Major differences between tumor and normal human cell fates after exposure to chemotherapeutic monofunctional alkylator

The major dilemma of cancer chemotherapy has always been a double-edged sword, producing resistance in tumor cells and life-threatening destruction of nontumorigenic tissue. Glioblastoma is the most common form of primary brain tumor, with median survival at 14 months after surgery, radiation and temozolomide (monofunctional alkylator) therapy. Treatment failure is most often due to temozolomide-resistant tumor growth. The underlying basis for development of tumor cell resistance to temozolomide instead of death is not understood. Our current results demonstrate that both cervical carcinoma (HeLa MR) and glioblastoma (U251) tumor cells exposed to an equivalent chemotherapeutic concentration of a monofunctional alkylator undergo multiple cell cycles, maintenance of metabolic activity, and a prolonged time to death that involves accumulation of Apoptosis Inducing Factor (AIF) within the nucleus. A minority of the tumor cell population undergoes senescence, with minimal caspase cleavage. Surviving tumor cells are comprised of a very small subpopulation of individual cells that eventually resume proliferation, out of which resistant cells emerge. In contrast, normal human cells (MCF12A) exposed to a monofunctional alkylator undergo an immediate decrease in metabolic activity and subsequent senescence. A minority of the normal cell population undergoes cell death by the caspase cleavage pathway. All cytotoxic events occur within the first cell cycle in nontumorigenic cells. In summation, we have demonstrated that two different highly malignant tumor cell lines slowly undergo very altered cellular and temporal responses to chemotherapeutic monofunctional alkylation, as compared to rapid responses of normal cells. In the clinic, this produces resistance and growth of tumor cells, cytotoxicity of normal cells, and death of the patient.

Hypoxia differentially regulates human nucleus pulposus and annulus fibrosus cell extracellular matrix production in 3D scaffolds

OBJECTIVE

We hypothesize that intervertebral disc (IVD) cells from distinct region respond differently to oxygen environment, and that IVD cells from patients with disc degeneration can benefit from hypoxia condition. Therefore, we aimed to determine the transcriptional response and extracellular matrix (ECM) production of nucleus pulposus (NP) and annulus fibrosus (AF) cells to different oxygen tension.

METHOD

Human NP and AF from degenerated IVD were seeded in 3D scaffolds and subjected to varying oxygen tension (2% and 20%) for 3 weeks. Changes in ECM were evaluated using quantitative real-time reverse transcriptase polymerase chain reaction, histological and immunohistological analyses.

RESULTS

Hypoxia significantly enhances NP cells phenotype, which resulted in greater production of sulfated glycosaminoglycan (GAG) and collagen type II within the constructs and the cells expressed higher levels of genes encoding NP ECM. A significantly stronger fluorescent signal for hypoxia-inducible factor (HIF-1α) as also found in the NP cells under the hypoxic than normoxic condition. However, there was little effect of hypoxia on the AF cells.

CONCLUSIONS

The NP and AF cells respond differently to hypoxia condition on the 3D scaffold, and hypoxia could enhance NP phenotype. When used in concert with appropriate scaffold material, human NP cells from degenerated disc could be regenerated for tissue engineering application.

Antifungal antibiotics

The search for new drugs against fungal infections is a major challenge to current research in mycotic diseases. The present article reviews the current types of antifungal infections, the current scenario of antifungal antibiotics, and the need and approaches to search for newer antifungal antibiotics and antifungal drug targets.