Extracellular vesicles released during hypoxia transport heparanase and enhance macrophage migration, endothelial tube formation and cancer cell stemness

Heparanase is upregulated during the progression of most cancers and via its enzyme activity promotes extracellular matrix degradation, angiogenesis and cell migration. Heparanase expression is often associated with enhanced tumor aggressiveness and chemoresistance. We previously demonstrated that increased heparanase expression in tumor cells enhances secretion and alters the composition of tumor-released exosomes. In the present study, we discovered that extracellular vesicles (EVs) secreted by human multiple myeloma cells growing in hypoxic conditions exhibited elevated levels of heparanase cargo compared to EVs from cells growing in normoxic conditions. When macrophages (RAW 264.7 monocyte/macrophage-like cells) were exposed to EVs released by tumor cells growing in either hypoxic or normoxic conditions, macrophage migration and invasion was elevated by EVs from hypoxic conditions. The elevated invasion of macrophages was blocked by a monoclonal antibody that inhibits heparanase enzyme activity. Moreover, the heparanase-bearing EVs from hypoxic cells greatly enhanced endothelial cell tube formation consistent with the known role of heparanase in promoting angiogenesis. EVs from hypoxic tumor cells when compared with EVs from normoxic cells also enhanced cancer stemness properties of both CAG and RPMI 8226 human myeloma cells. Together these data indicate that under hypoxic conditions, tumor cells secrete EVs having an elevated level of heparanase as cargo. These EVs can act on both tumor and non-tumor cells, enhancing tumor progression and tumor cell stemness that likely supports chemoresistance and relapse of tumor.

GLI1-targeting drugs induce replication stress and homologous recombination deficiency and synergize with PARP-targeted therapies in triple negative breast cancer cells

Triple negative breast cancer (TNBC), an aggressive and highly metastatic subtype of breast cancer. Glioma-associated oncogene 1 (GLI1) is a transcription factor and effector of the Hedgehog (Hh) signaling pathway, and is predictive of poor survival for TNBC patients. A nanostring DNA Damage Response (DDR) mRNA panel was used to identify GLI1-induced regulation of DDR genes. Western blots, immunohistochemistry and immunofluorescence were used to evaluate protein expression. Colony assays and mammosphere formation assays were utilized to assess survival of cancer cells. Flow cytometry analyses were employed to evaluate changes in the cell cycle profile, and DNA fiber assays were used to analyze alterations in replication dynamics in TNBC cells. The UALCAN portal and Ensemble programs were used for computational analysis of TCGA data. CompuSyn software was used to calculate combination index (CI) values to assess synergism in drug combination experiments. Inhibition of GLI1 in TNBC cells transcriptionally downregulate expression of FANCD2 and its foci formation, and causes a homologous recombination repair (HR) deficiency. As HR-deficient cancer cells are sensitive to PARP-targeted therapies, we evaluated a combination of the GLI1 inhibitor, GANT61, and a PARP inhibitor (olaparib) in TNBC cells. Combination of GANT61 and olaparib elevated DNA damage levels and these drug combinations caused synergistic lethality to TNBC cells. Aberrantly activated GLI1 regulates HR-mediated DNA repair by transcriptionally regulating FANCD2 to overcome chemotherapy-induced replication stress and DNA damage, and it contributes to resistance of TNBC cells to therapeutics.

Hedgehog/GLI1 Transcriptionally Regulates FANCD2 in Ovarian Tumor Cells: Its Inhibition Induces HR-Deficiency and Synergistic Lethality with PARP Inhibition

Ovarian cancer (OC) is one of the most lethal type of cancer in women due to a lack of effective targeted therapies and high rates of treatment resistance and disease recurrence. Recently Poly (ADP-ribose) polymerase inhibitors (PARPi) have shown promise as chemotherapeutic agents; however, their efficacy is limited to a small fraction of patients with BRCA mutations. Here we show a novel function for the Hedgehog (Hh) transcription factor Glioma associated protein 1 (GLI1) in regulation of key Fanconi anemia (FA) gene, FANCD2 in OC cells. GLI1 inhibition in HR-proficient OC cells induces HR deficiency (BRCAness), replication stress and synergistic lethality when combined with PARP inhibition. Treatment of OC cells with combination of GLI1 and PARP inhibitors shows enhanced DNA damage, synergy in cytotoxicity, and strong in vivo anticancer responses.

Heparanase-enhanced Shedding of Syndecan-1 and Its Role in Driving Disease Pathogenesis and Progression

Both heparanase and syndecan-1 are known to be present and active in disease pathobiology. An important feature of syndecan-1 related to its role in pathologies is that it can be shed from the surface of cells as an intact ectodomain composed of the extracellular core protein and attached heparan sulfate and chondroitin sulfate chains. Shed syndecan-1 remains functional and impacts cell behavior both locally and distally from its cell of origin. Shedding of syndecan-1 is initiated by a variety of stimuli and accomplished predominantly by the action of matrix metalloproteinases. The accessibility of these proteases to the core protein of syndecan-1 is enhanced, and shedding facilitated, when the heparan sulfate chains of syndecan-1 have been shortened by the enzymatic activity of heparanase. Interestingly, heparanase also enhances shedding by upregulating the expression of matrix metalloproteinases. Recent studies have revealed that heparanase-induced syndecan-1 shedding contributes to the pathogenesis and progression of cancer and viral infection, as well as other septic and non-septic inflammatory states. This review discusses the heparanase/shed syndecan-1 axis in disease pathogenesis and progression, the potential of targeting this axis therapeutically, and the possibility that this axis is widespread and of influence in many diseases.

Therapy-induced chemoexosomes: Sinister small extracellular vesicles that support tumor survival and progression

Chemotherapy involves the use of multiple cytotoxic or cytostatic drugs acting by various mechanisms to kill or arrest the growth of cancer cells. Chemotherapy remains the most utilized approach for controlling cancer. Emerging evidence indicates that cancer cells activate various pro-survival mechanisms to cope with chemotherapeutic stress. These mechanisms persist during treatment and often help orchestrate tumor regrowth and patient relapse. Exosomes due to their nature of carrying and transferring multiple biologically active components have emerged as key players in cancer pathogenesis. Recent data demonstrates that chemotherapeutic stress enhances the secretion and alters the cargo carried by exosomes. These altered exosomes, which we refer to as chemoexosomes, are capable of transferring cargo to target tumor cells that can enhance their chemoresistance, increase their metastatic behavior and in certain cases even aid in endowing tumor cells with cancer stem cell-like properties. This mini-review summarizes the recent developments in our understanding of the impact chemoexosomes have on tumor survival and progression.

Nuclear Heparanase Regulates Chromatin Remodeling, Gene Expression and PTEN Tumor Suppressor Function

Heparanase (HPSE) is an endoglycosidase that cleaves heparan sulfate and has been shown in various cancers to promote metastasis, angiogenesis, osteolysis, and chemoresistance. Although heparanase is thought to act predominantly extracellularly or within the cytoplasm, it is also present in the nucleus, where it may function in regulating gene transcription. Using myeloma cell lines, we report here that heparanase enhances chromatin accessibility and confirm a previous report that it also upregulates the acetylation of histones. Employing the Multiple Myeloma Research Foundation CoMMpass database, we demonstrate that patients expressing high levels of heparanase display elevated expression of proteins involved in chromatin remodeling and several oncogenic factors compared to patients expressing low levels of heparanase. These signatures were consistent with the known function of heparanase in driving tumor progression. Chromatin opening and downstream target genes were abrogated by inhibition of heparanase. Enhanced levels of heparanase in myeloma cells led to a dramatic increase in phosphorylation of PTEN, an event known to stabilize PTEN, leading to its inactivity and loss of tumor suppressor function. Collectively, this study demonstrates that heparanase promotes chromatin opening and transcriptional activity, some of which likely is through its impact on diminishing PTEN tumor suppressor activity.

Abstract 2380: A novel role for PACS-1 in suppression of oncogenic replication stress in cancer cells

PACS-1 is a protein involved in trafficking, especially transport of proteins like furin and Mannose-6-phosphate into the trans-golgi network. Intriguingly, our studies identified dynamic translocation of PACS-1 during cell division and its association with chromatin in tumor cells. Downregulation of PACS-1 in cancer cell lines attenuated cell growth, induced replication stress mediated DNA damage response (DDR), such as ATM/ATR-mediated checkpoint activation, and formation RPA, FANCD2 and pH2AX foci. Consistent with these observations, live-cell imaging revealed increased nuclear translocation of PACS-1 during S-phase and until the complete cell division. These results point to a novel role for PACS-1 during normal replication or in the suppression of oncogenic replication in tumor cells. However, a direct role for PACS-1 in cancer development or progression is not clear. Analysis of the cancer genome atlas (TCGA) data revealed occurrence of PACS-1 amplifications, mutations and deletions in cancers of different tissues. PACS-1 depletion leads to proteasome-mediated degradation of HDAC2 and HDAC3, compromised chromatin maturation, leads to replication stress and genomic instability. Intriguingly, stable overexpression of PACS-1 in MDA-MB-231 cells enhanced malignant behavior of tumor cells in their ability to form soft agar colonies and matrigel invasion compared to the cells that are expressing vector control. PACS-1 downregulation promotes replication stress in tumor cells suggesting that its upregulation in tumors may be important for replication stress recovery in cancer cells and for an efficient response to chemotherapy induced DNA damage. Furthermore, Prognoscan analysis indicated that PACS-1 expression levels correlates with poor survival in multiple studies, including breast, ovarian and lung cancers, suggesting a role for PACS-1 in tumorigenesis and a biomarker for poor prognosis.

Citation Format: Chinnadurai Mani, Kaushlendra Tripathi, David W. Clark, Gary Thomas, Komaraiah Palle. A novel role for PACS-1 in suppression of oncogenic replication stress in cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2380.

Heparanase in myeloma related renal dysfunction: Role in promoting nephrotoxicity and potential as a novel biomarker for early detection

e20554

Background: Our laboratory previously demonstrated that heparanase (HPSE), an enzyme that cleaves heparan sulfate, upregulates growth factors and their receptors, resulting in enhanced multiple myeloma (MM) growth, chemoresistance, and metastasis. Targeting HPSE therapeutically decreases chemoresistance and relapse. Renal dysfunction is a major problem in MM patients with nearly 50% having renal dysfunction at diagnosis of which 19% are advanced, and 8% require dialysis. There is no specific therapy for myeloma associated renal dysfunction highlighting the need to identify novel mechanisms that lead to the development of targeted therapies. This is the first study to investigate the association between HPSE activity and renal dysfunction in MM patients by utilizing high-sensitivity biomarkers. Methods: Human Kidney 2 (HK-2) cells were treated with HPSE. Necrosis and apoptosis were assessed by flow cytometry. Cell lysates were examined for expression of kidney injury biomarkers by western blotting. HK-2 clusters were co-cultured with MM-spheroids with low or high HPSE. SCID mice were injected with 3 million luciferase-positive myeloma cells with low or high level of HPSE. Kidneys were harvested after 3 weeks and processed for studies. HPSE activity and biomarkers using multiplex magnetic bead ELISA were assessed in peripheral blood from a MM patient with serum creatinine 1.2 mg/dL and a healthy control donor. Results: HPSE induced HK-2 cell necrosis and apoptosis. HPSE induced significant expression by HK-2 cells of KIM-1, NGAL and IGFBP-7. Co-culturing HK-2 organoids with MM-spheroids expressing high HPSE compromised HK-2 organoids survival over 7 days. Damage to HK-2 cells was prevented by HPSE inhibitors Roneparstat or OGT-2115. Kidney tissues from mice harboring HPSE-high myeloma tumors expressed more KIM-1 and NGAL than those harboring HPSE-low myeloma tumors. HPSE activity was 6-fold higher and kidney injury biomarkers were many fold (range 2 – 84) higher in the plasma of a MM patient than in plasma from healthy control. Conclusions: HPSE causes kidney cellular injury which can be detected early by the measurement of high sensitivity biomarkers and can be prevented by treatment with HPSE inhibitors, Roneparstat and OGT-2115. Further studies are ongoing to investigate the association between HPSE activity and renal dysfunction in a larger cohort of MM patients which have been accrued as a part of the UAB-Integrative Molecular And Genetic Epidemiology (IMAGE) Study of Myeloma.

The multifunctional protein PACS-1 is required for HDAC2- and HDAC3-dependent chromatin maturation and genomic stability

Phosphofurin acidic cluster sorting protein-1 (PACS-1) is a multifunctional membrane traffic regulator that plays important roles in organ homeostasis and disease. In this study, we elucidate a novel nuclear function for PACS-1 in maintaining chromosomal integrity. PACS-1 progressively accumulates in the nucleus during cell cycle progression, where it interacts with class I histone deacetylases 2 and 3 (HDAC2 and HDAC3) to regulate chromatin dynamics by maintaining the acetylation status of histones. PACS-1 knockdown results in the proteasome-mediated degradation of HDAC2 and HDAC3, compromised chromatin maturation, as indicated by elevated levels of histones H3K9 and H4K16 acetylation, and, consequently, increased replication stress-induced DNA damage and genomic instability.

Abstract DP-015: BIOTINYLATED ESTROGENS A NOVEL TOOL FOR EARLY DETECTION OF ADDUCT IN OVARIAN CANCER

Elevated estrogens exert their carcinogenic effects by at least three different mechanisms; they promote cell proliferation by transcriptional regulation of estrogen responsive genes, cause generation of reactive oxygen species and other free radicals, and directly react with DNA and form potentially mutagenic adducts. However, unbalanced estrogen metabolism has been linked to development of several malignant diseases including breast, endometrial and ovarian cancer and has been identified as a risk factor for these cancers. The metabolic breakdown of estogens is regulated by a series of reactions mediated by hepatic and peripheral enzymes that balances the induction and reduction of cellular stress. An imbalance in this enzymes and processes can lead to highly reactive catechol estrogen metabolites that can react with DNA, form carcinogenic DAN-adducts and lesions. Although several studies established a connection between estrogen-induced DNA damage and carcinogenesis, the underlying molecular mechanisms have been difficult to study because of the technical challenges in detecting and analyzing the variety of different DNA lesions that are formed by estrogen compounds. Moreover, detection and analysis of these adducts are important to directly monitor estrogen metabolites induced cellular responses in the cells. Towards this, we developed a novel method using biotinylated-estrogens that allows immunodetection of estrogen-induced DNA adducts by Slot-blot and single-cell molecular combing and proximity ligation assays. Using these modified estrogens we first time quantitatively detected these adducts on DNA by immune Slot-blot techniques and on DNA fibers. Furthermore, similar to other environmental carcinogens estrogens activates replication associated DNA damage responses and induces chromosomal instability. Hence, first time our studies demonstrate that biotin-labeled estrogens could be a powerful tool to detect estrogen adducts and to probe associated DNA damage responses and cellular responses.

Citation Format: Kaushlendra Tripathi, Chinnadurai Mani, David W. Clark, Komaraiah Palle. BIOTINYLATED ESTROGENS A NOVEL TOOL FOR EARLY DETECTION OF ADDUCT IN OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr DP-015.

Abstract 2817: RAD6 promotes acquired chemoresistance and a poor prognostic marker in ovarian cancer

Ovarian cancer (OC) is deadly and incurable for patients who relapse after primary cancer is treated with surgery and platinum-based chemotherapy. Unfortunately, OC has a high rate of disease recurrence (70-80%) and most recurrent tumors are chemoresistant, causing deaths of nearly 15,000 women from this disease each year in U.S.A., which highlights the need for new therapeutic strategies. Platinum drug resistance and refractory disease pose major challenges in treating this disease and are major factors contributing to the poor survival rate of OC patients. Our studies demonstrated that RAD6 (an E2 ubiquitin conjugating enzyme) signaling is stimulated upon chemotherapeutic treatment and promotes expression of DNA repair proteins including Fanconi anemia (FA) pathway. Analysis of clinical samples revealed upregulation of RAD6 in ovarian tumors compared to normal ovarian tissues and RAD6 inhibition reduces cancer cell survival. In a pilot clinical study (n=26) comparing matched OC tumors from patients before and after carboplatin chemotherapy regimen, we found that RAD6 was upregulated after treatment and correlated with both chemoresistance and poor progression-free survival. Knockdown or inhibition of catalytic activity (small-molecule inhibitor) of RAD6 attenuated carboplatin-induced monoubiquitination of target proteins such as FANCD2, PCNA and histone 2B, thereby sensitizing OC cells to carboplatin. Interestingly, inhibition of RAD6 alone in OC cells induced replication stress and reduced cell survival and proliferation by arresting cells in the G2/M phase. Moreover, RAD6 plays an important role in the activation of the trans-lesion synthesis (TLS) pathway by monoubiquitinating PCNA and in the activation of the FA DNA repair pathway. These are critical mechanisms for cells to repair DNA crosslinks induced by platinum drugs. Together with these observations, our data suggest that inhibition of RAD6 could be a viable therapeutic target for overcoming platinum resistance and disease recurrence induced by FA pathway in ovarian cancer.

Citation Format: Chinnadurai Mani, David Clark, Ranganatha Somasagara, Sebastian Spencer, Kaushlendra Tripathi, Komariah Palle. RAD6 promotes acquired chemoresistance and a poor prognostic marker in ovarian cancer [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 2817.

Abstract 4009: Biotinylated estrogens a novel tool for early detection of adduct in ovarian cancer and their carcinogenic effects in cultured human cells

In humans, endogenous estrogens such as Estrone (E1) and 17L-estradiol (E2) regulate many physiological processes including reproduction, primarily in females, and control the growth of certain responsive cells. However, unbalanced estrogen metabolism has been linked to development of several malignant diseases including breast, endometrial and ovarian cancer and has been identified as a risk factor for these cancers. Elevated estrogens exert their carcinogenic effects by at least three different mechanisms; they promote cell proliferation by transcriptional regulation of estrogen responsive genes, cause generation of reactive oxygen species and other free radicals, and directly react with DNA and form potentially mutagenic adducts. The metabolic breakdown of estogens is regulated by a series of reactions mediated by hepatic and peripheral enzymes that balances the induction and reduction of cellular stress. An imbalance in this enzymes and processes can lead to highly reactive catechol estrogen metabolites that can react with DNA, form carcinogenic DAN-adducts and lesions. Although several studies established a connection between estrogen-induced DNA damage and carcinogenesis, the underlying molecular mechanisms have been difficult to study because of the technical challenges in detecting and analyzing the variety of different DNA lesions that are formed by estrogen compounds. Moreover, detection and analysis of these adducts are important to directly monitor estrogen metabolites induced cellular responses in the cells. Towards this, we developed a novel method using biotinylated-estrogens that allows immunodetection of estrogen-induced DNA adducts by Slot-blot and single-cell molecular combing and proximity ligation assays. Using these modified estrogens we first time quantitatively detected these adducts on DNA by immune Slot-blot techniques and on DNA fibers. Furthermore, similar to other environmental carcinogens estrogens activates replication associated DNA damage responses and induces chromosomal instability. Thus, for the first time our studies demonstrate that biotin-labeled estrogens could be a powerful tool to detect estrogen adducts and to probe associated DNA damage responses and cellular responses.

Citation Format: Kaushlendra Tripathi. Biotinylated estrogens a novel tool for early detection of adduct in ovarian cancer and their carcinogenic effects in cultured human cells [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 4009.

Rad18 is required for functional interactions between FANCD2, BRCA2, and Rad51 to repair DNA topoisomerase 1-poisons induced lesions and promote fork recovery

Camptothecin (CPT) and its analogues are chemotherapeutic agents that covalently and reversibly link DNA Topoisomerase I to its nicked DNA intermediate eliciting the formation of DNA double strand breaks (DSB) during replication. The repair of these DSB involves multiple DNA damage response and repair proteins. Here we demonstrate that CPT-induced DNA damage promotes functional interactions between BRCA2, FANCD2, Rad18, and Rad51 to repair the replication-associated DSB through homologous recombination (HR). Loss of any of these proteins leads to equal disruption of HR repair, causes chromosomal aberrations and sensitizes cells to CPT. Rad18 appears to function upstream in this repair pathway as its downregulation prevents activation of FANCD2, diminishes BRCA2 and Rad51 protein levels, formation of nuclear foci of all three proteins and recovery of stalled or collapsed replication forks in response to CPT. Taken together this work further elucidates the complex interplay of DNA repair proteins in the repair of replication-associated DSB.

RAD6 promotes DNA repair and stem cell signaling in ovarian cancer and is a promising therapeutic target to prevent and treat acquired chemoresistance

Ovarian cancer (OC) is the most deadly gynecological cancer and unlike most other neoplasms, survival rates for OC have not significantly improved in recent decades. We show that RAD6, an ubiquitin-conjugating enzyme, is significantly overexpressed in ovarian tumors and its expression increases in response to carboplatin chemotherapy. RAD6 expression correlated strongly with acquired chemoresistance and malignant behavior of OC cells, expression of stem cell genes and poor prognosis of OC patients, suggesting an important role for RAD6 in ovarian tumor progression. Upregulated RAD6 enhances DNA damage tolerance and repair efficiency of OC cells and promotes their survival. Increased RAD6 levels cause histone 2B ubiquitination-mediated epigenetic changes that stimulate transcription of stem cell genes, including ALDH1A1 and SOX2, leading to a cancer stem cell phenotype, which is implicated in disease recurrence and metastasis. Downregulation of RAD6 or its inhibition using a small molecule inhibitor attenuated DNA repair signaling and expression of cancer stem cells markers and sensitized chemoresistant OC cells to carboplatin. Together, these results suggest that RAD6 could be a therapeutic target to prevent and treat acquired chemoresistance and disease recurrence in OC and enhance the efficacy of standard chemotherapy.

FANCJ protein is important for the stability of FANCD2/FANCI proteins and protects them from proteasome and caspase-3 dependent degradation

Fanconi anemia (FA) is a rare genome instability syndrome with progressive bone marrow failure and cancer susceptibility. FANCJ is one of 17 genes mutated in FA-patients, comprises a DNA helicase that is vital for properly maintaining genomic stability and is known to function in the FA-BRCA DNA repair pathway. While exact role(s) of FANCJ in this repair process is yet to be determined, it is known to interact with primary effector FANCD2. However, FANCJ is not required for FANCD2 activation but is important for its ability to fully respond to DNA damage. In this report, we determined that transient depletion of FANCJ adversely affects stability of FANCD2 and its co-regulator FANCI in multiple cell lines. Loss of FANCJ does not significantly alter cell cycle progression or FANCD2 transcription. However, in the absence of FANCJ, the majority of FANCD2 is degraded by both the proteasome and Caspase-3 dependent mechanism. FANCJ is capable of complexing with and stabilizing FANCD2 even in the absence of a functional helicase domain. Furthermore, our data demonstrate that FANCJ is important for FANCD2 stability and proper activation of DNA damage responses to replication blocks induced by hydroxyurea.

Abstract 3734: Preclinical evaluation of Rad6 inhibition to overcome platinum resistance in ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological cancer in women in the United States. Advances in surgery and chemotherapy have not significantly changed the overall survival rate of OC for the last few decades, which highlights the need for new therapeutic strategies. Platinum drug resistance and refractory disease pose major challenges in treating this disease and are major factors contributing to the poor survival rate of OC patients. Although most patients initially respond to platinum based chemotherapy, about 80% of cases present with recurrent disease, develop platinum resistance, and die with the advanced disease. Considering the heterogeneity, small fractions of the cells could be inherently resistant to chemotherapy and/or dormant and exhibit stem-like cell properties, contributing to the resistant phenotype and disease recurrence. Although the Cancer stem cell (CSC) theory of therapeutic resistance proposes that the proportion of CSCs correlate to enhanced chemoresistance and early disease recurrence, the specific molecular mechanisms that regulate tumor cell behavior (stemness) and integrate signaling networks with aberrant oncogenic signaling in OC cells are not known. Our analysis of clinical samples revealed upregulation of Rad6, an E2 ubiquitin conjugating enzyme, in more than 80% of ovarian tumors compared to normal ovarian tissues. Upregulation of Rad6 also correlated well with tumor progression. Further analysis of molecular pathways in OC cells revealed a strong correlation between Rad6 upregulation and increased β-catenin and hedgehog signaling, stem cell like characteristics and platinum resistance. Downregulation of Rad6 using siRNAs or inhibition of its catalytic activity by a small molecule inhibitor, attenuated carboplatin induced monoubiquitination of its target proteins such as histone 2B, PCNA and proteins of the Fanconi anemia pathway thereby sensitizing OC cells to carboplatin. Interestingly, inhibition of Rad6 alone in OC cells induced replication stress and reduced cell survival and proliferation by arresting cells in the G2/M phase. Moreover, inhibition of Rad6 in various OC cell lines reduced expression of β-catenin, Gli1 and several OC stem cell markers. Moreover, Rad6 plays an important role in the activation of the trans-lesion synthesis (TLS) pathway by monoubiquitinating PCNA and in the activation of the Fanconi Anemia (FA) DNA repair pathway. These are critical mechanisms for cells to repair DNA crosslinks induced by platinum drugs. Together with these observations, our data suggest that inhibition of Rad6 could be a viable therapeutic target for overcoming platinum resistance and disease recurrence in ovarian cancer.

Citation Format: Sebastian M. Spencer, Ranganatha R. Somasagara, Kaushlendra Tripathi, David W. Clark, Hend Kothayer, Andrew D. Westwell, Rodney P. Rocconi, Komaraiah Palle. Preclinical evaluation of Rad6 inhibition to overcome platinum resistance in ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3734.

Anti oxidant potential of Metformin and Pioglitazone in Type 2 Diabetes Mellitus: Beyond their anti glycemic effect

OBJECTIVE

Insulin sensitizers might influence oxidative stress to improve insulin resistance in diabetes mellitus. The present study was designed with the aim to study the effect of Metformin & Pioglitazone on markers of oxidative stress after 4 weeks of therapy in patients with type 2 diabetes mellitus (Type 2 DM).

RESEARCH DESIGN AND METHODS

This was a prospective study with follow up of 4 weeks in patients with Type 2 DM. They were randomized into metformin treated group (N=20) and Pioglitazone treated group (N=20) and healthy age-matched control group (N=20). Data was presented as mean±S.D. Student "t" test, ANOVA and Pearson correlation co-efficient tests were performed to analyze the parametric data in this study.

RESULTS

Baseline clinical characteristics of the two study groups were similar. There is a significant difference for Fasting plasma glucose (FPG) and 2h-Post Prandial Plasma Glucose (PPPG) after 30 days of metformin and pioglitazone treatment. Metformin significantly reduced MDA (p=0.041) and increased SOD (p<0.001). Pioglitazone significantly reduced MDA (p<0.001) but failed to raise SOD level (p=0.132). Mean MDA was 4.57±0.57μM/L in metformin and 2.91±0.66μM/L in pioglitazone treatment with a p-value of <0.001. Further, a similar significant difference was obtained for SOD value by metformin and pioglitazone treatment (7.87±0.72U/ml vs. 6.94±0.53U/ml; p<0.001).

CONCLUSION

Pioglitazone was superior to Metformin to improve oxidative stress as reflected by reduction in MDA but the antioxidant effect i.e. increase in SOD was seen with metformin only. The differing mechanism of actions of the two drugs on oxidative stress favors co prescription of these drugs for better outcome in improving insulin resistance and diabetic complications.

Synthesis and in vitro anticancer evaluation of some 4,6-diamino-1,3,5-triazine-2-carbohydrazides as Rad6 ubiquitin conjugating enzyme inhibitors

Series of 4-amino-6-(arylamino)-1,3,5-triazine-2-carbohydrazides (3a-e) and N'-phenyl-4,6-bis(arylamino)-1,3,5-triazine-2-carbohydrazides (6a-e), for ease of readership, we will abbreviate our compound names as 'new triazines', have been synthesized, based on the previously reported Rad6B-inhibitory diamino-triazinylmethyl benzoate anticancer agents TZ9 and 4-amino-N'-phenyl-6-(arylamino)-1,3,5-triazine-2-carbohydrazides. Synthesis of the target compounds was readily accomplished in two steps from either bis-aryl/aryl biguanides via reaction of phenylhydrazine or hydrazinehydrate with key 4-amino-6-bis(arylamino)/(arylamino)-1,3,5-triazine-2-carboxylate intermediates. These new triazine derivatives were evaluated for their abilities to inhibit Rad6B ubiquitin conjugation and in vitro anticancer activity against several human cancer cell lines: ovarian (OV90 and A2780), lung (H1299 and A549), breast (MCF-7 and MDA-MB231) and colon (HT29) cancer cells by MTS assays. All the 10 new triazines exhibited superior Rad6B inhibitory activities in comparison to selective Rad6 inhibitor TZ9 that was reported previously. Similarly, new triazines also showed better IC50 values in survival assays of various tumor cell lines. Particularly, new triazines 6a-c, exhibited lower IC50 (3.3-22 μM) values compared to TZ9.

Allyl isothiocyanate induces replication-associated DNA damage response in NSCLC cells and sensitizes to ionizing radiation

Allyl isothiocyanate (AITC), a constituent of many cruciferous vegetables exhibits significant anticancer activities in many cancer models. Our studies provide novel insights into AITC-induced anticancer mechanisms in human A549 and H1299 non-small cell lung cancer (NSCLC) cells. AITC exposure induced replication stress in NSCLC cells as evidenced by γH2AX and FANCD2 foci, ATM/ATR-mediated checkpoint responses and S and G2/M cell cycle arrest. Furthermore, AITC-induced FANCD2 foci displayed co-localization with BrdU foci, indicating stalled or collapsed replication forks in these cells. Although PITC (phenyl isothiocyanate) exhibited concentration-dependent cytotoxic effects, treatment was less effective compared to AITC. Previously, agents that induce cell cycle arrest in S and G2/M phases were shown to sensitize tumor cells to radiation. Similar to these observations, combination therapy involving AITC followed by radiation treatment exhibited increased DDR and cell killing in NSCLC cells compared to single agent treatment. Combination index (CI) analysis revealed synergistic effects at multiple doses of AITC and radiation, resulting in CI values of less than 0.7 at Fa of 0.5 (50% reduction in survival). Collectively, these studies identify an important anticancer mechanism displayed by AITC, and suggest that the combination of AITC and radiation could be an effective therapy for NSCLC.

Rad6 upregulation promotes stem cell-like characteristics and platinum resistance in ovarian cancer

Ovarian cancer is the fifth most deadly cancer in women in the United States and despite advances in surgical and chemotherapeutic treatments survival rates have not significantly improved in decades. The poor prognosis for ovarian cancer patients is largely due to the extremely high (80%) recurrence rate of ovarian cancer and because the recurrent tumors are often resistant to the widely utilized platinum-based chemotherapeutic drugs. In this study, expression of Rad6, an E2 ubiquitin-conjugating enzyme, was found to strongly correlate with ovarian cancer progression. Furthermore, in ovarian cancer cells Rad6 was found to stabilize β-catenin promoting stem cell-related characteristics, including expression of stem cell markers and anchorage-independent growth. Cancer stem cells can promote chemoresistance, tumor recurrence and metastasis, all of which are limiting factors in treating ovarian cancer. Thus it is significant that Rad6 overexpression led to increased resistance to the chemotherapeutic drug carboplatin and correlated with tumor cell invasion. These findings show the importance of Rad6 in ovarian cancer and emphasize the need for further studies of Rad6 as a potential target for the treatment of ovarian cancer.

Abstract 3631: A novel combination of Hedgehog inhibitors with carboplatin exhibits synergy in ovarian cancer treatment by altered regulation of DNA repair networks

Ovarian cancer (OVCA) is the deadliest of all the reproductive cancers, affecting over 22,000 lives of women annually in the USA alone. In spite of their initial promising response rates to platinum drugs, more than 70% of patients relapse and die with the advanced disease. An important factor contributing to the poor outcomes in OVCA is platinum resistance (PR) and disease recurrence. Therefore, it is vital to understand the molecular mechanisms contributing to tumor resistance to platinum drugs and disease recurrence. Our preliminary studies identified aberrant activation of Hedgehog (Hh) signaling in advanced stage tumors and in OVCA cells, particularly those that are resistant to platinum agents. Further genetic and biochemical studies revealed altered expression of several cell cycle checkpoint and DNA repair genes involved in repair of platinum drug-induced DNA damage in these tumors and cell lines. Aberrant Hh signaling is implicated in the regulation of several signaling pathways including cell cycle, differentiation and DNA repair networks. Hence, we hypothesized that inhibition of Hh signaling could affect the expression of altered DNA damage response and repair networks and sensitize OVCA cells to platinum therapy. To this end, we evaluated two small molecule inhibitors of Hh signaling that target SMO (BMS-833923) and GLI transcription factors (GANT61) either alone or in combination with carboplatin in several OVCA cell lines by clonogenic and MTS cell survival assays. The therapeutic efficacy was assessed by calculating combination index (CI) values using CalcuSyn software. Simultaneously, we have also assessed the status of Hh signaling and several DNA damage response and repair networks that respond to platinum drugs. Interestingly, both the inhibitors of Hh signaling attenuated OVCA cells’ growth and their ability to form colonies. Consistent with this, inhibition of Hh signaling alone induced replication stress associated DNA damage responses (as evidenced by γH2AX foci) and compromised ATR-mediated cell cycle checkpoint responses. Similarly, combination treatment of Hh inhibitor (either SMO inhibitor or GLI inhibitor) with carboplatin potentiated the DNA damage induced by carboplatin and its cytotoxic effects in several ovarian cancer cell lines. Additionally, evaluation of combination treatments efficacies was confirmed in isogenic platinum sensitive (A2780) and resistant (A2780/CP70) OVCA cell lines. Moreover, analysis of combination therapeutic indexes revealed synergistic effects by demonstrating the CI values in the range of 0.3 to 0.49 (synergy defined as CI &lt;1) at multiple dosage combinations. Collectively, our studies suggest the combination of Hh signaling inhibitors with carboplatin could be an effective therapeutic modality in synergistic killing of ovarian cancer cells and overcoming platinum resistance.

Citation Format: Sebastian M. Spencer, Kaushlendra Tripathi, Erhong Meng, Jennifer Scalici, Rodney P. Rocconi, Komaraiah Palle. A novel combination of Hedgehog inhibitors with carboplatin exhibits synergy in ovarian cancer treatment by altered regulation of DNA repair networks. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3631. doi:10.1158/1538-7445.AM2015-3631

Abstract P5-06-07: A novel role for breast cancer associated protein 2 (BCA2) in regulation replication-stress mediated DNA damage responses

Breast cancer associated gene 2 (BCA2) has been originally identified from invasive breast cancer cells and shown to be overexpressed in over 50% of invasive breast cancers. Its expression is known to be highly associated with estrogen receptor-alpha (ER-α) status and promote cell proliferation and invasive properties. Importantly, expression of BCA2 is minimal or undetectable in most normal cells and tissues, which makes it as a valuable biomarker for ER-α positive breast cancers and a potential therapeutic target. BCA2 protein is a RING and ZINC-finger domain containing E3 ubiquitin ligase that has been shown to auto-ubiquitylate and interact with several proteins including Rab7, tetherin, ubiquitin, Ubc9 and p21, which are involved in different cellular processes. However, most of these studies have been focused on tumor progression, migration and invasive properties and almost no information on its role in carcinogenesis. Since many RING and ZINC-finger domain containing ubiquitin ligases are implicated in oncogenic signaling and DNA damage responses (DDR), in this study we examined the role of BCA2 in regulation of spontaneous and chemotherapeutics induced DDR in different breast cancer cell lines (ER-α positive versus triple negative). Interestingly, siRNA mediated down regulation of BCA2 induced spontaneous DDR, such as activation of replication checkpoint, slow cell cycle progression and double strand breaks (γH2AX foci). Exposure of BCA2 knockdown cells to DNA topoisomerase inhibitors (camptothecin and etoposide) potentiated DDR induced by these drugs. However, the molecular basis for this enhanced DDR is yet to be determined. Consistent with the previous studies, BCA2 knockdown attenuated cell proliferation, and compromised migration and invasion properties of these cells. Moreover, this novel role for BCA2 in DDR strongly suggests its status may also influence tumor response to chemo and radiation therapies and in carcinogenesis process. Further evaluation of breast cancer cell’s responses to different chemotherapeutic agents revealed distinct cellular responses based on the status of BCA2 and ER-α status. Taken together, our studies implicate a novel role for BCA2 in regulation of DDR and its influence on tumor response to chemotherapy. Additionally, we aim to present E3 ligase dependent and independent roles of BCA2 in these processes and tumor responses to different therapeutic agents.

Acknowledgment: This is work is supported by Abraham Mitchell Cancer Research Scholar Endowment grant.

Citation Format: Yuan-Hao Lee, Kaushlendra Tripathi, David Clark, Komaraiah Palle. A novel role for breast cancer associated protein 2 (BCA2) in regulation replication-stress mediated DNA damage responses [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-06-07.

Cutaneous T-cell lymphomas and their management strategies

Cutaneous T-cell lymphomas (CTCLs) comprise a heterogeneous group of lymphoproliferative disorders characterized by the proliferation of skin-homing post-thymic T-cells. It is the second most common extranodal non-Hodgekin's lymphoma. Many variants of mycosis fungoides and CTCLs are known to date, differing in clinical, histological, and immunophenotypic characteristics. Oral involvement has also been reported rarely in CTCLs. Treatment depends on the disease stage or the type of variant. New insights into the disease and the number of emerging novel therapeutic options have made it an interesting area for dermatologists and medical oncologists.

Abstract 2405: Rad18 regulates epistatic relationship between FA-BRCA and homologous recombination pathways to repair camptothecin induced DSB

DNA topoisomerase 1 (Top1) inhibiting anticancer agents such as camptothecin (CPT) show broad spectrum antitumor activity. The therapeutic activities of CPT and its analogues are attributed to prolonged stabilization of Top1-DNA covalent complexes and converting them into replication mediated double strand breaks (DSB). In spite of their therapeutic success, acquired tumor resistance poses major challenges for their therapeutic efficacy. Combination therapies using DNA repair inhibitors can increase the cytotoxic effects of these drugs and aid in overcoming such problems. Homologous recombination (HR) is the predominant DNA repair pathway involved in the repair of CPT induced DSB. Therefore, inhibition of either HR or tumors that are defective in HR could be effectively killed by Top1 inhibitors. In the same way, cells deficient in HR (ex. Rad51) or its associated proteins (such as Rad18, Fanconi anemia (FA) and breast cancer associated (BRCA1, BRCA2) proteins) are known to exhibit hypersensitivity to CPT. Specifically, FA proteins are known to associate with replication forks and implicated in repair of fork stalling lesions by HR in association with BRCA proteins. Thus, an epistatic relationship between FA and BRCA pathway has been suggested in repair of fork stalling lesions, but molecular basis for this cross-talk is not known. We previously shown that Rad18 regulates FANCD2 monoubiquitination (a key step in FA pathway) to promote HR mediated repair of CPT-induced DSB and cell survival. To further characterize the molecular interactions between Rad18 and FA-BRCA pathway in regulating HR, we have assessed their role in HR by DR-GFP reporter assays by downregulating Rad18 and FANCD2 proteins by siRNAs either alone or in combination. Consistent with survival data, cells deficient in Rad18 or FANCD2 exhibited reduced level of HR. Likewise, cells deficient in both the genes also exhibited similar results of single gene deficient cells, suggesting these two proteins work in a common pathway that promotes HR. Further biochemical and biophysical studies in Rad18 and FANCD2 deficient cells revealed dramatic decrease in nuclear localization of Rad51 and its CPT induced foci formation. Since, FANCD2 is required for BRCA2 recruitment to the sites of DSB, and BRCA2 known to associate with Rad51 and stabilize it on single stranded DNA, we further analyzed BRCA2 foci formation and its colocalization with Rad51 in response to CPT. Interestingly, our studies revealed reduced BRCA2 and Rad51 foci and their colocalization in response to CPT in Rad18 and FANCD2 deficient cells. Consistent with their role in HR, cells deficient in either of these genes exhibited chromosomal aberrations, implicating their role in accurate repair of replication coupled DSB. Together these data support that Rad18 regulates epistatic relationship between FA-BRCA and HR pathways in response to replication coupled DSB induced by CPT.

Citation Format: Kaushlendra Tripathi, Chinnadurai Mani, David Clark, Reagan Barnett, Komaraiah Palle. Rad18 regulates epistatic relationship between FA-BRCA and homologous recombination pathways to repair camptothecin induced DSB. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2405. doi:10.1158/1538-7445.AM2014-2405

Gli1 protein regulates the S-phase checkpoint in tumor cells via Bid protein, and its inhibition sensitizes to DNA topoisomerase 1 inhibitors

Aberrant expression of hedgehog molecules, particularly Gli1, is common in cancers of many tissues and is responsible for their aggressive behavior and chemoresistance. Here we demonstrate a novel and tumor-specific role for aberrant Gli1 in the regulation of the S-phase checkpoint that suppresses replication stress and resistance to chemotherapy. Inhibition of Gli1 in tumor cells induced replication stress-mediated DNA damage response, attenuated their clonogenic potential, abrogated camptothecin (CPT)-induced Chk1 phosphorylation, and potentiated its cytotoxicity. However, in normal fibroblasts, Gli1 siRNAs showed no significant changes in CPT-induced Chk1 phosphorylation. Further analysis of ataxia telangiectasia and Rad3-related protein (ATR)/Chk1 signaling cascade genes in tumor cells revealed an unexpected mechanism whereby Gli1 regulates ATR-mediated Chk1 phosphorylation by transcriptional regulation of the BH3-only protein Bid. Consistent with its role in DNA damage response, Bid down-regulation in tumor cells abolished CPT-induced Chk1 phosphorylation and sensitized them to CPT. Correspondingly, Gli1 inhibition affected the expression of Bid and the association of replication protein A (RPA) with the ATR- interacting protein (ATRIP)-ATR complex, and this compromised the S-phase checkpoint. Conversely, complementation of Bid in Gli1-deficient cells restored CPT-induced Chk1 phosphorylation. An in silico analysis of the Bid promoter identified a putative Gli1 binding site, and further studies using luciferase reporter assays confirmed Gli1-dependent promoter activity. Collectively, our studies established a novel connection between aberrant Gli1 and Bid in the survival of tumor cells and their response to chemotherapy, at least in part, by regulating the S-phase checkpoint. Importantly, our data suggest a novel drug combination of Gli1 and Top1 inhibitors as an effective therapeutic strategy in treating tumors that expresses Gli1.

ALDH1A1 maintains ovarian cancer stem cell-like properties by altered regulation of cell cycle checkpoint and DNA repair network signaling

Objective

Aldehyde dehydrogenase (ALDH) expressing cells have been characterized as possessing stem cell-like properties. We evaluated ALDH+ ovarian cancer stem cell-like properties and their role in platinum resistance.

Methods

Isogenic ovarian cancer cell lines for platinum sensitivity (A2780) and platinum resistant (A2780/CP70) as well as ascites from ovarian cancer patients were analyzed for ALDH+ by flow cytometry to determine its association to platinum resistance, recurrence and survival. A stable shRNA knockdown model for ALDH1A1 was utilized to determine its effect on cancer stem cell-like properties, cell cycle checkpoints, and DNA repair mediators.

Results

ALDH status directly correlated to platinum resistance in primary ovarian cancer samples obtained from ascites. Patients with ALDH^HIGH displayed significantly lower progression free survival than the patients with ALDH^LOW cells (9 vs. 3 months, respectively p<0.01). ALDH1A1-knockdown significantly attenuated clonogenic potential, PARP-1 protein levels, and reversed inherent platinum resistance. ALDH1A1-knockdown resulted in dramatic decrease of KLF4 and p21 protein levels thereby leading to S and G2 phase accumulation of cells. Increases in S and G2 cells demonstrated increased expression of replication stress associated Fanconi Anemia DNA repair proteins (FANCD2, FANCJ) and replication checkpoint (pS317 Chk1) were affected. ALDH1A1-knockdown induced DNA damage, evidenced by robust induction of γ-H2AX and BAX mediated apoptosis, with significant increases in BRCA1 expression, suggesting ALDH1A1-dependent regulation of cell cycle checkpoints and DNA repair networks in ovarian cancer stem-like cells.

Conclusion

This data suggests that ovarian cancer cells expressing ALDH1A1 may maintain platinum resistance by altered regulation of cell cycle checkpoint and DNA repair network signaling.

Study of Mutations in β-Thalassemia Trait among Blood Donors in Eastern Uttar Pradesh

BACKGROUND

Knowledge on distribution of different mutations of thalassaemia, which are prevalent in a particular area, is a prerequisite for prenatal diagnosis.

OBJECTIVES

Studying mutations in β - thalassaemia trait among blood donors in eastern Uttar Pradesh, India.

MATERIAL AND METHODS

One thousand non - remunerated voluntary blood donors who were between 18 - 40 years of age, were included in the study. Both replacement and voluntary healthy blood donors were included. 4ml of venous blood was collected and it was stored at 4°C. Complete Blood Count (CBC), Haemoglobinopathy Screening and Molecular Analysis by ARMS - PCR (Amplification Refractory Mutation System - PCR) were done. Screening for β thalassaemia was done in a blood bank by using D - 10, Bio Rad, which was based on High Performance Liquid Chromatography (HPLC).

RESULTS

Twenty Eight subjects with β- thalassaemia trait were found among 1000 voluntary blood donors. IVS 1-5 (G-C) mutation was most common type (50%), followed by FS 8/9 (+G) 25% which was the second most common type. In our study, a rare mutation of CD 16 (-C) was also found. Out of 14 subjects who had IVS 1-5 (G-C) mutation (most common), six were from Varanasi (6/261) and five of them were Sindhis. It was seen that FS 41/42 (TCTT) mutation was distributed among all groups of populations which had higher prevalences of β-thalassaemia trait.

CONCLUSION

A comprehensive knowledge on beta thalassaemia mutations is necessary for determining a prenatal diagnosis. The occurrence of mutations may vary according to geographic region. Therefore, this study dealt with current problem of unknown mutations, in order to avoid complications.

Identification of C18:1-phytoceramide as the candidate lipid mediator for hydroxyurea resistance in yeast

Recent studies showed that deletion of ISC1, the yeast homologue of the mammalian neutral sphingomyelinase, resulted in an increased sensitivity to hydroxyurea (HU). This raised an intriguing question as to whether sphingolipids are involved in pathways initiated by HU. In this study, we show that HU treatment led to a significant increase in Isc1 activity. Analysis of sphingolipid deletion mutants and pharmacological analysis pointed to a role for ceramide in mediating HU resistance. Lipid analysis revealed that HU induced increases in phytoceramides in WT cells but not in isc1Δ cells. To probe functions of specific ceramides, we developed an approach to supplement the medium with fatty acids. Oleate (C18:1) was the only fatty acid protecting isc1Δ cells from HU toxicity in a ceramide-dependent manner. Because phytoceramide activates protein phosphatases in yeast, we evaluated the role of CDC55, the regulatory subunit of ceramide-activated protein phosphatase PP2A. Overexpression of CDC55 overcame the sensitivity to HU in isc1Δ cells. However, addition of oleate did not protect the isc1Δ,cdc55Δ double mutant from HU toxicity. These results demonstrate that HU launches a lipid pathway mediated by a specific sphingolipid, C18:1-phytoceramide, produced by Isc1, which provides protection from HU by modulating Swe1 levels through the PP2A subunit Cdc55.

Abstract 2475: Design and development of combretastatin based unsymmetrical terphenyls as small molecule antimitotic agents

The microtubule system of the eukaryotic cell plays indispensable role in the process of separating duplicated chromosomes before the cell division. Due to this essential function, they have been an important target for the development of cancer therapeutics. Several natural products such as Taxol, Vinca alkaloids, colchicine and their synthetic analogues that target microtubules have been used to treat several malignancies. However, cancer cells develop resistance to several of these agents by altering drug transporters and signaling pathways. Recently, combretastatins (CA) a group of diarylstilbenes isolated originally from stem wood of the South African tree Combretum caffrum have received much attention due to their potent anticancer activity against wide variety of human cancers including those that are multidrug resistant. These molecules specifically bind to the colchicine-binding site of the tubulins and prevent their polymerization required for the mitotic tubule formation thus possesses anti-proliferative and antivascular activities. A water soluble disodium phosphate derivative of CA has shown promising results in clinical trials of several malignancies, thus stimulating significant interest in a variety of CA analogues. However, the cis configuration of CA favors to form thermodynamically more stable trans isomer during storage and administration, producing a dramatic reduction in both tubulin binding and antiproliferative activities. Considering these limitations, we designed and synthesized a series of 3′,4′,5′-trimethoxy-2-phenylbiphenyl derivatives as cis-restricted CA analogues and evaluated for their antiproliferative activity, inhibitory effects on tubulin polymerization, cell cycle effects and apoptosis induction. Moreover, we adopted a novel strategy to synthesize these low molecular weight unsymmetrical terphenyls by a new synthetic methodology using Suzuki coupling in a one pot operation without isolating the biaryls intermediate. A majority of these compounds demonstrated significant anti-proliferative activity against most of the cell lines tested including that are multi-drug resistant. Interestingly, some of these compounds elicited DNA damage response in a dose dependent manner. Specifically, the compounds with acetamido and acetyl functional groups exhibited significant inhibitory activities in tubulin polymerization and growth inhibition. Consistent with their FACS profiles, Immunocytochemistry and biochemical analysis revealed loss of intact microtubule structure, up regulation of cyclin B1 and aurora kinase B mRNA levels, corresponding to growth arrest in the G2/M. More importantly, our one pot synthesis strategy of unsymmetrical terphenyls of this structural class paves the way for design and development of novel anticancer agents.

Citation Format: Surendra Reddy Punganuru, Sadanandam Palle, Kaushlendra Tripathi, Komaraiah Palle. Design and development of combretastatin based unsymmetrical terphenyls as small molecule antimitotic agents. [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 2475. doi:10.1158/1538-7445.AM2013-2475

Kinetic and Mechanistic Study of the Influence of Micelles on the Oxidation of Acetone by N-Bromophthalimide in Aqueous Acetic Acid Medium

The effect of cationic micelles of Cetyltrimethylammonium bromide (CTAB) and anionic micelles of Sodium dodecyl Sulphate (SDS) on the kinetics of oxidation of acetone by N-Bromophthalimide (NBP) was studied iodometrically at 308 K. In addition to kinetic experiments, conductivity measurements have also been done to obtain critical micelle concentration and other thermodynamic properties. The kinetic observations indicate fractional order and first order dependence, with respect to [Acetone] and [NBP] respectively. Cationic surfactant (CTAB) strongly catalysed the oxidation of acetone in aqueous acetic acid medium and typical kobs and [CTAB] profile was observed i.e. with the progressive increase in [CTAB], the reaction rate increased, at higher concentration constancy in kobs was observed, whereas anionic surfactant (SDS) was found to show no considerable effect on reaction rate. Mercuric acetate and phthalimide exhibited nil effect on the reaction rate. The presence of inorganic salts (KCl, KBr) exhibits positive effect in the reaction rate. The various activation parameters in presence of CTAB and SDS have been also evaluated. A suitable mechanism consistent with the experimental findings has been proposed. The binding constant with surfactants has been evaluated.

Pharmacognostical study of Tamalaki (Phyllanthus fraternus Webster), a herb used in Tamaka-svasa

Tamalaki is a herbacious medicinal plant, described in Ayurvedic texts in many occurrences with different properties, actions, uses and synonyms, supposed to indicate more than one species commonly used in practice. Modern scholars mostly suggest Phyllanthus fraternus Webster (syn. P. niruri Linn.), P. amarus Schum. and Thonn. and P. urinaria Linn. as the source plants of Tamalaki. In this study, an attempt has been made to designate P. fraternus as the source plant of Tamalaki used in the treatment of Tamaka-svasa (Bronchial asthma) and other respiratory disorders by analyzing therapeutic uses, actions, properties, taste, synonyms as well as pharmacognostical characters. Smooth capsule, six tepals, less and short fibrous root, pentagonal outline with wing-shaped young stem are some of the specific characters observed in this species.

Nicotinamide induces Fob1-dependent plasmid integration into chromosome XII in Saccharomyces cerevisiae

In the ribosomal DNA (rDNA) array of Saccharomyces cerevisiae, DNA replication is arrested by the Fob1 protein in a site-specific manner that stimulates homologous recombination. The silent information regulator Sir2, which is loaded at the replication arrest sites by Fob1, suppresses this recombination event. A plasmid containing Fob1-binding sites, when propagated in a yeast strain lacking SIR2 is integrated into the yeast chromosome in a FOB1-dependent manner. We show that addition of nicotinamide (NAM) to the culture medium can stimulate such plasmid integration in the presence of SIR2. Pulsed-field gel electrophoresis analysis showed that plasmid integration occurred into chromosome XII. NAM-induced plasmid integration was dependent on FOB1 and on the homologous recombination gene RAD52. As NAM inhibits several sirtuins, we examined plasmid integration in yeast strains containing deletions of various sirtuin genes and observed that plasmid integration occurred only in the absence of SIR2, but not in the absence of other histone deacetylases. In the absence of PNC1 that metabolizes NAM, a reduced concentration of NAM was required to induce plasmid integration in comparison with that required in wild-type cells. This study suggests that NAD metabolism and intracellular NAM concentrations are important in Fob1-mediated rDNA recombination.

Hydroxyurea treatment inhibits proliferation of Cryptococcus neoformans in mice

The fungal pathogen Cryptococcus neoformans (Cn) is a serious threat to immunocompromised individuals, especially for HIV patients who develop meningoencephalitis. For effective cryptococcal treatment, novel antifungal drugs or innovative combination therapies are needed. Recently, sphingolipids have emerged as important bioactive molecules in the regulation of microbial pathogenesis. Previously we reported that the sphingolipid pathway gene, ISC1, which is responsible for ceramide production, is a major virulence factor in Cn infection. Here we report our studies of the role of ISC1 during genotoxic stress induced by the antineoplastic hydroxyurea (HU) and methyl methanesulfonate (MMS), which affect DNA replication and genome integrity. We observed that Cn cells lacking ISC1 are highly sensitive to HU and MMS in a rich culture medium. HU affected cell division of Cn cells lacking the ISC1 gene, resulting in cell clusters. Cn ISC1, when expressed in a Saccharomyces cerevisiae (Sc) strain lacking its own ISC1 gene, restored HU resistance. In macrophage-like cells, although HU affected the proliferation of wild type (WT) Cn cells by 50% at the concentration tested, HU completely inhibited Cn isc1Δ cell proliferation. Interestingly, our preliminary data show that mice infected with WT or Cn isc1Δ cells and subsequently treated with HU had longer lifespans than untreated, infected control mice. Our work suggests that the sphingolipid pathway gene, ISC1, is a likely target for combination therapy with traditional drugs such as HU.

Pneumatocele in an adult

We report a case of 25-year-old male who presented with high grade fever with cough and expectoration. Chest examination revealed amphoric breath sounds on the right interscapular region. Chest X ray revealed multiple air fluid levels with collapse lung at places. Staph pneumonia with pneumatoceles is common in children but uncommon to in adult population.

Dibutyryl c-AMP as an inducer of sporidia formation: biochemical and antigenic changes during morphological differentiation of Karnal bunt (Tilletia indica) pathogen in axenic culture

Effect of dibutyryl adenosine 3',5'-cyclic monophosphate (dbc-AMP), an analogue of c-AMP, was investigated on growth and morphological differentiation of Tilletia indica. Exponential growth was observed up to 21 days in both presence and absence of dbc-AMP; however, increasing concentration of dbc-AMP was deleterious to mycelial growth in liquid culture. A slow increase of mycelial biomass up to 21 days and decline at 30 days in the presence of 2.5 mM dbc-AMP was observed, therefore, this concentration was chosen in subsequent investigations. The inhibitory influence of dbc-AMP was further substantiated by decrease in soluble protein. The fungus on exposure to dbc-AMP experienced morphological differentiation from vegetative mycelial phase to sporogenous mycelial phase, and was induced to produce filiform sporidia. Use of quantitative ELISA further suggested that sporidia formation took more than 21 days in the presence of dbc-AMP. Variations of proteins during different stages of T. indica grown in the presence and absence of dbc-AMP suggested the expression of stage-specific proteins or differential expression of proteins induced by dbc-AMP. The changes in expression of cell surface antigens as evidenced from decrease and increase binding of anti-mycelial and anti-sporidial antibodies in dbc-AMP treated culture by ELISA was further interpreted on the basis of morphological differentiation from mycelial to sporidial phase

Effect of pioglitazone and rosiglitazone on mediators of endothelial dysfunction, markers of angiogenesis and inflammatory cytokines in type-2 diabetes

The purpose of this study was to assess the effects of PPAR-gamma agonists (pioglitazone and rosiglitazone) on mediators of endothelial dysfunction and markers of angiogenesis in patients with type-2 diabetes. Pioglitazone group showed favorable reductions in serum total cholesterol, triglycerides, LDL cholesterol, VLDL cholesterol and increase in HDL cholesterol as compared to rosiglitazone group, after 16 weeks of treatment and also with control group. There was significant reduction of CRP level in pioglitazone and rosiglitazone group. The level of serum TNF-alpha decreased significantly in pioglitazone and mildly decreased in rosiglitazone group. The level of VEGF, IL-8 and Angiogenin were increased in pioglitazone than rosiglitazone group. There were no significant changes observed in the serum angiogenin and IL-8 levels in the control group. Pioglitazone and rosiglitazone therapy in type-2 diabetes subjects have additional benefits of reducing mediators of endothelial dysfunction. Increase in angiogenesis markers in patients receiving pioglitazone could have variable effects in diabetic nephropathy and retinopathy as there may be increased vascular neogenesis. Pioglitazone has advantage over rosiglitazone in lowering lipid and proinflammatory cytokines.

Differential dynamics of splicing factor SC35 during the cell cycle

Pre-mRNA splicing factors are enriched in nuclear domains termed interchromatin granule clusters or nuclear speckles. During mitosis, nuclear speckles are disassembled by metaphase and reassembled in telophase in structures termed mitotic interchromatin granules (MIGs). We analysed the dynamics of the splicing factor SC35 in interphase and mitotic cells. In HeLa cells expressing green fluorescent protein (GFP)-SC35, this was localized in speckles during interphase and dispersed in metaphase. In telophase, GFP-SC35 was highly enriched within telophase nuclei and also detected in MIGs. Fluorescence recovery after photobleaching (FRAP) experiments revealed that the mobility of GFP-SC35 was distinct in different mitotic compartments. Interestingly, the mobility of GFP-SC35 was 3-fold higher in the cytoplasm of metaphase cells compared with interphase speckles, the nucleoplasm or MIGs. Treatment of cells with inhibitors of cyclin-dependent kinases (cdks) caused changes in the organization of nuclear compartments such as nuclear speckles and nucleoli, with corresponding changes in the mobility of GFP-SC35 and GFP-fibrillarin. Our results suggest that the dynamics of SC35 are significantly influenced by the organization of the compartment in which it is localized during the cell cycle.

Acanthamoebae presenting as primary meningoencephalitis in AIDS

A rare case of Acanthamoebae meningoencephalitis is diagnosed in cerebrospinal fluid (CSF) of a 24 years old male suffering from acquired immunodeficiency syndrome (AIDS) patient on the basis of bright field microscopy and culture growth on non-nutrient agar with Escherichia coli. This case illustrates that Acanthamoebae should be considered in the differential diagnosis of meningoencephalitis in AIDS in addition to tuberculosis and cryptococcus infection in tropical areas.

Decreasing incidence of renal cortical necrosis in patients with acute renal failure in developing countries: a single-centre experience of 22 years from Eastern India

BACKGROUND

Renal cortical necrosis (RCN) accounts for 2% of all cases of acute renal failure (ARF) in adults and 15-20% of ARF during the third trimester of pregnancy in developed nations. However, RCN incidence is higher in developing countries ranging from 6-7% of all cases of acute renal failure. The present study describes changing trends in the clinical spectrum of RCN in patients with ARF in Eastern India.

METHODS

Patients with ARF suspected to have RCN on clinical grounds underwent percutaneous renal biopsy. Patients showing cortical necrosis on histology were included in the present study. Diffuse and patchy cortical necrosis was classified based on standard histological criteria. The patients with cortical necrosis were studied over a period of 22 years; from July 1984 to December 2005. The results of our observation were compared with respect to etiology, incidence, prognosis and outcome of renal cortical necrosis in two study periods; namely, 1984-1994 and 1995-2005.

RESULTS

The incidence of RCN was 3.12% of all cases of ARF of diverse etiology. RCN was observed in 57 patients; obstetric 32 (56.2%); non-obstetric 25 (43.8%). Diffuse cortical necrosis was the dominant lesion in 41 (71.9%) patients and the remaining 16 (28%) patients had patchy cortical necrosis. The overall incidence of RCN in obstetric ARF was 15.2%; the incidence being higher (11.9%) in the post-abortal group in comparison to 3.3% in late pregnancy. RCN had occurred complicating abruptio placentae, puerperal sepsis and postpartum haemorrhage (PPH) in late pregnancy, while septic abortion was the sole cause of RCN in early pregnancy. Haemolytic uraemic syndrome (HUS) was the major (31.5%) cause of RCN in the non-obstetric group and miscellaneous factors were responsible in seven (12.3%) patients. Partial recovery of renal function was observed in 11 (19.2%), and 16 (28%) patients had progressed to ESRD. The incidence of RCN decreased from 6.7% in 1984-1994 to 1.6% in 1995-2005 of total ARF cases. RCN following obstetrical complication decreased significantly; 4.7% in the 1990s to 0.5% of the total ARF cases, in the 2000s. The mortality decreased to 19% in 1995-2005 from the initial high mortality of 72% in 1984-1994. The renal prognosis improved as a result of the decreased mortality of patients.

CONCLUSION

We observed a decreasing trend in the incidence of RCN in patients with ARF in recent years, which is associated with increased patient survival and better renal prognosis. This improvement was mainly due to declining incidence and severity of RCN in obstetrical ARF.

Effect of glycaemic control on apoptosis in diabetic wounds

OBJECTIVE

To study the effect of glycaemic control on apoptosis in chronic ulcers in diabetic patients and the differential roles of insulin and oral hypoglycaemic agents (OHAs).

METHOD

Ten non-diabetic (group I) and 20 diabetic patients (groups II and III), with a wound of more than four weeks' duration, who were attending the wound clinic at University Hospital, Varanasi, India were recruited. The 10 patients in group 11 received insulin and the 10 in group III an oral hypoglycaemic agent; all had diabetic foot ulcers. Wound biopsy and other routine investigations were performed. Both DNA fragmentation and morphological changes under light microscopy (apoptotic index) were used as determinants of apoptosis. Different variables, including fasting and post-prandial blood sugar, serum low-density lipoprotein (LDL) and markers of microangiopathy, such as proteinuria and diabetic retinopathy, were compared with apoptosis.

RESULTS

DNA fragmentation in groups I, II and III was 40.00 +/- 2.97, 45.26 +/- 3.21 and 60.8 +/- 3.13 respectively (p < 0.01). Near linear correlation was observed with blood sugar level, particularly post-prandial blood sugar (p < 0.05) and DNA fragmentation. DNA fragmentation was significantly correlated with serum LDL and proteinuria, and it was much greater in the OHA group than in the insulin group (p < 0.05). Similarly, in the diabetic patients with background retinopathy the DNA fragmentation was 46.50 +/- 3.42 (n=3) in the insulin group and 66.70 +/- 6.48 (n=4) in the OHA group (p < 0.05).

CONCLUSION

There is a significant increase in apoptosis in diabetic wounds with poorly controlled blood sugar and microangiopathy. This increase was greater in patients on OHAs than those on insulin, and it contributes to delayed wound healing. Morphological markers do not appear to be a reliable index of apoptosis in the diabetic wound.

Primary amyloidosis presenting with predominant lymphnodal masses

A 50 year young farmer presented with clinical features of bilateral carpal tunnel syndrome and generalized lymphadenopathy including paratracheal and retroperitoneal lymphodes. The histological diagnosis confirmed primary amyloidosis of lymphnodes. Presentation of primary amyloidosis as lymphnodal mass with deposition of amyloid in carpal tunnel is extremely rare and can only be diagnosed by histochemistry. The clinical response to drugs is variable and needs surgical intervention for decompressive therapy which can improve the symptoms of carpal tunnel syndrome.

Mucocutaneous lesions in transplant recipient in a tropical country

Dermatological manifestations are common in renal transplant patients, but differ markedly with ethnic group and geographical location. We studied mucocutaneous lesions in 54 renal allograft recipients (related donors = 30; unrelated donors = 24) living in tropical atmospheres. Their gender was 50 males, and 4 females ranging in age between 15 and 63 years (mean = 37.84 years). The mean duration of follow-up was 124 months (range = 4 to 173 months). All patients received kidneys from living donors and were kept on immunosupression with mean daily doses of prednisolone, azathioprine, and cyclosporine of 10.2 mg, 68.6 mg, and 252 mg, respectively. The mean trough concentration of cyclosporine was 185 ng/mL. The mucocutaneous lesions were divided into four groups: drug-induced (n = 24, 44.4%), fungal (n = 18, 33.3%), viral (n = 9, 16.6%), and bacterial (n = 10, 18.5%). Cushingoid features, gum hypertrophy, and hypertrichosis were seen in 7 (12.9%) patients. Steroid acne was seen in three cases. Pityriasis versicolor was the most common (20.3%) fungal infection of the skin. In addition, Tinea unguium and mucocutaneous candidiasis were noted in four and three cases respectively. Herpes virus infection (Herpes zoster 5; Herpes simplex 2) was noted in 7 (12.9%) cases. Chicken pox at 5 years posttransplant and cutaneous vasculitis associated with cytomegalovirus disease at 6 months posttransplant were seen in one case each. We have not seen warts in our patients. Pyogenic bacterial infection of skin in the form of abscess (n = 6), cellulitis (n = 3), and pyoderma (n = 1) were observed in 10 (18.5%) patients. Thus, drug-induced mucocutaneous side effects and skin fungal infections are the most common dermatological manifestations among renal transplant recipients living in a tropical country.

Spectrum of renal disease in malaria

Between January 2000 and December 2001, renal involvement in 81 cases of malaria was studied. Their age ranged between 05 and 66 (mean 35.5) years. Distribution of malarial parasite was P falciparum (75), mixed infection (4) and P vivax (2). The evidence of clinical renal disease in the form of acute renal failure, electrolyte abnormality, abnormal urinary sediment and increased urinary protein excretion (>500 mg/24 hours) was found in 100%, 91.3%, 46.9% and 18.5% respectively. Probable aetiopathogenesis of acute renal failure (ARF) was multifactorial. Volume depletion (72.8%) was the dominant cause of ARF in these patients. In addition, hyperbilirubinaemia, intravascular haemolysis and sepsis were responsible for ARF in 64.2%, 70.3% and 25.9% cases respectively. All the patients were managed with anti-malarial drugs and dialysis support was needed in 35 patients (43.2%). Prognosis of malarial acute renal failure is favourable with mortality rate of 18.5%. Multi-organ failure was the commonest cause (33.3%) of death.