Most Read Articles
Pearl Toh, 22 Oct 2020
The combination therapy comprising carfilzomib, cyclophosphamide and dexamethasone (KCd) is effective, with a tolerable safety profile, in an Asian cohort with high-risk multiple myeloma (MM) — thus providing a more economical alternative as a potential upfront regimen in resource-limited settings, according to leading experts during a myeloma education webinar.
Pearl Toh, 21 Sep 2020
Early and sustained treatments with simplified regimen are the key to achieving good asthma control, said experts during a presentation at the ERS 2020 Congress.
3 days ago
Weight suppression appears to result in future onset of eating disorders characterized by dietary restriction or compensatory weight control behaviours, suggesting weight-suppressed women represent an at-risk group that may benefit from selective prevention programmes, a study has found.
4 days ago
Nocturia is a risk factor for mortality, according to the results of the Nagahama Study, which boasts of a low incidence of missing data and high representation of the general population.

E. coli strains potential agents of colorectal cancer

Rachel Soon
Medical Writer
30 Jul 2020

Certain Escherichia coli strains with carcinogenic potential are more prevalent in Malaysian patients with colorectal cancer (CRC) than healthy individuals, according to a new study.

The study enrolled 48 adult patients with CRC who had colon or rectal cancer resections performed at University Malaya Medical Centre (UMMC) between April 2014 and July 2015, as well as 23 healthy adults who went for colonoscopy at UMMC in the same period and had no previous history of inflammatory bowel disease (IBD), CRC, or any other cancers. Biopsies were taken from tumours in patients with CRC, as well as from normal mucosal colon tissues (proximal and distal) in both groups. [PLoS One 2020; doi: 10.1371/journal.pone.0228217]

Of the patients with CRC, eight had biopsies with E. coli strains possessing the polyketide synthetase (pks) genomic island, while only one of the healthy controls had the same (16.7 percent versus 4.3 percent, p=0.144). In the eight patients with CRC and pks+ E. coli colonization, the same bacterial strains were found in both tumour and normal colon samples.

“This finding is in agreement with previous studies wherein pks+ E. coli was over-represented in CRC patients as compared to those without cancer,” wrote the study authors. “In addition, we demonstrated that pks+ E. coli was found in both tumour and matching non-malignant tissue in CRC patients.”

Transmissible between individual bacteria, the pks genomic island allows the synthesis of colibactin, a genotoxic protein which has been linked to DNA damage and mutation, cell cycle arrest, and chromosomal instability in human cells. Previous studies in mouse models as well as patients with CRC have shown that pks+ E. coli are more often present in patients with CRC, while pks- strains appear to lack the same carcinogenic impact. [Science 2012;338(6103):120–123; PLoS One 2014; doi: 10.1371/journal.pone.0056964]

When the research team used the pks+ E. coli strains isolated from study participants to infect model cell lines of primary colon epithelial (PCE) and colorectal carcinoma (HCT 116) tissues, they found that the pks+ strains caused healthy cells to fuse together and swell abnormally, while the cancerous cells enlarged further (megalocytosis). The same effect was not observed when either cell line was infected by pks- E. coli strains isolated from the same patient cohort.

The results from the PCE cell line “may indicate that the presence of pks+ E. coli may be a risk factor contributing to the formation of tumourigenesis,” said the authors. They added that the cytopathic effect observed in the HCT 116 cell line might implicate pks+ E. coli in “the exacerbation of tumourigenesis, rather than just the initiation process.”

The authors noted that their study’s findings represented only one of multiple factors potentially contributing to CRC carcinogenesis and acknowledged the small sample size involved. They recommended future studies investigating the relationship between other factors such as dietary intake and lifestyle on the impact of pks+ E. coli in CRC.

The study was part of a bilateral collaboration between University Malaya and Johns Hopkins University School of Medicine, US.

Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS Doctor - Malaysia digital copy today!
Sign In To Download
Editor's Recommendations
Most Read Articles
Pearl Toh, 22 Oct 2020
The combination therapy comprising carfilzomib, cyclophosphamide and dexamethasone (KCd) is effective, with a tolerable safety profile, in an Asian cohort with high-risk multiple myeloma (MM) — thus providing a more economical alternative as a potential upfront regimen in resource-limited settings, according to leading experts during a myeloma education webinar.
Pearl Toh, 21 Sep 2020
Early and sustained treatments with simplified regimen are the key to achieving good asthma control, said experts during a presentation at the ERS 2020 Congress.
3 days ago
Weight suppression appears to result in future onset of eating disorders characterized by dietary restriction or compensatory weight control behaviours, suggesting weight-suppressed women represent an at-risk group that may benefit from selective prevention programmes, a study has found.
4 days ago
Nocturia is a risk factor for mortality, according to the results of the Nagahama Study, which boasts of a low incidence of missing data and high representation of the general population.