P–229 Oxidative stress and Metformin; an in-vitro study on serum and primary human granulosa cell cultures

Study question

What is the effect of administration of Metformin on the oxidative stress (OS) levels in serum and primary human granulosa cell cultures of infertile females?

Summary answer

Metformin suppresses oxidative stress in serum and human granulosa cells and increases the expression of SIRT1 in OS induced environment.

What is known already

Oxidative stress (OS) is a resultant of mitochondrial dysfunction when it either fails to fight against the oxidants or the expression of the antioxidants is not sufficient. Cellular damage including DNA damage is a common resultant of oxidative stress. OS effects the oocyte maturation and moreover, the cleavage phase in the early embryonic stage. The raised levels of OS makers are hypothesized to compromise the nuclear maturation and the mitotic spindles of the maturing oocytes. Metformin seemed to decrease oxidative stress and improve insulin resistance, dyslipidaemia and endothelial dysfunction in PCOS patients

Study design, size, duration

This cross-sectional study was conducted from August 2017 – July 2019, at Aga Khan Hospital in collaboration with Australian Concept Infertility Medical Centre (ACIMC) on ten infertile patients undergoing egg retrieval after ethical approval from of Aga Khan Hospital (AKU-ERC–2018–0557–601).

Participants/materials, setting, methods

Serum samples were obtained and analysed. Follicular fluid of these subjects was collected for establishment of primary cell culture model of normal human granulosa cells (hGCs). Serum and hGC cultures were grouped as; a) control: treatment, b) Test1: H2O2 induced OS, and c) Test2: H2O2 induced OS treated with metformin. OS was estimated in all groups by Mishra method. The two Test groups were assessed for SIRT1 levels using quantitative PCR employing SIRT1 specific primers

Main results and the role of chance

With mean age of 32.04 ± 2.29 years the mean BMI was 27.61 ± 2.15 kg/m2. OS was induced and measured by an increase in optical density (OD) in hGC Test samples which showed 0.28 (0.16–0.40) OD when compared with control hGC samples 0.153 (0.09–0.23). There was a significant reduction in ODs after metformin treatment in the stress induced cells 0.182 (0.05–0.30). A similar pattern was observed in the serum samples in ODs; control: 0.105 (0.09–0.15), stress induced samples: 0.199 (0.19–0.20). and stress induced serum sample with metformin treatment: 0.1415 (0.06–0.18).

The Ct values obtained to express the effect of metformin on SIRT1 levels, for OS induced (Test1) and OS induced metformin treated (Test2) cells were found to be 29.12 and 26.42, respectively. We also observed a significant (85%) difference in the fold change of SIRT1 expression between metformin treated and untreated cells.

Limitations, reasons for caution

Small sample size is the limitation of this study. The impact of metformin on cell cultures due to different causes of infertility could not be ascertained

Wider implications of the findings: Metformin suppresses oxidative stress in serum and human granulosa cells and increases the expression of SIRT1 in OS induced environment, therefore, metformin may be considered as a treatment of oxidative stress in infertile patients. Randomized control trial with large sample size is recommended to confirm the cause and effect relationship.

Trial registration number

Not applicable

Safe ablation of the anal mucosa and perianal skin in rats using Photodynamic Therapy--a promising approach for treating Anal Intraepithelial Neoplasia

BACKGROUND

Anal Intraepithelial Neoplasia (AIN), a pre-cursor of anal squamous carcinoma, is increasingly detected in individuals with impaired immune function. However, choices for effective, low morbidity treatment are limited. Photodynamic Therapy (PDT) is promising as it is known to ablate more proximal gastrointestinal mucosa with safe healing, without damage to underlying muscle. It can also ablate skin with safe healing and minimal scarring.

METHODS

Pharmacokinetics: Normal rats were sensitised with 200mg/kg 5-aminolaevulinic acid (ALA) and killed 1-8h later. Anal tissues were examined by fluorescence microscopy to quantify the concentration of PPIX (protoporphyrin IX, the active derivative of ALA) in anal mucosa and in the underlying sphincter. PDT: Normal rats were sensitised similarly 3h later, laser light (635 nm) was delivered. Anal canal: 50-150 J/cm using 1cm diffuser fibre; for peri-anal skin, 50-200 J/cm(2), using microlens fibre. In each group, 2 rats were killed 3, 7, 14 and 28 days later and the anal region removed for histological examination.

RESULTS

Pharmacokinetics: Peak concentration of PPIX in mucosa was at 3h, peak ratio mucosa: muscle, 6, seen at same time. PDT. Anal canal 50 J/cm: complete mucosal ablation by 3 days, complete regeneration by 28 days. Higher energies caused muscle damage with scarring. Peri-anal skin: 200 J/cm(2); complete ablation of skin, including appendages, complete healing by 28 days. Minimal effect with lower energy.

CONCLUSION

ALA-PDT can ablate anal mucosa and peri-anal skin with safe healing and no underlying damage. However, over treatment can damage the sphincters. This technique is ready to undergo clinical trials.

Abstract B190: Efficacy of the specific ETA receptor antagonist zibotentan (ZD4054) in cancer cells and fibroblasts from colorectal cancer

Endothelin-1 (ET-1) contributes to growth and progression of solid cancers, mainly through endothelin receptor A (ETAR). Therefore endothelin receptor antagonism is emerging as a potential treatment for neoplasms. We evaluated the efficacy of the specific ETAR antagonist zibotentan (ZD4054) in blocking ET-driven cellular effects in colorectal cancer (CRC). CRC cell lines (HT29, SW620) and primary normal fibroblast strains isolated from human colorectal tissues (CF36, CF56, CF65, CF75) were incubated in ET-1 with/without BQ123, zibotentan (ETAR antagonists), BQ788 (ETBR antagonist). Resultant cell growth was measured by the colourimetric methylene blue assay; migration by a modified monolayer scratch assay; contraction in collagen gels; downstream effectors by western blotting. ET-1 driven growth (18%–45% above control) was significantly inhibited (p<0.01) by ETAR (not ETBR) antagonism (BQ123=zibotentan CRC; fibroblasts). ET-1 driven fibroblast migration and contraction were blocked by ETAR and ETBR antagonism (zibotentan=BQ123). CRC cells did not migrate or contract. ET-1-stimulated expression of downstream effectors was driven by ETAR or ETBR, eg: (1) connective tissue growth factor (CTGF) was blocked by ETAR antagonism (zibotentan>BQ123; CRC and fibroblasts); (2) collagen XI was blocked by ETAR>ETBR antagonism (zibotentan>BQ123; fibroblasts). The specific ETAR antagonist zibotentan is at least as efficacious as BQ123 in blocking ET-1 driven growth, migration and contraction both in CRC cells and colorectal fibroblasts, which form the supporting tumor stroma. Zibotentan is a strong candidate for adjuvant treatment in CRC.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B190.

Photochemical internalisation of chemotherapy potentiates killing of multidrug-resistant breast and bladder cancer cells

Multidrug resistance (MDR) is the major confounding factor in adjuvant solid tumour chemotherapy. Increasing intracellular amounts of chemotherapeutics to circumvent MDR may be achieved by a novel delivery method, photochemical internalisation (PCI). PCI consists of the co-administration of drug and photosensitiser; upon light activation the latter induces intracellular release of organelle-bound drug. We investigated whether co-administration of hypericin (photosensitiser) with mitoxantrone (MTZ, chemotherapeutic) plus illumination potentiates cytotoxicity in MDR cancer cells. We mapped the extent of intracellular co-localisation of drug/photosensitiser. We determined whether PCI altered drug-excreting efflux pump P-glycoprotein (Pgp) expression or function in MDR cells. Bladder and breast cancer cells and their Pgp-overexpressing MDR subclones (MGHU1, MGHU1/R, MCF-7, MCF-7/R) were given hypericin/MTZ combinations, with/without blue-light illumination. Pilot experiments determined appropriate sublethal doses for each. Viability was determined by the 3-[4,5-dimethylthiazolyl]-2,5-diphenyltetrazolium bromide assay. Intracellular localisation was mapped by confocal microscopy. Pgp expression was detected by immunofluorescence and Pgp function investigated by Rhodamine123 efflux on confocal microscopy. MTZ alone (0.1–0.2 μg ml⁻¹) killed up to 89% of drug-sensitive cells; MDR cells exhibited less cytotoxicity (6–28%). Hypericin (0.1–0.2 μM) effects were similar for all cells; light illumination caused none or minimal toxicity. In combination, MTZ /hypericin plus illumination, potentiated MDR cell killing, vs hypericin or MTZ alone. (MGHU1/R: 38.65 and 36.63% increase, P<0.05; MCF-7/R: 80.2 and 46.1% increase, P<0.001). Illumination of combined MTZ/hypericin increased killing by 28.15% (P<0.05 MGHU1/R) compared to dark controls. Intracytoplasmic vesicular co-localisation of MTZ/hypericin was evident before illumination and at serial times post-illumination. MTZ was always found in sensitive cell nuclei, but not in dark resistant cell nuclei. In illuminated resistant cells there was some mobilisation of MTZ into the nucleus. Pgp expression remained unchanged, regardless of drug exposure. Pgp efflux was blocked by the Pgp inhibitor verapamil (positive control) but not impeded by hypericin. The increased killing of MDR cancer cells demonstrated is consistent with PCI. PCI is a promising technique for enhancing treatment efficacy.

Aspergillus fumigatus strains recovered from immunocompromised patients (ICP): subtyping of strains by RAPD analysis

Invasive pulmonary aspergillosis in immunocompromised patients (ICP) is the second most frequent opportunistic fungal infection. The causative organism includes 16 species of Aspergillus, of which A. fumigatus dominates the ubiquitous incidence of invasive or allergic broncho-pulmonary aspergillosis (ABPA). The definitive diagnosis of invasive aspergillosis is difficult. We have analyzed 24 strains of A. fumigatus recovered from ICP using the RAPD technique. The profiles generated with the 20 primers tested were mostly unique. These results may have a profound impact on the management of aspergillosis, especially in the ICP.

RAPD profile variation amongst provenances of neem

Neem, described as a tree for solving global problems, is an evergreen, long-lived, multipurpose tree of the tropics with a wide distribution range in India. It is believed to be highly cross-pollinated. Inter-provenance variations have been reported in neem in case of morphological and physiological characters. Yet no reports about the genetic determinism for these variations are available to our knowledge. In order to have an idea about the extent and/or nature of genetic (DNA) variation in neem, the powerful RAPD technique has been employed. RAPD profiles of 34 accessions/provenances of neem were generated with 200 decamer random primers, of which the data from the 49 primers, that resulted in reproducible amplification products, were considered for analysis. Based on the presence/absence of bands, a similarity matrix was computed. Dendrogram was constructed by UPGMA method based on the pairwise similarities amongst the RAPD profiles. The similarities in RAPD profiles amongst the different DNAs was more than that expected due to the cross-pollinated nature of the tree and furthermore, these more-than-expected similarities were not due to random chance. These results suggest that neem may have a narrow genetic base.

RAPD analysis of Candida albicans strains recovered from different immunocompromised patients (ICP) reveals an apparently non-random infectivity of the strains

The opportunistic imperfect fungus Candida albicans causing life-threatening infections in immunocompromised patients (ICP), especially in HIV-positive cases, is recognized to be one of the most important nosocomial pathogens in the recent decades. The extent of strain-to-strain variation within a species and its relationship to the ability of the organism to colonize or invade a specific group of patients or even a body site is, however, not well known. We have analysed 19 strains of C. albicans recovered from ICP at different locales and times, employing the RAPD technique. No two strains generated identical RAPD profiles with any of the 21 primers tested. Further, the UPGMA clustering of the strains seemingly reflected a certain relationship or nonrandomness in the infection of the patients with the strain of C. albicans vis-a-vis the immunocompromised status due to underlying disease such as diabetes, cancer, asthma and meningitis. These results may have a profound impact on the management of candidiasis, especially in the ICP.