Molecular basis for the pharmacological activities of piperlongumine against breast cancer: Role of glucose import, ROS, NF-κB and lncRNAs

Background: Piperlongumine (PL, piplartine) is an alkaloid derived from the Piper longum L. (long pepper) root. The activities PL against breast cancer and the underlying mechanism is not thoroughly investigated. Aim: We examined the anti-cancer activities of PL against breast cancer cells. The molecular basis for the pharmacological activities of this alkaloid was also examined. Methods: The breast cancer cell lines such as MCF-7, T-47D, MDA-MB-231, MDA-MB-468 and MDA-MB-453 were used during the study. We used MTT assay, clonogenic and soft agar colony formation assay for cytotoxicity. The cell cycle analysis, phosphatidylserine externalization assay, measurement of mitochondrial membrane potential, AO/PI and DAPI staining, and DNA laddering was used for apoptosis. The western blot analysis was performed to examine the expression pattern of tumorigenic proteins. Other parameters used were the intracellular detection of ROS, immunocytochemistry for NF-κB and GLUT-1 activation, wound healing assay for cell migration, and real-time PCR for lncRNA expression. We also evaluated if PL can enhance the efficacy of doxorubicin in swiss albino mice implanted with Ehrlich Ascites Carcinoma (EAC) cells and metabolic parameters were also examined in serum of mice. Results: PL inhibited proliferation and suppressed the long-term as well as soft agar colony formation of breast cancer cells in a dose dependent manner. PL induced ROS generation and accumulation of cells in sub-G1 phase, mitochondria mediated apoptosis in cancer cells as revealed by the presence of fragmented nuclei, PARP activation, loss of mitochondrial membrane potential, chromatin condensation, DNA laddering and suppression in the expression of cell survival proteins. PL reduced glucose import and modifies the expression of glucose and lactate transporter in breast cancer cells. The amide alkaloid suppresses the TNF-α induced NF-κB activation and modulate the lncRNAs such as MEG-3, GAS-5 and H19 expression in breast cancer. In mice model, PL was found to synergize with doxorubicin by reducing the size, volume and weight of the tumor. With an increase in the concentration of PL, the serum cholesterol and triglyceride levels were decreased while there was increase in the serum level of glucose in EAC bearing mice. Conclusion: PL exhibit potential against breast cancer. Further, PL enhances the efficacy of doxorubicin in EAC mice model. The modulation of lncRNAs, NF-κB and glucose import may contribute to the activities of PL against breast cancer

Quasiperiodic ordering in thick Sn layer on ii-Al-Pd-Mn: A possible quasicrystalline clathrate

Realization of an elemental solid-state quasicrystal has remained a distant dream so far in spite of extensive work in this direction for almost two decades. Here, we report the discovery of quasiperiodic ordering in a thick layer of elemental Sn grown on icosahedral ($i$)-Al-Pd-Mn. The STM images and the LEED patterns of the Sn layer show specific structural signatures that portray quasiperiodicity but are distinct from the substrate. Photoemission spectroscopy reveals the existence of the pseudogap around the Fermi energy up to the maximal Sn thickness. The structure of the Sn layer is modeled as a novel form of quasicrystalline clathrate on the basis of the following: Firstly, from ab-initio theory, the energy of bulk Sn clathrate quasicrystal is lower than the high temperature metallic $\beta$-Sn phase, but higher than the low temperature $\alpha$-Sn phase. A comparative study of the free slab energetics shows that surface energy favors clathrate over $\alpha$-Sn up to about 4 nm layer thickness, and matches $\beta$-Sn for narrow window of slab thickness of 2-3 nm. Secondly, the bulk clathrate exhibits gap opening near Fermi energy, while the free slab form exhibits a pronouced pseudogap, which explains the pseudogap observed in photoemission. Thirdly, the STM images exhibit good agreement with clathrate model. We establish the adlayer-substrate compatibility based on very similar (within 1%) the cage-cage separation in the Sn clathrate and the pseudo-Mackay cluster-cluster separation on the $i$-Al-Pd-Mn surface. Furthermore, the nucleation centers of the Sn adlayer on the substrate are identified and these are shown to be a valid part of the Sn clathrate structure. Thus, based on both experiment and theory, we propose that 4 nm thick Sn adlayer deposited on 5-fold surface of $i$-Al-Pd-Mn substrate is in fact a metastable realization of elemental, clathrate family quasicrystal.Comment: 10 figures in the Manuscript and the 8 figures in the Supplementary materia

Isodeoxyelephantopin, a Sesquiterpene Lactone Induces ROS Generation, Suppresses NF-κB Activation, Modulates LncRNA Expression and Exhibit Activities Against Breast Cancer

The sesquiterpene lactones, Isodeoxyelephantopin (IDET) and Deoxyelephantopin (DET) are known to exhibit activities against some cancer types. The activities of these lactones against breast cancer and the molecular bases is not known. We examined the efficacy of lactones in breast cancer preclinical model. Although both lactones exhibited drug like properties, IDET was relatively effective in comparison to DET. IDET suppressed the proliferation of both invasive and non-invasive breast cancer cell lines. IDET also suppressed the colony formation and migration of breast cancer cells. The assays for Acridine Orange (AO)/Propidium Iodide (PI) staining, cell cycle distribution, phosphatidylserine externalization and DNA laddering suggested the apoptosis inducing potential of IDET. The treatment with IDET also induced an accumulation of cells in the sub-G1 and G2/M phases. The exposure of breast cancer cells to the lactone was associated with a depolarization in mitochondrial membrane potential, and cleavage of caspase and PARP. The lactone induced reactive oxygen species (ROS) generation in breast cancer cells. Further, the use of N-acetyl cysteine (NAC) suppressed IDET induced ROS generation and apoptosis. The NF-κB-p65 nuclear translocation induced by okadaic acid (OA) was suppressed by the sesquiterpene. IDET also suppressed the expression of NF-κB regulated tumorigenic proteins, and induced the expression of proapoptotic gene (Bax) in cancer cells. While the expression of oncogenic lncRNAs was suppressed, the tumor suppressor lncRNAs were induced by the sesquiterpene. Collectively, the modulation of multiple cell signaling molecules by IDET may contribute to its activities in breast cancer cells

Targeting IκappaB kinases for cancer therapy

The inhibitory kappa B kinases (IKKs) and IKK related kinases are crucial regulators of the pro-inflammatory transcription factor, nuclear factor kappa B (NF-κB). The dysregulation in the activities of these kinases has been reported in several cancer types. These kinases are known to regulate survival, proliferation, invasion, angiogenesis, and metastasis of cancer cells. Thus, IKK and IKK related kinases have emerged as an attractive target for the development of cancer therapeutics. Several IKK inhibitors have been developed, few of which have advanced to the clinic. These inhibitors target IKK either directly or indirectly by modulating the activities of other signaling molecules. Some inhibitors suppress IKK activity by disrupting the protein-protein interaction in the IKK complex. The inhibition of IKK has also been shown to enhance the efficacy of conventional chemotherapeutic agents. Because IKK and NF-κB are the key components of innate immunity, suppressing IKK is associated with the risk of immune suppression. Furthermore, IKK inhibitors may hit other signaling molecules and thus may produce off-target effects. Recent studies suggest that multiple cytoplasmic and nuclear proteins distinct from NF-κB and inhibitory κB are also substrates of IKK. In this review, we discuss the utility of IKK inhibitors for cancer therapy. The limitations associated with the intervention of IKK are also discussed

Reconstructing the demographic history of the Himalayan and adjoining populations

The rugged topography of the Himalayan region has hindered large-scale human migrations, population admixture and assimilation. Such complexity in geographical structure might have facilitated the existence of several small isolated communities in this region. We have genotyped about 850,000 autosomal markers among 35 individuals belonging to the four major populations inhabiting the Himalaya and adjoining regions. In addition, we have genotyped 794 individuals belonging to 16 ethnic groups from the same region, for uniparental (mitochondrial and Y chromosomal DNA) markers. Our results in the light of various statistical analyses suggest a closer link of the Himalayan and adjoining populations to East Asia than their immediate geographical neighbours in South Asia. Allele frequency-based analyses likely support the existence of a specific ancestry component in the Himalayan and adjoining populations. The admixture time estimate suggests a recent westward migration of populations living to the East of the Himalaya. Furthermore, the uniparental marker analysis among the Himalayan and adjoining populations reveal the presence of East, Southeast and South Asian genetic signatures. Interestingly, we observed an antagonistic association of Y chromosomal haplogroups O3 and D clines with the longitudinal distance. Thus, we summarise that studying the Himalayan and adjoining populations is essential for a comprehensive reconstruction of the human evolutionary and ethnolinguistic history of eastern Eurasia