Elsevier

Gene

Volume 842, 30 October 2022, 146757
Gene

Research paper
ALDH6A1 weakens the progression of colon cancer via modulating the RAS/RAF/MEK/ERK pathway in cancer cell lines

https://doi.org/10.1016/j.gene.2022.146757Get rights and content

Highlights

  • ALDH6A1 expression was down-regulated in CC tissues and cells.

  • Oe-ALDH6A1 regulated the CC cell biological behaviors by via RAS/RAF/MEK/ERK pathway.

  • RAS/RAF inhibitor reversed the regulation of si-ALDH6A1 on the CC cells.

Abstract

Background

Aldehyde dehydrogenase 6 family member A1 (ALDH6A1) is associated with multiple diseases, but its pathogenesis in colon cancer (CC) is ambiguous and needs further study so that this research explores the function of ALDH6A1 in CC.

Methods

The level of ALDH6A1 in colon adenocarcinoma (COAD), CC tissues, and cells was measured by starBase v2.0, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot. Post transfection with overexpressed (oe)-ALDH6A1, cell biological behaviors, as well as apoptosis-, matrix metalloproteinase (MMP)-, and rat sarcoma virus (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway-related markers were measured by cell function experiments, qRT-PCR, and western blot. Next, the effects of small interfering RNA targeting ALDH6A1 (si-ALDH6A1) and RAS/RAF inhibitor (MCP110) on cell biological behaviors, as well as apoptosis-, MMP-, and RAS/RAF/MEK/ERK pathway-related markers were detected again.

Results

ALDH6A1 was low-expressed in COAD, CC tissues, and cells. Oe-ALDH6A1 weakened cell vitality, migration and invasionbut facilitated apoptosis; while it reduced expression levels of Bcl-2, MMP-2, MMP-9 and the RAS/RAF/MEK/ERK pathway-related markers but promoted Bax level. However, the regulation of si-ALDH6A1 on cell biological behaviors and related genes was opposite to that of oe-ALDH6A1. Moreover, MCP110 rescued the regulation of si-ALDH6A1 on cell biological behaviors, expressions of apoptosis- MMP- as well as RAS/RAF/MEK/ERK pathway-related markers. To sum up, ALDH6A1 attenuated CC progression by down-regulating the expressions of RAS/RAF/MEK/ERK pathway-related markers.

Introduction

It has been confirmed that colon cancer (CC) is a malignant tumor of the intestine caused by multiple factors such as heredity, diet, environment, and habits (Vargas and Thompson, 2012). In recent years, the incidence of CC in China has been increasing year by year due to the change of dietary structure and the reduction of dietary fiber intake (Chen et al., 2016). At present, the common treatment methods of CC include surgery, chemotherapy, radiotherapy, and target therapy (Nagarsheth et al., 2016, Tolba, 2020). Owing to the characteristics of CC, such as easy metastasis, easy recurrence and occult early-onset, most patients with CC are already in the middle and late stages when diagnosed, and thus lose the opportunity for surgical treatment (Hawinkels et al., 2014, Dougaz et al., 2019). Despite great improvement in the therapeutic effect of CC, chemotherapy has still confronted with many problems, such as tumor resistance, drug resistance, and strong side effects, which may limit the therapeutic effect of anticancer drugs and cause chemotherapy failure (Hu et al., 2016). Therefore, it is of great significance to fathom out the molecular mechanism of CC progression, search for its tumor markers, and then develop targeted drugs to prolong the survival time of patients.

With the development of transcriptomics and proteomics research technology, researchers have conducted in-depth research on CC at the molecular level. ALDH6A1, a member of aldehyde dehydrogenase (ALDH) family, is a type of protease that is ubiquitous in cells (Marcato et al., 2011). The increased activity of ALDHs can be observed in many normal cells and cancer stem cells, which can not only be used as markers but also play roles in self-protection, differentiation, and proliferation of cancer stem cells (Muzio et al., 2012). One study has clarified that ALDH6A1 can be used as prognostic markers for advanced metastatic prostate cancer (Cho et al., 2018). Another study has confirmed that ALDH6A1 may also be a biomarker related to metastasis and prognosis of hepatocellular carcinoma (HCC) (Liu et al., 2007). Grigo K. et al has discovered through RNA interference that ALDH6A1 may cooperate with HNF4 to inhibit the proliferation of renal cancer cells, but the specific mechanism still needs further study (Grigo et al., 2008). In addition, only one study has reported that the ectopic expression of ALDH6A1 is associated with CC (Pentheroudakis et al., 2014). However, the exact mechanism of ALDH6A1 in CC is obscure.

Aberrant modulation of mitogen-activated protein kinase (MAPK) cascades contributes to the progression of cancer and other human disorders. Especially, the extracellular signal-regulated kinase (ERK) MAPK pathway has been a highly active area of research in cancer treatment. Raf serine/threonine kinases activate the MAPK/ERK kinase (MEK)1/2 dual-specificity protein kinases, subsequently activating ERK1/2 (Roberts and Der, 2007). Besides, Ras family small GTPases, the most frequently mutated oncogenes in human cancers, are key upstream activators of Raf (Malumbres and Barbacid, 2003, Mitin et al., 2005). Recent major findings revealed that RAS/RAF/MEK/ERK signaling offers therapeutic candidates on clinical cancer therapy (Degirmenci et al., 2020). Some studies also revealed the important role of RAS/RAF/MEK/ERK signaling in characteristics of human CC cells (Li et al., 2017b, Wang et al., 2018, Wang et al., 2019). RAS/RAF/MEK/ERK pathway is also involved with ALDH expression in HCC (Harada et al., 2020).

In this study, we devoted to figuring out the role of ALDH6A1 in modulating the biological characteristics of CC cells, and delved into whether ALDH6A1 regulates RAS/RAF/MEK/ERK signaling to determine a potential therapeutic target for human CC.

Section snippets

Bioinformatic analysis

CC and normal control tissue data were downloaded from TCGA and differentially expressed genes were obtained using R language analysis. We found that the ALDH family member ALDH6A1 is poorly expressed in carcinoma tissues. Then, the data of ALDH6A1 in 471 colon adenocarcinoma (COAD) and 41 normal samples come from the TCGA (https://tcga-data.nci.nih.gov/tcga/) and were analyzed by starBase v2.0 (https://starbase.sysu.edu.cn).

Ethics statement

We obtained the 40 CC tissues and 40 adjacent normal tissues from

ALDH6A1 was low-expressed in CC tissues and cells and oe-ALDH6A1 weakened CC cell vitality, migration and invasion yet facilitated apoptosis

Bioinformatics analysis demonstrated that ALDH6A1 was lowly expressed in COAD (Fig. 1A, P = 6.8e-13). Subsequently, 40 CC patients met with inclusion criteria were included in this study (Table 1). We detected the expression of ALDH6A1 in CC tissues and adjacent tissues by qRT-PCR and western blot assays, revealing that ALDH6A1 was also low-expressed in CC tissues (Fig. 1B-1C, p < 0.001). Meanwhile, ALDH6A1 was also down-regulated in CC cells, including LS174T (Fig. 1D, P < 0.05), HCT116 (Fig. 1

Discussion

ALDH6A1 is proved to be hub gene in association with metastasis risk and prognosis in HCC (Chen et al., 2017), and down-regulated in HCC (Liu et al., 2007, Reis et al., 2015, Shin et al., 2020). Recently, Lu et al. (Lu et al., 2020) stated that ALDH6A1 exhibits a decreased expression in patients with clear cell renal cell carcinoma (ccRCC). Evidences reported by Guo et al. (Guo et al., 2022) revealed that ALDH6A1 expression level is downregulated in clinical bladder cancer tissues and bladder

Funding:

This work was supported by the Project of Dalian Health and Family Planning Commission [1811108].

Authors’ contributions

Substantial contributions to conception and design: Xiang Li, Nan Wang.

Data acquisition, data analysis and interpretation: Yutong Wu, Yidan Liu, Ruoyu Wang.

Drafting the article or critically revising it for important intellectual content: Xiang Li, Nan Wang.

Final approval of the version to be published: Xiang Li, Nan Wang, Yutong Wu, Yidan Liu, Ruoyu Wang.

Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of the work are

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Not applicable

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