How desirable and undesirable features of naïve or genetically reengineered mesenchymal stem cells are being considered in preclinical or clinical assays.

The implantation of adult mesenchymal stem cells (MSCs) has become a promising alternative in cancer treatments. Accordingly, in this article we revised the ultimate advances in the knowledge on the MSC-homing mechanism, the cancer cell and MSCs interactions and the microvesicles and exosomes used by malignant cells to transport and deliver pro-cancer cytokines or microRNA (miRNA), or by MSCs to favor or fight cancer progression. In addition, we analyzed the current knowledge generated by ongoing or terminated preclinical and clinical trials, using naive MSCs as natural anti-cancer living factors or gene-engineered MSCs as cytokine delivering vehicles, where anti-cancer cytokines were chosen and the pro-cancer factors were avoided. Finally, we present some concerns about the implantation of MSCs and anti-cancer therapies and hypothesize the MSC implantation combines with conventional or new therapies to treat cancer.

Thymidylate synthase polymorphism in Mexican patients with colon cancer treated with 5-fluorouracil.

PURPOSE: We analyzed the genotype and allele frequency of variable number tandem repeats (VNTR)-thymidylate synthase (TS) and its relationship with the disease evolution in colon cancer patients. METHODS: We selected 24 paraffin-embedded colon cancer tissue samples from Mexican patients who received a 5-fluorouracil (5-FU)-based chemotherapy regimen. Tumor tissue was digested with proteinase K and genomic DNA was isolated by the standard method with phenol-chloroform extraction. Polymerase chain reaction (PCR) was performed for TS genotyping of VNTR and the results were evaluated directly in a stained agarose gel. RESULTS: The allele frequency of 2 repeats (2R) was greater (0.66) than 3R (0.34) in metastatic colon cancer (x2=10.24; p=0.001)) however, no difference in allelic distribution between 2R (0.54) and 3R (0.46) in non metastatic patients was observed (x2=0.640; p=0.424). CONCLUSION: Our results suggest that Mexican patients with colon cancer present differences in the allelic distribution, the 2R allele being the most frequent.