GPX3 supports ovarian cancer tumor progression in vivo and promotes expression of GDF15

OBJECTIVE

We previously reported that high expression of the extracellular glutathione peroxidase GPX3 is associated with poor patient outcome in ovarian serous adenocarcinomas, and that GPX3 protects ovarian cancer cells from oxidative stress in culture. Here we tested if GPX3 is necessary for tumor establishment in vivo and to identify novel downstream mediators of GPX3's pro-tumorigenic function.

METHODS

GPX3 was knocked-down in ID8 ovarian cancer cells by shRNA to test the role of GPX3 in tumor establishment using a syngeneic IP xenograft model. RNA sequencing analysis was carried out in OVCAR3 cells following shRNA-mediated GPX3 knock-down to identify GPX3-dependent gene expression signatures.

RESULTS

GPX3 knock-down abrogated clonogenicity and intraperitoneal tumor development in vivo, and the effects were dependent on the level of GPX3 knock-down. RNA sequencing showed that loss of GPX3 leads to decreased gene expression patterns related to pro-tumorigenic signaling pathways. Validation studies identified GDF15 as strongly dependent on GPX3. GDF15, a member of the TGF-β growth factor family, has known oncogenic and immune modulatory activities. Similarly, GPX3 expression positively correlated with pro-tumor immune cell signatures, including regulatory T-cell and macrophage infiltration, and displayed significant correlation with PD-L1 expression.

CONCLUSIONS

We show for the first time that tumor produced GPX3 is necessary for ovarian cancer growth in vivo and that it regulates expression of GDF15. The immune profile associated with GPX3 expression in serous ovarian tumors suggests that GPX3 may be an alternate marker of ovarian tumors susceptible to immune check-point inhibitors.

GPX3 supports ovarian cancer tumor progression in vivo and promotes expression of GDF15

Objective

We previously reported that high expression of the extracellular glutathione peroxidase GPX3 is associated with poor patient outcome in ovarian serous adenocarcinomas, and that GPX3 protects ovarian cancer cells from oxidative stress in culture. Here we tested if GPX3 is necessary for tumor establishment in vivo and to identify novel downstream mediators of GPX3's pro-tumorigenic function.

Methods

GPX3 was knocked-down in ID8 ovarian cancer cells by shRNA to test the role of GPX3 in tumor establishment using a syngeneic IP xenograft model. RNA sequencing analysis was carried out in OVCAR3 cells following shRNA-mediated GPX3 knock-down to identify GPX3-dependent gene expression signatures.

Results

GPX3 knock-down abrogated clonogenicity and intraperitoneal tumor development in vivo, and the effects were dependent on the level of GPX3 knock-down. RNA sequencing showed that loss of GPX3 leads to decreased gene expression patterns related to pro-tumorigenic signaling pathways. Validation studies identified GDF15 as strongly dependent on GPX3. GDF15, a member of the TGF-β growth factor family, has known oncogenic and immune modulatory activities. Similarly, GPX3 expression positively correlated with pro-tumor immune cell signatures, including regulatory T-cell and macrophage infiltration, and displayed significant correlation with PD-L1 expression.

Conclusions

We show for the first time that tumor produced GPX3 is necessary for ovarian cancer growth in vivo and that it regulates expression of GDF15. The immune profile associated with GPX3 expression in serous ovarian tumors suggests that GPX3 may be an alternate marker of ovarian tumors susceptible to immune check-point inhibitors.

Alternative splice variants of the mitochondrial fission protein DNM1L/Drp1 regulate mitochondrial dynamics and tumor progression in ovarian cancer

Aberrant mitochondrial fission/fusion dynamics have been reported in cancer cells. While post translational modifications are known regulators of the mitochondrial fission/fusion machinery, we show that alternative splice variants of the fission protein Drp1 (DNM1L) have specific and unique roles in cancer, adding to the complexity of mitochondrial fission/fusion regulation in tumor cells. Ovarian cancer specimens express an alternative splice transcript variant of Drp1 lacking exon 16 of the variable domain, and high expression of this splice variant relative to other transcripts is associated with poor patient outcome. Unlike the full-length variant, expression of Drp1 lacking exon 16 leads to decreased association of Drp1 to mitochondrial fission sites, more fused mitochondrial networks, enhanced respiration, and TCA cycle metabolites, and is associated with a more metastatic phenotype in vitro and in vivo. These pro-tumorigenic effects can also be inhibited by specific siRNA-mediated inhibition of the endogenously expressed transcript lacking exon 16. Moreover, lack of exon 16 abrogates mitochondrial fission in response to pro-apoptotic stimuli and leads to decreased sensitivity to chemotherapeutics. These data emphasize the significance of the pathophysiological consequences of Drp1 alternative splicing and divergent functions of Drp1 splice variants, and strongly warrant consideration of Drp1 splicing in future studies.

Abstract A034: Orchestrated expression of the atypical Rho-GTPase, RHOV, in response to matrix detachment of ovarian cancer cells

Ovarian cancer (OVCA) metastasis occurs through the process of transcoelomic spread, where cells disseminate into the peritoneal fluid and form multi-cellular aggregates (MCA) that mediate Anchorage-Independent (A-I) survival and invasion of the peritoneal organs. Isolation of MCAs from patient ascites has been extensively reported in the literature and found to correlate with poor patient survival and resistance to therapy. However, the mechanisms promoting OVCA MCA formation and survival in A-I are not fully understood. We previously demonstrated that MCAs upregulate their mitochondrial antioxidant defenses to maintain optimal survival in A-I, and that this is an early event following cellular detachment. To identify additional key molecular players promoting MCA formation and fitness in A-I, we employed sequential RNA seq analysis to compare the transcriptome of cells in attached, early A-I, and late A-I conditions using the serous cell line OVCA433. Analysis of early transcriptomic changes observed within 2hrs of A-I revealed that RHOV, a recently identified atypical member of the Rho GTPase family, is the top gene significantly upregulated in early A-I. Moreover, we found that RHOV expression rapidly declines in later A-I timepoints indicative of a tight temporal regulation of RHOV expression following cellular detachment. Next, we compared the expression of RHOV in primary ovarian tumor cells and matching malignant ascites cells from the publicly available dataset (GEO: GSE85296) and found increased RHOV expression specifically in the metastatic ascites of ovarian cancer patients when compared to the attached tumor. Previously, RHOV expression was found to regulate intercellular adhesion dynamics during specific stages of neural crest development, a physiological process mimicking epithelial to mesenchymal transition (EMT). RHOV has also been reported to be overexpressed in lung cancer where it was found to correlate with poor patient outcome and resistance to therapy. However, the role of RHOV in ovarian cancer metastasis remains unexplored. To test the consequences of increased RHOV transcription in A-I: its role in migration, aggregate formation, and anoikis resistance is being tested following silencing of RHOV expression using both CRISPR and siRNA. Current work is exploring how RHOV is rapidly transcribed following matrix detachment and how increased expression alters cellular signaling events in early A-I stages to promote optimal MCA fitness. This work aims to contribute new knowledge on the novel oncogenic role of an understudied member of the Rho family of GTPases, RHOV. Moreover, given that increased MCA fitness has been correlated with increases metastatic potential and resistance to therapy, we provide a unique proof-of-concept study to target key components of early MCA adaptations as a novel therapeutic strategy for prolonging survival rates in OVCA patients diagnosed in metastatic stages.

Citation Format: Amal T. Elhaw, Yeon Soo Kim, Zaineb Javed, Priscilla Tang, Weihua Pan, Nadine Hempel. Orchestrated expression of the atypical Rho-GTPase, RHOV, in response to matrix detachment of ovarian cancer cells [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr A034.

Emerging perspectives on growth factor metabolic relationships in the ovarian cancer ascites environment

The ascites ecosystem in ovarian cancer is inhabited by complex cell types and is bathed in an environment rich in cytokines, chemokines, and growth factors that directly and indirectly impact metabolism of cancer cells and tumor associated cells. This milieu of malignant ascites, provides a 'rich' environment for the disease to thrive, contributing to every aspect of advanced ovarian cancer, a devastating gynecological cancer with a significant gap in targeted therapeutics. In this perspective we focus our discussions on the 'acellular' constituents of this liquid malignant tumor microenvironment, and how they influence metabolic pathways. Growth factors, chemokines and cytokines are known modulators of metabolism and have been shown to impact nutrient uptake and metabolic flexibility of tumors, yet few studies have explored how their enrichment in malignant ascites of ovarian cancer patients contributes to the metabolic requirements of ascites-resident cells. We focus here on TGF-βs, VEGF and ILs, which are frequently elevated in ovarian cancer ascites and have all been described to have direct or indirect effects on metabolism, often through gene regulation of metabolic enzymes. We summarize what is known, describe gaps in knowledge, and provide examples from other tumor types to infer potential unexplored roles and mechanisms for ovarian cancer. The distribution and variation in acellular ascites components between patients poses both a challenge and opportunity to further understand how the ascites may contribute to disease heterogeneity. The review also highlights opportunities for studies on ascites-derived factors in regulating the ascites metabolic environment that could act as a unique signature in aiding clinical decisions in the future.

Abstract 128: SIRT3 supports anchorage-independent survival of ovarian cancer cells

Metabolic changes during tumor progression have numerous consequences on cancer cells, including an increased risk of cell death due to production of reactive oxygen species (ROS). Antioxidant defense adaptations thus accompany metabolic alterations as essential survival mechanisms during metastasis. We observe that oxidative phosphorylation is increased when ovarian cancer (OC) cells transition to anchorage independence (a-i), an important step during metastasis in the peritoneal cavity. To combat the rise in oxidative stress resulting from this metabolic shift, a rapid increase in the sirtuin 3 (SIRT3)/superoxide dismutase 2 (SOD2) axis occurs to reduce the mitochondrial superoxide anion surge and to maintain cellular viability. We demonstrate that this upregulation occurs in transcription, translation, and SIRT3-mediated regulation of SOD2 activity. However, the fate of the hydrogen peroxide (H2O2) resulting from superoxide dismutation through SIRT3/SOD2 remains unknown. RNAseq analysis of attached versus a-i conditions revealed a significant downregulation of peroxiredoxin 3, a major scavenger of H2O2 in the mitochondria, suggesting that OCs have a net increase in mitochondrial H2O2 in a-i. At sub-lethal levels, H2O2 serves as a second messenger of redox signaling, primarily via protein cysteine oxidation, which has been implicated with metastasis. We thus hypothesize that increases in SIRT3/SOD2/H2O2 play a role as mediators of redox signaling during OC anchorage-independent survival, spheroid formation and metastasis. Using the HyPer7 redox probe and manipulation of SIRT3 and SOD2 expression, H2O2 generation and localization in a-i are being assessed using 3D fluorescence microscopy. Moreover, siRNA mediated knock-down of SIRT3 in a-i leads to the downregulation of genes involved in specific signaling pathways, including NF-kB signaling, the inflammatory response, and metabolism. Mass-spec studies are underway to identify specific SIRT3 target proteins upstream of these transcriptional changes, by assessing global cysteine oxidation and the cellular acetylome to determine the role of H2O2-dependent redox signaling and SIRT3-dependent protein de-acetylation, respectively. Given the increase in SIRT3-dependent inflammatory signaling in a-i, we are exploring how the SIRT3/SOD2/H2O2 axis influences OC interaction with tumor associated macrophages and mesenchymal stem cells, commonly found in the ascites tumor environment. This work demonstrates a multi-faceted role for the SIRT3/SOD2/H2O2 axis in a-i survival, a key step during OC metastasis.

Citation Format: Priscilla Tang, Yeon Soo Kim, Piyushi Gupta-Vallur, Amal T. Elhaw, Zaineb Javed, Weihua Pan, Nadine Hempel. SIRT3 supports anchorage-independent survival of ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 128.

Abstract 3781: Expression of ovarian cancer specific Drp1 splice variants regulate mitochondrial heterogeneity and cell plasticity during tumor progression

Mitochondrial shape is integral for its proper function and is maintained by a dynamic balance between the events of fission and fusion. Hence, a disruption in the balance is detrimental and has been associated with multiple pathologies including tumorigenesis. We noticed significant heterogeneity in mitochondrial morphology and function in ovarian cancer, which remains the deadliest gynecologic malignancy to date. We discovered that heterogenous mitochondrial dynamics in ovarian cancer cells were associated with specific transcript variant signatures of the fission protein Drp1 (encoded by the gene DNM1L), the primary GTPase responsible for mitochondrial fission. While several Drp1 splice variants have been reported, few studies have linked expression and potential interplay of splice variants of Drp1 on mitochondrial dynamics and function with pathophysiology especially in ovarian cancer. We used 3’RACE, western blotting and LC-MS/MS proteomics analysis to establish the identity of the major Drp1 splice variants expressed in ovarian cancer. We found ovarian cancer cell lines as well as patient-ascites derived cells, predominantly express two Drp1 variants: a transcript including both exons 16 and 17 (16/17) and a transcript lacking exon 16 (-/17). We also validated our findings in TCGA ovarian cancer specimens by analyzing Drp1 splice variant transcripts following annotation of TCGA raw RNAseq data and Salmon expression analysis. Our TCGA analysis of these variants highlighted significant difference in overall survival of ovarian cancer patients. Samples with high Drp1(-/17) expression were associated with poorer overall survival compared to those predominantly expressing Drp1(16/17). Furthermore, carrying out gene set enrichment analysis (GSEA) on TCGA specimens split by high expression of these two variants showed enrichment of distinct gene expression signatures. Overexpression and splice variant specific siRNA knockdown studies demonstrated that Drp1 variants have unique localization and effects on mitochondrial morphology and function. Furthermore, metabolic profiling and 13C metabolic flux analysis highlighted variant specific alterations in mitochondrial metabolic pathways and the TCA cycle. Drp1(-/17) expression enhanced mitochondrial respiratory function and as previously shown, Drp1(-/17) associated with both mitochondria and microtubules, potentially implying a more regulated fission activity as a consequence of controlled subcellular localization. Additionally, Drp1(-/17) was enriched and associated with quiescent phenotype compared to more proliferative phenotype of Drp1(16/17). Hence, expression of distinct Drp1 splice variants may be a novel mechanism to regulate mitochondrial fission, and integral to ovarian cancer cell plasticity under different selection pressures during tumor progression.

Citation Format: Zaineb Javed, Dong-Hui Shin, Weihua Pan, Amal Taher Elhaw, Priscilla Tang, Rebecca Phaeton, Mohamed Trebak, Vonn Walter, Nadine Hempel. Expression of ovarian cancer specific Drp1 splice variants regulate mitochondrial heterogeneity and cell plasticity during tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3781.

Optimization of Extracellular Flux Assay to Measure Respiration of Anchorage-independent Tumor Cell Spheroids

Three-dimensional (3D) cell culture models are widely used in tumor studies to more accurately reflect cell-cell interactions and tumor growth conditions in vivo. 3D anchorage-independent spheroids derived by culturing cells in ultra-low attachment (ULA) conditions is particularly relevant to ovarian cancer, as such cell clusters are often observed in malignant ascites of late-stage ovarian cancer patients. We and others have found that cells derived from anchorage-independent spheroids vary widely in gene expression profiles, proliferative state, and metabolism compared to cells maintained under attached culture conditions. This includes changes in mitochondrial function, which is most commonly assessed in cultured live cells by measuring oxygen consumption in extracellular flux assays. To measure mitochondrial function in anchorage-independent multicellular aggregates, we have adapted the Agilent Seahorse extracellular flux assay to optimize measurements of oxygen consumption and extracellular acidification of ovarian cancer cell spheroids generated by culture in ULA plates. This protocol includes: (i) Methods for culturing tumor cells as uniform anchorage-independent spheroids; (ii) Optimization for the transfer of spheroids to the Agilent Seahorse cell culture plates; (iii) Adaptations of the mitochondrial and glycolysis stress tests for spheroid extracellular flux analysis; and (iv) Suggestions for optimization of cell numbers, spheroid size, and normalization of oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) values. Using this method, we have found that ovarian cancer cells cultured as anchorage-independent spheroids display altered mitochondrial function compared to monolayer cultures attached to plastic dishes. This method allows for the assessment of mitochondrial function in a more relevant patho/physiological culture condition and can be adapted to evaluate mitochondrial function of various cell types that are able to aggregate into multicellular clusters in anchorage-independence. Graphic abstract: Workflow of the Extracellular Flux Assay to Measure Respiration of Anchorage-independent Tumor Cell Spheroids.

Monitoring of Insecticides resistance against cotton Jassid (Amrasca biguttutla biguttutla) under laboratory conditions

Development of insecticides resistance mainly hinge with managements techniques for the control of Jassid, Amrasca biguttutla biguttutla. Five insecticides were applied against field collected and laboratory rared jassid populations during the years of 2017 to 2019 to profile their resistance level against field population of jassid through leaf dip method. Very low resistance level was found in jassid against confidor whereas high level of resistance was observed by pyriproxyfen against other test insecticides. Gradual resistance was observed against diafenthiuron. It is concluded that for the management of Jassid repetition of same insecticide should be avoided. The use of confidor may be reduced to overcome resistance against Jassid.

Prospect of microbial food borne diseases in Pakistan: a review

Nowadays food borne illness is most common in people due to their epidemic nature. These diseases affect the human digestive system through bacteria, viruses and parasites. The agents of illness are transmitted in our body through various types of food items, water and uncooked. Pathogens show drastic changes in immunosuppressant people. This review gives general insights to harmful microbial life. Pakistan is a developed country and because of its improper food management, a lot of gastrointestinal problems are noted in many patients. Bacteria are most common agents to spread diarrhoea, villi infection, constipation and dysenteric disease in human and induce the rejection of organ transplant. Enhancement of their lifestyle, properly cooked food should be used and to overcome the outbreak of the diseases.

Effects of work-family conflict and job insecurity on psychological distress

Background

Work-family conflict (WFC) and job insecurity are important determinants of workers' mental health.

Aims

To examine the relationship between WFC and psychological distress, and the co-occurring effects of WFC and job insecurity on distress in US working adults.

Methods

This study used cross-sectional data from the 2010 National Health Interview Survey (NHIS) for adults aged 18-64 years. The 2010 NHIS included occupational data from the National Institute for Occupational Safety and Health (NIOSH) sponsored Occupational Health Supplement. Logistic regression models were used to examine the independent and co-occurring effects of WFC and job insecurity on distress.

Results

The study group consisted of 12059 participants. In the model fully adjusted for relevant occupational, behavioural, sociodemographic and health covariates, WFC and job insecurity were independently significantly associated with increased odds of psychological distress. Relative to participants reporting WFC only, participants reporting no WFC and no job insecurity had lower odds of moderate and severe distress. Co-occurring WFC and job insecurity was associated with significantly higher odds of both moderate [odds ratio (OR) = 1.55; 95% confidence interval (CI) 1.25-1.9] and severe (OR = 3.57; 95% CI 2.66-4.79) distress.

Conclusions

Rates of WFC and job insecurity were influenced by differing factors in working adults; however, both significantly increased risk of adverse mental health outcomes, particularly when experienced jointly. Future studies should explore the temporal association between co-occurring WFC and job insecurity and psychological distress.

Effects of human recombinant growth hormone on exercise capacity, cardiac structure, and cardiac function in patients with adult-onset growth hormone deficiency

Objective

Epidemiological studies suggest that adult-onset growth hormone deficiency (AGHD) might increase the risk of death from cardiovascular causes.

Methods

This was a 6-month double-blind, placebo-controlled, randomised, cross-over trial followed by a 6-month open-label phase. Seventeen patients with AGHD received either recombinant human growth hormone (rGH) (0.4 mg injection daily) or placebo for 12 weeks, underwent washout for 2 weeks, and were then crossed over to the alternative treatment for a further 12 weeks. Cardiac magnetic resonance imaging, echocardiography, and cardiopulmonary exercise testing were performed at baseline, 12 weeks, 26 weeks, and the end of the open phase (12 months). The results were compared with those of 16 age- and sex-matched control subjects.

Results

At baseline, patients with AGHD had a significantly higher systolic blood pressure, ejection fraction, and left ventricular mass than the control group, even when corrected for body surface area. Treatment with rGH normalised the insulin-like growth factor 1 concentration without an effect on exercise capacity, cardiac structure, or cardiac function.

Conclusion

Administration of rGH therapy for 6 to 9 months failed to normalise the functional and structural cardiac differences observed in patients with AGHD when compared with a control group.

Molecular markers for cell types of the inner ear and candidate genes for hearing disorders

To identify genes expressed in the vertebrate inner ear, we have established an assay that allows rapid analysis of the differential expression pattern of mRNAs derived from an auditory epithelium-specific cDNA library. We performed subtractive hybridization to create an enriched probe, which then was used to screen the cDNA library. After digoxigenin-labeled antisense cRNAs had been transcribed from hybridization-positive clones, we conducted in situ hybridization on slides bearing cryosections of late embryonic chicken heads, bodies, and cochleae. One hundred and twenty of the 196 clones analyzed encode 12 proteins whose mRNAs are specifically or highly expressed in the chicken's inner ear; the remainder encode proteins that occur more widely. We identified proteins that have been described previously as expressed in the inner ear, such as beta-tectorin, calbindin, and type II collagen. A second group of proteins abundant in the inner ear includes five additional types of collagens. A third group, including Coch-5B2 and an ear-specific connexin, comprises proteins whose human equivalents are candidates to account for hearing disorders. This group also includes proteins expressed in two unique cell types of the inner ear, homogene cells and cells of the tegmentum vasculosum.