1 Introduction

Eukaryotic cells undergo many essential cellular processes for survival, from cell growth and motility to intracellular trafficking. The cellular processes rely on interactions of a variety of cellular components such as microtubules, actin filaments and growth factors. Cancer begins when the normal processes that regulate cell behaviour are altered and causes abnormal capabilities such as excessive cell proliferation, uncontrolled invasion and metastasis, unregulated angiogenesis and avoiding destruction by the immune system (Pickup et al., 2014). Globally, cancer is a leading cause of death, such that it becomes one of the most significant public health burdens of the century that has spurred development of various therapeutic drugs that can keep patients alive and well for a longer time.

                  In most cancers, chemotherapy is adopted as the first-line treatment although its efficacy is far from satisfying due to its side effect in damaging surrounding healthy tissues, leading to tissue inflammation and maladaptive remodelling (Octavia et al., 2012). Other limitations of conventional chemotherapy include difficulty in selecting dosage to use and development of drug resistance by the cancer cells (Debela et al., 2021). An alternative option to overcome the lack specificity of chemotherapy that leads to collateral damage is by targeted drug therapy.

Selectively treating cancers with targeted drug has shown to improve survival rate in breast cancer and lung cancer patients (Mener and Aggarwal, 2015; Musika et al, 2021). The mechanism of action of targeted therapies is based on their interaction at the target site. Monoclonal antibodies therapy, for example, allows binding of engineered monoclonal antibodies to cancer cell surface antigens to activate cell destruction through mechanisms including induction of apoptosis, activation of cellular phagocytosis or disruption of tumour blood vessel network (Coulson et al., 2014). While adverse effects of monoclonal antibodies therapy are milder compared with conventional chemotherapy, the production cost to produce such therapeutic monoclonal antibodies is expensive, estimated to be twice than required for conventional drugs (Craik et al., 2013).

Ablation cancer therapy refers to treatment technique that destroys tumours without removal of the cancer cells. This technique offers minimal invasive procedure to surgery, which is performed using methods involving thermal energy, high-intensity ultrasound beam and high-energy laser (Kang and Rhim, 2015). However, tumour ablation is not indicated for certain cases where tumours present near major blood vessels or major bile ducts since the ablation technique may destroy some of the normal tissues near the tumour. Besides, complications such as haemorrhage, hepatic and extrahepatic organ injuries as well as skin burn have been reported following ablation therapy (Koda et al., 2012).

Microtubule-targeting agents (MTAs) are chemical compounds that specifically bind to tubulin and interfere with the properties and functions of microtubules. Because microtubules have distinct functions in proliferation and survival processes, targeting microtubule dynamics becomes a promising anticancer therapy. MTAs are antimitotic agents that suppress cell proliferation, either by inhibiting microtubule polymerization (such as vinblastine, colchicine and combretastatins) or stimulating microtubule polymerization (such as paclitaxel, docetaxel).

Exploration on small organic molecules to be developed as targeted therapy drugs for cancer is constantly emerging, owing to the fact that their structures can be easily modified to suit clinical needs and low-cost production. Phytoestrogens are polyphenolic small molecules that exhibit molecular structure similarity to estrogens, hence allows them to bind to estrogen receptors and exert estrogenic activity (Sayed et al., 2018). While some phytoestrogens have been reported to bind directly to tubulin and alter microtubules dynamics, there are other phytoestrogens that have indirect effects on microtubule stability. This review focuses on microtubule-targeting activity by several phytoestrogens and the future development as new anticancer strategies.

2 Microtubule composition and dynamics

2.1 Composition

Microtubules are made up of one polymerized dimer, ? and ß tubulin, weight around 55 kDa and fold in double helix structure. Microtubules extend and grow to form into long hollow cylinders (Sun et al., 2021). Apart from ? and ß tubulin, there are ?, d and e tubulin families that mainly present in the centrosome. The best-known role of microtubules in eukaryotes is in the formation of cytoskeleton. They control vital cellular activities ranging from cell division, cell movement and intracellular transport (Cermák et al., 2020). Spindle microtubules extend from centrioles to segregate chromosomes during cell division. While in protozoans, microtubules are the structural components that form flagella and cilia.

2.2 Dynamics

Microtubules have two main dynamic states, polymerization and depolymerization. Such change of balance between these states allow microtubules to dynamically alter their organization according to the needs of respective cellular processes, for example in cell cycle and cell division, which involve chromosomes movement and cell division to produce daughter cells. Polymerization of microtubules occurs with addition of a- and ß-tubulin dimers at both ends of microtubules that leads to microtubule growth while dissociation of the tubulin dimers at the ends, known as depolymerization, results in microtubule shrinkage (Horio and Murata, 2014).

The simultaneous presence of both microtubules elongation and shrinkage is required to carry out specialized cell functions. These events are regulated by microtubule-associated proteins (MAP) including Tau, MAP2 and MAP4 that promote stabilizing effect, and depolymerizing MAPs like stathmin, katanin and spastin that regulate microtubule destabilization (Goodson and Jonasson, 2018). The microtubules dynamic activities are demonstrated experimentally by evaluating their growth rate, shortening rate and transition frequency (Mukhtar et al., 2014).

3 Mechanism of action of microtubule-targeting compounds

Several naturally-derived compounds, such as vinca alkaloids and colchicine, are found to inhibit microtubule polymerization while compounds such as taxanes and laulimalides have been shown to encourage microtubule assembly. These compounds are known as microtubule targeting agents (MTAs) and interrupt microtubule stability by binding tubulin at respective sites that have been well characterized as shown in Figure 1 (Barbier et al., 2014). For example, vinblastine, taxol and maytansine bind to the ß-tubulin subunit in microtubules whereas colchicine binds at the a and ß interphase of tubulin. The only natural product shown through crystallographic research that binds a-tubulin is pironetin, a metabolite originally isolated from Streptomyces species (Yang et al., 2016).

The MTAs are grouped into microtubule-stabilizing agents (MSAs) and microtubule-destabilizing agents (MDAs), of which reflects their activities at high concentrations in influencing microtubule mass. MSAs promote microtubules stability while MDAs trigger microtubule disassembly into tubulin dimers. Changes in microtubule dynamics may perturb the formation of mitotic spindle, arrest cell mitosis, restrict cell motility and induce cell death. More researchers have adopted these approaches to investigate better therapy to combat cancer. MTAs that have been approved and introduced into the clinic for the treatment of various cancers include paclitaxel, epothilone and maytansine. Current knowledge on the molecular mechanisms of action of MSAs and MDAs to hijack the microtubule cytoskeleton is emerging and drives the future cancer treatment directions.

Taxane-site ligands; such as paclitaxel, epothilone, zampanolide and taccalonolide, are MSAs that bind to the same pocket on ß-tubulin (Steinmetz and Prota, 2018). The taxane site consists of hydrophobic residues of helix H7, strand S7 and ß-tubulin loops; H6-H7, the M-loop and S9-S10. Upon biding to taxane site, the ligands establish hydrophobic and polar interactions with the structural elements thus promote microtubule assembly and stability. Perturbation on microtubule dynamics is owing to the role of M-loop as the main element that forms lateral contacts in the microtubules.

However, in the case of paclitaxel, it does not exhibit a sidechain to interact with the M-loop but still promotes microtubules stabilization. Following high-resolution cryo-electron microscopy (cryo-EM) studies carried out by Alushin and co-workers (2014), it has been suggested that major mechanism contributes to the microtubule stabilization may not be through a particular M-loop conformation. This is supported by their findings in which the microtubule-stabilizing effect of paclitaxel involves modulation of longitudinal contacts and conformational strain within the tubulin monomers. Collectively, although binding to the same pocket on ß-tubulin, different taxane-site ligands may have different molecular mechanism to exert their microtubule-stabilizing effect.

On the other hand, molecular mechanisms of MDAs involve either inhibition of native tubulin contacts formation or through prevention of tubulin curved-to-straight conformational change that accompanies microtubule formation. Vinca alkaloids are potent MDAs that target vinca site of tubulin. The vinca site comprises of a core zone and a pocket that protrudes into exchangeable GTP-binding site of ß-tubulin (Wang et al., 2016). Vinca-site ligands trigger microtubule destabilization by establishing a ‘wedge’ at the tips of microtubules that prevents correct positioning of a-tubulin hence causes GTP hydrolysis on ß-tubulin and protofilaments disassembly (Ranaivoson et al., 2012). Other well-known MDAs are compounds targeting the colchicine site, a pocket buried deeper in the intermediate domain of ß-tubulin and located at the interface between a- and ß-tubulin subunits. Upon binding to the colchicine site, the ligands form hydrophobic and polar interactions that prevents the movement of intermediate domain of a- and ß-tubulin subunits (Wang et al., 2022). Consequently, the conformational changes of tubulin from a curved conformation to a straight structure, as required for tubulin assembly, is inhibited.

4 Phytoestrogens and microtubule dynamics

Phytoestrogens can be found in diverse food sources such as soy products, fruits and cereals (Torrens-Mas et al., 2020; Kashyap et al., 2017). Medicinal plants, which have been used in traditional practices to treat various diseases, have also been reported to contain phytoestrogens, especially those classified as flavanoids. Flavonoids comprise of several main subgroups, namely prenylflavonoids, coumestans, isoflavones, flavones, chalcones and anthocyanidins. While for the non-flavonoids such as stilbenes, lignans and tannins, they are commonly found in nuts, legumes and whole grains.

Phytoestrogens have been reported to potentially combat cancer by reducing tumour cell survival and growth as well as triggering cell death. For instance, silibinins may prevent migration of highly metastatic breast cancer cells (Lashgarian et al., 2020) while some lignans have been found to suppress mitotic spindle formation and tubulin polymerization in lung adenocarcinoma, ovarian cancer, and neuroblastoma-derived cells (Esfandiari et al., 2017). Kaempferol, one of the extensively studied phytoestrogens, have been reported to diminish 5-fluorouracil drug resistance in LS174 cells (Riahi-Chebbi et al., 2019). Some phytoestrogens with anticancer properties have been found to target microtubules dynamics as their mechanism of action (Mukhtar et al., 2015). Given the important roles of microtubules in most cell physiological events, altering microtubules dynamics may contribute to deleterious impacts to cancer cells to the extent that it often results in cell death.

Quercetin has been found to bind tubulin at colchicine site to promote microtubule depolymerization hence causes cell cycle arrest at G/M phase in prostate carcinoma and breast cancer cells (Almatroodi et al., 2021). Upon binding to tubulin, quercetin stimulates the GTPase activity of soluble tubulin that later perturbs microtubule polymerization dynamics (Gupta and Panda, 2002). Previous study by Novo and co-workers (2015) showed that Wnt/ß-catenin signalling was hindered following quercetin treatment in B-1 lymphocytes, leading to alterations in cell proliferation and differentiation. Since there is evidence to support Wnt/ß-catenin signalling as a crucial antitumor effect of MTAs (Kumari et al., 2021), perhaps anticancer properties of quercetin may also be due to alteration in the Wnt/ß-catenin signalling.

As a naturally occurring isoflavone, podophyllotoxin shows a great potential against diverse types of cancer such as non-small cell lung cancer, breast cancer and hepatocellular carcinoma (Choi et al., 2015; Zhang et al., 2020; Li et al., 2019). Podophyllotoxin-treated lung cancer cells show suppressed cell growth and migration in vitro (Yang et al., 2019). This is consistent with their immunofluorescence data that show disorganization of microtubule structure and spindle formation as well as rearrangement of vimentin filaments following podophyllotoxin treatment in A549 cells. The microtubule disorganization is due to inhibition of microtubule polymerization, which resulted from podophyllotoxin binding to the colchicine site of tubulin with the its 3,4,5-trimethoxybenzoyl at ring-A buried deeply inside the colchicine binding site (Figure 2).

Other potential anticancer phytoestrogens that disrupt microtubules dynamics by promoting microtubule depolymerization are combretastatin, epigallocatechin gallate (EGCG) and theaflavin. While combretastatin binds to colchicine site on the ß-tubulin subunit at its 3,4,5-trimethoxy substituted A ring and the 4-methoxy substituted B ring (Figure 2), EGCG has been found to bind a-subunit of tubulin near colchicine site (Bukhari et al, 2017; Chakrabarty et al., 2015). Although EGCG binding to tubulin does not overlap with the colchicine site, it is more potent than colchicine in promoting microtubule depolymerization. Intriguingly, the mechanism for microtubule depolymerization of theaflavin occurs through vinblastine binding site (Chakrabarty et al., 2019). In the presence of theaflavin, fluorescence intensity of BODIPY FL vinblastine, a fluorescent analogue of vinblastine, is reduced suggesting inhibition of BODIPY FL vinblastine binding to tubulin.

Of phytoestrogens studied for their effects on tubulin, fisetin has been reported to interrupt the dynamic behaviour of microtubules through stimulating microtubules polymerization and stabilizing microtubules at high concentrations (Mukhtar et al., 2015). Fisetin treatment in cancer cells inhibits cellular processes that are closely regulated by cytoskeleton such as cell proliferation and migration. Finding from in vitro tubulin polymerization assay shows that fisetin enhances microtubule polymerization higher than paclitaxel and increases microtubule network stability. Binding evaluations through surface plasmon resonance (SPR) reveals that fisetin interacts with ß-tubulin pocket within paclitaxel binding site. Moreover, expression of microtubule associated proteins (MAPs), MAP-2 and MAP-4, has been found to be increased following fisetin treatment in prostate cancer cells (Mukhtar et al., 2015). These proteins are best known for their important role in microtubule network regulation through microtubule-stabilizing activity (Mohan and John, 2015).

5 Discussion

Naturally-derived compounds that disrupt the normal function of microtubule have been deemed to be one of chemotherapeutic agents work against for various tumour. Compared to biologics, phytoestrogens are relatively small molecules that have multiple biological activities with fewer toxic effects, which perhaps could potentially counteract the drug resistance problems of traditional chemotherapy (Pu et al., 2015). Phytoestrogen that target microtubules has also been shown to overcome cancer cell drug resistance when used in combination with established conventional chemotherapy drugs. For instance, EGCG reverses gefitinib drug resistance in lung cancer cells by elevating cell death through inhibition of ERK phosphorylation (Meng et al., 2019).

Phytoestrogens that do not directly target microtubules for their anticancer activity are also beneficial in improving efficiency of chemotherapeutic drugs. Kaempferol has been shown to reverse drug resistance of LS174 cells to 5-fluorouracil (5-Fu) when used in combination with the chemotherapy drug (Riahi-Chebbi, et al., 2019) while treatment of gastric cancer cells with genistein reduces chemoresistance to 5-Fu as well as cisplatin in vitro and in vivo (Huang et al., 2014). The reduced chemoresistance is owing to suppression of ERK 1/2 activity that significantly diminishes expression of chemoresistant gene ABCG2.

Moreover, the antitumour efficacy of cisplatin against triple negative breast cancer cells can be enhanced using combined treatment with apigenin, which results in inhibition of telomerase activity (Aziz et al., 2017). Resveratrol, a well-known polyphenol, increases chemosensitization effect of human breast cancer cells MCF-7 to melphalan by activating caspases 7 and 9 hences induces cells death (Casanova et al., 2012). Besides, sensitization of resveratrol leads to decreased expression of cyclin A, suggesting cell cycle arrest in the S phase. 

Extensive investigations on co-treatment of phytoestrogens and established MTAs have been performed using drugs such as paclitaxel, docetaxel and vincristine. Combination therapy of resveratrol and paclitaxel leads to further increase of calcium ion (Ca2+) into DBTRG glioblastoma cells through activation of TRPM2 channel contributing to increased cancer cell death (Öztürk et al., 2019). Increased mitochondrial ROS production has also been observed, which causes cytotoxic effects to the cancer cells.

Chemoresistance and side effects of docetaxel can be overcome by using the drug together with EGCG and quercetin as reported by Wang et al., 2015 following treatment in prostate cancer cells. They found that EGCG and quercetin enhance therapeutic impact of docetaxel through various mechanisms including triggers antiproliferative activity, increases apoptosis and inhibits tumour cell invasion. Quercetin has also been shown to enhance oral cancer cells sensitivity to vincristine and significantly increases apoptosis rate (Yuan et al., 2015).

Given the promising anticancer properties of phytoestrogens, using phytoestrogens alone as potential MTAs or as an adjuvant with other chemotherapeutic drugs is an exceptional alternative to resolve limitations of traditional chemotherapy. Development of phytoestrogens as new treatment strategies that leads to lesser side effects and resolves drug resistance could provide a more effective therapeutic alternative for cancer patients. Here we propose future research strategies for combination therapies using phytoestrogens and established anticancer drugs in achieving a safe and effective treatment (Figure 3).

More studies are warranted to comprehend better on the mechanistic role of phytoestrogens to enhance their usage and effectiveness in combating cancer. Modern techniques such as cryo-EM, atomic force microscopy and X-ray crystallography can be adapted to understand detailed molecular mechanisms by which phytoestrogens alter microtubule dynamics. Regarding clinical study design to evaluate the benefit/risk ratio of combination therapy compared with single drug, it is important to report on responder percentages of patients benefit from combined treatment and patients expose to adverse effects in order to avoid overestimating benefits of combination therapy.

6 Conclusion

Collectively, phytoestrogens receive much attention for development as promising chemotherapeutic agents in clinical use due their simple structures, various biological activities and less toxic to healthy cells. With regard to microtubule targeting activities by some of the phytoestrogens, we suggest they could be developed as proliferation and migration inhibitory agents that aim multiple pathways to combat cancer cells survival and invasion. As more studies are being carried out to investigate the potential of phytoestrogens in overcoming drug resistance, it is crucial to design strategies to integrate phytoestrogens as an adjuvant with other chemotherapeutic agent.

Author Contributions

Xu Fan: Writing – Original Draft. Nozlena Abdul Samad: Writing – Review, Supervision. Nurhuda Mohamad Ansor: Conceptualization, Writing – Review and Editing, Supervision.

Acknowledgments

This work was supported by the short-term research grant (304/CIPPT/6315481) from Universiti Sains Malaysia.

References

Almatroodi, S.A., Alsahli, M.A., Almatroudi, A., Verma, A.K., Aloliqi, A., Allemailem K.S., Khan, A.A., & Rahmani, A.H. (2021). Potential therapeutic targets of quercetin, a plant flavonol, and its role in the therapy of various types of cancer through the modulation of various cell signaling pathways. Molecules, 26(5), 1315-1352.

Alushin, G.M., Lander, G.C., Kellogg, E.H., Zhang, R., Baker, D., & Nogales, E. (2014). High-resolution microtubule structures reveal the structural transitions in αβ-tubulin upon GTP hydrolysis. Cell, 157(5), 1117-1129.

Aziz, N.A., Froemming, G.R.A., Sheikh Abdul Kadir, S.H., & Ibrahim, M.J. (2017). Apigenin increases cisplatin inhibitory effects on the telomerase activity of triple negative breast cancer cells. Jurnal Teknologi, 80(1).

Barbier, P., Tsvetkov, P.O., Breuzard, G., & Devred, F. (2014). Deciphering the molecular mechanisms of anti-tubulin plant derived drugs. Phytochemistry Reviews, 13, 157-169.

Bukhari, S.N.A., Kumar, G.B., Revankar, H.M., & Qin, H.L. (2017). Development of combretastatins as potent tubulin polymerization inhibitors. Bioorganic Chemistry, 72, 130-147.

Casanova, F., Quarti, J., da Costa, D.C., Ramos, C.A., da Silva, J.L., & Fialho, E. (2012). Resveratrol chemosensitizes breast cancer cells to melphalan by cell cycle arrest. Journal of Cellular Biochemistry, 113(8), 2586-2596.

Cermák, V., Dostál, V., Jelínek, M., Libusová, L., Kovár, J., Rösel, D., & Brábek, J. (2020). Microtubule-targeting agents and their impact on cancer treatment. European Journal of Cell Biology, 99(4), 151075.

Chakrabarty, S., Ganguli, A., Das, A., Nag, D., & Chakrabarti, G. (2015). Epigallocatechin-3-gallate shows anti-proliferative activity in HeLa cells targeting tubulin-microtubule equilibrium. Chemico-Biological Interactions, 242, 380-389.

Chakrabarty, S., Nag, D., Ganguli, A., Das, A., Ghosh Dastidar, D., & Chakrabarti, G. (2019). Theaflavin and epigallocatechin-3-gallate synergistically induce apoptosis through inhibition of PI3K/Akt signaling upon depolymerizing microtubules in HeLa cells. Journal of Cellular Biochemistry, 120(4), 5987-6003.

Choi, J.Y., Hong, W.G., Cho, J.H., Kim, E.M., Kim, J., Jung, C., Hwang, S., Um, H., & Park J.K. (2015). Podophyllotoxin acetate triggers anticancer effects against non-small cell lung cancer cells by promoting cell death via cell cycle arrest, ER stress and autophagy. International Journal of Oncology, 47, 1257-1265.

Cortes, J., & Roché, H. (2012). Docetaxel combined with targeted therapies in metastatic breast cancer. Cancer Treatment Reviews, 38(5), 387-396.

Coulson, A., Levy, A., & Gossell-Williams, M. (2014). Monoclonal antibodies in cancer therapy: mechanisms, successes and limitations. West Indian Med J., 63(6), 650-654.

Craik, D.J., Fairlie, D.P., Liras, S., & Price, D. (2013). The future of peptide-based drugs. Chem Biol Drug Des., 81, 136–147.

Debela, D.T., Muzazu, S.G., Heraro, K.D., Ndalama, M.T., Mesele, B.W., Haile, D.C., Kitui, S.K., & Manyazewal, T. (2021). New approaches and procedures for cancer treatment: Current perspectives. SAGE Open Med., 9, 20503121211034366.

Esfandiari, M., Sharif, M., Mohamadyar-Toupkanlou, F., Hanaee-Ahwaz, H., Yousefzadi, M., Jafari, A., Hosseinzadeh, S., & Soleimani, M. (2017). Optimization of cell/tissue culture of Linum persicum for production of lignans derivatives including podophyllotoxin. Plant Cell, Tissue and Organ Culture, 133(1), 51-61.    

Goodson, H.V., & Jonasson, E.M. (2018). Microtubules and microtubule-associated proteins. Cold Spring Harb Perspect Biol., 10(6), a022608.

Gupta, K., & Panda, D. (2002). Perturbation of microtubule polymerization by quercetin through tubulin binding: a novel mechanism of its antiproliferative activity. Biochemistry, 41(43), 13029-13038.

Horio, T., & Murata, T. (2014). The role of dynamic instability in microtubule organization. Front. Plant Sci., 5, 511.

Huang, W., Wan, C., Luo, Q., Huang, Z., & Luo, Q. (2014). Genistein-inhibited cancer stem cell-like properties and reduced chemoresistance of gastric cancer. Int J Mol Sci., 15(3), 3432-3443.

Kang, T.W., & Rhim, H. (2015). Recent advances in tumor ablation for hepatocellular carcinoma. Liver Cancer, 4, 176-187.

Kashyap, D., Sharma, A., Tuli, H.S., Sak, K., Punia, S., & Mukherjee, T.K. (2017). Kaempferol-a dietary anticancer molecule with multiple mechanisms of action: Recent trends and advancements. J Funct Foods, 30, 203-219.

Koda, M., Murawaki, Y., Hirooka, Y., Kitamoto, M., Ono, M., Sakaeda, H., Joko, K., Sato, S., Tamaki, K., Yamasaki, T., Shibata, H., Shimoe, T., Matsuda, T., Toshikuni, N., Fujioka, S.I., Ohmoto, K., Nakamura, S., Kariyama, K., Aikata, H., … Tsutsui, A. (2012). Complications of radiofrequency ablation for hepatocellular carcinoma in a multicenter study: an analysis of 16 346 treated nodules in 13 283 patients. Hepatol Res., 42(11), 1058-1064.

Kumari, A., Shriwas, O., Sisodiya, S., Santra, M.K., Guchhait, S.K., Dash, R., & Panda, D. (2021). Microtubule-targeting agents impair kinesin-2-dependent nuclear transport of β-catenin: Evidence of inhibition of Wnt/β-catenin signaling as an important antitumor mechanism of microtubule-targeting agents. FASEB J., 35(4), e21539.

Lashgarian, H.E., Adamii, V., Ghorbanzadeh, V., Chodari, L., Kamali, F., Akbari, S., Dariushnejad, H. (2020). Silibinin inhibit cell migration through downregulation of RAC1 gene expression in highly metastatic breast cancer cell line. Drug Res., 70(10), 478-483.

Li, Y., Huang, T., Fu, Y., Wang, T., Zhao, T., Guo, S., Sun, Y., Yang, Y., & Li, C. (2019). Antitumor activity of a novel dual functional podophyllotoxin derivative involved PI3K/AKT/mTOR pathway. PLoS ONE, 14(9), e0215886.

Mener, A.S., & Aggarwal, A. (2015). Advances in targeted therapy for breast cancer. Fed Pract., 32(Suppl 4), 46S-49S.

Meng, J., Chang, C., Chen, Y., Bi, F., Ji, C., & Liu, W. (2019). EGCG overcomes gefitinib resistance by inhibiting autophagy and augmenting cell death through targeting ERK phosphorylation in NSCLC. Onco Targets Ther., 12, 6033-6043.

Mohan, R., & John, A. (2015). Microtubule-associated proteins as direct crosslinkers of actin filaments and microtubules. IUBMB Life, 67(6), 395-403.

Mukhtar, E., Adhami, V.M., & Mukhtar, H. (2014). Targeting microtubules by natural agents for cancer therapy. Mol Cancer Ther., 13(2), 275-284.

Mukhtar, E., Adhami, V.M., Sechi, M., & Mukhtar, H.  (2015). Dietary flavonoid fisetin binds to β-tubulin and disrupts microtubule dynamics in prostate cancer cells. Cancer Lett., 28, 367(2), 173-183.

Musika, W., Kamsa-Ard, S., Jirapornkul, C., Santong, C., & Phunmanee, A. (2021). Lung cancer survival with Ccrrent therapies and new targeted treatments: a comprehensive update from the Srinagarind Hospital-based cancer registry from (2013 to 2017). Asian Pac J Cancer Prev., 22(8), 2501-2507.

Nightingale, G., & Ryu, J. (2012). Cabazitaxel (jevtana): a novel agent for metastatic castration-resistant prostate cancer. Pharmacy and Therapeutics, 37(8), 440-448.

Novo, M.C., Osugui, L., dos Reis, V.O., Longo-Maugéri, I.M., Mariano, M., & Popi, A.F. (2015). Blockage of Wnt/β-catenin signaling by quercetin reduces survival and proliferation of B-1 cells in vitro. Immunobiology, 220(1), 60-67.

Octavia, Y., Tocchetti, C.G., Gabrielson, K.L., Janssens, S., Crijns, H.J., & Moens, A.L. (2012) Doxorubicin-induced cardiomyopathy: from molecular mechanisms to therapeutic strategies. J Mol Cell Cardiol., 52(6), 1213-1225.

Olazarán-Santibañez, F., Rivera, G., Vanoye-Eligio, V., Mora-Olivo, A., Aguirre-Guzmán, G., Ramírez-Cabrera, M., & Arredondo-Espinoza, E. (2021). Antioxidant and antiproliferative activity of the ethanolic extract of Equisetum myriochaetum and molecular docking of its main metabolites (apigenin, kaempferol, and quercetin) on β-tubulin. Molecules, 26, 443.

Öztürk, Y., Günaydin, C., Yalçin, F., Naziroglu, M., & Braidy, N. (2019). Resveratrol enhances apoptotic and oxidant effects of paclitaxel through TRPM2 channel activation in DBTRG glioblastoma cells. Oxid Med Cell Longev., 2019, 4619865.

Pickup, M.W., Mouw, J.K., & Weaver, V.M. (2014). The extracellular matrix modulates the hallmarks of cancer. EMBO Rep., 15(12), 1243-1253.

Wang, P., Yang, H.L., Yang, Y.J., Wang, L., & Lee, S.C. (2015). Overcome cancer cell drug resistance using natural products. Evidence-Based Complementary and Alternative Medicine, 2015, Article ID 767136.

Ranaivoson, F.M., Gigant, B., Berritt, S., Joullié, M., & Knossow, M. (2012). Structural plasticity of tubulin assembly probed by vinca-domain ligands. Acta Crystallogr D Biol Crystallogr., 68(Pt 8), 927-934.

Riahi-Chebbi, I., Souid, S., Othman, H., Haoues, M., Karoui, H., Morel, A., Srairi-Abid, N., Essafi, M., & Essafi-Benkhadir, K. (2019). The phenolic compound kaempferol overcomes 5-fluorouracil resistance in human resistant LS174 colon cancer cells. Sci Rep., 9, 195.

Sayed, A.A., & Elfiky A.A. (2018). In silico estrogen-like activity and in vivo osteoclastogenesis inhibitory effect of Cicer arietinum extract. Cell Mol Biol., 64(5), 29-39.

Steinmetz, M.O., & Prota, A.E. (2018). Microtubule-targeting agents: strategies to hijack the cytoskeleton. Trends Cell Biol., 28(10), 776-792.

Sun, X.L., Xie, Y.R., Zhang, N., Zi, C.T., Wang, X.J., & Sheng, J. (2021). Recent advances on small-molecule tubulin inhibitors. Med Res., 5, 200024.           

Torrens-Mas, M., & Roca, P. (2020). Phytoestrogens for cancer prevention and treatment. Biol., 9(12), 427-445.

Wang, J., & Huang, S. (2018). Fisetin inhibits the growth and migration in the A549 human lung cancer cell line via the ERK1/2 pathway. Exp Ther Med., 15(3), 2667-2673.

Wang, J., Miller, D.D., & Li, W. (2022). Molecular interactions at the colchicine binding site in tubulin: An X-ray crystallography perspective. Drug Discov Today, 27(3), 759-776.

Wang, P., Henning, S.M., Heber, D., & Vadgama, J.V. (2015). Sensitization to docetaxel in prostate cancer cells by green tea and quercetin. J Nutr Biochem., 26(4), 408-415.

Wang, Y., Benz, F.W., Wu, Y., Wang, Q., Chen, Y., Chen, X., Li, H., Zhang, Y., Zhang, R., & Yang, J. (2016). Structural insights into the pharmacophore of vinca domain inhibitors of microtubules. Mol Pharmacol., 89(2), 233-242.

Xiao, Y., Liu, Y., Gao, Z., Li, X., Weng, M., Shi, C., Wang, C., & Sun, L. (2021). Fisetin inhibits the proliferation, migration and invasion of pancreatic cancer by targeting PI3K/AKT/mTOR signaling. Aging (Albany NY), 13(22), 24753-24767.

Yang, C., Xie, Q., Zeng, X., Tao, N., Xu, Y., Chen, Y., Wang, J., & Zhang, L. (2019). Novel hybrids of podophyllotoxin and formononetin inhibit the growth, migration and invasion of lung cancer cells. Bioorg Chem., 85, 445-454.

Yang, J., Wang, Y., Wang, T., Jiang, J., Botting, C.H., Liu, H., Chen, Q., Yang, J., Naismith, J.H., Zhu, X., & Chen, L. (2016). Pironetin reacts covalently with cysteine-316 of α-tubulin to destabilize microtubule. Nat Commun., 7, 12103.

Yuan, Z., Wang, H., Hu, Z., Huang, Y., Yao, F., Sun, S., & Wu, B. (2015). Quercetin inhibits proliferation and drug resistance in KB/VCR oral cancer cells and enhances its sensitivity to vincristine. Nutr Cancer, 67(1), 126-136.

Zhang, W., Liu, C., Li, J., Liu, R., Zhuang, J., Feng, F., Yao, Y., & Sun, C. (2020). Target analysis and mechanism of podophyllotoxin in the treatment of triple-negative breast cancer. Front. Pharmacol., 11, 1211.