MUC4 is highly regarded as a therapeutic target in pancreatic cancer as it is not expressed in healthy pancreas, while it is neoexpressed in early preneoplastic stages (PanINs).
We showed that MUC4 expression is associated with a poorer overall survival in TCGA cancers with different localizations including pancreatic cancer, bladder cancer, colon cancer, lung adenocarcinoma, lung squamous adenocarcinoma, skin cancer and stomach cancer.
In line with these findings, doxycycline-induced expression of MUC4/X in an endogenous WT-MUC4 expressing PC cell line (Capan-1) also displayed enhanced cell proliferation, invasion, and adhesion to ECM, compared to WT-MUC4 alone, emphasizing its direct involvement in the aggressive behavior of PC cells.
Our results demonstrate: 1) NIDO, AMOP, and vWD domain or their synergy play significant roles on MUC4/Y-mediated malignant function of pancreatic cancer, downstream of molecule mechanisms, particularly MUC4/Y-triggered malignancy-related positive feedback loops, respectively.
Additionally, future studies evaluating MUC4 as a target for immunotherapy must entail characterization of immune response in PC patients and investigate its association with immunosuppression and survival.
Altogether, hypoxia-mediated oxidative stress induces autophagy in PC, leading to the MUC4 degradation to enhance survival, possibly by offering required metabolites to stressed cells.
The oncogenic mucin MUC4 has been identified as an actor of pancreatic carcinogenesis as it is involved in many processes regulating pancreatic cancer cell biology.
The mucin MUC4 is a transcriptional and post-transcriptional target of K-ras oncogene in pancreatic cancer. Implication of MAPK/AP-1, NF-κB and RalB signaling pathways.
Besides, we and others have demonstrated de novo expression of MUC4 in ~70-90% of pancreatic cancer patients and its stabilizing effects on HER2 downstream signaling in pancreatic cancer.
A 76-member combined epigenetics and phosphatase small-molecule inhibitor library was screened for anti-proliferative activity against the MUC4(+) gemcitabine-resistant pancreatic cancer cell line Capan-1, followed by high-content screening of protein expression.
Monoclonal antibody 8G7 showed a clear immunoreactivity, whereas MAb 1G8 did not show any immunoreactivity, in the Western blotting and IHC for human pancreatic carcinoma cell lines expressing MUC4 messenger RNA.
CAPAN-2 and CAPAN-1 adenocarcinomatous pancreatic cancer (PC) cell lines were used to establish stable MUC4-deficient clones (MUC4-KD) by shRNA interference.
Altogether, our findings revealed for the first time that CS upregulates the MUC4 mucin in PC via the α7nAChR/JAK2/STAT3 downstream signaling cascade, thereby promoting metastasis of PC.
MUC4 was also found to be necessary for the nicotine-mediated invasion of pancreatic cancer cells, suggesting that induction of MUC4 by nicotine and other agents might contribute to the genesis and progression of pancreatic cancer.
MUC4 is a large transmembrane type I glycoprotein that is overexpressed in pancreatic cancer (PC) and has been shown to be associated with its progression and metastasis.
Overall, this study corroborates with previous human studies that indicated the aberrant overexpression of MUC1, MUC4 and MUC5AC mucins during the progression of PC.