Coupling to a cancer cell-specific antibody potentiates tumoricidal properties of curcumin

Polyphenols: Chemoprevention and therapeutic potentials in hematological malignancies

Polyphenols are one of the largest plant-derived natural product and they play an important role in plants' defense as well as in human health and disease. A number of them are pleiotropic molecules and have been shown to regulate signaling pathways, immune response and cell growth and proliferation which all play a role in cancer development. Hematological malignancies on the other hand, are cancers of the blood. While current therapies are efficacious, they are usually expensive and with unwanted side effects. Thus, the search for newer less toxic agents. Polyphenols have been reported to possess antineoplastic properties which include cell cycle arrest, and apoptosis via multiple mechanisms. They also have immunomodulatory activities where they enhance T cell activation and suppress regulatory T cells. They carry out these actions through such pathways as PI3K/Akt/mTOR and the kynurenine. They can also reverse cancer resistance to chemotherapy agents. In this review, i look at some of the molecular mechanism of action of polyphenols and their potential roles as therapeutic agents in hematological malignancies. Here i discuss their anti-proliferative and anti-neoplastic activities especially their abilities modulate signaling pathways as well as immune response in hematological malignancies. I also looked at clinical studies done mainly in the last 10-15 years on various polyphenol combination and how they enhance synergism. I recommend that further preclinical and clinical studies be carried out to ensure safety and efficacy before polyphenol therapies be officially moved to the clinics.

Curcumin as an Adjuvant to Cancer Immunotherapy

The components of the immune system play a very sincere and crucial role in combating tumors. However, despite their firm efforts of elimination, tumor cells cleverly escape the surveillance process by adopting several immune evasion mechanisms. The conversion of immunogenicity of tumor microenvironment into tolerogenic is considered as a prime reason for tumor immune escape. Therapeutically, different immunotherapies have been adopted to block such immune escaping routes along with better clinical outcomes. Still, the therapies are haunted by several drawbacks. Over time, curcumin has been considered as a potential anti-cancer molecule. Its potentialities have been recorded against the standard hallmarks of cancer such as continuous proliferation, escaping apoptosis, continuous angiogenesis, insensitivity to growth inhibitors, tissue invasion, and metastasis. Hence, the diversity of curcumin functioning has already been established and exploration of its application with immunotherapies might open up a new avenue for scientists and clinicians. In this review, we briefly discuss the tumor's way of immune escaping, followed by various modern immunotherapies that have been used to encounter the escaping paths and their minute flaws. Finally, the conclusion has been drawn with the application of curcumin as a potential immune-adjuvant, which fearlessly could be used with immunotherapies for best outcomes.

NF-κB in Cancer Immunity: Friend or Foe?

The emergence of immunotherapies has definitely proven the tight relationship between malignant and immune cells, its impact on cancer outcome and its therapeutic potential. In this context, it is undoubtedly critical to decipher the transcriptional regulation of these complex interactions. Following early observations demonstrating the roles of NF-κB in cancer initiation and progression, a series of studies converge to establish NF-κB as a master regulator of immune responses to cancer. Importantly, NF-κB is a family of transcriptional activators and repressors that can act at different stages of cancer immunity. In this review, we provide an overview of the selective cell-intrinsic contributions of NF-κB to the distinct cell types that compose the tumor immune environment. We also propose a new view of NF-κB targeting drugs as a new class of immunotherapies for cancer.

Unraveling the molecular mechanisms and the potential chemopreventive/therapeutic properties of natural compounds in melanoma

Melanoma is the most fatal form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, targeted therapy and immunotherapy. However, these treatment strategies are associated with development of drug resistance and severe side effects. In recent years, natural compounds have also been extensively studied for their anti-melanoma effects, including tumor growth inhibition, apoptosis induction, angiogenesis and metastasis suppression and cancer stem cell elimination. Moreover, a considerable number of studies reported the synergistic activity of phytochemicals and standard anti-melanoma agents, as well as the enhanced effectiveness of their synthetic derivatives and novel formulations. However, clinical data confirming these promising effects in patients are still scanty. This review emphasizes the anti-tumor mechanisms and potential application of the most studied natural products for melanoma prevention and treatment.

Phytosomal curcumin causes natural killer cell-dependent repolarization of glioblastoma (GBM) tumor-associated microglia/macrophages and elimination of GBM and GBM stem cells

BACKGROUND

Glioblastoma (GBM) is a primary brain tumor with a 5-year survival rate of ≤5%. We have shown earlier that GBM-antibody-linked curcumin (CC) and also phytosomal curcumin (CCP) rescue 50-60% of GBM-bearing mice while repolarizing the tumor-associated microglia/macrophages (TAM) from the tumor-promoting M2-type to the tumoricidal M1-type. However, systemic application of CCP yields only sub-IC50 concentrations of CC in the plasma, which is unlikely to kill GBM cells directly. This study investigates the role of CC-evoked intra-GBM recruitment of activated natural killer (NK) cells in the elimination of GBM and GBM stem cells.

METHODS

We have used an immune-competent syngeneic C57BL6 mouse model with the mouse-GBM GL261 cells orthotopically implanted in the brain. Using immunohistochemistry and flow cytometry, we have quantitatively analyzed the role of the intra-GBM-recruited NK cells by (i) injecting (i.p.) the NK1.1 antibody (NK1.1Ab) to temporarily eliminate the NK cells and (ii) blocking NK recruitment by injecting an IL12 antibody (IL12Ab). The treatment cohorts used randomly-chosen GL261-implanted mice and data sets were compared using two-tailed t-test or ANOVA.

RESULTS

CCP treatment caused the GBM tumor to acquire M1-type macrophages (50-60% of the TAM) and activated NK cells. The treatment also elicited (a) suppression of the M2-linked tumor-promoting proteins STAT3, ARG1, and IL10, (b) induction of the M1-linked anti-tumor proteins STAT1 and inducible nitric oxide synthase in the TAM, (c) elimination of CD133(+) GBM stem cells, and (d) activation of caspase3 in the GBM cells. Eliminating intra-GBM NK cell recruitment caused a partial reversal of each of these effects. Concomitantly, we observed a CCP-evoked dramatic induction of the chemokine monocyte chemotactic protein-1 (MCP-1) in the TAM.

CONCLUSIONS

The recruited NK cells mediate a major part of the CCP-evoked elimination of GBM and GBM stem cells and stabilization of the TAM in the M1-like state. MCP-1 is known to activate peripheral M1-type macrophages to secrete IL12, an activator of NK cells. Based on such observations, we postulate that by binding to peripheral M1-type macrophages and IL12-activated NK cells, the brain-released chemokine MCP-1 causes recruitment of peripheral immune cells into the GBM, thereby causing destruction of the GBM cells and GBM stem cells.

TriCurin, a synergistic formulation of curcumin, resveratrol, and epicatechin gallate, repolarizes tumor-associated macrophages and triggers an immune response to cause suppression of HPV+ tumors

Our earlier studies reported a unique potentiated combination (TriCurin) of curcumin (C) with two other polyphenols. The TriCurin-associated C displays an IC50 in the low micromolar range for cultured HPV+ TC-1 cells. In contrast, because of rapid degradation in vivo, the TriCurin-associated C reaches only low nano-molar concentrations in the plasma, which are sub-lethal to tumor cells. Yet, injected TriCurin causes a dramatic suppression of tumors in TC-1 cell-implanted mice (TC-1 mice) and xenografts of Head and Neck Squamous Cell Carcinoma (HNSCC) cells in nude/nude mice. Here, we use the TC-1 mice to test our hypothesis that a major part of the anti-tumor activity of TriCurin is evoked by innate and adaptive immune responses. TriCurin injection repolarized arginase1high (ARG1high), IL10high, inducible nitric oxide synthaselow (iNOSlow), IL12low M2-type tumor-associated macrophages (TAM) into ARG1low, IL10low, iNOShigh, and IL12high M1-type TAM in HPV+ tumors. The M1 TAM displayed sharply suppressed STAT3 and induced STAT1 and NF-kB(p65). STAT1 and NF-kB(p65) function synergistically to induce iNOS and IL12 transcription. Neutralizing IL12 signaling with an IL12 antibody abrogated TriCurin-induced intra-tumor entry of activated natural killer (NK) cells and Cytotoxic T lymphocytes (CTL), thereby confirming that IL12 triggers recruitment of NK cells and CTL. These activated NK cells and CTL join the M1 TAM to elicit apoptosis of the E6+ tumor cells. Corroboratively, neutralizing IL12 signaling partially reversed this TriCurin-mediated apoptosis. Thus, injected TriCurin elicits an M2→M1 switch in TAM, accompanied by IL12-dependent intra-tumor recruitment of NK cells and CTL and elimination of cancer cells.

Liposomal TriCurin, A Synergistic Combination of Curcumin, Epicatechin Gallate and Resveratrol, Repolarizes Tumor-Associated Microglia/Macrophages, and Eliminates Glioblastoma (GBM) and GBM Stem Cells

Glioblastoma (GBM) is a deadly brain tumor with a current mean survival of 12-15 months. Despite being a potent anti-cancer agent, the turmeric ingredient curcumin (C) has limited anti-tumor efficacy in vivo due to its low bioavailability. We have reported earlier a strategy involving the use two other polyphenols, epicatechin gallate (E) from green tea and resveratrol (R) from red grapes at a unique, synergistic molar ratio with C (C:E:R: 4:1:12.5, termed TriCurin) to achieve superior potency against HPV+ tumors than C alone at C:E:R (μM): 32:8:100 (termed 32 μM+ TriCurin). We have now prepared liposomal TriCurin (TrLp) and demonstrated that TrLp boosts activated p53 in cultured GL261 mouse GBM cells to trigger apoptosis of GBM and GBM stem cells in vitro. TrLp administration into mice yielded a stable plasma concentration of 210 nM C for 60 min, which, though sub-lethal for cultured GL261 cells, was able to cause repolarization of M2-like tumor (GBM)-associated microglia/macrophages to the tumoricidal M1-like phenotype and intra-GBM recruitment of activated natural killer cells. The intratumor presence of such tumoricidal immune cells was associated with concomitant suppression of tumor-load, and apoptosis of GBM and GBM stem cells. Thus, TrLp is a potential onco-immunotherapeutic agent against GBM tumors.

Unique synergistic formulation of curcumin, epicatechin gallate and resveratrol, tricurin, suppresses HPV E6, eliminates HPV+ cancer cells, and inhibits tumor progression

Curcumin (from curry) (C) is highly potent against cervical cancer cells (CCC), but poor bioavailability has limited its clinical use. Similar natural polyphenols resveratrol (from grapes) (R), and epicatechin gallate (from green tea) (E) also display activity against CCC. By treating CCC (HeLa) with C, E, or R, or combinations of these compounds, we computed combination indices and observed a strong synergism among C, E, and R at the unique molar ratio 4:1:12.5. This combination, named as TriCurin, rapidly down regulated HPV18 E6 and NF-kB expression while concomitantly inducing the tumor suppressor protein p53 in HeLa cells. In the mouse c-Ha-ras and HPV16 E6, E7-expressing TC-1 CCC, both C and TriCurin elicited suppression of E6, induction of both p53 and acetyl-p53 (activated p53), and activation of caspase-3, but the TriCurin-evoked changes were several-fold greater than that produced by curcumin (4.7-fold for E6 inhibition, and 2-fold, 6-fold, and 1.7-fold for the induction of p53, acetyl-p53, and active caspase-3, respectively). Consequently, TriCurin was more potent in killing TC-1 and HeLa cells. Intralesional TriCurin treatment of tumors generated in mice by subcutaneously implanting the TC-1 CCC caused an 80–90% decrease in tumor growth. The ability of C to eliminate HeLa cells was significantly stabilized when delivered as TriCurin than when delivered alone. Topical application of TriCurin dispersed in a cream base afforded efficient transfer of C across the skin. Subcutaneous TriCurin injection yielded no adverse effect in tumor-naïve healthy mice. Thus, TriCurin is a safe and promising therapeutic agent against HPV-associated disease.

Therapeutic Potential of Curcumin for the Treatment of Brain Tumors

Brain malignancies currently carry a poor prognosis despite the current multimodal standard of care that includes surgical resection and adjuvant chemotherapy and radiation. As new therapies are desperately needed, naturally occurring chemical compounds have been studied for their potential chemotherapeutic benefits and low toxicity profile. Curcumin, found in the rhizome of turmeric, has extensive therapeutic promise via its antioxidant, anti-inflammatory, and antiproliferative properties. Preclinical in vitro and in vivo data have shown it to be an effective treatment for brain tumors including glioblastoma multiforme. These effects are potentiated by curcumin's ability to induce G2/M cell cycle arrest, activation of apoptotic pathways, induction of autophagy, disruption of molecular signaling, inhibition of invasion, and metastasis and by increasing the efficacy of existing chemotherapeutics. Further, clinical data suggest that it has low toxicity in humans even at large doses. Curcumin is a promising nutraceutical compound that should be evaluated in clinical trials for the treatment of human brain tumors.

Curcumin: A new candidate for melanoma therapy?

Melanoma remains among the most lethal cancers and, in spite of great attempts that have been made to increase the life span of patients with metastatic disease, durable and complete remissions are rare. Plants and plant extracts have long been used to treat a variety of human conditions; however, in many cases, effective doses of herbal remedies are associated with serious adverse effects. Curcumin is a natural polyphenol that shows a variety of pharmacological activities including anti-cancer effects, and only minimal adverse effects have been reported for this phytochemical. The anti-cancer effects of curcumin are the result of its anti-angiogenic, pro-apoptotic and immunomodulatory properties. At the molecular and cellular level, curcumin can blunt epithelial-to-mesenchymal transition and affect many targets that are involved in melanoma initiation and progression (e.g., BCl2, MAPKS, p21 and some microRNAs). However, curcumin has a low oral bioavailability that may limit its maximal benefits. The emergence of tailored formulations of curcumin and new delivery systems such as nanoparticles, liposomes, micelles and phospholipid complexes has led to the enhancement of curcumin bioavailability. Although in vitro and in vivo studies have demonstrated that curcumin and its analogues can be used as novel therapeutic agents in melanoma, curcumin has not yet been tested against melanoma in clinical practice. In this review, we summarized reported anti-melanoma effects of curcumin as well as studies on new curcumin formulations and delivery systems that show increased bioavailability. Such tailored delivery systems could pave the way for enhancement of the anti-melanoma effects of curcumin.

Coupling to a glioblastoma-directed antibody potentiates antitumor activity of curcumin

Current therapies for glioblastoma are largely palliative, involving surgical resection followed by chemotherapy and radiation therapy, which yield serious side effects and very rarely produce complete recovery. Curcumin, a food component, blocked brain tumor formation but failed to eliminate established brain tumors in vivo, probably because of its poor bioavailability. In the glioblastoma GL261 cells, it suppressed the tumor-promoting proteins NF-κB, P-Akt1, vascular endothelial growth factor, cyclin D1 and BClXL and triggered cell death. Expression of exogenous p50 and p65 subunits of NF-κB conferred partial protection on transfected GL261 cells against curcumin insult, indicating that NF-κB played a key role in protecting glioblastoma cells. To enhance delivery, we coupled curcumin to the glioblastoma-specific CD68 antibody in a releasable form. This resulted in a 120-fold increase in its efficacy to eliminate GL261 cells. A very similar dose response was also obtained with human glioblastoma lines T98G and U87MG. GL261-implanted mice receiving intratumor infusions of the curcumin-CD68 adduct followed by tail-vein injections of solubilized curcumin displayed a fourfold to fivefold reduction in brain tumor load, survived longer, and about 10% of them lived beyond 100 days. Hematoxylin-eosin staining of brain sections revealed a small scar tissue mass in the rescued mice, indicating adduct-mediated elimination of glioblastoma tumor. The tumor cells were strongly CD68+ and some cells in the tumor periphery were strongly positive for microglial Iba1, but weakly positive for CD68. This strategy of antibody targeting of curcumin to tumor comes with the promise of yielding a highly effective therapy for glioblastoma brain tumors.

A novel curcumin-based vaginal cream Vacurin selectively eliminates apposed human cervical cancer cells

OBJECTIVE

Human papillomavirus (HPV) infections remain a leading cause of mortality worldwide. In the U.S. strategies via screening and vaccination prevent HPV-associated cervical neoplasms, but consume immense healthcare costs. The spice component curcumin has potent anticancer and antiviral properties, which have been difficult to harness as a treatment, due to its poor systemic bioavailability. This project tests the possibility of developing a curcumin-based therapy for cervical cancer.

METHODS

Using four HPV(+) cervical cancer cell lines and normal fibroblasts we first tested the selectivity and potency of curcumin in eliminating HPV(+) cells. Subsequently, we developed a curcumin-based cervical cream and tested its efficacy in eliminating apposed HPV(+) cells and also its possible side effects on the vaginal epithelium of healthy mice.

RESULTS

Curcumin selectively eliminates a variety of HPV(+) cervical cancer cells (HeLa, ME-180, SiHa, and SW756), suppresses the transforming antigen E6, dramatically inhibits the expression of the pro-cancer protein epidermal growth factor receptor (EGFR), and concomitantly induces p53. Additionally, Vacurin, a uniform colloidal solution of curcumin in a clinically used amphipathic vaginal cream, eliminates apposed HeLa cells while suppressing the expression of EGFR. In mice, daily intravaginal application of Vacurin for three weeks produced no change in body weight and when the mice were sacrificed, the vaginal tract epithelium showed no Vacurin-evoked adverse effects.

CONCLUSION

We have developed a curcumin-based vaginal cream, which effectively eradicates HPV(+) cancer cells and does not affect non-cancerous tissue. Our preclinical data support a novel approach for the treatment of cervical HPV infection.

Chemoprevention of melanoma

Despite advances in drug discovery programs and molecular approaches for identifying drug targets, incidence and mortality rates due to melanoma continue to rise at an alarming rate. Existing preventive strategies generally involve mole screening followed by surgical removal of the benign nevi and abnormal moles. However, due to lack of effective programs for screening and disease recurrence after surgical resection, there is a need for better chemopreventive agents. Although sunscreens have been used extensively for protecting from UV-induced melanomas, results of correlative population-based studies are controversial, with certain studies suggest increased skin cancer risk in sunscreen users. Therefore, these studies require further authentication to conclusively confirm the chemoprotective efficacy of sunscreens. This chapter reviews the current understanding regarding melanoma chemoprevention and the various strategies used to accomplish this objective.