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Strychnan and secoangustilobine A type alkaloids from Alstonia spatulata. Revision of the C-20 configuration of scholaricine

Tan SJ, Low YY, Choo YM, Abdullah Z, Etoh T, Hayashi M, et al.

J Nat Prod, 2010 Nov 29;73(11):1891-7.
PMID: 21043460 DOI: 10.1021/np100552b

A total of 25 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia spatulata, of which five are new alkaloids of the strychnan type (alstolucines A-E, 1-5) and the other, a new alkaloid of the secoangustilobine A type (alstolobine A, 6). The structures of these alkaloids were established using NMR and MS analysis and, in the case of alstolucine B (2), also confirmed by X-ray diffraction analysis. A reinvestigation of the stereochemical assignment of scholaricine (13) by NMR and X-ray analyses indicated that the configuration at C-20 required revision. Alkaloids 1, 2, 6, 7, 9, 10, and 13 reversed multidrug resistance in vincristine-resistant KB cells.

Matched MeSH terms: Drug Resistance, Neoplasm/drug effects
Strategies and validation for siRNA-based therapeutics for the reversal of multi-drug resistance in cancer

Fatemian T, Othman I, Chowdhury EH

Drug Discov Today, 2014 Jan;19(1):71-8.
PMID: 23974068 DOI: 10.1016/j.drudis.2013.08.007

Resistance of cancer cells to anticancer drugs is the main reason for the failure of traditional cancer treatments. Various cellular components and different loops within the signaling pathways contribute to drug resistance which could be modulated with the aim to restore drug efficacy. Unveiling the molecular mechanisms for cancer drug resistance has now paved the way for the development of novel approaches to regulate the response rates to anticancer drugs at the genetic level. The recent progress on identification and validation of the vital genes directly or indirectly involved in development of cancer drug resistance with the aid of the specific knock down ability of RNA interference technology is discussed in this review.

Matched MeSH terms: Drug Resistance, Neoplasm*
Fulltext Small Cell Transformation and T790M Mutation as Coresistance Mechanisms for First-line Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitor (TKI) Therapy Failure

Shee-Chai C, Liam CK, Mun KS

J Thorac Oncol, 2017 10;12(10):e171-e173.
PMID: 28939153 DOI: 10.1016/j.jtho.2017.06.068
Matched MeSH terms: Drug Resistance, Neoplasm/genetics
Silencing of suppressor of cytokine signaling-3 due to methylation results in phosphorylation of STAT3 in imatinib resistant BCR-ABL positive chronic myeloid leukemia cells

Al-Jamal HA, Jusoh SA, Yong AC, Asan JM, Hassan R, Johan MF

Asian Pac J Cancer Prev, 2014;15(11):4555-61.
PMID: 24969884

BACKGROUND: Silencing due to methylation of suppressor of cytokine signaling-3 (SOCS-3), a negative regulator gene for the JAK/STAT signaling pathway has been reported to play important roles in leukemogenesis. Imatinib mesylate is a tyrosine kinase inhibitor that specifically targets the BCR-ABL protein and induces hematological remission in patients with chronic myeloid leukemia (CML). Unfortunately, the majority of CML patients treated with imatinib develop resistance under prolonged therapy. We here investigated the methylation profile of SOCS-3 gene and its downstream effects in a BCR-ABL positive CML cells resistant to imatinib.
MATERIALS AND METHODS: BCR-ABL positive CML cells resistant to imatinib (K562-R) were developed by overexposure of K562 cell lines to the drug. Cytotoxicity was determined by MTS assays and IC50 values calculated. Apoptosis assays were performed using annexin V-FITC binding assays and analyzed by flow cytometry. Methylation profiles were investigated using methylation specific PCR and sequencing analysis of SOCS-1 and SOCS-3 genes. Gene expression was assessed by quantitative real-time PCR, and protein expression and phosphorylation of STAT1, 2 and 3 were examined by Western blotting.
RESULTS: The IC50 for imatinib on K562 was 362 nM compared to 3,952 nM for K562-R (p=0.001). Percentage of apoptotic cells in K562 increased upto 50% by increasing the concentration of imatinib, in contrast to only 20% in K562-R (p<0.001). A change from non-methylation of the SOCS-3 gene in K562 to complete methylation in K562-R was observed. Gene expression revealed down- regulation of both SOCS-1 and SOCS-3 genes in resistant cells. STAT3 was phosphorylated in K562-R but not K562.
CONCLUSIONS: Development of cells resistant to imatinib is feasible by overexposure of the drug to the cells. Activation of STAT3 protein leads to uncontrolled cell proliferation in imatinib resistant BCR-ABL due to DNA methylation of the SOCS-3 gene. Thus SOCS-3 provides a suitable candidate for mechanisms underlying the development of imatinib resistant in CML patients.

Matched MeSH terms: Drug Resistance, Neoplasm/genetics
Silencing of ZFP36L2 increases sensitivity to temozolomide through G2/M cell cycle arrest and BAX mediated apoptosis in GBM cells

Che Mat MF, Mohamad Hanif EA, Abdul Murad NA, Ibrahim K, Harun R, Jamal R

Mol Biol Rep, 2021 Feb;48(2):1493-1503.
PMID: 33590411 DOI: 10.1007/s11033-021-06144-z

Despite the advancements in primary brain tumour diagnoses and treatments, the mortality rate remains high, particularly in glioblastoma (GBM). Chemoresistance, predominantly in recurrent cases, results in decreased mean survival of patients with GBM. We aimed to determine the chemosensitisation and oncogenic characteristics of zinc finger protein 36-like 2 (ZFP36L2) in LN18 GBM cells via RNA interference (RNAi) delivery. We conducted a meta-analysis of microarray datasets and RNAi screening using pooled small interference RNA (siRNA) to identify the druggable genes responsive to GBM chemosensitivity. Temozolomide-resistant LN18 cells were used to evaluate the effects of gene silencing on chemosensitisation to the sub-lethal dose (1/10 of the median inhibitory concentration [IC50]) of temozolomide. ZFP36L2 protein expression was detected by western blotting. Cell viability, proliferation, cell cycle and apoptosis assays were carried out using commercial kits. A human apoptosis array kit was used to determine the apoptosis pathway underlying chemosensitisation by siRNA against ZFP36L2 (siZFP36L2). Statistical analyses were performed using one-way analysis of variance; p > 0.05 was considered significant. The meta-analysis and RNAi screening identified ZFP36L2 as a potential marker of GBM. ZFP36L2 knockdown significantly induced apoptosis (p

Matched MeSH terms: Drug Resistance, Neoplasm/genetics
Secondary B-cell acute lymphoblastic leukemia following Wilms' tumor: clinical and in vitro chemosensitivity studies

Ariffin H, Muthukkumaran T, Stanslas J, Sabariah AR, Veerasekaran N, Lin HP

Leuk Lymphoma, 2005 Aug;46(8):1233-7.
PMID: 16085568

We report the clinical features and in vitro chemosensitivity assay findings of a 13-year-old girl who developed secondary B-cell acute lymphoblastic leukemia (ALL) 7 years after a diagnosis of Wilms' tumor. The patient was treated using the Berlin - Frankfurt - Muenster (BFM) ALL chemotherapy protocol with poor response to initial therapy before succumbing to sepsis. An in vitro chemosensitivity assay on her peripheral blood lymphoblasts was performed while she was undergoing induction therapy and showed a high level of resistance to drugs commonly used for ALL therapy, e.g. steroids, anthracyclines, vincristine and L-asparaginase. The mechanism of chemoresistance was not elicited, but was probably not related to P-glycoprotein (P-gp) over-expression. We believe that the in vitro chemosensitivity assay is a good indicator of cellular response to chemotherapy and may provide reliable information for the basis of the selection of drugs to be used for the treatment of similarly rare patients rather than relying on "standard" protocols.

Matched MeSH terms: Drug Resistance, Neoplasm
SRJ09, a promising anticancer drug lead: Elucidation of mechanisms of antiproliferative and apoptogenic effects and assessment of in vivo antitumor efficacy

Wong CC, Lim SH, Sagineedu SR, Lajis NH, Stanslas J

Pharmacol Res, 2016 05;107:66-78.
PMID: 26940565 DOI: 10.1016/j.phrs.2016.02.024

SRJ09 (3,19-(2-bromobenzylidene)andrographolide), a semisynthetic andrographolide (AGP) derivative, was shown to induce G1 cell cycle arrest and eventually apoptosis in breast and colon cancer cell lines. The present investigation was carried out to elucidate the mechanisms cell cycle arrest and apoptosis and evaluate the in vivo antitumor activity of SRJ09. The in vitro growth inhibitory properties of compounds were assessed in colon (HCT-116) and breast (MCF-7) cancer cell lines. Immunoblotting was utilized to quantitate the protein levels in cells. The gene expressions were determined using reverse transcriptase PCR (RT-PCR). Pharmacokinetic investigation was carried out by determining SRJ09 levels in plasma of Balb/C mice using HPLC. In vivo antitumor activity was evaluated in athymic mice carrying HCT-116 colon tumor xenografts. SRJ09 displayed improved in vitro activity when compared with AGP by producing rapid cell killing effect in vitro. Its activity was not compromised in MES-SA/Dx5 multidrug resistant (MDR) cells expressing p-glycoprotein. Cells treated with SRJ09 (0.1-10μM) displayed increased p21 protein level, which corresponded with gene expression. Whereas CDK4 protein level and gene expression was suppressed. The treatment did not affect cyclin D1. Changes of these proteins paralleled G1 cell cycle arrest in both cell lines as determined by flow cytometry. Induction of apoptosis by SRJ09 in HCT-116 cells which occurred independent of p53 and bcl-2 was inhibited in the presence of caspase 8 inhibitor, implicating the extrinsic apoptotic pathway. A single dose (100mg/kg, i.p) of SRJ09 produced a plasma concentration range of 12-30.4μM. At 400mg/kg (q4dX3), it significantly retarded growth of tumor xenografts. The antitumor activity of SRJ09 is suggested mediated via the induction of p21 expression and suppression of CDK-4 expression without affecting cyclin D1 to trigger G1 arrest leading to apoptosis.

Matched MeSH terms: Drug Resistance, Neoplasm
Role of therapeutic agents on repolarisation of tumour-associated macrophage to halt lung cancer progression

Aldawsari HM, Gorain B, Alhakamy NA, Md S

J Drug Target, 2020 02;28(2):166-175.
PMID: 31339380 DOI: 10.1080/1061186X.2019.1648478

Tumour-associated macrophages (TAMs) represent as much as 50% of the solid mass in different types of human solid tumours including lung, breast, ovarian and pancreatic adenocarcinomas. The tumour microenvironment (TME) plays an important role in the polarisation of macrophages into the M1 phenotype, which is tumour-suppressive, or M2 phenotype, which is tumour promoting. Preclinical and clinical evidences suggest that TAMs are predominantly of the M2 phenotype that supports immune suppression, tumour growth, angiogenesis, metastasis and therapeutic resistance. Hence, significant attention has been focussed on the development of strategies for the modification of TAMs to halt lung cancer progression. The promotion of repolarisation from the M2 to the M1 subtype, or the prevention of M2 polarisation of TAMs in the stromal environment is potential approaches to reduce progression and metastasis of lung cancer. The focus of this article is an introduction to the development and evaluation of therapeutic agents that may halt lung cancer progression via the manipulation of macrophage polarisation. This article will address recent advances in the therapeutic efficacy of nanomedicine exploiting surface functionalisation of nanoparticles and will also consider future perspectives.

Matched MeSH terms: Drug Resistance, Neoplasm
Rising horizon in circumventing multidrug resistance in chemotherapy with nanotechnology

Choudhury H, Pandey M, Yin TH, Kaur T, Jia GW, Tan SQL, et al.

Mater Sci Eng C Mater Biol Appl, 2019 Aug;101:596-613.
PMID: 31029353 DOI: 10.1016/j.msec.2019.04.005

Multidrug resistance (MDR) is one of the key barriers in chemotherapy, leading to the generation of insensitive cancer cells towards administered therapy. Genetic and epigenetic alterations of the cells are the consequences of MDR, resulted in drug resistivity, which reflects in impaired delivery of cytotoxic agents to the cancer site. Nanotechnology-based nanocarriers have shown immense shreds of evidence in overcoming these problems, where these promising tools handle desired dosage load of hydrophobic chemotherapeutics to facilitate designing of safe, controlled and effective delivery to specifically at tumor microenvironment. Therefore, encapsulating drugs within the nano-architecture have shown to enhance solubility, bioavailability, drug targeting, where co-administered P-gp inhibitors have additionally combat against developed MDR. Moreover, recent advancement in the stimuli-sensitive delivery of nanocarriers facilitates a tumor-targeted release of the chemotherapeutics to reduce the associated toxicities of chemotherapeutic agents in normal cells. The present article is focused on MDR development strategies in the cancer cell and different nanocarrier-based approaches in circumventing this hurdle to establish an effective therapy against deadliest cancer disease.

Matched MeSH terms: Drug Resistance, Neoplasm
Rhazinilam-Leuconolam-Leuconoxine Alkaloids from Leuconotis griffithii

Gan CY, Low YY, Thomas NF, Kam TS

J Nat Prod, 2013 May 24;76(5):957-64.
PMID: 23647487 DOI: 10.1021/np400214y

Eight new indole alkaloids (1-8) belonging to the rhazinilam-leuconolam-leuconoxine group, in addition to 52 other alkaloids, were isolated from the stem-bark extract of Leuconotis griffithii, viz., nor-rhazinicine (1), 5,21-dihydrorhazinilam-N-oxide (2), 3,14-dehydroleuconolam (3), and leuconodines A-E (4-8). The structures of these alkaloids were determined using NMR and MS analyses and in some instances confirmed by X-ray diffraction analyses. Alkaloids 1, 5, and 7 showed only moderate to weak cytotoxicity toward KB cells (IC50 12-18 μg/mL), while 8 showed moderate activity in reversing MDR in vincristine-resistant KB cells.

Matched MeSH terms: Drug Resistance, Neoplasm/drug effects
Fulltext Reversing multidrug resistance in breast cancer cells by silencing ABC transporter genes with nanoparticle-facilitated delivery of target siRNAs

Li YT, Chua MJ, Kunnath AP, Chowdhury EH

Int J Nanomedicine, 2012;7:2473-81.
PMID: 22701315 DOI: 10.2147/IJN.S30500

Multidrug resistance, a major impediment to successful cancer chemotherapy, is the result of overexpression of ATP-binding cassette (ABC) transporters extruding internalized drugs. Silencing of ABC transporter gene expression with small interfering RNA (siRNA) could be an attractive approach to overcome multidrug resistance of cancer, although delivery of siRNA remains a major hurdle to fully exploit the potential of siRNA-based therapeutics. Recently, we have developed pH-sensitive carbonate apatite nanoparticles to efficiently carry and transport siRNA across the cell membrane, enabling knockdown of the cyclin B1 gene and consequential induction of apoptosis in synergy with anti-cancer drugs.

Matched MeSH terms: Drug Resistance, Neoplasm
Reversal of multidrug resistance (MDR) by aspidofractinine-type indole alkaloids

Kam TS, Subramaniam G, Sim KM, Yoganathan K, Koyano T, Toyoshima M, et al.

Bioorg Med Chem Lett, 1998 Oct 06;8(19):2769-72.
PMID: 9873619

A series of indole alkaloids of the aspidofractinine-type was assessed for their potential in reversing MDR in vincristine-resistant KB cells. Of the compounds tested, kopsiflorine, kopsamine, pleiocarpine, 11-methoxykopsilongine, lahadinine A and N-methoxycarbonyl-11,12-methylenedioxy-delta 16,17-kopsinine were found to show appreciable activity.

Matched MeSH terms: Drug Resistance, Neoplasm
Fulltext Ravulizumab (ALXN1210) vs eculizumab in adult patients with PNH naive to complement inhibitors: the 301 study

Lee JW, Sicre de Fontbrune F, Wong Lee Lee L, Pessoa V, Gualandro S, Füreder W, et al.

Blood, 2019 02 07;133(6):530-539.
PMID: 30510080 DOI: 10.1182/blood-2018-09-876136

Ravulizumab (ALXN1210), a new complement C5 inhibitor, provides immediate, complete, and sustained C5 inhibition. This phase 3, open-label study assessed the noninferiority of ravulizumab to eculizumab in complement inhibitor-naive adults with paroxysmal nocturnal hemoglobinuria (PNH). Patients with lactate dehydrogenase (LDH) ≥1.5 times the upper limit of normal and at least 1 PNH symptom were randomized 1:1 to receive ravulizumab or eculizumab for 183 days (N = 246). Coprimary efficacy end points were proportion of patients remaining transfusion-free and LDH normalization. Secondary end points were percent change from baseline in LDH, change from baseline in Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue score, proportion of patients with breakthrough hemolysis, stabilized hemoglobin, and change in serum free C5. Ravulizumab was noninferior to eculizumab for both coprimary and all key secondary end points (Pinf < .0001): transfusion avoidance (73.6% vs 66.1%; difference of 6.8% [95% confidence interval (CI), -4.66, 18.14]), LDH normalization (53.6% vs 49.4%; odds ratio, 1.19 [0.80, 1.77]), percent reduction in LDH (-76.8% vs -76.0%; difference [95% CI], -0.83% [-5.21, 3.56]), change in FACIT-Fatigue score (7.07 vs 6.40; difference [95% CI], 0.67 [-1.21, 2.55]), breakthrough hemolysis (4.0% vs 10.7%; difference [95% CI], -6.7% [-14.21, 0.18]), and stabilized hemoglobin (68.0% vs 64.5%; difference [95% CI], 2.9 [-8.80, 14.64]). The safety and tolerability of ravulizumab and eculizumab were similar; no meningococcal infections occurred. In conclusion, ravulizumab given every 8 weeks achieved noninferiority compared with eculizumab given every 2 weeks for all efficacy end points, with a similar safety profile. This trial was registered at www.clinicaltrials.gov as #NCT02946463.

Matched MeSH terms: Drug Resistance, Neoplasm/drug effects*
Fulltext Proteomic time course of breast cancer cells highlights enhanced sensitivity to Stat3 and Src inhibitors prior to endocrine resistance development

Madden SF, Cremona M, Farrelly AM, Low WH, McBryan J

Cancer Gene Ther, 2023 Feb;30(2):324-334.
PMID: 36266450 DOI: 10.1038/s41417-022-00548-0

To prevent the development of endocrine-resistant breast cancer, additional targeted therapies are increasingly being trialled in combination with endocrine therapy. The molecular mechanisms facilitating cancer cell survival during endocrine treatment remain unknown but could help direct selection of additional targeted therapies. We present a novel proteomic timecourse dataset, profiling potential drug targets in a population of MCF7 cells during 1 year of tamoxifen treatment. Reverse phase protein arrays profiled >70 proteins across 30 timepoints. A biphasic response to tamoxifen was evident, which coincided with changes in growth rate. Tamoxifen strongly impeded cell growth for the first 160 days, followed by gradual growth recovery and eventual resistance development. The growth-impeded phase was distinguished by the phosphorylation of Stat3 (y705) and Src (y527). Tumour tissue from patients treated with neo-adjuvant endocrine therapy (<4 months) also displayed increased Stat3 and Src signalling. Inhibitors of Stat3 (napabucasin) and Src (dasatinib), were effective at killing tamoxifen-treated MCF7 and T47D cells. Sensitivity to both drugs was significantly enhanced once tamoxifen had induced the growth-impeded phase. This novel proteomic resource identifies key mechanisms enabling cell survival during tamoxifen treatment. It provides valuable insight into potential drug combinations and timing that may prevent the development of endocrine resistance.

Matched MeSH terms: Drug Resistance, Neoplasm
Prevalence of BCR-ABL T315I Mutation in Malaysian Patients with Imatinib-Resistant Chronic Myeloid Leukemia

Mat Yusoff Y, Abu Seman Z, Othman N, Kamaluddin NR, Esa E, Zulkiply NA, et al.

Asian Pac J Cancer Prev, 2018 Dec 25;19(12):3317-3320.
PMID: 30583336

Objective: Chronic Myeloid Leukemia (CML) is caused by a reciprocal translocation between chromosomes 9
and 22, t(9;22) (q34;q11) which encodes for the BCR-ABL fusion protein. Discovery of Imatinib Mesylate (IM) as
first line therapy has brought tremendous improvement in the management of CML. However, emergence of point
mutations within the BCR-ABL gene particularly T315I mutation, affects a common BCR-ABL kinase contact residue
which impairs drug binding thus contribute to treatment resistance. This study aims to investigate the BCR-ABL T315I
mutation in Malaysian patients with CML. Methods: A total of 285 patients diagnosed with CML were included in this
study. Mutation detection was performed using qualitative real-time PCR (qPCR). Results: Fifteen out of 285 samples
(5.26%) were positive for T315I mutations after amplification with real-time PCR assay. From the total number of
positive samples, six patients were in accelerated phase (AP), four in chronic phase (CP) and five in blast crisis (BC).
Conclusion: Mutation testing is recommended for choosing various tyrosine kinase inhibitors (TKIs) to optimize
outcomes for both cases of treatment failure or suboptimal response to imatinib. Therefore, detection of T315I mutation
in CML patients are clinically useful in the selection of appropriate treatment strategies to prevent disease progression.

Matched MeSH terms: Drug Resistance, Neoplasm/genetics*
Pharmacogenetics and the treatment of chronic myeloid leukemia: how relevant clinically? An update

Ankathil R, Azlan H, Dzarr AA, Baba AA

Pharmacogenomics, 2018 04;19(5):475-393.
PMID: 29569526 DOI: 10.2217/pgs-2017-0193

Despite the excellent efficacy and improved clinical responses obtained with imatinib mesylate (IM), development of resistance in a significant proportion of chronic myeloid leukemia (CML) patients on IM therapy have emerged as a challenging problem in clinical practice. Resistance to imatinib can be due to heterogeneous array of factors involving BCR/ABL-dependent and BCR/ABL-independent pathways. Although BCR/ABL mutation is the major contributory factor for IM resistance, reduced bio-availability of IM in leukemic cells is also an important pharmacokinetic factor that contributes to development of resistance to IM in CML patients. The contribution of polymorphisms of the pharmacogenes in relation to IM disposition and treatment outcomes have been studied by various research groups in numerous population cohorts. However, the conclusions arising from these studies have been highly inconsistent. This review encompasses an updated insight into the impact of pharmacogenetic variability on treatment response of IM in CML patients.

Matched MeSH terms: Drug Resistance, Neoplasm/genetics
Fulltext Pathological transition as the arising mechanism for drug resistance in lung cancer

Chen Y, Tang WY, Tong X, Ji H

Cancer Commun (Lond), 2019 10 01;39(1):53.
PMID: 31570104 DOI: 10.1186/s40880-019-0402-8

Despite the tremendous efforts for improving therapeutics of lung cancer patients, its prognosis remains disappointing. This can be largely attributed to the lack of comprehensive understanding of drug resistance leading to insufficient development of effective therapeutics in clinic. Based on the current progresses of lung cancer research, we classify drug resistance mechanisms into three different levels: molecular, cellular and pathological level. All these three levels have significantly contributed to the acquisition and evolution of drug resistance in clinic. Our understanding on drug resistance mechanisms has begun to change the way of clinical practice and improve patient prognosis. In this review, we focus on discussing the pathological changes linking to drug resistance as this has been largely overlooked in the past decades.

Matched MeSH terms: Drug Resistance, Neoplasm*
Parallel genome-wide RNAi screens identify lymphocyte-specific protein tyrosine kinase (LCK) as a targetable vulnerability of cell proliferation and chemoresistance in nasopharyngeal carcinoma

Liew K, Yu GQS, Wei Pua LJ, Wong LZ, Tham SY, Hii LW, et al.

Cancer Lett, 2021 Apr 28;504:81-90.
PMID: 33587980 DOI: 10.1016/j.canlet.2021.02.006

Despite recent in advances in the management of nasopharyngeal carcinoma (NPC), development of targeted therapy remains challenging particularly in patients with recurrent or metastatic disease. To search for clinically relevant targets for the treatment of NPC, we carried out parallel genome-wide functional screens to identified essential genes that are required for NPC cells proliferation and cisplatin resistance. We identified lymphocyte-specific protein tyrosine kinase (LCK) as a key vulnerability of both proliferation and cisplatin resistance. Depletion of endogenous LCK or treatment of cells with LCK inhibitor induced tumor-specific cell death and synergized cisplatin sensitivity in EBV-positive C666-1 and EBV-negative SUNE1 cells. Further analyses demonstrated that LCK is regulating the proliferation and cisplatin resistance through activation of signal transducer and activator of transcription 5 (STAT5). Taken together, our study provides a molecular basis for targeting LCK and STAT5 signaling as potential druggable targets for the management of NPC.

Matched MeSH terms: Drug Resistance, Neoplasm/genetics*
PNMA2 mediates heterodimeric interactions and antagonizes chemo-sensitizing activities mediated by members of PNMA family

Lee YH, Pang SW, Tan KO

Biochem Biophys Res Commun, 2016 Apr 22;473(1):224-229.
PMID: 27003254 DOI: 10.1016/j.bbrc.2016.03.083

PNMA2, a member of the Paraneoplastic Ma Family (PNMA), was identified through expression cloning by using anti-sera from patients with paraneoplastic disorder. Tissue expression studies showed that PNMA2 was predominantly expressed in normal human brain; however, the protein was shown to exhibit abnormal expression profile as it was found to be expressed in a number of tumour tissues obtained from paraneopalstic patients. The abnormal expression profile of PNMA2 suggests that it might play an important role in tumorigenesis; however, apart from protein expression and immunological studies, the physiological role of PNMA2 remains unclear. In order to determine potential role of PNMA2 in tumorigenesis, and its functional relationship with PNMA family members, MOAP-1 (PNMA4) and PNMA1, expression constructs encoding the respective proteins were generated for both in vitro and in vivo studies. Our investigations showed that over-expressed MOAP-1 and PNMA1 promoted apoptosis and chemo-sensitization in MCF-7 cells as evidenced by condensed nuclei and Annexin-V positive MCF-7 cells; however, the effects mediated by these proteins were significantly inhibited or abolished when co-expressed with PNMA2 in MCF-7 cells. Furthermore, co-immunoprecipitation study showed that PNMA1 and MOAP-1 failed to associate with each other but readily formed respective heterodimer with PNMA2, suggesting that PNMA2 functions as antagonist of MOAP-1 and PNMA1 through heterodimeric interaction.

Matched MeSH terms: Drug Resistance, Neoplasm*
Overview of the multifaceted resistances toward EGFR-TKIs and new chemotherapeutic strategies in non-small cell lung cancer

Dzul Keflee R, Leong KH, Ogawa S, Bignon J, Chan MC, Kong KW

Biochem Pharmacol, 2022 Nov;205:115262.
PMID: 36191627 DOI: 10.1016/j.bcp.2022.115262

The role of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) has been vastly studied over the last decade. This has led to the rapid development of many generations of EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, patients treated with third-generation TKIs (osimertinib, avitinib and rociletinib) targeting the EGFR T790M mutation have shown emerging resistances and relapses. Therefore, further molecular understanding of NSCLC mutations, bypass signalling, tumour microenvironment and the existence of cancer stem cells to overcome such resistances is warranted. This will pave the way for designing novel and effective chemotherapies to improve patients' overall survival. In this review, we provide an overview of the multifaceted mechanisms of resistance towards EGFR-TKIs, as well as the challenges and perspectives that should be addressed in strategising chemotherapeutic treatments to overcome the ever-evolving and adaptive nature of NSCLC.

Matched MeSH terms: Drug Resistance, Neoplasm

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