Abstract 1930: 4-nitroquinoline-1-oxide enhances induction of apoptosis preferentially in HPV positive head and neck squamous cell carcinoma cells

Background: Tobacco use and human papillomavirus (HPV) infection are both strong contributors to the oncogenesis of head and neck squamous cell carcinoma (HNSCC). Despite HPV's causative role in HNSCC, it confers no statistically significant difference in mutational profile between HPV-associated HNSCC smokers and non-smokers. Our earlier preliminary data suggested that HPV positive (+) HNSCC cells have better activation of DNA repair proteins compared to HPV negative (-) HNSCC cells when treated with 4NQO, a mutagen and carcinogen which serves as a surrogate for tobacco exposure. This may partially explain HPV+ HNSCC's higher mutational resistance. In addition to increased DNA repair, HPV+ cells may also eliminate mutations through higher rates of apoptosis compared to HPV- cells. Hence, we wanted to test this hypothesis by analyzing the effects of 4NQO on apoptosis in HPV+ and HPV- HNSCC cells.

Methods: NOK, NOK E6.E7, SCC40 (HPV-), SCC104 and UMSCC47 (HPV+) cells were treated with different concentrations of 4NQO (0, 0.1, and 0.2 ug/ml) for 24 and 48 hours. Untreated (control) and 4NQO treated cells were assessed for cell viability using MTT assay. Apoptotic cells were determined using Annexin-V FITC flow cytometry analysis, and Western blot was performed to check the apoptotic proteins for the afore-mentioned control and 4NQO treatments.

Results: MTT assay showed decreased cell viability of NOK E6.E7, SCC47 and SCC104 cells in response to 4NQO treatment compared to relatively higher cell viability of SCC40 cells. Flow cytometry confirmed that HPV+ HNSCC cells are relatively more apoptotic compared to HPV- cells following 4NQO treatment at 24 and 48 hours. This is further supported by activation of pro-apoptotic proteins including p53, cleaved caspase 3, cleaved PARP, cleaved caspase 9, and p21 to a greater extent in HPV+ cells at different time points of 4NQO treatment using Western blot analysis.

Conclusion: Our in-vitro data suggest HPV may stimulate a protective measure against smoking-induced mutations by increasing apoptosis before cells can contribute to the HNSCC mutational profile. Taken together, these data explain why HPV associated HNSCC have a better prognosis than HPV negative irrespective of smoking history.

Citation Format: Gauri Shishodia, Alice Lee, Rhodee Ric Toledo, Emily Zimmerman, Xiaohua Rong, Adam Xiao, Lynn Harrison, Cherie Ann Nathan. 4-nitroquinoline-1-oxide enhances induction of apoptosis preferentially in HPV positive head and neck squamous cell carcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1930.

Comparison between irradiating and autoclaving citrus wastes as substrate for solid-state fermentation by Aspergillus aculeatus

Agricultural or food processing wastes cause serious environmental burden and economic losses. Solid-state fermentation using these wastes is an attractive option to valorize these wastes. However, conventional autoclaving of substrate may degrade nutrients and generate toxins. Unsterilization of the substrate will cause undesired microbial contamination. Therefore, we compared irradiation with autoclaving to treat citrus wastes as substrate for solid-state fermentation by Aspergillus aculeatus. By comparing microbial growth, enzymes tested and medium consumption, irradiated substrate had higher biomass and extracellular protein, more sugar consumption and higher enzyme production than those with autoclaved substrate. Irradiation prevented the generation of cell-inhibiting components such as 5-hydroxymethylfurfural (5-HMF) whereas preserved the flavonoids well that are often enzyme inducers. These findings suggest that irradiation of agricultural and food processing wastes as substrate has advantages over autoclaving for solid-state fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This study proposes irradiation as an alternative to sterilize agricultural residues rich in nutrients and thermosensitive compounds, such as citrus wastes for fungal solid-state fermentation and production of enzymes.

Direct observation of the fast and robust folding of a slipknotted protein by optical tweezers

Understanding the folding mechanism of knotted and slipknotted proteins has attracted considerable interest. Due to their topological complexity, knotted and slipknotted proteins are predicted to fold slowly and involve large topological barriers. Molecular dynamics simulation studies suggest that a slipknotted conformation can serve as an important intermediate to help greatly reduce the topological difficulty during the folding of some knotted proteins. Here we use a single molecule optical tweezers technique to directly probe the folding of a small slipknotted protein AFV3-109. We found that stretching AFV3-109 can lead to the untying of the slipknot and complete unfolding of AFV3-109. Upon relaxation, AFV3-109 can readily refold back to its native slipknot conformation with high fidelity when the stretching force is lower than 6 pN. The refolding of AFV3-109 occurs in a sharp two-state like transition. Our results indicate that, different from knotted proteins, the folding of a slipknotted protein like AFV3-109 can be fast, and may not necessarily involve a high topological barrier.

Direct monitoring of equilibrium protein folding–unfolding by atomic force microscopy: pushing the limit

We report the direct observation of equilibrium folding–unfolding dynamics of a mechanically labile, three helix bundle protein GA using a commercial atomic force microscope (AFM).

Abstract 5846: The use of sodium sulfide, a hydrogen sulfide donor, to sensitize glioblastoma multiforme to photon and proton radiotherapy

Glioblastoma multiforme (GBM) is the most common glial tumor accounting for 12-15% of all brain tumors worldwide. It is a rapidly progressing, life-threatening disease with a median survival of 3-6 months when left untreated. Minimal advancements in the treatment of GBM have limited its management. Conventional treatment with surgical resection of the primary tumor followed by photon radiation (60 Gy in 2 Gy fractions) in combination with adjuvant chemotherapy can limit recurrence and prolong median survival to 15 months.

Proton radiotherapy has received increased attention in recent years due to its more precise energy deposition and 10% higher relative biological effectiveness (RBE) when compared to photon therapy. Several clinical trials have shown that high dose photon/proton therapy reduces central recurrence rate and extends median survival of GBM patients to 21.6 months. Unfortunately, the high rate of radionecrosis has limited its widespread adoption. Radiosensitization agents may overcome this problem by allowing for the use of lower radiation doses to achieve comparable cytotoxic effects; however, no radiosensitizers are currently approved for the treatment of GBM.

The current study examines the use of sodium sulfide (Na2S), a hydrogen sulfide donor, as a radiosensitizing agent for both photon and proton therapy in two human glioblastoma cell lines, T98G and U87-MG. Survival curves were generated for T98G cells using a colony forming assay. Protons had an increased RBE of 1.18, which is in close agreement to the accepted RBE of 1.1. Na2S (0 μM, 10 μM, 100 μM, 500 μM, 1000 μM) was given as a pre-treatment in two 2-hour incubations: 2 hours prior to radiation and again immediately before radiation. Na2S alone exhibited a concentration dependent cytotoxic effect with maximal killing of approximately 50% at 500 μM. Further increases in sodium sulfide up to 1000μM had no effect on cell survival. Similar killing was not observed in a non-cancer mouse retinal endothelial cell line even at extremely high doses of 1000 μM suggesting that Na2S cytotoxicity is specific and limited to cancer cells. Na2S increased killing in both photons and protons at 6 Gy by decreasing the surviving fraction from 27.7% to 20% and 16% to 3% respectively. Initial studies into the mechanism of radiosensitization using bleomycin as a radiomimetic agent have suggested Na2S increases the number of DNA double strand breaks (DSB), a highly cytotoxic form of DNA damage, as seen by γH2AX staining in both T98G and U87-MG cells.

The benefits of high dose radiation therapy, particularly with proton boost, in the treatment of high-grade central nervous system tumors such as GBM are apparent, but the increased risk of radionecrosis has limited its use. While further studies need to be conducted to elucidate the exact mechanism, preliminary results strongly suggest that sodium sulfide can act as a radiosensitizing agent by increasing DNA DSB formation.

Citation Format: Adam Xiao, Rajesh Pidikiti, Matthew Maynard, Nader Sheibani, Lynn Harrison. The use of sodium sulfide, a hydrogen sulfide donor, to sensitize glioblastoma multiforme to photon and proton radiotherapy [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 5846. doi:10.1158/1538-7445.AM2017-5846

From trash to treasure: The untapped potential of endothelial microparticles in neurovascular diseases

Discovered in 1947, microparticles (MP) represent a group of sub-micron cell-derived particles isolated by high speed centrifugation. Once regarded as cellular 'trash', in the past decade MP have gained tremendous attention in both basic sciences and medical research both as biomarkers and mediators of infection, injury and response to therapy. Because MP bear cell surface markers derived from parent cells, accumulate in extracellular fluids (plasma, serum, milk, urine, cerebrospinal fluid) MP based tests are being developed commercially as important components in 'liquid biopsy' approaches, providing valuable readouts in cardiovascular disease and cancer, as well as stroke, Alzheimer's disease and Multiple Sclerosis. Importantly, MP have been reported as mobile transport vectors in the intercellular transfer of mRNAs, microRNAs, lipids and proteins. Here we discuss MP structure, properties and functions with particular relevance to neurological and neurovascular diseases.

Endothelial CXCR7 regulates breast cancer metastasis

Atypical chemokine receptor CXCR7 (ACKR3) functions as a scavenger receptor for chemokine CXCL12, a molecule that promotes multiple steps in tumor growth and metastasis in breast cancer and multiple other malignancies. While normal vascular endothelium expresses low levels of CXCR7, marked upregulation of CXCR7 occurs in tumor vasculature in breast cancer and other tumors. To investigate effects of endothelial CXCR7 in breast cancer, we conditionally deleted this receptor from vascular endothelium of adult mice, generating CXCR7^ΔEND/ΔEND animals. CXCR7^ΔEND/ΔEND mice appeared phenotypically normal, although these animals exhibited a modest 35 ± 3% increase in plasma CXCL12 as compared with control. Using two different syngeneic, orthotopic tumor implant models of breast cancer, we discovered that CXCR7^ΔEND/ΔEND mice had significantly greater local recurrence of cancer following resection, elevated numbers of circulating tumor cells, and more spontaneous metastases. CXCR7^ΔEND/ΔEND mice also showed greater experimental metastases following intracardiac injection of cancer cells. These results establish that endothelial CXCR7 limits breast cancer metastasis at multiple steps in the metastatic cascade, advancing understanding of CXCL12 pathways in tumor environments and informing ongoing drug development targeting CXCR7 in cancer.

MK-0457, an Aurora kinase and BCR-ABL inhibitor, is active in patients with BCR-ABL T315I leukemia

MK-0457, an Aurora kinase and BCR-ABL inhibitor, was studied on a Phase I/II study in 77 patients with refractory hematologic malignancies. The average number of cycles per patient was 3 (range 1-21). Maximum tolerated doses for a 5-day short infusion and continuous infusion regimens were 40 mg/m(2)/h and 144 mg/m(2)/h, respectively. Drug-related adverse events (AEs) included transient mucositis and alopecia. Eight of 18 patients with BCR-ABL T315I-mutated chronic myelogenous leukemia (44%) had hematologic responses and one of three patients (33%) with Philadelphia chromosome-positive acute lymphoblastic leukemia obtained complete remission. MK-0457 has important activity in patients with leukemias expressing the highly resistant T315I BCR-ABL mutation.

Linking the epigenetic 'language' of covalent histone modifications to cancer

Covalent modifications of histones, such as acetylation, methylation, and phosphorylation, and other epigenetic modulations of the chromatin, such as methylation of DNA and ATP-dependent chromatin reorganisation, can play a major part in the multistep process of carcinogenesis, with far-reaching implications for human biology and human health. This review focuses on how aberrant covalent histone modifications may contribute to the development of a variety of human cancers, and discusses the recent findings with regard to potential therapies.

Deciphering cancer complexities in genetically engineered mice

Because the pRb pathway is disrupted in most solid human cancers, we have generated genetically engineered mouse cancer models by inactivating pRb function in several cell types, including astrocytes and mammary, prostate, ovarian, and brain choroid plexus epithelia. In every case, proliferation and apoptosis are acutely induced, predisposing to malignancy. Cell type dictates the pathways involved in tumor progression. In the astrocytoma model, we developed strategies to induce events in the adult brain, either throughout the tissue or focally. Both K-Ras activation and Pten inactivation play significant roles in progression. In the prostate model, adenocarcinoma progression depends on Pten inactivation. However, nonautonomous induction of p53 in the mesenchyme leads to evolution of both compartments, with p53 loss occurring in the mesenchyme. Thus, studies in these models continue to identify key tumorigenesis mechanisms. Furthermore, we are hopeful that the models will provide useful preclinical systems for diagnostic and therapeutic development.

Differential expression of HOX genes in neoplastic and non-neoplastic human astrocytes

HOX genes are a large family of regulatory genes implicated in the control of developmental processes. HOX genes are involved in malignant transformation and progression of different types of tumour. Despite intensive efforts to delineate the expression profiles of HOX genes in other cell types, nothing is known regarding the global expression profile of these genes in normal human astrocytes and astrocytomas. The present study has analysed the expression profile of the 39 class I HOX genes in normal human astrocytes (NHA and E6/E7), two well-established glioblastoma cell lines (U-87 MG and U-1242-MG), as well as neoplastic (WHO grades II/III and IV) and non-neoplastic temporal lobe specimens with hippocampal sclerosis and medically intractable epilepsy. RT-PCR, quantitative real-time PCR, immunocytochemistry, and western blot analyses revealed differential expression of nine HOX genes (A6, A7, A9, A13, B13, D4, D9, D10, and D13) in normal human astrocytic cell lines and non-neoplastic temporal lobe specimens. The data show that HOX genes are differentially expressed in neoplastic and non-neoplastic astrocytes and that multiple HOX genes are overexpressed in glioblastoma cell lines, astrocytomas (II/III), and glioblastoma multiforme. The differential expression of HOX genes in normal and neoplastic astrocytes suggests a role for these genes in brain tumourigenesis.

A phase I clinical and pharmacokinetic (PK) trial of the aurora kinase (AK) inhibitor MK-0457 in cancer patients

3009

Background: The AKs are essential for mitotic progression, spindle formation, centrosome maturation, chromosomal segregation, and cytokinesis. Elevated expression occurs frequently in tumors. MK-0457 (VX-680) is a potent AK inhibitor, with Ki values of 0.66, 18 and 4.6 nM for AKs A, B and C, respectively. MK-0457 inhibits proliferation of transformed cells in vitro (IC50’s 15–113 nM), and induces colon and pancreatic cancer xenograft regressions. Methods: After IRB approval, consenting patients (pts) with refractory solid tumors (median 3 prior regimens, range 2–6) and adequate hematologic and organ function were enrolled using an accelerated dose escalation scheme with 1–2 pts/dose level until ≥ grade 2 toxicity, followed by 3–6 pts/level. MK-0457 was administered by continuous 5-day intravenous infusion every 28 days. Dose-limiting toxicity (DLT) was grade 3 non-hematologic or grade 4 hematologic toxicity ≥ 5 days, or grade 4 febrile neutropenia (FN) during cycle 1. PKs were collected pre-dose through 168 h and analyzed for MK-0457 and metabolites by HPLC/mass spec. Steady state volume of distribution (Vdss), clearance (CL), maximal concentration (Cmax) and terminal half-life (t1/2) were determined by WinNonLin. Results: 16 pts received MK-0457 dosed at 0.5, 1, 2, 4, 8, and 12 mg/m2/h. Median number of cycles was 2 (range 1–6). DLT was asymptomatic neutropenia ≥ 5 days at 12 mg/m2/h. At 8 mg/m2/h, 1 pt experienced FN in cycle 2; a second developed a grade 2 allergic reaction. Three pts achieved stable disease as best response, and two of them completed 6 cycles. Plasma concentrations reached steady state rapidly (i.e., within 24 h) and declined biexponentially after the end of infusion; after a rapid initial decay, a slower decaying terminal phase demonstrated a t1/2 ∼15 h. PK parameters include Vdss = 237 ± 107 (SD) L/m2 and CL = 517 ± 141 ml/min/m2. At 8 mg/m2/h, Cmax was ∼650 nM. Conclusion: MK-0457 is generally well tolerated and achieves plasma levels similar to those causing regressions in xenografts. CL is high and exposures achieved are roughly dose proportional. Because 8 mg/m2/h was well tolerated in heavily pre-treated pts, escalation to 10 mg/m2/h is underway. Baseline tumor samples will be assessed for predictive biomarkers at the recommended phase II dose.

[Table: see text]

Linking the epigenetic 'language' of covalent histone modifications to cancer

Covalent modifications of histones, such as acetylation, methylation, and phosphorylation, and other epigenetic modulations of the chromatin, such as methylation of DNA and ATP-dependent chromatin reorganisation, can play a major part in the multistep process of carcinogenesis, with far-reaching implications for human biology and human health. This review focuses on how aberrant covalent histone modifications may contribute to the development of a variety of human cancers, and discusses the recent findings with regard to potential therapies.

[Radiotherapy for 308 patients with non-small cell lung cancer (NSCLC)]

BACKGROUND

To analyze the survival results retrospectively of the patients with NSCLC treated by radiotherapy alone and the clinical factors affecting the survival results.

METHODS

Three hundred and eight patients with NSCLC from January, 1985 to December, 1991 were included in this study (stage I, 11 cases; stage II, 68 cases; stage IIIA, 155 cases; stage IIIB, 74 cases). All patients were confirmed by pathology and cytology. They were treated by 10 MV-X ray or cobalt-60, conventionally fractionated, with weekly dose 7-11.5 Gy. In 47 patients of them treatment planning system was used at the beginning or in the middle of radiotherapy as to have the primary lesion and mediastinum in the full course of radiotherapy. In the rest of patients whose mediastinal dose was 40Gy by anterior and posterior fields, irradiation dose to the spinal cord was avoided and irradiation dose to the primary lesion got to the definitive treatment. The survival rate was analyzed by Kaplan-Meier and tested by Log-rank.

RESULTS

The median survival was 10 months. The 1-, 3- and 5-year survival rates were 43%, 15% and 9% respectively. The earlier the clinical stage, the better the prognosis (P=0.0001). The survival rate of the patients with complete remission at the end of radiotherapy was better than that of the patients with residual tumor (P=0.0001). The survival of the patients with weekly dose larger than 10 Gy was better ( P=0.0461). There was no relationship among the survival rate and the total dose and mediastinal dose.

CONCLUSIONS

The results show the survival rate of patient with NSCLC treated by radiotherapy alone was related to clinical stage, instant response and weekly dose, but not to the total dose and the mediastinal dose.

BRCA1 deficient embryonic stem cells display a decreased homologous recombination frequency and an increased frequency of non-homologous recombination that is corrected by expression of a brca1 transgene

BRCA1 is a nuclear phosphoprotein that has been classified as a tumor suppressor based on the fact that women carrying a mutated copy of the BRCA1 gene are at increased risk of developing breast and ovarian cancer. The association of BRCA1 with RAD51 has led to the hypothesis that BRCA1 is involved in DNA repair. We describe here the generation and analysis of murine embryonic stem (ES) cell lines in which both copies of the murine homologue of the human BRCA1 gene have been disrupted by gene targeting. We show that exogenous DNA introduced into these BRCA1 deficient cells by electroporation is randomly integrated into the genome at a significantly higher rate than in wild type ES cells. In contrast, integration of exogenous DNA by homologous recombination occurs in BRCA1 deficient cells at a significantly lower rate than in wild type controls. When BRCA1 expression is re-established at 5-10% of normal levels by introduction of a Brca1 transgene into BRCA1 deficient ES cells, the frequency of random integration is reduced to wild type levels, although the frequency of homologous recombination is not significantly improved. These results suggest that BRCA1 plays a role in determining the response of cells to double stranded DNA breaks.

Progressive degeneration of dopamine system functions after transient cerebral oligemia in rats

A reduction in cerebral blood flow to oligemic levels was achieved in pentobarbital-anesthetized adult rats by clamping both carotid arteries (BCCA) for 60 min. To assess the extent to which the animals' dopaminergic system was affected over an increasing time span, their spontaneous locomotor activity in an unfamiliar environment and in response to the subcutaneous administration of apomorphine was tested at various times after either BCCA or sham operation. Eight to 14 days after the operation, it was possible to observe a diminished locomotor activity in response to apomorphine injection in BCCA as compared with sham-operated animals, while oral stereotypical behavior such as licking was increased. At 3 months, there was only a subtle decrease in apomorphine-induced locomotor activity, and stereotypical behavior was similar in both groups. At 7 months, the BCCA rats covered shorter distances than sham-operated controls during the habituation phase; after apomorphine injection, more stereotypic movements, such as, e.g., sniffing, were observed, and less running. Twelve months after surgery, no further differences could be observed between the two groups during the habituation phase, but the injection of apomorphine led to increased stereotypic sniffing movements, rearing and locomotor activity in BCCA animals to a greater extent than in the controls. At 12 months, sensorimotor disturbances elicited by the rota rod test, which were only transiently observed at 11 weeks and 7 months, did not appear any different from the normal age-related motor decline of the sham-operated controls. The animals' motor co-ordination in the chimney test was not significantly disturbed during the time between 7 and 12 months after surgery. At 15 months, nocturnal locomotor activities in BCCA rats were significantly decreased. In situ hybridization (ISH) histochemistry revealed decreased D1 receptor mRNA (D1RmRNA) in striatal neurons 19 months after surgery, while D2 receptor mRNA (D2RmRNA) and the neuronal number remained the same. The present results show that just as is already known for the immature rat brain, the adult rat brain, too, reacts to a transient decrease in its blood supply by appearance of long-lasting alterations in function, and that even a single oligemic episode is capable of inducing progressive dopaminergic dysfunctions and ultimately the partial loss of striatal D1RmRNA.

[Influences of acetylcholine, glutamic acid and GABA on the neuronal firings in ventromedial thalamic nucleus]

In this study, it was shown that the neuronal spontaneous firings of ventromedial thalamic nucleus (VM) in rats were increased by acetylcholine (ACH) and glutamic acid (GLU) applied microiontophoretically with an intensity-dependent manner. Both gamma-animobutyric acid (GABA) and baclofen inhibited the spontaneous firings in majority of VM neurons, but the effect of GABA was rapid and short-lasting, while that of baclofen was slow and long-lasting. GABA could reverse the effects of ACH and GLU. The majority of VM neuronal firing rates could be enhanced by bicuculine, while atropine and MK801 had little effect. The results indicate an important convergence of GLUergic, GABAergic and cholinergic activities in the same VM neurons and GABAergic activities tonically inhibit the VM neurons.