Role of p53 transcription factor in determining the efficacy of telomerase inhibitors in cancer treatment.

AIM: Telomerase expression is unique to cancer cells, making it a promising target for therapy. However, a major drawback of telomerase inhibition is that it affects cancer cell proliferation only when telomeres shorten, creating a lag phase post-continuous drug treatment. Acute cytotoxicity of telomerase inhibitors is dependent on their ability to induce DNA damage. p53 senses DNA damage and is the primary effector required for sensitizing cells towards apoptosis. MAIN METHODS: Isogenic p53+/+ and p53-/- ovarian cancer cell lines were generated using the CRISPR/Cas9 system and the anti-cancer effect of telomerase inhibitors MST-312 and BIBR1532 were determined. Flow cytometry, real-time PCR, and western blot were performed to study cell cycle, apoptosis, and gene expression. KEY FINDINGS: We report that MST-312 exhibits p53-dependent cytotoxicity, while BIBR1532 exhibits p53-independent cytotoxicity. Colony-forming ability also confirms the p53-dependent effect of MST-312. Re-expression of p53 in p53-/- cells could rescue MST-312 sensitivity. In p53+/+ cells, MST-312 causes S phase arrest and activation of p53-dependent target genes like anti-apoptosis markers (Fas and Puma) and cell cycle markers (p21 and cyclinB). In p53-/- cells, MST-312 causes S/G2/M arrest. BIBR1532 induces S/G2/M phase cell cycle arrest irrespective of p53 status. This correlates with the expression of the DNA damage marker (γ-H2AX). Long-term continuous treatment with MST-312 or BIBR1532 results in p53-independent telomere shortening. SIGNIFICANCE: In summary, we demonstrate that acute anti-cancer effects of MST-312 are dependent on p53 expression. Hence, it is important to consider the p53 expression status in cancer cells when selecting and administering telomerase inhibitors.

Telomerase inhibitor MST-312 and quercetin synergistically inhibit cancer cell proliferation by promoting DNA damage.

Quercetin is a natural flavonoid with well-established anti-proliferative activities against a variety of cancers. Telomerase inhibitor MST-312 also exhibits anti-proliferative effect on various cancer cells independent of its effect on telomere shortening. However, due to their low absorption and toxicity at higher doses, their clinical development is limited. In the present study, we examine the synergistic potential of their combination in cancer cells, which may result in a decrease in the therapeutic dosage of these compounds. We report that MST-312 and quercetin exhibit strong synergism in ovarian cancer cells with combination index range from 0.2 to 0.7. Co-treatment with MST-312 and quercetin upregulates the DNA damage and augments apoptosis when compared to treatment with either compound alone or a vehicle. We also examined the effect of these compounds on the proliferation of normal ovarian surface epithelial cells (OSEs). MST-312 has a cytoprotective impact in OSEs at lower dosages, but is inhibitory at higher doses. Quercetin did not affect the OSEs proliferation at low concentrations while at higher concentrations it is inhibitory. Notably, combination of MST-312 and quercetin had no discernible impact on OSEs. These observations have significant implications for future efforts towards maximizing efficacy in cancer therapeutics as this co-treatment specifically affects cancer cells and reduces the effective dosage of both the compounds.

Long non-coding RNAs at work on telomeres: Functions and implications in cancer therapy.

Long non-coding RNAs (lncRNAs) are known to regulate various biological processes including cancer. Cancer cells possess limitless replicative potential which is attained by telomere length maintenance while normal somatic cells have a limited lifespan because their telomeres shorten with every cell division ultimately triggering replicative senescence. Two lncRNAs have been observed to play a key role in telomere length maintenance. First is the lncRNA TERC (telomerase RNA component) which functions as a template for telomeric DNA synthesis in association with telomerase reverse transcriptase (TERT) which serves as the catalytic component. Together they constitute the telomerase complex which functions as a reverse transcriptase to elongate telomeres. Second lncRNA that helps in regulating telomere length is the telomeric repeat-containing RNA (TERRA) which is transcribed from the subtelomeric region and extends to the telomeric region. TERC and TERRA exhibit important functions in cancer with implications in precision oncology. In this review, we discuss various aspects of these important lncRNAs in humans and their role in cancer along with recent advancements in their anticancer therapeutic application.

Repurposing of drugs: An attractive pharmacological strategy for cancer therapeutics.

Human malignancies are one of the major health-related issues though out the world and anticipated to rise in the future. The development of novel drugs/agents requires a huge amount of cost and time that represents a major challenge for drug discovery. In the last three decades, the number of FDA approved drugs has dropped down and this led to increasing interest in drug reposition or repurposing. The present review focuses on recent concepts and therapeutic opportunities for the utilization of antidiabetics, antibiotics, antifungal, anti-inflammatory, antipsychotic, PDE inhibitors and estrogen receptor antagonist, Antabuse, antiparasitic and cardiovascular agents/drugs as an alternative approach against human malignancies. The repurposing of approved non-cancerous drugs is an effective strategy to develop new therapeutic options for the treatment of cancer patients at an affordable cost in clinics. In the current scenario, most of the countries throughout the globe are unable to meet the medical needs of cancer patients because of the high cost of the available cancerous drugs. Some of these drugs displayed potential anti-cancer activity in preclinic and clinical studies by regulating several key molecular mechanisms and oncogenic pathways in human malignancies. The emerging pieces of evidence indicate that repurposing of drugs is crucial to the faster and cheaper discovery of anti-cancerous drugs.

Gonadotropin and steroid hormones regulate pluripotent very small embryonic-like stem cells in adult mouse uterine endometrium.

BACKGROUND: Very small embryonic-like stem cells (VSELs) exist in adult organs, express pluripotent markers and have the ability to differentiate into three germ layers in vitro. Testicular, ovarian and hematopoietic stem/progenitor cells express receptors for follicle stimulating (FSH) and ovarian hormones and are activated by them to undergo proliferation/differentiation. VSELs exist in mouse uterus and are regulated by physiological dose of estradiol (E) & progesterone (P) during endometrial growth, differentiation and regeneration/remodeling. In the present study, effects of daily administration of E (2 µg/day), P (1 mg/Kg/day) or FSH (5 IU/day) for 7 days on the endometrium and stem/progenitor cells was studied in bilaterally ovariectomized mice. RESULTS: E treatment resulted in hypertrophy whereas P resulted in hyperplasia and overcrowding of epithelial cells. FSH also directly stimulated the endometrial cells. Nuclear OCT-4A positive VSELs were visualized in ovariectomized (atrophied) endometrium and cytoplasmic OCT-4B positive epithelial, stromal and endothelial cells were observed after treatment. FSH treated uterine tissue showed presence of 4 alternately spliced FSHR isoforms by Western blotting. 3-5 µm VSELs with a surface phenotype of LIN-/CD45-/SCA-1+ were enumerated by flow cytometry and were found to express ER, PR, FSHR1 and FSHR3 by RT-PCR analysis. Differential effects of treatment were observed on pluripotent (Oct4A, Sox2, Nanog), progenitors (Oct-4, Sca-1), primordial germ cells (Stella, Fragilis) and proliferation (Pcna) specific transcripts by qRT-PCR analysis. FSH and P (rather than E) exerted profound, direct stimulatory effects on uterine VSELs. Asymmetric, symmetric divisions and clonal expansion of stem/progenitor cells was confirmed by co-expression of OCT-4 and NUMB. CONCLUSIONS: Results confirm presence of VSELs and their regulation by circulatory hormones in mouse uterus. Stem cell activation was more prominent after P and FSH compared to E treatment. The results question whether epithelial cells proliferation is regulated by paracrine influence of stromal cells or due to direct action of hormones on stem cells. VSELs expressing nuclear OCT-4A are the most primitive and pluripotent stem cells, undergo asymmetric cell division to self-renew and differentiate into epithelial, stromal and endothelial cells with cytoplasmic OCT-4B. Role of follicle stimulating and steroid hormones on the stem cells needs to be studied in various uterine pathologies.

Fellow-eye comparison of posterior capsule opacification between 2 aspheric microincision intraocular lenses.

PURPOSE: To compare posterior capsule opacification (PCO) between 2 microincision hydrophilic intraocular lenses (IOLs) and with a conventional spherical hydrophobic IOL. SETTING: St. Thomas' Hospital, London, United Kingdom. DESIGN: Prospective randomized comparative study. METHODS: A microincision Acri.Smart 36A (negatively aspheric) or Akreos MI-60 (aspherically neutral) IOL was randomized to the first eye of patients with the alternative IOL implanted in the fellow eye within 3 weeks. Postoperatively, 100% and 9% logMAR corrected distance visual acuity (CDVA) were assessed. Retroillumination photographs were analyzed using the posterior capsule opacity software system. The data on PCO scores were compared with those of a conventional spherical hydrophobic IOL (Acrysof SN60AT). RESULTS: One hundred percent CDVA was significantly better at 12 months and 9% CDVA was better at 6, 12, and 24 months (P<.05) with the negatively aspheric IOL. One eye in each group with microincision IOLs developed capsule phimosis at 1 month. Neodymium:YAG capsulotomies were required by 2 years in 2 eyes with a negatively aspheric IOL and 8 eyes with an aspherically neutral IOL. At 24 months, the mean PCO score remained less than 10% with the conventional spherical IOL, whereas it increased with time in the negatively aspheric IOL (up to 16%) and the aspherically neutral IOL (up to 23%). CONCLUSIONS: The negatively aspheric IOL had a better PCO profile than the aspherically neutral IOL. This may be attributed to the difference in the edge design between the IOLs. The microincision IOLs had more PCO than the conventional 1-piece hydrophobic IOL.

Comparison of near vision, intraocular lens movement, and depth of focus with accommodating and monofocal intraocular lenses.

PURPOSE: To compare visual acuity, intraocular lens (IOL) movement, and depth of focus with the Crystalens HD single-optic accommodating IOL and the Tecnis ZCB00 aspheric monofocal IOL. SETTING: St. Thomas' Hospital, London, United Kingdom. DESIGN: Prospective randomized controlled trial. METHODS: Patients with bilateral symptomatic cataract had bilateral sequential cataract surgery within 6 weeks with randomized implantation of the accommodating or monofocal IOL in both eyes. Exclusion criteria included other ocular conditions and corneal astigmatism greater than 2.00 diopters. The primary outcome was uniocular distance-corrected near visual acuity (DCNVA). Secondary measures were IOL movement, depth of focus, intermediate and distance vision, objective refraction, and pupil size at distance and near fixation. Results from 3 months postoperatively are presented. RESULTS: Three months postoperatively, 64 patients (32 in each group) were available for study. The distance vision was not statistically significantly different between the accommodating IOL and monofocal IOL (mean 0.05 logMAR versus 0.06 logMAR). The mean DCNVA (0.48 logMAR ± 0.15 [SD] versus 0.61 ± 0.13 logMAR) and intermediate visual acuity (0.08 ± 0.1 logMAR versus 0.20 ± 0.09 logMAR) were significantly better with the accommodating IOL (P<.001). Neither IOL had clinically significant movement, and near vision did not directly correlate with movement of the accommodating IOL. The accommodating IOL provided greater depth of focus. CONCLUSIONS: Near and intermediate acuities were better with the accommodating IOL. This effect was not directly linked to IOL movement but was at least partly due to depth of focus.

Fellow-eye comparison of 2 aspheric microincision intraocular lenses and effect of asphericity on visual performance.

PURPOSE: To evaluate visual performance and aberrations with aspheric and spherically neutral microincision intraocular lenses (IOLs) and assess the influence of asphericity on visual performance, wavefront aberration, and depth of focus. SETTING: St. Thomas' Hospital, London, United Kingdom. DESIGN: Clinical trial and cohort study. METHODS: In the first study, patients with bilateral cataract were randomized to receive an aspheric Acri.Smart 36A IOL or a spherically neutral Akreos MI60 IOL in the first eye. The other IOL was implanted in the second eye within 3 weeks. Assessments at 3 months were 100% and 9% corrected distance visual acuity (CDVA) and distance-corrected near visual acuity (DCNVA). Aberrations and depth of focus were computed using iTrace software. In the second study, data from the other published study was combined to assess the visual performance, aberration, and depth of focus in groups of spherical, spherically neutral, and negatively aspheric (asphericity -0.17 µm) IOLs. RESULTS: In part 1, there was no difference in 100% or 9% CDVA, DCNVA, or depth of focus between the 2 microincision IOLs. Total spherical aberration was lower with the aspheric IOL. In part 2, the CDVA and DCNVA were not different between the spherical (n = 44), spherically neutral (n = 32), or aspheric (n = 76) IOLs. Total spherical (P<.01) and vertical coma aberrations decreased with increasing IOL asphericity (P<.01). Depth of focus (4.0 mm pupil) also decreased with increasing asphericity and was significant between the spherical IOL and aspheric IOLs. The DCNVA did not differ between groups. CONCLUSION: Asphericity of IOLs did not affect distance visual acuity. The difference in depth of focus was significant only between negatively aspheric and spherical IOLs. Asphericity differences up to 20 µm did not influence depth of focus.

Effect of intraocular lens asphericity on posterior capsule opacification between two intraocular lenses with same acrylic material: a fellow-eye study.

PURPOSE: To evaluate intra-individual differences in posterior capsule opacification (PCO) and visual performance between spherical AcrySof SN60AT and an aspheric AcrySof SN60WF intraocular lens (IOL) with a posterior aspheric surface, both of which are made of same hydrophobic acrylic material. SETTING: Ophthalmology Department, St Thomas' Hospital, London, UK. METHODS: In this prospective randomized, fellow-eye comparison, an aspheric IOL, which is 9% thinner in comparison with the spherical IOL, was randomized to the first eye of 47 patients and fellow-eye surgery was performed within 3 weeks. Follow-up was at 1, 3, 6, 12 and 24 months. Corrected logMAR visual acuity (CDVA) was measured at 100% and 9% contrast. After pupil dilation, digital retroillumination photographs were taken and the mean PCO percentage was calculated using poco software at each follow-up visit. RESULTS: At 1, 3, 6, 12 and 24 months, 47 (94 eyes), 44 (88 eyes), 42 (84 eyes) and 41 (82 eyes) patients were followed-up respectively. Hundred per cent and 9% of LogMAR CDVA was not significantly different between the two IOLs (p = NS at all time-points). Percentage area PCO scores (mean ± SD) at 1, 3, 6, 12 and 24 months with the spherical IOL was 5.82 ± 9.89, 7.76 ± 16.83, 7.21 ± 12.46, 9.29 ± 18.25 and 14.39 ± 25.42, respectively, and with an aspheric IOL was 8.91 ± 12.79, 5.97 ± 10.32, 5.15 ± 7.92, 7.68 ± 11.18 and 12.18 ± 20.10, respectively (p = NS at all time-points). CONCLUSIONS: Posterior capsule opacification was not significantly different between the spheric and aspheric IOLs in this fellow-eye, randomized comparison. Additional asphericity on the existing model of IOL does not influence PCO performance.

A randomized intraindividual comparison of the accommodative performance of the bag-in-the-lens intraocular lens in presbyopic eyes.

PURPOSE: To compare the accommodative performance of the Morcher BioComFold Type 89A bag-in-the-lens intraocular lens (IOL) with a conventional in-the-bag control IOL in presbyopic eyes. DESIGN: Prospective, randomized clinical trial with intraindividual comparison. SETTING: Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom. STUDY POPULATION: Fifty-two eyes of 26 patients with bilateral age-related cataracts. INTERVENTION: Phacoemulsification cataract extraction with implantation of a bag-in-the-Lens and a control IOL, the Alcon AcrySof SA60AT (Alcon Laboratories, Fort Worth, Texas, USA), randomized to either eye. MAIN OUTCOME MEASURES: Axial IOL shift stimulated by physiologic (near visual effort) and pharmacologic (pilocarpine and cyclopentolate) accommodative stimulation was measured objectively with partial coherence interferometry. Other outcome measures were objective and subjective accommodation, logarithm of the minimal angle of resolution distance-corrected near visual acuity, and defocus curves. RESULTS: Three months after surgery, axial IOL shift stimulated by near visual effort measured -5.9 ± 10.3 µm in bag-in-the-lens eyes versus -8.4 ± 12.8 µm in control eyes (P = .37), that stimulated by pilocarpine measured 20.2 ± 165.6 µm versus 50.4 ± 164.4 µm (P = .36), and that stimulated by cyclopentolate measured -65.8 ± 64.3 µm versus -54.0 ± 37.5 µm (P = .34), respectively (n = 25). Objective accommodation measured 0.03 ± 0.18 diopters (D) in bag-in-the-lens eyes versus 0.08 ± 0.21 D in control eyes (P = .40), whereas subjective accommodation measured 2.48 ± 0.72 D versus 2.45 ± 0.80 D (P = .75), respectively. Distance-corrected near visual acuity and defocus curves showed no difference between IOLs. CONCLUSIONS: The bag-in-the-lens IOL demonstrated negligible axial shift and objective accommodation with physiologic near visual stimulation. The IOL shift demonstrated with pilocarpine also was clinically insignificant. The bag-in-the-lens IOL showed no accommodative or near visual advantage over a conventional in-the-bag IOL, despite its unique capsular fixation method. This provides further evidence that the focus-shift principle fails to produce clinically significant IOL movement.