Targeting MCL-1 triggers DNA damage and an anti-proliferative response independent from apoptosis induction

MCL-1 is a high-priority target due to its dominant role in the pathogenesis and chemoresistance of cancer, yet clinical trials of MCL-1 inhibitors are revealing toxic side effects. MCL-1 biology is complex, extending beyond apoptotic regulation and confounded by its multiple isoforms, its domains of unresolved structure and function, and challenges in distinguishing noncanonical activities from the apoptotic response. We find that, in the presence or absence of an intact mitochondrial apoptotic pathway, genetic deletion or pharmacologic targeting of MCL-1 induces DNA damage and retards cell proliferation. Indeed, the cancer cell susceptibility profile of MCL-1 inhibitors better matches that of anti-proliferative than pro-apoptotic drugs, expanding their potential therapeutic applications, including synergistic combinations, but heightening therapeutic window concerns. Proteomic profiling provides a resource for mechanistic dissection and reveals the minichromosome maintenance DNA helicase as an interacting nuclear protein complex that links MCL-1 to the regulation of DNA integrity and cell-cycle progression.

TOPBPing up DSBs with PARylation

Zhao et al. (2022) demonstrate that HIV Tat-specific factor 1, an RPA PARylation reader, recruits Topoisomerase IIβ-binding protein 1 to double-strand break sites specifically in the S phase of the cell cycle to promote homologous recombination.

Replication Stress: A Review of Novel Targets to Enhance Radiosensitivity-From Bench to Clinic

DNA replication is a process fundamental in all living organisms in which deregulation, known as replication stress, often leads to genomic instability, a hallmark of cancer. Most malignant tumors sustain persistent proliferation and tolerate replication stress via increasing reliance to the replication stress response. So whilst replication stress induces genomic instability and tumorigenesis, the replication stress response exhibits a unique cancer-specific vulnerability that can be targeted to induce catastrophic cell proliferation. Radiation therapy, most used in cancer treatment, induces a plethora of DNA lesions that affect DNA integrity and, in-turn, DNA replication. Owing to radiation dose limitations for specific organs and tumor tissue resistance, the therapeutic window is narrow. Thus, a means to eliminate or reduce tumor radioresistance is urgently needed. Current research trends have highlighted the potential of combining replication stress regulators with radiation therapy to capitalize on the high replication stress of tumors. Here, we review the current body of evidence regarding the role of replication stress in tumor progression and discuss potential means of enhancing tumor radiosensitivity by targeting the replication stress response. We offer new insights into the possibility of combining radiation therapy with replication stress drugs for clinical use.

Abstract 3065: Establishment and characterization of a platform of endometrial cancer organoids

Background: Endometrial cancer is the most commonly diagnosed gynecologic cancer in the US; the incidence is rising, and survival rates for this cancer are decreasing. There is a paucity of effective treatment for recurrent endometrial cancer, especially high grade endometrial cancers (HGEC) which include serous, carcinosarcoma, endometrioid, and clear cell histologies. Models that mimic the clinical and molecular characteristics of HGEC are lacking. To support the development of next generation therapeutics for endometrial cancer, we report on the establishment of 3D endometrial patient-derived organoids (PDOs) from HGEC.

Methods: 26 Tumors from 21 different patients with HGEC (Serous, Carcinosarcoma, Clear Cell and High-grade Endometrioid subtypes) who underwent surgical resection (n= 13), biopsy (n = 7), paracentesis (n = 3) or thoracentesis (n = 3) were passaged as 3D organoid cultures in Matrigel in an optimized media. Robust models (defined by average days to passage <14 days) were viably banked. 3 frozen models were also thawed and re-cultured to assess the viability post freezing. PDOs were collected for H&E staining and their histology was compared to the original diagnosis. DNA replication rate and the effect of replication stress on organoid growth were assessed by the DNA Fiber Assay and immunofluorescence (IF). Finally, an established clear cell endometrial cancer organoid model was engrafted in mice to generate a Patient-Derived Xenograft (PDX) model.

Results: Endometrial PDOs were successfully developed from 19 of 26 original samples for an overall success rate of 73.1%. Successful PDOs were developed from multiple histologies, including 8 carcinosarcoma, 6 uterine serous, 2 endometrioid, 2 clear cell and 1 mixed uterine serous and endometrioid. Though biopsy samples had initially fewer viable cells, our overall success rate was similar at 85.7% compared to 84.6% for surgical resections and higher than 66.7% for paracenteses. Samples obtained via thoracentesis did not form PDOs. Endometrial PDOs were histologically validated to match the primary patient tumor. Freeze thawing had no effect on morphology and growth characteristics. DNA fiber assays could be successfully conducted in PDOs, with a reduction in replication rate observed in PDO models treated with ATR or WEE1 inhibitors, with concurrent increase in y-H2AX and decrease in pRPA2 observed by IF. We also successfully generated a validated PDX model from organoids. Studies to determine molecular fidelity between the original patient tumor and established organoids are ongoing.

Conclusions: We describe the successful establishment of 19 endometrial PDO models which retain original tumor morphology and demonstrate sensitivity to drug-induced DNA damage. 3D endometrial organoids can therefore be used for further target discovery and validation as well as biomarker studies to advance targeted therapies for high-grade endometrial cancer.

Citation Format: Aisha L. Saldanha, Ha V. Vo, Kevin Vasquez, Kenneth Ngo, Shrabasti Roychoudhury, Carina Feeney, Courtney H. Qi, Swati Narayan, Jennifer D. Curtis, Prafulla C. Gokhale, Dipanjan Chowdhury, Cloud P. Paweletz, Marisa R. Nucci, Ursula A. Matulonis, Elena Ivanova, Joyce F. Liu. Establishment and characterization of a platform of endometrial cancer organoids [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 3065.

OP0052 THE EFFECT OF TOFACITINIB ON RESIDUAL PAIN IN PATIENTS WITH RHEUMATOID ARTHRITIS AND PSORIATIC ARTHRITIS WITH COMPLETE CONTROL OF INFLAMMATION

Background

Residual pain often remains in patients (pts) with rheumatoid arthritis (RA) and psoriatic arthritis (PsA) who achieve low disease activity or remission.1,2 Tofacitinib is an oral JAK inhibitor for the treatment of RA and PsA. A descriptive analysis showed that tofacitinib may have a beneficial effect on residual pain in pts with PsA with abrogated inflammation.3

Objectives

To assess efficacy of tofacitinib, adalimumab (ADA) and placebo (PBO) on residual pain in pts with RA and PsA with abrogated inflammation, using a network meta-analysis (NMA).

Methods

Data were pooled from 9 randomised clinical trials of pts with RA (NCT00960440/NCT00847613/NCT00814307/NCT00856544/NCT00853385/NCT01039688/NCT02187055) or PsA (NCT01877668/NCT01882439). This analysis included pts who received ≥1 dose of tofacitinib 5 mg twice daily (BID), ADA 40 mg once every 2 weeks or PBO with background therapy, and had abrogated inflammation (swollen joint count [SJC] = 0 and C-reactive protein [CRP] <6 mg/L) at Month (M)3. ADA was included in NCT00853385/NCT02187055/NCT01877668; NCT02187055 performed tofacitinib/ADA non-inferiority/superiority comparisons. Primary outcome was pt assessment of Pain (visual analogue scale [VAS] 0 [no pain] – 100 mm [most severe pain]) at M3; scores were summarised descriptively; treatment comparisons were assessed by Bayesian NMA on individual pt-level data, accounting for within-trial imbalances and treatment effect modifiers.

Results

Abrogated inflammation at M3 was achieved in 14.1% (328/2330), 14.9% (87/585) and 3.0% (20/673) of RA and 22.7% (54/238), 29.2% (31/106) and 12.7% (30/236) of PsA pts receiving tofacitinib, ADA and PBO, respectively. RA and PsA pts receiving tofacitinib/ADA had higher CRP vs pts receiving PBO. RA pts receiving tofacitinib/ADA had lower SJC and longer disease duration vs pts receiving PBO. PsA pts receiving tofacitinib had a longer disease duration and higher Pain VAS vs pts receiving ADA/PBO. In both groups, a lower % of female pts received tofacitinib/ADA vs PBO (Table 1). Observed median (Q1; Q3) values for Pain VAS at M3 were 17.0 (6.0; 31.0), 19.0 (7.0; 31.0) and 33.5 (7.0; 48.0) in RA and 24.0 (8.0; 44.0), 21.0 (9.0; 49.0) and 27.0 (8.0; 52.0) in PsA pts treated with tofacitinib, ADA or PBO, respectively. Differences between active treatments and PBO were less prominent in PsA vs RA pts, per posterior probability values (Fig).

Table 1.

Demographics and baseline characteristics of pts with abrogated inflammation at M3

RAPSATofacitinib 5 mg BID (N=328)ADAa 40 mg Q2W (N=87)PBO(N=20)Tofacitinib 5 mg BID (N=54)ADAa 40 mg Q2W (N=31)PBO(N=30)Age, yrs, mean (SD)50.7(12.8)49.2(13.9)44.6(9.9)51.1(11.7)47.4(11.6)49.7(11.6)Female, %79.077.090.044.435.570.0Weight, kg, mean (SD)68.9(16.9)72.5(21.8)71.4(25.0)89.1(22.7)83.2(19.0)76.7(15.7)Disease duration, yrs, median (Q1; Q3)4.8(1.4; 9.5)5.8(2.4; 11.1)2.6(1.7; 8.5)7.8(4.0; 14.3)2.7(1.0; 6.0)4.3(2.7; 10.0)SJC, median(Q1; Q3)9.0(7.0; 14.0)8.0(6.0; 12.0)10.5(9.0; 19.5)6.0(4.0; 10.0)5.0(4.0; 8.0)5.0(4.0; 7.0)CRP, mg/L, median (Q1; Q3)8.0(3.6; 20.0)8.6(3.6; 15.7)3.9(1.4; 6.4)3.7(1.1; 9.2)3.6(1.2; 12.5)2.2(1.2; 4.5)Pain VAS, median (Q1; Q3)57.0(39.0; 72.7)52.5(35.0; 69.0)62.0(38.5; 67.0)58.0(51.0; 75.0)48.0(36.0; 65.0)48.5(21.0; 61.0)

aADA was included in NCT00853385/NCT02187055/NCT01877668; NCT02187055 performed tofacitinib/ADA non-inferiority/superiority comparisons.

N, number of pts; Q1, 1st quartile (25th percentile); Q2W, once every 2 weeks; Q3, 3rd quartile (75th percentile); SD, standard deviation.

Conclusion

In this NMA, pts with RA and PsA achieving abrogated inflammation with tofacitinib or ADA at M3 had greater residual pain reduction vs those receiving PBO. This may imply that tofacitinib/ADA have analgesic benefits beyond those related to inflammation reduction.

References

[1]Michaud et al. Arthritis Care Res 2021; 73: 1606-1616.

[2]Kilic et al. Rheumatol Int 2019; 39: 73-81.

[3]Dougados et al. Arthritis Rheumatol 2019; 71 (S10): Abs 1502.

Acknowledgements

Study sponsored by Pfizer Inc. Medical writing support was provided by Lewis Rodgers, CMC Connect, and funded by Pfizer Inc.

Disclosure of Interests

Maxime Dougados Consultant of: AbbVie, Eli Lilly, Gilead Sciences, Janssen, Merck, Novartis, Pfizer Inc and UCB, Grant/research support from: AbbVie, Eli Lilly, Gilead Sciences, Janssen, Merck, Novartis, Pfizer Inc and UCB, Peter C. Taylor Consultant of: AbbVie, Biogen, Bristol-Myers Squibb, Celltrion, Eli Lilly, Fresenius, Galapagos, Gilead Sciences, GlaxoSmithKline, Janssen, Nordic Pharma, Pfizer Inc, Roche, Sanofi and UCB, Grant/research support from: Celgene and Galapagos, Clifton Bingham Consultant of: AbbVie, Bristol-Myers Squibb, Gilead Sciences, Eli Lilly, Janssen, Pfizer Inc and Sanofi/Genzyme, Grant/research support from: Bristol-Myers Squibb, Lara Fallon Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Yves Brault Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Satrajit Roychoudhury Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Lisy Wang Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, Meriem Kessouri Shareholder of: Pfizer Inc, Employee of: Pfizer Inc.

Is there impact of the SARS-CoV-2 pandemic on steroidogenesis and fertility?

In December of 2019, several cases of unknown atypical respiratory diseases emerged in Wuhan, Hubei Province in China. After preliminary research, it was stated that the disease is transmittable between humans and was named COVID-19. Over the course of next months, it spread all over the world by air and sea transport and caused a global pandemic which affects life of everyone now-a-days. A large number of countries, have since been forced to take precautions such as curfews, lockdowns, wearing facemasks etc. Even with vaccines being produced in mass numbers, lack of targeted therapy continues to be a major problem. According to studies so far it seems that elderly people are more vulnerable to severe symptoms while children tend to by asymptomatic or have milder form the disease. In our review, we focused on gathering data about the virus itself, its characteristics, paths of transmission, and its effect on hormone production and secretion. In such, there is insufficient information in the literature worldwide, especially the ones that focus on the effect of COVID-19 on individual organs systems within the human body. Hence, the present evidence-based study focused on the possible effects of COVID-19 on adrenal gland and gonads i.e. on the process of steroidogenesis and fertility.

Ovarian steroid hormone secretion by human granulosa cells after supplementation of sambucus nigra l. extract

Beneficial effects of Sambucus nigra L. (black elder) as a traditional medicine have been associated with the phytoconstituents including polyphenols, terpenes and lectins. Various antioxidant rich natural products have also been implicated with improvement of reproductive health and fertility, however, the effect of Sambucus nigra on the ovarian cell functions has not been investigated yet. The objectives of the present study were to screen the polyphenols in the elderflower and elderberry extracts, and to examine the secretion activity of steroid hormones 17beta-estradiol and progesterone by human ovarian granulosa cells HGL5 after supplementation of the extracts at a concentration range of 12.5 to 100 microg.ml-1. Qualitative as well as quantitative screening of polyphenols by high-performance liquid chromatography with diode-array detector (HPLC-DAD) analysis revealed rutin to be the most abundant polyphenol in both elderflower and elderberry extracts. In culture, neither elderflower nor elderberry extract caused any significant impact (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. However, a dose-dependent stimulation of 17beta-estradiol release was detected by ELISA after supplementation of elderflower (at 50 microg.ml-1; p<0.01) and elderberry (at 100 microg.ml-1; p<0.05) extracts at higher doses used in the study. On the other hand, both elderflower and elderberry extracts stimulated the secretion of progesterone by HGL5 cells at a lower dose (12.5 microg.ml-1; p<0.05), as compared to control. Therefore, elderflower and elderberry extracts may have the potential to regulate steroidogenesis in ovarian cells.

Antioxidative effect of dietary flavonoid isoquercitrin on human ovarian granulosa cells HGL5 in vitro

This study aimed to examine the effect of dietary flavonoid isoquercitrin on ovarian granulosa cells using the immortalized human cell line HGL5. Cell viability, survival, apoptosis, release of steroid hormones 17beta-estradiol and progesterone, and human transforming growth factor-beta2 (TGF-beta2) and TGF-beta2 receptor as well as intracellular reactive oxygen species (ROS) generation were investigated after isoquercitrin treatment at the concentration range of 5-100 microg.ml-1. It did not cause any significant change (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. No significant change was observed (p>0.05) in the proportion of live, dead and apoptotic cells as revealed by apoptotic assay using flow cytometry. Similarly, the release of 17beta-estradiol, progesterone, TGF-beta2 and its receptor were not affected significantly (p>0.05) by isoquercitrin as detected by ELISA, in comparison to control. Except for the highest concentration of 100 microg.ml-1, which led to oxidative stress, isoquercitrin exhibited antioxidative activity at lower concentration used in the study (5, 10, 25, and 50 microg.ml-1) by hampering the production of intracellular ROS, in comparison to control, as detected by chemiluminescence assay (p<0.05). Findings of the present study indicate an existence of the antioxidative pathway that involves inhibition of intracellular ROS generation by isoquercitrin in human ovarian granulosa cells.

Immunotherapy for Alzheimer's Disease: Current Scenario and Future Perspectives

Alzheimer's disease (AD) is a global health concern owing to its complexity, which often poses a great challenge to the development of therapeutic approaches. No single theory has yet accounted for the various risk factors leading to the pathological and clinical manifestations of dementia-type AD. Therefore, treatment options targeting various molecules involved in the pathogenesis of the disease have been unsuccessful. However, the exploration of various immunotherapeutic avenues revitalizes hope after decades of disappointment. The hallmark of a good immunotherapeutic candidate is not only to remove amyloid plaques but also to slow cognitive decline. In line with this, both active and passive immunotherapy have shown success and limitations. Recent approval of aducanumab for the treatment of AD demonstrates how close passive immunotherapy is to being successful. However, several major bottlenecks still need to be resolved. This review outlines recent successes and challenges in the pursuit of an AD vaccine.

Human Adrenocortical Carcinoma (NCI-H295R) Cell Line as an In Vitro Cell Culture Model for Assessing the Impact of Iron on Steroidogenesis

The aim of this in vitro study was to examine the dose-dependent effects of iron as a potential endocrine disruptor in relation to the release of sexual steroid hormones by a human adrenocortical carcinoma (NCI-H295R) cell line. The cells were exposed to different concentrations (3.90, 62.50, 250, 500, 1000 μM) of FeSO4.7H2O and compared with the control group (culture medium without FeSO4.7H2O). Cell viability was measured by the metabolic activity assay. Quantification of sexual steroid production was performed by enzyme-linked immunosorbent assay. Following 48 h culture of the cells in the presence of FeSO4.7H2O, significantly (P < 0.001) increased production of progesterone was observed at the lowest concentration (3.90 μM) of FeSO4.7H2O, whereas the lowest release of progesterone by NCIH295R cells was noted after addition of 1000 μM of FeSO4.7H2O, which did not elicit cytotoxic action (P > 0.05). Testosterone production was substantially increased at the concentrations ≤ 62.50 μM of FeSO4.7H2O. Lower levels of testosterone were recorded in the groups with higher concentrations (≥ 250 μM) of FeSO4.7H2O (P > 0.05). The presented data suggest that iron has no endocrine disruptive effect on the release of sexual steroid hormones, but its toxicity may be reflected at other points of the steroidogenesis pathway.

Red panda: a novel method for detecting variants in single-cell RNA sequencing

BACKGROUND

Single-cell sequencing enables us to better understand genetic diseases, such as cancer or autoimmune disorders, which are often affected by changes in rare cells. Currently, no existing software is aimed at identifying single nucleotide variations or micro (1-50 bp) insertions and deletions in single-cell RNA sequencing (scRNA-seq) data. Generating high-quality variant data is vital to the study of the aforementioned diseases, among others.

RESULTS

In this study, we report the design and implementation of Red Panda, a novel method to accurately identify variants in scRNA-seq data. Variants were called on scRNA-seq data from human articular chondrocytes, mouse embryonic fibroblasts (MEFs), and simulated data stemming from the MEF alignments. Red Panda had the highest Positive Predictive Value at 45.0%, while other tools-FreeBayes, GATK HaplotypeCaller, GATK UnifiedGenotyper, Monovar, and Platypus-ranged from 5.8-41.53%. From the simulated data, Red Panda had the highest sensitivity at 72.44%.

CONCLUSIONS

We show that our method provides a novel and improved mechanism to identify variants in scRNA-seq as compared to currently existing software. However, methods for identification of genomic variants using scRNA-seq data can be still improved.

In vitro assessment of the impact of nickel on the viability and steroidogenesis in the human adrenocortical carcinoma (NCI-H295R) cell line

Nickel is a ubiquitous environmental pollutant, which has various effects on reproductive endocrinology. In this study, human adrenocortical carcinoma (NCI-H295R) cell line was used as an in vitro biological model to study the effect of nickel chloride (NiCl2) on the viability and steroidogenesis. The cells were exposed to different concentrations (3.90; 7.80; 15.60; 31.20; 62.50; 125; 250 and 500 microM) of NiCl2 and compared with control group (culture medium without NiCl2). The cell viability was measured by the metabolic activity assay. Production of sexual steroid hormones was quantified by enzyme linked immunosorbent assay. Following 48 h culture of the cells in the presence of NiCl2 a dose-dependent depletion of progesterone release was observed even at the lower concentrations. In fact, lower levels of progesterone were detected in groups with higher doses (>/=125 microM) of NiCl2 (P<0.01), which also elicited cytotoxic action. A more prominent decrease in testosterone production (P<0.01) was also noted in comparison to that of progesterone. On the other hand, the release of 17beta-estradiol was substantially increased at low concentrations (3.90 to 62.50 microM) of NiCl2. The cell viability remained relatively unaltered up to 125 microM (P>0.05) and slightly decreased from 250 microM of NiCl2 (P<0.05). Our results indicate endocrine disruptive effect of NiCl2 on the release of progesterone and testosterone in the NCI-H295R cell line. Although no detrimental effect of NiCl2 (</=62.50 microM) could be found on 17beta-estradiol production, its toxicity may reflect at other points of the steroidogenic pathway.

Pan-Cancer Analysis Reveals the Diverse Landscape of Novel Sense and Antisense Fusion Transcripts

Gene fusions that contribute to oncogenicity can be explored for identifying cancer biomarkers and potential drug targets. To investigate the nature and distribution of fusion transcripts in cancer, we examined the transcriptome data of about 9,000 primary tumors from 33 different cancers in TCGA (The Cancer Genome Atlas) along with cell line data from CCLE (Cancer Cell Line Encyclopedia) using ChimeRScope, a novel fusion detection algorithm. We identified several fusions with sense (canonical, 39%) or antisense (non-canonical, 61%) transcripts recurrent across cancers. The majority of the recurrent non-canonical fusions found in our study are novel, unexplored, and exhibited highly variable profiles across cancers, with breast cancer and glioblastoma having the highest and lowest rates, respectively. Overall, 4,344 recurrent fusions were identified from TCGA in this study, of which 70% were novel. Additional analysis of 802 tumor-derived cell line transcriptome data across 20 cancers revealed significant variability in recurrent fusion profiles between primary tumors and corresponding cell lines. A subset of canonical and non-canonical fusions was validated by examining the structural variation evidence in whole-genome sequencing (WGS) data or by Sanger sequencing of fusion junctions. Several recurrent fusion genes identified in our study show promise for drug repurposing in basket trials and present opportunities for mechanistic studies.

Targeting Histone Chaperone FACT Complex Overcomes 5-Fluorouracil Resistance in Colon Cancer

Fluorouracil (5-FU) remains a first-line chemotherapeutic agent for colorectal cancer. However, a subset of colorectal cancer patients who have defective mismatch-repair (dMMR) pathway show resistance to 5-FU. Here, we demonstrate that the efficacy of 5-FU in dMMR colorectal cancer cells is largely dependent on the DNA base excision repair (BER) pathway. Downregulation of APE1, a key enzyme in the BER pathway, decreases IC₅₀ of 5-FU in dMMR colorectal cancer cells by 10-fold. Furthermore, we discover that the facilitates chromatin transcription (FACT) complex facilitates 5-FU repair in DNA via promoting the recruitment and acetylation of APE1 (AcAPE1) to damage sites in chromatin. Downregulation of FACT affects 5-FU damage repair in DNA and sensitizes dMMR colorectal cancer cells to 5-FU. Targeting the FACT complex with curaxins, a class of small molecules, significantly improves the 5-FU efficacy in dMMR colorectal cancer in vitro (∼50-fold decrease in IC₅₀) and in vivo xenograft models. We show that primary tumor tissues of colorectal cancer patients have higher FACT and AcAPE1 levels compared with adjacent nontumor tissues. Additionally, there is a strong clinical correlation of FACT and AcAPE1 levels with colorectal cancer patients' response to chemotherapy. Together, our study demonstrates that targeting FACT with curaxins is a promising strategy to overcome 5-FU resistance in dMMR colorectal cancer patients.

Abstract 4495: Role of base excision repair (BER) pathway in regulation of KRAS expression in pancreatic cancer

Activating mutations in KRAS proto-oncogene, a signature event driving the development, progression and therapeutic resistance of pancreatic ductal adenocarcinoma (PDAC), remains undruggable. The occurrence of guanine oxidation (8-oxoguanine) in the KRAS promoter and up-regulation of KRAS gene transcription under oxidative stress has been shown to be associated with KRAS expression and cancer development and progression. However, the molecular mechanism by which 8-oxoguanine damage regulates KRAS expression is largely unknown. Here, we show that the base excision repair (BER) pathway, a fundamental DNA damage repair pathway that processes most of the endogenous damages including oxidative base damage is involved in regulation of KRAS expression and survival of PDAC. We show that Apurinic/apyrimidinic endonuclease (APE1), a key enzyme of the BER pathway, is highly elevated in pancreatic cancer tissue samples. To elucidate the role of active BER pathway in the regulation of KRAS expression, we used real-time PCR (RT-PCR) analysis. Inflicting cells with oxidative damage using glucose oxidase increased KRAS gene expression in control cells but not in APE1 downregulated cells. ChIP assay showed enhanced occupancy of APE1 in KRAS promoter upon oxidative stress. Consistent with this, using synthetic oligonucleotide containing the KRAS promoter region, we showed that APE1 could bind and cleave AP site in KRAS promoter. Further, ChIP-qPCR analysis showed decreased occupancy of MAZ, a transcription factor, to the KRAS promoter in APE1 downregulated cells. Down-regulation of APE1 also resulted in decreased KRAS expression and increased sensitivity of pancreatic cancer cells to routinely used chemotherapeutic agents such as Gemcitabine, 5-Fluorouracil, Oxaliplatin, etc., suggesting that targeting APE1 and in turn, BER can sensitize pancreatic cancer cells. Our study suggests that BER pathway or APE1 plays a significant role in the tumor-selective regulation of gene expression and sensitization of cancer cells to chemotherapy, and supports the further investigation of novel treatments that target this pathway for cancer therapy.

Citation Format: Suravi Pramanik, Shrabasti Roychoudhury, Hannah Harris, Heyu Song, Kishor K. Bhakat. Role of base excision repair (BER) pathway in regulation of KRAS expression in pancreatic 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 4495.

Coenzyme Q10 ameliorates cadmium induced reproductive toxicity in male rats

This study aimed at investigating the protective role of CoQ10 against cadmium (Cd)-induced reproductive toxicity in male rats. Adult male Wistar rats were exposed to an acute dose of Cd (25 mg/kg bwt; Cd group), Cd+CoQ10 (25 mg/kg bwt Cd+10 mg CoQ10; Cd-Q10 group) and distilled water (control) in vivo for 15 consecutive days and semen quality was assessed. A significant reduction was noted in sperm concentration, progressive motility, morphology and DNA integrity in both Cd- and Cd-Q10 groups in comparison to control indicating Cd-induced testicular lipid per oxidation (LPO) and decline in indigenous antioxidant defense system as measured by total antioxidant capacity (TAC) (p<0.05). However, simultaneous co-administration of CoQ10 along with Cd (Cd-Q10 group) was able to improve sperm concentration, motility, progressive motility, morphology, DNA integrity, and testicular TAC as well as lower LPO compared to Cd group (p<0.05). Results indicate that used dose of CoQ10 is capable of moderately ameliorating reproductive toxicity of Cd by improving semen quality and reducing testicular oxidative stress.

Abstract 2819: Targeting histone chaperone FACT complex sensitizes medulloblastoma cells to chemo and radiation therapy

Medulloblastoma (MB) is the most common malignant brain tumor in children. Post-surgical radiotherapy in combination with adjuvant chemotherapy are considered as standard treatment of care for MB. However, this long-term treatment often leads to harmful neurologic effects to the developing brain in children. Therefore, identification of novel therapeutic target to increase efficacy and reduce toxicity in MB represent an unmet clinical need.

Apurinic/apyrimidinic (AP)-endonuclease (APE1) plays a central role in the base excision repair (BER) pathway by repairing AP sites and single-strand breaks, the downstream cytotoxic BER intermediate that occurs following radiation and chemotherapy. Elevated levels of APE1 or its activity has been shown to be associated with response to radiation and chemotherapy in MB. However, how APE1 repairs AP sites in the context of nucleosome in cells and how APE1-dependnt BER pathway can be manipulated to increase the therapeutic efficacy of chemo and radiation therapy remain an open question. We have recently shown that APE1 is acetylated (AcAPE1) at AP site damage in chromatin by p300 and that acetylation enhances AP-endonuclease activity of APE1. Here, we show that APE1 interacts with the nucleosome remodeling histone chaperone Facilitates of Chromatin Transcription (FACT) complex (a heterodimer of SSRP1 and SPT16 proteins) and that FACT complex is required for binding and acetylation of APE1 at AP site damages in highly aggressive MB cell lines HD-MB03 and ONS-76. Furthermore, we have mapped genome-wide binding of AcAPE1 in HDMB cells and our ChIP-seq data analysis revealed ~68154 (p&lt;.001) AcAPE1 binding predominantly located in the transcribed gene regions corresponding to 16370 genes. We aligned ChIP-Seq with RNA-Seq of HD-MB03 cells and found a significant (p&lt;0.0001) correlation of AcAPE1 binding with gene expression. Furthermore, our data show that inhibition of FACT with small molecule inhibitor CBL0137/curaxin, reduces SSRP1 and SPT16 levels from soluble fraction and trap them in chromatin. We found that CBL0137/curaxin treatment results in inhibition of APE1 acetylation, and that MB cells cannot repair DNA damages in the presence of FACT inhibitor. FACT has been shown to play an important role in removal of cisplatin-induced DNA adducts via nucleotide excision repair pathway (NER). Of importance, downregulation of APE1 levels or inhibition of FACT with CBL0137/curaxin sensitizes a panel of highly aggressive MB cell lines to cisplatin and alkylating drug temozolomide.

Together, our study suggest that co-suppression of both BER and NER pathways via targeting FACT complex can greatly sensitize MB tumors to chemo and radiation therapy. A major implication of our studies is that combination of curaxin with low dose of cisplatin may have considerable therapeutic potential to improve efficacy and reduce cytotoxic side effects of cisplatin to MB patients.

Citation Format: Sutapa Ray, Heyu Song, Shrabasti Roychoudhury, Pranjal Biswas, Sutapa Ray, Kishor Bhakat. Targeting histone chaperone FACT complex sensitizes medulloblastoma cells to chemo and radiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2819.

Abstract 348: Targeting histone chaperone FACT complex and APE1 sensitizes colon cancer cells to chemotherapy

Apurinic/apyrimidinic (AP) sites are one of the most common types of DNA damage that occur spontaneously and following chemotherapy. Human AP-endonuclease (APE1) is primarily responsible for initiating the repair of AP sites via the highly coordinated DNA base excision repair (BER) pathway. Although the repair of AP sites by APE1 utilizing naked DNA or nucleosomal DNA substrate has been extensively investigated in vitro, till to date, how APE1 repairs AP sites in chromatin in cells via BER pathway remains largely unknown. Chromatin remodeling histone chaperone FACT (facilitates chromatin transcription) complex has been previously shown to mediate nucleosome disruption which allows DNA repair proteins to gain access to damage sites. Its involvement in nucleotide excision repair (NER) pathway has been demonstrated. However, the role of FACT in BER remains unclear. Our lab has recently found that APE1 is acetylated at AP sites damage in chromatin and acetylation enhances the DNA repair activity of APE1. Here, we show that APE1 interacts with histone chaperone complex FACT. Subsequently, we confirmed the interaction of APE1 with FACT complex by Co-IP and immunofluorescence (IF) and found that both subunit of FACT complex, SPT16 and SSRP1, interact with APE1 in the nucleus and in chromatin. By Western blot (WB), IF and co-IP, we found enhanced interaction upon induction of DNA damage. To understand the functional importance of FACT, we downregulated its levels using siRNA and noted increased cell sensitivity upon damage by using MTT and colony formation. The number of AP sites in the genome increased significantly upon FACT knockdown. FRAP data demonstrated increased APE1 turnover time in damage sites after FACT knock-down suggesting the role of FACT in nucleosome disruption in facilitating the APE1 function in BER pathway. Decreasing FACT level led to reduced acetylation level of APE1 at damage sites and impaired DNA repair as evident by comet assay. Additionally, we found elevated levels of AcAPE1 and FACT in colon cancer tissues and multiple cell lines as compared to normal adjacent tissues and cells. We used curaxin which blocks the function of FACT and found increased cell sensitivity to various chemotherapeutic agents in multiple colon cancer cell lines. In nude mice xenograft, combination of curaxin and 5-FU group slowed the growth of tumor to the largest extent as compared to 5-FU and curaxin groups. Together our study suggests that FACT is required for APE1 to gain access to AP sites in the context of chromatin. Interruption of APE1 and FACT interaction exhibits synergistic effect on cell viability and proliferation upon DNA damage with chemotherapeutic drugs. We demonstrate targeting both FACT and BER pathway together as a novel strategy for chemosensitization of colon cancer cells.

Citation Format: Heyu Song, Shrabasti Roychoudhury, Pranjal Biswas, Jiping Zeng, Kishor Bhakat. Targeting histone chaperone FACT complex and APE1 sensitizes colon cancer cells to chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 348.

Elevated level of acetylation of APE1 in tumor cells modulates DNA damage repair

Apurinic/apyrimidinic (AP) sites are frequently generated in the genome by spontaneous depurination/depyrimidination or after removal of oxidized/modified bases by DNA glycosylases during the base excision repair (BER) pathway. Unrepaired AP sites are mutagenic and block DNA replication and transcription. The primary enzyme to repair AP sites in mammalian cells is AP endonuclease (APE1), which plays a key role in this repair pathway. Although overexpression of APE1 in diverse cancer types and its association with chemotherapeutic resistance are well documented, alteration of posttranslational modification of APE1 and modulation of its functions during tumorigenesis are largely unknown. Here, we show that both classical histone deacetylase HDAC1 and NAD⁺-dependent deacetylase SIRT1 regulate acetylation level of APE1 and acetylation of APE1 enhances its AP-endonuclease activity both in vitro and in cells. Modulation of APE1 acetylation level in cells alters AP site repair capacity of the cell extracts in vitro. Primary tumor tissues of diverse cancer types have higher level of acetylated APE1 (AcAPE1) compared to adjacent non-tumor tissue and exhibit enhanced AP site repair capacity. Importantly, in the absence of APE1 acetylation, cells accumulate AP sites in the genome and show increased sensitivity to DNA damaging agents. Together, our study demonstrates that elevation of acetylation level of APE1 in tumor could be a novel mechanism by which cells handle the elevated levels of DNA damages in response to genotoxic stress and maintain sustained proliferation.

Suppression of STAT3 NH2 -terminal domain chemosensitizes medulloblastoma cells by activation of protein inhibitor of activated STAT3 via de-repression by microRNA-21

Medulloblastoma (MB) is a malignant pediatric brain tumor with poor prognosis. Signal transducers and activators of transcription-3 (STAT3) is constitutively activated in MB where it functions as an oncoprotein, mediating cancer progression and metastasis. Here, we have delineated the functional role of activated STAT3 in MB, by using a cell permeable STAT3-NH₂ terminal domain inhibitor (S3-NTDi) that specifically perturbs the structure/function of STAT3. We have implemented several biochemical experiments using human MB tumor microarray (TMA) and pediatric MB cell lines, derived from high-risk SHH-TP53-mutated and MYC-amplified Non-WNT/SHH tumors. Treatment of MB cells with S3-NTDi leads to growth inhibition, cell cycle arrest, and apoptosis. S3-NTDi downregulated expression of STAT3 target genes, delayed migration of MB cells, attenuated epithelial-mesenchymal transition (EMT) marker expressions and reduced cancer stem-cell associated protein expressions in MB-spheres. To elucidate mechanisms, we showed that S3-NTDi induce expression of pro-apoptotic gene, C/EBP-homologous protein (CHOP), and decrease association of STAT3 to the proximal promoter of CCND1 and BCL2. Of note, S3-NTDi downregulated microRNA-21, which in turn, de-repressed Protein Inhibitor of Activated STAT3 (PIAS3), a negative regulator of STAT3 signaling pathway. Furthermore, combination therapy with S3-NTDi and cisplatin significantly decreased highly aggressive MYC-amplified MB cell growth and induced apoptosis by downregulating STAT3 regulated proliferation and anti-apoptotic gene expression. Together, our results revealed an important role of STAT3 in regulating MB pathogenesis. Disruption of this pathway with S3-NTDi, therefore, may serves as a promising candidate for targeted MB therapy by enhancing chemosensitivity of MB cells and potentially improving outcomes in high-risk patients.

Human sperm handling in intracytoplasmic sperm injection processes: In vitro studies on mouse oocyte activation, embryo development competence and sperm oxidation-reduction potential

Polyvinylpyrrolidone (PVP) and hyaluronic acid (HA) are routinely used in handling spermatozoa for intracytoplasmic sperm injection (ICSI). As there are still concerns about possible adverse effects on the embryo, this study investigated sperm handling in a mouse ICSI model to (i) evaluate oocyte activation after injection of spermatozoa selected for rotational or linear motion in PVP; (ii) assess the effect of sperm selection in PVP, HA and medium on oocyte activation; (iii) examine the effects of PVP and HA on parthenogenetic oocyte activation and embryo development; and (iv) assess the oxidation-reduction potential (ORP) of spermatozoa exposed to PVP, HA or medium. Oocyte activation was higher when spermatozoa exhibited rotational motion rather than linear motion (79% vs. 52%; p = .05). There was no difference in oocyte activation and embryo development after parthenogenetic oocyte activation after sperm injection using PVP, HA or medium-incubated spermatozoa. PVP-selected spermatozoa exhibited lower (p < .0001) ORP levels than using HA. Thus, results indicate that the sperm handling method and the type of medium used impact ICSI outcomes. Overall, sperm incubation in PVP, HA and medium yields similar outcomes with regard to oocyte activation and embryo development. However, PVP provides more antioxidative protection than HA and should therefore be preferred for sperm manipulation.

Ovarian steroid hormone secretion activity examined after supplementation of green tea extract

This study aimed at examining the secretion activity of steroid hormones progesterone and 17beta-estradiol by porcine ovarian granulosa cells after addition of green tea extract. Granulosa cells were incubated with green tea extract (at doses of 0.01, 0.1, 1, 10 and 100 microg.ml(-1). Another set of cells were incubated with green tea extract at the above doses along with additional supplementation of follicle stimulating hormone (FSH) at 10 microg.ml(-1). Release of hormones by granulosa cells was assessed by EIA after 24 h exposure. Secretion of steroid hormones was not affected either by green tea extract alone or after FSH supplementation with green tea extract. Results indicate that ovarian steroidogenesis is not affected by green tea under conditions used in the experiment.

Abstract 1414: Chromatin remodeling histone chaperone FACT complex modulates AP site damage repair in chromatin and sensitizes cancer cells to chemotherapeutic drugs

Recognition and repair of DNA lesions in the genome are critical for maintaining genomic stability and reducing the generation of mutations that lead to cancer development. The most frequently formed DNA lesion in the genome is the apurinic/apyrimidinic (AP) site which is mutagenic and blocks transcription and replication. The primary enzyme to repair AP sites in mammalian cells is the AP endonuclease (APE1), which often overexpresses in diverse cancer types and its overexpression is associated with patients’ resistance to chemotherapeutic drugs. The repair of AP sites by APE1 through the Base Excision Repair (BER) pathway is extensively investigated in vitro. However, how AP site is recognized by APE1 in the context of highly complex nucleosome structure in chromatin is unknown. Because DNA is packaged tightly in nucleosome, the ability of repair proteins to access sites of DNA damage and facilitates repair of the damage requires chromatin remodeling activities. Here, we show that APE1 interacts with chromatin remodeling histone chaperone complex, FACT (facilitates of chromatin transcription) via its N-terminal domain in cells. By immunoprecipitation of endogenous APE1 from chromatin fraction and separation of protein bands in SDS-PAGE followed by MALDI-TOF-TOF analysis, we have identified both subunits (SPT16 & SSRP1) of FACT as the prominent APE1 interacting partners. Subsequently, we confirmed the interaction of APE1 with FACT complex by Co-IP and immunofluorescence analysis and found that both SPT16 and SSRP1 interact with APE1 in the nucleus and in chromatin. Interestingly, we found rapid eviction of histones with concomitant degradation of FACT complex upon induction of DNA damages. Downregulation of FACT complex abrogates the nucleosome eviction, the recruitment of repair protein APE1 in chromatin and the repair of AP sites, demonstrating the functional importance of nucleosomes disruption in BER pathway and identifying chromatin remodeling protein required for the process. Notably, knock-down of FACT showed increased sensitivity of cancer cells to many chemotherapeutic drugs. We also found that FACT down-regulated cells have much higher accumulation of AP site damages in the genome compared to control cells. Our study revealed a key role of nucleosome remodeling complex FACT in DNA damage repair in BER pathway. This study also suggests that histone chaperone complex could be a potential target for enhancing sensitivity of tumor cells to chemotherapy.

Citation Format: Heyu Song, Shrabasti Roychoudhury, Dan Feng, Kishor Bhakat. Chromatin remodeling histone chaperone FACT complex modulates AP site damage repair in chromatin and sensitizes cancer cells to chemotherapeutic drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1414. doi:10.1158/1538-7445.AM2017-1414

MiRNA199a-3p suppresses tumor growth, migration, invasion and angiogenesis in hepatocellular carcinoma by targeting VEGFA, VEGFR1, VEGFR2, HGF and MMP2

Increasing significance of tumor-stromal interaction in development and progression of cancer implies that signaling molecules in the tumor microenvironment (TME) might be the effective therapeutic targets for hepatocellular carcinoma (HCC). Here, the role of microRNA miR-199a-3p in the regulation of TME and development of HCC has been investigated by several in vitro and in vivo assays. Expression of miR-199a-3p was observed significantly low in HCC tissues and its overexpression remarkably inhibited in vivo tumor growth and metastasis to lung in NOD-SCID mice. In vitro restoration of miR-199a-3p expression either in endothelial cells (ECs) or in cancer cells (CACs) significantly diminished migration of ECs in co-culture assay. Again incubation of miR-199a-3p transfected ECs with either conditioned media (CM) of CACs or recombinant VEGF has reduced tube formation, in ECs and it was also dropped upon growth in CM of either anti-VEGF antibody-treated or miR-199a-3p-transfected CACs. In addition, bioinformatics and luciferase-reporter assays revealed that miR-199a-3p inhibited VEGF secretion from CACs and VEGFR1 and VEGFR2 expression on ECs and thus restricted cross talk between CACs and ECs. Again, restoration of miR-199a-3p in hepatic stellate cells (HSCs) reduced migration and invasion of CACs in co-culture assay, while it was enhanced by the overexpression of HGF suggesting miR-199a-3p has hindered HSC-CACs cross talk probably by inhibiting HGF and regulating matrix metalloproteinase MMP2, which were found as targets of miR-199a-3p subsequently by luciferase-reporter assay and gelatin zymography, respectively. Thus, these findings collectively highlight that miR-199a-3p restricts metastasis, invasion and angiogenesis in HCC and hence it may be considered as one of the powerful effective therapeutics for management of HCC patients.

Incidence of Cryptosporidium andersoni in diarrheal patients from southern Assam, India: a molecular approach

The distribution and public health significance of Cryptosporidium species and genotypes in humans and bovine differ across geographical areas. Cryptosporidium species causes a disease known as cryptosporidiosis in humans and animals. To characterize the prevalence of cryptosporidiosis in humans in southern Assam, India, stool samples (n = 1119) of diarrhea patients were collected from different hospitals and from the community during the period January 2014 to July 2016. Fecal smears were examined microscopically for Cryptosporidium species using modified acid fast staining and were screened to ascertain the presence of Cryptosporidium antigen by enzyme-linked immunosorbent assay (ELISA). The genomic DNA of positive fecal samples were analyzed by nested polymerase chain reaction (PCR), which were subsequently genotyped by PCR-restriction fragment length polymorphism (RFLP), based on small subunit (SSU) 18S rRNA. It was found that the prevalence of Cryptosporidium spp. was high during the monsoon season. The average infection rate of Cryptosporidium spp. was found to be 2.4% (27/1119) microscopically. When subjected to nested PCR using amplification of the 18S rRNA gene, Cryptosporidium was found to be 8.57% (98/1119). Based on the 18S rRNA gene, two Cryptosporidium spp., namely Cryptosporidium andersoni (6.97%: 78/1119) and Cryptosporidium parvum (1.7%: 20/1119), were identified. Cryptosporidium andersoni infections were found to be of either zoonotic or anthroponotic origin. The prevalence was statistically significant (p = 0.03, R² = 0.042) considering age, gender, and cast.

Occupational benzene exposure from vehicular sources in India and its effect on hematology, lymphocyte subsets and platelet P-selectin expression

Benzene exposure from vehicular sources and its health impact are relatively unexplored in India. We have investigated in this study hematology and lymphocyte subsets of 25 petrol pump attendants, 25 automobile service station workers and 35 controls matched for age, sex and socioeconomic conditions. The participants were non-smoking males of Kolkata (former Calcutta) in eastern India. Compared with controls, the workers had 3.8- times more trans,trans-muconic acid in urine, suggesting higher level of benzene exposure. The exposed subjects had decreased erythrocyte, hemoglobin, lymphocyte and platelet levels, but increased neutrophil, band cells, RBC aniso-poikilocytosis and target cells. In addition, CD4+, CD8+ and CD19+ cells were decreased by 37, 20 and 47% respectively, but CD 16+ 56+ NK cells were increased by 20%. P-selectin expression on platelet surface of the workers was significantly elevated ( P < 0.05), indicating upregulation of platelet activity. In summary, the study revealed high level of benzene exposure from vehicular sources in India, and the exposed subjects had hematological and immunological alterations. Toxicology and Industrial Health 2007; 23: 167—175.

DNA damage-induced ephrin-B2 reverse signaling promotes chemoresistance and drives EMT in colorectal carcinoma harboring mutant p53

Mutation in the TP53 gene positively correlates with increased incidence of chemoresistance in different cancers. In this study, we investigated the mechanism of chemoresistance and epithelial-to-mesenchymal transition (EMT) in colorectal cancer involving the gain-of-function (GOF) mutant p53/ephrin-B2 signaling axis. Bioinformatic analysis of the NCI-60 data set and subsequent hub prediction identified EFNB2 as a possible GOF mutant p53 target gene, responsible for chemoresistance. We show that the mutant p53-NF-Y complex transcriptionally upregulates EFNB2 expression in response to DNA damage. Moreover, the acetylated form of mutant p53 protein is recruited on the EFNB2 promoter and positively regulates its expression in conjunction with coactivator p300. In vitro cell line and in vivo nude mice data show that EFNB2 silencing restores chemosensitivity in mutant p53-harboring tumors. In addition, we observed high expression of EFNB2 in patients having neoadjuvant non-responder colorectal carcinoma compared with those having responder version of the disease. In the course of deciphering the drug resistance mechanism, we also show that ephrin-B2 reverse signaling induces ABCG2 expression after drug treatment that involves JNK-c-Jun signaling in mutant p53 cells. Moreover, 5-fluorouracil-induced ephrin-B2 reverse signaling promotes tumorigenesis through the Src-ERK pathway, and drives EMT via the Src-FAK pathway. We thus conclude that targeting ephrin-B2 might enhance the therapeutic potential of DNA-damaging chemotherapeutic agents in mutant p53-bearing human tumors.

Possible intracellular regulators of female sexual maturation

Protein kinases, transcription factors and other apoptosis- and proliferation-related proteins can regulate reproduction, but their involvement in sexual maturation remains to be elucidated. The general aim of the in vivo and in vitro experiments with porcine ovarian granulosa cells was to identify possible intracellular regulators of female sexual maturation. For this purpose, proliferation (expression of proliferating cell nuclear antigen - PCNA, mitogen-activated protein kinases - ERK 1,2 related MAPK and cyclin B1), apoptosis (expression of the apoptotic protein Bax and apoptosis regulator Bcl-2 protein), expression of some protein kinases (cAMP dependent protein kinase - PKA, cGMP-dependent protein kinase - PKG, tyrosine kinase - TK) and cAMP responsive element binding protein 1 (CREB-1) was examined in granulosa cells isolated from ovaries of immature and mature gilts. Expression of PCNA, ERK1,2 related MAPK, cyclin B1, Bcl-2, Bax, PKA, CREB-1, TK and PKG in porcine granulosa cells were detected by immunocytochemistry. Sexual maturation was associated with significant increase in the expression of Bcl-2, Bax, PKA, CREB-1 and TK and with decrease in the expression of ERK1,2 related MAPK, cyclin B1 and PKG in granulosa cells. No significant difference in PCNA expression was noted. The present data obtained from in vitro study indicate that sexual maturation in females is influenced by puberty-related changes in porcine ovarian signaling substances: increase in Bcl-2, Bax, PKA, CREB-1, TK and decrease in ERK1,2 related MAPK, cyclin B1 and PKG. It suggests that these signaling molecules could be potential regulators of porcine sexual maturation.

Novel point and combo-mutations in the genome of hepatitis B virus-genotype D: characterization and impact on liver disease progression to hepatocellular carcinoma

Background

The contribution of chronic hepatitis B virus (HBV) infection in the pathogenesis of hepatocellular carcinoma (HCC) through progressive stages of liver fibrosis is exacerbated by the acquisition of naturally occurring mutations in its genome. This study has investigated the prevalence of single and combo mutations in the genome of HBV-genotype D from treatment naïve Indian patients of progressive liver disease stages and assessed their impact on the disease progression to HCC.

Methods

The mutation profile was determined from the sequence analysis of the full-length HBV genome and compared with the reference HBV sequences. SPSS 16.0 and R software were used to delineate their statistical significance in predicting HCC occurrence.

Results

Age was identified as associated risk factor for HCC development in chronic hepatitis B (CHB) patients (p≤0.01). Beyond the classical mutations in basal core promoter (BCP) (A1762T/G1764A) and precore (G1862T), persistence of progressively accumulated mutations in enhancer-I, surface, HBx and core were showed significant association to liver disease progression. BCP_T1753C, core_T147C, surface_L213I had contributed significantly in the disease progression to HCC (p<0.05) in HBeAg positive patients whereas precore_T1858C, core_I116L, core_P130Q and preS1_S98T in HBeAg negative patients. Furthermore, the effect of individual mutation was magnified by the combination with A1762T/G1764A in HCC pathogenesis. Multivariate risk analysis had confirmed that core_P130Q [OR 20.71, 95% CI (1.64–261.77), p = 0.019] in B cell epitope and core_T147C [OR 14.58, 95% CI (1.17–181.76), p = 0.037] in CTL epitope were two independent predictors of HCC in HBeAg positive and negative patients respectively.

Conclusions

Thus distinct pattern of mutations distributed across the entire HBV genome may be useful in predicting HCC in high-risk CHB patients and pattern of mutational combinations may exert greater impact on HCC risk prediction more accurately than point mutations and hence these predictors may support the existing surveillance strategies in proper management of the patients.

In vitro changes in secretion activity of rat ovarian fragments induced by molybdenum

The aim of this in vitro study was to examine the secretion activity (progesterone, 17beta-estradiol and insulin-like growth factor-I) of rat ovarian fragments after molybdenum (Mo) addition. Rat ovarian fragments were incubated with ammonium molybdate (NH(4))(6)Mo(7)O(24).4H(2)O at the doses 90, 170, 330 and 500 microg.ml(-1) for 24 h and compared with control group without Mo addition. Release of progesterone (P(4)), estradiol (17beta-estradiol) and insulin-like growth factor I (IGF-I) by ovarian fragments was assessed by radioimmunoassay (RIA). Data show that P(4) release by ovarian fragments was not affected by (NH(4))(6).Mo(7)O(24).4H(2)O addition at all the doses used (90-500 microg.ml(-1)). However, addition of ammonium molybdate was found to cause a significant (P<0.05) dose-dependent decrease (at the doses 90, 170 and 500 microg.ml(-1)) in release of 17beta-estradiol by ovarian fragments in comparison to control. Also, addition of ammonium molybdate significantly (P<0.05) inhibited IGF-I release at all the doses (90-500 microg.ml(-1)) used in the study. Results suggest ammonium molybdate induced inhibition in the release of growth factor IGF-I and its dose-dependent effect on secretion of steroid hormone 17beta-estradiol but not progesterone. These data contribute to new insights regarding the mechanism of action of Mo on rat ovarian functions.

Distinct distribution pattern of hepatitis B virus genotype C and D in liver tissue and serum of dual genotype infected liver cirrhosis and hepatocellular carcinoma patients

Aims

The impact of co-infection of several hepatitis B virus (HBV) genotypes on the clinical outcome remains controversial. This study has for the first time investigated the distribution of HBV genotypes in the serum and in the intrahepatic tissue of liver cirrhotic (LC) and hepatocellular carcinoma (HCC) patients from India. In addition, the genotype-genotype interplay and plausible mechanism of development of HCC has also been explored.

Methods

The assessment of HBV genotypes was performed by nested PCR using either surface or HBx specific primers from both the circulating virus in the serum and replicative virus that includes covalently closed circular DNA (cccDNA) and relaxed circular DNA (rcDNA) of HBV from the intrahepatic tissue. The integrated virus within the host chromosome was genotyped by Alu-PCR method. Each PCR products were cloned and sequences of five randomly selected clones were subsequently analysed.

Results

HBV/genotype D was detected in the serum of all LC and HCC patients whereas the sequences of the replicative HBV DNA (cccDNA and rcDNA) from the intrahepatic tissue of the same patients revealed the presence of both HBV/genotype C and D. The sequences of the integrated viruses exhibited the solo presence of HBV/genotype C in the majority of LC and HCC tissues while both HBV/genotype C and D clones were found in few patients in which HBV/genotype C was predominated. Moreover, compared to HBV/genotype D, genotype C had higher propensity to generate double strand breaks, ER stress and reactive oxygen species and it had also showed higher cellular homologous-recombination efficiency that engendered more chromosomal rearrangements, which ultimately led to development of HCC.

Conclusions

Our study highlights the necessity of routine analysis of HBV genotype from the liver tissue of each chronic HBV infected patient in clinical practice to understand the disease prognosis and also to select therapeutic strategy.

Abstract LB-71: Carcinogenic significance of integrated hepatitis b viral factors and its genotype in hepatocarcinogenesis

Integration of Hepatitis B Virus (HBV) is one of the major causes underlying Hepatocellular carcinoma (HCC) development. Recent studies revealed that altered expression of multiple cellular genes due to multiple random integration of viral factors lead to development of HCC. The present study aims to identify the carcinogenic significance of integrated HBV genome and its genotype in HCC development.

Host-Viral Junctions were determined in HCC (T) /adjacent tissues (NT) and cirrhotic (-HCC) tissues by sequencing of Alu PCR product followed by sequence blast. Host gene expression was checked by real time PCR. Competition between two coexisting genotypes was studied by replication assay using genotype specific PCR from media and viral core particle isolated from genotype specific plasmid transfected HepG2 cell line. Similarly, each viral genotype mediated DNA damage (γH2aX foci by confocal microscopy), ROS generation (DCFDA quantitation by Facs analysis and ER stress marker GRP78 luciferase assay), homologous recombination efficiency were also compared.

HBV integration was observed in 66.7% of T (8/12), 33.3% (4/12) NT and 75% (6/8) cirrhotic tissue samples in 18, 4 and 8 different locations respectively. These viral integration analysis within or close to several host genes, such as genes involved in differentiation, signaling, stress response, cell cycle, telomere regulations (8/30, 26.7%) etc and most of them showed altered expression. Interestingly, C-terminal truncated HBX which lost its growth suppressive domain were observed more in T (5/8, 62.5%) than NT (2/4, 50%) tissue samples. Most importantly, upon genotype analysis of each five clones in serum and tissue showed genotype C preferentially integrated in coexistence of both C and D genotype as “free virus” in tissue but D genotype observed in circulation. Genotype specific PCR from HBV/C & D cotransfected media showed that in presence of HBV/C, D replicates better than C but HBV/C with high recombination frequency generates more DNA damage and facilitate viral integration.

Thus random integration of HBV in host chromosome causes alterations in oncogenic gene expression and these alterations presumably lead to clonal selection of hepatocyte that acquires a growth advantage and proceeds towards HCC. Genotype of HBV is an important determining factor for HBV integration and liver inury.

Citation Format: Soma Banerjee, Somenath Datta, Shrabasti Roychoudhury, Debanjali Dasgupta, Amit Ghosh, Gaurav Roy, Simanti Datta, Abhijit Chowdhury. Carcinogenic significance of integrated hepatitis b viral factors and its genotype in hepatocarcinogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-71. doi:10.1158/1538-7445.AM2013-LB-71

miR-125b promotes cell death by targeting spindle assembly checkpoint gene MAD1 and modulating mitotic progression

The spindle assembly checkpoint (SAC) is a 'wait-anaphase' mechanism that has evolved in eukaryotic cells in response to the stochastic nature of chromosome-spindle attachments. In the recent past, different aspects of the SAC regulation have been described. However, the role of microRNAs in the SAC is vaguely understood. We report here that Mad1, a core SAC protein, is repressed by human miR-125b. Mad1 serves as an adaptor protein for Mad2 - which functions to inhibit anaphase entry till the chromosomal defects in metaphase are corrected. We show that exogenous expression of miR-125b, through downregulation of Mad1, delays cells at metaphase. As a result of this delay, cells proceed towards apoptotic death, which follows from elevated chromosomal abnormalities upon ectopic expression of miR-125b. Moreover, expressions of Mad1 and miR-125b are inversely correlated in a variety of cancer cell lines, as well as in primary head and neck tumour tissues. We conclude that increased expression of miR-125b inhibits cell proliferation by suppressing Mad1 and activating the SAC transiently. We hypothesize an optimum Mad1 level and thus, a properly scheduled SAC is maintained partly by miR-125b.

MYC gene amplification reveals clinical association with head and neck squamous cell carcinoma in Indian patients

BACKGROUND

Amplification of the MYC gene is reported to be associated with the development of head and neck squamous cell carcinoma (HNSCC). This study is focused to analyze the correlation between MYC gene amplification and various clinicopathological features and outcome in a cohort of 49 dysplastic and 187 primary head and neck lesions.

METHODS

MYC gene amplification was assessed by differential polymerase chain reaction using primer sets from the MYC gene as target locus and DRD2 gene as the control locus.

RESULT

The MYC gene amplification was detected in a total of 23.7% (56/236) head and neck lesions comprising 14.2% (7/49) dysplastic lesions and 26% (49/187) HNSCC samples. The clinicopathological association study between MYC gene amplification with the different clinical parameters like sex, tumor stage, tumor differentiation, lymph node status, tobacco habit and HPV 16/18 status determined significant association of MYC amplification with tumor progression (P = 0.009). Kaplan Meier analysis revealed MYC gene has no prognostic significance on survival in HNSCC.

CONCLUSION

In conclusion, our results suggest that MYC gene amplification is associated with tumor progression in HNSCC.

Transbronchial decompression of emphysematous bullae: a new therapeutic approach

Bullae are common accompaniments of chronic obstructive pulmonary disease especially emphysema. They contribute to increased lung volume and worsen the mechanical disadvantage of the inspiratory muscles by increasing the residual volume (RV) and RV/total lung capacity ratio. Thus effective decompression of a large bulla or bullae is thus important to improve the lung function of affected patients and also to provide symptomatic relief. Surgery and thoracoscopy are two commonly performed procedures used to treat bullae. Although bronchoscopic lung volume reduction has been successfully accomplished for emphysema, isolated decompression of bullae bronchoscopically has not been tried to date. A large emphysematous bulla in the left lower lobe of a surgically unfit patient was bronchoscopically punctured with a transbronchial aspiration needle; the position of the needle inside the bulla was confirmed and the air from the bulla was aspirated slowly to allow collapse. Finally, some autologous blood was instilled into the bulla before the needle was withdrawn. The patient had immediate and sustained symptomatic relief with significant improvement in lung function. Bronchoscopic transbronchial decompression of emphysematous bullae can be an effective therapeutic option and warrants further investigation.