Acridine Orange Flow Cytometry Research Articles

Deciphering the potential of a novel cytostatic autophagy modulator for the treatment of brain cancer along with reduction in brain inflammation

Background and Purpose: Glioblastoma multiforme (GBM) is the most aggressive form of brain tumor, with significant failure of current treatment options, with the five-year survival rate of GBM being less than 7%. Temozolomide (TMZ), the standard chemotherapy, leads to severe toxicity, whereas radiation therapy leads to necrosis. Moreover, GBM leads to severe neuroinflammation, leading to severe fatalities and, thus, poor quality of life in patients. Therefore, owing to the pressing need for safer treatment alternatives, we repurposed a novel FDA-approved acetamide, BRZ, which not only exhibited a significant curbing of GBM progression but also reduced neuroinflammation. Thus, our study provides a treatment option that can also lead to better quality of life in GBM patients. Methods: Sulfarhodamine B cytotoxicity assay was performed on human (SF268, SF295, SF188) and murine (CT2A-LUC) GBM cell lines for both BRZ and TMZ. In the quest for figuring out the mode of cell-growth suppression, we performed annexin and acridine orange flow cytometry assays along with b-galactosidase cellular senescence staining assay. Cellular staining was also confirmed using confocal microscopy. Oncogenic modulation due to BRZ was studied by performing western blotting. In order to study the effect of BRZ on neuroinflammation, we examined the modulation of different neuroinflammatory genes on LPS-stimulated human and murine microglia using RT-qPCR and western blotting. We corroborated our in vitro findings by investigating the tumor progression in intracranially-injected GBM tumors in C57/BL6 mice. Mice weight and organ weights were recorded for both vehicle and BRZ-treated mice to assess toxicity profiles. Results: BRZ exhibited ~300 times more cytotoxicity in GBM cells as compared to TMZ, making it a more potent treatment option. BRZ lead to an increase in acridine orange in a concentration-dependent manner, hinting towards autophagic cell death. b-galactosidase staining assay and confocal microscopy exhibited a dose-dependent increase in b-galactosidase, showcasing a probable cytostatic effect. Expression of autophagic markers such as Atg5, Atg101, LC3A/B, and senescence markers b-galactosidase, p16, and p21 were increased due to BRZ confirming a cytostatic autophagic modulation in GBM cells. Immunoblotting revealed oncogenic modulation due to BRZ wherein Notch-1, Gli-1, Akt, and p-STAT3 were significantly downregulated, as observed in western blotting. Neuroinflammatory genes such as CXCL10, IL6, and ISG15 were downregulated in LPS-stimulated microglia using BRZ in a concentration-dependent manner, hinting towards the potential of BRZ in brain inflammation. BRZ significantly reduced the progression of orthotopic GBM tumors in C57/BL6 mice. There was no significant difference observed in body and organ weights in the vehicle and BRZ-treated mice, hinting toward the safety profile of BRZ. Conclusions and future direction: Our study provides a novel and safer treatment option for GBM in the form of a cytostatic autophagy modulator, BRZ, which also reduces neuroinflammation with the potential to increase patient’s quality of life. In the future, we aim to perform ex vivo analyses of mice brain tumors and perform the neuroinflammation study in GBM mice. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Inhibition of PIM Kinases Mitigates DNA Repair Responses Following Anthracycline-Induced DNA Damage and Enhances the Anti-Tumor Activity of Doxorubicin Against Lymphoma Cells

The PIM kinases are a family of proteins recently identified as promising therapeutic targets in several cancers, including pancreatic, B-cell malignancies, acute leukemia, and prostate cancer among others. The family of PIM kinases is composed of three different members (PIM-1, -2, and -3) that are short-lived serine/threonine kinases involved in the regulation of a number of cellular pathways that are important for cancer cell growth and survival. The PIM kinases show high homology with each other, and exhibit functional redundancy in vitro and in vivo. Overexpression of PIM kinases promotes tumor growth through activation of several key cell-cycle progression and anti-apoptotic proteins, including BAD, p21, p27KIP, c-Myc, and AKT-1. Recently, overexpression of PIM-2 has been shown to have a protective effect against ultraviolet light induced DNA damage (Zirkin et al. J Biol Chem288:21770-83, 2013). We investigated the protective role of PIM kinases in chemotherapy-induced DNA damage, and whether inhibition of PIM kinases enhances anthracycline-induced DNA damage by inhibiting DNA repair, thus enhancing cell death in lymphoma cells lines.Using immunobloting and RT-PCR, we found similarly low levels of PIM-1 and PIM-3, but a wide range of PIM-2 expression, in a panel of non-Hodgkin lymphoma (NHL) cell lines, including Raji, HS Sultan, Daudi, Farage, Granta519, and Toledo. Treatment of cells with doxorubicin (200-400 nM) resulted in up to a five fold increase gene transcription and expression of PIM-1 and PIM-2, which was maximal at 6 hours, and was associated with an increase in DNA damage as detected using acridine orange flow cytometry assay. We also tested the single agent effect of the pan-PIM kinase inhibitor, CX6258 on the cell lines. CX6258 alone inhibited cell growth in all NHL cell lines with varying degrees of potency with IC50ranging from 0.2 – 12.9 µM. The anti-cancer was associated most with PIM-2 expression, with the most sensitive cell lines, Daudi and Toledo, expressing the most PIM-2. Suppression of PIM-2 expression by shRNA significantly decreased proliferation, indicating that PIM-2 is a significant factor in cell growth. Treatment of NHL cells with CX6258 resulted in increased caspase-3 activation and PARP cleavage, decreased BAD phosphorylation, and apoptosis. Treatment with CX6258 also increased expression of p21, decreased expression of cyclins A1 and B1, and induced G2-M cell cycle arrest. The effect of combinations of CX6258 (5-50 µM) and doxorubicin (50-500 nM) on DNA damage and cell death was tested on HS sultan and Daudi cells. While doxorubicin alone resulted in a two-fold increase in DNA damage, this was significantly increased in the presence of CX6258 (12 fold). The addition of CX6258 inhibited the phosphorylation of the DNA repair proteins H2.AX, ATM, and Chk2 that occurred when the cells were treated with doxorubicin alone. The combination of CX6258 and doxorubicin was synergistic in inducing lymphoma cell death, with combination indexes ranging from 0.32-0.85.Our findings suggest a mechanism for synergy where doxorubicin damages cellular DNA and initiates the DNA damage response, while CX6258 inhibits the upregulated PIM kinases from activating the proteins involved in the response. This synergistic anti-tumor activity is further strengthened by the CX6258 inhibition of cell cycle progression and anti-apoptotic proteins activated by the PIM kinases. Taken together, our results provide pre-clinical rationale for clinical testing of PIM kinase inhibitors in combination with doxorubicin in patients with NHL. It also suggests that CX6258 may similarly enhance the anti-cancer effects of other DNA damaging agents. DisclosuresNo relevant conflicts of interest to declare.

In vitro fertilization–intracytoplasmic sperm injection outcome in patients with a markedly high DNA fragmentation index (>50%)

To investigate differences in fertilization, clinical pregnancy, and miscarriage rates between men with a markedly high sperm DNA fragmentation index (DFI) (>50%) and those with low DFI (≤ 15%) in couples matched by female partner age and ovarian reserve as determined by antimüllerian hormone (AMH) level. Retrospective cohort study. University-affiliated fertility center. Men undergoing intracytoplasmic sperm injection (ICSI) cycles who had low (n = 114) or markedly high (n = 36) DNA damage. None. Sperm DNA damage evaluated by acridine orange flow cytometry and expressed as the DFI, with the potential confounders of ovarian reserve and age controlled for by multivariable logistic regression analysis. The fertilization and clinical pregnancy rates were not different between the two groups. We observed a trend toward a higher miscarriage rate with the high DFI group, but it did not reach statistical significance. Intracytoplasmic sperm injection in men with a high DFI with sperm selected by movement and morphology characteristics resulted in a similar pregnancy rate compared with the controls with a normal DFI. However, the trend observed of an increase in miscarriages suggests that any potential negative impact may appear later in development. Future studies involving a larger cohort may determine if the miscarriage trend reaches statistical significance.

Modulation of prostate carcinoma cell growth and apoptosis by chromogranin A.

We elucidated the effect and possible pathways of chromogranin A in regulating prostatic cancer cell growth. Chromogranin A expression in prostatic cancer cell lines were detected with immunofluorescence flow cytometry (FCM) and the inhibition of cell growth due to chromogranin A antibody was measured using microculture tetrazolium. Cell cycle and RNA changes were evaluated with acridine orange FCM. Intracellular chromogranin A variations were detected with FCM, as were apoptotic changes, p53, Fas and tumor necrosis factor-alpha. Apoptosis and caspase-3 expression of tumor cells was assessed with dual immunohistochemical staining. Increased chromogranin A expression was observed in PC-3, DU145 and LNCap cells independent of hormone dependence. Dose and time dependent growth inhibition occurred at 12 hours. Chromogranin A antibody arrested PC3 cells in the S-phase immediately after treatment. The number of G0/G1 and G2/M cells subsequently decreased. PC3 tumor cells had transiently increased RNA at 12 hours with a marked decrease at 48 hours. Decreasing chromogranin A expression started at 12 hours and was most prominent at 48 hours. Apoptotic cells markedly increased at 12 hours with an increase in p53, Fas and tumor necrosis factor-alpha (Fas more than the others). Increased apoptotic cell and caspase-3 expression was observed on immunohistochemical stains. Chromogranin A is an important neuropeptide regulating the growth of prostate cancer cells. Specific antibodies can suppress its function through apoptotic pathways (Fas and caspase-3), leading to programmed cell death. Chromogranin A antibody mediated apoptosis may be a specific alternative treatment for prostate cancer.

In vivo effects of vitamin D on the proliferation and differentiation of rat keratinocytes.

The hormonal form of vitamin D appears to be a physiological regulator of the epidermogenesis. While its differentiation-promoting effect is well accepted, there are conflicting reports of its action on keratinocyte proliferation. This study evaluates the specific changes induced by vitamin D treatment in the epidermis of rats nutritionally deprived of vitamin D by cell size analysis, acridine orange flowcytometry, and the immunohistochemical detection of proteins related to the different stages of differentiation (epidermal calcium binding protein and suprabasal keratins recognized by KL1 antibody) The total keratinocyte and isolated keratinocyte subpopulations were studied. Vitamin D deficiency was associated in the total population with a lower percentage of actively proliferating cells and with a lack of differentiation markers. Study of the isolated cell populations demonstrated, however, that small cells were actively proliferating, whereas they were mainly in the resting stage in the normal epidermis. Treatment with vitamin D dramatically increased cell proliferation and stimulated the appearance of differentiation markers. Some of the observed effects, such as an increase in proliferation and the appearance of epidermal calcium binding protein, were due to the normalisation of the vitamin D deficiency-induced hypocalcemia, whereas the expression of suprabasal keratins was directly dependent on vitamin D. We conclude that the action of vitamin D on the epidermis is associated with increases in both proliferation and differentiation of keratinocytes. Vitamin D itself and its resulting action on calcium homeostasis appear to contribute to the observed effects.

Synthesis of and response to 1,25 dihydroxycholecalciferol by subpopulations of murine epidermal keratinocytes: existence of a paracrine system for 1,25 dihydroxycholecalciferol.

The epidermis is both a target tissue for and a source of 1,25 dihydroxycholecalciferol. The present study determines which of the epidermal cell populations synthesizes 1,25 dihydroxycholecalciferol and which responds to this hormone. Epidermal keratinocytes from new born rat epidermis were separated by unit gravity sedimentation into poorly differentiated cells, slow-cycling more differentiated cells, actively proliferating cells, and terminally differentiating subpopulations. The keratinocyte populations were characterized by cell size analysis, cell morphology, and DNA and RNA contents (acridine orange flow cytometry). 1,25(OH)2D3 synthesis was studied by measuring the conversion of [3H] 25(OH)D3 to [3H] 1,25(OH)2D3. The purified product was tested for its ability to compete with synthetic [3H] 1,25(OH)2D3 for binding to chick intestinal cytosol. The responses of the keratinocyte subpopulations to exogenous 1,25(OH)2D3 were evaluated by the increase in 25(OH)D3-24 hydroxylase activity. Furthermore the expression of 1,25(OH)2D3 receptors (VDR) was examined in these cell populations. The results show that only the least differentiated cells produced 1,25(OH)2D3. In contrast, immunocytochemical detection of VDR, the VDR mRNA, and a 25(OH)D3-24 hydroxylase response to 1,25(OH)2D3 were mainly found in the more differentiated cells. Thus, the ability of epidermis to synthesize 1,25(OH)2D3 and be simultaneously sensitive to it depends on the state of cell differentiation. This suggests that the mammalian epidermis contains a paracrine system in which the more differentiated keratinocytes are sensitive to the 1,25(OH)2D3 produced locally by neighboring immature ones.

The use of fluorescent halo assay and acridine orange flow cytometry to predict intrinsic radiosensitivity, radiation-induced dna damage and repair in human tumor cells

The use of fluorescent halo assay and acridine orange flow cytometry to predict intrinsic radiosensitivity, radiation-induced dna damage and repair in human tumor cells

Cell size and RNA content correlate with cell differentiation and proliferative capacity of rat keratinocytes

Keratinocytes from rat skin were separated according to their size in a specially designed unit-gravity sedimentation chamber. The fractions obtained with this technique showed clear morphological differences, and analysis of size distribution confirmed that size was the criterion for separation. Simultaneous DNA and RNA staining of the fractions with acridine orange and subsequent flow cytometric analysis enabled one to classify cells into resting, proliferating, and differentiating stages. Cell size was not directly correlated with proliferation in situ as determined with acridine orange flow cytometry, nor with proliferative capacity in culture as assayed by BrdU/Hoechst flow cytometry. The smallest cells, exhibiting low DNA and RNA content, which do not proliferate in vivo, required a prolonged period of serum stimulation in vitro to initiate RNA and DNA synthesis. Cells of intermediate size exhibited early RNA synthesis and maximal proliferative capacity, whereas the largest cell population displayed no RNA synthesis in culture and the least proliferative capacity. In conclusion, these results suggest that RNA synthesis early after serum stimulation, in addition to a specific, optimal cell size, correlates with the proliferative capacity of keratinocytes in cell culture.

Altered nucleic acid contents of mononuclear cells in blood of renal allograft recipients

The DNA and RNA contents of blood mononuclear cell populations of 29 cadaver renal allograft recipients and 49 blood donors (controls) were estimated by acridine orange flow cytometry (AO FCM) to assess their cell cycle status. All patients received azathioprine and prednisone for immunosuppression. The patients represented three clinical categories: clinically stable patients, those with acute rejections (clinically overt or impending), and those with infections. Three cell cycle compartments were analyzed for percentage (%) and RNA content (R) of cells: G0/1, consisting of all cells with diploid DNA content; 2 S.D., consisting of cells with diploid DNA content and RNA content 2 standard deviations above the mean RNA content of controls; and SG2M, consisting of cells with a DNA content higher than that of G0/1 cells. The relative coefficient of variation (rCV) of the DNA distribution of G0/1 cells was also determined. In such cell cycle evaluations, the means of rCV and SG2M% of stable recipients were significantly different from those of blood donors. Multivariate analysis of the variables of the three categories of patients resulted in the tentative formulation of two simple logistic equations: one that differentiates stable patients from those with impending or overt rejections based on 2SD% and another one that distinguishes infected patients from those with impending or overt rejections based on SG2M% and RG0/1.

DNA Flow Cytometry of Thyroid Neoplasms

Mechanically dispersed cell suspensions from 23 thyroid lesions were studied by acridine orange flow cytometry. Eight of 14 carcinomas (three papillary, two medullary, two Hürthle cell, and one follicular) manifested abnormal DNA indices ranging from 0.6 to 2.0. Six carcinomas (four papillary and two medullary) were diploid. Four patients having papillary carcinomas with diploid DNA content were young women whose clinical course of disease was indolent. Three papillary carcinomas with abnormal DNA content were found in older men with clinically aggressive disease. One benign adenomatoid nodule displayed a small population with a low-degree hyperdiploid stemline (DNA index = 1.1) with low proliferative activity. Differentiation between clinically indolent and aggressive carcinomas may be possible by nuclear DNA determination, but further work is needed to determine the importance of proliferative activity in thyroid carcinoma.

Discrimination of human leukemia subtypes by flow cytometric analysis of cellular DNA and RNA

A newly developed flow cytometry technique for simultaneous measurements of three features of individual cells--DNA, RNA, and nuclear diameter--using acridine orange as a fluorescent metachromatic dye, has been applied to cell-cycle analysis. DNA stemline determination, and to classification of 102 cases of human leukemias in adults. Acute lymphoblastic leukemia (L1–2) was characterized by moderately increased RNA of G0/1 cells as compared to normal lymphocytes; acute nonlymphoblastic leukemia (M 1–5) by very high RNA of G0/G1 cells. Both had either diploid or aneuploid DNA stemlines. Chronic lymphocytic leukemia showed diploid DNA, very low proliferation, and low RNA, similar to that found by use to be typical for normal B cells. In chronic myelogenous leukemia, two cell populations were distinguished, one with high RNA, the other with very low RNA and elongated nuclear diameter due to stripped, unfolded nuclei of polymorphonuclear leukocytes. The number of leukemic blast cells, identified by aneuploid DNA values, correlates well with conventional microscopy counts and could be followed during the course of treatment. Thus, acridine orange flow cytometry can be used to discriminate subtypes of human leukemias, to determine cell cycle stages, and to detect and monitor aneuploid leukemia stemlines.

Discrimination of Human Leukemia Subtypes by Flow Cytometric Analysis of Cellular DNA and RNA

A newly developed flow cytometry technique for simultaneous measurements of three features of individual cells--DNA, RNA, and nuclear diameter--using acridine orange as a fluorescent metachromatic dye, has been applied to cell-cycle analysis. DNA stemline determination, and to classification of 102 cases of human leukemias in adults. Acute lymphoblastic leukemia (L1-2) was characterized by moderately increased RNA of G0/1 cells as compared to normal lymphocytes; acute nonlymphoblastic leukemia (M 1-5) by very high RNA of G0/G1 cells. Both had either diploid or aneuploid DNA stemlines. Chronic lymphocytic leukemia showed diploid DNA, very low proliferation, and low RNA, similar to that found by use to be typical for normal B cells. In chronic myelogenous leukemia, two cell populations were distinguished, one with high RNA, the other with very low RNA and elongated nuclear diameter due to stripped, unfolded nuclei of polymorphonuclear leukocytes. The number of leukemic blast cells, identified by aneuploid DNA values, correlates well with conventional microscopy counts and could be followed during the course of treatment. Thus, acridine orange flow cytometry can be used to discriminate subtypes of human leukemias, to determine cell cycle stages, and to detect and monitor aneuploid leukemia stemlines.