Investigating the Role of MUC19 in Glioblastoma Multiforme: Genetic Alterations and Implications for Patient Survival and Therapeutic Targeting

Introduction

Glioblastoma multiforme (GBM) is the most aggressive and common primary malignant brain tumor, accounting for approximately 45-50% of such cases.¹ GBM typically originates from astrocytes, star-shaped cells that form part of the brain’s supportive tissue.² It is more prevalent in older males than females. Despite aggressive treatments, such as surgical resection, radiotherapy, and chemotherapy, patient prognosis remains poor, with only minimal improvements in survival rates.³ GBM most commonly arises in the cerebral cortex, but can also occur in other areas, such as the spinal cord.⁴ Understanding the genetic alterations that occur in glioblastoma, particularly in deceased patients, is vital for unraveling tumor behavior, resistance mechanisms, and patient outcomes.⁵

Mutations in genes such as Phosphatase And Tensin Homolog (PTEN) and Epidermal Growth Factor Receptor (EGFR) contribute to aggressive tumor progression and poor survival rates.⁶ For example, EGFR mutations are linked to shorter survival times, whereas loss of PTEN is associated with treatment resistance.⁷ These genetic insights are critical for the development of personalized treatment strategies.⁸ However, limited research has comprehensively analyzed the relationship between specific genetic alterations and survival outcomes in glioblastoma, a gap this study seeks to fill.⁹ One such gene of interest is MUC19, a mucin family gene that plays a significant role in producing protective mucous layers in epithelial cells.¹⁰ While MUC19 is primarily linked to diseases such as inflammatory bowel disease, recent studies have suggested its involvement in cancer, making it a key target for understanding glioblastoma pathogenesis and potential therapeutic interventions.¹¹

This study aimed to comprehensively analyze the genetic mutations in patients with glioblastoma, focusing on deceased patients. By organizing and assessing 16 significant studies, we aimed to investigate the influence of these genetic changes on survival outcomes. This analysis will provide insights into critical genes linked to disease progression and mortality, with the aim of identifying potential therapeutic targets and improving prognosis prediction in glioblastoma patients.

Methods

Results

The top ten mutated genes were significantly enriched in the deceased group of patients with GBM ( Table 1). These genes, including PTEN, Aquaporin 7 Pseudogene 1 (AQP7P1), EGFR, MUC19, FSHD Region Gene 2 Family Member B (FRG2B), Mucin 17 (MUC17), Transmembrane Protein 191A (TMEM191A), Mucin 16 (MUC16), Rho Guanine Nucleotide Exchange Factor 33 (ARHGEF33), and NACHT And WD Repeat Domain Containing 2 (NWD2), had notably higher mutation rates in the deceased group than in the living group. The analysis highlights the cytoband locations, mutation rates, and statistical significance of the differences, measured through p-values and q-values. Three members of the mucin (MUC) gene family (MUC19, MUC17, and MUC16) were prominent, with MUC19 being the most significant gene in the group.

The effect of siRNA targeting MUC19 (siMUC19) on MUC19 expression levels and cell viability in A172 glioblastoma cells was analyzed ( Figure 1). The gel electrophoresis results showed two bands corresponding to MUC19 and GAPDH in the negative control (NC) and siMUC19-treated cells ( Figure 1A). After siRNA treatment, MUC19 expression in the siMUC19 group was significantly reduced compared with that in the control group. Quantitative analysis revealed that control cells showed significantly decreased cell viability ( Figure 1A).

Figure 1. siRNA targeting MUC19 (siMUC19) significantly decreases mRNA MUC19 expression and reduces viability in A172.

(A) Gel electrophoresis results showing MUC19 and GAPDH (control) expression in negative control (NC) and siMUC19-treated A172 cells seven days post-transfection. The siMUC19 group exhibits significantly reduced MUC19 expression compared to the control (p = 0.0029) (N = 3). (B) Quantitative analysis of cell viability after siMUC19 transfection. Representative microscopy images demonstrating decreased cell density in siMUC19-treated cells compared to the control group. The bar graph shows significantly lower MUC19 expression in the siMUC19 group compared to the control (p = 0.0336) (N = 3), Scale bar = 200 μm.

The normalized MUC19 expression levels in the siMUC19 group were significantly lower than those in the control group, and microscopic images further confirmed a decrease in cell density ( Figure 1B). siMUC19-treated cells exhibited visibly fewer cells than the control group, supporting the observation of reduced cell growth. Statistical analysis revealed a significant difference between the two groups, with a p-value of 0.0336 ( Figure 1B). These findings suggest that MUC19 plays a key role in glioblastoma cell growth, supporting the hypothesis that targeting MUC19 could be a potential therapeutic strategy.

Discussion

This study provides significant insights into the genetic alterations associated with glioblastoma multiforme (GBM) mortality and highlights potential therapeutic targets, mainly focusing on mucin genes. Our findings revealed important differences in mutation frequencies between deceased and living GBM patients, offering new perspectives on disease progression and potential treatment strategies.

Our analysis identified ten key mutated genes that were significantly enriched in deceased GBM patients, suggesting their potential role in disease severity and mortality. These genes, including PTEN, EGFR, AQP7P1, and FRG2B, as well as three mucin genes (MUC19, MUC17, and MUC16), were selected based on their low q-values and p-values, indicating strong statistical significance. The diverse chromosomal locations of these genes and their higher presence in deceased individuals emphasize their possible involvement in critical biological processes that impact patient outcomes.

The identification of well-known cancer-associated genes, such as PTEN and EGFR, in our analysis, aligns with previous studies, reinforcing their importance in GBM pathogenesis.¹³ PTEN loss and EGFR amplification have been associated with poorer survival outcomes in patients with GBM, suggesting that personalized treatment strategies targeting these alterations could be more effective.¹⁴ PTEN, which is located on chromosome 10q23.31, regulates cell growth and division.¹⁵ Its mutation rate of 26.37% in deceased patients compared to 12.16% in living patients underscores its significance in GBM progression. EGFR, found on chromosome 7p11.2, is involved in the cell growth and survival pathways. Its amplification, observed in 20.41% of deceased patients versus 8.75% of living patients, further emphasizes its role in aggressive GBM phenotypes. AQP7P1, a gene encoding an integral membrane protein involved in water transport, showed a striking difference, with a 23.16% mutation rate in deceased patients compared to 0% in living patients.¹⁶ This finding suggests a potential novel role of this gene in GBM pathogenesis, which warrants further investigation.

A novel aspect of our findings is the identification of three mucin genes (MUC19, MUC17, and MUC16) among the top mutated genes in deceased patients with GBM. Although these genes are traditionally associated with the formation of protective mucous barriers in various bodily systems, their involvement in cancer pathogenesis, particularly in GBM, is less understood.¹⁷ MUC19 emerged was the most significant mucin gene in our analysis, with a mutation rate of 4.55% in deceased patients compared with 0% in living patients. Our siRNA experiments targeting MUC19 demonstrated a significant reduction in cell viability in A172 glioblastoma cells, suggesting its potential role in tumor cell survival and proliferation. These results indicate that MUC19 may be a viable therapeutic target, with the potential for the future development of targeted therapies aimed at silencing MUC19 expression. MUC17, located on chromosome 7q22.1, had a mutation rate of 9.93% in deceased patients versus 2.68% in living patients. This gene is known to play a role in creating a mucous barrier that protects the digestive system lining.¹⁸ Its increased mutation rate in deceased GBM patients suggests a potential role in tumor progression, possibly through cell adhesion or signaling pathway alterations. MUC16, found on chromosome 19p13.2, exhibited a mutation rate of 17.19% in deceased patients compared with 8.14% in living patients. This gene forms protective barriers on epithelial surfaces and is involved in cellular adhesion and immune responses. The higher mutation rate in deceased GBM patients may indicate a role in immune evasion or altered cell-cell interactions in more aggressive tumors.¹⁹ The roles of MUC17 and MUC16 in GBM progression require further investigation. Their potential contributions to GBM pathogenesis may involve cell adhesion, signaling, and immune modulation mechanisms that are yet to be fully elucidated in the context of brain tumors.²⁰

Although our study provides valuable insights, it has several limitations that should be addressed in future research. Our reliance on data from deceased GBM patients may introduce bias as these patients likely have more aggressive tumor phenotypes. Future studies should include a more balanced cohort of patients at various disease stages to provide a more comprehensive understanding of the genetic alterations throughout GBM progression.²¹ Focusing on mutations in specific genes may overlook other potential factors such as epigenetic changes or microenvironmental influences, which could also significantly affect patient outcomes. A more comprehensive approach that incorporates these factors would provide a fuller picture of GBM progression and potentially reveal additional therapeutic targets. While our siRNA experiments provided evidence for the role of MUC19 in glioblastoma cell viability, further studies are needed to explore the exact mechanisms by which MUC19, MUC17, and MUC16 contribute to tumor progression.²⁰

This study highlights the importance of genetic alterations, particularly in mucin genes, in GBM progression and mortality. These findings underscore the potential for developing personalized treatment strategies targeting MUC19, MUC17, and MUC16 in future therapeutic approaches. Although our results provide a promising foundation, further research is essential to validate these findings and explore new avenues for GBM treatment.