Super-silencer perturbation by EZH2 and REST inhibition leads to large loss of chromatin interactions and reduction in cancer growth.

Human silencers have been shown to regulate developmental gene expression. However, the functional importance of human silencers needs to be elucidated, such as whether they can form 'super-silencers' and whether they are linked to cancer progression. Here, we show two silencer components of the FGF18 gene can cooperate through compensatory chromatin interactions to form a super-silencer. Double knockout of two silencers exhibited synergistic upregulation of FGF18 expression and changes in cell identity. To perturb the super-silencers, we applied combinational treatment of an enhancer of zeste homolog 2 inhibitor GSK343, and a repressor element 1-silencing transcription factor inhibitor, X5050 ('GR'). Interestingly, GR led to severe loss of topologically associated domains and loops, which were associated with reduced CTCF and TOP2A mRNA levels. Moreover, GR synergistically upregulated super-silencer-controlled genes related to cell cycle, apoptosis and DNA damage, leading to anticancer effects in vivo. Overall, our data demonstrated a super-silencer example and showed that GR can disrupt super-silencers, potentially leading to cancer ablation.

GNA13 suppresses proliferation of ER+ breast cancer cells via ERα dependent upregulation of the MYC oncogene.

GNA13 (Gα13) is one of two alpha subunit members of the G12/13 family of heterotrimeric G-proteins which mediate signaling downstream of GPCRs. It is known to be essential for embryonic development and vasculogenesis and has been increasingly shown to be involved in mediating several steps of cancer progression. Recent studies found that Gα13 can function as an oncogene and contributes to progression and metastasis of multiple tumor types, including ovarian, head and neck and prostate cancers. In most cases, Gα12 and Gα13, as closely related α-subunits in the subfamily, have similar cellular roles. However, in recent years their differences in signaling and function have started to emerge. We previously identified that Gα13 drives invasion of Triple Negative Breast Cancer (TNBC) cells in vitro. As a highly heterogenous disease with various well-defined molecular subtypes (ER+ /Her2-, ER+ /Her2+, Her2+, TNBC) and subtype associated outcomes, the function(s) of Gα13 beyond TNBC should be explored. Here, we report the finding that low expression of GNA13 is predictive of poorer survival in breast cancer, which challenges the conventional idea of Gα12/13 being universal oncogenes in solid tumors. Consistently, we found that Gα13 suppresses the proliferation in multiple ER+ breast cancer cell lines (MCF-7, ZR-75-1 and T47D). Loss of GNA13 expression drives cell proliferation, soft-agar colony formation and in vivo tumor formation in an orthotopic xenograft model. To evaluate the mechanism of Gα13 action, we performed RNA-sequencing analysis on these cell lines and found that loss of GNA13 results in the upregulation of MYC signaling pathways in ER+ breast cancer cells. Simultaneous silencing of MYC reversed the proliferative effect from the loss of GNA13, validating the role of MYC in Gα13 regulation of proliferation. Further, we found Gα13 regulates the expression of MYC, at both the transcript and protein level in an ERα dependent manner. Taken together, our study provides the first evidence for a tumor suppressive role for Gα13 in breast cancer cells and demonstrates for the first time the direct involvement of Gα13 in ER-dependent regulation of MYC signaling. With a few exceptions, elevated Gα13 levels are generally considered to be oncogenic, similar to Gα12. This study demonstrates an unexpected tumor suppressive role for Gα13 in ER+ breast cancer via regulation of MYC, suggesting that Gα13 can have subtype-dependent tumor suppressive roles in breast cancer.

Mono-2-ethylhexylphthalate (MEHP) is a potent agonist of human TRPA1 channel.

Phthalates are extensively used as plasticizers in diverse consumer care products but have been reported to cause adverse health effects in humans. A commonly used phthalate, di-2-ethylhexylphthalate (DEHP) causes developmental and reproductive toxicities in humans, but the associated molecular mechanisms are not fully understood. Mono-2-ethylhexylphthalate (MEHP), a hydrolytic product of DEHP generated by cellular esterases, is proposed to be the active toxicant. We conducted a screen for sensory irritants among compounds used in consumer care using an assay for human Transient Receptor Potential A1 (hTRPA1). We have identified MEHP as a potent agonist of hTRPA1. MEHP-induced hTRPA1 activation was blocked by the TRPA1 inhibitor A-967079. Patch clamp assays revealed that MEHP induced inward currents in cells expressing hTRPA1. In addition, the N855S mutation in hTRPA1 associated with familial episodic pain syndrome decreased MEHP-induced hTRPA1 activation. In summary, we report that MEHP is a potent agonist of hTRPA1 which generates new possible mechanisms for toxic effects of phthalates in humans.

Dynamic altruistic cooperation within breast tumors.

BACKGROUND: Social behaviors such as altruism, where one self-sacrifices for collective benefits, critically influence an organism's survival and responses to the environment. Such behaviors are widely exemplified in nature but have been underexplored in cancer cells which are conventionally seen as selfish competitive players. This multidisciplinary study explores altruism and its mechanism in breast cancer cells and its contribution to chemoresistance. METHODS: MicroRNA profiling was performed on circulating tumor cells collected from the blood of treated breast cancer patients. Cancer cell lines ectopically expressing candidate miRNA were used in co-culture experiments and treated with docetaxel. Ecological parameters like relative survival and relative fitness were assessed using flow cytometry. Functional studies and characterization performed in vitro and in vivo include proliferation, iTRAQ-mass spectrometry, RNA sequencing, inhibition by small molecules and antibodies, siRNA knockdown, CRISPR/dCas9 inhibition and fluorescence imaging of promoter reporter-expressing cells. Mathematical modeling based on evolutionary game theory was performed to simulate spatial organization of cancer cells. RESULTS: Opposing cancer processes underlie altruism: an oncogenic process involving secretion of IGFBP2 and CCL28 by the altruists to induce survival benefits in neighboring cells under taxane exposure, and a self-sacrificial tumor suppressive process impeding proliferation of altruists via cell cycle arrest. Both processes are regulated concurrently in the altruists by miR-125b, via differential NF-κB signaling specifically through IKKß. Altruistic cells persist in the tumor despite their self-sacrifice, as they can regenerate epigenetically from non-altruists via a KLF2/PCAF-mediated mechanism. The altruists maintain a sparse spatial organization by inhibiting surrounding cells from adopting the altruistic fate via a lateral inhibition mechanism involving a GAB1-PI3K-AKT-miR-125b signaling circuit. CONCLUSIONS: Our data reveal molecular mechanisms underlying manifestation, persistence and spatial spread of cancer cell altruism. A minor population behave altruistically at a cost to itself producing a collective benefit for the tumor, suggesting tumors to be dynamic social systems governed by the same rules of cooperation in social organisms. Understanding cancer cell altruism may lead to more holistic models of tumor evolution and drug response, as well as therapeutic paradigms that account for social interactions. Cancer cells constitute tractable experimental models for fields beyond oncology, like evolutionary ecology and game theory.

WNTinib is a multi-kinase inhibitor with specificity against ß-catenin mutant hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. ß-Catenin (CTNNB1)-mutated HCC represents 30% of cases of the disease with no precision therapeutics available. Using chemical libraries derived from clinical multi-kinase inhibitor (KI) scaffolds, we screened HCC organoids to identify WNTinib, a KI with exquisite selectivity in CTNNB1-mutated human and murine models, including patient samples. Multiomic and target engagement analyses, combined with rescue experiments and in vitro and in vivo efficacy studies, revealed that WNTinib is superior to clinical KIs and inhibits KIT/mitogen-activated protein kinase (MAPK) signaling at multiple nodes. Moreover, we demonstrate that reduced engagement on BRAF and p38α kinases by WNTinib relative to several multi-KIs is necessary to avoid compensatory feedback signaling-providing a durable and selective transcriptional repression of mutant ß-catenin/Wnt targets through nuclear translocation of the EZH2 transcriptional repressor. Our studies uncover a previously unknown mechanism to harness the KIT/MAPK/EZH2 pathway to potently and selectively antagonize CTNNB1-mutant HCC with an unprecedented wide therapeutic index.

Dependency of NELF-E-SLUG-KAT2B epigenetic axis in breast cancer carcinogenesis.

Cancer cells undergo transcriptional reprogramming to drive tumor progression and metastasis. Using cancer cell lines and patient-derived tumor organoids, we demonstrate that loss of the negative elongation factor (NELF) complex inhibits breast cancer development through downregulating epithelial-mesenchymal transition (EMT) and stemness-associated genes. Quantitative multiplexed Rapid Immunoprecipitation Mass spectrometry of Endogenous proteins (qPLEX-RIME) further reveals a significant rewiring of NELF-E-associated chromatin partners as a function of EMT and a co-option of NELF-E with the key EMT transcription factor SLUG. Accordingly, loss of NELF-E leads to impaired SLUG binding on chromatin. Through integrative transcriptomic and genomic analyses, we identify the histone acetyltransferase, KAT2B, as a key functional target of NELF-E-SLUG. Genetic and pharmacological inactivation of KAT2B ameliorate the expression of EMT markers, phenocopying NELF ablation. Elevated expression of NELF-E and KAT2B is associated with poorer prognosis in breast cancer patients, highlighting the clinical relevance of our findings. Taken together, we uncover a crucial role of the NELF-E-SLUG-KAT2B epigenetic axis in breast cancer carcinogenesis.

PLK1 inhibition selectively induces apoptosis in ARID1A deficient cells through uncoupling of oxygen consumption from ATP production.

Inhibitors of the mitotic kinase PLK1 yield objective responses in a subset of refractory cancers. However, PLK1 overexpression in cancer does not correlate with drug sensitivity, and the clinical development of PLK1 inhibitors has been hampered by the lack of patient selection marker. Using a high-throughput chemical screen, we discovered that cells deficient for the tumor suppressor ARID1A are highly sensitive to PLK1 inhibition. Interestingly this sensitivity was unrelated to canonical functions of PLK1 in mediating G2/M cell cycle transition. Instead, a whole-genome CRISPR screen revealed PLK1 inhibitor sensitivity in ARID1A deficient cells to be dependent on the mitochondrial translation machinery. We find that ARID1A knock-out (KO) cells have an unusual mitochondrial phenotype with aberrant biogenesis, increased oxygen consumption/expression of oxidative phosphorylation genes, but without increased ATP production. Using expansion microscopy and biochemical fractionation, we see that a subset of PLK1 localizes to the mitochondria in interphase cells. Inhibition of PLK1 in ARID1A KO cells further uncouples oxygen consumption from ATP production, with subsequent membrane depolarization and apoptosis. Knockdown of specific subunits of the mitochondrial ribosome reverses PLK1-inhibitor induced apoptosis in ARID1A deficient cells, confirming specificity of the phenotype. Together, these findings highlight a novel interphase role for PLK1 in maintaining mitochondrial fitness under metabolic stress, and a strategy for therapeutic use of PLK1 inhibitors. To translate these findings, we describe a quantitative microscopy assay for assessment of ARID1A protein loss, which could offer a novel patient selection strategy for the clinical development of PLK1 inhibitors in cancer.

A rare presentation of solitary pineal region metastasis in a case of lung cancer.

Pineal gland metastasis accounts for approximately 0.4% of all intracranial metastases from lung primary. Our patient was a 60-year-old female presenting with intermittent headache and altered sensorium. Magnetic resonance imaging brain showed a 21 mm × 18 mm × 16 mm pineal lesion with obstructive hydrocephalus. She underwent endoscopic third ventriculostomy and drainage. Fluorodeoxyglucose-PET showed a left lung primary tumor with nodal metastasis and solitary pineal gland metastasis. Biopsy of lung lesion revealed poorly differentiated non-small-cell carcinoma which was treated with focal pineal radiation and chemotherapy. This patient's presentation is unique because she presented with pineal symptoms rather than lung symptoms. Pineal gland metastasis from lung primary is mostly associated with small-cell carcinoma histology, but this patient had a non-small-cell carcinoma of lung primary. The age above 60 years is in favor of a metastatic lesion to the pineal gland. Our experience suggests that systemic evaluation of all patients presenting initially with an isolated pineal gland tumor is mandatory.

Study of tumor transglutaminase 2 expression in gallbladder cancer - Is it a novel predictor of survival?

BACKGROUNDS/AIMS: Transglutaminase 2 (TG2) is known to be an important mediator of inflammation induced carcinogenesis pathway. Chronic inflammation is the most important causative factor in Gallbladder cancer (GBC) carcinogenesis. We analyzed the expression of TG2 in GBC and its role as potential prognostic marker, first of its kind study. METHODS: We analyzed TG2 expression in 100 cases of GBC and 28 cases of non-cancer gallbladder specimen (calculus cholecystitis). We studied TG2 expression in GBC in comparison to control group and evaluated its role as a potential prognostic marker. RESULTS: TG2 score (1-9) was calculated by multiplying percentage cytoplasmic expression (P) with intensity of expression (I) in tumor cells. Positive TG-2 expression was observed in 62% of GBC patients compared to only 21% (n=6) in control group (p=0.001). In curative resection subgroup (n=54), TG2 positive patients showed shorter disease free survival rate (p=0.04) and higher rate of recurrence (p=0.03) compared to TG2 negative patients. TG2 positive expression was observed in 15/16 of patients with recurrent disease. In palliative treatment subgroup, patients with strong TG2 positive expression had poorer disease specific survival (p=0.01) as compared to weakly positive group. On multivariate analysis, lymph node status (p=0.03) and TG2 expression (p=0.037), were found to be significant predictor of recurrence and eventual survival. CONCLUSIONS: Positive TG2 expression was related to higher recurrence rates post curative surgery, shorter disease free and overall survival and ultimately portended poor prognosis. It may be helpful in better prognostication and tailoring therapeutic approach for better management of GBC.

Targeting N-myristoylation for therapy of B-cell lymphomas.

Myristoylation, the N-terminal modification of proteins with the fatty acid myristate, is critical for membrane targeting and cell signaling. Because cancer cells often have increased N-myristoyltransferase (NMT) expression, NMTs were proposed as anti-cancer targets. To systematically investigate this, we performed robotic cancer cell line screens and discovered a marked sensitivity of hematological cancer cell lines, including B-cell lymphomas, to the potent pan-NMT inhibitor PCLX-001. PCLX-001 treatment impacts the global myristoylation of lymphoma cell proteins and inhibits early B-cell receptor (BCR) signaling events critical for survival. In addition to abrogating myristoylation of Src family kinases, PCLX-001 also promotes their degradation and, unexpectedly, that of numerous non-myristoylated BCR effectors including c-Myc, NFκB and P-ERK, leading to cancer cell death in vitro and in xenograft models. Because some treated lymphoma patients experience relapse and die, targeting B-cell lymphomas with a NMT inhibitor potentially provides an additional much needed treatment option for lymphoma.

PRDM15 is a key regulator of metabolism critical to sustain B-cell lymphomagenesis.

PRDM (PRDI-BF1 and RIZ homology domain containing) family members are sequence-specific transcriptional regulators involved in cell identity and fate determination, often dysregulated in cancer. The PRDM15 gene is of particular interest, given its low expression in adult tissues and its overexpression in B-cell lymphomas. Despite its well characterized role in stem cell biology and during early development, the role of PRDM15 in cancer remains obscure. Herein, we demonstrate that while PRDM15 is largely dispensable for mouse adult somatic cell homeostasis in vivo, it plays a critical role in B-cell lymphomagenesis. Mechanistically, PRDM15 regulates a transcriptional program that sustains the activity of the PI3K/AKT/mTOR pathway and glycolysis in B-cell lymphomas. Abrogation of PRDM15 induces a metabolic crisis and selective death of lymphoma cells. Collectively, our data demonstrate that PRDM15 fuels the metabolic requirement of B-cell lymphomas and validate it as an attractive and previously unrecognized target in oncology.

Validation of the Brandwein Gensler Risk Model in Patients of Oral Cavity Squamous Cell Carcinoma in North India.

India has one of the highest incidences of oral squamous cell carcinoma (OSCC), with 75,000-80,000 new cases a year. The outcome in early oral cancer is better, but a significant proportion (12-14%) of these patients still relapses and dies due to locoregional or distant recurrences. Several clinicopathological and molecular factors have been used to prognosticate and predict outcomes in these patients of OSCC. The present study aims to validate Brandwein Gensler (BG) risk predictive model in surgically treated OSCC patients in a tertiary care centre in North India. All oral cavity cancer patients, treated in the Department of Surgical Oncology, King George's Medical University, between 2013 and 2017, were reviewed. Patients with histologically diagnosed OSCC, aged > 18 years undergoing primary surgical resection were included in the study. The final histopathological evaluation was done by a dedicated pathologist to categorize patients according to BG model risk categories. This model comprises of three factors, lymphocytic host response, perineural invasion and worst pattern of invasion, scored by the method described by Brandwein Gensler et al. The sum of these scores is used to define low, moderate and high risk categories. The study, conducted during 2013-2017, included 149 patients. Median age was 45 years (range 25-75 years). Tobacco use was noted in 143 patients. Buccal mucosa was the most common site (51%). Surgical margins were clear (> 5 mm) in 97.9% cases. Postoperative radiotherapy was given in 47.7% patients. Locoregional recurrences (LRR) (primary site and neck) were documented in 17 of the 149 patients (11.4%). There was no synchronous or metachronous distant metastasis noted in any of the study patients. Six patients had disease specific mortality. Among the 17 patients with LRR, majority (11) belonged to the high risk category of the BG risk model. Adjuvant radiotherapy had been administered in 10 of these 11 recurrent patients belonging to the high risk category. The Brandwein Gensler risk model is predictive of locoregional recurrences (p = 0.02) for OSCC undergoing primary surgery. It can be used to devise strategies to prevent recurrences or identification of recurrences at an earlier point for salvage. The benefit of further escalation of adjuvant therapy in the high risk category needs further studies, as 90% patients in this group recurred despite complete adjuvant treatment.

Role of serum HE4 as a prognostic marker in carcinoma of the ovary.

BACKGROUND: Epithelial ovarian cancer is the second most common gynecological cancer. Human Epididymis Protein 4 is a novel biomarker for ovarian cancer. This study aims to explore the role of HE4 in monitoring recurrence and prognostication of ovarian cancer by predicting overall survival (OS) and progression-free survival (PFS). MATERIALS AND METHODS: In total, 149 patients with ovarian carcinoma were enrolled in the study. Baseline and post-treatment 3 monthly biomarker levels were recorded. For analysis, patients were divided into primary debulking surgery (PDS) and interval debulking surgery (IDS) groups. Statistical analysis was done using SPSS 24. RESULTS: Median age of patients at diagnosis was 45 (19-75) years. Recurrence was seen in 68.5% (n = 102) patients. The sensitivity of serum HE4 in detecting recurrence was 85.3% (95%CI: 76.95%-91.5%) and specificity was 91.5% (95%CI: 89.5%-98.2%). A >80% decline in HE4 levels during treatment indicated a better PFS, which was statistically significant in both groups (P = 0.04 in PDS and P = <0.001 in IDS group). Multivariate analysis suggested that OS was influenced by optimal cytoreduction in both groups of patients and stage in the IDS group. On the contrary, PFS was influenced by stage and response in HE4 levels in both groups. CONCLUSION: HE4 levels have similar sensitivity but more specificity when compared with CA125 in diagnosing recurrent ovarian cancer. A >80% decline in HE4 levels during treatment predicts better PFS and can help in prognostication.

A Role of Agrin in Maintaining the Stability of Vascular Endothelial Growth Factor Receptor-2 during Tumor Angiogenesis.

Endothelial cell (EC) recruitment is central to the vascularization of tumors. Although several proteoglycans have been implicated in cancer and angiogenesis, their roles in EC recruitment and vascularization during tumorigenesis remain poorly understood. Here, we reveal that Agrin, which is secreted in liver cancer, promotes angiogenesis by recruiting ECs within tumors and metastatic lesions and facilitates adhesion of cancer cells to ECs. In ECs, Agrin-induced angiogenesis and adherence to cancer cells are mediated by Integrin-ß1, Lrp4-MuSK pathways involving focal adhesion kinase. Mechanistically, we uncover that Agrin regulates VEGFR2 levels that sustain the angiogenic property of ECs and adherence to cancer cells. Agrin attributes an ECM stiffness-based stabilization of VEGFR2 by enhancing interactions with Integrin-ß1-Lrp4 and additionally stimulates endothelial nitric-oxide synthase (e-NOS) signaling. Therefore, we propose that cross-talk between Agrin-expressing cancer and ECs favor angiogenesis by sustaining the VEGFR2 pathway.

Germ Cell Tumor Ovary: an Institutional Experience of Treatment and Survival Outcomes.

Malignant germ cell tumors (GCT) of the ovary account for 2-3% of all ovarian neoplasms and occur mostly in the second and third decade of life. Over the past three decades, survival rates for germ cell tumors have dramatically improved, coincident with more aggressive surgical staging and combination chemotherapy. Although there are several studies describing ovarian GCT and fertility-preserving surgery in the western population, there is very little Indian data. We present our experience of germ cell tumor ovary in the Department of Surgical Oncology, King George's Medical University over the last 5 years with special emphasis on treatment outcome and role of fertility preservation surgery. A retrospective review of medical records of patients with ovarian germ cell tumors, treated at our center from January 2012 to December 2016, was performed. Epidemiological and clinical profile of patients was reviewed. Clinical stage of presentation, neoadjuvant treatment, surgical treatment, and adjuvant treatment data were analyzed, and treatment outcome data was recorded. Patient follow-up was done to ascertain disease-free interval, treatment outcome, ability to conceive following fertility-preserving surgery, and quality of life. A total of 39 patients with ovarian germ cell tumor were treated during this period. Their median age at diagnosis was 22 years (range 11-65 years) and most common mode of presentation was abdominal lump without ascites. Around 36.8% (n = 14) patients had conservative surgery with preservation of opposite ovary and uterus. Most patients (71.1% n = 27) received neoadjuvant chemotherapy due to advanced disease in form of ascites or large mass, and five of these patients were amenable to fertility-preserving surgery after chemotherapy. Nine out of the fourteen patients have had return of menstrual function after a mean period of 3.5 + 0.5 months. One patient who underwent fertility-preserving surgery has delivered healthy children after treatment. Stage distribution for stage I to IV was as follows: 15.4% (n = 6), 35.9% (n = 14), 46.2% (n = 18), and 2.6% (n = 1), respectively. Dysgerminoma was the commonest histology (37.1% n = 13) followed by teratoma (22.9% n = 8). 17.1% (n = 6) patients had recurrence, with a median time to recurrence 16 months (range 5.5 to 37 months) and they were treated with second-line chemotherapy. Germ cell tumor of the ovary is an eminently treatable disease and selected patients can be managed with fertility-preserving surgery. BEP is the most effective chemotherapy regimen. Disease-free survival rates in these patients are quite high and recurrences can be managed with second-line chemotherapy.

Correction: Role of novel histone modifications in cancer.

[This corrects the article DOI: 10.18632/oncotarget.23356.].

Role of novel histone modifications in cancer.

Oncogenesis is a multistep process mediated by a variety of factors including epigenetic modifications. Global epigenetic post-translational modifications have been detected in almost all cancers types. Epigenetic changes appear briefly and do not involve permanent changes to the primary DNA sequence. These epigenetic modifications occur in key oncogenes, tumor suppressor genes, and transcription factors, leading to cancer initiation and progression. The most commonly observed epigenetic changes include DNA methylation, histone lysine methylation and demethylation, histone lysine acetylation and deacetylation. However, there are several other novel post-translational modifications that have been observed in recent times such as neddylation, sumoylation, glycosylation, phosphorylation, poly-ADP ribosylation, ubiquitination as well as transcriptional regulation and these have been briefly discussed in this article. We have also highlighted the diverse epigenetic changes that occur during the process of tumorigenesis and described the role of histone modifications that can occur on tumor suppressor genes as well as oncogenes, which regulate tumorigenesis and can thus form the basis of novel strategies for cancer therapy.

Development and evaluation of camptothecin loaded polymer stabilized nanoemulsion: Targeting potential in 4T1-breast tumour xenograft model.

Targeted delivery of anticancer agents is poised to improve cancer therapy, for which polymers can serve as targeting ligands or nanocarriers for chemotherapeutic agents. In this study, we have developed and evaluated the efficacy of a camptothecin (CPT)-loaded polymer stabilized nanoemulsion (PSNE) for the passive targeted delivery to breast cancer. Based on the pseudo-ternary phase diagrams, PSNEs were developed using capmul MCM:poloxamer 407 (4:1), solutol HS 15:simulsol P23 (1:2) and water. CPT polymer mixture was developed by solvent evaporation technique. The PSNEs were characterized for droplet size distribution, plasma protein adsorption, drug release, in-vivo targeting potential, hemolytic potential, cytotoxicity, genotoxicity, in-vivo biodistribution and CPT lactone ring stability. The developed PSNEs showed uniform droplet distribution, extended drug release (76.59±6.12% at 24h), acceptable hemolytic potential, significant cytotoxicity (IC50=176±4.3ng/mL) and genotoxicity against MCF-7 cancer cells but low DNA damage potential in human peripheral blood lymphocytes. The efficiency of PSNEs for the targeted delivery of CPT into the tumour regions was documented in 4T1-breast tumour xenografted BALB/c mice. In-vivo biodistribution study shows that 7105.84±568.46ng/g of CPT was passively targeted from PSNE to breast cancer tissue. About 80% of the lactone form was stable for 24h. Taken together, our study provides a promising strategy for developing PSNE-targeted drug delivery system for the breast cancer therapy.