Ovarian cancer is 1 of the most significant malignancies in the Western world, and the antiangiogenesis strategy has been postulated for prevention and treatment of ovarian cancers. Kaempferol is a natural flavonoid present in many fruits and vegetables. The antiangiogenesis potential of kaempferol and its underlying mechanisms were investigated in two ovarian cancer cell lines, OVCAR-3 and A2780/CP70. Kaempferol mildly inhibits cell viability but significantly reduces VEGF gene expression at mRNA and protein levels in both ovarian cancer cell lines. In chorioallantoic membranes of chicken embryos, kaempferol significantly inhibits OVCAR-3-induced angiogenesis and tumor growth. HIF-1α, a regulator of VEGF, is downregulated by kaempferol treatment in both ovarian cancer cell lines. Kaempferol also represses AKT phosphorylation dose dependently at 5 to 20 μM concentrations. ESRRA is a HIF-independent VEGF regulator, and it is also downregulated by kaempferol in a dose-dependent manner. Overall, this study demonstrated that kaempferol is low in cytotoxicity but inhibits angiogenesis and VEGF expression in human ovarian cancer cells through both HIF-dependent (Akt/HIF) and HIF-independent (ESRRA) pathways and deserves further studies for possible application in angio prevention and treatment of ovarian cancers.

BackgroundOvarian cancer is one of the most significant malignancies in the western world. Studies showed that Ovarian cancers tend to grow resistance to cisplatin treatment. Therefore, new approaches are needed in ovarian cancer treatment. Kaempferol is a dietary flavonoid that is widely distributed in fruits and vegetables, and epidemiology studies have revealed a protective effect of kaempferol against ovarian cancer risk. Our early studies also found that kaempferol is effective in reducing vascular endothelial growth factor (VEGF) expression in ovarian cancer cells. In this study, we investigated kaempferol's effects on sensitizing ovarian cancer cell growth in response to cisplatin treatment.ResultsTen chemicals were screened for sensitizing OVCAR-3 ovarian cancer cell growth in response to cisplatin treatment. For kaempferol, which shows a significant synergistic interaction with cisplatin, expression of ABCC1, ABCC5, ABCC6, NFkB1, cMyc, and CDKN1A genes was further examined. For cisplatin/kaempferol treatments on OVCAR-3 cancer cells, the mRNA levels of ABCC1, ABCC5, and NFkB1 did not change. However, significant inhibition of ABCC6 and cMyc mRNA levels was observed for the cisplatin/kaempferol combined treatment. The CDKN1A mRNA levels were significantly up-regulated by cisplatin/kaempferol treatment. A plot of CDKN1A mRNA levels against that of cMyc gene further revealed a reverse, linear relationship, proving cMyc's regulation on CDKN1A gene expressions. Our work found that kaempferol works synergistically with cisplatin in inhibiting ovarian cancer cell viability, and their inhibition on cell viabilities was induced through inhibiting ABCC6 and cMyc gene transcription. Apoptosis assay showed the addition of 20 μM kaempferol to the cisplatin treatment induces the apoptosis of the cancer cells.ConclusionsKaempferol enhances the effect of cisplatin through down regulation of cMyc in promoting apoptosis of ovarian cancer cells. As a dietary component, kaempferol sensitizes ovarian cancer cells to cisplatin treatment and deserves further studies for possible applications in chemotherapy of ovarian cancers.

Cell size is specific to each species and impacts cell function. Various phenomenological models for cell size regulation have been proposed, but recent work in bacteria has suggested an 'adder' model, in which a cell increments its size by a constant amount between each division. However, the coupling between cell size, shape and constriction remains poorly understood. Here, we investigate size control and the cell cycle dependence of bacterial growth using multigenerational cell growth and shape data for single Caulobacter crescentus cells. Our analysis reveals a biphasic mode of growth: a relative timer phase before constriction where cell growth is correlated to its initial size, followed by a pure adder phase during constriction. Cell wall labelling measurements reinforce this biphasic model, in which a crossover from uniform lateral growth to localized septal growth is observed. We present a mathematical model that quantitatively explains this biphasic 'mixer' model for cell size control.

Fluorescence recovery after photobleaching (FRAP) is widely used to interrogate diffusion and binding of proteins in live cells. Herein, we apply two-photon excited FRAP with a diffraction limited bleaching and observation volume to study anomalous diffusion of unconjugated green fluorescence protein (GFP) in vitro and in cells. Experiments performed on dilute solutions of GFP reveal that reversible fluorophore bleaching can be mistakenly interpreted as anomalous diffusion. We derive a reaction-diffusion FRAP model that includes reversible photobleaching, and demonstrate that it properly accounts for these photophysics. We then apply this model to investigate the diffusion of GFP in HeLa cells and polytene cells of Drosophila larval salivary glands. GFP exhibits anomalous diffusion in the cytoplasm of both cell types and in HeLa nuclei. Polytene nuclei contain optically resolvable chromosomes, permitting FRAP experiments that focus separately on chromosomal or interchrosomal regions. We find that GFP exhibits anomalous diffusion in chromosomal regions but diffuses normally in regions devoid of chromatin. This observation indicates that obstructed transport through chromatin and not crowding by macromolecules is a source of anomalous diffusion in polytene nuclei. This behavior is likely true in other cells, so it will be important to account for this type of transport physics and for reversible photobleaching to properly interpret future FRAP experiments on DNA-binding proteins.

1 Cell size is specific to each species and impacts their ability to function. While 1 various phenomenological models for cell size regulation have been proposed, recent 2 work in bacteria have demonstrated an adder mechanism, in which a cell increments 3 its size by a constant amount between each division. However, the coupling between 4 cell size, shape and constriction, remain poorly understood. Here, we investigate size 5 control and the cell cycle dependence of bacterial growth, using multigenerational cell 6 growth and shape data for single Caulobacter crescentus cells. Our analysis reveals 7 a biphasic growth mechanism: a relative timer phase before constriction where cell 8 growth is correlated to its initial size, followed by a pure adder phase during constric-9 tion. Cell wall labeling measurements reinforce this biphasic behavior: a crossover 10 from uniform lateral growth to localized septal growth is observed. We develop a 11 mathematical model that quantitatively explains this mixer mechanism for size con-12 trol. 13 14 We recently introduced a technology that enables obtaining unprecedented amounts of precise 15 quantitative information about the shapes of single bacteria as they grow and divide under non-16 crowding and controllable environmental conditions [1, 2]. Others have developed complementary 17 methods [3-6]. These single-cell studies are generating great interest because they reveal unantic-18 ipated relationships between cell size and division control [5]. Recent work in bacteria that utilize 19 these technologies revealed that a constant size increment between successive generations [7] quan-20 titatively describes the strategy for bacterial size maintenance in E. coli [3-5], B. subtilis [5], C. 21 crescentus [4], P. aeruginosa [8] and even in the yeast S. cerevisiae [9]. This phenomenological ob-22 servation has been termed an adder model for cell size control. Competing models for size control 23 include cell division at a critical size (sizer model) [10] or at a constant interdivision time (timer 24 model) [1]. Analysis of single-cell data show that cell size at division is positively correlated with 25the cell size at birth [1, 4, 5, 11, 12], thus precluding a sizer model. In addition, a negative corre-26 lation between initial cell size and interdivision times, as reported here and in refs [1, 4, 5, 12, 13], 27 is inconsistent with the timer model. However, other studies have suggested mixed models of 28 size control, with diverse combinations of sizer, timer and adder mechanisms [14][15][16][17]. The spatial 29 resolution and statistically large size of our data now allow us to revisit these issues with greater 30 precision. 31While cell size serves as an important determinant of growth, the bacterial cell cycle is composed 32 of various coupled processes including DNA replication and cell wall constriction that have to be 33 2 faithfully coordinated for cells to successfully divide [18]. This raises the question of what other 34 cell cycle variables regulate growth and how the ...