1.1 The benefits of CHM
The CHM herbs can be classified according to their properties. The use of specific herb(s) to treat diseases depends on the sign and symptom of patients or their conditions. The herbalists believe that the illness is the imbalance
condition of the body. Based on their various characteristics which are in accordance with the law of nature, can neutralize the sign and the symptoms thereby keeping an overall balanced status in patient’s body [1].
CHM has been used as a front line medicine by the majority of the
world’s population since before the recorded history, and is still the most widely utilized medical system in the world today. Adverse reactions to Chinese herbs are generally rare when compared with those commonly produced by
pharmaceutical drugs. CHM is a medical system that is capable of treating disease in various forms [2]. The clinical aspects of CHM include differential diagnosis and treatments based on the analysis of signs and symptoms and differentiation of syndromes. The treatment is known for its sophistication in addressing clinical concerns while remedying an individual’s particular needs.
The art of selecting the appropriate base herbal formula is dependent on this analysis and the modifications made according to the presenting signs and symptoms of the patient [3]. Upon completing the study of the fundamental theories of CHM, diagnosis, pathology, students and new practitioners become concerned with how to apply their knowledge in clinical settings, with the selection of appropriate formulae, and with the modification process according to the manifestations or sometimes to the conventional diagnoses [4].
1.2 BJ as a conventional medicine
BJ, a shrub original from south-east Asia and northern Australia and known in CHM for anti-cancer properties. In traditional herbal medicine, the seed of this plant also has been used for other treatment of different diseases including diabetes in Malaya peninsula [5].
Recently the medicine Fructus Bruceae (Yadanzi in Chinese) in NSCLC treatment has been practiced in China by many clinical treatment cases. Yadanzi (Fructus Bruceae) is the dried ripe fruit of Brucea javanica (L.) Merr
Simaroubaceae [6]. As an efficient and safe traditional Chinese herbal medicine, it has been used to treat parasite infections or malarial in China for thousands years. It also shows huge effects in cancer therapy [7]. For instance, recipe of Yadanzi and its oil emulsions have been studied and already commercialized in China to treat various types of cancer such as brain cancer, lung cancer and gastrointestinal cancer, especially NSCLC [8]. It was already determined that the oleic acids or linoleic acids, two major components of Yadanzi oil, may cause anti-cancer activities. These two major components suppressed DNA Topoisomerases-I or-II [1]. Also these components could induce cancer cell death by up-regulation of caspase-3 and -9 or inhibition of NF-kappa B and cyclooxygenase 2 [2]. Moreover, some kusulactones of Yadanzi extract have been shown with anticancer activities. For example, brusatol was found as an effective compound in anti-inflammation, anti-leukaemia and enhancement of neoplastic chemotherapy [3, 6, 7]. The anti-cancer activities were anticipated involving nuclear factor (erythroid-derived 2)-like 2-mediated defense
mechanism and the activation and translocation of NF-kappa B into the nucleus.
Bruceantin is another Yadanzi ingredient that has been studied for Phase II trials in treating metastatic breast carcinoma and malignant melanoma respectively. It
ribosomal translation by targeting ribosome peptidyltransferase [9]. It was also found that bruceantin could induce apoptotic cell death by down-regulation of c-MYC and activate of caspase activities in mitochondria. Brusatol, bruceantin and several active ingredients like bruceine B and bruceine D were investigated for their potential activities in anti-cancers and anti-inflammation [10, 11].
1.3 The prevalent lung cancer
Human lung cancer is the leading cause of cancer-related deaths
worldwide and NSCLC is the most prevalent type of lung cancers which is hard to be diagnosed in patients with advanced-stage disease. Recently, about 16 different drugs have been used in NSCLC treatment including gefitinib, erlotinib. Unfortunately, the protein target-based chemotherapy sometimes failed to work because of the problem of drug resistance [12].
1.4 EGFR in lung cancer
NSCLC is responsible for ≤ 80% of all cases of lung cancer, and
advanced diseases are commonly found at the time of diagnosis. Almost 10% of patients with NSCLC in the US and 35% in East Asia have tumor associated with EGFR mutations. Lung cancer is characterized with frequent aberrance in driver genes, specifically EGFR [13]. Patients with mutations in the EGFR gene are sensitive to treatment with EGFR TKIs. The first generation EGFR TKIs, gefitinib and erlotinib, reversibly suppress binding of ATP to the intracellular catalytic domain of EGFR tyrosine kinase, preventing EGFR activation and subsequent downstream signaling. However, despite an initial response to treatment with first-generation EGFR TKIs, most EGFR mutation-positive
patients will develop resistance after 9–12 months of treatment [14]. Also, resistance will eventually develop in all patients after various time periods. The acquired resistance to gefitinib is most usually conferred upon a patient by the EGFR T790M mutation, which has been detected in 50% of NSCLC cases in cell line models. This mutation causes steric hindrance, thus preventing binding of EGFR TKIs, by inducing the affinity of the kinase for ATP and reducing inhibitor efficacy. The second-generation irreversible EGFR TKIs (e.g., afatinib and dacomitinib) have shown preclinical therapeutic value to overcoming
EGFR T790M [15]. However, they are ineffective in preventing the physiologic action or the emergence of T790M and have shown limited clinical efficiency due to their non-selective inhibition of wild-type EGFR in causing dose-limiting toxicity. Due to the limited treatment options available for individuals with advanced lung cancer, a requirement exists for the identification of novel therapeutic strategies.
The emulsified formula of BJ has been approved to treat various mutated EGFR frequently occurred in lung adenocarcinoma patients, especially those of Asian ethnicity, females, and nonsmokers. Both of gefitinib and erlotinib serve as the first-line TKI therapy to treat advanced NSCLC patients harboring EGFR mutation by preventing dimerization and phosphorylation of the receptor [16].
As first choice for target therapy, gefitinib and erlotinib bind to L858R EGFR of lung cancer cells, thereby making treatment successful [16, 17]. Treatment of TKI significantly prolonged survival rates of lung cancers patients with the specifically mutated EGFR [18]. Despite their distinct response, lung cancer patients receiving target therapy eventually develop resistance due to the evolved secondary T790M mutation. The rate arises at a median of 10–13 months that occurs in more than 50% of the patients [19]. In order to overcome the high concentration toxicity and resistance because of the accumulated
somatic mutation of T790M EGFR, new development of safer and more useful medication following target therapy is needed.
1.5 The CSCs hypothesis and drug resistance
Tissue stem cells form a small population of cells (typically much less than 1% within tissue), have self-renewing potential and display significant plasticity. The stem cells are undifferentiated biological cells that can
differentiate into specialized cells and divide through mitosis to produce more stem cells. Human stem cells represent a subpopulation of tumor cells endowed with self-renewal and multilineage differentiation capacity and with an innate resistance to cytotoxic agents. The feature is a major clinical challenge to eradicate of the residual cancer cells in cancer patients. Human stem cells are defined by their tumor-propagating ability when transplanted into immune-compromised mice and by their capacity to fully recapitulate the original heterogeneity in all cancer cell types [20].
Like all stem cells, oncogenically transformed CSCs are defined by their ability for self-renewal and multipotency. The abnormal stem cells contributed to the development and recurrence of cancer. These tumorigenic
stem/progenitor cell populations are collectively named CSCs. It was explained the causes of cancer drug resistance and recurrence of cancer after curative resection. The CSC hypothesis states that, although it represent a rare population of cells within a tumor, their high tumorigenic capacity drives tumorigenesis [21].
Anticancer drugs kill cancer cells and cause a decrease in tumor mass.
Frequently, however, the cancer re-arises after a few months or even years because the therapy failed to kill all of the cancer stem cells. Future anticancer
therapies need to be tested for their efficacy in killing CSCs rather than the population of cancer cells. New generations of anticancer drugs will be developed to selectively and specifically find and destroy various different populations of CSCs [22, 23].
1.6 Cancer stem cell markers in common cancers
CSCs are cells within tumors that possess the capacity to self-renew and to generate the heterogeneous lineages of cancer cells that comprise the tumor.
First studies discovered that subpopulation of leukemic cells that express a specific surface marker CD34, but lack the CD38 marker [24]. It is the first conclusive evidence for cancer stem cells. Later studies discovered that other malignant tumors, such as cancers of the brain, breast, colon, ovary, pancreas and prostate, can also be composed of morphologically and phenotypically heterogeneous cell populations with varying self-renewal capacities, degrees of differentiation, and clonogenic and tumorigenic potentials [25]. In most cases, such cells have been identified through their expression of specific cell surface markers. For example, cancer stem cell markers frequently used to identify adult stem cells within the prostate, breast and intestine include CD44, CD133, ESA, CD69, p63, as well as some stem cell antigen, such as CD34, c-kit, fms related tyrosine kinase-3, neural cell adhesion molecule, and Thy-1 [26-28].
Also, the transcription factors Oct4, SOX2 and Nanog have been identified as main regulators that maintain the self-renewal of embryonic stem cells. They are overexpressed in many types of cancers and are associated with malignant progression and poor prognosis including NSCLC [29].
The study aims to find out if BJ of CHM inhibited to growth of cancer cells and the derived CSCs in a hope that a new generation of drugs be
developed against somatically mutated EGFR become of target therapy.