South Asian Medicinal Compounds as Modulators of Resistance to Chemotherapy and Radiotherapy

Chemosensitizing potential of andrographolide in P-glycoprotein overexpressing multidrug-resistant cancer cell lines

The P-glycoprotein (P-gp) plays a major role in the efflux of chemotherapeutic drugs and significantly limits chemotherapy efficacy. Chemosensitizers augment the therapeutic effects of anticancer agents by overcoming drug resistance mechanisms. In this study, the chemosensitizing property of andrographolide (Andro) in P-gp overexpressing multidrug-resistant (MDR) colchicine-selected KBChR 8-5 cells was evaluated. Molecular docking studies showed Andro exhibits higher binding interaction with P-gp than the other two ABC-transporters studied. Further, it inhibits P-gp transport function in a concentration dependant manner in the colchicine-selected KBChR 8-5 cells. Moreover, Andro downregulates P-gp overexpression via NF-κB signaling in these MDR cell lines. MTT-based cell-based assay illustrates that Andro treatment augments the PTX effect in the KBChR 8-5 cells. Further, the Andro plus PTX combination showed enhanced apoptotic cell death in KBChR 8-5 cells compared with PTX alone treatment. Therefore, the results showed that Andro enhances PTX therapeutic effect in the drug-resistant KBChR 8-5 cells.

Application of Cyclodextrin for Cancer Immunotherapy

Tumor immunotherapy, compared with other treatment strategies, has the notable advantage of a long-term therapeutic effect for preventing metastasis and the recurrence of tumors, thus holding great potential for the future of advanced tumor therapy. However, due to the poor water solubility of immune modulators and immune escape properties of tumor cells, the treatment efficiency of immunotherapy is usually significantly reduced. Cyclodextrin (CD) has been repeatedly highlighted to be probably one of the most investigated building units for cancer therapy due to its elegant integration of an internal hydrophobic hollow cavity and an external hydrophilic outer surface. The application of CD for immunotherapy provides new opportunities for overcoming the aforementioned obstacles. However, there are few published reviews, to our knowledge, summarizing the use of CD for cancer immunotherapy. For this purpose, this paper provides a comprehensive summary on the application of CD for immunotherapy with an emphasis on the role, function, and reported strategies of CD in mediating immunotherapy. This review summarizes the research progress made in using CD for tumor immunotherapy, which will facilitate the generation of various CD-based immunotherapeutic delivery systems with superior anticancer efficacy.

Caffeic acid phenethyl ester: A review on its pharmacological importance, and its association with free radicals, COVID-19, and radiotherapy

Caffeic acid phenethyl ester (CAPE), a main active component of propolis and a flavonoid, is one of the natural products that has attracted attention in recent years. CAPE, which has many properties such as anti-cancer, anti-inflammatory, antioxidant, antibacterial and anti-fungal, has shown many pharmacological potentials, including protective effects on multiple organs. Interestingly, molecular docking studies showed the possibility of binding of CAPE with replication enzyme. In addition, it was seen that in order to increase the binding security of the replication enzyme and CAPE, modifications can be made at three sites on the CAPE molecule, which leads to the possibility of the compound working more powerfully and usefully to prevent the proliferation of cancer cells and reduce its rate. Also, it was found that CAPE has an inhibitory effect against the main protease enzyme and may be effective in the treatment of SARS-CoV-2. This review covers in detail the importance of CAPE in alternative medicine, its pharmacological value, its potential as a cancer anti-proliferative agent, its dual role in radioprotection and radiosensitization, and its use against coronavirus disease 2019 (COVID-19).

Cytotoxic and chemomodulatory effects of Phyllanthus niruri in MCF-7 and MCF-7ADR breast cancer cells

The members of the genus Phyllanthus have long been used in the treatment of a broad spectrum of diseases. They exhibited antiproliferative activity against various human cancer cell lines. Breast cancer is the most diagnosed cancer and a leading cause of cancer death among women. Doxorubicin (DOX) is an anticancer agent used to treat breast cancer despite its significant cardiotoxicity along with resistance development. Therefore, this study was designed to assess the potential cytotoxicity of P. niruri extracts (and fractions) alone and in combination with DOX against naïve (MCF-7) and doxorubicin-resistant breast cancer cell lines (MCF-7^ADR). The methylene chloride fraction (CH₂Cl₂) showed the most cytotoxic activity among all tested fractions. Interestingly, the CH₂Cl₂-fraction was more cytotoxic against MCF-7^ADR than MCF-7 at 100 µg/mL. At sub-cytotoxic concentrations, this fraction enhanced the cytotoxic effect of DOX against the both cell lines under investigation (IC₅₀ values of 0.054 µg/mL and 0.14 µg/mL vs. 0.2 µg/mL for DOX alone against MCF-7) and (1.2 µg/mL and 0.23 µg/mL vs. 9.9 µg/mL for DOX alone against MCF-7^ADR), respectively. Further, TLC fractionation showed that B2 subfraction in equitoxic combination with DOX exerted a powerful synergism (IC₅₀ values of 0.03 µg/mL vs. 9.9 µg/mL for DOX alone) within MCF-7^ADR. Untargeted metabolite profiling of the crude methanolic extract (MeOH) and CH₂Cl₂ fraction exhibiting potential cytotoxicity was conducted using liquid chromatography diode array detector-quadrupole time-of-flight mass spectrometry (LC-DAD-QTOF). Further studies are needed to separate the active compounds from the CH₂Cl₂ fraction and elucidate their mechanism(s) of action.

Phytochemical Targeting of Mitochondria for Breast Cancer Chemoprevention, Therapy, and Sensitization

Breast cancer is a common and deadly disease that causes tremendous physical, emotional, and financial burden on patients and society. Early-stage breast cancer and less aggressive subtypes have promising prognosis for patients, but in aggressive subtypes, and as cancers progress, treatment options and responses diminish, dramatically decreasing survival. Plants are nutritionally rich and biologically diverse organisms containing thousands of metabolites, some of which have chemopreventive, therapeutic, and sensitizing properties, providing a rich source for drug discovery. In this study we review the current landscape of breast cancer with a central focus on the potential role of phytochemicals for treatment, management, and disease prevention. We discuss the relevance of phytochemical targeting of mitochondria for improved anti-breast cancer efficacy. We highlight current applications of phytochemicals and derivative structures that display anti-cancer properties and modulate cancer mitochondria, while describing future applicability and identifying areas of promise.

Combination of levofloxacin and cisplatin enhances anticancer efficacy via co-regulation of eight cancer-associated genes

Chemosensitizer or combined chemotherapy can sensitize cancer cells to therapy and minimize drug resistance. We reveal that levofloxacin has broad-spectrum anticancer activity. Here we report that combination of levofloxacin and cisplatin further enhanced cytotoxicity in cancer cells by further promotion of apoptosis. Levofloxacin concentration-dependently promoted the inhibition of clone formation in cancer cells treated by cisplatin, and their combination further suppressed the tumor growth in mice. Levofloxacin and cisplatin co-regulated genes in directions supporting the enhancement of anticancer efficacy, of which, THBS1, TNFAIP3, LAPTM5, PI3 and IL24 were further upregulated, NCOA5, SRSF6 and SFPQ were further downregulated. Out of the 24 apoptotic pathways significantly enriched in the combination group, TNFAIP3, THBS1, SRSF6 and SFPQ overlapped in 14, 13, 3 and 1 pathway respectively. Jak-STAT/Cytokine-cytokine receptor interaction pathway network and extrinsic apoptotic signaling pathway were significantly enriched in levofloxacin group, cisplatin group and combination group. Jak-STAT/Cytokine-cytokine receptor interaction/Focal adhesion/EMC-receptor interaction pathway network was significantly enriched in the combination group, and IL24 and THBS1 were the overlapped genes. In conclusion, enhancement of anticancer efficacy in combination group was associated with the further regulation of THBS1, TNFAIP3, LAPTM5, PI3, IL24 and NCOA5, SFPQ, SRSF6. Targeting of Jak-STAT/Cytokine-cytokine receptor interaction/Focal adhesion/EMC-receptor interaction pathway network was correlated to the enhancement. With additional benefit to cancer patients for treatment or prophylaxis of an infectious syndrome, levofloxacin can benefit cancer chemotherapy no matter it is used independently or used with other chemotherapeutic drugs.

Sesamol Augments Paclitaxel-Induced Apoptosis in Human Cervical Cancer Cell Lines

Natural medicinal compounds have gained increasing attention as adjuvants during cancer chemotherapy. The present study demonstrated the chemosensitizing effect of sesamol, a natural phenolic compound, in HeLa cell lines In Vitro. Sesamol-pretreated (10 μM) HeLa cells were exposed to 7.5 nM paclitaxel. The chemosensitization was estimated by MTT-based metabolic assay. Further, oxidative DNA damage, alterations in mitochondrial membrane potential (MMP), and apoptotic morphological changes were analyzed. Sesamol treatment before paclitaxel treatment significantly decreased the IC₅₀ value of paclitaxel (7.5 nM) in a concentration-dependent manner. Further, Sesamol treatment before paclitaxel increased the intracellular ROS levels and enhanced apoptosis through MMP alterations. Moreover, there was an increased % of tail DNA in sesamol + paclitaxel-treated cervical cancer cells compared to paclitaxel alone treatment. The frequency of apoptotic cells were also increased during sesamol + paclitaxel treatment cells compared to paclitaxel alone treatment. Thus, Sesamol treatment before paclitaxel exposure enhanced the apoptotic cell death in the HeLa cell lines. The results of the present study were in support of the usage of natural medicinal compounds for clinical chemotherapy after systematic animal experimentations.

Antibiotic resistance modifying ability of phytoextracts in anthrax biological agent Bacillus anthracis and emerging superbugs: a review of synergistic mechanisms

Background and objectives

The chemotherapeutic management of infections has become challenging due to the global emergence of antibiotic resistant pathogenic bacteria. The recent expansion of studies on plant-derived natural products has lead to the discovery of a plethora of phytochemicals with the potential to combat bacterial drug resistance via various mechanisms of action. This review paper summarizes the primary antibiotic resistance mechanisms of bacteria and also discusses the antibiotic-potentiating ability of phytoextracts and various classes of isolated phytochemicals in reversing antibiotic resistance in anthrax agent Bacillus anthracis and emerging superbug bacteria.

Methods

Growth inhibitory indices and fractional inhibitory concentration index were applied to evaluate the in vitro synergistic activity of phytoextract-antibiotic combinations in general.

Findings

A number of studies have indicated that plant-derived natural compounds are capable of significantly reducing the minimum inhibitory concentration of standard antibiotics by altering drug-resistance mechanisms of B. anthracis and other superbug infection causing bacteria. Phytochemical compounds allicin, oleanolic acid, epigallocatechin gallate and curcumin and Jatropha curcas extracts were exceptional synergistic potentiators of various standard antibiotics.

Conclusion

Considering these facts, phytochemicals represents a valuable and novel source of bioactive compounds with potent antibiotic synergism to modulate bacterial drug-resistance.

An evidence mapping and scientometric analysis of the top-100 most cited clinical trials of anti-PD-1/PD-L1 drugs to treat cancers

OBJECTIVE

To gain a deeper understanding of the hot topics and future prospects of programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitors treatment of cancer through scientometric analysis of the top-100 most cited clinical trials.

MATERIALS AND METHODS

We searched the Web of Science Core Collection database from 1980 to June 2019. Two reviewers independently screened the top-100 most cited clinical trials that defined by the National Institutes of Health starting from the most cited article. Title, year of publication, citations, type of cancer, and focused aspects of outcomes were extracted from included clinical trials. VOSviewer software (version 1.6.9) and Excel 2016 were used to do statistical analysis. The evidence mapping was used to present the relationship between cancers, drugs, citations, and outcomes, etc. RESULTS: The top-100 most cited clinical trials published from 2010 to 2018 in nine journals with high impact factor (IF) (IF₂₀₁₈:6.68-70.67), and Lancet Oncology (USA) published the most clinical trials (n = 29, IF₂₀₁₈ = 35.3856). The total number of citations of the top-100 most cited clinical trials was from 59 to 5606. 920 authors from 34 countries and 458 organizations participated in publishing the top-100 most cited clinical trials. The USA (n = 95) and Memorial Sloan-Kettering Cancer Center (n = 31) contributed the most publications. Based on the evidence mapping, there are 25 different types of cancers (e.g. lung cancer, melanoma, and renal cell cancer) and five focused aspects of outcomes (e.g. safety and efficacy).

CONCLUSION

The USA was the dominant country. Anti-PD-1/PD-L1 drugs were widely used to treat lung cancer, melanoma, renal cell cancer, and Hodgkin lymphoma. More exploration should be done to explore the use of anti-PD-1/PD-L1 drugs to treat more type of cancers in future research.

Breaking the Silence of Tumor Response: Future Prospects of Targeted Radionuclide Therapy

Therapy-induced tumor resistance has always been a paramount hurdle in the clinical triumph of cancer therapy. Resistance acquired by tumor through interventions of chemotherapeutic drugs, ionizing radiation, and immunotherapy in the patientsis a severe drawback and major cause of recurrence of tumor and failure of therapeutic responses. To counter acquired resistance in tumor cells, several strategies are practiced such as chemotherapy regimens, immunotherapy, and immunoconjugates, but the outcome is very disappointing for the patients as well as clinicians. Radionuclide therapy using alpha or beta-emitting radionuclide as payload became state-of-the-art for cancer therapy. With the improvement in dosimetric studies, development of high-affinity target molecules, and design of several novel chelating agents which provide thermodynamically stable complexes in vivo, the scope of radionuclide therapy has increased by leaps and bounds. Additionally, radionuclide therapy along with the combination of chemotherapy is gaining importance in pre-clinics, which is quite encouraging. Thus, it opens an avenue for newer cancer therapy modalities where chemotherapy, radiation therapy, and immunotherapy are unable to break the silence of tumor response. This article describes, in brief, the causes of tumor resistance and discusses the potential of radionuclide therapy to enhance tumor response.

Personalized medicine: Stem cells in colorectal cancer treatment

Treatment failure in primary as well as metastatic cancer patients, caused by chemo and radioresistance, has reinforced the research for the applicability of personalized medicine. The use of stem cells (SCs) and cancer stem cells (CSCs) in such a treatment approach will be reviewed in this study. Colorectal cancer (CRC) SCs prove to be a promising asset for CRC treatment optimization both by serving as biomarkers for the current therapy modalities, by means of treatment personalization and patient/tumor stratification, as well as in the development of targeted therapies, selective for the stem cell population. Similar conclusions are drawn, regarding mesenchymal stromal cells (MSCs) and their effect in CRC therapy; while resident stromal cells (RSCs) of tumor microenvironment (TME) seem to promote the tumorigenic and metastatic processes in addition to conferring to the chemo- and radioresistance, under certain conditions they are able to improve the treatment outcome of CRC chemotherapy, e.g. by targeted enzyme/prodrug treatment of CRC cells. This review, points out the dynamic potential of CSCs and other SCs types in CRC treatment personalization as well as, in the improvement of current treatment approaches, opting to a higher therapeutic rate, improved prognosis, survival and quality of life for CRC patients.

Rab GTPases: Central Coordinators of Membrane Trafficking in Cancer

Tumor progression involves invasion, migration, metabolism, autophagy, exosome secretion, and drug resistance. Cargos transported by membrane vesicle trafficking underlie all of these processes. Rab GTPases, which, through coordinated and dynamic intracellular membrane trafficking alongside cytoskeletal pathways, determine the maintenance of homeostasis and a series of cellular functions. The mechanism of vesicle movement regulated by Rab GTPases plays essential roles in cancers. Therefore, targeting Rab GTPases to adjust membrane trafficking has the potential to become a novel way to adjust cancer treatment. In this review, we describe the characteristics of Rab GTPases; in particular, we discuss the role of their activation in the regulation of membrane transport and provide examples of Rab GTPases regulating membrane transport in tumor progression. Finally, we discuss the clinical implications and the potential as a cancer therapeutic target of Rab GTPases.

Targeting the hallmarks of cancer: the effects of silibinin on proliferation, cell death, angiogenesis, and migration in colorectal cancer

Background

Silibinin, as a chemopreventive agent, has shown anti-cancer efficacy against different types of cancers. In the present study, we investigated the anti-cancer activities of silibinin on CT26 mouse colon cell line.

Methods

CT26 cells were treated with different concentrations of silibinin. To examine the cytotoxic effect of silibinin on proliferation, apoptosis, autophagy, angiogenesis, and migration, MTT, colony-forming assay, Annexin V/PI flow cytometry, RT-qPCR, and Scratch assay were used.

Results

Silibinin was found to significantly reduce CT26 cells survival. Furthermore, silibinin strongly induced apoptosis and autophagy by up-regulating the expression of Bax, Caspase-3, Atg5, Atg7 and BECN1 and down-regulating Bcl-2. Silibinin considerably down-regulated the expression of COX-2, HIF-1α, VEGF, Ang-2, and Ang-4 as well as the expression of MMP-2, MMP-9, CCR-2 and CXCR-4.

Conclusions

The present study revealed that silibinin shows anticancer activities by targeting proliferation, cell survival, angiogenesis, and migration of CT26 cells.

Ethnobotany, Phytochemistry and Pharmacological Features of Centella asiatica: A Comprehensive Review

Centella asiatica (CA) or Gotu cola is an herbal plant from the Apiaceae family with a long history of usage in different traditional medicines. It has long been used for the treatment of various ailments such as central nervous system (CNS), skin and gastrointestinal disorders especially in the Southeast Asia. This chapter focused on the phytochemical constituent and pharmacological activities of CA based on preclinical and clinical studies. Additionally, botanical description and distribution, traditional uses, interactions, and safety issues are reviewed. Electronic databases of Google Scholar, Scopus, PubMed, and Web of Science were searched to obtain relevant studies on the pharmacological activities of CA. Approximately, 124 chemical compounds including triterpenoids, polyphenolic compounds, and essential oils have been isolated and identified from CA. Ethnomedicinal applications of CA mostly include treatment of gastrointestinal diseases, wounds, nervous system disorders, circulatory diseases, skin problems, respiratory ailments, diabetes and sleep disorders in various ethnobotanical practices. Pharmacological studies revealed a wide range of beneficial effects of CA on CNS, cardiovascular, lung, liver, kidney, gastrointestinal, skin, and endocrine system. Among them, neuroprotective activity, wound healing and treatment of venous insufficiency, as well as antidiabetic activity seem to be more frequently reported. At the moment, considering various health benefits of CA, it is marketed as an oral supplement as well as a topical ingredient in some cosmetic products. Additional preclinical studies and particularly randomized controlled trials are needed to clarify the therapeutic roles of CA.

Withania somnifera (L.) Dunal: A potential therapeutic adjuvant in cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera (L.) Dunal (WS) is one of the moststudied Rasayana botanicals used in Ayurveda practice for its immunomodulatory, anti-aging, adaptogenic, and rejuvenating effects. The botanical is being used for various clinical indications, including cancer. Several studies exploring molecular mechanisms of WS suggest its possible role in improving clinical outcomes in cancer management. Therefore, research on WS may offer new insights in rational development of therapeutic adjuvants for cancer.

AIM OF THIS REVIEW

The review aims at providing a detailed analysis of in silico, in vitro, in vivo, and clinical studies related to WS and cancer. It suggests possible role of WS in regulating molecular mechanisms associated with carcinogenesis. The review discusses potential of WS in cancer management in terms of cancer prevention, anti-cancer activity, and enhancing efficacy of cancer therapeutics.

MATERIAL AND METHODS

The present narrative review offers a critical analysis of published literature on WS studies in cancer. The reported studies were analysed in the context of pathophysiology of cancer, commonly referred as 'cancer hallmarks'. The review attempts to bridge Ayurveda knowledge with biological insights into molecular mechanisms of cancer.

RESULTS

Critical analysisof the published literature suggests an anti-cancer potential of WS with a key role in cancer prevention. The possible mechanisms for these effects are associated with the modulation of apoptotic, proliferative, and metastatic markers in cancer. WS can attenuate inflammatory responses and enzymes involved in invasion and metastatic progression of cancer.The properties of WS are likely to be mediated through withanolides, which may activate tumor suppressor proteins to restrict proliferation of cancer cells. Withanolides also regulate the genomic instability, and energy metabolism of cancer cells. The reported studies indicate the need for deeper understanding of molecular mechanisms of WS in inhibiting angiogenesis and promoting immunosurveillance. Additionally, WS can augment efficacy and safety of cancer therapeutics.

CONCLUSION

The experimentally-supported evidence of immunomodulatory, anti-cancer, adaptogenic, and regenerative attributes of WS suggest its therapeutic adjuvant potential in cancer management. The adjuvant properties of withanolides can modulate multidrug resistance and reverse chemotherapy-induced myelosuppression. These mechanisms need to be further explored in systematically designed translational and clinical studies that will pave the way for integration of WS as a therapeutic adjuvant in cancer management.

The role of HIF-1α in chemo-/radioresistant tumors

Chemo-/radioresistance is a major obstacle in clinical oncology. The precise failure mechanisms of chemo-/radioresistance are multifactorial failures. It is now widely accepted that a tumor hypoxia microenvironment contributes significantly to chemo-/radioresistance. Hypoxia is the most common and obvious neoplastic microenvironment and is due to the rapid proliferation of tumor cells. HIF-1α is a principal molecular mediator of adaptability to hypoxia in tumor cells. HIF-1α activation leads to the transcription of a plethora of target genes that promote physiological changes associated with chemo-/radioresistance, including increasing the ability of DNA repair, the inhibition of apoptosis, and alterations of the cellular metabolism. Moreover, recent findings suggest that HIF-1α-activated autophagy is a crucial factor in the promotion of cell survival under the distressed microenvironment, thereby leading to the chemo-/radioresistance. This chapter presents an overview of the role of HIF-1α in chemo-/radioresistance of tumor cells.

Activation of the CRABPII/RAR pathway by curcumin induces retinoic acid mediated apoptosis in retinoic acid resistant breast cancer cells

Due to the anti-proliferative and anti-apoptotic effects of retinoic acid (RA), this hormone has emerged as a target for several diseases, including cancer. However, development of retinoid resistance is a critical issue and efforts to understand the retinoid signaling pathway may identify useful biomarkers for future clinical trials. Apoptotic responses of RA are exhibited through the cellular RA-binding protein II (CRABPII)/retinoic acid receptor (RAR) signaling cascade. Delivery of RA to RAR by CRABPII enhances the transcriptional activity of genes involved in cell death and cell cycle arrest. The purpose of this study was to investigate the role of curcumin in sensitizing RA-resistant triple-negative breast cancer (TNBC) cells to RA-mediated apoptosis. We provide evidence that curcumin upregulates the expression of CRABPII, RARβ and RARγ in two different TNBC cell lines. Co-treatment of the cells with curcumin and RA results in increased apoptosis as demonstrated by elevated cleavage of poly(ADP-ribose) polymerase and cleaved caspase-9. Additionally, silencing CRABPII reverses curcumin sensitization of TNBC cells to the apoptotic inducing effects of RA. These findings provide mechanistic insights into sensitizing TNBC cells to RA-mediated cell death by curcumin-induced upregulation of the CRABPII/RAR pathway.

Curcumin Sensitizes Silymarin to Exert Synergistic Anticancer Activity in Colon Cancer Cells

We studied combinatorial interactions of two phytochemicals, curcumin and silymarin, in their action against cancer cell proliferation. Curcumin is the major component of the spice turmeric. Silymarin is a bioactive component of milk thistle used as a protective supplement against liver disease. We studied antiproliferative effects of curcumin alone, silymarin alone and combinations of curcumin and silymarin using colon cancer cell lines (DLD-1, HCT116, LoVo). Curcumin inhibited colon cancer cell proliferation in a concentration-dependent manner, whereas silymarin showed significant inhibition only at the highest concentrations assessed. We found synergistic effects when colon cancer cells were treated with curcumin and silymarin together. The combination treatment led to inhibition of colon cancer cell proliferation and increased apoptosis compared to single compound treated cells. Combination treated cells exhibited marked cell rounding and membrane blebbing of apoptotic cells. Curcumin treated cells showed 3-fold more caspase3/7 activity whereas combination treated cells showed 5-fold more activity compared to control and silymarin treated cells. When DLD-1 cells were pre-exposed to curcumin, followed by treatment with silymarin, the cells underwent a high amount of cell death. The pre-exposure studies indicated curcumin sensitization of silymarin effect. Our results indicate that combinatorial treatments using phytochemicals are effective against colorectal cancer.