[Abstract unavailable

CD44 is a multifunctional protein involved in cell adhesion and signaling. The role of CD44 in prostate cancer (PCa) development and progression is controversial with studies showing both tumor-promoting and tumor-inhibiting effects. Most of these studies have used bulk-cultured PCa cells or PCa tissues to carry out correlative or overexpression experiments. The key experiment using prospectively purified cells has not been carried out. Here we use FACS to obtain homogeneous CD44 þ and CD44 À tumor cell populations from multiple PCa cell cultures as well as four xenograft tumors to compare their in vitro and in vivo tumor-associated properties. Our results reveal that the CD44 þ PCa cells are more proliferative, clonogenic, tumorigenic, and metastatic than the isogenic CD44 À PCa cells. Subsequent molecular studies demonstrate that the CD44 þ PCa cells possess certain intrinsic properties of progenitor cells. First, BrdU pulse-chase experiments reveal that CD44 þ cells colocalize with a population of intermediate label-retaining cells. Second, CD44 þ PCa cells express higher mRNA levels of several 'stemness' genes including Oct-3/4, Bmi, b-catenin, and SMO. Third, CD44 þ PCa cells can generate CD44 À cells in vitro and in vivo. Fourth, CD44 þ PCa cells, which are AR À , can differentiate into AR þ tumor cells. Finally, a very small percentage of CD44 þ PCa cells appear to undergo asymmetric cell division in clonal analyses. Altogether, our results suggest that the CD44 þ PCa cell population is enriched in tumorigenic and metastatic progenitor cells.

Tumor development has long been known to resemble abnormal embryogenesis. The embryonic stem cell (ESC) self-renewal gene NANOG is purportedly expressed by some epithelial cancer cells but a causal role in tumor development has remained unclear. Here, we provide compelling evidence that cultured cancer cells, as well as xenograft- and human primary prostate cancer cells (HPCa) express a functional variant of Nanog. NANOG mRNA in cancer cells is derived predominantly from a retrogene locus termed NANOGP8. NANOG protein is detectable in the nucleus of cancer cells and is expressed higher in patient prostate tumors than matched benign tissues. NANOGP8 mRNA and/or NANOG protein levels are enriched in putative cancer stem/progenitor cell populations. Importantly, extensive loss-of-function analysis reveals that RNAi-mediated Nanog knockdown inhibits tumor development, establishing a functional significance for Nanog expression in cancer cells. Nanog-shRNA transduced cancer cells exhibit decreased long-term clonal and clonogenic growth, reduced proliferation and, in some cases, altered differentiation. Thus, our results demonstrate that Nanog, a cell-fate regulatory molecule known to be important for ESC self-renewal, also plays a novel role in tumor development.

The human genetic code encrypted in thousands of genes holds the secret for synthesis of proteins that drive all biological processes necessary for normal life and death. Though the genetic ciphering remains unchanged through generations, some genes get disrupted, deleted and or mutated, manifesting diseases, and or disorders. Current treatment options—chemotherapy, protein therapy, radiotherapy, and surgery available for no more than 500 diseases—neither cure nor prevent genetic errors but often cause many side effects. However, gene therapy, colloquially called “living drug,” provides a one-time treatment option by rewriting or fixing errors in the natural genetic ciphering. Since gene therapy is predominantly a viral vector-based medicine, it has met with a fair bit of skepticism from both the science fraternity and patients. Now, thanks to advancements in gene editing and recombinant viral vector development, the interest of clinicians and pharmaceutical industries has been rekindled. With the advent of more than 12 different gene therapy drugs for curing cancer, blindness, immune, and neuronal disorders, this emerging experimental medicine has yet again come in the limelight. The present review article delves into the popular viral vectors used in gene therapy, advances, challenges, and perspectives.

Apoptosis induced by many stimuli requires the mitochondrial respiratory chain (MRC) function. While studying the molecular mechanisms underlying this MRC-dependent apoptotic pathway, we find that apoptosis in multiple cell types induced by a variety of stimuli is preceded by an early induction of MRC proteins such as cytochrome c (which is encoded by a nuclear gene) and cytochrome c oxidase subunit II (COX II) (which is encoded by the mitochondrial genome). Several non-MRC proteins localized in the mitochondria, e.g. Smac, Bim, Bak, and Bcl-2, are also rapidly up-regulated. The up-regulation of many of these proteins (e.g. cytochrome c, COX II, and Bim) results from transcriptional activation of the respective genes. The up-regulated cytosolic cytochrome c rapidly translocates to the mitochondria, resulting in an accumulation of holocytochrome c in the mitochondria accompanied by increasing holocytochrome c release into the cytosol. The increased cytochrome c transport from cytosol to the mitochondria does not depend on the mitochondrial protein synthesis or MRC per se. In contrast, cytochrome c release from the mitochondria involves dynamic changes in Bcl-2 family proteins (e.g. up-regulation of Bak, Bcl-2, and Bcl-x L ), opening of permeability transition pore, and loss of mitochondrial membrane potential. Overexpression of cytochrome c enhances caspase activation and promotes cell death in response to apoptotic stimulation, but simple up-regulation of cytochrome c using an ecdysone-inducible system is, by itself, insufficient to induce apoptosis. Taken together, these results suggest that apoptosis induced by many stimuli involves an early mitochondrial activation, which may be responsible for the subsequent disruption of MRC functions, loss of ⌬ m , cytochrome c release, and ultimately cell death.