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DNA double-strand breaks are critical lesions that can lead to chromosomal aberrations and genomic instability. In response to DNA damage, Chk1, a serine/threonine kinase, is responsible for cell cycle arrest to prevent damaged cells from progressing through the cell cycle. Here, we report that the disruption of wat1, a WD repeat-containing protein, leads to the phosphorylation of Chk1. The double-deletion of chk1 and wat1 had a grave effect on the survival of fission yeast cells, and the spontaneous recombination rate was also high upon double-deletion of wat1 and chk1, as compared to the single-mutant. In the absence of wat1, the cells exhibited a high level of nuclear fragmentation that resulted in the accumulation of Rad22 yellow fluorescent protein foci. Furthermore, we show that wat1 is required for the regulation of the oxidative stress response. We observed elevated levels of reactive oxygen species (ROS) generation in wat1-null mutant that led to a high degree of propidium iodide staining at nonpermissive temperature. Based on the results presented here, we hypothesize that ROS production in wat1-null mutant cells generates DNA fragmentation that could trigger a checkpoint response and that, in the absence of checkpoint kinase Chk1, the cells exhibit severe growth defects leading to a synthetic lethal phenotype. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cervical cancer is the most prevalent cancer in females. Melatonin, a neurohormone has been documented as a promising therapeutic molecule for cervical cancer. However, the underlying molecular mechanism is not known. We explored the dose-dependent anti-tumor response of melatonin against cervical cancer cell lines, HeLa (HPV-18 positive) and SiHa (HPV-16 positive). The anti-cancer effect of melatonin was evaluated by MTT assay, cell imaging, colony formation, DAPI, AO/PI, LDH, Flow cytometry, scratch assay, western blot analysis and real-time PCR. Results of DAPI, AO/PI, LDH, and Annexin/PI staining revealed that melatonin induces apoptosis. The results of cell cycle analysis revealed that melatonin arrests the HeLa and SiHa cells in sub-G1 and G1 phases, respectively. Western blot analysis revealed that melatonin downregulated the expression of pro-inflammatory transcription factor, NF-κB and the expression of COX-2 protein, a key mediator in cell proliferation. In addition, melatonin downregulated the expression of an invasive marker, MMP-9, an antiapoptotic protein, Bcl-2, and upregulated the expression of pro-apoptotic protein, Bax at both transcriptional and translational levels. Overall, the results suggest that melatonin exhibited strong anti-cancer therapeutic potential against human cervical cancer cell line progression possibly through inhibition of NF-κB signalling pathway. [ABSTRACT FROM AUTHOR]

Traditional medicinal plants have gained attention as a potential therapeutic agent to combat cancer and inflammation. Diosgenin rich fresh extracts of Paris polyphylla rhizome from Indian Himalaya is traditionally used as wound healing, anti-bleeding, anti-inflammatory and anti-cancer agent by the folk healers. Present study was aimed to prepare two types of extracts from Paris polyphylla rhizome of Indian Himalayan landraces – 1. ethanolic extract of Paris polyphylla rhizome (EEPPR) and 2. Diosgenin enriched Paris polyphylla rhizome extract (DPPE), quantification of diosgenin content, and to evaluate their in vitro anti-oxidant, in vivo anti-inflammatory and in vitro cytotoxicity and anti-cancer activities of the DPPE. Diosgenin content of EEPPR was quantified through GC-MS while diosgenin content of DPPE was quantified through HPTLC, and the diosgenin yield from EEPPR and DPPE were compared. In vitro antioxidant activities of DPPE were performed using DPPH, NOD, RP and SOD assay while in vivo anti-inflammatory activity of DPPE were evaluated in dextran induced hind paw edema in rats. In vitro cytotoxicity and anti-cancer activities of DPPE were evaluated in human breast cancer cell lines (MCF-7, MDA-MB-231), cervical cancer cell lines (HeLa) and Hep-2 cell lines. EEPPR obtained through cold extraction method using 70% ethanol showed maximum diosgenin content of 17.90% quantified through GC-MS while similar compounds pennogenin (3.29%), 7β-Dehydrodiosgenin (1.90%), 7-Ketodiosgenin acetate (1.14%), and 7 β-hydroxydiosgenin (0.55%) were detected in low concentration, and thus confirmed diosgenin as major and lead phytochemical. However, DPPE obtained through both cold and repeated hot extraction with the same solvent (70% ethanol) showed diosgenin content of 60.29% which is significantly higher (p < 0.001) than the diosgenin content in EEPPR. DPPE demonstrated significant in vitro antioxidant activities by dose-dependently quenched (p < 0.001) SOD free radicals by 76.66%, followed by DPPH (71.43%), NOD (67.35%), and RP (63.74%) at a max concentration of 2 μg/μl of ascorbic acid and test drugs with remarkable IC 50 values (p < 0.01). Further, DPPE also showed potent anti-inflammatory activities by dose-dependently suppressed dextran induced paw edema in rats (p < 0.01) from 2 h to 4 h. DPPE suppressed the proliferation of MCF-7, MDA-MB-231, Hep-2 and HeLa cell lines. Maximum activity was observed in MCF-7 cells. The DPPE also induced apoptosis in MCF-7 cell lines as measured by AO/PI and DAPI staining, as well as DNA laddering, cell cycle analysis and phosphatidylserine externalization assay. The growth-inhibitory effect of DPPE on MCF-7 breast cancer cells was further confirmed from the colony-formation assay. DPPE upregulated expression of Bax and downregulated Bcl-2 and survivin mRNA transcripts. DPPE obtained through both cold and repeated hot extraction using ethanol showed significantly higher content of diosgenin than the diosgenin content detected in EEPPR. However, diosgenin yield of both the extracts (EEPPR & DPPE) clearly confirmed diosgenin as major and lead phytochemical of Paris polyphylla rhizome of Indian Himalayan landraces. Further, DPPE also demonstrated potent in vitro anti-oxidative and in vivo anti-inflammatory activities and showed in vitro cytotoxicity and significant anti-cancer (apoptosis) effects in MCF-7 breast cancer cells. Image 1 • GC-MS study of EEPPR confirmed diosgenin (17.90%) as lead phytochemical in Paris polyphylla landraces of Indian Himalaya. • HPTLC study of Diosgenin enriched Paris polyphylla rhizome extract (DPPE) reveals higher diosgenin content (60.29%). • DPPE possess significant in vitro anti-oxidant and in vivo anti-inflammatory activities. • DPPE showed cytotoxicity and anti-cancer activities in MCF-7, MDA-MB-231, Hep-2 and HeLa cell lines. • DPPE showed significant anti-cancer (apoptosis) effects in MCF-7 breast cancer cells. [ABSTRACT FROM AUTHOR]