SMAD4 Levels and Response to 5-Fluorouracil in Colorectal Cancer

Alhopuro, Pia; Alazzouzi, Hafid; Sammalkorpi, Heli; Dávalos, Verónica; Salovaara, Reijo; Hemminki, Akseli; Järvinen, Heikki; Mecklin∥, Jukka–Pekka; Schwartz, Simó; Aaltonen, Lauri A.; Arango, Diego

doi:10.1158/1078-0432.ccr-05-0244

Cited by 90 publications

(84 citation statements)

References 39 publications

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“…One of the proposed mechanisms is through the induction of epithelial-mesenchymal transition by TGF␤ (11). In addition, loss or inactivation of Smad4 has been shown to be a predictive marker for resistance to 5-FU-based chemotherapy in colorectal cancer (46,47). TGF␤ activates non-canonical signaling (i.e.…”

Section: Discussionmentioning

confidence: 99%

Transforming Growth Factor β Mediates Drug Resistance by Regulating the Expression of Pyruvate Dehydrogenase Kinase 4 in Colorectal Cancer

Zhang¹,

Zhang

Geng³

et al. 2016

Journal of Biological Chemistry

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Drug resistance is one of the main causes of colon cancer recurrence. However, our understanding of the underlying mechanisms and availability of therapeutic options remains limited. Here we show that expression of pyruvate dehydrogenase kinase 4 (PDK4) is positively correlated with drug resistance of colon cancer cells and induced by 5-fluorouracil (5-FU) treatment in drug-resistant but not drug-sensitive cells. Knockdown of PDK4 expression sensitizes colon cancer cells to 5-FU or oxaliplatin-induced apoptosis in vitro and increases the effectiveness of 5-FU in the inhibition of tumor growth in a mouse xenograft model in vivo. In addition, we demonstrate for the first time that TGF␤ mediates drug resistance by regulating PDK4 expression and that 5-FU induces PDK4 expression in a TGF␤ signaling-dependent manner. Mechanistically, knockdown or inhibition of PDK4 significantly increases the inhibitory effect of 5-FU on expression of the anti-apoptotic factors Bcl-2 and survivin. Importantly, studies of patient samples indicate that expression of PDK4 and phosphorylation of Smad2, an indicator of TGF␤ pathway activation, show a strong correlation and that both positively associate with chemoresistance in colorectal cancer. These findings indicate that the TGF␤/PDK4 signaling axis plays an important role in the response of colorectal cancer to chemotherapy. A major implication of our studies is that inhibition of PDK4 may have considerable therapeutic potential to overcome drug resistance in colorectal cancer patients, which warrants the development of PDK4-specific inhibitors.Colorectal cancer is the third most common cancer diagnosed and the second leading cause of cancer mortality in the United States. In addition to surgery, treatment for colorectal cancer patients, especially for patients with advanced disease, primarily relies on chemotherapy and radiation therapy. 5 is one of the most commonly used chemotherapeutic agents for colorectal cancer treatment. It induces cell cycle arrest and apoptosis in cancer cells (1). Although adjuvant 5-FU treatment has a good success rate, the high recurrence is still a major hurdle of treating colorectal cancer because of the resistance to chemotherapeutic drugs. Therefore, it is important to understand the mechanisms of drug resistance and identify new targets to increase the effectiveness of chemotherapy in colorectal cancer. TGF␤ plays an important role in cancer development and progression. Upon ligand binding, TGF␤ type II receptor (RII) recruits and activates TGF␤ type I receptor (RI), which then activates Smad2 and Smad3. Activated Smad2 and Smad3 form complexes with Smad4 and translocate to the nucleus, where they regulate gene expression (2). We and others have demonstrated that TGF␤ suppresses tumorigenicity in a variety of cancers, including colorectal cancer, and that loss of TGF␤ signaling leads to malignancy (3-6). Although many studies have shown that TGF␤ promotes metastasis (7), others have demonstrated that TGF␤ suppresses metastasis (8,9). Recently, studi...

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Section: Discussionmentioning

confidence: 99%

Transforming Growth Factor β Mediates Drug Resistance by Regulating the Expression of Pyruvate Dehydrogenase Kinase 4 in Colorectal Cancer

Zhang¹,

Zhang

Geng³

et al. 2016

Journal of Biological Chemistry

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“…RNA levels were measured by using Taqman assay Hs00224610 m1 in a GeneAmp 7500 sequence detection system (Applied Biosystems) as described in ref. 39. Expression of beta-actin served as a control.…”

Section: Methodsmentioning

confidence: 99%

“…Immunohistochemistry was performed as described in ref. 39, using two different anti-MYH11 antibodies (Chemicon International Sigma). Paraffin-embedded sections from 28 MSI and 39 MSS CRCs were immunostained.…”

Section: Methodsmentioning

confidence: 99%

Unregulated smooth-muscle myosin in human intestinal neoplasia

Alhopuro¹,

Phichith

Tuupanen³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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A recent study described a recessive ATPase activating germ-line mutation in smooth-muscle myosin (smmhc/myh11) underlying the zebrafish meltdown (mlt) phenotype. The mlt zebrafish develops intestinal abnormalities reminiscent of human Peutz-Jeghers syndrome (PJS) and juvenile polyposis (JP). To examine the role of MYH11 in human intestinal neoplasia, we searched for MYH11 mutations in patients with colorectal cancer (CRC), PJS and JP. We found somatic protein-elongating frameshift mutations in 55% of CRCs displaying microsatellite instability and in the germ-line of one individual with PJS. Additionally, two somatic missense mutations were found in one microsatellite stable CRC. These two missense mutations, R501L and K1044N, and the frameshift mutations were functionally evaluated. All mutations resulted in unregulated molecules displaying constitutive motor activity, similar to the mutant myosin underlying mlt. Thus, MYH11 mutations appear to contribute also to human intestinal neoplasia. Unregulated MYH11 may affect the cellular energy balance or disturb cell lineage decisions in tumor progenitor cells. These data challenge our view on MYH11 as a passive differentiation marker functioning in muscle contraction and add to our understanding of intestinal neoplasia.colorectal cancer ͉ microsatellite instability ͉ Peutz-Jeghers syndrome ͉ smmhc/myh11 G ermline mutations in human myosin heavy chain genes contribute to multiple inherited human diseases (1). In addition, smooth-muscle myosin (MYH11) participates in formation of an oncogenic fusion gene CBFB/MYH11 in acute myeloid leukaemia (2).Microsatellite instability (MSI) occurs in Ϸ15% of colorectal cancers (CRC), and is a consequence of defects in the DNA mismatch repair (MMR) system (3). Mutations occurring during DNA replication are not repaired, resulting in genetic instability that particularly affects short repetitive DNA sequences. Mutations that result in malignant progression are selected and thus detected in surgically removed MSI cancers. Passenger mutations also occur frequently in this mutator tumor type (4-6).By examining gene expression data (7), we had identified MYH11 as a gene with reduced expression in MSI CRCs compared with normal colon samples. The reduced expression of MYH11 in CRCs could simply reflect a larger smooth-muscle component in our normal colon specimens. Nevertheless, the differential expression prompted us to examine whether MYH11 has a mononucleotide tract in the coding sequence, because mononucleotide tracts are prone to mutations under MSI. Two splice variants, SM1 and SM2, which are distinct in the Cterminal tailpiece, are produced from the MYH11 gene. Indeed, the SM2 isoform of MYH11 was observed to harbor a mononucleotide repeat of 8 cytosines (C8). Thus, MYH11 was identified as a candidate MSI colon cancer gene. Dominant-negative germ-line mutations in MYH11 occur in a syndrome predisposing to thoracic aortic aneurysm/aortic dissection (TAAD) and patent ductus arteriosus (8). The TAAD phenotype closely resembles the on...

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“…Previous clinical research indicated that Smad4 is a predictive biomarker for 5-fluorouracil (5-FU)-based chemotherapy in patients with CRC (2)(3)(4)(5)(6). In addition, a recent in vitro study provided evidence that Smad4 inactivation promotes the resistance of CRC to 5-FU treatment and hypoxiainduced cell death (7).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, a recent in vitro study provided evidence that Smad4 inactivation promotes the resistance of CRC to 5-FU treatment and hypoxiainduced cell death (7). Low Smad4 expression in human CRC predicts early recurrence after curative therapy (4), less response to 5-FU (2,3) and shorter overall and disease-free survival time (2,3,8). However, the mechanism concerning the promotive effect of Smad4 on drug sensitivity remains to be elucidated.…”

Section: Introductionmentioning

confidence: 99%

Smad4 sensitizes colorectal cancer to 5-fluorouracil through cell cycle arrest by inhibiting the PI3K/Akt/CDC2/survivin cascade

Zhang

Leng

et al. 2015

Oncology Reports

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Abstract. 5-Fluorouracil (5-FU), a cell cycle-specific antimetabolite, is one of the most commonly used chemotherapeutic agents for colorectal cancer (CRC). Yet, resistance to 5-FU-based chemotherapy is still an obstacle to the treatment of this malignancy. Mutation or loss of Smad4 in CRC is pivotal for chemoresistance. However, the mechanism by which Smad4 regulates the chemosensitivity of CRC remains unclear. In the present study, we investigated the role of Smad4 in the chemosensitivity of CRC to 5-FU, and whether Smad4-regulated cell cycle arrest is involved in 5-FU chemoresistance. We used Smad4-expressing CT26 and Smad4-null SW620 cell lines as experimental models, by knockdown or transgenic overexpression. Cells or tumors were treated with 5-FU to determine chemosensitivity by cell growth, tumorigenicity assay and a mouse model. Cell cycle distribution was examined with flow cytometric analysis, and cell cycle-related proteins were examined by western blotting. Smad4 deficiency in CT26 and SW620 cells induced chemoresistance to 5-FU both in vitro and in vivo. Smad4 deficiency attenuated G1 or G2 cell cycle arrest by activating the PI3K/Akt/CDC2/survivin pathway. The PI3K inhibitor, LY294002, reversed the activation of the Akt/CDC2/survivin cascade in the Smad4-deficient cells, while it had little effect on cells with high Smad4 expression. In conclusion, we discovered a novel mechanism mediated by Smad4 to trigger 5-FU chemosensitivity through cell cycle arrest by inhibiting the PI3K/Akt/CDC2/survivin cascade. The present study also implies that LY294002 has potential therapeutic value to reverse the chemosensitivity of CRC with low Smad4 expression.

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SMAD4 Levels and Response to 5-Fluorouracil in Colorectal Cancer

Cited by 90 publications

References 39 publications

Transforming Growth Factor β Mediates Drug Resistance by Regulating the Expression of Pyruvate Dehydrogenase Kinase 4 in Colorectal Cancer

Transforming Growth Factor β Mediates Drug Resistance by Regulating the Expression of Pyruvate Dehydrogenase Kinase 4 in Colorectal Cancer

Unregulated smooth-muscle myosin in human intestinal neoplasia

Smad4 sensitizes colorectal cancer to 5-fluorouracil through cell cycle arrest by inhibiting the PI3K/Akt/CDC2/survivin cascade

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