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Targeting Prion Protein to Overcome Doxorubicin Resistance in SCLC
Fatih Çöllü1, Hayrettin Kadinşah1, Zübeyde Öztel1
1Molecular Biology Section, Department of Biology, Faculty of Engineering and Natural Sciences, Manisa Celal Bayar University, Yunusemre-Manisa, Turkey.
Abstract:
Multidrug resistance (MDR) remains a major challenge in small cell lung cancer (SCLC), limiting the efficacy of chemotherapeutics like doxorubicin. This study investigates whether silencing cellular prion protein (PrP), a known MDR-associated molecule, can enhance doxorubicin-induced cell death in Adriamycin-resistant H69AR cells. Quantitative RT-PCR and immunocytochemistry were used to assess the expression of PRNP, CD44, BAX, and BECN1 under various treatment conditions, including doxorubicin exposure and PrP knockdown via siRNA. Autophagic activity was evaluated using monodansylcadaverine (MDC) staining. PrP knockdown significantly reduced PRNP expression and modulated CD44 mRNA levels, especially during doxorubicin co-treatment. However, CD44 protein levels remained unchanged, suggesting post-transcriptional regulation. BAX expression increased with doxorubicin and siRNA individually, but not in combination, indicating a PrP-independent mechanism. BECN1 expression and Beclin-1 protein levels were significantly elevated in all treatment groups, especially in siRNA/doxorubicin combination. MDC staining confirmed increased autophagic vacuole formation in this group, indicating activation of Beclin-1-mediated autophagy. In conclusion, PrP knockdown may sensitize resistant SCLC cells to doxorubicin and promote autophagy. These findings support PrP silencing as a promising strategy to reverse chemoresistance in SCLC.
Insights
Silencing cellular prion protein (PrP) may reverse multidrug resistance in small cell lung cancer (SCLC). This approach enhances doxorubicin efficacy and promotes autophagy in resistant SCLC cells.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Multidrug resistance (MDR) significantly limits chemotherapy effectiveness in small cell lung cancer (SCLC).
- Cellular prion protein (PrP) is implicated in MDR, potentially contributing to treatment failure.
- Doxorubicin is a key chemotherapeutic agent for SCLC, but its efficacy is often compromised by MDR.
Purpose of the Study:
- To investigate if silencing cellular prion protein (PrP) can overcome doxorubicin resistance in SCLC.
- To evaluate the impact of PrP knockdown on doxorubicin-induced cell death and autophagy in resistant SCLC cells.
- To analyze the expression of key genes (PRNP, CD44, BAX, BECN1) involved in drug resistance and apoptosis/autophagy.
Main Methods:
- Quantitative RT-PCR and immunocytochemistry were used to measure gene and protein expression.
- Small interfering RNA (siRNA) was employed to achieve PrP knockdown.
- Monodansylcadaverine (MDC) staining was utilized to assess autophagic activity.
Main Results:
- PrP knockdown significantly reduced PRNP mRNA and modulated CD44 mRNA levels, with no change in CD44 protein.
- BAX expression increased with individual treatments but not in combination, suggesting PrP independence.
- BECN1 expression and Beclin-1 protein levels were elevated, particularly with combined siRNA and doxorubicin, indicating activated autophagy.
Conclusions:
- PrP silencing shows potential to sensitize multidrug-resistant SCLC cells to doxorubicin.
- PrP knockdown promotes Beclin-1-mediated autophagy, contributing to enhanced cell death.
- Targeting PrP represents a promising strategy to overcome chemoresistance in SCLC.
