Identification of novel biomarkers associated with poor patient outcomes in invasive breast carcinoma

Moringin, an isothiocyanate modulates multiple cellular signalling molecules in breast cancer cells

Prohibitin (PHB) is a pleiotropic molecule with a variety of known functions and subcellular locations. PHB's function in breast cancer is poorly understood. Herein, we report that PHB is expressed in cancer types of diverse origin including breast cancer. The cancer patients with changes in PHB were reported to have significantly reduced 'overall survival' in comparison to the cases without alterations in PHB. The expression of PHB was increased by H2O2 and also by Moringin (MG), which is an isothiocyanate derived from the seeds of Moringa oleifera. MG interacted with PHB, DRP1, and SLP2 and inhibited the growth of MCF-7 and MDAMB-231 cells. The isothiocyanate triggered apoptosis in breast cancer cells as revealed by AO/PI assay, phosphatidylserine externalization, cell cycle analysis and DAPI staining. MG induced proapoptotic proteins expression such as cytochrome c, p53, and cleaved caspase-7. Further, cell survival proteins such as survivin, Bcl-2, and Bcl-xL were suppressed. A depolarization of membrane potential suggested that the apoptosis was triggered through mitochondria. The isothiocyanate suppressed the cancer cell migration and interacted with NF-κB subunits. MG suppressed p65 nuclear translocation induced by TNF-α. The reactive oxygen species generation was also induced by the isothiocyanate in breast cancer cells. MG also modulated the expression of lncRNAs. Collectively, the functions of PHB in breast cancer growth is evident from this study. The activities of MG against breast cancer might result from its ability to modulate multiple cancer-related targets.

UBXN1 promotes liver tumorigenesis by regulating mitochondrial homeostasis

BACKGROUND

The maintenance of mitochondrial homeostasis is critical for tumor initiation and malignant progression because it increases tumor cell survival and growth. The molecular events controlling mitochondrial integrity that facilitate the development of hepatocellular carcinoma (HCC) remain unclear. Here, we report that UBX domain-containing protein 1 (UBXN1) hyperactivation is essential for mitochondrial homeostasis and liver tumorigenesis.

METHODS

Oncogene-induced mouse liver tumor models were generated with the Sleeping Beauty (SB) transposon delivery system. Assessment of HCC cell growth in vivo and in vitro, including tumour formation, colony formation, TUNEL and FACS assays, was conducted to determine the effects of UBXN1 on HCC cells, as well as the involvement of the UBXN1-prohibitin (PHB) interaction in mitochondrial function. Coimmunoprecipitation (Co-IP) was used to assess the interaction between UBXN1 and PHB. Liver hepatocellular carcinoma (LIHC) datasets and HCC patient samples were used to assess the expression of UBXN1.

RESULTS

UBXN1 expression is commonly upregulated in human HCCs and mouse liver tumors and is associated with poor overall survival in HCC patients. UBXN1 facilitates the growth of human HCC cells and promotes mouse liver tumorigenesis driven by the NRas/c-Myc or c-Myc/shp53 combination. UBXN1 interacts with the inner mitochondrial membrane protein PHB and sustains PHB expression. UBXN1 inhibition triggers mitochondrial damage and liver tumor cell apoptosis.

CONCLUSIONS

UBXN1 interacts with PHB and promotes mitochondrial homeostasis during liver tumorigenesis.

Integration of scHi-C and scRNA-seq data defines distinct 3D-regulated and biological-context dependent cell subpopulations

An integration of 3D chromatin structure and gene expression at single-cell resolution has yet been demonstrated. Here, we develop a computational method, a multiomic data integration (MUDI) algorithm, which integrates scHi-C and scRNA-seq data to precisely define the 3D-regulated and biological-context dependent cell subpopulations or topologically integrated subpopulations (TISPs). We demonstrate its algorithmic utility on the publicly available and newly generated scHi-C and scRNA-seq data. We then test and apply MUDI in a breast cancer cell model system to demonstrate its biological-context dependent utility. We found the newly defined topologically conserved associating domain (CAD) is the characteristic single-cell 3D chromatin structure and better characterizes chromatin domains in single-cell resolution. We further identify 20 TISPs uniquely characterizing 3D-regulated breast cancer cellular states. We reveal two of TISPs are remarkably resemble to high cycling breast cancer persister cells and chromatin modifying enzymes might be functional regulators to drive the alteration of the 3D chromatin structures. Our comprehensive integration of scHi-C and scRNA-seq data in cancer cells at single-cell resolution provides mechanistic insights into 3D-regulated heterogeneity of developing drug-tolerant cancer cells.

Androgens Modulate Bcl-2 Agonist of Cell Death (BAD) Expression and Function in Breast Cancer Cells

Androgen receptor (AR) expression in estrogen receptor-positive (ER+) breast cancer (BC) correlates with lower tumor grade and a better clinical outcome. Additionally, in normal mammary epithelium or ER+ BC preclinical models, androgens counteract basal/ER-dependent proliferation. Here, we report an additional mechanism, underlining the protective role exerted by AR. Specifically, the activation of intracellular AR upregulates the Bcl-2-family protein BAD, and TCGA database analyses show that in ER+ BC, BAD expression is associated with better disease-free survival. Ligand-activated AR influences its own and BAD cellular compartmentalization by enhancing levels in the nucleus, as well as in mitochondrial fractions. In both compartments, BAD exerts unconventional functions. In the nucleus, BAD and AR physically interact and, upon androgen stimulation, are recruited at the AP-1 and ARE sites within the cyclin D1 promoter region, contributing to explaining the anti-proliferative effect of androgens in BC cells. Androgens cause an enrichment in BAD and AR content in the mitochondria, correlated with a decrease in mitochondrial function. Thus, we have defined a novel mechanism by which androgens modulate BAD expression, its mitochondria localization, and nuclear content to force its ability to act as a cell cycle inhibitor, strengthening the protective role of androgen signaling in estrogen-responsive BCs.

GTSE1 is possibly involved in the DNA damage repair and cisplatin resistance in osteosarcoma

Background

G2 and S phase-expressed-1 (GTSE1) negatively regulates the tumor-suppressive protein p53 and is potentially correlated with chemoresistance of cancer cells. This study aims to explore the effect of GTSE1 on the DNA damage repair and cisplatin (CDDP) resistance in osteosarcoma (OS).

Materials and methods

Expression of GTSE1 in OS was predicted in bioinformatics system GEPIA and then validated in clinically obtained tissues and acquired cell lines using RT-qPCR, immunohistochemical staining, and western blot assays. Gain- and loss-of-function studies of GTSE1 were performed in MG-63 and 143B cells to examine its function in cell cycle progression, DNA replication, and CDDP resistance. Stably transfected MG-63 cells were administrated into mice, followed by CDDP treatment to detect the role of GTSE1 in CDDP resistance in vivo.

Results

GTSE1 was highly expressed in patients with OS and correlated with poor survival according to the bioinformatics predictions. Elevated GTSE1 expression was detected in OS tissues and cell lines. GTSE1 silencing reduced S/G2 transition and DNA replication, and it increased the CDDP sensitivity and decreased the expression of DNA repair-related biomarkers in MG-63 cells. GTSE1 overexpression in 143B cells led to inverse trends. In vivo, downregulation of GTSE1 strengthened the treating effect of CDDP and significantly repressed growth of xenograft tumors in nude mice. However, overexpression of GTSE1 blocked the anti-tumor effect of CDDP.

Conclusion

This study demonstrates that GTSE1 is possibly involved in the DNA damage repair and cisplatin resistance in OS.

Isosteroidal alkaloids from Fritillaria hupehensis Hsiao et K.C.Hsia: Synthesis and biological evaluation of alkaloid derivatives as potential cytotoxic agents

One new cevanine isosteroidal alkaloid named 5,6-anhydrohupehenine (1), together with five known alkaloids (2-6) were isolated from Fritillaria hupehensis Hsiao et K.C.Hsia, among which 5,6-anhydrohupehenine (1) exhibited strong inhibitory activity against HepG2 (IC₅₀ = 12.21 μM) and MCF-7 (IC₅₀ = 22.05 μM) cancer cells. Therefore, a total of 33 5,6-anhydrohupehenine derivatives (9a-9s, 10a-10f, 11a-11b, and 12a-12f) were synthesized and evaluated for their cytotoxic activity. The cytotoxicity evaluation of all 5,6-anhydrohupehenine derivatives against HepG2 and MCF-7 human cancer cells revealed that 9s displayed best activity against HepG2 cells with IC₅₀ at 1.27 μM. Further biological evaluations on 9s showed that it inhibited the proliferation of HepG2 cells and induced apoptosis of the HepG2 cells by activating cleaved caspase-3. Moreover, 9s exhibited strong antimetastatic potential. These results suggest that 5,6-anhydrohupehenine is a promising compound to be designed as novel cytotoxic agents.

Wip1 controls the translocation of the chromosomal passenger complex to the central spindle for faithful mitotic exit

Dramatic cellular reorganization in mitosis critically depends on the timely and temporal phosphorylation of a broad range of proteins, which is mediated by the activation of the mitotic kinases and repression of counteracting phosphatases. The mitosis-to-interphase transition, which is termed mitotic exit, involves the removal of mitotic phosphorylation by protein phosphatases. Although protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) drive this reversal in animal cells, the phosphatase network associated with ordered bulk dephosphorylation in mitotic exit is not fully understood. Here, we describe a new mitotic phosphatase relay in which Wip1/PPM1D phosphatase activity is essential for chromosomal passenger complex (CPC) translocation to the anaphase central spindle after release from the chromosome via PP1-mediated dephosphorylation of histone H3T3. Depletion of endogenous Wip1 and overexpression of the phosphatase-dead mutant disturbed CPC translocation to the central spindle, leading to failure of cytokinesis. While Wip1 was degraded in early mitosis, its levels recovered in anaphase and the protein functioned as a Cdk1-counteracting phosphatase at the anaphase central spindle and midbody. Mechanistically, Wip1 dephosphorylated Thr-59 in inner centromere protein (INCENP), which, subsequently bound to MKLP2 and recruited other components to the central spindle. Furthermore, Wip1 overexpression is associated with the overall survival rate of patients with breast cancer, suggesting that Wip1 not only functions as a weak oncogene in the DNA damage network but also as a tumor suppressor in mitotic exit. Altogether, our findings reveal that sequential dephosphorylation of mitotic phosphatases provides spatiotemporal regulation of mitotic exit to prevent tumor initiation and progression.

Sensitivity to differential NRF1 gene signatures contributes to breast cancer disparities

PURPOSE

Nuclear respiratory factor 1 (NRF1) drives estrogen-dependent breast tumorigenesis. Herein we examined the impact of NRF1 activity on the aggressiveness and disparate molecular signature of breast cancer in Black, White, Asian, and Hispanic women.

METHODS

NRF1 activity by transcription factor target enrichment analysis and causal NRF1-target gene signatures by Bayesian Network Inference with Java Objects (BANJO) and Markov Chain Monte Carlo (MCMC)-based gene order were examined in The Cancer Genome Atlas (TCGA) breast cancer cohorts.

RESULTS

We are the first to report increased NRF1 activity based on its differential effects on genome-wide transcription associated with luminal A and B, HER2+ and triple-negative (TN) molecular subtypes of breast cancer in women of different race/ethnicity. We observed disparate NRF1 motif-containing causal gene signatures unique to Black, White, Asian, and Hispanic women for luminal A breast cancer. Further gene order searches showed molecular heterogeneity of each subtype of breast cancer. Six different gene order sequences involving CDK1, HMMR, CCNB2, CCNB1, E2F1, CREB3L4, GTSE1, and LMNB1 with almost equal weight predicted the probability of luminal A breast cancer in whites. Three different gene order sequences consisting of CCNB1 and GTSE1, and CCNB1, LMNB1, CDK1 or CASP3 predicted almost 100% probability of luminal B breast cancer in whites; CCNB1 and LMNB1 or GTSE predicted 100% HER2+ breast cancer in whites. GTSE1 and TUBA1C combined together predicted 100% probability of developing TNBC in whites; NRF1, TUBA1B and BAX with EFNA4, and NRF1 and BTRC predicated 100% TNBC in blacks. High expressor NRF1 TN breast tumors showed unfavorable prognosis with a high risk of breast cancer death in white women.

CONCLUSION

Our findings showed how sensitivity to high NRF1 transcriptional activity coupled with its target gene signatures contribute to racial differences in luminal A and TN breast cancer subtypes. This knowledge may be useful in personalized intervention to prevent and treat this clinically challenging problem.

The role of PPM1D in cancer and advances in studies of its inhibitors

A greater understanding of factors causing cancer initiation, progression and evolution is of paramount importance. Among them, the serine/threonine phosphatase PPM1D, also referred to as wild-type p53-induced phosphatase 1 (Wip1) or protein phosphatase 2C delta (PP2Cδ), is emerging as an important oncoprotein due to its negative regulation on a number of crucial cancer suppressor pathways. Initially identified as a p53-regulated gene, PPM1D has been afterwards found amplified and more recently mutated in many human cancers such as breast cancer. The latest progress in this field further reveals that selective inhibition of PPM1D to delay tumor onset or reduce tumor burden represents a promising anti-cancer strategy. Here, we review the advances in the studies of the PPM1D activity and its relevance to various cancers, and recent progress in development of PPM1D inhibitors and discuss their potential application in cancer therapy. Consecutive research on PPM1D and its relationship with cancer is essential, as it ultimately contributes to the etiology and treatment of cancer.

The role of DNA methylation in human trophoblast differentiation

The placenta is a vital fetal exchange organ connecting mother and baby. Specialised placental epithelial cells, called trophoblasts, are essential for adequate placental function. Trophoblasts transform the maternal vasculature to allow efficient blood flow to the placenta and facilitate adequate nutrient uptake. Placental development is in part regulated by epigenetic mechanisms. However, our understanding of how DNA methylation contributes to human trophoblast differentiation is limited. To better understand how genome-wide methylation differences affect trophoblast differentiation, reduced representation bisulfite sequencing (RRBS) was conducted on four matched sets of trophoblasts; side-population trophoblasts (a candidate human trophoblast stem cell population), cytotrophoblasts (an intermediate progenitor population), and extravillous trophoblasts (EVT, a terminally differentiated population) each isolated from the same first trimester placenta. Each trophoblast population had a distinct methylome. In line with their close differentiation relationship, the methylation profile of side-population trophoblasts was most similar to cytotrophoblasts, whilst EVT had the most distinct methylome. In comparison to mature trophoblast populations, side-population trophoblasts exhibited differential methylation of genes and miRNAs involved in cell cycle regulation, differentiation, and regulation of pluripotency. A combined methylomic and transcriptomic approach was taken to better understand cytotrophoblast differentiation to EVT. This revealed methylation of 41 genes involved in epithelial to mesenchymal transition and metastatic cancer pathways, which likely contributes to the acquisition of an invasive EVT phenotype. However, the methylation status of a gene did not always predict gene expression. Therefore, while CpG methylation plays a role in trophoblast differentiation, it is likely not the only regulatory mechanism involved in this process.

Caffeic Acid Versus Caffeic Acid Phenethyl Ester in the Treatment of Breast Cancer MCF-7 Cells: Migration Rate Inhibition

Epithelium mammary carcinoma is a cancer with a high death rate among women. One factor having a significant impact on metastasis is cell migration. The aim of this study was to compare migration rate inhibition of caffeic acid (CA) and its phenethyl ester (CAPE) on MCF-7 breast cancer cells. Microscopic evaluation was used to determine the morphology of carcinoma cells, before and after 24-hour treatment with CA and CAPE using a dose of 50 µM. The cytotoxic effect was measured by XTT-NR-SRB assay (tetrazolium hydroxide-neutral red-Sulforhodamine B) for 24-hour and 48-hour periods, using CA and CAPE, with doses of 50 and 100 µM. These doses were used to determine cell migration inhibition using a wound closure assay for 0-hour, 8-hour, 16-hour, and 24-hour periods. Both CA and CAPE treatments displayed cytotoxic activity in a dose- and time-dependent trend. CAPE displayed IC₅₀ values more than twice as low as CA. IC₅₀ values for the XTT assay were as follows: CA was 102.98 µM for 24 hours and 59.12 µM for 48 hours, while CAPE was 56.39 µM for 24 hours and 28.10 µM for 48 hours. For the NR assay: CA was 84.87 µM at 24 hours and 65.05 µM at 48 hours, while CAPE was 69.05 µM at 24 hours and 29.05 µM at 48 hours. For the SRB assay: At 24 hours, CA was 83.47 µM and 53.46 µM at 48 hours, while CAPE was 38.53 µM at 24 hours and 20.15 µM at 48 hours. Both polyphenols induced migration inhibition, resulting in practically halting the wound closure. CAPE produced better results than CA with the same doses and experiment times, though both CA and CAPE displayed cytotoxic activity against MCF-7 cells, as well as inhibited migration.

Significance of prohibitin domain family in tumorigenesis and its implication in cancer diagnosis and treatment

Prohibitin (PHB) was originally isolated and characterized as an anti-proliferative gene in rat liver. The evolutionarily conserved PHB gene encodes two human protein isoforms with molecular weights of ~33 kDa, PHB1 and PHB2. PHB1 and PHB2 belong to the prohibitin domain family, and both are widely distributed in different cellular compartments such as the mitochondria, nucleus, and cell membrane. Most studies have confirmed differential expression of PHB1 and PHB2 in cancers compared to corresponding normal tissues. Furthermore, studies verified that PHB1 and PHB2 are involved in the biological processes of tumorigenesis, including cancer cell proliferation, apoptosis, and metastasis. Two small molecule inhibitors, Rocaglamide (RocA) and fluorizoline, derived from medicinal plants, were demonstrated to interact directly with PHB1 and thus inhibit the interaction of PHB with Raf-1, impeding Raf-1/ERK signaling cascades and significantly suppressing cancer cell metastasis. In addition, a short peptide ERAP and a natural product xanthohumol were shown to target PHB2 directly and prohibit cancer progression in estrogen-dependent cancers. As more efficient biomarkers and targets are urgently needed for cancer diagnosis and treatment, here we summarize the functional role of prohibitin domain family proteins, focusing on PHB1 and PHB2 in tumorigenesis and cancer development, with the expectation that targeting the prohibitin domain family will offer more clues for cancer therapy.

High G2 and S-phase expressed 1 expression promotes acral melanoma progression and correlates with poor clinical prognosis

G2 and S‐phase expressed 1 (GTSE1) regulates cell cycle progression in human cancers. However, its significance and mechanism of action in acral melanoma (AM) remain unknown. In the present study, we found that GTSE1 expression was upregulated in advanced stage/metastatic AM tissues and metastatic cell lines, and correlated with higher stage (P = .028) and poor disease‐free survival (DFS) in patients with AM (P = .003). Cox regression assays validated GTSE1 expression to be an independent prognostic factor of DFS for patients with AM (P = .004). Ectopic expression of GTSE1 enhanced primary AM cell proliferation, invasion, and migration. Loss‐of‐function in GTSE1 attenuated metastatic AM cell proliferation and metastatic ability in vitro and in vivo. We additionally observed that inhibition of migration and invasion occurred concomitantly with a GTSE1 knockdown‐mediated increase in E‐cadherin and decreases in N‐cadherin and Slug. We further showed that integrin subunit alpha 2 (ITGA2) interacts with GTSE1 and is a downstream effector of GTSE1. Further, ITGA2 levels were positively correlated with GTSE1 expression in human AM tissues. Ectopic ITGA2 expression rescued siGTSE1‐mediated inhibition of migration and invasion, thereby restoring epithelial‐to‐mesenchymal transition (EMT). In conclusion, GTSE1 expression promotes AM progression and correlates with clinical outcomes of patients with AM, and may represent a promising therapeutic target to suppress AM progression.

Flavagline analog FL3 induces cell cycle arrest in urothelial carcinoma cell of the bladder by inhibiting the Akt/PHB interaction to activate the GADD45α pathway

Background

Prohibitin 1 (PHB) is a potential target for the treatment of urothelial carcinoma of the bladder (UCB). FL3 is a newly synthesized agent that inhibits cancer cell proliferation by targeting the PHB protein; however, the effect of FL3 in UCB cells remains unexplored.

Methods

FL3 was identified to be a potent inhibitor of UCB cell viability using CCK-8 (cell counting kit-8) assay. Then a series of in vitro and in vivo experiments were conducted to further demonstrate the inhibitory effect of FL3 on UCB cell proliferation and to determine the underlying mechanisms.

Results

FL3 inhibited UCB cell proliferation and growth both in vitro and in vivo. By targeting the PHB protein, FL3 inhibited the interaction of Akt and PHB as well as Akt-mediated PHB phosphorylation, which consequently decreases the localization of PHB in the mitochondria. In addition, FL3 treatment resulted in cell cycle arrest in the G2/M phase, and this inhibitory effect of FL3 could be mimicked by knockdown of PHB.

Through the microarray analysis of mRNA expression after FL3 treatment and knockdown of PHB, we found that the mRNA expression of the growth arrest and DNA damage-inducible alpha (GADD45α) gene were significantly upregulated. When knocked down the expression of GADD45α, the inhibitory effect of FL3 on cell cycle was rescued, suggesting that FL3-induced cell cycle inhibition is GADD45α dependent.

Conclusion

Our data provide that FL3 inhibits the interaction of Akt and PHB, which in turn activates the GADD45α-dependent cell cycle inhibition in the G2/M phase.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0695-5) contains supplementary material, which is available to authorized users.

Wip1: A candidate phosphatase for cancer diagnosis and treatment

The critical regulatory mechanisms in numerous cellular pathways including cell survival and DNA damage response mostly depend on phosphorylation and dephosphorylation of proteins. The serine/threonine phosphatase wild-type p53-induced phosphatase 1 (Wip1) is a growth-promoting phosphatase and its numerous downstream targets are important tumor suppressors. Here, we review the Wip1 activity and its relevance to cancer as an oncoprotein. Consecutive investigations about Wip1 and its relation to cancer is critical, as these studies ultimately contribute to the etiology of cancer. A number of innovative studies have recently investigated the importance of Wip1 as a new candidate for cancer diagnosis and prognosis. Accordingly, we discuss the present challenges of using Wip1 as a target for cancer treatment.

Analysis of molecular markers as predictive factors of lymph node involvement in breast carcinoma

Nodal status is the most significant independent prognostic factor in breast cancer. Identification of molecular markers would allow stratification of patients who require surgical assessment of lymph nodes from the large numbers of patients for whom this surgical procedure is unnecessary, thus leading to a more accurate prognosis. However, up to now, the reported studies are preliminary and controversial, and although hundreds of markers have been assessed, few of them have been used in clinical practice for treatment or prognosis in breast cancer. The purpose of the present study was to determine whether protein phosphatase Mg2+/Mn2+ dependent 1D, β-1,3-N-acetylglucosaminyltransferase, neural precursor cell expressed, developmentally down-regulated 9, prohibitin, phosphoinositide-3-kinase regulatory subunit 5 (PIK3R5), phosphatidylinositol-5-phosphate 4-kinase type IIα, TRF1-interacting ankyrin-related ADP-ribose polymerase 2, BCL2 associated agonist of cell death, G2 and S-phase expressed 1 and PAX interacting protein 1 genes, described as prognostic markers in breast cancer in a previous microarray study, are also predictors of lymph node involvement in breast carcinoma Reverse transcription-quantitative polymerase chain reaction analysis was performed on primary breast tumor tissues from women with negative lymph node involvement (n=27) compared with primary tumor tissues from women with positive lymph node involvement (n=23), and was also performed on primary tumors and paired lymph node metastases (n=11). For all genes analyzed, only the PIK3R5 gene exhibited differential expression in samples of primary tumors with positive lymph node involvement compared with primary tumors with negative lymph node involvement (P=0.0347). These results demonstrate that the PIK3R5 gene may be considered predictive of lymph node involvement in breast carcinoma. Although the other genes evaluated in the present study have been previously characterized to be involved with the development of distant metastases, they did not have predictive potential.