rWTC-MBTA Vaccine Induces Potent Adaptive Immune Responses Against Glioblastomas via Dynamic Activation of Dendritic Cells.

Despite strides in immunotherapy, glioblastoma multiforme (GBM) remains challenging due to low inherent immunogenicity and suppressive tumor microenvironment. Converting "cold" GBMs to "hot" is crucial for immune activation and improved outcomes. This study comprehensively characterized a therapeutic vaccination strategy for preclinical GBM models. The vaccine consists of Mannan-BAM-anchored irradiated whole tumor cells, Toll-like receptor ligands [lipoteichoic acid (LTA), polyinosinic-polycytidylic acid (Poly (I:C)), and resiquimod (R-848)], and anti-CD40 agonistic antibody (rWTC-MBTA). Intracranial GBM models (GL261, SB28 cells) are used to evaluate the vaccine efficacy. A substantial number of vaccinated mice exhibited complete regression of GBM tumors in a T-cell-dependent manner, with no significant toxicity. Long-term tumor-specific immune memory is confirmed upon tumor rechallenge. In the vaccine-draining lymph nodes of the SB28 model, rWTC-MBTA vaccination triggered a major rise in conventional dendritic cell type 1 (cDC1) 12 h post-treatment, followed by an increase in conventional dendritic cell type 2 (cDC2), monocyte-derived dendritic cell (moDC), and plasmacytoid dendritic cell (pDC) on Day 5 and Day 13. Enhanced cytotoxicity of CD4+ and CD8+ T cells in vaccinated mice is verified in co-culture with tumor cells. Analyses of immunosuppressive signals (T-cell exhaustion, myeloid-derived suppressor cells (MDSC), M2 macrophages) in the GBM microenvironment suggest potential combinations with other immunotherapies for enhanced efficacy. In conclusion, the authors findings demonstrate that rWTC-MBTA induces potent and long-term adaptive immune responses against GBM.

Application of toll-like receptors (TLRs) and their agonists in cancer vaccines and immunotherapy.

Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) expressed in various immune cell types and perform multiple purposes and duties involved in the induction of innate and adaptive immunity. Their capability to propagate immunity makes them attractive targets for the expansion of numerous immunotherapeutic approaches targeting cancer. These immunotherapeutic strategies include using TLR ligands/agonists as monotherapy or combined therapeutic strategies. Several TLR agonists have demonstrated significant efficacy in advanced clinical trials. In recent years, multiple reports established the applicability of TLR agonists as adjuvants to chemotherapeutic drugs, radiation, and immunotherapies, including cancer vaccines. Cancer vaccines are a relatively novel approach in the field of cancer immunotherapy and are currently under extensive evaluation for treating different cancers. In the present review, we tried to deliver an inclusive discussion of the significant TLR agonists and discussed their application and challenges to their incorporation into cancer immunotherapy approaches, particularly highlighting the usage of TLR agonists as functional adjuvants to cancer vaccines. Finally, we present the translational potential of rWTC-MBTA vaccination [irradiated whole tumor cells (rWTC) pulsed with phagocytic agonists Mannan-BAM, TLR ligands, and anti-CD40 agonisticAntibody], an autologous cancer vaccine leveraging membrane-bound Mannan-BAM, and the immune-inducing prowess of TLR agonists as a probable immunotherapy in multiple cancer types.

rWTC-MBTA: autologous vaccine prevents metastases via antitumor immune responses.

BACKGROUND: Autologous tumor cell-based vaccines (ATVs) aim to prevent and treat tumor metastasis by activating patient-specific tumor antigens to induce immune memory. However, their clinical efficacy is limited. Mannan-BAM (MB), a pathogen-associated molecular pattern (PAMP), can coordinate an innate immune response that recognizes and eliminates mannan-BAM-labeled tumor cells. TLR agonists and anti-CD40 antibodies (TA) can enhance the immune response by activating antigen-presenting cells (APCs) to present tumor antigens to the adaptive immune system. In this study, we investigated the efficacy and mechanism of action of rWTC-MBTA, an autologous whole tumor cell vaccine consisting of irradiated tumor cells (rWTC) pulsed with mannan-BAM, TLR agonists, and anti-CD40 antibody (MBTA), in preventing tumor metastasis in multiple animal models. METHODS: The efficacy of the rWTC-MBTA vaccine was evaluated in mice using breast (4T1) and melanoma (B16-F10) tumor models via subcutaneous and intravenous injection of tumor cells to induce metastasis. The vaccine's effect was also assessed in a postoperative breast tumor model (4T1) and tested in autologous and allogeneic syngeneic breast tumor models (4T1 and EMT6). Mechanistic investigations included immunohistochemistry, immunophenotyping analysis, ELISA, tumor-specific cytotoxicity testing, and T-cell depletion experiments. Biochemistry testing and histopathology of major tissues in vaccinated mice were also evaluated for potential systemic toxicity of the vaccine. RESULTS: The rWTC-MBTA vaccine effectively prevented metastasis and inhibited tumor growth in breast tumor and melanoma metastatic animal models. It also prevented tumor metastasis and prolonged survival in the postoperative breast tumor animal model. Cross-vaccination experiments revealed that the rWTC-MBTA vaccine prevented autologous tumor growth, but not allogeneic tumor growth. Mechanistic data demonstrated that the vaccine increased the percentage of antigen-presenting cells, induced effector and central memory cells, and enhanced CD4+ and CD8+ T-cell responses. T-cells obtained from mice that were vaccinated displayed tumor-specific cytotoxicity, as shown by enhanced tumor cell killing in co-culture experiments, accompanied by increased levels of Granzyme B, TNF-α, IFN-γ, and CD107a in T-cells. T-cell depletion experiments showed that the vaccine's antitumor efficacy depended on T-cells, especially CD4+ T-cells. Biochemistry testing and histopathology of major tissues in vaccinated mice revealed negligible systemic toxicity of the vaccine. CONCLUSION: The rWTC-MBTA vaccine demonstrated efficacy in multiple animal models through T-cell mediated cytotoxicity and has potential as a therapeutic option for preventing and treating tumor metastasis with minimal systemic toxicity.

Impact of smoking-induced dysregulated human miRNAs in chronic disease development and their potential use in prognostic and therapeutic purposes.

MicroRNAs (miRNAs) are evolutionary conserved small noncoding RNA molecules with a significant ability to regulate gene expression at the posttranscriptional level either through translation repression or messenger RNA degradation. miRNAs are differentially expressed in various pathophysiological conditions, affecting the course of the disease by modulating several critical target genes. As the persistence of irreversible molecular changes caused by cigarette smoking is central to the pathogenesis of various chronic diseases, several studies have shown its direct correlation with the dysregulation of different miRNAs, affecting numerous essential biological processes. This review provides an insight into the current status of smoking-induced miRNAs dysregulation in chronic diseases such as COPD, atherosclerosis, pulmonary hypertension, and different cancers and explores the diagnostic/prognostic potential of miRNA-based biomarkers and their efficacy as therapeutic targets.

A Brief Review on the Regulatory Roles of MicroRNAs in Cystic Diseases and Their Use as Potential Biomarkers.

miRNAs are small endogenous conserved non-coding RNA molecules that regulate post-transcriptional gene expression through mRNA degradation or translational inhibition, modulating nearly 60% of human genes. Cystic diseases are characterized by the presence of abnormal fluid-filled sacs in the body, and though most cysts are benign, they can grow inside tumors and turn malignant. Recent evidence has revealed that the aberrant expression of a number of miRNAs present in extracellular fluids, including plasma or serum, urine, saliva, follicular fluid, and semen, contribute to different cystic pathologies. This review aims to describe the role of different miRNAs in three worldwide relevant cystic diseases: polycystic ovarian syndrome (PCOS), polycystic kidney disease (PKD), and pancreatic cyst tumors (PCTs), as well as their potential use as novel biomarkers.

Engineered titania nanomaterials in advanced clinical applications.

Significant advancement in the field of nanotechnology has raised the possibility of applying potent engineered biocompatible nanomaterials within biological systems for theranostic purposes. Titanium dioxide (titanium(IV) oxide/titania/TiO2) has garnered considerable attention as one of the most extensively studied metal oxides in clinical applications. Owing to the unique properties of titania, such as photocatalytic activity, excellent biocompatibility, corrosion resistance, and low toxicity, titania nanomaterials have revolutionized therapeutic approaches. Additionally, titania provides an exceptional choice for developing innovative medical devices and the integration of functional moieties that can modulate the biological responses. Thus, the current review aims to present a comprehensive and up-to-date overview of TiO2-based nanotherapeutics and the corresponding future challenges.

A Combination therapy using an mTOR inhibitor and Honokiol effectively induces autophagy through the modulation of AXL and Rubicon in renal cancer cells and restricts renal tumor growth following organ transplantation.

Development of cancer, including renal cancer, is a major problem in immunosuppressed patients. The mTOR inhibitor Rapamycin (RAPA) is used as an immunosuppressive agent in patients with organ transplants and other immunological disorders; and it also has antitumorigenic potential. However, long-term use of RAPA causes reactivation of Akt, and ultimately leads to enhanced tumor growth. Honokiol (HNK) is a natural compound, which possesses both anti-inflammatory and antitumorigenic properties. In this study, we investigated the effect of a novel combination therapy using RAPA + HNK on allograft survival and post-transplantation renal tumor growth. We observed that it effectively modulated the expression of some key regulatory molecules (like Carabin, an endogenous Ras inhibitor; and Rubicon, a negative regulator of autophagy) that play important roles in tumor cell growth and survival. This combination induced toxic autophagy and apoptosis to promote cancer cell death; and was associated with a reduced expression of the tumor-promoting receptor tyrosine kinase AXL. Finally, we utilized a novel murine model to examine the effect of RAPA + HNK on post-transplantation renal tumor growth. The combination treatment prolonged the allograft survival and significantly inhibited post-transplantation tumor growth. It was associated with reduced tumor expression of Rubicon and the cytoprotective/antioxidant heme oxygenase-1 to overcome therapeutic resistance. It also downregulated the coinhibitory programmed death-1 ligand, which plays major role(s) in the immune escape of tumor cells. Together, this combination treatment has a great potential to restrict renal tumor growth in transplant recipients as well as other immunosuppressed patients.

The role of microRNAs in solving COVID-19 puzzle from infection to therapeutics: A mini-review.

Nowadays, one of the major global health concerns is coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Even though numerous treatments and vaccines to combat this virus are currently under development, the detailed molecular mechanisms underlying the pathogenesis of this disease are yet to be elucidated to design future therapeutic tools against SARS-CoV-2 variants. MicroRNAs (miRNAs) are small (20-24 nucleotides), non-coding RNA molecules that regulate post-transcriptional gene expression. Recently, it has been demonstrated that both host and viral-encoded miRNAs are crucial for the successful infection of SARS-CoV-2. For instance, dysregulation of miRNAs that modulate multiple genes expressed in COVID-19 patients with comorbidities (e.g., type 2 diabetes, lung adenocarcinoma, and cerebrovascular disorders) could affect the severity of the disease. Thus, altered expression levels of circulating miRNAs might be helpful to diagnose this illness and forecast whether a COVID-19 patient could develop a severe state of the disease. Besides, researchers have found a number of miRNAs could inhibit the expression of proteins, such as ACE2, TMPRSS2, spike, and Nsp12, involved in the life cycle of SARS-CoV-2. Accordingly, miRNAs represent potential biomarkers and therapeutic targets for this devastating viral disease. Therefore, in this current review, we present the recent discoveries regarding the clinical relevance and biological roles of miRNAs in COVID-19.

Phytochemicals mediated modulation of microRNAs and long non-coding RNAs in cancer prevention and therapy.

MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are two main categories of noncoding RNAs (ncRNAs) that can influence essential biological functions in various ways, as well as their expression and function are tightly regulated in physiological homeostasis. Additionally, the dysregulation of these ncRNAs seems to be crucial to the pathogenesis of human diseases. The latest findings indicate that ncRNAs execute vital roles in cancer initiation and progression, and the cancer phenotype can be reversed by modulating their expression. Available scientific discoveries suggest that phytochemicals such as polyphenols, alkaloids, terpenoids, and organosulfur compounds can significantly modulate multiple cancer-associated miRNAs and lncRNAs, thereby inhibiting cancer initiation and development. However, despite promising outcomes of experimental research, only a few clinical trials are currently being conducted to evaluate the therapeutic effectiveness of these compounds. Nevertheless, understanding phytochemical-mediated ncRNA regulation in cancer and the underlying molecular mechanisms on tumor pathophysiology can aid in the development of novel therapeutic strategies to combat this deadly disease.

Roles of microRNAs in carbohydrate and lipid metabolism disorders and their therapeutic potential.

MicroRNAs (miRNAs) are small (∼21 nucleotides), endogenous, non-coding RNA molecules implicated in the post-transcriptional gene regulation performed through target mRNA cleavage or translational inhibition. In recent years, several investigations have demonstrated that miRNAs are involved in regulating both carbohydrate and lipid homeostasis in humans and other organisms. Moreover, it has been observed that the dysregulation of these metabolism-related miRNAs leads to the development of several metabolic disorders, such as type 2 diabetes, obesity, nonalcoholic fatty liver, insulin resistance, and hyperlipidemia. Hence, in this current review, with the aim to impulse the research arena of the micro-transcriptome implications in vital metabolic pathways as well as to highlight the remarkable potential of miRNAs as therapeutic targets for metabolic disorders in humans, we provide an overview of the regulatory roles of metabolism-associated miRNAs in humans and murine models.

Metabolic reprogramming in renal cancer: Events of a metabolic disease.

Recent studies have established that tumors can reprogram the pathways involved in nutrient uptake and metabolism to withstand the altered biosynthetic, bioenergetics and redox requirements of cancer cells. This phenomenon is called metabolic reprogramming, which is promoted by the loss of tumor suppressor genes and activation of oncogenes. Because of alterations and perturbations in multiple metabolic pathways, renal cell carcinoma (RCC) is sometimes termed as a "metabolic disease". The majority of metabolic reprogramming in renal cancer is caused by the inactivation of von Hippel-Lindau (VHL) gene and activation of the Ras-PI3K-AKT-mTOR pathway. Hypoxia-inducible factor (HIF) and Myc are other important players in the metabolic reprogramming of RCC. All types of RCCs are associated with reprogramming of glucose and fatty acid metabolism and the tricarboxylic acid (TCA) cycle. Metabolism of glutamine, tryptophan and arginine is also reprogrammed in renal cancer to favor tumor growth and oncogenesis. Together, understanding these modifications or reprogramming of the metabolic pathways in detail offer ample opportunities for the development of new therapeutic targets and strategies, discovery of biomarkers and identification of effective tumor detection methods.

Current insight into the functions of microRNAs in common human hair loss disorders: a mini review.

Alopecia areata (AA) and Androgenic alopecia (AGA) are the most common multifactorial hair loss disorders that have a serious psychological impact on the affected individuals, while frontal fibrosing alopecia (FFA) is comparatively less common. However, due to the unknown etiology and the effect of many adverse factors, the prognosis of these conditions is challenging to predict. Moreover, no approved therapy has been available to date to prevent or treat these disorders. MicroRNAs (miRNAs) are a group of evolutionary conserved small non-coding RNA molecules with significant roles in the posttranscriptional gene regulation either through mRNA degradation or translational repression. A number of biological processes are controlled by these molecules, including cell growth and differentiation, proliferation, inflammation, immune responses, and apoptosis. Recently, a handful of studies have demonstrated the impact of miRNAs on common hair loss-related disorders; however, the exhaustive molecular mechanisms are still unclear. In this review, we discussed the functional implications of miRNAs in common hair loss-related disorders and addressed their efficacy to be used for theranostic purposes shortly.

The Emerging Role of MicroRNAs in Bone Diseases and Their Therapeutic Potential.

MicroRNAs (miRNAs) are a class of small (20-24 nucleotides), highly conserved, non-coding RNA molecules whose main function is the post-transcriptional regulation of gene expression through sequence-specific manners, such as mRNA degradation or translational repression. Since these key regulatory molecules are implicated in several biological processes, their altered expression affects the preservation of cellular homeostasis and leads to the development of a wide range of pathologies. Over the last few years, relevant investigations have elucidated that miRNAs participate in different stages of bone growth and development. Moreover, the abnormal expression of these RNA molecules in bone cells and tissues has been significantly associated with the progression of numerous bone diseases, including osteoporosis, osteosarcoma, osteonecrosis and bone metastasis, among others. In fact, miRNAs regulate multiple pathological mechanisms, including altering either osteogenic or osteoblast differentiation, metastasis, osteosarcoma cell proliferation, and bone loss. Therefore, in this present review, aiming to impulse the research arena of the biological implications of miRNA transcriptome in bone diseases and to explore their potentiality as a theragnostic target, we summarize the recent findings associated with the clinical significance of miRNAs in these ailments.

Novel Honokiol-eluting PLGA-based scaffold effectively restricts the growth of renal cancer cells.

Renal Cell Carcinoma (RCC) often becomes resistant to targeted therapies, and in addition, dose-dependent toxicities limit the effectiveness of therapeutic agents. Therefore, identifying novel drug delivery approaches to achieve optimal dosing of therapeutic agents can be beneficial in managing toxicities and to attain optimal therapeutic effects. Previously, we have demonstrated that Honokiol, a natural compound with potent anti-tumorigenic and anti-inflammatory effects, can induce cancer cell apoptosis and inhibit the growth of renal tumors in vivo. In cancer treatment, implant-based drug delivery systems can be used for gradual and sustained delivery of therapeutic agents like Honokiol to minimize systemic toxicity. Electrospun polymeric fibrous scaffolds are ideal candidates to be used as drug implants due to their favorable morphological properties such as high surface to volume ratio, flexibility and ease of fabrication. In this study, we fabricated Honokiol-loaded Poly(lactide-co-glycolide) (PLGA) electrospun scaffolds; and evaluated their structural characterization and biological activity. Proton nuclear magnetic resonance data proved the existence of Honokiol in the drug loaded polymeric scaffolds. The release kinetics showed that only 24% of the loaded Honokiol were released in 24hr, suggesting that sustained delivery of Honokiol is feasible. We calculated the cumulative concentration of the Honokiol released from the scaffold in 24hr; and the extent of renal cancer cell apoptosis induced with the released Honokiol is similar to an equivalent concentration of direct application of Honokiol. Also, Honokiol-loaded scaffolds placed directly in renal cell culture inhibited renal cancer cell proliferation and migration. Together, we demonstrate that Honokiol delivered through electrospun PLGA-based scaffolds is effective in inhibiting the growth of renal cancer cells; and our data necessitates further in vivo studies to explore the potential of sustained release of therapeutic agents-loaded electrospun scaffolds in the treatment of RCC and other cancer types.

A Novel Combination Treatment with Honokiol and Rapamycin Effectively Restricts c-Met-Induced Growth of Renal Cancer Cells, and also Inhibits the Expression of Tumor Cell PD-L1 Involved in Immune Escape.

The mTOR inhibitor Rapamycin has tumor inhibitory properties; and it is also used as an immunosuppressive agent after organ transplantation. However, prolonged Rapamycin treatment re-activates Akt and can promote cancer growth. Honokiol is a natural compound with both anti-tumorigenic and anti-inflammatory properties. Here, we assessed the anti-tumor effects of Rapamycin and Honokiol combination in renal cell carcinoma (RCC). Receptor tyrosine kinase c-Met-mediated signaling plays a major role in RCC growth. We observed that compared with Rapamycin alone, Rapamycin + Honokiol combination can effectively down-regulate c-Met-induced Akt phosphorylation in renal cancer cells; and it markedly inhibited Ras activation and cell proliferation and promoted G1 phase cell cycle arrest. The combination treatment significantly induced ROS generation and cancer cell apoptosis even when c-Met is activated. Importantly, Honokiol, but not Rapamycin, decreased c-Met-induced expression of the co-inhibitory molecule PD-L1, implied in the immune escape of renal cancer cells. In mouse renal cancer cells and Balb/c splenocytes co-culture assay, Rapamycin + Honokiol markedly potentiated immune-cell-mediated killing of cancer cells, possibly through the down-regulation of PD-L1. Together, Honokiol can effectively overcome the limitation of Rapamycin treatment alone; and the combination treatment can markedly restrict the growth of RCC, with particular importance to post-transplantation renal cancer.

Signaling Molecules in Posttransplantation Cancer.

Immunosuppression is essential to prevent graft rejection. However, immunosuppression impairs the ability of the host immune system to control viral infection and decreases tumor immunosurveillance. Therefore, immunosuppression after organ transplantation is a major risk factor for posttransplantation cancer. Notably, recent reports suggest that immunosuppressive agents can activate tumorigenic pathways independent of the involvement of the host immune system. In this review, we focus on cell-intrinsic tumorigenic pathways directly activated by immunosuppressive agents and discuss the much-described infection- and immune-mediated mechanisms of cancer development in organ transplant recipients.

Activation of c-Met in cancer cells mediates growth-promoting signals against oxidative stress through Nrf2-HO-1.

Any imbalance between reactive oxygen species (ROS) generation and the anti-oxidant capacity lead to cellular oxidative stress. Many chemotherapeutic agents mediate their cytotoxic functions through the generation of ROS. c-Met, a receptor tyrosine kinase, is over-expressed in renal cancer and plays very crucial role(s) in its growth and survival. Here, we show that c-Met activation protected renal cancer cells from ROS, oxidative stress and cytotoxicity induced by the anti-cancer agent sorafenib (used for renal cancer treatment); and it markedly attenuated sorafenib-induced DNA damage. Activated c-Met promoted the anti-apoptotic proteins (Bcl-2 and Bcl-xL) and inhibited apoptotic cleaved caspase-3. We found that the cytoprotective function of c-Met against sorafenib-induced ROS generation and apoptosis was mediated primarily through the activation of anti-oxidant Nrf2-HO-1. c-Met promoted the nuclear localization of Nrf2 and hindered its binding with the inhibitory protein Keap1. Silencing of Nrf2 attenuated the protective action of c-Met against sorafenib-induced oxidative stress. To evaluate the physiological significance of our findings, in a tumor xenograft model, we observed that a combination treatment with pharmacological inhibitors of c-Met and it's anti-oxidant downstream effecter HO-1 markedly reduced the growth of renal tumor in vivo; it increased the oxidative stress, DNA damage and apoptotic markers in the tumor xenografts, along with reduced tumor vessel density. Our observations indicate that the c-Met-Nrf2-HO-1 pathway plays a vital role in relieving ROS-mediated oxidative stress of renal tumors. Targeting this pathway can significantly increase the oxidative stress to promote apoptotic death of cancer cells.

Honokiol inhibits c-Met-HO-1 tumor-promoting pathway and its cross-talk with calcineurin inhibitor-mediated renal cancer growth.

Honokiol (HNK) is a small molecule with potent anti-inflammatory and anti-tumorigenic properties; yet the molecular targets of HNK are not well studied. Hyperactivation of the receptor tyrosine kinase c-Met and overexpression of the cytoprotective enzyme heme oxygenase-1 (HO-1) play a critical role in the growth and progression of renal cell carcinoma (RCC). Interestingly, the calcineurin inhibitor (CNI) cyclosporine A (CsA), an immunosuppressant used to prevent allograft rejection, can also increase the risk of RCC in transplant patients. We studied the potential role of c-Met signaling axis on CNI-induced renal tumor growth and tested the anti-tumor efficacy of HNK. Importantly, CNI treatment promoted c-Met induction and enhanced c-Met-induced Ras activation. We found that HNK treatment effectively down-regulated both c-Met phosphorylation and Ras activation in renal cancer cells. It inhibited the expression of both c-Met- and CNI-induced HO-1, and promoted cancer cell apoptosis. In vivo, HNK markedly inhibited CNI-induced renal tumor growth; and it decreased the expression of phospho-c-Met and HO-1 and reduced blood vessel density in tumor tissues. Our results suggest a novel mechanism(s) by which HNK exerts its anti-tumor activity through the inhibition of c-Met-Ras-HO-1 axis; and it can have significant therapeutic potential to prevent post-transplantation cancer in immunosuppressed patients.

PEG-functionalized zinc oxide nanoparticles induce apoptosis in breast cancer cells through reactive oxygen species-dependent impairment of DNA damage repair enzyme NEIL2.

We find that PEG functionalized ZnO nanoparticles (NP) have anticancer properties primarily because of ROS generation. Detailed investigation revealed two consequences depending on the level of ROS - either DNA damage repair or apoptosis - in a time-dependent manner. At early hours of treatment, NP promote NEIL2-mediated DNA repair process to counteract low ROS-induced DNA damage. However, at late hours these NP produce high level of ROS that inhibits DNA repair process, thereby directing the cell towards apoptosis. Mechanistically at low ROS conditions, transcription factor Sp1 binds to the NEIL2 promoter and facilitates its transcription for triggering a 'fight-back mechanism' thereby resisting cancer cell apoptosis. In contrast, as ROS increase during later hours, Sp1 undergoes oxidative degradation that decreases its availability for binding to the promoter thereby down-regulating NEIL2 and impairing the repair mechanism. Under such conditions, the cells strategically switch to the p53-dependent apoptosis.

Crocetin exploits p53-induced death domain (PIDD) and FAS-associated death domain (FADD) proteins to induce apoptosis in colorectal cancer.

Tumor suppressor p53 preserves the genomic integrity by restricting anomaly at the gene level. The hotspots for mutation in half of all colon cancers reside in p53. Hence, in a p53-mutated cellular milieu targeting cancer cells may be achievable by targeting the paralogue(s) of p53. Here we have shown the effectiveness of crocetin, a dietary component, in inducing apoptosis of colon cancer cells with varying p53 status. In wild-type p53-expressing cancer cells, p53 in one hand transactivates BAX and in parallel up-regulates p53-induced death domain protein (PIDD) that in turn cleaves and activates BID through caspase-2. Both BAX and t-BID converge at mitochondria to alter the transmembrane potential thereby leading to caspase-9 and caspase-3-mediated apoptosis. In contrast, in functional p53-impaired cells, this phytochemical exploits p53-paralogue p73, which up-regulates FAS to cleave BID through FAS-FADD-caspase-8-pathway. These findings not only underline the phenomenon of functional switch-over from p53 to p73 in p53-impaired condition, but also validate p73 as a promising and potential target for cancer therapy in absence of functional p53.