Emerging Role of Garcinol in Targeting Cancer Stem Cells of Non-small Cell Lung Cancer

Cancer Stem Cell (CSC) Inhibitors in Oncology-A Promise for a Better Therapeutic Outcome: State of the Art and Future Perspectives

Cancer stem cells (CSCs), a subpopulation of cancer cells endowed with self-renewal, tumorigenicity, pluripotency, chemoresistance, differentiation, invasive ability, and plasticity, reside in specialized tumor niches and are responsible for tumor maintenance, metastasis, therapy resistance, and tumor relapse. The new-age "hierarchical or CSC" model of tumor heterogeneity is based on the concept of eradicating CSCs to prevent tumor relapse and therapy resistance. Small-molecular entities and biologics acting on various stemness signaling pathways, surface markers, efflux transporters, or components of complex tumor microenvironment are under intense investigation as potential anti-CSC agents. In addition, smart nanotherapeutic tools have proved their utility in achieving CSC targeting. Several CSC inhibitors in clinical development have shown promise, either as mono- or combination therapy, in refractory and difficult-to-treat cancers. Clinical investigations with CSC marker follow-up as a measure of clinical efficacy are needed to turn the "hype" into the "hope" these new-age oncology therapeutics have to offer.

Dietary molecules and experimental evidence of epigenetic influence in cancer chemoprevention: An insight

The world-wide rate of incidence of cancer disease has been only modestly contested by the past and current preventive and interventional strategies. Hence, the global effort towards novel ideas to contain the disease still continues. Constituents of human diets have in recent years emerged as key regulators of carcinogenesis, with studies reporting their inhibitory potential against all the three stages vis-a-vis initiation, promotion and progression. Unlike drugs which usually act on single targets, these dietary factors have an advantage of multi-targeted effects and pleiotropic action mechanisms, which are effective against cancer that manifest as a micro-evolutionary and multi-factorial disease. Since most of the cellular targets have been identified and their consumption considered relatively safe, these diet-derived agents often appear as molecules of interest in repurposing strategies. Currently, many of these molecules are being investigated for their ability to influence the aberrant alterations in cell's epigenome for epigenetic therapy against cancer. Targeting the epigenetic regulators is a new paradigm in cancer chemoprevention which acts to reverse the warped-up epigenetic alterations in a cancer cell, thereby directing it towards a normal phenotype. In this review, we discuss the significance of dietary factors and natural products as chemopreventive agents. Further, we corroborate the experimental evidence from existing literature, reflecting the ability of a series of such molecules to act as epigenetic modifiers in cancer cells, by interfering with molecular events that map the epigenetic imprints such as DNA methylation, histone acetylation and non-coding RNA mediated gene regulation.

Garcinol Exhibits Anti-Neoplastic Effects by Targeting Diverse Oncogenic Factors in Tumor Cells

Garcinol, a polyisoprenylated benzophenone, is the medicinal component obtained from fruits and leaves of Garcinia indica (G. indica) and has traditionally been extensively used for its antioxidant and anti-inflammatory properties. In addition, it has been also been experimentally illustrated to elicit anti-cancer properties. Several in vitro and in vivo studies have illustrated the potential therapeutic efficiency of garcinol in management of different malignancies. It mainly acts as an inhibitor of cellular processes via regulation of transcription factors NF-κB and JAK/STAT3 in tumor cells and have been demonstrated to effectively inhibit growth of malignant cell population. Numerous studies have highlighted the anti-neoplastic potential of garcinol in different oncological transformations including colon cancer, breast cancer, prostate cancer, head and neck cancer, hepatocellular carcinoma, etc. However, use of garcinol is still in its pre-clinical stage and this is mainly attributed to the limitations of conclusive evaluation of pharmacological parameters. This necessitates evaluation of garcinol pharmacokinetics to precisely identify an appropriate dose and route of administration, tolerability, and potency under physiological conditions along with characterization of a therapeutic index. Hence, the research is presently ongoing in the dimension of exploring the precise metabolic mechanism of garcinol. Despite various lacunae, garcinol has presented with promising anti-cancer effects. Hence, this review is motivated by the constantly emerging and promising positive anti-cancerous effects of garcinol. This review is the first effort to summarize the mechanism of action of garcinol in modulation of anti-cancer effect via regulation of different cellular processes.

Dietary Garcinol Attenuates Hepatic Pyruvate and Triglyceride Accumulation by Inhibiting P300/CBP-Associated Factor in Mid-to-Late Pregnant Rats

BACKGROUND

Increased hepatic glycolysis and lipogenesis are characteristic of pregnancy.

OBJECTIVES

The present study aimed to investigate the mechanism of garcinol on the amelioration of hepatic pyruvate and triglyceride (TG) accumulation in mid-to-late pregnant rats.

METHODS

Forty Sprague-Dawley pregnant rats (aged 9 wk, n = 10/diet) were fed a basal diet (control) or that diet plus garcinol at 100 ppm (Low Gar), 300 ppm (Mid Gar), or 500 ppm (High Gar) for 14 d. The livers were processed for Western blotting analyses and measuring enzymatic activity and pyruvate and TG concentrations. Hepatocytes from other pregnant Sprague Dawley rats were transfected with P300/CBP associating factor (PCAF) short interfering (si)RNAs; hepatocytes from nonpregnant Sprague-Dawley rats with overexpression of PCAF were treated with garcinol (5 μM). The activity and acetylation of upstream stimulatory factor (USF-1) and glycolytic enzymes were analyzed.

RESULTS

Dietary garcinol significantly decreased (P < 0.05) concentrations of hepatic and plasma TG (27.1-45.8%) and total cholesterol (25.3-49.5%), plasma free fatty acids (24.4-37.8%), and hepatic pyruvate (31.5-43.5%) and lactate (33.4-65.7%) in mid-to-late pregnant rats. Garcinol promoted (P < 0.05) antioxidant capacity in the liver and plasma by 27.4-32.1%. Garcinol downregulated (P < 0.05) lipid synthesis-related enzyme expression by 30.6-85.3% and decreased (P < 0.05) glycolytic enzyme activities by 22.5-74.6% and PCAF activity by 18.6-55.4%. Transfection of PCAF siRNAs to hepatocytes of pregnant rats decreased USF-1 and glycolytic enzyme activities by PCAF; garcinol treatment downregulated (P < 0.05) the acetylation and activities of USF-1 and glycolytic enzymes by 35.6-83.7%.

CONCLUSIONS

Garcinol attenuates hepatic pyruvate and TG accumulation in the liver of mid-to-late pregnant rats, which may be due to downregulating the acetylation of USF-1 and the glycolytic enzymes induced by PCAF in isolated hepatocytes.