The Dietary Isoprenoid Perillyl Alcohol Inhibits Telomerase Activity in Prostate Cancer Cells

This is the first evidence that a plant-derived compound–perillyl alcohol regulates telomerase activity via the mammalian target of rapamycin (mTOR) pathway in prostate cancer cells. Telomerase–the enzyme responsible for immortalizing cells through telomeric repeats addition–is de-repressed early in an aspiring cancer cell. We hypothesized that perillyl alcohol regulates hTERT (human telomerase reverse transcriptase) at the translational and post-translational levels via its effects on the mTOR pathway. A rapid suppression of telomerase activity was detected in prostate cancer cell lines (PC-3 and DU145) in response to biologically-relevant concentrations and short incubations of perillyl alcohol or the mTOR inhibitor—rapamycin. Western blot analysis revealed a decrease in hTERT protein levels in response to either agent that did not coincide wholly, with loss of telomerase activity suggesting a further level of regulation. Using immunoprecipitation we established the presence of a hTERT-mTOR-S6K (p70 S6 kinase)-Hsp90 (Heat shock protein 90)-Akt complex previously detected in activated NK cells in DU145 prostate cancer cells. Further, western blot analysis demonstrated that perillyl alcohol or rapamycin disrupted the binding interactions between RAPTOR and hTERT, mTOR, S6K, and Hsp90, establishing an additional mechanism by which these agents decrease telomerase activity. Prostate cancer cells overexpress eIF4E (eukaryotic initiation factor 4E) the rate-limiting protein that mediates cap-dependent translation by way of mTOR signaling. Immortalized Chinese hamster ovary (CHO) control cells (pMV7) and CHO cells with forced eIF4E-overexpression (rb4E) were used to elucidate the role of eIF4E in telomerase regulation by perillyl alcohol and rapamycin. Telomerase activity and TERT protein levels were dramatically attenuated in rb4E cells by perillyl alcohol or rapamycin, but the pMV7 cells were unresponsive to either agent. Through western blot analysis we determined eIF4E-overexpression activates Akt–an upstream regulator of mTOR–through a positive-feedback loop thereby increasing the phosphorylation of downstream targets of Akt. These findings demonstrate that eIF4E-overexpression in CHO cells alters protein synthetic processes and gene regulation, thus enabling the inhibitory effects of perillyl alcohol and rapamycin on telomerase activity and TERT protein levels. This study provides evidence for a unique link between perillyl alcohol- and rapamycin-mediated regulation of mTOR and hTERT

Therapeutic targeting of replicative immortality

One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed “senescence,” can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cells’ heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy

A novel automated SARS-CoV-2 saliva PCR test protects a global asymptomatic workforce

Abstract Regular PCR testing of nasopharyngeal swabs from symptomatic individuals for SARS-CoV-2 virus has become the established method by which health services are managing the COVID-19 pandemic. Businesses such as AstraZeneca have also prioritised voluntary asymptomatic testing to keep workplaces safe and maintain supply of essential medicines to patients. We describe the development of an internal automated SARS-CoV-2 testing programme including the transformative introduction of saliva as an alternative sample type

Designing a broad-spectrum integrative approach for cancer prevention and treatment.

Targeted therapies and the consequent adoption of "personalized" oncology have achieved notable successes in some cancers; however, significant problems remain with this approach. Many targeted therapies are highly toxic, costs are extremely high, and most patients experience relapse after a few disease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistant immortalized cells that have adopted alternate and compensatory pathways (i.e., pathways that are not reliant upon the same mechanisms as those which have been targeted). To address these limitations, an international task force of 180 scientists was assembled to explore the concept of a low-toxicity "broad-spectrum" therapeutic approach that could simultaneously target many key pathways and mechanisms. Using cancer hallmark phenotypes and the tumor microenvironment to account for the various aspects of relevant cancer biology, interdisciplinary teams reviewed each hallmark area and nominated a wide range of high-priority targets (74 in total) that could be modified to improve patient outcomes. For these targets, corresponding low-toxicity therapeutic approaches were then suggested, many of which were phytochemicals. Proposed actions on each target and all of the approaches were further reviewed for known effects on other hallmark areas and the tumor microenvironment. Potential contrary or procarcinogenic effects were found for 3.9% of the relationships between targets and hallmarks, and mixed evidence of complementary and contrary relationships was found for 7.1%. Approximately 67% of the relationships revealed potentially complementary effects, and the remainder had no known relationship. Among the approaches, 1.1% had contrary, 2.8% had mixed and 62.1% had complementary relationships. These results suggest that a broad-spectrum approach should be feasible from a safety standpoint. This novel approach has potential to be relatively inexpensive, it should help us address stages and types of cancer that lack conventional treatment, and it may reduce relapse risks. A proposed agenda for future research is offered.Multiple funders. See acknowledgments within article for details.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.semcancer.2015.09.00