Combinatorial cetuximab targeted polymeric nanocomplexes reduce PRC1 level and abrogate growth of metastatic hepatocellular carcinoma in vivo with efficient radionuclide uptake.

Hepatocellular carcinoma (HCC) is the most aggressive form of cancer with poor drug responses. Developing an effective drug treatment remains a major unmet clinical need for HCC. We report a comprehensive study of combinatorial Cetuximab (Cet) targeted polymeric poly(D, L-lactide-co-glycolide)-b-poly(ethylene glycol) nanocomplexes delivery of Combretastatin A4 (CA4) and 2-Methoxyestradiol (2ME) (Cet-PLGA-b-PEG-CA4 NP + Cet-PLGA-b-PEG-2ME NP) against metastatic HCC in SCID mice. 125I-Cet-PLGA-b-PEG NP showed potent accumulation and retention in HCC tumors with longer circulation time up to 48 h (18 ±â€¯1.0% ID/g, P < .0001). Combinatorial treatment with targeted polymeric nanocomplexes presented significant tumor growth inhibition (85%, P < .0001) than the free drug combinatorial counterpart, effectively inhibited orthotopic HCC and prevented lung metastasis. Combinatorial nanocomplexes treatment significantly blocked PRC1, a novel target of therapeutic response against HCC. Thus, the combinatorial cetuximab-targeted polymeric nanocomplexes possess superior antitumor activity against metastatic HCC and provide supports for the clinical translation ahead.

Establishing a correlation between RIN and A260/280 along with the multivariate evaluation of factors affecting the quality of RNA in cryopreserved cancer bio-specimen.

Biomarkers are biological characteristic to measure and evaluate normal and pathological states. To define expression-based molecular biomarkers, high-quality tissue samples are a prerequisite for the preparation of standard RNA. It is already known that RIN number defines the RNA quality, however its relation with A260/280 ratio and Ct value is not defined clearly; therefore, understanding an association will provide a reliable method for describing RNA quality. Multiple cryopreserved human tumor tissue types from ACTREC Biorepository and TMH-INTTR were analyzed for the effect of storage time on RNA quality. The RNA from tumor samples were isolated and analyzed by RIN, A260/280 ratio, and Ct value to establish inter-relationships. Around 50% samples had a RIN of ≥ 6.9 and A260/280 ≤ 2.04; 27% had a RIN ≥ 5 and A260/280 ≤ 2.08, and remaining 23% displayed RIN < 5 and A260/280 > 2.08. However, the RNA quality has no association with the storage period of tissue samples. Moreover, all samples which had A260/280 ≤ 2.08 showed acceptable Ct values of 17-24. The data clearly suggests that the A260/280 ratio is able to predict RNA quality. To the best of our knowledge, this is the first Indian report analyzing the labile nucleic acid-RNA quality from different cancer tissue types cryopreserved for diverse time periods. In conclusion, RIN and A260/280 ratio can help in predicting the quality of RNA independently; however, both together provide better assurance for further downstream processing.

sPLA2 -IIA Overexpression in Mice Epidermis Depletes Hair Follicle Stem Cells and Induces Differentiation Mediated Through Enhanced JNK/c-Jun Activation.

Secretory phospholipase A2 Group-IIA (sPLA2 -IIA) catalyzes the hydrolysis of the sn-2 position of glycerophospholipids to yield fatty acids and lysophospholipids. sPLA2 -IIA is deregulated in various cancers; however, its role in hair follicle stem cell (HFSC) regulation is obscure. Here we report a transgenic mice overexpressing sPLA2 -IIA (K14-sPLA2 -IIA) showed depletion of HFSC pool. This was accompanied with increased differentiation, loss of ortho-parakeratotic organization and enlargement of sebaceous gland, infundibulum and junctional zone. The colony forming efficiency of keratinocytes was significantly reduced. Microarray profiling of HFSCs revealed enhanced level of epithelial mitogens and transcription factors, c-Jun and FosB that may be involved in proliferation and differentiation. Moreover, K14-sPLA2 -IIA keratinocytes showed enhanced activation of EGFR and JNK1/2 that led to c-Jun activation, which co-related with enhanced differentiation. Further, depletion of stem cells in bulge is associated with high levels of chromatin silencing mark, H3K27me3 and low levels of an activator mark, H3K9ac suggestive of alteration in gene expression contributing toward stem cells differentiation. Our results, first time uncovered that overexpression of sPLA2 -IIA lead to depletion of HFSCs and differentiation associated with altered histone modification. Thus involvement of sPLA2 -IIA in stem cells regulation and disease pathogenesis suggest its prospective clinical implications. Stem Cells 2016;34:2407-2417.

Histone acetylation: a key determinant of acquired cisplatin resistance in cancer.

Cisplatin is an alkylating class of chemotherapeutic drugs used to treat cancer patients. However, cisplatin fails in long-term treatment, and drug resistance is the primary reason for tumor recurrence. Hence, understanding the mechanism of acquirement of chemoresistance is essential for developing novel combination therapeutic approaches. In this study, in vitro cisplatin-resistant cancer cell line models were developed. Gene ontology and GSEA of differentially expressed genes between parental and resistant cells suggest that PI3K-AKT signaling, central carbon metabolism, and epigenetic-associated phenomenon alter in cisplatin-resistant cells. Further, the data showed that increased glucose transport, alteration in the activity of histone-modifying enzymes, and acetyl-CoA levels in resistant cells paralleled an increase in global histone acetylation. Enrichment of histone acetylation on effectors of PI3K-AKT and glycolysis pathway provides evidence of epigenetic regulation of the key molecules in drug resistance. Moreover, cisplatin treatment to resistant cells showed no significant changes in histone acetylation marks since drug treatment alters cell epigenome. In continuation, targeting PI3K-AKT signaling and glycolysis leads to alteration in histone acetylation levels and re-sensitization of resistant cells to chemo-drug. The data provide evidence of histone acetylation's importance in regulating pathways and cisplatin-resistant cells' cell survival. Our study paves the way for new approaches for developing personalized therapies in affecting metabolic pathways and epigenetic changes to achieve better outcomes for targeting drug-resistant cells.

An increase in polyadenylation of histone isoforms, Hist1h2ah and Hist2h3c2, is governed by 3'-UTR in de-differentiated and undifferentiated hepatocyte.

Replication-dependent histones have a stem-loop structure at the 3' end of messenger RNA (mRNA) and are stabilized by stem-loop binding protein (SLBP). Moreover, loss of SLBP and imbalance in the level of ARE (adenylate-uridylate-rich elements)-binding proteins, HuR, and BRF1 are associated with the polyadenylation of canonical histone mRNAs under different physiological conditions. Previous studies from the lab have shown increased protein levels of H2A1H and H3.2 in N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma (HCC). In this study, we report that increase in the polyadenylation of histone mRNA contributes to increased levels of H2A1H and H3.2 in NDEA-induced HCC. The persistent exposure to carcinogen with polyadenylation of histone mRNA increases the total histone pool resulting in aneuploidy. The embryonic liver has also shown increased polyadenylated histone isoforms, Hist1h2ah and Hist2h3c2, primarily contributing to their increased protein levels. The increase in polyadenylation of histone mRNA in HCC and e15 are in coherence with the decrease in SLBP and BRF1 with an increase in HuR. Our studies in neoplastic CL38 cell line showed that direct stress on the cells induces downregulation of SLBP with enhanced histone isoform polyadenylation. Moreover, the polyadenylation is related to increase in activated MAP kinases, p38, ERK, and JNK in HCC liver tumor tissues and CL38 cells treated with arsenic. Our data suggest that SLBP degrades under stress, destabilizing the stem-loop, elongating histone isoforms mRNA with 3' polyadenylated tail with increase of HuR and decrease of BRF1. Overall, our results indicate that SLBP may play an essential part in cell proliferation, at least in persistent exposure to stress, by mediating the stabilization of histone isoforms throughout the cell cycle.

Histone deacetylase inhibitor pre-treatment enhances the efficacy of DNA-interacting chemotherapeutic drugs in gastric cancer.

BACKGROUND: The prognosis of gastric cancer continues to remain poor, and epigenetic drugs like histone deacetylase inhibitors (HDACi) have been envisaged as potential therapeutic agents. Nevertheless, clinical trials are facing issues with toxicity and efficacy against solid tumors, which may be partly due to the lack of patient stratification for effective treatments. AIM: To study the need of patient stratification before HDACi treatment, and the efficacy of pre-treatment of HDACi as a chemotherapeutic drug sensitizer. METHODS: The expression activity of class 1 HDACs and histone acetylation was examined in human gastric cancer cells and tissues. The potential combinatorial regime of HDACi and chemotherapy drugs was defined on the basis of observed drug binding assays, chromatin remodeling and cell death. RESULTS: In the present study, the data suggest that the differential increase in HDAC activity and the expression of class 1 HDACs are associated with hypo-acetylation of histone proteins in tumors compared to normal adjacent mucosa tissue samples of gastric cancer. The data highlights for the first time that pre-treatment of HDACi results in an increased amount of DNA-bound drugs associated with enhanced histone acetylation, chromatin relaxation and cell cycle arrest. Fraction-affected plots and combination index-based analysis show that pre-HDACi chemo drug combinatorial regimes, including valproic acid with cisplatin or oxaliplatin and trichostatin A with epirubicin, exhibit synergism with maximum cytotoxic potential due to higher cell death at low combined doses in gastric cancer cell lines. CONCLUSION: Expression or activity of class 1 HDACs among gastric cancer patients present an effective approach for patient stratification. Furthermore, HDACi therapy in pre-treatment regimes is more effective with chemotherapy drugs, and may aid in predicting individual patient prognosis.

Repositioning of Difluorinated Propanediones as Inhibitors of Histone Methyltransferases and their Biological Evaluation in Human Leukemic Cell Lines.

BACKGROUND: At present, 'pharmaco-epigenomics' constitutes the hope in cancer treatment owing to epigenetic deregulation- a reversible process and playing a role in malignancy. OBJECTIVE: Chemotherapy has many limitations like host-tissue toxicity, drug resistance. Hence, it is imperative to unearth targets to better treat cancer. Here, we intend to repurpose a set of our previously synthesized difluorinated Propanediones (PR) as Histone lysine Methyltransferase inhibitors (HMTi). METHODS: The cell lines of leukemic origin viz. histiocytic lymphoma (U937) and acute T-cell leukemia (JURKAT) were treated with PR-1 to 7 after docking studies with active pocket of HMT. The cell cycle analysis, in vitro methylation and cell proliferation assays were carried out to delineate their physiological role. RESULTS: A small molecule PR-4, at 1 and 10µM, has shown to alter the methylation of histone H3 and H4 in both cell lines. Also, treatment shows an increase in G2/M population and a subsequent decrease in the G0/G1 population in U937. In JURKAT, an increase in both G2/M and S phase population was observed. The sub-G1 population showed a steady rise with increase in dose and prolonged time intervals in U937 and JURKAT cell lines. In SRB assay, the PR showed a cell growth of 42.6 and 53.4% comparable to adriamycin; 44.5 and 53.2% in U937 and JURKAT, respectively. The study suggests that PR-4 could emerge as a potential HMT inhibitor. CONCLUSION: The molecule PR-4 could be a lead in developing more histone lysine methyltransferases inhibitors with potential to be pro-apoptotic agents.

A novel method for isolation of histones from serum and its implications in therapeutics and prognosis of solid tumours.

BACKGROUND: Dysregulation in post-translational modifications of histones and their modifiers are now well-recognized as a hallmark of cancer and can be used as biomarkers and potential therapeutic targets for disease progression and prognosis. In most solid tumours, a biopsy is challenging, costly, painful or potentially risky for the patient. Therefore, non-invasive methods like 'liquid biopsy' for analysis of histone modifications and their modifiers if possible will be helpful in the better clinical management of cancer patients. METHODS: Here, we have developed a cost-effective and time-efficient protocol for isolation of circulating histones from serum of solid tumor, HCC, called Dual Acid Extraction (DAE) protocol and have confirmed by mass spectrometry. Also, we measured the activity of HDACs and HATs in serum samples. RESULTS: The serum purified histones were profiled for changes in histone PTMs and have shown a comparable pattern of modifications like acetylation (H4K16Ac), methylation (H4K20Me3, H3K27Me3, H3K9Me3) and phosphorylation (γ-H2AX and H3S10P) to paired cancer tissues. Profiling for the histone PTM changes in various other organs of normal and tumor bearing animal suggests that the changes in the histone PTMs observed in the tumor serum is indeed due to changes in the tumor tissue only. Further, we demonstrate that the observed hypo-acetylation of histone H4 in tissue and serum samples of tumor bearing animals corroborated with the elevated HDAC activity in both samples compared to normal. Interestingly, human normal and tumor serum samples also showed elevated HDAC activity with no significant changes in HAT activity. CONCLUSIONS: Our study provides the first evidence in the context of histone PTMs and modifiers that liquid biopsy is a valuable predictive tool for monitoring disease progression. Importantly, with the advent of drugs that target specific enzymes involved in the epigenetic regulation of gene expression, liquid biopsy-based 'real time' monitoring will be useful for subgrouping of the patients for epi-drug treatment, predicting response to therapy, early relapse and prognosis.

Brief Communication: Featured Article: Histone H2A mono-ubiquitination and cellular transformation are inversely related in N-nitrosodiethylamine-induced hepatocellular carcinoma.

Aberrant changes in histone post-translational modifications are encountered frequently in diseases like cancer. Although histone H3 post-translational modifications have been extensively studied in context of diseases, the functionally important histone H2A PTM H2A119ub (H2Aub) has not gained much attention. In this study, we report that H2Aub markedly decreases in hepatocellular carcinoma. Usp21, a H2A deubiquitinase, is probably responsible for decrease in H2Aub. In addition, the H2Aub levels showed an inverse correlation with H3S10 phosphorylation (H3S10p) and the proliferative state of the cells. Downregulation of H2Aub is also associated with increased expression of growth factor gene lipocalin 2. Interestingly, we show that treatment of cells with histone deacetylase inhibitor trichostatin A results in increase of H2Aub and decrease in H3S10p. Our work for the first time suggests the in vivo association of H3S10p, H4ac, and H2A119ub with cellular transformation.

p38-MAPK/MSK1-mediated overexpression of histone H3 serine 10 phosphorylation defines distance-dependent prognostic value of negative resection margin in gastric cancer.

BACKGROUND: Alterations in histone modifications are now well known to result in epigenetic heterogeneity in tumor tissues; however, their prognostic value and association with resection margins still remain poorly understood and controversial. Further, histopathologically negative resection margins in several cancers have been associated with better prognosis of the disease. However, in gastric cancer, despite a high rate of R0 resection, a considerably high incidence of loco-regional recurrence is observed. We believe alterations of global histone post-translational modifications could help in identifying molecular signatures for defining the true negative surgical resection margins and also the prognosis of gastric cancer patients. RESULTS: The present study compares the level of H3S10ph among paired tumor and histopathologically confirmed disease-free (R0) proximal and distal surgical resection margin (PRM and DRM) tissue samples of GC patients (n = 101). Immunoblotting and immune-histochemical analysis showed a significantly (p < 0.01) higher level of H3S10ph in tumor compared to R0 surgical resection margins. Along with tumor, high H3S10ph levels in both PRM and DRM correlated with clinical parameters and poor survival. Interestingly, in the case of PRM and DRM, the association of H3S10ph with poor survival was only found in a patient group with the resection margin distance <4 cm. Further investigations revealed that the increase of H3S10ph in tumor tissues is not due to the change in cell cycle profile but rather an interphase-associated phenomenon. Moreover, an increase in ph-MSK1 and ph-p38 levels in tumor tissues and the decrease in ph-MSK1 and H3S10ph on p38 inhibition in gastric cancer cells confirmed p38-MAPK/MSK1 pathway-mediated regulation of H3S10ph in gastric cancer. CONCLUSIONS: Our study provides the first evidence that p38-MAPK/MSK1-regulated increase of H3S10ph in GC is predictive of a more aggressive cancer phenotype and could help in defining true negative surgical resection margin. Importantly, our data also gave a new rationale for exploration of the use of MSK1 inhibitor in gastric cancer therapy and the combination of histone post-translational modifications, H4K16ac and H4K20me3 along with H3S10ph as epigenetic prognostic markers.

Techniques to access histone modifications and variants in cancer.

Recent years have witnessed an explosion of epigenetic research on the role of histone variants and modifications in cancer. To understand the global dynamics of chromatin structure and function, analysis of histone variants incorporated into the nucleosome and their covalent modifications, is required. The nucleosome is the fundamental structural unit of chromatin, contains an octamer of core histones H3, H4, H2A, and H2B. The differential alterations in diverse histone variants and their accompanying modifications patterns will provide a deeper insight into their biological role in structural and functional properties of chromatin. Here we provide a step-by-step protocol to investigate these aspects, the histone modifications and variants, their localization and dynamics within specific regions of chromatin under distinct condition and the recruitment/retention of epigenetic regulators at their target sites in chromatin to influence cell growth and differentiation.

Dynamic alteration in H3 serine 10 phosphorylation is G1-phase specific during ionization radiation induced DNA damage response in human cells.

Chromatin acts as a natural barrier in DNA-damage recognition and repair. Histones undergo differential post-translational modification(s) to facilitate DNA damage response (DDR). Importance of modifications like phosphorylation of histone variant H2A.X in DNA repair is very well understood, however, ambiguous results exist in literature regarding the levels of certain histone modifications and their possible role in repair. In the present study, we have investigated in depth the alteration in the level of the highly dynamic histone mark H3S10P as it plays a dual role in different phases of the cell cycle. We show here that H3S10P decreases specifically from irradiated G1-enriched cells irrespective of the damaging agent or the cell line used in the study. Interestingly, the loss occurs predominantly from H3.3 variant which is a transcription activation mark like H3S10P itself, suggesting that the alteration might be implicated in transcription repression. The decrease in other transcription marks like H3K9Ac, H3K14Ac, H3K56Ac and H3S28P along with the occurrence of chromatin condensation in response to DNA damage in G1 phase strengthens the hypothesis. In addition, the alteration in the level of H3S10P shows an inverse correlation with that of γH2AX in a dose-dependent manner and probably occurs from the same mononucleosome. We propose that the drop in the levels of histone H3S10 phosphorylation is a universal phenomenon in response to DNA damage and is a trigger to induce transcription repressive state to facilitate repair.

Expression of histone variant, H2A.1 is associated with the undifferentiated state of hepatocyte.

Recent studies suggest the incorporation of histone variants into the chromatin regulate cellular proliferation, differentiation, and de-differentiation. We have earlier reported the increase of H2A.1 variant during sequential de-differentiation of hepatocyte to hepato-cellular carcinoma. Here, we decipher the alterations in expression of H2A.1 and H2A.2 variants during rat liver embryogenesis and regeneration. The expression of H2A.1 and H2A.2, at protein and mRNA level, does not alter in normal cellular proliferation associated with regeneration of liver post PH. In contrast, gradual decrease of H2A.1 with increase of H2A.2 is observed during differentiation of embryonic to adult liver. Furthermore, the accumulation of H2A.1 is higher in embryonic stem cells compared to normal adult liver. Collectively, these data support a strong correlation of H2A.1 expression with undifferentiated cells and overall epigenetic reprogramming in dedifferentiation and maturation of undifferentiated cells, rather than with normal cellular proliferation.

Chemopreventive and hepatoprotective effects of embelin on N-nitrosodiethylamine and carbon tetrachloride induced preneoplasia and toxicity in rat liver.

Embelin, an active constituent isolated from the fruits of Embelia tsjeriam cottam was investigated for its chemopreventive and hepatoprotective effects against N-nitrosodiethylamine (NDEA) induced liver preneoplasia or carbon tetrachloride (CCl4) induced liver damage. Rats received NDEA, 1 ppm/g b.w. in drinking water for 6 weeks or CCl4, 0.7 ml/kg i.p. once a week for 4 weeks and embelin 50 mg, 100 mg/kg b.w. orally prior, during and after exposure to NDEA/CCl4 for 20 or 5 weeks, respectively. Embelin treatment significantly prevented NDEA or CCl4 induced increase in biochemical marker enzymes: glutamate pyruvate transaminase, glutamate oxaloacetate transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, glutathione-S-transferase, lipid peroxidase as well as hypoproteinemia, hypoalbuminuria and glutathione depletion. This was further substantiated by marked decrease in incidence of preneoplastic foci, and inflammatory cells on histopathological and transmission electron microscopic analysis. The present study suggests embelin is a promising chemopreventive and hepatoprotective agent.

Sida rhombifolia ssp. retusa seed extract inhibits DEN induced murine hepatic preneoplasia and carbon tetrachloride hepatotoxicity.

Sida rhombifolia ssp. retusa is a well established drug in the Ayurvedic system of medicine used for antirheumatism and antiasthmatism. Inhibitory effects of S. rhombifolia ssp. retusa seed extract on DEN induced hepatocellular preneoplastic foci and carbon tetrachloride (CCl4) induced hepatotoxicity was investigated in rats. Rats received DEN, 1ppm/g b.w. in drinking water for 6 weeks or CCl(4), 0.7 ml/kg i.p. once a week for 4 weeks and seed extract 50 mg, 100 mg/kg b.w. orally prior, during and after exposure to DEN/CCl4 for 20 or 5 weeks, respectively. Treatment with seed extract significantly inhibited the increase in DEN/CCl(4) induced activities of pre-cancerous marker enzymes; gamma-glutamyl transpeptidase, glutathione-S-transferase, hepatotoxicity marker enzymes; glutamate pyruvate transaminase, glutamate oxaloacetate transaminase and alkaline phosphatase as well as lipid peroxidase. Depleted glutathione, protein and albumin levels were restored. Also, histopathological and transmission electron microscopic studies showed prevention of cellular degenerative changes. The chemopreventive and hepatoprotective potentials of seed extract are due to free radical scavenging activity and restoration of cellular structural integrity.