CFTR reduces the proliferation of lung adenocarcinoma and is a strong predictor of survival in both smokers and non-smokers

The relationship between cancer risk and cystic fibrosis: the role of CFTR in cell growth and cancer development

Cystic fibrosis (CF) is a life-limiting genetic disease that affects multiple organ systems. It is caused by a mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which results in the absence or damage of a relevant protein. If left untreated, it causes death in early childhood. The advent of more efficacious treatments has resulted in a notable increase in the life expectancy of CF patients. This has, in turn, led to an elevated risk of developing specific types of cancer. This review commences with an examination of CF from the standpoint of its etiology and therapeutic modalities. Subsequently, it presents a list of epidemiological studies that suggest an altered predisposition to certain cancers. A heightened risk is well documented, particularly in relation to the gastrointestinal tract. The following section addresses the role of CFTR in view of its potential involvement in the progression of various types of cancer. Several studies have indicated that the levels of the CFTR protein are reduced in many tumors and that this reduction is associated with the progression of the tumors. These decreased expressions are known to occur in the gastrointestinal tract, lungs, bladder, and/or prostate cancer. Conversely, ovarian, stomach, and cervical cancer are connected with its higher expression. The final section of the review focuses on the molecular mechanism of action of the CFTR protein in signaling pathways that affect cell proliferation and the process of carcinogenesis. This section attempts to explain the increased predisposition to cancer observed in patients with CF.

Ivacaftor, a CFTR potentiator, synergizes with osimertinib against acquired resistance to osimertinib in NSCLC by regulating CFTR-PTEN-AKT axis

Osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has demonstrated significant clinical benefits in the treatment of EGFR-mutated non-small cell lung cancer (NSCLC). However, inevitable acquired resistance to osimertinib limits its clinical utility, and there is a lack of effective countermeasures. Here, we established osimertinib-resistant cell lines and performed drug library screening. This screening identified ivacaftor, a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator, as a synergistic enhancer of osimertinib-induced anti-tumor activity both in vitro and in vivo. Mechanistically, ivacaftor facilitated the colocalization of CFTR and PTEN on the plasma membrane to promote the function of PTEN, subsequently inhibiting the PI3K/AKT signaling pathway and suppressing tumor growth. In summary, our study suggests that activating CFTR enhances osimertinib-induced anti-tumor activity by regulating the PTEN-AKT axis. Furthermore, ivacaftor and osimertinib constitute a potential combination strategy for treating osimertinib-resistant EGFR-mutated NSCLC patients.

GATA6 Suppresses Lung Adenocarcinoma Progression by Activating CFTR to Modulate Arachidonic Acid Metabolism

BACKGROUND

CFTR, which belongs to the ATP-binding cassette transporter family and whose members are always involved in cancer progression, is implicated in lung adenocarcinoma (LUAD) progression, but the underlying mechanism remains undefined. Therefore, this study intended to investigate how CFTR works exactly on LUAD progression.

METHODS

Bioinformatics methods were utilized to analyze GATA6 and CFTR expression in LUAD and targeting relationship, followed by a pathway enrichment analysis of CFTR. GATA6 and CFTR expression levels were assessed by qRT-PCR. Cell viability and proliferation were detected through MTT and colony formation assays. An arachidonic acid (AA) assay kit was utilized to measure AA content. mRNA and protein expression levels of genes (cPLA2, COX-2, and CYP1A1) related to the AA metabolism pathway were detected by qRT-PCR and western blot, respectively. Moreover, the Dual-luciferase reporter gene assay and ChIP were used to verify the binding of GATA6 and CFTR promoters.

RESULTS

GATA6 and CFTR were lowly expressed in LUAD, and CFTR was enriched in the AA metabolism pathway. GATA6 activated CFTR transcription. Cellular and rescue experiments revealed that low or high CFTR expression could foster or hamper LUAD cell viability and proliferation, and concomitant treatment of indomethacin, an AA metabolism pathway inhibitor, mitigated stimulation on LUAD progression by low CFTR expression. Silencing of GATA6 reversed the suppressive impact of CFTR overexpression on LUAD progression via modulation of the AA metabolism pathway.

CONCLUSION

The activation of CFTR by GATA6 hampered LUAD progression by modulating the AA metabolism pathway, suggesting that GATA6/CFTR axis might be a therapeutic target for LUAD patients.

Loss of TTC17 promotes breast cancer metastasis through RAP1/CDC42 signaling and sensitizes it to rapamycin and paclitaxel

BACKGROUND

Breast cancer (BC) metastasis is the leading cause of poor prognosis and therapeutic failure. However, the mechanisms underlying cancer metastasis are far from clear.

METHODS

We screened candidate genes related to metastasis through genome-wide CRISPR screening and high-throughput sequencing of patients with metastatic BC, followed by a panel of metastatic model assays. The effects of tetratricopeptide repeat domain 17 (TTC17) on migration, invasion, and colony formation ability together with the responses to anticancer drugs were investigated in vitro and in vivo. The mechanism mediated by TTC17 was determined by RNA sequencing, Western blotting, immunohistochemistry, and immunofluorescence. The clinical significance of TTC17 was evaluated using BC tissue samples combined with clinicopathological data.

RESULTS

We identified the loss of TTC17 as a metastasis driver in BC, and its expression was negatively correlated with malignancy and positively correlated with patient prognosis. TTC17 loss in BC cells promoted their migration, invasion, and colony formation capacity in vitro and lung metastasis in vivo. Conversely, overexpressing TTC17 suppressed these aggressive phenotypes. Mechanistically, TTC17 knockdown in BC cells resulted in the activation of the RAP1/CDC42 pathway along with a disordered cytoskeleton in BC cells, and pharmacological blockade of CDC42 abolished the potentiation of motility and invasiveness caused by TTC17 silencing. Research on BC specimens demonstrated reduced TTC17 and increased CDC42 in metastatic tumors and lymph nodes, and low TTC17 expression was linked to more aggressive clinicopathologic characteristics. Through screening the anticancer drug library, the CDC42 inhibitor rapamycin and the microtubule-stabilizing drug paclitaxel showed stronger inhibition of TTC17-silenced BC cells, which was confirmed by more favorable efficacy in BC patients and tumor-bearing mice receiving rapamycin or paclitaxel in the TTC17^Low arm.

CONCLUSIONS

TTC17 loss is a novel factor promoting BC metastasis, that enhances migration and invasion by activating RAP1/CDC42 signaling and sensitizes BC to rapamycin and paclitaxel, which may improve stratified treatment strategies under the concept of molecular phenotyping-based precision therapy of BC.