This study analyzed SCAMP2 expression in paired colorectal cancer and adjacent non-tumor tissues collected at a single center between January 2022 and March 2023. Protein-level assessment by Western blot in seven available tissue pairs demonstrated lower SCAMP2 expression in colorectal cancer relative to adjacent normal intestinal tissue. Immunohistochemistry results were consistent: both SCAMP2 and EGR1 showed strong positive staining (3+) in normal intestinal epithelium but negative or weakly positive staining (1+) in colorectal cancer specimens. These tissue-level observations indicate reduced activity of the SCAMP2/EGR1 axis in tumor tissue compared with normal mucosa.
The investigators used two colorectal cancer cell lines, SW480 and HT29, to interrogate function. They established overexpression and knockdown models using small interfering RNA (siRNA), short hairpin RNA (shRNA), lentiviral SCAMP2 overexpression constructs, and EGR1 overexpression plasmids. These manipulations enabled assessment of causal effects of altering SCAMP2 and EGR1 levels on cell proliferation and apoptosis in controlled in vitro experiments.
Functional readouts included CCK8 assays to measure proliferation and flow cytometry to quantify apoptosis. Overexpression of either SCAMP2 or EGR1 significantly suppressed proliferation of colorectal cancer cells (reported as P < 0.05). In parallel, SCAMP2 overexpression promoted apoptosis. Conversely, knockdown of SCAMP2 enhanced proliferative behavior and reduced apoptosis. These complementary in vitro results support a growth-suppressive, pro-apoptotic role for the SCAMP2/EGR1 signaling axis in the tested colorectal cancer cell lines.
To evaluate effects in vivo, the authors used a nude mouse subcutaneous xenograft model. SCAMP2 overexpression in tumor cells produced a marked inhibition of tumor growth in this model (P < 0.05). This in vivo observation aligns with the in vitro findings and supports the biological relevance of SCAMP2-mediated growth suppression beyond cultured cells.
Transcriptome sequencing performed on SCAMP2-overexpressing colorectal cancer cells identified changes in gene expression profiles. Notably, the mRNA level of EGR1 was significantly upregulated in SCAMP2-overexpressing cells (P < 0.05). The sequencing results guided the focus on EGR1 as a downstream regulatory factor of SCAMP2, providing molecular evidence that SCAMP2 may exert its effects through modulation of EGR1 expression.
The study used reciprocal rescue experiments to probe the interaction between SCAMP2 and EGR1. Knockdown of EGR1 partially reversed the inhibitory effect on proliferation and the pro-apoptotic influence induced by SCAMP2 overexpression. Conversely, overexpression of EGR1 partially mitigated the enhanced proliferation and reduced apoptosis caused by SCAMP2 knockdown. These bidirectional rescue data indicate a functional dependency between SCAMP2 and EGR1 in controlling colorectal cancer cell proliferation and survival, consistent with an operative SCAMP2/EGR1 signaling axis.
The authors conclude that SCAMP2 is downregulated in colorectal cancer and that low SCAMP2 expression may impair EGR1 signaling, thereby reducing apoptosis and promoting proliferation of colorectal cancer cells. Both in vitro and in vivo data support a tumor-suppressive role for the SCAMP2/EGR1 axis. The findings suggest this signaling pathway may contribute to colorectal cancer progression and could represent a molecular target for further investigation.
Limitations and reporting scope: The abstract reports sample collection, broad experimental methods, and principal outcomes including statistical significance (P < 0.05) for key comparisons. Detailed numeric results, full statistical values, precise sample counts for each assay beyond the tissue pairs, and longer-term or clinical outcome correlations were not reported in the abstract. All authors declared no conflicts of interest. Further work would be needed to validate these results in larger clinical cohorts and to explore therapeutic implications, which are not addressed in the source abstract.