Hi Ebinesh,

You can definitely do the tumor reversal experiments in vitro, however you cannot ideally reverse one tumor cell line back to a normal cell line. Even though, you can evaluate whether the target you are studying is able to reverse the malignant features of the tumor cells. For example, when you change tumor microenvironment, the tumor cells are growing slowly, and the tumor migration and invasion are reduced, etc.

Hope this information is helpful for you!

Hi Ebinesh,

You can definitely do the tumor reversal experiments in vitro, however you cannot ideally reverse one tumor cell line back to a normal cell line. Even though, you can evaluate whether the target you are studying is able to reverse the malignant features of the tumor cells. For example, when you change tumor microenvironment, the tumor cells are growing slowly, and the tumor migration and invasion are reduced, etc.

Hope this information is helpful for you!

I agree with Han. The experiments in vitro in this issue would mean very little because you cannot recreate in vitro the same conditions found in the tumor microenvironment.

Once you have a malignant phenotype there is a malignant genotype that creates and supports it. So that for a reversal you should be able to modify the genotype. And usually it is not one abnormal gene that creates the malignant state but a set of genes that tend to increase in number as tumor progression goes on.

regression is defined as a decrease in the size of the tumor or in the extent of cancer in the body according to the national cancer institute 

Thank you Dr. Han Zhang and Dr. Thomas Koltai. Is there any specific quantification methods (Such as titres) to add specific immune cells to cell lines?

Tumor reversal should be verified at three different levels:

a) molecular: tumor reversion is frequently associated with nuclear reprogramming of a few key-genes (like Oct-4, Sox-2 etc..). Namely, reversion can be tracked by monitoring EMT-dependent gene/protein expression (E-cadherin, Twist, Snail1, ZEB1, alpha-sma etc.). Briefly, a initial, critical step in inducing tumor reversion is chiefly dependent on the triggering of the mesenchymal-epitelial transition (MET). Altogether, some specific pathways (as such dependent on TCTP) should be specifically investigated. Indeed, a true "tumor reversion molecular programme" has been identified so far, thus demonstrating that cancer can be efficiently 'reverted', despite any genetic abnormalities (see at: Telerman A, Amson R, Hendrix MJ. Tumor reversion holds promise. Oncotarget 2010; 1: 233-4).

b) Reversion is associated with remarkable changes in cytoskeleton organization and cell behavior (motility, invasiveness. Cancer cells lose their motile phenotype (loss of pseudopodia, filopodia, reduction in stress fibers etc.) and display a different architectural redistribution of F-actin, microtubules, beta-catenin and E-cadherin.

c) ultimately, 'reversed' cancer cells could be able to reproduce (in 3D, but even in 2D), normal, morphological structures (such as ducts and lobules for reverting breast cancer cells). A final confirmation could also be obtained by transferring reverted cells into animals and evaluating the subsequent development of tumors.

This exciting field of research is extensively investigated in a few lab worldwide: A. Telerman lab (France), Mina Bissell (USA) as well as in my lab ( www.sbglab.org ). I am attaching here some useful reference data: 1)

Tumor reversion: mesenchymal-epithelial transition as a critical step in managing the tumor-microenvironment cross-talk. Bizzarri M, Cucina A, Proietti S. Curr Pharm Des. 2017 Jun 8; 2) Weaver VM, Petersen OW, Wang F, et al. Reversion of the malignant phenotype of human breast cells in three dimensional culture and in vivo by integrin blocking antibodies. J Cell Biol 1997; 137: 231-45. 3) Dinicola S, Fabrizi G, Masiello MG, et al. Inositol induces mesenchymal-epithelial reversion in breast cancer cells through cytoskeleton rearrangement. Exp Cell Res 2016; 345: 37-50. 4) Telerman A, Amson R. The molecular programme of tumour reversion: the steps beyond malignant transformation. Nat Rev Cancer 2009; 9: 206-16.

I would also add some further insights about tumor reversion. Indeed, reversion can be obtained through a) physical cues (i.e., by culturing cancer cells in a proper 3D-microenvironment); b) by using some pharmacological compound able to hit many target at the same time (i.e., inositol, embryonic factors, etc.); c) by selectively targeting a few genes/proteins pathways through a selected panel of micro-RNAs. See at: Plath K, Lowry WE. Progress in understanding reprogramming to the induced pluripotent state. Nat Rev Genet 2011; 12: 253-65 ; Bizzarri M, Cucina A, Biava PM, Proietti S, D’Anselmi F, Dinicola S, Pasqualato A, Lisi E, 2011, Embryonic morphogenetic field induces phenotypic reversion in cancer cells. Curr Pharm Biotechnol, vol. 12, pag. 243‑253.

Thanks a lot for sharing Dr. Bizzario. Indeed it was so useful. I'll see to it that I familiarise myself with this expanse of knowledge.