Characterization of bioenergetic and kinematic plasticity of bovine sperm reveals novel and dynamic temporal traits

Sperm transport through the female reproductive tract requires energy for motility and fertilization. Sperm kinematic assessment is conducted as an industry standard to estimate semen quality prior to bovine insemination. However, individual samples with similar post-thaw motility result in different pregnancy outcomes, suggesting that differences in bioenergetics may be important for sperm function. Thus, characterization of bioenergetic and kinematic parameters of sperm over time may reveal novel metabolic requirements for sperm function. Post-thawed sperm from five samples of individual (A, B, C) and pooled bulls (AB, AC) were assessed at 0 and 24 hr after thawing. Sperm were evaluated for kinematics via Computer-Assisted Sperm Analyses and bioenergetic profiles using a Seahorse Analyzer for basal respiration [BR], mitochondrial stress test [MST] and energy map [EM]. Motility was nearly identical among samples after thawing and no differences in bioenergetics were detected. However, after 24 hr of sperm storage, pooled sperm samples (AC) presented with higher BR and proton leakage compared to other samples. Sperm kinematic variability among samples was higher after 24 hr, suggesting difference in sperm quality may manifest over time. Despite a reduction in motility and mitochondrial membrane potential, BR was higher at 24 hr compared to 0 hr for nearly all samples. A metabolic divergence between samples was detected by EM, indicating a shift in bioenergetic profiles over time that was undetected after thawing. These new bioenergetic profiles elucidate a novel dynamic plasticity of sperm metabolism over time while suggesting an influence of heterospermic interactions for further investigation.

Abstract 131: Anti-inflammatory and Mitochondrial Effects of Butyrate in Shr Astrocytes in vitro

Emerging evidence demonstrates a significant link between gut dysbiosis and hypertension (HTN). Butyrate is one of the major fermented end-products of gut microbiota that reportedly produces beneficial effects on the immune system and metabolism. A contraction in butyrate-producing bacteria in the gut of spontaneously hypertensive rats (SHR) suggests that reduced butyrate may be associated with HTN. Considering its role in mitochondrial metabolism, we proposed that the positive anti-inflammatory effects of butyrate may be mediated via improvement in mitochondrial function in astrocytes.

Methods: Sprague Dawley (SD) and SHR primary astrocytes from two-day old pups were cultured in DMEM, supplemented with 10% FBS and 1% pen/strep, for 14 days, prior to treatment with butyrate (0-1mM) for 4 hours. Cells were then subjected to the Seahorse XFe24 Extracellular Flux Analyzer to evaluate mitochondrial function following butyrate treatment. Additional samples were collected for total RNA isolation for real time PCR analysis of inflammatory factors and transcripts related to mitochondrial function and stress.

Results: Butyrate significantly increased both basal and maximal mitochondrial respiration (by 3-4 fold, P<0.001) and elevated proton leak (by 4 fold, P<0.01) in astrocytes from SD rats but not SHR. Furthermore, we observed a trend for an increase in both ATP-linked and non-mitochondrial respiration in SD astrocytes compared to SHR (by 2-3 fold, P=0.07). This was associated with a significant reduction in relative expression levels in catalase (by 50%, P<0.05) and a trend in reduction in Sod1 and Sod2 (by 25%-50%, P=0.1) in astrocytes harvested from SD rats but not the SHR. Conversely, butyrate significantly lowered expression of pro-inflammatory Ccl2 (by 33%, P<0.05) and Tlr4 (by 48%, P <0.05) in astrocytes of SHR, but not SD rats.

Conclusion: Butyrate modulated mitochondrial bioenergetics in SD but not the SHR, suggesting that the mitochondria of astrocytes may be less sensitive to the effects of butyrate in HTN. In addition, butyrate reduced inflammatory mediators in the SHR, but had no effect in the SD rat astrocytes. Thus, central anti-inflammatory effects of butyrate may be mediated via a mitochondria-independent mechanism.

Abstract TMEM-034: THE HEAT SHOCK TRANSCRIPTION FACTOR HSF1 INDUCES OVARIAN CANCER EPITHELIAL-MESENCHYMAL TRANSITION IN A 3D SPHEROID GROWTH MODEL

Ovarian cancer is the most lethal gynecological cancer, with over 200,000 women diagnosed each year and over half of those cases leading to death. These poor statistics are related to a lack of early symptoms and inadequate screening techniques. This results in the cancer going undetected until later stages when the tumor has metastasized through a process that requires the epithelial to mesenchymal transition (EMT). In lieu of traditional monolayer cell culture, EMT and cancer progression in general is best characterized through the use of 3D spheroid models. Compared to other cancers, ovarian cancer has very limited treatment options to date, with cisplatin and paclitaxel being the most common and efficient. Recently, a significant increase in heat shock factor 1 (HSF1) expression has been found in highly malignant ovarian cancer. HSF1 is the regulator of the heat shock response (HSR) and promotes the transcription of heat shock proteins (HSPs). Previous studies have shown that HSF1-induced chaperone activity may act to stabilize multiple oncogenes within many different cancer types. This leads to cancer proliferation, reduced apoptosis, and metastasis. In this study, we examine gene expression changes through microarray analysis in spheroid versus monolayer ovarian cancer cells treated with TGFβ to induce EMT. Interestingly, EMT and stress response pathways, including the heat shock response, were all significantly affected by 3D growth. HSF1 knockdown was utilized in both 2D and 3D cultures to further study this response. HSF1 knockdown is shown to inhibit ovarian cancer progression in both monolayer and spheroid model cells. Moreover, HSF1 knockdown in spheroid cells has a significantly greater impact on EMT markers than it does in 2D cultures. This indicates HSF1 may be a utilized as a target for chemotherapeutics in ovarian cancer patients and could potentially have implications in other such hormonal cancers.

Citation Format: Trillitye Paullin, Chase Powell, Chris Menzie, Robert Hill, Christopher Martyniuk, and Sandy D. Westerheide. THE HEAT SHOCK TRANSCRIPTION FACTOR HSF1 INDUCES OVARIAN CANCER EPITHELIAL-MESENCHYMAL TRANSITION IN A 3D SPHEROID GROWTH MODEL [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr TMEM-034.

Abstract A41: The heat shock transcription factor HSF1 induces ovarian cancer epithelial-mesenchymal transition in a 3-D spheroid growth model

Ovarian cancer is the most lethal gynecological cancer, with over 200,000 women diagnosed each year and over half of those cases leading to death. These poor statistics are related to a lack of early symptoms and inadequate screening techniques. This results in the cancer going undetected until later stages when the tumor has metastasized through a process that requires the epithelial to mesenchymal transition (EMT). In lieu of traditional monolayer cell culture, EMT and cancer progression in general is best characterized through the use of 3D spheroid models. Compared to other cancers, ovarian cancer has very limited treatment options to date, with cisplatin and paclitaxel being the most common and efficient. Recently, a significant increase in heat shock factor 1 (HSF1) expression has been found in highly malignant ovarian cancer. HSF1 is the regulator of the heat shock response (HSR) and promotes the transcription of heat shock proteins (HSPs). Previous studies have shown that HSF1-induced chaperone activity may act to stabilize multiple oncogenes within many different cancer types. This leads to cancer proliferation, reduced apoptosis, and metastasis. In this study, we examine gene expression changes through microarray analysis in spheroid versus monolayer ovarian cancer cells treated with TGFβ to induce EMT. Interestingly, EMT and stress response pathways, including the heat shock response, were all significantly affected by 3D growth. HSF1 knockdown was utilized in both 2D and 3D cultures to further study this response. HSF1 knockdown is shown to inhibit ovarian cancer progression in both monolayer and spheroid model cells. Moreover, HSF1 knockdown in spheroid cells has a significantly greater impact on EMT markers than it does in 2D cultures. This indicates HSF1 may be a utilized as a target for chemotherapeutics in ovarian cancer patients and could potentially have implications in other such hormonal cancers.

Citation Format: Trillitye Paullin, Chase Powell, Menzie Christopher, Robert Hill, Christopher Martyniuk, Sandy Westerheide. The heat shock transcription factor HSF1 induces ovarian cancer epithelial-mesenchymal transition in a 3-D spheroid growth model. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A41.