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Fulltext Association of SMAD4 loss with drug resistance in clinical cancer patients: A systematic meta-analysis

Xu W, Lee SH, Qiu F, Zhou L, Wang X, Ye T, et al.

PLoS One, 2021;16(5):e0250634.
PMID: 34048444 DOI: 10.1371/journal.pone.0250634

BACKGROUND: Drug resistance frequently led to the failure of chemotherapy for malignant cancers, hence causing cancer relapse. Thus, understanding mechanism of drug resistance in cancer is vital to improve the treatment efficacy. Here, we aim to evaluate the association between SMAD4 expression and the drug resistance in cancers by performing a meta-analysis.
METHOD: Relevant studies detecting SMAD4 expression in cancer patients treated with chemo-drugs up till December 2020 were systematically searched in four common scientific databases using selected keywords. The pooled hazard ratio (HR) was the ratio of hazard rate between SMAD4neg population vs SMAD4pos population. The HRs and risk ratios (RRs) with 95% confidence intervals (CIs) were used to explore the association between SMAD4 expression losses with drug resistance in cancers.
RESULT: After an initial screening according to the inclusion and exclusion criteria, eleven studies were included in the meta-analysis. There were a total of 2092 patients from all the included studies in this analysis. Results obtained indicated that loss of SMAD4 expression was significantly correlated with drug resistance with pooled HRs (95% CI) of 1.23 (1.01-1.45), metastasis with pooled RRs (95% CI) of 1.10 (0.97-1.25) and recurrence with pooled RRs (95% CI) of 1.32 (1.06-1.64). In the subgroup analysis, cancer type, drug type, sample size and antibody brand did not affect the significance of association between loss of SMAD4 expression and drug resistance. In addition, there was no evidence of publication bias as suggested by Begg's test.
CONCLUSION: Findings from our meta-analysis demonstrated that loss of SMAD4 expression was correlated with drug resistance, metastasis and recurrence. Therefore, SMAD4 expression could be potentially used as a molecular marker for cancer resistance.

Matched MeSH terms: Smad4 Protein/genetics; Smad4 Protein/metabolism*
Fulltext miR-524-5p of the primate-specific C19MC miRNA cluster targets TP53IPN1- and EMT-associated genes to regulate cellular reprogramming

Nguyen PNN, Choo KB, Huang CJ, Sugii S, Cheong SK, Kamarul T

Stem Cell Res Ther, 2017 09 29;8(1):214.
PMID: 28962647 DOI: 10.1186/s13287-017-0666-3

BACKGROUND: Introduction of the transcription factors Oct4, Sox2, Klf4, and c-Myc (OSKM) is able to 'reprogram' somatic cells to become induced pluripotent stem cells (iPSCs). Several microRNAs (miRNAs) are known to enhance reprogramming efficiency when co-expressed with the OSKM factors. The primate-specific chromosome 19 miRNA cluster (C19MC) is essential in primate reproduction, development, and differentiation. miR-524-5p, a C19MC member, is highly homologous to the reprogramming miR-520d-5p; we also reported that miR-524-5p was expressed in iPSCs but not mesenchymal stem cells (MSCs). This study aimed to elucidate possible contributions of miR-524-5p to the reprogramming process.
METHODS: A miR-524-5p precursor was introduced into human fibroblast HFF-1 in the presence of OSKM, and the relative number of embryonic stem cell (ESC)-like colonies that stained positively with alkaline phosphatase (AP) and Nanog were quantified to determine reprogramming efficiency. A miR-524-5p mimic was transfected to MSCs to investigate the effects of miR-524-5p on TP53INP1, ZEB2, and SMAD4 expression by real-time polymerase chain reaction (PCR) and Western blot. Direct gene targeting was confirmed by luciferase activity. A phylogenetic tree of TP53INP1 was constructed by the Clustal method. Contribution of miR-524-5p to cell proliferation and apoptosis was examined by cell counts, BrdU, MTT, and cell death assays, and pluripotency gene expression by real-time PCR.
RESULTS: Co-expressing the miR-524 precursor with OSKM resulted in a two-fold significant increase in the number of AP- and Nanog-positive ESC-like colonies, indicating a role for miR-524-5p in reprogramming. The putative target, TP53INP1, showed an inverse expression relationship with miR-524-5p; direct TP53INP1 targeting was confirmed in luciferase assays. miR-524-5p-induced TP53INP1 downregulation enhanced cell proliferation, suppressed apoptosis, and upregulated the expression of pluripotency genes, all of which are critical early events of the reprogramming process. Interestingly, the TP53INP1 gene may have co-evolved late with the primate-specific miR-524-5p. miR-524-5p also promoted mesenchymal-to-epithelial transition (MET), a required initial event of reprogramming, by directly targeting the epithelial-to-mesenchymal transition (EMT)-related genes, ZEB2 and SMAD4.
CONCLUSIONS: Via targeting TP53INP1, ZEB2, and SMAD4, miR-524-5p contributes to the early stage of inducing pluripotency by promoting cell proliferation, inhibiting apoptosis, upregulating expression of pluripotency genes, and enhancing MET. Other C19MC miRNAs may have similar reprogramming functions.

Matched MeSH terms: Smad4 Protein/genetics; Smad4 Protein/metabolism
Association of TGFβ1 and SMAD4 variants in the etiology of keloid scar in the Malay population

Emami A, Halim AS, Salahshourifar I, Yussof SJ, Khoo TL, Kannan TP

Arch. Dermatol. Res., 2012 Sep;304(7):541-7.
PMID: 22805880 DOI: 10.1007/s00403-012-1262-0

Keloid is a complex condition with environmental and genetic risk-contributing factors. Two candidate genes, TGFβ1 and SMAD4, located in the same signaling pathway are highly expressed in the keloid fibroblast cells. In a case-control design, TGFβ1 haplotypes showed association with the risk of keloid in the present study. The CC haplotype, composed of both c.29C>T and -509T>C variants, was observed more frequently among cases (Corrected p = 0.037, OR = 2.07, 95 % CI = 0.87-4.93), showing a 4.5-fold increased risk for keloid. The AG genotype of the SMAD4 c.5131A>G variant showed a trend of significance (p = 0.0573, OR = 1.75, 95 % CI = 0.99-3.13). Taken together, either of these variants is most probably causative at the expression level or is in linkage disequilibrium with other causative variants in a complex pattern together with the environmental factors that contribute to the condition. To the best of our knowledge, there is only one documented report on a relationship between TGFβ1 and keloid with no association within the Caucasian population, while there have not been any reports for SMAD4. Therefore, the present study is likely the first research showing a significant association between TGFβ1 variants and keloids in the Malay population.

Matched MeSH terms: Smad4 Protein/genetics*
Fulltext MicroRNA-362 negatively and positively regulates SMAD4 expression in TGF-β/SMAD signaling to suppress cell migration and invasion

Cheng HP, Huang CJ, Tsai ML, Ong HT, Cheong SK, Choo KB, et al.

Int J Med Sci, 2021;18(8):1798-1809.
PMID: 33746597 DOI: 10.7150/ijms.50871

Cell migration and invasion are modulated by epithelial-to-mesenchymal transition (EMT) and the reverse MET process. Despite the detection of microRNA-362 (miR-362, both the miR-362-5p and -3p species) in cancers, none of the identified miR-362 targets is a mesenchymal or epithelial factor to link miR-362 with EMT/MET and metastasis. Focusing on the TGF-β/SMAD signaling pathway in this work, luciferase assays and western blot data showed that miR-362 targeted and negatively regulated expression of SMAD4 and E-cadherin, but not SNAI1, which is regulated by SMAD4. However, miR-362 knockdown also down-regulated SMAD4 and SNAI1, but up-regulated E-cadherin expression. Wound-healing and transwell assays further showed that miR-362 knockdown suppressed cell migration and invasion, effects which were reversed by over-expressing SMAD4 or SNAI1, or by knocking down E-cadherin in the miR-362 knockdown cells. In orthotopic mice, miR-362 knockdown inhibited metastasis, and displayed the same SMAD4 and E-cadherin expression profiles in the tumors as in the in vitro studies. A scheme is proposed to integrate miR-362 negative regulation via SMAD4, and to explain miR-362 positive regulation of SMAD4 via miR-362 targeting of known SMAD4 suppressors, BRK and DACH1, which would have resulted in SMAD4 depletion and annulment of subsequent involvement in TGF-β signaling actions. Hence, miR-362 both negatively and positively regulates SMAD4 expression in TGF-β/SMAD signaling pathway to suppress cell motility and invasiveness and metastasis, and may explain the reported clinical association of anti-miR-362 with suppressed metastasis in various cancers. MiR-362 knockdown in miR-362-positive cancer cells may be used as a therapeutic strategy to suppress metastasis.

Matched MeSH terms: Smad4 Protein/genetics*; Smad4 Protein/metabolism
Fulltext Down-Regulation of MicroRNA-210 Confers Sensitivity towards 1'S-1'-Acetoxychavicol Acetate (ACA) in Cervical Cancer Cells by Targeting SMAD4

Phuah NH, Azmi MN, Awang K, Nagoor NH

Mol Cells, 2017 Apr;40(4):291-298.
PMID: 28401751 DOI: 10.14348/molcells.2017.2285

MicroRNAs (miRNAs) are short non-coding RNAs that regulate genes posttranscriptionally. Past studies have reported that miR-210 is up-regulated in many cancers including cervical cancer, and plays a pleiotropic role in carcinogenesis. However, its role in regulating response towards anti-cancer agents has not been fully elucidated. We have previously reported that the natural compound 1'S-1'-acetoxychavicol acetate (ACA) is able to induce cytotoxicity in various cancer cells including cervical cancer cells. Hence, this study aims to investigate the mechanistic role of miR-210 in regulating response towards ACA in cervical cancer cells. In the present study, we found that ACA down-regulated miR-210 expression in cervical cancer cells, and suppression of miR-210 expression enhanced sensitivity towards ACA by inhibiting cell proliferation and promoting apoptosis. Western blot analysis showed increased expression of mothers against decapentaplegic homolog 4 (SMAD4), which was predicted as a target of miR-210 by target prediction programs, following treatment with ACA. Luciferase reporter assay confirmed that miR-210 binds to sequences in 3'UTR of SMAD4. Furthermore, decreased in SMAD4 protein expression was observed when miR-210 was overexpressed. Conversely, SMAD4 protein expression increased when miR-210 expression was suppressed. Lastly, we demonstrated that overexpression of SMAD4 augmented the anti-proliferative and apoptosis-inducing effects of ACA. Taken together, our results demonstrated that down-regulation of miR-210 conferred sensitivity towards ACA in cervical cancer cells by targeting SMAD4. These findings suggest that combination of miRNAs and natural compounds could provide new strategies in treating cervical cancer.

Matched MeSH terms: Smad4 Protein/genetics; Smad4 Protein/metabolism*
The role of TGFbeta in human cancers

Wong SF, Lai LC

Pathology, 2001 Feb;33(1):85-92.
PMID: 11280615

Transforming growth factor beta (TGFbeta) is secreted as a large latent precursor from both normal and transformed cells which needs to be activated for biological activity. The active TGFbeta binds either directly to TbetaR-II or indirectly by binding to beta-glycan which then presents the TGFbeta to TbetaR-II. Formation of the TGFbeta-TbetaR-II complex rapidly leads to phosphorylation of TbetaR-I. TbetaR-I, in turn, phosphorylates receptor-specific Smads and induces their translocation into the nucleus. TGFbeta is able to act as a growth stimulator or inhibitor and elicits a broad spectrum of biological effects on various cell types. However, these cells may lose their sensitivity and responsiveness to TGFbeta. Down-regulation or loss of functional receptors, aberrant signal transduction pathways due to Smad mutations, loss of the cell's ability to activate latent TGFbeta, loss of the peptide itself or functional genes that control the transcription and translation of TGFbeta may contribute to development of cancer.

Matched MeSH terms: Smad4 Protein