The diapause-like colorectal cancer cells induced by SMC4 attenuation are characterized by low proliferation and chemotherapy insensitivity

In response to adverse environmental conditions, embryonic development may reversibly cease, a process termed diapause. Recent reports connect this phenomenon with the non-genetic responses of tumors to chemotherapy, but the mechanisms involved are poorly understood. Here, we establish a multifarious role for SMC4 in the switching of colorectal cancer cells to a diapause-like state. SMC4 attenuation promotes the expression of three investment phase glycolysis enzymes increasing lactate production while also suppressing PGAM1. Resultant high lactate levels increase ABC transporter expression via histone lactylation, rendering tumor cells insensitive to chemotherapy. SMC4 acts as co-activator of PGAM1 transcription, and the coordinate loss of SMC4 and PGAM1 affects F-actin assembly, inducing cytokinesis failure and polyploidy, thereby inhibiting cell proliferation. These insights into the mechanisms underlying non-genetic chemotherapy resistance may have significant implications for the field, advancing our understanding of aerobic glycolysis functions in tumor and potentially informing future therapeutic strategies.

RNA sequencing analysis of small cell lung cancer reveals candidate chemotherapy insensitivity long noncoding RNAs and microRNAs

BACKGROUND

The further progression of credible expression profiling analysis of genes continues to expand our understanding of the biological characteristics in lung cancer. In this study, RNA sequencing (RNA-Seq) was used to contrast the transcriptomics profiling of small cell lung cancer (SCLC) that acquired partial response (PR) and stable disease (SD)/progressive disease (PD) after first-line chemotherapy. We aimed to illuminate the underlying mechanisms of long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) in the efficacy of SCLC first-line chemotherapy.

METHODS

Six male patients (mean age, 64.2 years) with SCLC were enrolled in this study. RNA-Seq was executed on the tumor tissues from 3 patients with PR outcome and 3 patients with SD or PD therapeutic effect after first-line chemotherapy.

RESULTS

RNA-Seq generated 26.67×106 (±8.7×106) reads in SCLC tissues [mean (±standard deviation)]. Analysis revealed that 64 lncRNAs had higher expression and 194 had lower expression in the PR group ≥2-fold (P<0.05). Three downregulated genes in the PR group [HOXA-AS3, cancer susceptibility 9 (CASC9), and KEGG] could have a role in the insensitivity of SCLC. A total of 1,303 differential miRNAs were defined between PR and the SD or PD SCLC group, while 520 miRNAs had higher expression, and 783 had lower expression in the PR group. Two lower expressed miRNAs in the PR group (miRNA 601 and miRNA 596) might be the key genes in SCLC chemotherapy insensitivity.

CONCLUSIONS

The expression of 3 gene (HOXA-AS3, CASC9, and KEGG) and 2 miRNAs (miRNA 601 and miRNA 596) were markedly decreased in SCLC patients who achieved PR. They thus might be the promising candidate genes in SCLC chemotherapy insensitivity.