current status of targeting the YB-1 axis, especially in combination with RCT, will be highlighted.

Treatment scheduling effects on the evolution of drug resistance in heterogeneous cancer cell populations

The effect of scheduling of targeted therapy combinations on drug resistance is underexplored in triple-negative breast cancer (TNBC). TNBC constitutes heterogeneous cancer cell populations the composition of which can change dynamically during treatment resulting in the selection of resistant clones with a fitness advantage. We evaluated crizotinib (ALK/MET inhibitor) and navitoclax (ABT-263; Bcl-2/Bcl-xL inhibitor) combinations in a large design consisting of 696 two-cycle sequential and concomitant treatment regimens with varying treatment dose, duration, and drug holiday length over a 26-day period in MDA-MB-231 TNBC cells and found that patterns of resistance depend on the schedule and sequence in which the drugs are given. Further, we tracked the clonal dynamics and mechanisms of resistance using DNA-integrated barcodes and single-cell RNA sequencing. Our study suggests that longer formats of treatment schedules in vitro screening assays are required to understand the effects of resistance and guide more realistically in vivo and clinical studies.

Knockdown of GTF2E2 inhibits the growth and progression of lung adenocarcinoma via RPS4X in vitro and in vivo

Background

Lung adenocarcinoma (LUAD) is one of the most common malignancies worldwide. However, the molecular mechanism of LUAD tumorigenesis and development remains unclear. The purpose of this study was to comprehensively illustrate the role of GTF2E2 in the growth and progression of LUAD.

Methods and materials

We obtained the mRNA expression data from The Cancer Genome Atlas, Gene Expression Omnibus database, and our institution. Systematic bioinformatical analyses were performed to investigate the expression and prognostic value of GTF2E2 in LUAD. The results were validated by immunohistochemistry and qPCR. The effect of knocking down GTF2E2 using two short hairpin RNAs was investigated by in vitro and in vivo assays. Subsequently, shotgun liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) analyses were applied to identified potential GTF2E2 interacting proteins, and the downstream molecular mechanisms of GTF2E2-signaling were further explored by a series of cellular functional assays.

Results

We found that GTF2E2 expression was significantly increased in LUAD tissue compared with adjacent normal tissue and was negatively associated with patients’ overall survival. Besides, we demonstrated that GTF2E2 knockdown inhibited LUAD cell proliferation, migration, invasion, and promote apoptosis in vitro, as well as attenuated tumor growth in vivo. Results from LC–MS/MS suggested that RPS4X might physically interact with GTF2E2 and mediated GTF2E2’s regulatory effect on LUAD development through the mTOR pathway.

Conclusion

Our findings indicate that GTF2E2 promotes LUAD development by activating RPS4X. Therefore, GTF2E2 might serve as a promising biomarker for the diagnosis and prognosis of LUAD patients, thus shedding light on the precise and personalized therapy for LUAD in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01878-z.

Linc00665 Can Predict the Response to Cisplatin-Paclitaxel Neoadjuvant Chemotherapy for Breast Cancer Patients

Objective

Linc00665 is a novel long non-coding RNA that can promote the progression of breast cancer, but its value in predicting the efficacy of neoadjuvant chemotherapy (NAC) for breast cancer has not been reported. We aim to analyze the correlation between Linc00665 expression and pathological complete response (pCR) in breast cancer patients.

Materials and Methods

The present study examined the predictive role of Linc00665 expression in pCR after NAC using both univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curve and area under curve (AUC) were utilized to evaluate the performance of Linc00665 in predicting pCR. The Kyoto Encyclopedia of Gene and Genome (KEGG) analysis and Gene Set Enrichment Analysis (GSEA) were also conducted to determine the biological processes where Linc00665 may participate in.

Results

The present study study totally enrolled 102 breast cancer patients. The univariate analysis showed that Linc00665 level, human epidermal growth factor receptor 2 (HER2) status and hormone receptor (HR) status were correlated with pCR. The multivariate analysis showed that Linc00665 expression was an independent predictor of pCR (OR = 0.351, 95% CI: 0.125–0.936, P = 0.040), especially in patients with HR-positive/HER2-negative subtype (OR = 0.272, 95% CI: 0.104–0.664, P = 0.005). The KEGG analysis indicated that Linc00665 may be involved in drug metabolism. The GSEA analysis revealed that Linc00665 is correlated to DNA damage repair.

Conclusion

Linc00665 may be a potential novel predictive biomarker for breast cancer in NAC, especially for HR-positive/HER2-negative patients.

Exploring six-coordinate germanium(IV)-diketonate complexes as anticancer agents

Cancer remains one of the leading causes of death worldwide and despite several attempts using chemotherapy to combat the deadly disease, toxic side effects and drug resistance temper efficacy [1]. Thus, drugs with potentially new mechanisms and lower toxicity to normal cells are needed. Metalloids such as arsenic compounds have been clinically beneficial in fighting cancer, but germanium is yet to gain such prominence [2,3]. We report the synthesis of four octahedral germanium(IV) complexes bearing acetylacetonato ligand, [GeIV(acac)3)]+, with different anions (3 - 6) using a streamlined synthetic approach. The compounds were structurally and electrochemically characterized using NMR, MS, X-ray crystallography, and cyclic voltammetry. The cyclic voltammogram of 3-5 revealed distinct irreversible peaks in the range of -0.9 to -1.9 V, corresponding to Ge(IV)/ Ge(II) or Ge(II)/Ge(0) couple in DMSO. We explored the anticancer activity of the complexes against a panel of cancer cell lines with IC50 values in the sub-micromolar range (9-15 μM). The compounds display ~3-fold selectivity in cancer cells over normal epithelial cells. In addition to the promising anticancer activity, the compounds display high complex stability in biological media, induces G1 arrest, reactive oxygen stress (ROS) accumulation, and mitochondria membrane depolarization in cancer cells. Furthermore, the compounds induce significant apoptosis.

Overexpression of the X-linked ribosomal protein S4 predicts poor prognosis in patients with intrahepatic cholangiocarcinoma

X-linked ribosomal protein S4 (RPS4X) has previously been reported to be associated with cisplatin resistance and clinical outcome in bladder and ovarian cancer. However, the value of RPS4X as a diagnostic and prognostic marker in intrahepatic cholangiocarcinoma (ICC) has not yet been investigated. The present study evaluated the expression pattern, and diagnostic and prognostic value of RPS4X in patients with ICC. Retrospective analysis was performed for a total of 201 patients with intrahepatic cholangiocarcinoma, and 8 patients with inflammation of the bile duct. Immunohistochemistry was performed using tissue microarrays to characterize the expression profile of RPS4X. Receiver operating characteristic (ROC) curves, the Kaplan-Meier estimator and Cox regression analysis were applied to evaluate the potential diagnostic and prognostic value of RPS4X in ICC. RPS4X was significantly upregulated in ICC tissues compared with the inflamed bile duct tissues. When differentiating ICC from normal controls, ROC analysis of RPS4X gave an area under the curve value of 0.9030 (sensitivity, 82.59%; specificity, 100%). RPS4X expression was significantly positively correlated with serum alkaline phosphatase levels. Survival analysis demonstrated that RPS4X expression levels were an independent prognostic factor for overall survival. Therefore, RPS4X expression levels may serve as a novel diagnostic and prognostic marker in ICC.

Bagging survival tree procedure for variable selection and prediction in the presence of nonsusceptible patients

Background

For clinical genomic studies with high-dimensional datasets, tree-based ensemble methods offer a powerful solution for variable selection and prediction taking into account the complex interrelationships between explanatory variables. One of the key component of the tree-building process is the splitting criterion. For survival data, the classical splitting criterion is the Logrank statistic. However, the presence of a fraction of nonsusceptible patients in the studied population advocates for considering a criterion tailored to this peculiar situation.

Results

We propose a bagging survival tree procedure for variable selection and prediction where the survival tree-building process relies on a splitting criterion that explicitly focuses on time-to-event survival distribution among susceptible patients.

A simulation study shows that our method achieves good performance for the variable selection and prediction. Different criteria for evaluating the importance of the explanatory variables and the prediction performance are reported. Our procedure is illustrated on a genomic dataset with gene expression measurements from early breast cancer patients.

Conclusions

In the presence of nonsusceptible patients among the studied population, our procedure represents an efficient way to select event-related explanatory covariates with potential higher-order interaction and identify homogeneous groups of susceptible patients.

Low level of the X-linked ribosomal protein S4 in human urothelial carcinomas is associated with a poor prognosis

AIM

We determined whether the Y-box binding protein-1 (YB-1) and its binding partner, the X-linked ribosomal protein S4 (RPS4X), are associated with clinical outcome in bladder cancer.

MATERIALS & METHODS

A population of 167 patients with muscle-invasive bladder tumor without evidence of metastasis at time of cystectomy was analyzed retrospectively. YB-1 and RPS4X expressions were evaluated immunohistochemically in tumors and analyzed for association with clinical variables and survival.

RESULTS

Kaplan-Meier and multivariate Cox regression analyses indicated that low expression of RPS4X was associated with a higher risk of death or disease recurrence. In contrast, YB-1 was not significantly associated with either recurrence-free or overall survival.

CONCLUSION

Low RPS4X expression is associated with poor disease-specific and recurrence-free survival in bladder cancer.

Noncoding RNAs that associate with YB-1 alter proliferation in prostate cancer cells

The highly conserved, multifunctional YB-1 is a powerful breast cancer prognostic indicator. We report on a pervasive role for YB-1 in which it associates with thousands of nonpolyadenylated short RNAs (shyRNAs) that are further processed into small RNAs (smyRNAs). Many of these RNAs have previously been identified as functional noncoding RNAs (http://www.johnlab.org/YB1). We identified a novel, abundant, 3'-modified short RNA antisense to Dicer1 (Shad1) that colocalizes with YB-1 to P-bodies and stress granules. The expression of Shad1 was shown to correlate with that of YB-1 and whose inhibition leads to an increase in cell proliferation. Additionally, Shad1 influences the expression of additional prognostic markers of cancer progression such as DLX2 and IGFBP2. We propose that the examination of these noncoding RNAs could lead to better understanding of prostate cancer progression.

Expression of a novel peptide derived from PCNA damages DNA and reverses cisplatin resistance

BACKGROUND

An 8 amino acid peptide sequence derived from proliferating cell nuclear antigen (PCNA) has been shown to effectively kill several breast cancer and neuroblastoma cell lines when added exogenously to cell cultures.

METHODS

In this study, the expression of the 8 amino acid peptide sequence (caPeptide) was placed under control of a tetracycline responsive promoter in MDA-MB-231 cells.

RESULTS

Endogenous expression of the peptide resulted in an increase in genomic DNA damage. CaPeptide induction combined with treatment of sublethal doses of cisplatin resulted in a marked increase in death of the cisplatin-resistant MDA-MB-231 cell line. CaPeptide was found to interact with POLD3, one of the subunits of DNA polymerase delta necessary for binding to PCNA.

CONCLUSION

These results suggest an important line of inquiry into the possible role that caPeptide might play in the reversal of cisplatin resistance in breast and other cancers. This is of particular interest in those cancers where cisplatin is the first line of chemotherapy and where the acquisition of resistance is a common malady.

Systems biology of cisplatin resistance: past, present and future

The platinum derivative cis-diamminedichloroplatinum(II), best known as cisplatin, is currently employed for the clinical management of patients affected by testicular, ovarian, head and neck, colorectal, bladder and lung cancers. For a long time, the antineoplastic effects of cisplatin have been fully ascribed to its ability to generate unrepairable DNA lesions, hence inducing either a permanent proliferative arrest known as cellular senescence or the mitochondrial pathway of apoptosis. Accumulating evidence now suggests that the cytostatic and cytotoxic activity of cisplatin involves both a nuclear and a cytoplasmic component. Despite the unresolved issues regarding its mechanism of action, the administration of cisplatin is generally associated with high rates of clinical responses. However, in the vast majority of cases, malignant cells exposed to cisplatin activate a multipronged adaptive response that renders them less susceptible to the antiproliferative and cytotoxic effects of the drug, and eventually resume proliferation. Thus, a large fraction of cisplatin-treated patients is destined to experience therapeutic failure and tumor recurrence. Throughout the last four decades great efforts have been devoted to the characterization of the molecular mechanisms whereby neoplastic cells progressively lose their sensitivity to cisplatin. The advent of high-content and high-throughput screening technologies has accelerated the discovery of cell-intrinsic and cell-extrinsic pathways that may be targeted to prevent or reverse cisplatin resistance in cancer patients. Still, the multifactorial and redundant nature of this phenomenon poses a significant barrier against the identification of effective chemosensitization strategies. Here, we discuss recent systems biology studies aimed at deconvoluting the complex circuitries that underpin cisplatin resistance, and how their findings might drive the development of rational approaches to tackle this clinically relevant problem.

Low expression of the X-linked ribosomal protein S4 in human serous epithelial ovarian cancer is associated with a poor prognosis

BACKGROUND

The X-linked ribosomal protein S4 (RPS4X), which is involved in cellular translation and proliferation, has previously been identified as a partner of the overexpressed multifunctional protein YB-1 in several breast cancer cells. Depletion of RPS4X results in consistent resistance to cisplatin in such cell lines.

METHODS

As platinum-based chemotherapy is a standard first line therapy used to treat patients with ovarian cancer, we evaluated the prognostic value of RPS4X and YB-1 at the protein level in specimen from 192 high-grade serous epithelial ovarian cancer patients.

RESULTS

Immunohistochemistry studies indicated that high expression of RPS4X was associated with a lower risk of death and later disease progression (HR = 0.713, P = 0.001 and HR = 0.761, P = 0.001, respectively) as compared to low expression of RPS4X. In contrast, YB-1 was not significantly associated with either recurrence or survival time in this cohort. Finally, the depletion of RPS4X with different siRNAs in two different ovarian cancer cell lines reduced their proliferative growth rate but more importantly increased their resistance to cisplatin.

CONCLUSION

Altogether, these results suggest that the levels of RPS4X could be a good indicator for resistance to platinum-based therapy and a prognostic marker for ovarian cancer. Our study also showed that RPS4X is an independent prognostic factor in patients with serous epithelial ovarian cancer.

Phospho-ΔNp63α/microRNA feedback regulation in squamous carcinoma cells upon cisplatin exposure

Our previous reports showed that the cisplatin exposure induced the ATM-dependent phosphorylation of ΔNp63a, which is subsequently involved in transcriptional regulation of gene promoters encoding mRNAs and microRNAs in squamous cell carcinoma (SCC) cells upon cisplatin-induced cell death. We showed that phosphorylated (p)-ΔNp63a plays a role in upregulation of pro-apoptotic proteins, while non-p-ΔNp63a is implicated in pro-survival signaling. In contrast to non-p-ΔNp63a, p-ΔNp63a modulated expression of specific microRNAs in SCC cells exposed to cisplatin. These microRNAs were shown to attenuate the expression of several proteins involved in cell death/survival, suggesting the critical role for p-ΔNp63a in regulation of tumor cell resistance to cisplatin. Here, we studied the function of ΔNp63a in transcriptional activation and repression of the specific microRNA promoters whose expression is affected by cisplatin treatment of SCC cells. We quantitatively studied chromatin-associated proteins bound to tumor protein (TP) p63-responsive element, we found that p-ΔNp63a along with certain transcription coactivators (e.g., CARM1, KAT2B, TFAP2A, etc.) necessary to induce gene promoters for microRNAs (630 and 885-3p) or with transcription corepressors (e.g., EZH2, CTBP1, HDACs, etc.) needed to repress promoters for microRNAs (181a-5p, 374a-5p and 519a-3p) in SCC cells exposed to cisplatin.

NONO and RALY proteins are required for YB-1 oxaliplatin induced resistance in colon adenocarcinoma cell lines

Background

YB-1 is a multifunctional protein that affects transcription, splicing, and translation. Overexpression of YB-1 in breast cancers causes cisplatin resistance. Recent data have shown that YB-1 is also overexpress in colorectal cancer. In this study, we tested the hypothesis that YB-1 also confers oxaliplatin resistance in colorectal adenocarcinomas.

Results

We show for the first time that transfection of YB-1 cDNA confers oxaliplatin resistance in two colorectal cancer cell lines (SW480 and HT29 cell lines). Furthermore, we identified by mass spectrometry analyses important YB-1 interactors required for such oxaliplatin resistance in these colorectal cancer cell lines. A tagged YB-1 construct was used to identify proteins interacting directly to YB-1 in such cells. We then focused on proteins that are potentially involved in colorectal cancer progression based on the Oncomine microarray database. Genes encoding for these YB-1 interactors were also examined in the public NCBI comparative genomic hybridization database to determine whether these genes are localized to regions of chromosomes rearranged in colorectal cancer tissues. From these analyses, we obtained a list of proteins interacting with YB-1 and potentially involved in oxaliplatin resistance. Oxaliplatin dose response curves of SW480 and HT29 colorectal cancer cell lines transfected with several siRNAs corresponding to each of these YB-1 interactors were obtained to identify proteins significantly affecting oxaliplatin sensitivity upon gene silencing. Only the depletion of either NONO or RALY sensitized both colorectal cancer cell lines to oxaliplatin. Furthermore, depletion of NONO or RALY sensitized otherwise oxaliplatin resistant overexpressing YB-1 SW480 or HT29 cells.

Conclusion

These results suggest knocking down NONO or RALY significant counteracts oxaliplatin resistance in colorectal cancers overexpressing the YB-1 protein.

Cisplatin@US-tube carbon nanocapsules for enhanced chemotherapeutic delivery

The use of chemotherapeutic drugs in cancer therapy is often limited by problems with administration such as insolubility, inefficient biodistribution, lack of selectivity, and inability of the drug to cross cellular barriers. To overcome these limitations, various types of drug delivery systems have been explored, and recently, carbon nanotube (CNT) materials have also garnered attention in the area of drug delivery. In this study, we describe the preparation, characterization, and in vitro testing of a new ultra-short single-walled carbon nanotube (US-tube)-based drug delivery system for the treatment of cancer. In particular, the encapsulation of cisplatin (CDDP), a widely-used anticancer drug, within US-tubes has been achieved, and the resulting CDDP@US-tube material characterized by high-resolution transmission electron microscopy (HR-TEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and inductively-coupled optical emission spectrometry (ICP-OES). Dialysis studies performed in phosphate-buffered saline (PBS) at 37 °C have demonstrated that CDDP release from CDDP@US-tubes can be controlled (retarded) by wrapping the CDDP@US-tubes with Pluronic-F108 surfactant. Finally, the anticancer activity of pluronic-wrapped CDDP@US-tubes has been evaluated against two different breast cancer cell lines, MCF-7 and MDA-MB-231, and found to exhibit enhanced cytotoxicity over free CDDP after 24 h. These studies have laid the foundation for developing US-tube-based delivery of chemotherapeutics, with drug release mainly limited to within cancer cells only.

Forced Expression of ZNF143 Restrains Cancer Cell Growth

We previously reported that the transcription factor Zinc Finger Protein 143 (ZNF143) regulates the expression of genes associated with cell cycle and cell division, and that downregulation of ZNF143 induces cell cycle arrest at G2/M. To assess the function of ZNF143 expression in the cell cycle, we established two cells with forced expression of ZNF143 derived from PC3 prostate cancer cell lines. These cell lines overexpress genes associated with cell cycle and cell division, such as polo-like kinase 1 (PLK1), aurora kinase B (AURKB) and some minichromosome maintenance complex components (MCM). However, the doubling time of cells with forced expression of ZNF143 was approximately twice as long as its control counterpart cell line. Analysis following serum starvation and re-seeding showed that PC3 cells were synchronized at G1 in the cell cycle. Also, ZNF143 expression fluctuated, and was at its lowest level in G2/M. However, PC3 cells with forced expression of ZNF143 synchronized at G2/M, and showed lack of cell cycle-dependent fluctuation of nuclear expression of MCM proteins. Furthermore, G2/M population of both cisplatin-resistant PCDP6 cells over-expressing ZNF143 (derived from PC3 cells) and cells with forced expression of ZNF143 was significantly higher than that of each counterpart, and the doubling time of PCDP6 cells is about 2.5 times longer than that of PC3 cells. These data suggested that fluctuations in ZNF143 expression are required both for gene expression associated with cell cycle and for cell division.