Germline Testing identifies Pathogenic/Likely Pathogenic Variants in Patients with Pancreatic Neuroendocrine Tumors

10% of pancreatic neuroendocrine tumors (pNETs) are related to inherited syndromes (MEN1, MEN4, VHL, NF1, TSC). Growing evidence suggests that clinically sporadic pNETs can also harbor germline pathogenic variants. In this study, we report the prevalence of pathological/likely pathological germline variants (P/LP) in a high-risk cohort and an unselected cohort. We collected clinical data of patients with pNETs seen at MD Anderson Cancer Center (MDACC) and Johns Hopkins Hospital (JHH). High-risk cohort included (n=132) patients seen at MDACC who underwent germline testing for high-risk criteria (early onset, personal or family history of cancer and syndromic features) between 2013-2019. Unselected cohort (n=106) patients seen at JHH who underwent germline testing following their diagnosis of pNETs between 2020 to 2022. In the high-risk cohort (n=132), 33% (n=44) had P/LP variants. The majority of the patients had P/LP variants in MEN1 56% (n=25), followed by DNA repair pathways 18% (n=8), and 7 %(n=3) in MSH2 (Lynch Syndrome). Patients with P/LP were younger (45 years vs 50 years; p=0.002). In the unselected cohort (n=106), 21% (n=22) had P/LP. The majority were noted in DNA repair pathways 40% (n=9) and MEN1 36% (n=8). Multifocal tumors correlated with the presence of P/LP (p=0.0035). MEN1 germline P/LP variants correlated with younger age (40 vs 56 years) (p=0.0012). presence of multifocal tumors (p<0.0001), and WHO grade 1 histology (p=0.0078). P/LP variants are prevalent in patients with clinically sporadic pNET irrespective of high-risk features. The findings support upfront universal germline testing in all pNET patients.

Gut epithelial Interleukin-17 receptor A signaling can modulate distant tumors growth through microbial regulation

Microbes influence cancer initiation, progression and therapy responsiveness. IL-17 signaling contributes to gut barrier immunity by regulating microbes but also drives tumor growth. A knowledge gap remains regarding the influence of enteric IL-17-IL-17RA signaling and their microbial regulation on the behavior of distant tumors. We demonstrate that gut dysbiosis induced by systemic or gut epithelial deletion of IL-17RA induces growth of pancreatic and brain tumors due to excessive development of Th17, primary source of IL-17 in human and mouse pancreatic ductal adenocarcinoma, as well as B cells that circulate to distant tumors. Microbial dependent IL-17 signaling increases DUOX2 signaling in tumor cells. Inefficacy of pharmacological inhibition of IL-17RA is overcome with targeted microbial ablation that blocks the compensatory loop. These findings demonstrate the complexities of IL-17-IL-17RA signaling in different compartments and the relevance for accounting for its homeostatic host defense function during cancer therapy.

Bacterial and fungal characterization of pancreatic adenocarcinoma from Endoscopic Ultrasound-guided biopsies

Introduction

The tumor microbiome (TM) has been linked to pancreatic cancer prognosis. Specific microbes can confer tumor resistance to therapies. Early knowledge of the TM at time of diagnosis would be clinically relevant for precision therapy based on microbial composition. However, it is difficult to define the TM prior to surgical resection.

Methods

In this pilot feasibility study, patients underwent Endoscopic Ultrasound-Fine Needle Aspiration (EUS-FNA) biopsy of pancreatic adenocarcinoma. These samples were analyzed using 16S rRNA and internal transcribed spacer (ITS) sequencing for characterization of the tumor bacteria and fungi.

Result

After in silico decontamination and comparison to non-matched tumor, we were able to characterize the TM in biopsies, which was comparable to the TM from surgical specimens.

Discussion

EUS-FNA biopsy may represent a feasible modality to characterize the pancreatic TM prior to surgical resection with proper decontamination strategies and improvements in matched controls.

Abstract 5918: Interrogating host-intratumoral microbial interactions in pancreatic cancer

Cancer is increasingly becoming a rising cause of mortality worldwide. Microbiota, both within the gut and tumors, has emerged as a significant player influencing tumor growth and responses to therapies. The tumor niche provides a privileged microenvironment for microbial colonization. Recent evidence links microbiota and pancreatic tumorigenesis. Pancreatic ductal adenocarcinoma (PDAC), is an aggressive cancer surrounded by a highly immuno-suppressive tumor microenvironment (TME) which limits efficacy of most available therapies. We have previously reported that rare long-term survival in pancreatic cancer is associated with an intratumoral microbial signature which correlates with enhanced TME immunoactivation, suggestive of microbial mediated immune cell recruitment. A gut-to-tumor microbial crosstalk was also found in a human-to-mouse Fecal Microbiota Transplant (FMT) tumor model. While we have identified the vital role of microbiota in affecting tumor immunity, there is still a gap of knowledge about local microbial interactions within TME. Deeper understanding of the microbial mediated events that are triggered and follow PDAC development, which act to induce and support tumor growth, would provide us with potential novel targets that could be blocked to reverse PDAC immunosuppression and tumor growth. To interrogate the features of the pancreatic tumor microbial niche, we performed spatial co-detection of microbial and host targets to identify the cellular compartment which interacts with microbes inside the TME in clinical samples. We developed novel qualitative and quantitative imaging methodologies for evaluating crosstalk between the host and microbes. We also evaluated the effect of microbial burden on transcriptomic changes in host cells through multiple spatial sequencing approaches. Overall, we dissect the functional role of microbes in orchestrating TME organization and their effect on tumor signaling.

Citation Format: Vidhi Chandra, Hajar Rajaei, Seyda Baydogan, Javier Gomez, Sammy Ferri-Borgogno, Anirban Maitra, Erick Riquelme, Ismet Sahin, Jared Burks, Michael Kim, Florencia McAllister. Interrogating host-intratumoral microbial interactions in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5918.

Prospective characterization of oral and gut microbiome in a high-risk pancreatic cancer cohort

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Background: Pancreatic cancer (PC) is the third leading cause of cancer death in the United States. The high mortality associated with PC is attributed to multiple reasons: lack of effective therapies, aggressive biology and late diagnosis. Due to the absence of reliable early disease biomarkers, PC screening is largely dependent on imaging. Recent studies have highlighted the importance of the gut and tumor microbiome in PC. We present here the first report of oral and gut microbiome prospective analysis of PC high-risk individuals (PC-HRI) undergoing screening. Methods: We collected periodontal and stool samples at the University of Texas MD Anderson Cancer Center from 2017-2022. A total of 448 samples, consisting of 250 oral and 198 gut samples were obtained. Samples were collected from PC (n=73), PC-HRI (n=34), and healthy (n=143) individuals. 16s rRNA sequencing was used to characterize the oral and gut microbiome and statistical analysis and correlation with imaging and clinical characteristics were performed. Results: We identified three phyla, namely Proteobacteria, Actinobacteria, and Fusobacteria as significantly more abundant in the gut microbiome of PC patients. Conversely, Proteobacteria was decreased in the oral microbiome of PC patients. At the class level, Gammaproteobacteria (GP) oral/gut ratio was significantly decreased in PC patients compared with healthy individuals (p=0.02). Analysis of PC-HRI revealed also low GP oral/gut ratio in high-risk individuals who were diagnosed with worrisome pancreatic focal lesions. Interestingly, Gammaproteobacteria (GP) is one of the main classes of bacteria detected in pancreatic cancer tissue. GP shifts in oral and gut environments could be implicated in pancreatic early tumorigenesis and serve as biomarker of the disease. Additionally, gut bacteria with metabolic pathways related to lipid metabolism were more enriched in PC patients and PC-HRI with focal lesions compared to healthy controls. Conclusions: Gammaproteobacteria oral/gut ratio represents a potential novel biomarker which could predict presence of early high risk-pancreatic focal lesions in PC-HRI. Taken together, this report provides observational evidence about changes in oral and gut microbiome in patients with pancreatic cancer but even more importantly, the fact that those changes could be detected in PC-HRI with early high-risk lesions. Broader validation in other high-risk cohorts would be required. Detection of GP oral/gut ratio would represent an inexpensive, non-invasive method that could be useful for PC screening. Functional studies should be performed to determine how GP shifts can contribute with pancreatic tumorigenesis. Research supported by CPRIT (Grant Number: RP200173) and philanthropic funding through the MD Anderson Moonshot Program.

Exercise-induced engagement of the IL-15/IL-15Rα axis promotes anti-tumor immunity in pancreatic cancer

Aerobic exercise is associated with decreased cancer incidence and cancer-associated mortality. However, little is known about the effects of exercise on pancreatic ductal adenocarcinoma (PDA), a disease for which current therapeutic options are limited. Herein, we show that aerobic exercise reduces PDA tumor growth, by modulating systemic and intra-tumoral immunity. Mechanistically, exercise promotes immune mobilization and accumulation of tumor-infiltrating IL15Rα+ CD8 T cells, which are responsible for the tumor-protective effects. In clinical samples, an exercise-dependent increase of intra-tumoral CD8 T cells is also observed. Underscoring the translational potential of the interleukin (IL)-15/IL-15Rα axis, IL-15 super-agonist (NIZ985) treatment attenuates tumor growth, prolongs survival, and enhances sensitivity to chemotherapy. Finally, exercise or NIZ985 both sensitize pancreatic tumors to αPD-1, with improved anti-tumor and survival benefits. Collectively, our findings highlight the therapeutic potential of an exercise-oncology axis and identify IL-15 activation as a promising treatment strategy for this deadly disease.

Abstract 2244: Video-based germline testing for individuals with pancreatic ductal adenocarcinoma: Influence of COVID-19 pandemic

Purpose: National guidelines recommend universal germline genetic testing (GT) for patients with Pancreatic Ductal Adenocarcinoma (PDAC), but rates of testing remain low. Given the aggressiveness of PDAC, the window of opportunity for GT is short and often overshadowed by treatment initiation and other clinical milestones. Thus, there is an unmet need for a model that streamlines GT and makes it available to a wider audience in a rapid fashion. Moreover, in pandemic times, video-based alternatives for medical care are increasingly relevant.

Methods: We implemented a novel care delivery model in which a seven-minute educational video describing the benefits, risks, and implications of GT was shown to PDAC patients. The video was shown in lieu of an initial consult with a genetic counselor. Only patients who had not undergone GT or previously met with a genetic counselor were included. After watching the video, patients could elect to pursue GT and get tested on-side or remotely (at home). Genetic counselors disclosed results and provided post-test counseling by phone. Clinical and germline data were collected through medical records on a cohort of PDAC patients seen at the Gastrointestinal Center-MD Anderson during a 2-year enrollment period (May 2019-July 2021), which included the COVID-19 pandemic period.

Results: A total of 286 PDAC patients watched the educational video. From 175 patients that watched the video pre-pandemic, 12 declined testing, whereas in the post-pandemic period, none of the 111 patients declined testing (6.9% vs 0%; p&lt;0.004). We excluded data from 29 patients who elected to undergo GT but declined to participate in the registry. From the 241 patients with successfully collected samples, 21 patients (8.7%) had a pathogenic variant (PV), 38 patients (15.8%) had a Variant of Uncertain Significance (VUS), and 182 patients (75.5%) tested negative. The pathogenic variants detected included: BRCA2 (most frequent), ATM, BRCA1, CDKN2A, PALB2 and APC.

Conclusions: GT can have tremendously beneficial effects, such as qualifying for targeted treatment options and facilitating cancer prevention in probands’ at-risk family members. Comparing uptake of GT pre- versus post-pandemic suggests that patients were more willing to trust information from a video platform, likely due to the global effect of living in a “virtual“ society as a result of the pandemic. We suggest an approach in which every PDAC patient is shown a genetics educational video and given the choice to undergo GT and post-result counseling, greatly reducing the burden on genetic counselors. We report here the feasibility of implementing video-based germline testing in PDAC patients which resulted in unexpectedly high uptake levels, particularly post-pandemic. Further investigations are needed to explore the feasibility of a fully remote GT model in diverse populations to assess additional barriers to universal GT.

Citation Format: Saumya Kasliwal, Seyda Baydogan, Devon Harrison, Mark Hurd, Maureen Mork, Anirban Maitra, Florencia McAllister. Video-based germline testing for individuals with pancreatic ductal adenocarcinoma: Influence of COVID-19 pandemic [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 2244.

Antibiotic use influences outcomes in advanced pancreatic adenocarcinoma patients

Recent studies defined a potentially important role of the microbiome in modulating pancreatic ductal adenocarcinoma (PDAC) and responses to therapies. We hypothesized that antibiotic usage may predict outcomes in patients with PDAC.

We retrospectively analyzed clinical data of patients with resectable or metastatic PDAC seen at MD Anderson Cancer from 2003 to 2017. Demographic, chemotherapy regimen and antibiotic use, duration, type, and reason for indication were recorded.

A total of 580 patients with PDAC were studied, 342 resected and 238 metastatic patients, selected retrospectively from our database. Antibiotic use, for longer than 48 hrs, was detected in 209 resected patients (61%) and 195 metastatic ones (62%). On resectable patients, we did not find differences in overall survival (OS) or progression‐free survival (PFS), based on antibiotic intake. However, in the metastatic cohort, antibiotic consumption was associated with a significantly longer OS (13.3 months vs. 9.0 months, HR 0.48, 95% CI 0.34–0.7, p = 0.0001) and PFS (4.4 months vs. 2 months, HR 0.48, 95% CI 0.34–0.68, p = <0.0001). In multivariate analysis, the impact of ATB remained significant for PFS (HR 0.59, p = 0.005) and borderline statistically significant for OS (HR 0.69, p = 0.06). When we analyzed by chemotherapy regimen, we found that patients who received gemcitabine‐based chemotherapy as first‐line therapy (n = 118) had significantly prolonged OS (HR 0.4, p 0.0013) and PFS (HR 0.55, p 0.02) if they received antibiotics, while those receiving 5FU‐based chemotherapy (n = 98) had only prolonged PFS (HR 0.54, p = 0.03).

Antibiotics‐associated modulation of the microbiome is associated with better outcomes in patients with metastatic PDAC.

We have analyzed the effect of antibiotics’ intake on two cohorts of patients with pancreatic adenocarcinoma, resectable, and metastatic. We have found that on the metastatic cohort, antibiotics use was significantly associated with better outcomes, particularly, on patients that received gemcitabine based‐chemotherapy as the first line.

Interleukin-17-induced neutrophil extracellular traps mediate resistance to checkpoint blockade in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) remains a lethal malignancy with an immunosuppressive microenvironment that is resistant to most therapies. IL17 is involved in pancreatic tumorigenesis, but its role in invasive PDAC is undetermined. We hypothesized that IL17 triggers and sustains PDAC immunosuppression. We inhibited IL17/IL17RA signaling using pharmacological and genetic strategies alongside mass cytometry and multiplex immunofluorescence techniques. We uncovered that IL17 recruits neutrophils, triggers neutrophil extracellular traps (NETs), and excludes cytotoxic CD8 T cells from tumors. Additionally, IL17 blockade increases immune checkpoint blockade (PD-1, CTLA4) sensitivity. Inhibition of neutrophils or Padi4-dependent NETosis phenocopies IL17 neutralization. NMR spectroscopy revealed changes in tumor lactate as a potential early biomarker for IL17/PD-1 combination efficacy. Higher expression of IL17 and PADI4 in human PDAC corresponds with poorer prognosis, and the serum of patients with PDAC has higher potential for NETosis. Clinical studies with IL17 and checkpoint blockade represent a novel combinatorial therapy with potential efficacy for this lethal disease.

Abstract PO-014: Interleukin 17 induced- neutrophil extracellular traps (NETs) mediate resistance to checkpoint blockade in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) continues to be an aggressive disease with an immunosuppressive tumor microenvironment, which is recalcitrant to most therapies. Interleukin-17 (IL-17), a potent pro-inflammatory cytokine, has been implicated in initiation of pancreatic premalignant lesions but its role in invasive PDAC has not been widely explored. We hypothesized that IL-17 triggers and sustains immunosuppression during PDAC. We employed pharmacological and genetic strategies to inhibit IL-17/IL-17RA signaling axis and characterized the tumor microenvironment with RNA sequencing, mass & flow cytometry and quantitative multiplex immunofluorescence. Our analysis revealed that IL-17 signaled through tumor cells to recruit neutrophils into the tumor microenvironment and spatially exclude cytotoxic CD8 T cells. Furthermore, IL-17 signaling in tumor cells triggered neutrophils to form extracellular traps (NETs), a primary mechanism mediating PDAC immunosuppression. Genetic or pharmacological inhibition of IL-17 overcame resistance to immune checkpoint blockade (PD-1, CTLA-4), in a CD8 T cell dependent manner. Inhibition of neutrophils or Padi4-dependent NETosis phenocopied IL-17 neutralization. Higher expression of IL-17 and PADI4 in human PDAC corresponded with poorer prognosis, according to TCGA data. Serum from PDAC patients had a higher capacity for NET formation and diminished ability for NET degradation in control neutrophils, in comparison to serum from healthy donors. In conclusion, the cross-talk of IL-17 with pancreatic cancer cells orchestrates neutrophil recruitment and activation of Padi4 dependent NETosis, ultimately resulting in spatial remodeling of the stroma and immunosuppression. IL-17 inhibition overcomes resistance to checkpoint blockade in a CD8 T cell dependent fashion. Clinical studies with IL-17 inhibitors and checkpoint blockade represent a promising novel combinatorial therapy for this lethal disease.

Citation Format: Vidhi Chandra, Yu Zhang, Erick Riquelme, Prasanta Dutta, Pompeyo R. Quesada, Amanda Rakoski, Michelle Zoltan, Nivedita Arora, Seyda Baydogan, William Horne, Jared Burks, Hanwen Xu, Perwez Hussain, Huamin Wang, Sonal Gupta, Anirban Maitra, Jennifer M. Bailey, Seyed J. Moghaddam, Sulagna Banerjee, Ismet Sahin, Pratip Bhattacharya, Florencia McAllister. Interleukin 17 induced- neutrophil extracellular traps (NETs) mediate resistance to checkpoint blockade in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-014.

Abstract 4262: MiR-873 is the master regulator of autophagy genes through a novel negative feedback mechanism mediated by Elongation factor 2 kinase (eEF-2K) and suppresses tumor growth and progression of triple negative breast cancer

Autophagy is a highly complex lysosomal degradation process. Recently we demonstrated that autophagy genes encoding Beclin1, ATG7, LC3 promotes cell proliferation, survival, and invasion by promoting Cyclin D1 and Integrin β1/ Src signaling in triple negative breast cancer (TNBC). Studies showed that increased basal autophagy is linked to development of chemoresistance, relapses and metastasis and poor prognosis in TNBC. However, the major molecular mechanisms and the integrated global regulators controlling the autophagic machinery still remains unknown. Here, we identified miRNA-873 as a p53-driven tumor suppressor that is associated with favorable patient survival (TCGA database) and the key factor for regulating the major autophagy genes, including BCN1, LC3, ATG7, ATG16L1 and ATG13 in TNBC. Using in silico prediction algorithms we demonstrated that miR-873 has binding sites on the 3’-untranslated region (3’-UTR) of these genes and directly binds and suppresses their expression using by gene reporter assays. Introduction of mutations to the miR-873 binding sites on 3-UTR of these genes reversed the inhibitory effect of miR-873on these genes. Furthermore, knockdown of Beclin1, LC3 and ATG7 genes significantly suppressed Eukaryotic Elongation Factor-2 kinase (eEF2K), an unusual alpha kinase, which is highly overexpressed in TNBC patients and associated with poor prognosis. We also found that miR-873 also binds to the 3’-UTR of eEF2K mRNA and regulates its expression and inhibits starvation induced autophagy. Through knockdown and overexpression studies we also demonstrated that eEF2K regulates expression of abovementioned autophagic proteins. Interestingly, we found that BCN1, LC3, and ATG7 also regulates expression of EF2K, suggesting an existence of a novel negative feed-back loop. Lastly, we demonstrated that miR-873 expression is suppressed in TNBC patients and cell lines and restoration of its expression in vivo in MDA-MB-231 and MDA-MB-436 orthotopic xenograft models by systemic injection (I.V, tail vein once a week, 0.15 mg/kg) of miR-873 mimic molecules incorporated in novel single lipid (SLNP)-nanoparticles suppressed tumor growth. Furthermore, in vivo treatment of mice with SLNP-Beclin1, ATG7 or ATG8 siRNAs also completely suppressed TNBC tumor growth. In conclusion, our data suggest that p53/miR-873/eEF2K axis is a novel post-transcriptional regulator of autophagy and miR-873 functions as a master regulator of the post-transcriptional regulation of the major autophagy genes directly and indirectly through eEF2K dependent dual-suppressor mechanism and modulation of this axis could be used as a potential therapy for TNBC.

Citation Format: Hamada Ahmed Mokhlis, Nermin Kahraman, Seyda Baydogan, Abdel-Aziz Hamed Abdel-Aziz, Ahmed Ashour, Cristina Ivan, Gabriel Lopez-Berestein, Bulent Ozpolat. MiR-873 is the master regulator of autophagy genes through a novel negative feedback mechanism mediated by Elongation factor 2 kinase (eEF-2K) and suppresses tumor growth and progression of triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4262.

Abstract 3563: Exosomal transfer of tumor-associated macrophage derived miR-6068 promote ovarian cancer progression

Ovarian cancer, especially high-grade serous ovarian cancer (HGSOC), is the deadliest gynecological cancer with 50-70% 5-year mortality rates. Every year more than 22,000 new cases of ovarian cancer and 15,000 deaths are anticipated within the United States only. Recent clinical and experimental evidence indicates that tumor-associated macrophages (TAMs), the most abundant cells in the tumor microenvironment, play a significant role in tumor growth and progression by contributing to angiogenesis, invasion, metastasis, and drug resistance, leading to poor clinical outcomes and significantly shorter patient survival in HGSOC. More than 50% of cells in the peritoneal tumor microenvironment and malign ascites consist of TAMs in ovarian cancer (OC) patients. Especially, M2 macrophages have been shown to support tumor proliferation and promote tumor progression, angiogenesis, and drug resistance. But the mechanisms of these oncogenic effects are still not clear. The goal of our study to investigate the role of TAM-derived exosomes, which are 30-100nm microvesicles released from cells and are key factors in communication between cancer cells and the tumor microenvironment. To this end, we evaluated differentially expressed miRNAs in high-grade ovarian cancer cells (OVCAR3, OVCAR 432 and OVCAR5) after treatment with exosomes-derived from TAMs (M2 phenotype) using the Affymetrix Gene Chip miRNA 4.0 microarrays. We identified several miRNAs, including miR-6068 that we validated by qPCR and found it to be significantly upregulated in both HGSOC cells and their exosomes. We demonstrated that transfection of HGSOC cells with miR-6068 significantly increased proliferation, migration and invasion capacities of the cells in vitro, suggesting that this miR-6068 act as an oncogenic miR (oncomiR). Using in silico prediction algorithms we found that miR-6068 has binding sites on the 3’-untranslated region (3’-UTR) of PTPN4 gene encoding a phosphatase and demonstrated that it miR-6068 suppresses PTPN4 expression by Western blot and qPCR. Inhibition of PTPN4 by siRNA significantly induced cell proliferation in OC cells, suggesting that PTPN4 acts as a tumor suppressor. In conclusion, our results suggest that miR-6068 has an oncogenic role in ovarian cancer progression by targeting PTPN4 and may be a novel effective therapeutic target for ovarian cancer.

Citation Format: Seyda Baydogan, Jianting Sheng, Nermin Kahraman, Pinar Kanlikilicer, Hamada Ahmed Mokhlis, Sayra Dilmac, Stephen T. C. Wong, Bulent Ozpolat. Exosomal transfer of tumor-associated macrophage derived miR-6068 promote ovarian cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3563.

Exosomal miRNA confers chemo resistance via targeting Cav1/p-gp/M2-type macrophage axis in ovarian cancer

Background

Circulating miRNAs are known to play important roles in intercellular communication. However, the effects of exosomal miRNAs on cells are not fully understood.

Methods

To investigate the role of exosomal miR-1246 in ovarian cancer (OC) microenvironment, we performed RPPA as well as many other in vitro functional assays in ovarian cancer cells (sensitive; HeyA8, Skov3ip1, A2780 and chemoresistant; HeyA8-MDR, Skov3-TR, A2780-CP20). Therapeutic effect of miR-1246 inhibitor treatment was tested in OC animal model. We showed the effect of OC exosomal miR-1246 uptake on macrophages by co-culture experiments.

Findings

Substantial expression of oncogenic miR-1246 OC exosomes was found. We showed that Cav1 gene, which is the direct target of miR-1246, is involved in the process of exosomal transfer. A significantly worse overall prognosis were found for OC patients with high miR-1246 and low Cav1 expression based on TCGA data. miR-1246 expression were significantly higher in paclitaxel-resistant OC exosomes than in their sensitive counterparts. Overexpression of Cav1 and anti-miR-1246 treatment significantly sensitized OC cells to paclitaxel. We showed that Cav1 and multi drug resistance (MDR) gene is involved in the process of exosomal transfer. Our proteomic approach also revealed that miR-1246 inhibits Cav1 and acts through PDGFβ receptor at the recipient cells to inhibit cell proliferation. miR-1246 inhibitor treatment in combination with chemotherapy led to reduced tumor burden in vivo. Finally, we demonstrated that when OC cells are co-cultured with macrophages, they are capable of transferring their oncogenic miR-1246 to M2-type macrophages, but not M0-type macrophages.

Interpretation

Our results suggest that cancer exosomes may contribute to oncogenesis by manipulating neighboring infiltrating immune cells. This study provide a new mechanistic therapeutic approach to overcome chemoresistance and tumor progression through exosomal miR-1246 in OC patients.

Comparison of two different antibiotic regimens for the prophylaxisis of cases with preterm premature rupture of membranes: a randomized clinical trial

OBJECTIVES

The aim of the study was to assess the effect of 1 g ampicillin prophylactic dosage whether it is as effective as the dosage of 2 g to prevent maternal and neonatal morbidity in a randomized manner.

MATERIALS AND METHODS

One hundred and fourty eight singleton pregnant women with preterm premature rupture of membranes between 21 and 33 weeks of gestation were followed-up during the study period in our institution. We com-pared the efficacy of two different different dosages of ampicillin. The study population was randomized into 2 groups. In the group 1, 1 g of intravenous ampicillin was given every 6 hours. In the group 2, 2 g of intravenous ampicillin was given every 6 hours.

RESULTS

There was no significant difference between groups interms of fetal complications (RDS, icterus, mortality, sepsis, transient tachypnea of newborn and the pneumonia), rate of intensive care unit admission, fetal gender, fever, rate of clinical chorioamnionitis, high white blood cell count and the CRP, rate of cases < 30 weeks (p > 0.05). There was a significant differ-ence between the groups for the rate of previous preterm premature rupture of membranes history, steroid administration and the need for tocolysis (p < 0.05).

CONCLUSIONS

Although antibiotics seems to be innocent, several side effects have been introduced. It is reasonable to use the lowest dosages in shortest period in order to minimize these unwanted effects.